Mammalian hck, a member of the src family of tyrosine kinases, is expressed predominantly in cell... more Mammalian hck, a member of the src family of tyrosine kinases, is expressed predominantly in cells of the myeloid and B-lymphoid lineages. Using mutational analysis, we have investigated the molecular basis of two immunoreactive forms of murine hck of 56 and 59 kDa found in numerous hemopoietic cell types. Our results indicate that translation of murine p59hck initiates from a CTG codon located 21 codons 5' of an ATG that is utilized to generate p56hck. We provide evidence that two human hck isoforms are generated by the same mechanism. Subcellular fractionation studies reveal that while p59hck and pS6'ck are associated with membranes of various murine B-lymphoid and myeloid cell lines, p59hck alone is also located in the cytosol. In contrast to membrane-associated p59hck, which is metabolically labeled with [3HJmyristic acid and exhibits amphiphilic properties in Triton X-114 detergent, cytosolic p59hck is hydrophilic, suggesting that it is not acylated. Possible mechanisms are proposed to account for these observations.
Several diverse proteins are linked genetically/pathologically to neurodegeneration in amyotrophi... more Several diverse proteins are linked genetically/pathologically to neurodegeneration in amyotrophic lateral sclerosis (ALS) including SOD1, TDP-43 and FUS. Using a variety of cellular and biochemical techniques, we demonstrate that ALS-associated mutant TDP-43, FUS and SOD1 inhibit protein transport between the endoplasmic reticulum (ER) and Golgi apparatus in neuronal cells. ER-Golgi transport was also inhibited in embryonic cortical and motor neurons obtained from a widely used animal model (SOD1 G93A mice), validating this mechanism as an early event in disease. Each protein inhibited transport by distinct mechanisms, but each process was dependent on Rab1. Mutant TDP-43 and mutant FUS both inhibited the incorporation of secretory protein cargo into COPII vesicles as they bud from the ER, and inhibited transport from ER to the ER-Golgi intermediate (ERGIC) compartment. TDP-43 was detected on the cytoplasmic face of the ER membrane, whereas FUS was present within the ER, suggesting that transport is inhibited from the cytoplasm by mutant TDP-43, and from the ER by mutant FUS. In contrast, mutant SOD1 destabilised microtubules and inhibited transport from the ERGIC compartment to Golgi, but not from ER to ERGIC. Rab1 performs multiple roles in ER-Golgi transport, and over-expression of Rab1 restored ER-Golgi transport, and prevented ER stress, mSOD1 inclusion formation and induction of apoptosis, in cells expressing mutant TDP-43, FUS or SOD1. Rab1 also co-localised extensively with mutant TDP-43, FUS and SOD1 in neuronal cells, and Rab1 formed inclusions in motor neurons of spinal cords from sporadic ALS patients, which were positive for ubiquitinated TDP-43, implying that Rab1 is misfolded and dysfunctional in sporadic disease. These results demonstrate that ALS-mutant forms of TDP-43, FUS, and SOD1 all perturb protein transport in the early secretory pathway, between ER and Golgi compartments. These data also imply that restoring Rab1mediated ER-Golgi transport is a novel therapeutic target in ALS.
Mammalian hck, a member of the src family of tyrosine kinases, is expressed predominantly in cell... more Mammalian hck, a member of the src family of tyrosine kinases, is expressed predominantly in cells of the myeloid and B-lymphoid lineages. Using mutational analysis, we have investigated the molecular basis of two immunoreactive forms of murine hck of 56 and 59 kDa found in numerous hemopoietic cell types. Our results indicate that translation of murine p59hck initiates from a CTG codon located 21 codons 5' of an ATG that is utilized to generate p56hck. We provide evidence that two human hck isoforms are generated by the same mechanism. Subcellular fractionation studies reveal that while p59hck and p56hck are associated with membranes of various murine B-lymphoid and myeloid cell lines, p59hck alone is also located in the cytosol. In contrast to membrane-associated p59hck, which is metabolically labeled with [3H]myristic acid and exhibits amphiphilic properties in Triton X-114 detergent, cytosolic p59hck is hydrophilic, suggesting that it is not acylated. Possible mechanisms are...
To examine the effect of waiting times on the health status of patients referred for a non-urgent... more To examine the effect of waiting times on the health status of patients referred for a non-urgent rheumatology opinion. The study was a randomized controlled clinical study evaluating a 'fast track' appointment with a 6-week target waiting time against an 'ordinary' appointment in the main city out-patient clinic of the rheumatology service for the Lothian and Borders region (population approximately 1 million). Health status was measured using the SF12 physical and mental summary component T-scores and pain was measured with a 100 mm visual analogue pain scale. Secondary outcomes were health utility and perceived health both measured with the EuroQol instrument, mental health measured with the Hospital Anxiety and Depression scale, disability with the modified Health Assessment Questionnaire and economic costs measured from a societal perspective. Mean waiting times were 43 days (sigma = +/-16) and 105 days (sigma = +/-51) for 'fast track' and 'ordinary&...
