Papers by Delphine FESSART
Biochemical and Biophysical Research Communications, Jan 19, 2007
International journal of cell biology, 2011
The process by which G protein-coupled receptors (GPCRs) are internalized through the clathrin-co... more The process by which G protein-coupled receptors (GPCRs) are internalized through the clathrin-coated vesicles involves interactions of multifunctional adaptor proteins. These interactions are tightly controlled by phosphorylation and dephosphorylation mechanisms resulting in the regulation of receptor endocytosis. However, the identities of the kinases involved in this process remained largely unknown until recently. This paper discusses advances in our knowledge of the important role played by protein phosphorylation in the regulation of the endocytic machinery and how phosphorylation controls the coated vesicle cycle.
Annual Research & Review in Biology, 2014
Pulmonary arterial hypertension (PAH) is characterized by an increase resistance of the vascular ... more Pulmonary arterial hypertension (PAH) is characterized by an increase resistance of the vascular wall from pulmonary arteries leading to vascular lumen occlusion, right ventricular failure, and death. PAH has been described for many years, as a cardiovascular disease affecting the lungs. Whatever the initial cause, pulmonary arterial hypertension involves the vasoconstriction of blood vessels connected to and within the lungs. In addition, the increased workload of the heart causes hypertrophy of the right ventricle, making the heart less able to pump blood through the lungs, causing right heart failure. Recently several groups have demonstrated that PAH is a disease of excess proliferation and impaired apoptosis similar to neoplasia. Although the fundamental cause remains elusive, many predisposing and disease-modifying abnormalities occur, including endothelial injury/dysfunction, bone morphogenetic protein receptor-2 gene mutations, decreased expression of the K+ channel (Kv1.5), transcription factor activation [hypoxia-inducible factor-1 (HIF-1 )], expression of survivin, and increased expression/activity of both serotonin transporters and platelet-derived growth factor receptors. Together, these abnormalities create a cancer-like, proliferative, apoptosis-resistant phenotype. From these observations, it has been established some similarities between PAH and cancer. Therefore, in this review, we will discuss the essential alterations in pulmonary arterial hypertension as compared to cancer cell which has been alluded to as the "cancer
Transplantation Proceedings, 2011
Background. In the current practice of lung transplantation, donor and recipient genders are neit... more Background. In the current practice of lung transplantation, donor and recipient genders are neither directly considered nor matched. However, some data have suggested a possible effect of gender combinations on survival following lung transplantation. Methods. A total of 249 adult lung transplant recipients at a single center between February 1988 and December 2008, were analyzed retrospectively for donor-recipient gender matching. We compared the mortality by calculating one-term survival rates after transplantation using the Kaplan-Meier method with comparisons using the log-rank (Mantel-Cox) test. Statistical significance of the mean effects of size matching was assessed by paired Student t tests and Wilcoxon signed rank tests. Results. Kaplan-Meier survival analysis shown that male compared to female recipients did not have an effect on outcomes after lung transplantation at 5 years (P ϭ .5379), 10 years (P ϭ .107), 15 years (P ϭ .0841), 20 years (P ϭ .0711). No effect of gender on lung transplantation outcomes was observed with donor-recipient gender mismatches at 5 years (P ϭ .1804), 10 years (P ϭ .1457), 15 years (P ϭ .0731), or 20 years (P ϭ .0629). Similarly, no differences were observed for each gender combination. The degree of size matching was defined as the ratio of donor-to-recipient predicted total lung capacity. The ratios were similar for the donor-recipient gender match and significantly different for the donorrecipient gender mismatch. Conclusions. These analyses suggested that gender was not a significant independent risk factor affecting survival after lung transplantation. Size mismatch caused by gender mismatch did not increase mortality.
Oncogene, 2010
Overexpression of Ras G12V in primary cells induces a permanent growth arrest called oncogene-ind... more Overexpression of Ras G12V in primary cells induces a permanent growth arrest called oncogene-induced senescence (OIS) that serves as a fail-safe mechanism against malignant transformation. We have performed a genomewide small interfering RNA (siRNA) screen and a microRNA (miRNA) screen to identify mediators of OIS and show that siRNA-mediated knockdown of p21 Waf1/Cip1 rescues from Ras G12V -induced senescence in human mammary epithelial cells (HMECs). Moreover, we isolated a total of 28 miRNAs that prevented Ras G12Vinduced growth arrest, among which all of the miR-106b family members were present. In addition, we obtained a number of hits, miR-130b, miR-302a, miR-302b, miR302c, miR-302d, miR-512-3p and miR-515-3p with seed sequences very similar to miR-106b family members. We show that overexpression of all these miRNAs rescues HMECs from Ras G12V -induced senescence by prevention of Ras G12V -induced upregulation of p21 Waf1/Cip1 . Our results establish an important role for the cell cycle inhibitor p21 Waf1/Cip1 in growth control of HMECs and extend the repertoire of miRNAs that modulate the activity of this tumour suppressor.
