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Mkhize BC, Mosili P, Ngubane PS, Sibiya NH, Khathi A. The Relationship between Renin-Angiotensin-Aldosterone System (RAAS) Activity, Osteoporosis and Estrogen Deficiency in Type 2 Diabetes. Int J Mol Sci 2023; 24:11963. [PMID: 37569338 PMCID: PMC10419188 DOI: 10.3390/ijms241511963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 07/15/2023] [Accepted: 07/21/2023] [Indexed: 08/13/2023] Open
Abstract
Type 2 diabetes (T2D) is associated with a plethora of comorbidities, including osteoporosis, which occurs due to an imbalance between bone resorption and formation. Numerous mechanisms have been explored to understand this association, including the renin-angiotensin-aldosterone system (RAAS). An upregulated RAAS has been positively correlated with T2D and estrogen deficiency in comorbidities such as osteoporosis in humans and experimental studies. Therefore, research has focused on these associations in order to find ways to improve glucose handling, osteoporosis and the downstream effects of estrogen deficiency. Upregulation of RAAS may alter the bone microenvironment by altering the bone marrow inflammatory status by shifting the osteoprotegerin (OPG)/nuclear factor kappa-Β ligand (RANKL) ratio. The angiotensin-converting-enzyme/angiotensin II/Angiotensin II type 1 receptor (ACE/Ang II/AT1R) has been evidenced to promote osteoclastogenesis and decrease osteoblast formation and differentiation. ACE/Ang II/AT1R inhibits the wingless-related integration site (Wnt)/β-catenin pathway, which is integral in bone formation. While a lot of literature exists on the effects of RAAS and osteoporosis on T2D, the work is yet to be consolidated. Therefore, this review looks at RAAS activity in relation to osteoporosis and T2D. This review also highlights the relationship between RAAS activity, osteoporosis and estrogen deficiency in T2D.
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Affiliation(s)
- Bongeka Cassandra Mkhize
- Human Physiology, Health Science, Westville Campus, University of KwaZulu-Natal, Westville 4041, South Africa; (B.C.M.); (P.M.); (P.S.N.)
| | - Palesa Mosili
- Human Physiology, Health Science, Westville Campus, University of KwaZulu-Natal, Westville 4041, South Africa; (B.C.M.); (P.M.); (P.S.N.)
| | - Phikelelani Sethu Ngubane
- Human Physiology, Health Science, Westville Campus, University of KwaZulu-Natal, Westville 4041, South Africa; (B.C.M.); (P.M.); (P.S.N.)
| | | | - Andile Khathi
- Human Physiology, Health Science, Westville Campus, University of KwaZulu-Natal, Westville 4041, South Africa; (B.C.M.); (P.M.); (P.S.N.)
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2
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Mkhize BC, Mosili P, Ngubane PS, Sibiya NH, Khathi A. Diet-induced prediabetes: Effects on the activity of the renin-angiotensin-aldosterone system (RAAS) in selected organs. J Diabetes Investig 2021; 13:768-780. [PMID: 34619025 PMCID: PMC9077724 DOI: 10.1111/jdi.13690] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 09/14/2021] [Accepted: 10/04/2021] [Indexed: 11/30/2022] Open
Abstract
Derangements often observed with type 2 diabetes (T2D) are associated with disturbances in renin-angiotensin-aldosterone system (RAAS) activity. A positive correlation between local RAAS activity and the complications observed in T2D has been noted. However, the detrimental ramifications due to moderate hyperglycemia noted in prediabetes and the affected organ system and mechanistic pathways are not elucidated. Hence, this study investigated the effects of diet-induced prediabetes on RAAS in various organs. MATERIALS AND METHODS Male Sprague-Dawley rats were separated into two groups: non-pre-diabetic (NPD) through exposure to standard rat chow and diet-induced prediabetic (PD) group by exposure to a high-fat high carbohydrate diet for 32 weeks. RAAS activity in the skeletal muscle, adipose tissue, liver, pancreas and heart was determined through the analysis of RAAS components such as; renin, angiotensinogen, angiotensin-converting enzyme (ACE) and angiotensin II type 1 receptor (AT1R) via PCR as well as the quantification of angiotensin II and aldosterone concentration. Furthermore, NADPH oxidase, SOD and GPx1 concentrations were determined in the skeletal muscle, pancreas and heart in addition to the hepatic triglycerides. RESULTS The RAAS components were elevated in the PD group when compared to the NPD. This was further accompanied by increased NADPH oxidase and reduced SOD and GPx1 concentrations in the selected organs, in addition to the elevated hepatic triglycerides concentration in the PD by comparison to NPD. CONCLUSION Due to these observed changes, we suggest that local RAAS activity in the prediabetic state in selected organs elicits the derangements noted in T2D.
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Abstract
Recent advances in the field of glycobiology have exposed a multitude of biological processes that are controlled or influenced by proteoglycans, in both physiological and pathological conditions ranging from early embryonic development, inflammation, and fibrosis to tumor invasion and metastasis. The first part of this article reviews the biosynthesis of proteoglycans and their multifunctional roles in health and disease; the second part of this review focuses on their putative roles in peritoneal homeostasis and peritoneal inflammation and fibrosis in the context of chronic peritoneal dialysis and peritonitis.