The structure and function of the promoter region and exon 1 of the murine hck gene have been cha... more The structure and function of the promoter region and exon 1 of the murine hck gene have been characterized in detail. RNase protection analysis has established that hck transcripts initiate from heterogeneous start sites located within the hck gene. Fusion gene constructs containing hck 5'-flanking sequences and the bacterial Neor gene have been introduced into the hematopoietic cell lines FDC-P1 and WEHI-265 by using a self-inactivating retroviral vector. The transcriptional start sites of the fusion gene are essentially identical to those of the endogenous hck gene. Analysis of infected WEHI-265 cell lines treated with bacterial lipopolysaccharide (LPS) reveals a 3- to 5-fold elevation in the levels of endogenous hck mRNA and a 1.4- to 2.6-fold increase in the level of Neor fusion gene transcripts, indicating that hck 5'-flanking sequences are capable of conferring LPS responsiveness on the Neor gene. The 5'-flanking region of the hck gene contains sequences similar t...
Two lyn proteins of 56 and 53 kDa have been observed in immunoprecipitates from a variety of muri... more Two lyn proteins of 56 and 53 kDa have been observed in immunoprecipitates from a variety of murine and human cell lines and tissues. We report the cloning and nucleotide sequence of two distinct murine lyn cDNAs isolated from an FDC-P1 cDNA library. One of the cDNAs, designated lyn11, encodes a protein of 56 kDa which shares 96% similarity with human lyn. The other cDNA, designated lyn12, encodes a protein of 53 kDa. The proteins differ in the presence or absence of a 21-amino-acid sequence located 24 amino acids C terminal of the translational initiation codon. Using RNase protection analysis, we have identified mRNAs corresponding to both cDNAs in murine cell lines and tissues. Sequence analysis of murine genomic clones suggests that the distinct mRNAs are alternatively spliced transcripts derived from a single gene. Expression of both cDNAs in COS cells leads to the production of lyn proteins with the same molecular weight as the two forms of lyn proteins immunoprecipitated from...
We have examined the role of tyrosine phosphorylation during the course of macrophage activation.... more We have examined the role of tyrosine phosphorylation during the course of macrophage activation. Initial experiments indicated that vanadate, a known phosphotyrosine phosphatase inhibitor, enhanced the phorbol 12-myristate 13-acetate (PMA)-triggered respiratory burst and potentiated the priming effects of bacterial lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma), suggesting that tyrosine phosphorylation may be important in these end cell functions. As src-related kinases have been implicated in the activation of cells of other haemopoietic lineages, we examined the relationship between the activity of two such kinases, hck and lyn, and priming of the respiratory burst. We found that the level of hck and lyn is increased following exposure of bone marrow-derived macrophages (BMM) to LPS or IFN-gamma. The induction of both of these kinases follows similar kinetics with maximal activity occurring at 24-48 h. Interestingly, the kinetics of induction of hck and lyn kinase acti...
Both receptor-interacting protein kinase 1 (RIPK1) and RIPK3 can signal cell death following deat... more Both receptor-interacting protein kinase 1 (RIPK1) and RIPK3 can signal cell death following death receptor ligation. To study the requirements for RIPK-triggered cell death in the absence of death receptor signaling, we engineered inducible versions of RIPK1 and RIPK3 that can be activated by dimerization with the antibiotic coumermycin. In the absence of TNF or other death ligands, expression and dimerization of RIPK1 was sufficient to cause cell death by caspase- or RIPK3-dependent mechanisms. Dimerized RIPK3 induced cell death by an MLKL-dependent mechanism but, surprisingly, also induced death mediated by FADD, caspase 8 and RIPK1. Catalytically active RIPK3 kinase domains were essential for MLKL-dependent but not for caspase 8-dependent death. When RIPK1 or RIPK3 proteins were dimerized, the mode of cell death was determined by the availability of downstream molecules such as FADD, caspase 8 and MLKL. These observations imply that rather than a 'switch' operating between the two modes of cell death, the final mechanism depends on levels of the respective signaling and effector proteins.
Present treatment strategies for rheumatoid arthritis include use of disease-modifying antirheuma... more Present treatment strategies for rheumatoid arthritis include use of disease-modifying antirheumatic drugs, but a minority of patients achieve a good response. We aimed to test the hypothesis that an improved outcome can be achieved by employing a strategy of intensive outpatient management of patients with rheumatoid arthritis--for sustained, tight control of disease activity--compared with routine outpatient care. We designed a single-blind, randomised controlled trial in two teaching hospitals. We screened 183 patients for inclusion. 111 were randomly allocated either intensive management or routine care. Primary outcome measures were mean fall in disease activity score and proportion of patients with a good response (defined as a disease activity score <2.4 and a fall in this score from baseline by >1.2). Analysis was by intention-to-treat. One patient withdrew after randomisation and seven dropped out during the study. Mean fall in disease activity score was greater in the intensive group than in the routine group (-3.5 vs -1.9, difference 1.6 [95% CI 1.1-2.1], p<0.0001). Compared with routine care, patients treated intensively were more likely to have a good response (definition, 45/55 [82%] vs 24/55 [44%], odds ratio 5.8 [95% CI 2.4-13.9], p<0.0001) or be in remission (disease activity score <1.6; 36/55 [65%] vs 9/55 [16%], 9.7 [3.9-23.9], p<0.0001). Three patients assigned routine care and one allocated intensive management died during the study; none was judged attributable to treatment. A strategy of intensive outpatient management of rheumatoid arthritis substantially improves disease activity, radiographic disease progression, physical function, and quality of life at no additional cost.