Molecular Endocrinology, 2005
Abbreviations: AP-1/2, clathrin adaptor protein 1 and 2; Ang II, angiotensin II; AT1R, angiotensi... more Abbreviations: AP-1/2, clathrin adaptor protein 1 and 2; Ang II, angiotensin II; AT1R, angiotensin II type 1 receptor; ß2AR, ß2-adrenergic receptor; BSA, bovine serum albumin;
Journal of Molecular and Cellular Cardiology, 2014
The development of right heart failure (RHF) is characterized by alterations of right ventricle (... more The development of right heart failure (RHF) is characterized by alterations of right ventricle (RV) structure and function, but the mechanisms of RHF remain still unknown. Thus, understanding the RHF is essential for improved therapies. Therefore, identification by quantitative proteomics of targets specific to RHF may have therapeutic benefits to identify novel potential therapeutic targets. The objective of this study was to analyze the molecular mechanisms changing RV function in the diseased RHF and thus, to identify novel potential therapeutic targets. For this, we have performed differential proteomic analysis of whole RV proteins using two experimental rat models of RHF. Differential protein expression was observed for hundred twenty six RV proteins including proteins involved in structural constituent of cytoskeleton, motor activity, structural molecule activity, cytoskeleton protein binding and microtubule binding. Interestingly, further analysis of down-regulated proteins, reveals that both protein and gene expressions of proteasome subunits were drastically decreased in RHF, which was accompanied by an increase of ubiquitinated proteins. Interestingly, the proteasomal activities chymotrypsin and caspase-like were decreased whereas trypsin-like activity was maintained. In conclusion, this study revealed the involvement of ubiquitin-proteasome system (UPS) in RHF. Three deregulated mechanisms were discovered: (1) decreased gene and protein expressions of proteasome subunits, (2) decreased specific activity of proteasome; and (3) a specific accumulation of ubiquitinated proteins. This modulation of UPS of RV may provide a novel therapeutic avenue for restoration of cardiac function in the diseased RHF.
Journal of Cell Science, 2007
Beta-arrestins are known to act as endocytic adaptors by recruiting the clathrin adaptor protein ... more Beta-arrestins are known to act as endocytic adaptors by recruiting the clathrin adaptor protein 2 (AP-2) complex to G-protein-coupled receptors (GPCRs), linking them to clathrin-coated pits (CCPs) for internalization. They also act as signaling molecules connecting GPCRs to different downstream effectors. We have previously shown that stimulation of the angiotensin II (Ang II) type 1 receptor (AGTR1, hereafter referred to as AT1R), a member of the GPCR family, promotes the formation of a complex between beta-arrestin, the kinase Src and AP-2. Here, we report that formation of such a complex is involved in the AT1R-mediated tyrosine phosphorylation of beta2-adaptin, the subunit of AP-2 involved in binding beta-arrestin. We identify a crucial tyrosine residue in the ear domain of beta2-adaptin and show in vitro that the phosphorylation of this site regulates the interaction between beta-arrestin and beta2-adaptin. Using fluorescently tagged proteins combined with resonance energy transfer and image cross-correlation spectroscopy approaches, we show in live cells that beta2-adaptin phosphorylation is an important regulatory process for the dissociation of beta-arrestin-AP-2 complexes in CCPs. Finally, we show that beta2-adaptin phosphorylation is involved in the early steps of receptor internalization. Our findings not only unveil beta2-adaptin as a new Src target during AT1R internalization, but also support the role of receptor-mediated signaling in the control of clathrin-dependent endocytosis of receptors.