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Affiliation(s)
- Susan Yung
- Department of Medicine, University of Hong Kong, Hong Kong
| | - Tak Mao Chan
- Department of Medicine, University of Hong Kong, Hong Kong
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Al-Sharea A, Murphy AJ, Huggins LA, Hu Y, Goldberg IJ, Nagareddy PR. SGLT2 inhibition reduces atherosclerosis by enhancing lipoprotein clearance in Ldlr -/- type 1 diabetic mice. Atherosclerosis 2018. [PMID: 29518749 DOI: 10.1016/j.atherosclerosis.2018.02.028] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND AND AIMS Leukocytosis, particularly monocytosis, has been shown to promote atherosclerosis in both diabetic and non-diabetic mouse models. We previously showed that hyperglycemia independently promotes monocytosis and impairs the resolution of atherosclerosis. Since patients with chronic diabetes often develop dyslipidemia and also have increased risk for atherosclerosis, we sought to examine how controlling blood glucose affects atherosclerosis development in the presence of severe hyperlipidemia. METHODS Diabetes was induced using streptozotocin (STZ) in low density lipoprotein receptor (Ldlr) knockout (Ldlr-/-) mice after which they were fed a high-cholesterol diet for 4 weeks. Control and diabetic mice were treated with vehicle or sodium glucose cotransporter inhibitor (SGLT2i, Phlorizin or Dapagliflozin) for the duration of the diet. RESULTS Induction of diabetes resulted in a dramatic increase in plasma cholesterol (TC) and triglyceride (TG) levels. These mice also exhibited an increased number of circulating monocytes and neutrophils. Monocytosis was driven by increased proliferation of progenitor cells in the bone marrow. Tighter glycemic control by SGLT2i treatment not only reduced monocytosis and atherosclerosis but also improved plasma lipoprotein profile. Interestingly, improved lipoprotein profile was not due to decreased TG synthesis or clearance via low density lipoprotein receptor-related protein (Lrp) 1 or scavenger receptor class B member (Scarb1) pathways, but likely mediated by heparin sulfate proteoglycans (HSPG)-dependent clearance mechanisms in the liver. Further examination of the liver revealed an important role for bile acid transporters (Abcg5, Abcg8) and cytochrome P450 enzymes in the clearance of hepatic cholesterol. CONCLUSIONS These data suggest that tighter glycemic control in diabetes can improve lipoprotein clearance exclusive of Ldlr, likely via HSPG and bile acid pathways, and has an overall net positive effect on atherosclerosis.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily G, Member 5/metabolism
- ATP Binding Cassette Transporter, Subfamily G, Member 8/metabolism
- Animals
- Atherosclerosis/blood
- Atherosclerosis/genetics
- Atherosclerosis/pathology
- Atherosclerosis/prevention & control
- Benzhydryl Compounds/pharmacology
- Biomarkers/blood
- Blood Glucose/drug effects
- Blood Glucose/metabolism
- Cholesterol, Dietary
- Cytochrome P-450 Enzyme System/metabolism
- Diabetes Mellitus, Experimental/blood
- Diabetes Mellitus, Experimental/chemically induced
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Type 1/blood
- Diabetes Mellitus, Type 1/chemically induced
- Diabetes Mellitus, Type 1/drug therapy
- Glucosides/pharmacology
- Heparin/analogs & derivatives
- Heparin/metabolism
- Hyperlipidemias/blood
- Hyperlipidemias/drug therapy
- Hyperlipidemias/genetics
- Lipoproteins/blood
- Lipoproteins/metabolism
- Liver/drug effects
- Liver/metabolism
- Male
- Mice, Inbred C57BL
- Mice, Knockout
- Monocytes/drug effects
- Monocytes/metabolism
- Phlorhizin/pharmacology
- Proteoglycans/metabolism
- Receptors, LDL/deficiency
- Receptors, LDL/genetics
- Sodium-Glucose Transporter 2 Inhibitors/pharmacology
- Streptozocin
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Affiliation(s)
| | - Andrew J Murphy
- Division of Preventive Medicine and Nutrition, Department of Medicine, Columbia University, New York, USA; Baker Heart and Diabetes Institute, Melbourne, Australia
| | - L A Huggins
- Division of Preventive Medicine and Nutrition, Department of Medicine, Columbia University, New York, USA; Dept. of Medicine, New York University, New York, USA
| | - Y Hu
- Division of Preventive Medicine and Nutrition, Department of Medicine, Columbia University, New York, USA; Dept. of Medicine, New York University, New York, USA
| | - Ira J Goldberg
- Division of Preventive Medicine and Nutrition, Department of Medicine, Columbia University, New York, USA; Dept. of Medicine, New York University, New York, USA
| | - Prabhakara R Nagareddy
- Division of Preventive Medicine and Nutrition, Department of Medicine, Columbia University, New York, USA; Dept. of Nutrition Sciences, University of Alabama at Birmingham, USA.
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5
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Feig JE. Regression of atherosclerosis: insights from animal and clinical studies. Ann Glob Health 2013; 80:13-23. [PMID: 24751561 DOI: 10.1016/j.aogh.2013.12.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 02/25/2014] [Accepted: 03/15/2014] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Based on studies that date back to the 1920s, regression and stabilization of atherosclerosis in humans has gone from just a dream to one that is achievable. Review of the literature indicates that the successful attempts at regression generally applied robust measures to improve plasma lipoprotein profiles. Examples include extensive lowering of plasma concentrations of atherogenic apolipoprotein B and enhancement of reverse cholesterol transport from atheromata to the liver. FINDINGS Possible mechanisms responsible for lesion shrinkage include decreased retention of atherogenic apolipoprotein B within the arterial wall, efflux of cholesterol and other toxic lipids from plaques, emigration of lesional foam cells out of the arterial wall, and influx of healthy phagocytes that remove necrotic debris as well as other components of the plaque. This review will highlight the role key players such as LXR, HDL and CCR7 have in mediating regression. CONCLUSION Although much progress has been made, there are many unanswered questions. There is, therefore, a clear need for preclinical and clinical testing of new agents expected to facilitate atherosclerosis regression with the hope that additional mechanistic insights will allow further progress.
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Affiliation(s)
- Jonathan E Feig
- Zena and Michael A. Wiener Cardiovascular Institute, Mount Sinai Medical Center, New York, NY.
