Papers by Suzanne Jackowski
PloS one, 2015
Pantothenate kinase-associated neurodegeneration, PKAN, is an inherited disorder characterized by... more Pantothenate kinase-associated neurodegeneration, PKAN, is an inherited disorder characterized by progressive impairment in motor coordination and caused by mutations in PANK2, a human gene that encodes one of four pantothenate kinase (PanK) isoforms. PanK initiates the synthesis of coenzyme A (CoA), an essential cofactor that plays a key role in energy metabolism and lipid synthesis. Most of the mutations in PANK2 reduce or abolish the activity of the enzyme. This evidence has led to the hypothesis that lower CoA might be the underlying cause of the neurodegeneration in PKAN patients; however, no mouse model of the disease is currently available to investigate the connection between neuronal CoA levels and neurodegeneration. Indeed, genetic and/or dietary manipulations aimed at reducing whole-body CoA synthesis have not produced a desirable PKAN model, and this has greatly hindered the discovery of a treatment for the disease. Cellular CoA levels are tightly regulated by a balance ...
Cell metabolism, Jan 5, 2015
Accumulation of diacylglycerol (DG) in muscle is thought to cause insulin resistance. DG is a pre... more Accumulation of diacylglycerol (DG) in muscle is thought to cause insulin resistance. DG is a precursor for phospholipids, thus phospholipid synthesis could be involved in regulating muscle DG. Little is known about the interaction between phospholipid and DG in muscle; therefore, we examined whether disrupting muscle phospholipid synthesis, specifically phosphatidylethanolamine (PtdEtn), would influence muscle DG content and insulin sensitivity. Muscle PtdEtn synthesis was disrupted by deleting CTP:phosphoethanolamine cytidylyltransferase (ECT), the rate-limiting enzyme in the CDP-ethanolamine pathway, a major route for PtdEtn production. While PtdEtn was reduced in muscle-specific ECT knockout mice, intramyocellular and membrane-associated DG was markedly increased. Importantly, however, this was not associated with insulin resistance. Unexpectedly, mitochondrial biogenesis and muscle oxidative capacity were increased in muscle-specific ECT knockout mice and were accompanied by en...
Biochemical Society transactions, 2014
CoA (coenzyme A) is an essential cofactor that is emerging as a global regulator of energy metabo... more CoA (coenzyme A) is an essential cofactor that is emerging as a global regulator of energy metabolism. Tissue CoA levels are tightly regulated and vary in response to different conditions including nutritional state and diabetes. Recent studies reveal the ability of this cofactor to control the output of key metabolic pathways. CoA regulation is important for the maintenance of metabolic flexibility and glucose homoeostasis.
Biochemical Society Transactions, 2014
In 1945, Fritz Lipmann discovered a heat-stable cofactor required for many enzyme-catalysed acety... more In 1945, Fritz Lipmann discovered a heat-stable cofactor required for many enzyme-catalysed acetylation reactions. He later determined the structure for this acetylation coenzyme, or coenzyme A (CoA), an achievement for which he was awarded the Nobel Prize in 1953. CoA is now firmly embedded in the literature, and in students' minds, as an acyl carrier in metabolic reactions. However, recent research has revealed diverse and important roles for CoA above and beyond intermediary metabolism. As well as participating in direct post-translational regulation of metabolic pathways by protein acetylation, CoA modulates the epigenome via acetylation of histones. The organization of CoA biosynthetic enzymes into multiprotein complexes with different partners also points to close linkages between the CoA pool and multiple signalling pathways. Dysregulation of CoA biosynthesis or CoA thioester homoeostasis is associated with various human pathologies and, although the biochemistry of CoA biosynthesis is highly conserved, there are significant sequence and structural differences between microbial and human biosynthetic enzymes. Therefore the CoA biosynthetic pathway is an attractive target for drug discovery. The purpose of the Coenzyme A and Its Derivatives in Cellular Metabolism and Disease Biochemical Society Focused Meeting was to bring together researchers from around the world to discuss the most recent advances on the influence of CoA, its biosynthetic enzymes and its thioesters in cellular metabolism and diseases and to discuss challenges and opportunities for the future.
Biochemical Society Transactions, 2014
CoA (coenzyme A) is an essential cofactor that is involved in many metabolic processes. CoA is de... more CoA (coenzyme A) is an essential cofactor that is involved in many metabolic processes. CoA is derived from pantothenate in five biosynthetic reactions. The CoA biosynthetic pathway is regulated by PanKs (pantothenate kinases) and four active isoforms are expressed in mammals. The critical physiological functions of the PanKs are revealed by systematic deletion of the Pank genes in mice.
