The overwhelming majority of patients with type 2 diabetes mellitus (T2DM) and related syndromes die from accelerated atherosclerosis. These patients exhibit a striking persistence of postprandial TG-rich lipoproteins, called ?remnants,? in their plasma after each meal. Importantly, remnants have been linked to human cardiovascular events. Because the basis for delayed remnant clearance in T2DM patients has been poorly understood, no therapeutic strategies are available to selectively target these harmful particles. Our laboratory has made a series of fundamental advances in this area. First, we identified the syndecan-1 heparan sulfate proteoglycan (HSPG) as a remnant receptor. Second, using an array, we found dysregulation of exactly one gene that would impair syndecan-1 function in remnant clearance ? namely, sulfatase-2 (Sulf2), which is 10-fold overexpressed in T2DM liver. SULF2 impedes syndecan-1-mediated catabolism of remnants by liver cells. Third, we just published that inhibition of hepatic Sulf2 in vivo flattens plasma TG excursions after corn-oil gavage in T2DM mice. Fourth, we discovered that insulin suppresses SULF2 protein posttranscriptionally, and that this effect becomes insulin-resistant in T2DM liver, related to impaired AKT activation. By focusing on SULF2, we will improve our understanding of postprandial dyslipidemia and facilitate the translation of our work into clinical utility.
Aim 1 : Molecular mechanisms for the normal suppression of sulfatase-2 protein by insulin. Hypothesis 1: Understanding the normal regulation of hepatic SULF2 expression will reveal key nodes that are potential therapeutic targets. Virtually nothing is currently known about how insulin suppresses hepatocyte expression of SULF2. We will investigate SULF2 regulation by working from the insulin receptor and the PI3 kinase-AKT pathway downwards (Aim 1a) and from the SULF2 protein upwards (Aim 1b).
Aim 2 : Novel strategies to correct hepatic SULF2 overexpression in T2DM db/db liver, and hence attenuate postprandial dyslipoproteinemia. Hypothesis 2: Inhibition of SULF2 is a viable therapeutic strategy, and we will take this concept beyond our previous ASO method. Here, we will manipulate in vivo the novel AKT-dependent participants in SULF2 regulation that we identify in Aim 1. Overall, these proposed Aims will substantially advance our molecular understanding and our abilities to correct the devastating health burden from postprandial dyslipoproteinemia in T2DM.
The overwhelming majority of patients with type 2 diabetes mellitus (T2DM) and related syndromes die from accelerated atherosclerosis that arises, in part, from the striking persistence of harmful intestinally derived lipoproteins, called ?remnants,? in their plasma after each meal. In two major advances, we discovered that syndecan-1 mediates the healthy, rapid disposal of remnants by the liver, but T2DM livers overexpress sulfatase-2, a novel inhibitor of syndecan-1. Building on these discoveries, the research in this proposal will substantially advance our molecular understanding and our abilities to correct the devastating health burden from postprandial dyslipoproteinemia in T2DM.
| Chen, Keyang; Wu, Qingsi; Hu, Kongwang et al. (2018) Suppression of Hepatic FLOT1 (Flotillin-1) by Type 2 Diabetes Mellitus Impairs the Disposal of Remnant Lipoproteins via Syndecan-1. Arterioscler Thromb Vasc Biol 38:102-113 |
| Chen, Yan; Li, Guangping; Liu, Yanxia et al. (2016) Translocation of Endogenous Danger Signal HMGB1 From Nucleus to Membrane Microvesicles in Macrophages. J Cell Physiol 231:2319-26 |
| Li, Mingzhen; Li, Chunjun; Liu, Yu et al. (2015) Decreased secretion of adiponectin through its intracellular accumulation in adipose tissue during tobacco smoke exposure. Nutr Metab (Lond) 12:15 |
| Hassing, H Carlijne; Surendran, R Preethi; Derudas, Bruno et al. (2014) SULF2 strongly prediposes to fasting and postprandial triglycerides in patients with obesity and type 2 diabetes mellitus. Obesity (Silver Spring) 22:1309-16 |