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Haas ME, Attie AD, Biddinger SB. The regulation of ApoB metabolism by insulin. Trends Endocrinol Metab 2013; 24:391-7. [PMID: 23721961 PMCID: PMC3810413 DOI: 10.1016/j.tem.2013.04.001] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 04/10/2013] [Accepted: 04/12/2013] [Indexed: 01/07/2023]
Abstract
The leading cause of death in diabetic patients is cardiovascular disease. Apolipoprotein B (ApoB)-containing lipoprotein particles, which are secreted and cleared by the liver, are essential for the development of atherosclerosis. Insulin plays a key role in the regulation of ApoB. Insulin decreases ApoB secretion by promoting ApoB degradation in the hepatocyte. In parallel, insulin promotes clearance of circulating ApoB particles by the liver via the low-density lipoprotein receptor (LDLR), LDLR-related protein 1 (LRP1), and heparan sulfate proteoglycans (HSPGs). Consequently, the insulin-resistant state of type 2 diabetes (T2D) is associated with increased secretion and decreased clearance of ApoB. Here, we review the mechanisms by which insulin controls the secretion and uptake of ApoB in normal and diabetic livers.
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Affiliation(s)
- Mary E Haas
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
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Chen K, Williams KJ. Molecular mediators for raft-dependent endocytosis of syndecan-1, a highly conserved, multifunctional receptor. J Biol Chem 2013; 288:13988-13999. [PMID: 23525115 DOI: 10.1074/jbc.m112.444737] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Endocytosis via rafts has attracted considerable recent interest, but the molecular mediators remain incompletely characterized. Here, we focused on the syndecan-1 heparan sulfate proteoglycan, a highly conserved, multifunctional receptor that we previously showed to undergo raft-dependent endocytosis upon clustering. Alanine scanning mutagenesis of three to five consecutive cytoplasmic residues at a time revealed that a conserved juxtamembrane motif, MKKK, was the only region required for efficient endocytosis after clustering. Endocytosis of clustered syndecan-1 occurs in two phases, each requiring a kinase and a corresponding cytoskeletal partner. In the initial phase, ligands trigger rapid MKKK-dependent activation of ERK and the localization of syndecan-1 into rafts. Activation of ERK drives the dissociation of syndecan-1 from α-tubulin, a molecule that may act as an anchor for syndecan-1 at the plasma membrane in the basal state. In the second phase, Src family kinases phosphorylate tyrosyl residues within the transmembrane and cytoplasmic regions of syndecan-1, a process that also requires MKKK. Tyrosine phosphorylation of syndecan-1 triggers the robust recruitment of cortactin, which we found to be an essential mediator of efficient actin-dependent endocytosis. These findings represent the first detailed characterization of the molecular events that drive endocytosis of a raft-dependent receptor and identify a novel endocytic motif, MKKK. Moreover, the results provide new tools to study syndecan function and regulation during uptake of its biologically and medically important ligands, such as HIV-1, atherogenic postprandial remnant lipoproteins, and molecules implicated in Alzheimer disease.
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Affiliation(s)
- Keyang Chen
- Division of Endocrinology, Department of Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania 19140
| | - Kevin Jon Williams
- Division of Endocrinology, Department of Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.
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Hassing H, Mooij H, Guo S, Monia B, Chen K, Kulik W, Dallinga-Thie G, Nieuwdorp M, Stroes E, Williams K. Inhibition of hepatic sulfatase-2 in vivo: a novel strategy to correct diabetic dyslipidemia. Hepatology 2012; 55:1746-53. [PMID: 22234891 PMCID: PMC3345297 DOI: 10.1002/hep.25580] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
UNLABELLED Type 2 diabetes mellitus (T2DM) impairs hepatic clearance of atherogenic postprandial triglyceride-rich lipoproteins (TRLs). We recently reported that livers from T2DM db/db mice markedly overexpress the heparan sulfate glucosamine-6-O-endosulfatase-2 (SULF2), an enzyme that removes 6-O sulfate groups from heparan sulfate proteoglycans (HSPGs) and suppresses uptake of TRLs by cultured hepatocytes. In the present study, we evaluated whether Sulf2 inhibition in T2DM mice in vivo could correct their postprandial dyslipidemia. Selective second-generation antisense oligonucleotides (ASOs) targeting Sulf2 were identified. Db/db mice were treated for 5 weeks with Sulf2 ASO (20 or 50 mg/kg per week), nontarget (NT) ASO, or phosphate-buffered saline (PBS). Administration of Sulf2 ASO to db/db mice suppressed hepatic Sulf2 messenger RNA expression by 70%-80% (i.e., down to levels in nondiabetic db/m mice) and increased the ratio of tri- to disulfated disaccharides in hepatic HSPGs (P < 0.05). Hepatocytes isolated from db/db mice on NT ASO exhibited a significant impairment in very-low-density lipoprotein (VLDL) binding that was entirely corrected in db/db mice on Sulf2 ASO. Sulf2 ASO lowered the random, nonfasting plasma triglyceride (TG) levels by 50%, achieving nondiabetic values. Most important, Sulf2 ASO treatment flattened the plasma TG excursions in db/db mice after corn-oil gavage (iAUC, 1,500 ± 470 mg/dL·h for NT ASO versus 160 ± 40 mg/dL · h for Sulf2 ASO\P < 0.01). CONCLUSIONS Despite extensive metabolic derangements in T2DM mice, inhibition of a single dys-regulated molecule, SULF2, normalizes the VLDL-binding capacity of their hepatocytes and abolishes postprandial hypertriglyceridemia. These findings provide a key proof of concept in vivo to support Sulf2 inhibition as an attractive strategy to improve metabolic dyslipidemia.