Antimicrobial agents and chemotherapy, 2002
Thiolactomycin (TLM) is an antibiotic that inhibits bacterial type II fatty acid synthesis at the... more Thiolactomycin (TLM) is an antibiotic that inhibits bacterial type II fatty acid synthesis at the condensing enzyme step, and beta-ketoacyl-acyl carrier protein synthase I (FabB) is the relevant target in Escherichia coli. TLM resistance is associated with the upregulation of efflux pumps. Therefore, a tolC knockout mutant (strain ANS1) was constructed to eliminate the contribution of type I secretion systems to TLM resistance. Six independent TLM-resistant clones of strain ANS1 were isolated, and all possessed the same missense mutation in the fabB gene (T1168G) that directed the expression of a mutant protein, FabB(F390V). FabB(F390V) was resistant to TLM in vitro. Leucine is the only other amino acid found at position 390 in nature, and the Staphylococcus aureus FabF protein, which contains this substitution, was sensitive to TLM. Structural modeling predicted that the CG2 methyl group of the valine side chain interfered with the positioning of the C11 methyl on the isoprenoid si...
Biochemical Society Transactions, 2007
The nature of the bilayer motif coupled with the ability of lipids and proteins to diffuse freely... more The nature of the bilayer motif coupled with the ability of lipids and proteins to diffuse freely through this structure is crucial to the viability of cells and their ability to compartmentalize domains contained therein. It seems surprising to find then that biological as well as model membranes exist in a dynamic state of mechanical stress. The stresses within such membranes are surprisingly large, typically reaching up to 50 atm (1 atm=101.325 kPa) at the core of the membrane and vary as a function of depth. The uneven distribution of lateral pressures within monolayer leaflets causes them to bend away from or towards the water interface. This can result in the formation of complex, self-assembled mesophases, many of which occur in vivo. Our knowledge of the principles underlying membrane mechanics has reached the point where we are now able to manipulate them and create nano-structures with reasonable predictability. In addition, they can be used both to explain and control the partitioning of amphipathic proteins on to membranes. The dependence of the dynamics of membrane-bound proteins and the chemical reactivity of amphipathic drug molecules on membrane stresses suggests that Nature itself takes advantage of this. Understanding and manipulating these internal forces will be a key element in creating self-assembled, biocompatible, nanoscale cell-like systems.
Proliferation of a murine macrophage cell line (BAC1.2F5) in response to colony-stimulating facto... more Proliferation of a murine macrophage cell line (BAC1.2F5) in response to colony-stimulating factor 1 (CSF-1) is inhibited by prostaglandin E2 (PGE2)-mediated elevation of intracellular cyclic AMP (cAMP). When BAC1.2F5 cells were growth arrested in early G, by CSF-1 starvation and stimulated to synchronously enter the cell cycle by readdition of growth factor, PGE2 inhibited [3Hlthymidine incorporation when added before mid-Gl, but its addition at later times did not block the onset of S phase. Reversible cell cycle arrest mediated by a cAMP analog required the presence of CSF-1 for cells to initiate DNA synthesis, whereas cells released from an aphidicolin block at the G1/S boundary entered S phase in the absence of CSF-1. PGE2 or cAMP analogs did not block the initial induction of c-myc mRNA by CSF-1 but abolished the CSF-l-dependent expression of c-myc mRNA in the mid-G1 stage of the cell cycle. The cAMP-mediated reduction in c-myc RNA levels was due to decreased c-myc transcription. However, CSF-1-dependent BAC1.2F5 clones infected with a c-myc retrovirus were growth arrested by cAMP analogs despite constitutive c-myc expression. Therefore, the reduction of endogenous c-myc expression by cAMP is neither necessary nor sufficient for growth inhibition. E-series prostaglandins (prostaglandin El [PGE,] and * Corresponding author. (TGF-P) inhibition of keratinocyte growth (39, 40) may be
Advances in Lipobiology, 1996
This chapter focuses on the metabolism of phospholipid acyl moieties including their initial inco... more This chapter focuses on the metabolism of phospholipid acyl moieties including their initial incorporation into phospholipid, metabolic turnover, resynthesis via the acylation of lysophospholipids, and the assimilation of exogenous fatty acids into membrane phospholipids. The only established metabolic cycle for the turnover of membrane phospholipid acyl moieties is the 2-acylglycerophosphoethanolamine (2-acyl-GPE) cycle. This cycle involves the removal of 1-position acyl moieties from PtdEtn and their replacement by 2-acyl-GPE acyltransferase. The rate of acyl group turnover is low, amounting to only 3–5% of the PtdEtn pool per generation. Thus, detection of acyl group turnover in pulse-chase metabolic labeling experiments is technically challenging due to the large amount of PtdEtn in the cell. Although this low rate of turnover may seem insignificant, it may play an essential metabolic role when considered in view of the synthesis of membrane protein components that are three to four orders of magnitude less abundant.