pathway comprise dimers of related proteins (c-Rel, RelA(p65), RelB, p50NF-B1, and p52NF-B2) that... more pathway comprise dimers of related proteins (c-Rel, RelA(p65), RelB, p50NF-B1, and p52NF-B2) that bind consensus B elements within the regulatory regions of target genes (Baldwin, 1996). In most cells, the main pool of Rel/NF-B is sequestered to the cytoplasm by Research inhibitory proteins (IBs). Diverse stimuli, including mito-1G Royal Parade gens, induce Rel/NF-B nuclear import by activating Parkville, Victoria 3050 an IB kinase (IKK) complex that phosphorylates IB Australia proteins (Karin, 1999), targeting them for ubiquitin-2 Department of Surgery dependent proteosome-mediated degradation (White-University of Melbourne side and Israel, 1997). Members of the NFAT family Parkville, Victoria 3050 of transcription factors (NFATC1, NFATC2, NFATC3, Australia NFATC4, NFATC5) also pre-exist in the cytoplasm and 3 John Curtin School of Medical Research are translocated to the nucleus in response to calcium-Australian National University dependent signals that lead to NFAT dephosphorylation Canberra 2601 by calcineurin (Rao et al., 1997). Nuclear NFAT proteins Australian Capital Territory bind regulatory elements within target genes in a coop-Australia erative fashion with other transcription factors, most notably AP-1 proteins (Rao et al., 1997). During T cell activation, different Rel/NF-B dimers Summary enter the nucleus in a temporal fashion. In resting cells, only NF-B1 homodimers are detected in the nucleus Cell growth during the G1 stage of the cell cycle is
Abbreviations used in this paper: EF1␣, elongation factor 1 ␣; EGF, epidermal growth factor; EGFP... more Abbreviations used in this paper: EF1␣, elongation factor 1 ␣; EGF, epidermal growth factor; EGFP, enhanced green fluorescent protein; R26R, ROSA26 reporter.
Human leukaemia inhibitory factor (hLIF) binds to both human and mouse LIF receptors (LIF-R), whi... more Human leukaemia inhibitory factor (hLIF) binds to both human and mouse LIF receptors (LIF-R), while mouse LIF (mLIF) binds only to mouse LIF-R. Moreover, hLIF binds with higher affinity to the mLIF-R than does mLIF. In order to define the regions of the hLIF molecule responsible for species-specific interaction with the hLIF-R and for the unusual high-affinity binding to the mLIF-R, a series of 15 mouse/human LIF hybrids has been generated. Perhaps surprisingly, both of these properties mapped to the same region of the hLIF molecule. The predominant contribution was from residues in the loop linking the third and fourth helices, with lesser contributions from residues in the third helix and the loop connecting the second and third helices in the predicted three-dimensional structure. Since all chimeras retained full biological activity and receptor-binding activity on mouse cells, and there was little variation in the specific biological activity of the purified proteins, it can be ...
Leukemia inhibitory factor (LIF) is a pleiotropic cytokine whose activities appear to be mediated... more Leukemia inhibitory factor (LIF) is a pleiotropic cytokine whose activities appear to be mediated through a single heterodimeric receptor complex. Human LIF (hLIF) can bind to and activate mouse LIF (mLIF) receptors but mLIF is unable to bind to hLIF receptors. Cross-species competition of mLIF and hLIF for binding to the mLIF receptor was found to be dependent on which ligand was used as the radioactive tracer (Layton, M. J., Cross, B. A., Metcalf, D., Ward, L. D., Simpson, R. J., and Nicola, N. A. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 8616-8620), and this phenomenon was investigated in the present study. We found that hLIF bound to the low affinity mLIF receptor with a 100-500-fold higher primary affinity and lower kinetic dissociation rate than mLIF, but both ligands displayed a single rate of ligand dissociation. In contrast, the binding of hLIF to low and high affinity hLIF receptors revealed two classes of binding site. The observed tracer-dependent phenomena suggested th...