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Affiliation(s)
- H.C. Hassing
- Department of Vascular Medicine, Academic Medical Center, Amsterdam, the Netherlands
| | - H. Mooij
- Department of Vascular Medicine, Academic Medical Center, Amsterdam, the Netherlands
| | - S. Guo
- Department of Antisense Drug Discovery, Isis Pharmaceuticals Inc, Carlsbad, CA USA
| | - B.P. Monia
- Department of Antisense Drug Discovery, Isis Pharmaceuticals Inc, Carlsbad, CA USA
| | - Keyang Chen
- Section of Endocrinology, Diabetes and Metabolism, Temple University School of Medicine, Philadelphia, PA USA
| | - W. Kulik
- Laboratory of Genetic and Metabolic Diseases, Academic Medical Center, Amsterdam, The Netherlands
| | - G.M. Dallinga-Thie
- Department of Vascular Medicine, Academic Medical Center, Amsterdam, the Netherlands,Department of Experimental Vascular Medicine, Academic Medical Center, Amsterdam, the Netherlands
| | - M. Nieuwdorp
- Department of Vascular Medicine, Academic Medical Center, Amsterdam, the Netherlands
| | - E.S.G. Stroes
- Department of Vascular Medicine, Academic Medical Center, Amsterdam, the Netherlands
| | - K.J. Williams
- Section of Endocrinology, Diabetes and Metabolism, Temple University School of Medicine, Philadelphia, PA USA
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Planer D, Metzger S, Zcharia E, Wexler ID, Vlodavsky I, Chajek-Shaul T. Role of heparanase on hepatic uptake of intestinal derived lipoprotein and fatty streak formation in mice. PLoS One 2011; 6:e18370. [PMID: 21483695 PMCID: PMC3070732 DOI: 10.1371/journal.pone.0018370] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 03/06/2011] [Indexed: 12/20/2022] Open
Abstract
Background Heparanase modulates the level of heparan sulfate proteoglycans (HSPGs) which have an important role in multiple cellular processes. Recent studies indicate that HSPGs have an important function in hepatic lipoprotein handling and processes involving removal of lipoprotein particles. Principal Findings To determine the effects of decreased HSPGs chain length on lipoprotein metabolism and atherosclerosis, transgenic mice over-expressing the human heparanase gene were studied. Hepatic lipid uptake in hpa-Tg mice were evaluated by giving transgenic mice oral fat loads and labeled retinol. Sections of aorta from mice over-expressing heparanase (hpa-Tg) and controls (C57/BL6) fed an atherogenic diet were examined for evidence of atherosclerosis. Heparanase over-expression results in reduced hepatic clearance of postprandial lipoproteins and higher levels of fasting and postprandial serum triglycerides. Heparanase over-expression also induces formation of fatty streaks in the aorta. The mean lesion cross-sectional area in heparanase over-expressing mice was almost 6 times higher when compared to control mice (23,984 µm2±5,922 vs. 4,189 µm2±1,130, p<0.001). Conclusions Over-expression of heparanase demonstrates the importance of HSPGs for the uptake of intestinal derived lipoproteins and its role in the formation of fatty streaks.
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Affiliation(s)
- David Planer
- Department of Medicine, Hadassah-Hebrew University Medical Center, Mount Scopus, Jerusalem, Israel
| | - Shulamit Metzger
- Department of Medicine, Hadassah-Hebrew University Medical Center, Mount Scopus, Jerusalem, Israel
| | - Eyal Zcharia
- Sharett Institute of Oncology, Hadassah-Hebrew University Medical Center, Ein Kerem, Jerusalem, Israel
| | - Isaiah D. Wexler
- Department of Pediatrics, Hadassah-Hebrew University Medical Center, Mount Scopus, Jerusalem, Israel
| | - Israel Vlodavsky
- Sharett Institute of Oncology, Hadassah-Hebrew University Medical Center, Ein Kerem, Jerusalem, Israel
| | - Tova Chajek-Shaul
- Department of Medicine, Hadassah-Hebrew University Medical Center, Mount Scopus, Jerusalem, Israel
- * E-mail:
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Koide CL, Collier AC, Berry MJ, Panee J. The effect of bamboo extract on hepatic biotransforming enzymes--findings from an obese-diabetic mouse model. JOURNAL OF ETHNOPHARMACOLOGY 2011; 133:37-45. [PMID: 20832461 PMCID: PMC3471658 DOI: 10.1016/j.jep.2010.08.062] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 08/26/2010] [Accepted: 08/31/2010] [Indexed: 05/23/2023]
Abstract
AIM OF THE STUDY Bamboo leaves are used as a component in traditional Chinese medicine for the anti-inflammatory function. Our previous studies have demonstrated that an ethanol/water extract from Phyllostachys edulis ameliorated obesity-associated chronic systemic inflammation in mice, and therefore relieving the symptoms of type 2 diabetes. The aim of this project was to further investigate the effects of this bamboo extract on hepatic biotransformation enzymes in both lean and obese mice, as an initial step in the toxicological evaluation of using this traditional medicine in obese/diabetic population. MATERIALS AND METHODS Male C57BL/6J mice were randomized to 4 groups and fed standard (10% kcal from fat) diet with or without bamboo extract supplementation at a dose of 10 gram per kilogram diet (n=10 and n=9, respectively), or high fat (45% kcal from fat) diet with or without bamboo extract (n=8 and N=7, respectively). The dietary treatment lasted for 6 months. Subsequently, the activities and expression of the major Phase I and II hepatic biotransformation enzymes were assessed in subcellular fractions from murine livers. RESULTS Three groups of mice, lean bamboo extract-supplemented, obese/diabetic, and bamboo extract-supplemented obese/diabetic, showed greater activities of cytochromes P450 1a2 and 3a11 compared to control but no changes in the expression level of these proteins. For Phase II enzymes, bamboo extract supplementation in lean mice caused decreased glutathione-S-transferase activity (-12%) and greater uridine diphosphate glucuronosyltransferase activity (+46%), but had no effect on sulfotransferase activity. Conversely, the obese/diabetic condition itself increased glutathione-S-transferase and uridine diphosphate glucuronosyltransferase activities, but decreased total sulfotransferase activity and sulfotransferase 2a1 expression. CONCLUSIONS Bamboo extract and obesity/diabetes show significant independent effects on hepatic biotransformation as well as interaction effects in mice. These changes may alter the clearance of endo- and xenobiotics, including bamboo extract itself, hence this effect should be carefully considered in the medicinal application of bamboo extract as it has potential to alter its own metabolism and that of other medications concurrently administered to obese diabetic patients.