Chemistry and Physics of Lipids, 2008
New Comprehensive Biochemistry, 2002
This chapter describes the bacterial lipid metabolism, membrane systems of bacteria, bacterial fa... more This chapter describes the bacterial lipid metabolism, membrane systems of bacteria, bacterial fatty acid biosynthesis, fatty acyl chain transfer to the membrane, phospholipid biosynthesis, lipid A biosynthesis, phospholipid flippase, degradation of fatty acids and phospholipids, phospholipid turnover, regulation of lipid metabolism, and lipid metabolism in other bacteria. The pathway in most bacteria is catalyzed by a series of discrete proteins: the enzymes of fatty acid synthesis are cytosolic while those of membrane lipid synthesis are mainly integral inner membrane proteins. The differences between the bacterial and mammalian enzymes offer attractive targets for novel antimicrobial drugs, and this has been a driving force behind much of the recent research. Many of the details of the regulation of fatty acid biosynthesis are still to be worked out, including the probable discovery of new transcription factors and new effector molecules. A rapid evolution of techniques for studying the structure and function of membrane proteins will be applied to resolve outstanding issues in bacterial lipid biogenesis.
Biochimica Et Biophysica Acta-molecular and Cell Biology of Lipids, 2007
The synthesis of phosphatidylcholine (PtdCho), the major phospholipid in mammalian cells, is regu... more The synthesis of phosphatidylcholine (PtdCho), the major phospholipid in mammalian cells, is regulated by the CTP:phosphocholine cytidylyltransferase (CCT). Loss of the CCTβ2 isoform expression in mice results in gonadal dysfunction. CCTβ2−/− females exhibit ovarian tissue disorganization with progressive loss of follicle formation and oocyte maturation. Ultrastructure revealed a disrupted association between ova and granulosa cells and disorganized Golgi apparati in oocytes of CCTβ2−/− mice. Probucol is a cholesterol-lowering agent that stimulates the uptake and retention of lipids carried by lipoproteins in peripheral tissues. Probucol therapy significantly lowered both serum cholesterol and PtdCho levels. Probucol therapy increased fertility in the CCTβ2−/− females 100%, although it did not completely correct the phenotype, the morphological abnormalities in the knockout ovaries or itself stimulate CCT activity directly. These data indicated that a deficiency in de novo PtdCho synthesis could be complemented by altering the metabolism of serum lipoproteins, an alternative source for cellular phospholipid.
Chemistry and Physics of Lipids, 2009
Chemistry & Biology, 2010
Pantothenate kinase (PanK) catalyzes the rate-controlling step in coenzyme A (CoA) biosynthesis. ... more Pantothenate kinase (PanK) catalyzes the rate-controlling step in coenzyme A (CoA) biosynthesis. PanK3 is stringently regulated by acetyl-CoA and uses an ordered kinetic mechanism with ATP as the leading substrate. Biochemical analysis of site-directed mutants indicates that pantothenate binds in a tunnel adjacent to the active site that is occupied by the pantothenate moiety of the acetyl-CoA regulator in the PanK3⋅acetyl-CoA binary complex. A high-throughput screen for PanK3 inhibitors and activators was applied to a bioactive compound library. Thiazolidinediones, sulfonylureas and steroids were inhibitors, and fatty acyl-amides and tamoxifen were activators. The PanK3 activators and inhibitors either stimulated or repressed CoA biosynthesis in HepG2/C3A cells. The flexible allosteric acetyl-CoA regulatory domain of PanK3 also binds the substrates, pantothenate and pantetheine, and small molecule inhibitors and activators to modulate PanK3 activity.► PanK3 binds pantothenate within the acetyl-CoA regulatory site ► Thiazolidinediones and sulfonylureas are PanK3 inhibitors ► Tamoxifen and fatty acyl amides are PanK3 activators ► Flexible allosteric acetyl-CoA regulatory domain also binds substrates and small molecular inhibitors and activators
Proceedings of The National Academy of Sciences, 2000
The activity of CTP:phosphocholine cytidylyltransferase, a rate-limiting enzyme in phosphatidylch... more The activity of CTP:phosphocholine cytidylyltransferase, a rate-limiting enzyme in phosphatidylcholine biosynthesis, is modulated by its interaction with lipid bilayers [Kent, C. (1997) Biochim. Biophys. Acta 1348, 79-90]. Its regulation is of central importance in the maintenance of membrane lipid homeostasis. Here we show evidence that the stored curvature elastic stress in the lipid membrane's monolayer modulates the activity of CTP:phosphocholine cytidylyltransferase. Our results show how a purely physical feedback signal could play a key role in the control of membrane lipid synthesis.