Histidine-367 of the human common I chain of the receptor is critical for high-affinity binding o... more Histidine-367 of the human common I chain of the receptor is critical for high-affinity binding of human granulocytemacrophage colony-stimulating factor (growth factor/receptor/ligand binding/functional analysis)
Tks5 (tyrosine kinase substrate with 5 SH3 domains) is an adaptor protein which cooperates with S... more Tks5 (tyrosine kinase substrate with 5 SH3 domains) is an adaptor protein which cooperates with Src tyrosine kinase to promote the formation of protease-enriched, actin-based projections known as invadopodia, which are utilized by invasive cancer cells to degrade the extracellular matrix (ECM). We previously identified a Src-Tks5-Nck pathway which promotes invadopodium formation and ECM proteolysis in melanoma and breast cancer cells. We therefore sought to investigate the significance of Tks5 expression in human cancers. This was undertaken retrospectively through an immunohistochemical evaluation in tissue microarray cores and through data mining of the public database, Oncomine. Here we showed that Tks5 was expressed at higher levels in the microarray cores of breast, colon, lung and prostate cancer tissues compared to the levels in normal tissues. Importantly, mining of Oncomine datasets revealed a strong correlation between Tks5 mRNA overexpression in a number of cancers with i...
Tks5 is a scaffold protein and Src substrate involved in cell migration and matrix degradation th... more Tks5 is a scaffold protein and Src substrate involved in cell migration and matrix degradation through its essential role in invadosome formation and function. We have previously described that Tks5 is fundamental for zebrafish neural crest cell migration in vivo. In the present study, we sought to investigate the function of Tks5 in mammalian development by analyzing mice mutant for sh3pxd2a, the gene encoding Tks5. Homozygous disruption of the sh3pxd2a gene by genetrapping in mouse resulted in neonatal death and the presence of a complete cleft of the secondary palate. Interestingly, embryonic fibroblasts from homozygous gene-trap sh3pxd2a mice lacked only the highest molecular weight band of the characteristic Tks5 triplet observed in protein extracts, leaving the lower molecular weight bands unaffected. This finding, together with the existence of two human Expressed Sequence Tags lacking the first 5 exons of SH3PXD2A, made us hypothesize about the presence of a second alternative transcription start site located in intron V. We performed 59RACE on mouse fibroblasts and isolated a new transcript of the sh3pxd2a gene encoding a novel Tks5 isoform, that we named Tks5b. This novel isoform diverges from the long form of Tks5 in that it lacks the PX-domain, which confers affinity for phosphatidylinositol-3,4-bisphosphate. Instead, Tks5b has a short unique amino terminal sequence encoded by the newly discovered exon 6b; this exon includes a start codon located 29 bp from the 5'-end of exon 6. Tks5b mRNA is expressed in MEFs and all mouse adult tissues analyzed. Tks5b is a substrate for the Src tyrosine kinase and its expression is regulated through the proteasome degradation pathway. Together, these findings indicate the essentiality of the larger Tks5 isoform for correct mammalian development and the transcriptional complexity of the sh3pxd2a gene.
ownstream of kinase (Dok)-related protein (DokR, also known as p56 dok /FRIP/Dok-R) is implicated... more ownstream of kinase (Dok)-related protein (DokR, also known as p56 dok /FRIP/Dok-R) is implicated in cytokine and immunoreceptor signaling in myeloid and T cells. Tyrosine phosphorylation induces DokR to bind the signal relay molecules, RasGTPase-activating protein (RasGAP) and Nck. Here, we have examined the function of DokR during hematopoietic development and the requirement for RasGAP and Nck binding sites in its biological function. Retroviral-mediated expression of DokR in bone marrow cells dramatically inhibited their capacity to form colonies in vitro in response to the cytokines macrophage colony-stimulating factor and stem cell factor, whereas responses to interleukin-3 and granulocyte macrophage D colony-stimulating factor were only weakly affected. When introduced into lethally irradiated mice, hematopoietic cells expressing DokR showed a drastically reduced capacity to repopulate lymphoid tissues. Most notably, DokR dramatically reduced repopulation of the thymus, in part by reducing the number of T cell precursors seeding in the thymus, but equally, through inhibiting the transition of CD4 Ϫ CD8 Ϫ to CD4 ϩ CD8 ϩ T cells. Consequently, the number of mature peripheral T cells was markedly reduced. In contrast, a minimal effect on B cell and myeloid lineage development was observed. Importantly, functional RasGAP and Nck binding sites were found to be essential for the biological effects of DokR in vitro and in vivo.
We describe a method for identifying tyrosine kinase substrates using anti-phosphotyrosine antibo... more We describe a method for identifying tyrosine kinase substrates using anti-phosphotyrosine antibodies to screen tyrosine-phosphorylated cDNA expression libraries. Several potential Src substrates were identified including Fish, which has five SH3 domains and a recently discovered phox homology (PX) domain. Fish is tyrosine-phosphorylated in Src-transformed fibroblasts (suggesting that it is a target of Src in vivo) and in normal cells following treatment with several growth factors. Treatment of cells with cytochalasin D also resulted in rapid tyrosine phosphorylation of Fish, concomitant with activation of Src. These data suggest that Fish is involved in signalling by tyrosine kinases, and imply a specialized role in the actin cytoskeleton.