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Affiliation(s)
- Cheryl L.K. Koide
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street BSB 222, Honolulu, HI 96813, United States
| | - Abby C. Collier
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street BSB 222, Honolulu, HI 96813, United States
| | - Marla J. Berry
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street BSB 222, Honolulu, HI 96813, United States
| | - Jun Panee
- Department of Cell and Molecular Biology, John A. Burns School of Medicine, University of Hawaii at Manoa, 651 Ilalo Street BSB 222, Honolulu, HI 96813, United States
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Chen K, Liu ML, Schaffer L, Li M, Boden G, Wu X, Williams KJ. Type 2 diabetes in mice induces hepatic overexpression of sulfatase 2, a novel factor that suppresses uptake of remnant lipoproteins. Hepatology 2010; 52:1957-67. [PMID: 21049473 PMCID: PMC2991429 DOI: 10.1002/hep.23916] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Accepted: 08/03/2010] [Indexed: 12/22/2022]
Abstract
UNLABELLED Type 2 diabetes mellitus (T2DM) impairs hepatic clearance of atherogenic postprandial remnant lipoproteins. Our work and that of others have identified syndecan-1 heparan sulfate proteoglycans (HSPGs) as remnant lipoprotein receptors. Nevertheless, defects in the T2DM liver have not been molecularly characterized, and neither has the correction that occurs upon caloric restriction. We used microarrays to compare expression of proteoglycan-related genes in livers from control db/m mice; obese, T2DM db/db littermates fed ad libitum (AL); and db/db mice pair-fed to match the intake of db/m mice. Surprisingly, the arrays identified only one gene whose dysregulation by T2DM would disrupt HSPG structure: the heparan sulfate glucosamine-6-O-endosulfatase-2 (Sulf2). SULF2 degrades HSPGs by removing 6-O sulfate groups, but had no previously known role in diabetes or lipoprotein biology. Follow-up quantitative polymerase chain reaction assays revealed a striking 11-fold induction of Sulf2 messenger RNA in the livers of AL T2DM mice compared with controls. Immunoblots demonstrated induction of SULF2 in AL livers, with restoration toward normal in livers from pair-fed db/db mice. Knockdown of SULF2 in cultured hepatocytes doubled HSPG-mediated catabolism of model remnant lipoproteins. Notably, co-immunoprecipitations revealed a persistent physical association of SULF2 with syndecan-1. To identify mechanisms of SULF2 dysregulation in T2DM, we found that advanced glycosylation end products provoked a 10-fold induction in SULF2 expression by cultured hepatocytes and an approximately 50% impairment in their catabolism of remnants and very low-density lipoprotein, an effect that was entirely reversed by SULF2 knockdown. Adiponectin and insulin each suppressed SULF2 protein in cultured liver cells and in murine livers in vivo, consistent with a role in energy flux. Likewise, both hormones enhanced remnant lipoprotein catabolism in vitro. CONCLUSION SULF2 is an unexpected suppressor of atherogenic lipoprotein clearance by hepatocytes and an attractive target for inhibition.
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Affiliation(s)
- Keyang Chen
- Temple University School of Medicine, Philadelphia, PA USA
| | - Ming-Lin Liu
- Temple University School of Medicine, Philadelphia, PA USA
| | - Lana Schaffer
- Consortium for Functional Glycomics, Scripps Research Institute, La Jolla, CA USA
| | - Mingzhen Li
- Temple University School of Medicine, Philadelphia, PA USA
| | - Guenther Boden
- Temple University School of Medicine, Philadelphia, PA USA
| | - Xiangdong Wu
- Temple University School of Medicine, Philadelphia, PA USA
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12
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Kuwabara A, Satoh M, Tomita N, Sasaki T, Kashihara N. Deterioration of glomerular endothelial surface layer induced by oxidative stress is implicated in altered permeability of macromolecules in Zucker fatty rats. Diabetologia 2010; 53:2056-65. [PMID: 20526760 PMCID: PMC2910881 DOI: 10.1007/s00125-010-1810-0] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2010] [Accepted: 05/06/2010] [Indexed: 02/07/2023]
Abstract
AIMS/HYPOTHESIS The glomerular endothelial layer is coated by the endothelial surface layer (ESL), which is suggested to play a role in regulation of the permselectivity of macromolecules. Production of heparanase, a degrading enzyme of the ESL, is induced by reactive oxygen species (ROS). We hypothesised that oxidative stress could cause deterioration of the glomerular ESL by induction of heparanase, resulting in increased glomerular permeability. METHODS Male Zucker fatty (ZF) rats with albuminuria and Zucker lean (ZL) rats were used in this study. Some of the ZF rats were treated with the angiotensin II receptor blocker, irbesartan. We determined the amount of ESL by wheat germ agglutinin staining and heparan sulphate proteoglycan production by western blot analysis. Glomerular hyperfiltration of macromolecules was visualised using in vivo microscopy. We used 2',7'-dichlorofluorescein diacetate-derived chemiluminescence staining to assess ROS production, and heparanase production and expression were determined by western blot analysis and quantitative real-time polymerase chain reaction respectively. RESULTS By 18 weeks of age, ZF rats had developed albuminuria. The glomerular endothelial cell glycocalyx was significantly decreased in ZF compared with ZL rats. Glomerular filtration and the permeability of macromolecules were increased in ZF, but not in ZL rats. Glomerular ROS and heparanase production were significantly increased in ZF compared with ZL rats. These changes in ZF rats were reversed by irbesartan treatment. CONCLUSIONS/INTERPRETATION Increased oxidative stress induces glomerular ESL deterioration in part through increased heparanase levels, resulting in exacerbation of glomerular permselectivity and development of albuminuria.
