The HXGH motif of CTP:phosphocholine cytidylyltransferase (CCT) is a unifying feature of the cyti... more The HXGH motif of CTP:phosphocholine cytidylyltransferase (CCT) is a unifying feature of the cytidylyltransferase family which has been proposed to function in binding of CTP and catalysis [Veitch, D. P. & Cornell, R. B. (1996) Biochemistry 35, 10743-10750]. Substitution of serine for Gly91 in the HXGH motif of CCT implicates this motif in CTP-binding [Park, Y. S., Gee, P., Sanker, S., Schuster, E. J., Zuiderweg, E. R. & Kent, C. (1997) J. Biol. Chem. 272, 15161]. The model for CTP binding involves hydrogen bond contacts between the histidine imidazole and the CTP phosphate oxygens. We have mutated His89 and His92 to Gly or Ala, which eliminate potential hydrogen bonds, and to Asn or Gln, which conserve these interactions. Mutation to Gly or Ala at both positions, and the H89Q mutation resulted in inactive enzymes. The Vmax of [N89]CT was 100-fold lower than that of wild-type CCT, but CTP binding was not perturbed, suggesting an involvement of His89 in transition-state stabilization...
Lipases and esterases constitute a large category of enzymes. They are ubiquitous in nature, foun... more Lipases and esterases constitute a large category of enzymes. They are ubiquitous in nature, found in bacteria, fungi, and animals. The family members address a wide variety of structurally diverse substrates. Appropriately, a large number of assays have been developed to analyze their activity in vitro. Here, we present an overview of these enzymes, along with protocols for common assays performed in solution. An emphasis is placed on assays for enzymes that can hydrolyze triacylglycerols.
High density lipoproteins (HDL), through activity of the main protein component apolipoprotein A-... more High density lipoproteins (HDL), through activity of the main protein component apolipoprotein A-I (ApoA-I), can reduce the risk of cardiovascular disease (CVD) by removing excess cholesterol from atherosclerotic plaque. In this study, we demonstrate that the bromodomain and extraterminal domain (BET) inhibitor RVX-208 increases ApoA-I gene transcription and protein production in human and primate primary hepatocytes. Accordingly, RVX-208 also significantly increases levels of ApoA-I, HDL-associated cholesterol, and HDL particle number in patients who received the compound in recently completed phase 2b trials SUSTAIN and ASSURE. Moreover, a post-hoc analysis showed lower instances of major adverse cardiac events in patients receiving RVX-208. To understand the effects of RVX-208 on biological processes underlying cardiovascular risk, we performed microarray analyses of human primary hepatocytes and whole blood treated ex vivo. Overall, data showed that RVX-208 raises ApoA-I/HDL and...
Lipases and esterases constitute a large category of enzymes. They are ubiquitous in nature, foun... more Lipases and esterases constitute a large category of enzymes. They are ubiquitous in nature, found in bacteria, fungi, and animals. The family members address a wide variety of structurally diverse substrates. Appropriately, a large number of assays have been developed to analyze their activity in vitro. Here, we present an overview of these enzymes, along with protocols for common assays performed in solution. An emphasis is placed on assays for enzymes that can hydrolyze triacylglycerols.
Diet-induced obesity and its serious consequences such as diabetes, cardiovascular disease, and c... more Diet-induced obesity and its serious consequences such as diabetes, cardiovascular disease, and cancer are rapidly becoming a major global health threat. Therefore, understanding the cellular and molecular mechanisms by which dietary fat causes obesity and diabetes is of paramount importance in order to identify preventive and therapeutic strategies. Increased dietary fat intake results in high plasma levels of triglyceride-rich lipoproteins (TGRL). Tissue uptake of TGRL has been shown to promote glucose intolerance. We generated mice with an adipocyte-specific inactivation of the multifunctional receptor LDL receptor-related protein-1 (LRP1) to determine its role in mediating the effects of TGRL on diet-induced obesity and diabetes. Knockout mice displayed delayed postprandial lipid clearance, reduced body weight, smaller fat stores, lipid-depleted brown adipocytes, improved glucose tolerance, and elevated energy expenditure due to enhanced muscle thermogenesis. We further demonstr...
Targeted deletion of S6 kinase (S6K) 1 in mice leads to higher energy expenditure and improved gl... more Targeted deletion of S6 kinase (S6K) 1 in mice leads to higher energy expenditure and improved glucose metabolism. However, the molecular mechanisms controlling these effects remain to be fully elucidated. Here, we analyze the potential role of dietary lipids in regulating the mTORC1/S6K system. Analysis of S6K phosphorylation in vivo and in vitro showed that dietary lipids activate S6K, and this effect is not dependent upon amino acids. Comparison of male mice lacking S6K1 and 2 (S6K-dko) with wt controls showed that S6K-dko mice are protected against obesity and glucose intolerance induced by a high-fat diet. S6K-dko mice fed a high-fat diet had increased energy expenditure, improved glucose tolerance, lower fat mass gain, and changes in markers of lipid metabolism. Importantly, however, these metabolic phenotypes were dependent upon dietary lipids, with no such effects observed in S6K-dko mice fed a fat-free diet. These changes appear to be mediated via modulation of cellular met...