Journal of Biological Chemistry, 2007
The most widely studied pathway underlying agonist-promoted internalization of G protein-coupled ... more The most widely studied pathway underlying agonist-promoted internalization of G protein-coupled receptors (GPCRs) involves -arrestin and clathrin-coated pits. However, both -arrestinand clathrin-independent processes have also been reported. Classically, the endocytic routes are characterized using pharmacological inhibitors and various dominant negative mutants, resulting sometimes in conflicting results and interpretational difficulties. Here, taking advantage of the fact that -arrestin binding to the 2 subunit of the clathrin adaptor AP-2 (2-adaptin) is needed for the -arrestin-mediated targeting of GPCRs to clathrin-coated pits, we developed a bioluminescence resonance energy transfer-based approach directly assessing the molecular steps involved in the endocytosis of GPCRs in living cells. For 10 of the 12 receptors tested, including some that were previously suggested to internalize via clathrinindependent pathways, agonist stimulation promoted -arrestin 1 and 2 interaction with 2-adaptin, indicating a -arrestinand clathrin-dependent endocytic process. Detailed analyses of -arrestin interactions with both the receptor and 2-adaptin also allowed us to demonstrate that recruitment of -arrestins to the receptor and the ensuing conformational changes are the leading events preceding AP-2 engagement and subsequent clathrin-mediated endocytosis. Among the receptors tested, only the endothelin A and B receptors failed to promote interaction between -arrestins and 2-adaptin. However, both receptors recruited -arrestins upon agonist stimulation, suggesting a -arrestin-dependent but clathrin-independent route of internalization for these two receptors. In addition to providing a new tool to dissect the molecular events involved in GPCR endocytosis, the bioluminescence resonance energy transfer-based -arrestin/2-adaptin interaction assay represents a novel biosensor to assess receptor activation. 7 The abbreviations used are: GPCR, G protein-coupled receptor; AVP, 8-arginine-vasopressin; AP-21967, synthetic heterodimerizer binding with high affinity to both cyclophilin FKBP and FRB fragments; AT1aR, angiotensin II receptor; 2AR, 2-adrenergic receptor; B2R, bradykinin B2 receptor; BRET, bioluminescence resonance energy transfer; C5a, complement component 5a; C5aR, the complement component C5a receptor; CCR5, CC-chemokine 5 receptor; DMEM, Dulbecco's modified Eagle's medium; dynI(K44A), dominant negative mutant of dynamin I; EP4R, prostaglandin EP4 receptor; ET1, endothelin; ETAR, endothelin A receptor; ETBR, endothelin B receptor; FKBP, cyclophilin fragments; FRB, cyclophilin fragment; G418, Geneticin; GFP, green fluorescent protein; HEK, human embryonic kidney cells; HRP, horseradish peroxidase; M2R, M2 muscarinic receptor; PEI, polyethyleneimine; Rluc, Renilla reniformis luciferase; V1aR, V1a vasopressin receptor; V2R, vasopressin V2 receptor; VIP, vasoactive intestinal peptide 1; VIP1R, vasoactive intestinal peptide 1 receptor; EYFP, enhanced yellow fluorescent protein; PBS, phosphate-buffered saline; ELISA, enzyme-linked immunosorbent assay; HA, hemagglutinin; siRNA, small interference RNA.
European Respiratory Journal, 2013
In the present study, we have developed an in vitro three-dimensional model to differentiate norm... more In the present study, we have developed an in vitro three-dimensional model to differentiate normal lung cells from lung cancer cells in order to study the mechanisms resulting in lung cancer.
Cellular Signalling, 2007
We have previously shown that the ADP-ribosylation factor 6 (ARF6), a small GTP-binding protein, ... more We have previously shown that the ADP-ribosylation factor 6 (ARF6), a small GTP-binding protein, is important for the internalization of several G protein-coupled receptors. Here, we propose to elucidate the molecular steps controlled by ARF6 in the endocytic process of the angiotensin II type 1 receptor (ATR), a model receptor being internalized via the clathrin-coated vesicle pathway. In HEK 293 cells, angiotensin II stimulation leads to the formation of a complex including ARF6, the beta-subunit of AP-2 and the heavy chain of clathrin. In vitro experiments indicate that the interactions between ARF6 and the beta-subunit of AP-2 as well as with the heavy chain of clathrin are direct, and dependent upon the nature of the nucleotide bound to ARF6. beta2-adaptin binds to ARF6-GDP while clathrin preferentially interacts with ARF6 when loaded with GTP. These interactions have an important physiological consequence. Indeed, depletion of ARF6 prevents the agonist-dependent recruitment of beta2-adaptin and clathrin to the activated ATR. Interestingly, in these cells, the plasma membrane redistribution of either beta2-adaptin-GFP or betaarrestin 2-GFP, following Ang II stimulation, is altered. Both proteins are defective in clustering into large punctated structure at the plasma membrane compared to control conditions. Taken together, these results suggest that the cycling of ARF6 between its GDP-and GTP-bound states coordinates the recruitment of AP-2 and clathrin to activated receptors during the endocytic process.