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Affiliation(s)
- A. Kuwabara
- Division of Nephrology and Hypertension, Department of Internal Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192 Japan
| | - M. Satoh
- Division of Nephrology and Hypertension, Department of Internal Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192 Japan
| | - N. Tomita
- Division of Nephrology and Hypertension, Department of Internal Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192 Japan
| | - T. Sasaki
- Division of Nephrology and Hypertension, Department of Internal Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192 Japan
| | - N. Kashihara
- Division of Nephrology and Hypertension, Department of Internal Medicine, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192 Japan
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13
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Abstract
PURPOSE OF REVIEW Remnant lipoproteins that persist in the bloodstream after each meal have become increasingly important contributors to atherosclerotic vascular disease, owing to the spread of overnutrition, underexertion, obesity, insulin resistance, and type 2 diabetes. Here, we review recent work that clarified long-standing controversies over the molecular mediators of remnant clearance by the liver, as well as their dysregulation - but possible correction - during alterations in caloric balance. RECENT FINDINGS Two endocytic receptors, the syndecan-1 heparan sulfate proteoglycan (HSPG) and the LDL receptor, plus one docking receptor, SR-BI, significantly contribute to normal hepatic remnant catabolism. Compelling evidence exists for dysfunction of the syndecan-1 HSPG in diabetic states. The major molecular defect identified so far in poorly controlled type 1 diabetes is impaired hepatic HSPG assembly. In contrast, the primary defect in hepatic HSPGs in type 2 diabetes appears to arise from accelerated de-sulfation, owing to the induction of a sulfatase. Moreover, short-term caloric restriction restores hepatic expression of this sulfatase towards normal. SUMMARY Correct identification of hepatic remnant receptors has finally allowed investigations of their molecular dysregulation in diabetes and related conditions. New work points to novel therapeutic targets to correct postprandial dyslipoproteinemia and its consequent arterial damage.
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Affiliation(s)
- Kevin Jon Williams
- Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
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14
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Yamauchi Y, Deguchi N, Takagi C, Tanaka M, Dhanasekaran P, Nakano M, Handa T, Phillips MC, Lund-Katz S, Saito H. Role of the N- and C-terminal domains in binding of apolipoprotein E isoforms to heparan sulfate and dermatan sulfate: a surface plasmon resonance study. Biochemistry 2010; 47:6702-10. [PMID: 18507396 DOI: 10.1021/bi8003999] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ability of apolipoprotein E (apoE) to bind to cell-surface glycosaminoglycans (GAGs) is important for lipoprotein remnant catabolism. Using surface plasmon resonance, we previously showed that the binding of apoE to heparin is a two-step process; the initial binding involves fast electrostatic interaction, followed by a slower hydrophobic interaction. Here we examined the contributions of the N- and C-terminal domains to each step of the binding of apoE isoforms to heparan sulfate (HS) and dermatan sulfate (DS). ApoE3 bound to less sulfated HS and DS with a decreased favorable free energy of binding in the first step compared to heparin, indicating that the degree of sulfation has a major effect on the electrostatic interaction of GAGs with apoE. Mutation of a key Lys residue in the N-terminal heparin binding site of apoE significantly affected this electrostatic interaction. Progressive truncation of the C-terminal alpha-helical regions which favors the monomeric form of apoE3 greatly weakened the ability of apoE3 to bind to HS, with a much reduced favorable free energy of binding of the first step, suggesting that the C-terminal domain contributes to the GAG binding of apoE by the oligomerization effect. In agreement with this, dimerization of the apoE3 N-terminal fragment via disulfide linkage restored the electrostatic interaction of apoE with HS. Significantly, apoE4 exhibited much stronger binding to HS and DS than apoE2 or apoE3 in both lipid-free and lipidated states, perhaps resulting from enhanced electrostatic interaction through the N-terminal domain. This isoform difference in GAG binding of apoE may be physiologically significant such as in the retention of apoE-containing lipoproteins in the arterial wall.
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Affiliation(s)
- Yuko Yamauchi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
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15
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Bishop JR, Foley E, Lawrence R, Esko JD. Insulin-dependent diabetes mellitus in mice does not alter liver heparan sulfate. J Biol Chem 2010; 285:14658-62. [PMID: 20236939 DOI: 10.1074/jbc.m110.112391] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Diabetes -associated hyperlipidemia is generally attributed to reduced clearance of plasma lipoproteins, especially remnant lipoproteins enriched in cholesterol and triglycerides. Hepatic clearance of remnants occurs via low density lipoprotein receptors and the heparan sulfate proteoglycan, syndecan-1. Previous studies have suggested alterations in heparan sulfate proteoglycan metabolism in rat and mouse diabetic models, consistent with the idea that diabetic dyslipidemia might be caused by alterations in proteoglycan expression in the liver. In this study we analyzed the content and composition of liver heparan sulfate in streptozotocin-induced insulin-deficient diabetic mice that displayed fasting hypertriglyceridemia and delayed clearance of dietary triglyceride-rich lipoproteins. No differences between normal and diabetic littermates in liver heparan sulfate content, sulfation, syndecan-1 protein levels, or affinity for heparin-binding ligands, such as apolipoprotein E or fibroblast growth factor-2, were noted. Decreased incorporation of [(35)S]sulfate in insulin-deficient mice in vivo was observed, but the decrease was due to increased plasma inorganic sulfate, which reduced the efficiency of labeling of liver heparan sulfate. These results show that hyperlipidemia in insulin-deficient mice is not due to changes in hepatic heparan sulfate composition.