Mammalian hck, a member of the src family of tyrosine kinases, is expressed predominantly in cell... more Mammalian hck, a member of the src family of tyrosine kinases, is expressed predominantly in cells of the myeloid and B-lymphoid lineages. Using mutational analysis, we have investigated the molecular basis of two immunoreactive forms of murine hck of 56 and 59 kDa found in numerous hemopoietic cell types. Our results indicate that translation of murine p59hck initiates from a CTG codon located 21 codons 5' of an ATG that is utilized to generate p56hck. We provide evidence that two human hck isoforms are generated by the same mechanism. Subcellular fractionation studies reveal that while p59hck and pS6'ck are associated with membranes of various murine B-lymphoid and myeloid cell lines, p59hck alone is also located in the cytosol. In contrast to membrane-associated p59hck, which is metabolically labeled with [3HJmyristic acid and exhibits amphiphilic properties in Triton X-114 detergent, cytosolic p59hck is hydrophilic, suggesting that it is not acylated. Possible mechanisms are proposed to account for these observations.
Several diverse proteins are linked genetically/pathologically to neurodegeneration in amyotrophi... more Several diverse proteins are linked genetically/pathologically to neurodegeneration in amyotrophic lateral sclerosis (ALS) including SOD1, TDP-43 and FUS. Using a variety of cellular and biochemical techniques, we demonstrate that ALS-associated mutant TDP-43, FUS and SOD1 inhibit protein transport between the endoplasmic reticulum (ER) and Golgi apparatus in neuronal cells. ER-Golgi transport was also inhibited in embryonic cortical and motor neurons obtained from a widely used animal model (SOD1 G93A mice), validating this mechanism as an early event in disease. Each protein inhibited transport by distinct mechanisms, but each process was dependent on Rab1. Mutant TDP-43 and mutant FUS both inhibited the incorporation of secretory protein cargo into COPII vesicles as they bud from the ER, and inhibited transport from ER to the ER-Golgi intermediate (ERGIC) compartment. TDP-43 was detected on the cytoplasmic face of the ER membrane, whereas FUS was present within the ER, suggesting that transport is inhibited from the cytoplasm by mutant TDP-43, and from the ER by mutant FUS. In contrast, mutant SOD1 destabilised microtubules and inhibited transport from the ERGIC compartment to Golgi, but not from ER to ERGIC. Rab1 performs multiple roles in ER-Golgi transport, and over-expression of Rab1 restored ER-Golgi transport, and prevented ER stress, mSOD1 inclusion formation and induction of apoptosis, in cells expressing mutant TDP-43, FUS or SOD1. Rab1 also co-localised extensively with mutant TDP-43, FUS and SOD1 in neuronal cells, and Rab1 formed inclusions in motor neurons of spinal cords from sporadic ALS patients, which were positive for ubiquitinated TDP-43, implying that Rab1 is misfolded and dysfunctional in sporadic disease. These results demonstrate that ALS-mutant forms of TDP-43, FUS, and SOD1 all perturb protein transport in the early secretory pathway, between ER and Golgi compartments. These data also imply that restoring Rab1mediated ER-Golgi transport is a novel therapeutic target in ALS.
Mammalian hck, a member of the src family of tyrosine kinases, is expressed predominantly in cell... more Mammalian hck, a member of the src family of tyrosine kinases, is expressed predominantly in cells of the myeloid and B-lymphoid lineages. Using mutational analysis, we have investigated the molecular basis of two immunoreactive forms of murine hck of 56 and 59 kDa found in numerous hemopoietic cell types. Our results indicate that translation of murine p59hck initiates from a CTG codon located 21 codons 5' of an ATG that is utilized to generate p56hck. We provide evidence that two human hck isoforms are generated by the same mechanism. Subcellular fractionation studies reveal that while p59hck and p56hck are associated with membranes of various murine B-lymphoid and myeloid cell lines, p59hck alone is also located in the cytosol. In contrast to membrane-associated p59hck, which is metabolically labeled with [3H]myristic acid and exhibits amphiphilic properties in Triton X-114 detergent, cytosolic p59hck is hydrophilic, suggesting that it is not acylated. Possible mechanisms are...
To examine the effect of waiting times on the health status of patients referred for a non-urgent... more To examine the effect of waiting times on the health status of patients referred for a non-urgent rheumatology opinion. The study was a randomized controlled clinical study evaluating a 'fast track' appointment with a 6-week target waiting time against an 'ordinary' appointment in the main city out-patient clinic of the rheumatology service for the Lothian and Borders region (population approximately 1 million). Health status was measured using the SF12 physical and mental summary component T-scores and pain was measured with a 100 mm visual analogue pain scale. Secondary outcomes were health utility and perceived health both measured with the EuroQol instrument, mental health measured with the Hospital Anxiety and Depression scale, disability with the modified Health Assessment Questionnaire and economic costs measured from a societal perspective. Mean waiting times were 43 days (sigma = +/-16) and 105 days (sigma = +/-51) for 'fast track' and 'ordinary&...