Journal of Cellular Biochemistry, 1987
The product of the c-fms proto-oncogene is related to, and possibly identical with, the receptor ... more The product of the c-fms proto-oncogene is related to, and possibly identical with, the receptor for the macrophage colony-stimulating factor, M-CSF (CSF-1). Unlike the product of the v-erbB oncogene, which is a truncated version of the EGF receptor, the glycoprotein encoded by the v-fms oncogene retains an intact extracellular ligand-binding domain so that cells transformed by v-fms express CSF-1 receptors at their surface. Although fibroblasts susceptible to transformation by v-fms generally produce CSF-1, v-fms-mediated transformation does not depend on an exogenous source of the growth factor, and neutralizing antibodies to CSF-1 do not affect the transformed phenotype. An alteration of the v-fms gene product at its extreme carboxyl-terminus represents the major structural difference between it and the c-fms-coded glycoprotein and may affect the tyrosine kinase activity of the v-fms-coded receptor. Consistent with this interpretation, tyrosine phosphorylation of the v-fms products in membranes was observed in the absence of CSF-1 and was not enhanced by addition of the murine growth factor. Cells transformed by v-fms have a constitutively elevated specific activity of a guanir.c nucleotide-dependent, phosphatidylinositol-4,5-diphosphate-specific phospholipase C. We speculate that the tyrosine kinase activity of the v-fms/c-fms gene products may be coupled to this phospholipase C, possibly through a G regulatory protein, thereby increasing phosphatidylinositol turnover and generating the intracellular second messengers diacylglycerol and inositol triphosphatc.
Journal of Biological Chemistry, 2008
CTP:phosphocholine cytidylyltransferase (CCT) is a key ratecontrolling enzyme in the biosynthetic... more CTP:phosphocholine cytidylyltransferase (CCT) is a key ratecontrolling enzyme in the biosynthetic pathway leading to the principle membrane phospholipid, phosphatidylcholine. CCT␣ is the predominant isoform expressed in mammalian cells. To investigate the role of CCT␣ in the development and function of B-lymphocytes, mice with B-lymphocytes that selectively lacked CCT␣ were derived using the CD19-driven Cre/loxP system. When challenged with a T-cell-dependent antigen, the animals harboring CCT␣-deficient B-cells exhibited a hyper-IgM secretion phenotype coupled with a lack of IgG production. The inability of CCT␣ ؊/؊ B-cells to undergo class switch recombination correlated with a proliferation defect in vivo and in vitro in response to antigenic and mitogenic stimuli. Lipopolysaccharide stimulation of CCT␣ ؊/؊ B-cells resulted in an early trigger of the unfolded protein response-mediated splicing of Xbp-1 mRNA, and this was accompanied by accelerated kinetics of IgM secretion and higher incidence of IgM-secreting cells. Thus, the inability of stimulated B-cells to produce enough phosphatidylcholine prevents proliferation and class switch recombination but leads to unfolded protein response activation and a hyper-IgM secretion phenotype.
Chemistry and Physics of Lipids, 2007
Journal of Lipid Research, 2008
This review presents an overview of mammalian phospholipid synthesis and the cellular locations o... more This review presents an overview of mammalian phospholipid synthesis and the cellular locations of the biochemical activities that produce membrane lipid molecular species. The generalized endoplasmic reticulum compartment is a central site for membrane lipid biogenesis, and examples of the emerging relationships between alterations in lipid composition, regulation of membrane lipid biogenesis, and cellular secretory function are discussed.-Fagone, P., and S. Jackowski. Membrane phospholipid synthesis and endoplasmic reticulum function. J. Lipid Res. 2009. 50: S311-S316.
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Papers by Suzanne Jackowski