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Affiliation(s)
- Joseph R Bishop
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, California 92093, USA
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16
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Adhikari N, Basi DL, Townsend D, Rusch M, Mariash A, Mullegama S, Watson A, Larson J, Tan S, Lerman B, Esko JD, Selleck SB, Hall JL. Heparan sulfate Ndst1 regulates vascular smooth muscle cell proliferation, vessel size and vascular remodeling. J Mol Cell Cardiol 2010; 49:287-93. [PMID: 20206635 DOI: 10.1016/j.yjmcc.2010.02.022] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Revised: 02/19/2010] [Accepted: 02/22/2010] [Indexed: 11/18/2022]
Abstract
Heparan sulfate proteoglycans are abundant molecules in the extracellular matrix and at the cell surface. Heparan sulfate chains are composed of groups of disaccharides whose side chains are modified through a series of enzymatic reactions. Deletion of these enzymes alters heparan sulfate fine structure and leads to changes in cell proliferation and tissue development. The role of heparan sulfate modification has not been explored in the vessel wall. The goal of this study was to test the hypothesis that altering heparan sulfate fine structure would impact vascular smooth muscle cell (VSMC) proliferation, vessel structure, and remodeling in response to injury. A heparan sulfate modifying enzyme, N-deacetylase N-sulfotransferase1 (Ndst1) was deleted in smooth muscle resulting in decreased N- and 2-O sulfation of the heparan sulfate chains. Smooth muscle specific deletion of Ndst1 led to a decrease in proliferating VSMCs and the circumference of the femoral artery in neonatal and adult mice. In response to vascular injury, mice lacking Ndst1 exhibited a significant reduction in lesion formation. Taken together, these data provide new evidence that modification of heparan sulfate fine structure through deletion of Ndst1 is sufficient to decrease VSMC proliferation and alter vascular remodeling.
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17
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Abstract
The recent discovery of a dysfunctional mutation of GPIHBP1 in a man with chylomicronemia implicates this protein in human physiology. GPIHBP1 can be placed in the larger context of other molecular participants in chylomicron docking and hydrolysis on microvascular endothelium, caloric delivery, and remnant lipoprotein generation. Critical questions include the regulation—and dysregulation—of these processes in states of overnutrition, underexertion, obesity, insulin resistance, and diabetes.
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Affiliation(s)
- Kevin Jon Williams
- From the Section of Endocrinology, Diabetes, and Metabolism, Temple University School of Medicine, Philadelphia, Pa
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18
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Williams KJ. Molecular processes that handle -- and mishandle -- dietary lipids. J Clin Invest 2008; 118:3247-59. [PMID: 18830418 DOI: 10.1172/jci35206] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Overconsumption of lipid-rich diets, in conjunction with physical inactivity, disables and kills staggering numbers of people worldwide. Recent advances in our molecular understanding of cholesterol and triglyceride transport from the small intestine to the rest of the body provide a detailed picture of the fed/fasted and active/sedentary states. Key surprises include the unexpected nature of many pivotal molecular mediators, as well as their dysregulation - but possible reversibility - in obesity, diabetes, inactivity, and related conditions. These mechanistic insights provide new opportunities to correct dyslipoproteinemia, accelerated atherosclerosis, insulin resistance, and other deadly sequelae of overnutrition and underexertion.
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Affiliation(s)
- Kevin Jon Williams
- Division of Endocrinology, Diabetes, and Metabolic Diseases, Department of Medicine, Jefferson Medical College, Thomas Jefferson University, Philadelphia, Pennsylvania 19107-5005, USA.
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19
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Matikainen N, Taskinen MR. Postprandial triglyceride-rich lipoproteins in insulin resistance and Type 2 diabetes. ACTA ACUST UNITED AC 2008. [DOI: 10.2217/17460875.3.5.531] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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20
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Goldberg IJ, Hu Y, Noh HL, Wei J, Huggins LA, Rackmill MG, Hamai H, Reid BN, Blaner WS, Huang LS. Decreased lipoprotein clearance is responsible for increased cholesterol in LDL receptor knockout mice with streptozotocin-induced diabetes. Diabetes 2008; 57:1674-82. [PMID: 18346984 DOI: 10.2337/db08-0083] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Patients with diabetes often have dyslipidemia and increased postprandial lipidmia. Induction of diabetes in LDL receptor (Ldlr(-/-)) knockout mice also leads to marked dyslipidemia. The reasons for this are unclear. RESEARCH DESIGN AND METHODS We placed Ldlr(-/-) and heterozygous LDL receptor knockout (Ldlr(+/-)) mice on a high-cholesterol (0.15%) diet, induced diabetes with streptozotocin (STZ), and assessed reasons for differences in plasma cholesterol. RESULTS STZ-induced diabetic Ldlr(-/-) mice had plasma cholesterol levels more than double those of nondiabetic controls. Fast-performance liquid chromatography and ultracentrifugation showed an increase in both VLDL and LDL. Plasma VLDL became more cholesterol enriched, and both VLDL and LDL had a greater content of apolipoprotein (apo)E. In LDL the ratio of apoB48 to apoB100 was increased. ApoB production, assessed using [(35)S]methionine labeling in Triton WR1339-treated mice, was not increased in fasting STZ-induced diabetic mice. Similarly, postprandial lipoprotein production was not increased. Reduction of cholesterol in the diet to normalize the amount of cholesterol intake by the control and STZ-induced diabetic animals reduced plasma cholesterol levels in STZ-induced diabetic mice, but plasma cholesterol was still markedly elevated compared with nondiabetic controls. LDL from STZ-induced diabetic mice was cleared from the plasma and trapped more rapidly by livers of control mice. STZ treatment reduced liver expression of the proteoglycan sulfation enzyme, heparan sulfate N-deacetylase/N-sulfotrasferase-1, an effect that was reproduced in cultured hepatocytyes by a high glucose-containing medium. CONCLUSIONS STZ-induced diabetic, cholesterol-fed mice developed hyperlipidemia due to a non-LDL receptor defect in clearance of circulating apoB-containing lipoproteins.