The structure and function of the promoter region and exon 1 of the murine hck gene have been cha... more The structure and function of the promoter region and exon 1 of the murine hck gene have been characterized in detail. RNase protection analysis has established that hck transcripts initiate from heterogeneous start sites located within the hck gene. Fusion gene constructs containing hck 5'-flanking sequences and the bacterial Neor gene have been introduced into the hematopoietic cell lines FDC-P1 and WEHI-265 by using a self-inactivating retroviral vector. The transcriptional start sites of the fusion gene are essentially identical to those of the endogenous hck gene. Analysis of infected WEHI-265 cell lines treated with bacterial lipopolysaccharide (LPS) reveals a 3- to 5-fold elevation in the levels of endogenous hck mRNA and a 1.4- to 2.6-fold increase in the level of Neor fusion gene transcripts, indicating that hck 5'-flanking sequences are capable of conferring LPS responsiveness on the Neor gene. The 5'-flanking region of the hck gene contains sequences similar t...
Two lyn proteins of 56 and 53 kDa have been observed in immunoprecipitates from a variety of muri... more Two lyn proteins of 56 and 53 kDa have been observed in immunoprecipitates from a variety of murine and human cell lines and tissues. We report the cloning and nucleotide sequence of two distinct murine lyn cDNAs isolated from an FDC-P1 cDNA library. One of the cDNAs, designated lyn11, encodes a protein of 56 kDa which shares 96% similarity with human lyn. The other cDNA, designated lyn12, encodes a protein of 53 kDa. The proteins differ in the presence or absence of a 21-amino-acid sequence located 24 amino acids C terminal of the translational initiation codon. Using RNase protection analysis, we have identified mRNAs corresponding to both cDNAs in murine cell lines and tissues. Sequence analysis of murine genomic clones suggests that the distinct mRNAs are alternatively spliced transcripts derived from a single gene. Expression of both cDNAs in COS cells leads to the production of lyn proteins with the same molecular weight as the two forms of lyn proteins immunoprecipitated from...
We have examined the role of tyrosine phosphorylation during the course of macrophage activation.... more We have examined the role of tyrosine phosphorylation during the course of macrophage activation. Initial experiments indicated that vanadate, a known phosphotyrosine phosphatase inhibitor, enhanced the phorbol 12-myristate 13-acetate (PMA)-triggered respiratory burst and potentiated the priming effects of bacterial lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma), suggesting that tyrosine phosphorylation may be important in these end cell functions. As src-related kinases have been implicated in the activation of cells of other haemopoietic lineages, we examined the relationship between the activity of two such kinases, hck and lyn, and priming of the respiratory burst. We found that the level of hck and lyn is increased following exposure of bone marrow-derived macrophages (BMM) to LPS or IFN-gamma. The induction of both of these kinases follows similar kinetics with maximal activity occurring at 24-48 h. Interestingly, the kinetics of induction of hck and lyn kinase acti...
Both receptor-interacting protein kinase 1 (RIPK1) and RIPK3 can signal cell death following deat... more Both receptor-interacting protein kinase 1 (RIPK1) and RIPK3 can signal cell death following death receptor ligation. To study the requirements for RIPK-triggered cell death in the absence of death receptor signaling, we engineered inducible versions of RIPK1 and RIPK3 that can be activated by dimerization with the antibiotic coumermycin. In the absence of TNF or other death ligands, expression and dimerization of RIPK1 was sufficient to cause cell death by caspase- or RIPK3-dependent mechanisms. Dimerized RIPK3 induced cell death by an MLKL-dependent mechanism but, surprisingly, also induced death mediated by FADD, caspase 8 and RIPK1. Catalytically active RIPK3 kinase domains were essential for MLKL-dependent but not for caspase 8-dependent death. When RIPK1 or RIPK3 proteins were dimerized, the mode of cell death was determined by the availability of downstream molecules such as FADD, caspase 8 and MLKL. These observations imply that rather than a 'switch' operating between the two modes of cell death, the final mechanism depends on levels of the respective signaling and effector proteins.
Present treatment strategies for rheumatoid arthritis include use of disease-modifying antirheuma... more Present treatment strategies for rheumatoid arthritis include use of disease-modifying antirheumatic drugs, but a minority of patients achieve a good response. We aimed to test the hypothesis that an improved outcome can be achieved by employing a strategy of intensive outpatient management of patients with rheumatoid arthritis--for sustained, tight control of disease activity--compared with routine outpatient care. We designed a single-blind, randomised controlled trial in two teaching hospitals. We screened 183 patients for inclusion. 111 were randomly allocated either intensive management or routine care. Primary outcome measures were mean fall in disease activity score and proportion of patients with a good response (defined as a disease activity score <2.4 and a fall in this score from baseline by >1.2). Analysis was by intention-to-treat. One patient withdrew after randomisation and seven dropped out during the study. Mean fall in disease activity score was greater in the intensive group than in the routine group (-3.5 vs -1.9, difference 1.6 [95% CI 1.1-2.1], p<0.0001). Compared with routine care, patients treated intensively were more likely to have a good response (definition, 45/55 [82%] vs 24/55 [44%], odds ratio 5.8 [95% CI 2.4-13.9], p<0.0001) or be in remission (disease activity score <1.6; 36/55 [65%] vs 9/55 [16%], 9.7 [3.9-23.9], p<0.0001). Three patients assigned routine care and one allocated intensive management died during the study; none was judged attributable to treatment. A strategy of intensive outpatient management of rheumatoid arthritis substantially improves disease activity, radiographic disease progression, physical function, and quality of life at no additional cost.