The HXGH motif of CTP:phosphocholine cytidylyltransferase (CCT) is a unifying feature of the cyti... more The HXGH motif of CTP:phosphocholine cytidylyltransferase (CCT) is a unifying feature of the cytidylyltransferase family which has been proposed to function in binding of CTP and catalysis [Veitch, D. P. & Cornell, R. B. (1996) Biochemistry 35, 10743-10750]. Substitution of serine for Gly91 in the HXGH motif of CCT implicates this motif in CTP-binding [Park, Y. S., Gee, P., Sanker, S., Schuster, E. J., Zuiderweg, E. R. & Kent, C. (1997) J. Biol. Chem. 272, 15161]. The model for CTP binding involves hydrogen bond contacts between the histidine imidazole and the CTP phosphate oxygens. We have mutated His89 and His92 to Gly or Ala, which eliminate potential hydrogen bonds, and to Asn or Gln, which conserve these interactions. Mutation to Gly or Ala at both positions, and the H89Q mutation resulted in inactive enzymes. The Vmax of [N89]CT was 100-fold lower than that of wild-type CCT, but CTP binding was not perturbed, suggesting an involvement of His89 in transition-state stabilization...
Lipases and esterases constitute a large category of enzymes. They are ubiquitous in nature, foun... more Lipases and esterases constitute a large category of enzymes. They are ubiquitous in nature, found in bacteria, fungi, and animals. The family members address a wide variety of structurally diverse substrates. Appropriately, a large number of assays have been developed to analyze their activity in vitro. Here, we present an overview of these enzymes, along with protocols for common assays performed in solution. An emphasis is placed on assays for enzymes that can hydrolyze triacylglycerols.
High density lipoproteins (HDL), through activity of the main protein component apolipoprotein A-... more High density lipoproteins (HDL), through activity of the main protein component apolipoprotein A-I (ApoA-I), can reduce the risk of cardiovascular disease (CVD) by removing excess cholesterol from atherosclerotic plaque. In this study, we demonstrate that the bromodomain and extraterminal domain (BET) inhibitor RVX-208 increases ApoA-I gene transcription and protein production in human and primate primary hepatocytes. Accordingly, RVX-208 also significantly increases levels of ApoA-I, HDL-associated cholesterol, and HDL particle number in patients who received the compound in recently completed phase 2b trials SUSTAIN and ASSURE. Moreover, a post-hoc analysis showed lower instances of major adverse cardiac events in patients receiving RVX-208. To understand the effects of RVX-208 on biological processes underlying cardiovascular risk, we performed microarray analyses of human primary hepatocytes and whole blood treated ex vivo. Overall, data showed that RVX-208 raises ApoA-I/HDL and...
Lipases and esterases constitute a large category of enzymes. They are ubiquitous in nature, foun... more Lipases and esterases constitute a large category of enzymes. They are ubiquitous in nature, found in bacteria, fungi, and animals. The family members address a wide variety of structurally diverse substrates. Appropriately, a large number of assays have been developed to analyze their activity in vitro. Here, we present an overview of these enzymes, along with protocols for common assays performed in solution. An emphasis is placed on assays for enzymes that can hydrolyze triacylglycerols.
Diet-induced obesity and its serious consequences such as diabetes, cardiovascular disease, and c... more Diet-induced obesity and its serious consequences such as diabetes, cardiovascular disease, and cancer are rapidly becoming a major global health threat. Therefore, understanding the cellular and molecular mechanisms by which dietary fat causes obesity and diabetes is of paramount importance in order to identify preventive and therapeutic strategies. Increased dietary fat intake results in high plasma levels of triglyceride-rich lipoproteins (TGRL). Tissue uptake of TGRL has been shown to promote glucose intolerance. We generated mice with an adipocyte-specific inactivation of the multifunctional receptor LDL receptor-related protein-1 (LRP1) to determine its role in mediating the effects of TGRL on diet-induced obesity and diabetes. Knockout mice displayed delayed postprandial lipid clearance, reduced body weight, smaller fat stores, lipid-depleted brown adipocytes, improved glucose tolerance, and elevated energy expenditure due to enhanced muscle thermogenesis. We further demonstr...
Targeted deletion of S6 kinase (S6K) 1 in mice leads to higher energy expenditure and improved gl... more Targeted deletion of S6 kinase (S6K) 1 in mice leads to higher energy expenditure and improved glucose metabolism. However, the molecular mechanisms controlling these effects remain to be fully elucidated. Here, we analyze the potential role of dietary lipids in regulating the mTORC1/S6K system. Analysis of S6K phosphorylation in vivo and in vitro showed that dietary lipids activate S6K, and this effect is not dependent upon amino acids. Comparison of male mice lacking S6K1 and 2 (S6K-dko) with wt controls showed that S6K-dko mice are protected against obesity and glucose intolerance induced by a high-fat diet. S6K-dko mice fed a high-fat diet had increased energy expenditure, improved glucose tolerance, lower fat mass gain, and changes in markers of lipid metabolism. Importantly, however, these metabolic phenotypes were dependent upon dietary lipids, with no such effects observed in S6K-dko mice fed a fat-free diet. These changes appear to be mediated via modulation of cellular met...
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Papers by Dean Gilham