Cancer Letters, 2013
a b s t r a c t P97/CDC-48 is a prominent member of a highly evolutionary conserved Walker casset... more a b s t r a c t P97/CDC-48 is a prominent member of a highly evolutionary conserved Walker cassette -containing AAA + ATPases. It has been involved in numerous cellular processes ranging from the control of protein homeostasis to membrane trafficking through the intervention of specific accessory proteins. Expression of p97/CDC-48 in cancers has been correlated with tumor aggressiveness and prognosis, however the precise underlying molecular mechanisms remain to be characterized. Moreover p97/CDC-48 inhibitors were developed and are currently under intense investigation as anticancer drugs. Herein, we discuss the role of p97/CDC-48 in cancer development and its therapeutic potential in tumor cell biology.
Biochemical and Biophysical Research Communications, 2007
Apoptosis, 2007
The endoplasmic reticulum (ER) is the cellular compartment where proteins enter the secretory pat... more The endoplasmic reticulum (ER) is the cellular compartment where proteins enter the secretory pathway, undergo post-translational modifications and acquire a correct conformation. If these functions are chronically altered, specific ER stress signals are triggered to promote cell death through the intrinsic apoptotic pathway. Here, we show that tunicamycin causes significant alteration of calnexin sub-cellular distribution in MCF-7 cells. Interestingly, this correlates with the absence of both tunicamycin-induced calnexin phosphorylation as well as tunicamycin-induced cell death. Under these conditions, calnexin-associated Bap31, an ER integral membrane protein, is subjected to a caspase-8 cleavage pattern within a specific sub-compartment of the ER. These results suggest that MCF-7 resistance to ER stress-induced apoptosis is partially mediated by the expression level of calnexin which in turn controls its sub-cellular localization, and its association with Bap31. These data may delineate a resistance mechanism to the ER stress-induced intrinsic apoptotic pathway.
In a genome-wide siRNA analysis of p16 INK4a (p16) modulators, we identify the Hedgehog (Hh) path... more In a genome-wide siRNA analysis of p16 INK4a (p16) modulators, we identify the Hedgehog (Hh) pathway component SUFU and formally demonstrate that Hh signaling promotes mitogenesis by suppression of p16. A fragment of the Hh-responsive GLI2 transcription factor directly binds and inhibits the p16 promoter and senescence is associated with the loss of nuclear GLI2. Hh components partially reside in the primary cilium (PC), and the small fraction of cells in mass culture that elaborate a PC have the lowest expression of p16. Suppression of p16 is effected by both PC-dependent and -independent routes, and ablation of p16 renders cells insensitive to an Hh inhibitor and increases PC formation. These results directly link a well-established developmental mitogenic pathway with a key tumor suppressor and contribute to the molecular understanding of replicative senescence, Hh-mediated oncogenesis, and potentially the role of p16 in aging.
Cellular Signalling, 2005
Beta-arrestins are multifunctional adaptors that bind agonist-activated G protein-coupled recepto... more Beta-arrestins are multifunctional adaptors that bind agonist-activated G protein-coupled receptors (GPCRs), mediate their desensitization and internalization, and control the rate at which receptors recycle back at the plasma membrane ready for subsequent stimulation. The activation of the bradykinin (BK) type 2 receptor (B2R) results in the rapid desensitization and internalization of the receptor. Little is known, however, about the role of beta-arrestin in regulating the intracellular trafficking and the resensitization of the B2R. Using confocal microscopy, we show that BK stimulation of COS-7 cells expressing B2R induces the colocalization of the agonist-activated receptor with beta-arrestin into endosomes. Fluorescent imaging and ligand binding experiments also reveal that upon agonist removal, beta-arrestin rapidly dissociates from B2R into endosomes, and that receptors return back to the plasma membrane, fully competent for reactivating B2R signaling as measured by NO production upon a second BK challenge. However, when the receptor is mutated in its C-terminal domain to increase its avidity for beta-arrestin, B2R remains associated with beta-arrestin into endosomes, and receptors fail to recycle to the plasma membrane postagonist wash. Similarly, the recycling of receptors is prevented when a beta-arrestin mutant exhibiting increased avidity for agonist-bound GPCRs is expressed with B2R. Stabilizing receptor/beta-arrestin complexes into endosomes results in the dampening of the BK-mediated NO production. These results provide evidence for the involvement of beta-arrestin in the intracellular trafficking of B2R, and highlight the importance of receptor recycling in reestablishing B2R signaling.
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Papers by Delphine FESSART