pathway comprise dimers of related proteins (c-Rel, RelA(p65), RelB, p50NF-B1, and p52NF-B2) that... more pathway comprise dimers of related proteins (c-Rel, RelA(p65), RelB, p50NF-B1, and p52NF-B2) that bind consensus B elements within the regulatory regions of target genes (Baldwin, 1996). In most cells, the main pool of Rel/NF-B is sequestered to the cytoplasm by Research inhibitory proteins (IBs). Diverse stimuli, including mito-1G Royal Parade gens, induce Rel/NF-B nuclear import by activating Parkville, Victoria 3050 an IB kinase (IKK) complex that phosphorylates IB Australia proteins (Karin, 1999), targeting them for ubiquitin-2 Department of Surgery dependent proteosome-mediated degradation (White-University of Melbourne side and Israel, 1997). Members of the NFAT family Parkville, Victoria 3050 of transcription factors (NFATC1, NFATC2, NFATC3, Australia NFATC4, NFATC5) also pre-exist in the cytoplasm and 3 John Curtin School of Medical Research are translocated to the nucleus in response to calcium-Australian National University dependent signals that lead to NFAT dephosphorylation Canberra 2601 by calcineurin (Rao et al., 1997). Nuclear NFAT proteins Australian Capital Territory bind regulatory elements within target genes in a coop-Australia erative fashion with other transcription factors, most notably AP-1 proteins (Rao et al., 1997). During T cell activation, different Rel/NF-B dimers Summary enter the nucleus in a temporal fashion. In resting cells, only NF-B1 homodimers are detected in the nucleus Cell growth during the G1 stage of the cell cycle is
Abbreviations used in this paper: EF1␣, elongation factor 1 ␣; EGF, epidermal growth factor; EGFP... more Abbreviations used in this paper: EF1␣, elongation factor 1 ␣; EGF, epidermal growth factor; EGFP, enhanced green fluorescent protein; R26R, ROSA26 reporter.
Human leukaemia inhibitory factor (hLIF) binds to both human and mouse LIF receptors (LIF-R), whi... more Human leukaemia inhibitory factor (hLIF) binds to both human and mouse LIF receptors (LIF-R), while mouse LIF (mLIF) binds only to mouse LIF-R. Moreover, hLIF binds with higher affinity to the mLIF-R than does mLIF. In order to define the regions of the hLIF molecule responsible for species-specific interaction with the hLIF-R and for the unusual high-affinity binding to the mLIF-R, a series of 15 mouse/human LIF hybrids has been generated. Perhaps surprisingly, both of these properties mapped to the same region of the hLIF molecule. The predominant contribution was from residues in the loop linking the third and fourth helices, with lesser contributions from residues in the third helix and the loop connecting the second and third helices in the predicted three-dimensional structure. Since all chimeras retained full biological activity and receptor-binding activity on mouse cells, and there was little variation in the specific biological activity of the purified proteins, it can be ...
Leukemia inhibitory factor (LIF) is a pleiotropic cytokine whose activities appear to be mediated... more Leukemia inhibitory factor (LIF) is a pleiotropic cytokine whose activities appear to be mediated through a single heterodimeric receptor complex. Human LIF (hLIF) can bind to and activate mouse LIF (mLIF) receptors but mLIF is unable to bind to hLIF receptors. Cross-species competition of mLIF and hLIF for binding to the mLIF receptor was found to be dependent on which ligand was used as the radioactive tracer (Layton, M. J., Cross, B. A., Metcalf, D., Ward, L. D., Simpson, R. J., and Nicola, N. A. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 8616-8620), and this phenomenon was investigated in the present study. We found that hLIF bound to the low affinity mLIF receptor with a 100-500-fold higher primary affinity and lower kinetic dissociation rate than mLIF, but both ligands displayed a single rate of ligand dissociation. In contrast, the binding of hLIF to low and high affinity hLIF receptors revealed two classes of binding site. The observed tracer-dependent phenomena suggested th...
Histidine-367 of the human common I chain of the receptor is critical for high-affinity binding o... more Histidine-367 of the human common I chain of the receptor is critical for high-affinity binding of human granulocytemacrophage colony-stimulating factor (growth factor/receptor/ligand binding/functional analysis)
Tks5 (tyrosine kinase substrate with 5 SH3 domains) is an adaptor protein which cooperates with S... more Tks5 (tyrosine kinase substrate with 5 SH3 domains) is an adaptor protein which cooperates with Src tyrosine kinase to promote the formation of protease-enriched, actin-based projections known as invadopodia, which are utilized by invasive cancer cells to degrade the extracellular matrix (ECM). We previously identified a Src-Tks5-Nck pathway which promotes invadopodium formation and ECM proteolysis in melanoma and breast cancer cells. We therefore sought to investigate the significance of Tks5 expression in human cancers. This was undertaken retrospectively through an immunohistochemical evaluation in tissue microarray cores and through data mining of the public database, Oncomine. Here we showed that Tks5 was expressed at higher levels in the microarray cores of breast, colon, lung and prostate cancer tissues compared to the levels in normal tissues. Importantly, mining of Oncomine datasets revealed a strong correlation between Tks5 mRNA overexpression in a number of cancers with i...
Tks5 is a scaffold protein and Src substrate involved in cell migration and matrix degradation th... more Tks5 is a scaffold protein and Src substrate involved in cell migration and matrix degradation through its essential role in invadosome formation and function. We have previously described that Tks5 is fundamental for zebrafish neural crest cell migration in vivo. In the present study, we sought to investigate the function of Tks5 in mammalian development by analyzing mice mutant for sh3pxd2a, the gene encoding Tks5. Homozygous disruption of the sh3pxd2a gene by genetrapping in mouse resulted in neonatal death and the presence of a complete cleft of the secondary palate. Interestingly, embryonic fibroblasts from homozygous gene-trap sh3pxd2a mice lacked only the highest molecular weight band of the characteristic Tks5 triplet observed in protein extracts, leaving the lower molecular weight bands unaffected. This finding, together with the existence of two human Expressed Sequence Tags lacking the first 5 exons of SH3PXD2A, made us hypothesize about the presence of a second alternative transcription start site located in intron V. We performed 59RACE on mouse fibroblasts and isolated a new transcript of the sh3pxd2a gene encoding a novel Tks5 isoform, that we named Tks5b. This novel isoform diverges from the long form of Tks5 in that it lacks the PX-domain, which confers affinity for phosphatidylinositol-3,4-bisphosphate. Instead, Tks5b has a short unique amino terminal sequence encoded by the newly discovered exon 6b; this exon includes a start codon located 29 bp from the 5'-end of exon 6. Tks5b mRNA is expressed in MEFs and all mouse adult tissues analyzed. Tks5b is a substrate for the Src tyrosine kinase and its expression is regulated through the proteasome degradation pathway. Together, these findings indicate the essentiality of the larger Tks5 isoform for correct mammalian development and the transcriptional complexity of the sh3pxd2a gene.
ownstream of kinase (Dok)-related protein (DokR, also known as p56 dok /FRIP/Dok-R) is implicated... more ownstream of kinase (Dok)-related protein (DokR, also known as p56 dok /FRIP/Dok-R) is implicated in cytokine and immunoreceptor signaling in myeloid and T cells. Tyrosine phosphorylation induces DokR to bind the signal relay molecules, RasGTPase-activating protein (RasGAP) and Nck. Here, we have examined the function of DokR during hematopoietic development and the requirement for RasGAP and Nck binding sites in its biological function. Retroviral-mediated expression of DokR in bone marrow cells dramatically inhibited their capacity to form colonies in vitro in response to the cytokines macrophage colony-stimulating factor and stem cell factor, whereas responses to interleukin-3 and granulocyte macrophage D colony-stimulating factor were only weakly affected. When introduced into lethally irradiated mice, hematopoietic cells expressing DokR showed a drastically reduced capacity to repopulate lymphoid tissues. Most notably, DokR dramatically reduced repopulation of the thymus, in part by reducing the number of T cell precursors seeding in the thymus, but equally, through inhibiting the transition of CD4 Ϫ CD8 Ϫ to CD4 ϩ CD8 ϩ T cells. Consequently, the number of mature peripheral T cells was markedly reduced. In contrast, a minimal effect on B cell and myeloid lineage development was observed. Importantly, functional RasGAP and Nck binding sites were found to be essential for the biological effects of DokR in vitro and in vivo.
We describe a method for identifying tyrosine kinase substrates using anti-phosphotyrosine antibo... more We describe a method for identifying tyrosine kinase substrates using anti-phosphotyrosine antibodies to screen tyrosine-phosphorylated cDNA expression libraries. Several potential Src substrates were identified including Fish, which has five SH3 domains and a recently discovered phox homology (PX) domain. Fish is tyrosine-phosphorylated in Src-transformed fibroblasts (suggesting that it is a target of Src in vivo) and in normal cells following treatment with several growth factors. Treatment of cells with cytochalasin D also resulted in rapid tyrosine phosphorylation of Fish, concomitant with activation of Src. These data suggest that Fish is involved in signalling by tyrosine kinases, and imply a specialized role in the actin cytoskeleton.
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Papers by Peter Lock