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Affiliation(s)
- Ira J Goldberg
- Division of Preventive Medicine, Columbia University, New York, New York 10032, USA.
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21
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Williams KJ, Feig JE, Fisher EA. Rapid regression of atherosclerosis: insights from the clinical and experimental literature. ACTA ACUST UNITED AC 2008; 5:91-102. [PMID: 18223541 DOI: 10.1038/ncpcardio1086] [Citation(s) in RCA: 149] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Accepted: 10/17/2007] [Indexed: 01/09/2023]
Abstract
Looking back at animal and clinical studies published since the 1920s, the notion of rapid regression and stabilization of atherosclerosis in humans has evolved from a fanciful goal to one that might be achievable pharmacologically, even for advanced plaques. Our review of this literature indicates that successful regression of atherosclerosis generally requires robust measures to improve plasma lipoprotein profiles. Examples of such measures include extensive lowering of plasma concentrations of atherogenic apolipoprotein B (apoB)-lipoproteins and enhancement of 'reverse' lipid transport from atheromata into the liver, either alone or in combination. Possible mechanisms responsible for lesion shrinkage include decreased retention of apoB-lipoproteins within the arterial wall, efflux of cholesterol and other toxic lipids from plaques, emigration of foam cells out of the arterial wall, and influx of healthy phagocytes that remove necrotic debris and other components of the plaque. Unfortunately, the clinical agents currently available cause less dramatic changes in plasma lipoprotein levels, and, thereby, fail to stop most cardiovascular events. Hence, there is a clear need for testing of new agents expected to facilitate atherosclerosis regression. Additional mechanistic insights will allow further progress.
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Affiliation(s)
- Kevin Jon Williams
- Department of Medicine/Division of Endocrinology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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22
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Tabas I, Williams KJ, Borén J. Subendothelial lipoprotein retention as the initiating process in atherosclerosis: update and therapeutic implications. Circulation 2007; 116:1832-44. [PMID: 17938300 DOI: 10.1161/circulationaha.106.676890] [Citation(s) in RCA: 944] [Impact Index Per Article: 55.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The key initiating process in atherogenesis is the subendothelial retention of apolipoprotein B-containing lipoproteins. Local biological responses to these retained lipoproteins, including a chronic and maladaptive macrophage- and T-cell-dominated inflammatory response, promote subsequent lesion development. The most effective therapy against atherothrombotic cardiovascular disease to date--low density lipoprotein-lowering drugs--is based on the principle that decreasing circulating apolipoprotein B lipoproteins decreases the probability that they will enter and be retained in the subendothelium. Ongoing improvements in this area include more aggressive lowering of low-density lipoprotein and other atherogenic lipoproteins in the plasma and initiation of low-density lipoprotein-lowering therapy at an earlier age in at-risk individuals. Potential future therapeutic approaches include attempts to block the interaction of apolipoprotein B lipoproteins with the specific subendothelial matrix molecules that mediate retention and to interfere with accessory molecules within the arterial wall that promote retention such as lipoprotein lipase, secretory sphingomyelinase, and secretory phospholipase A2. Although not the primary focus of this review, therapeutic strategies that target the proatherogenic responses to retained lipoproteins and that promote the removal of atherogenic components of retained lipoproteins also hold promise. The finding that certain human populations of individuals who maintain lifelong low plasma levels of apolipoprotein B lipoproteins have an approximately 90% decreased risk of coronary artery disease gives hope that our further understanding of the pathogenesis of this leading killer could lead to its eradication.
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Affiliation(s)
- Ira Tabas
- Department of Medicine, Columbia University Medical Center, 630 W 168th St, New York, NY 10032, USA.
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23
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MacArthur JM, Bishop JR, Stanford KI, Wang L, Bensadoun A, Witztum JL, Esko JD. Liver heparan sulfate proteoglycans mediate clearance of triglyceride-rich lipoproteins independently of LDL receptor family members. J Clin Invest 2007; 117:153-64. [PMID: 17200715 PMCID: PMC1716206 DOI: 10.1172/jci29154] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Accepted: 10/03/2006] [Indexed: 12/17/2022] Open
Abstract
We examined the role of hepatic heparan sulfate in triglyceride-rich lipoprotein metabolism by inactivating the biosynthetic gene GlcNAc N-deacetylase/N-sulfotransferase 1 (Ndst1) in hepatocytes using the Cre-loxP system, which resulted in an approximately 50% reduction in sulfation of liver heparan sulfate. Mice were viable and healthy, but they accumulated triglyceride-rich lipoprotein particles containing apoB-100, apoB-48, apoE, and apoCI-IV. Compounding the mutation with LDL receptor deficiency caused enhanced accumulation of both cholesterol- and triglyceride-rich particles compared with mice lacking only LDL receptors, suggesting that heparan sulfate participates in the clearance of cholesterol-rich lipoproteins as well. Mutant mice synthesized VLDL normally but showed reduced plasma clearance of human VLDL and a corresponding reduction in hepatic VLDL uptake. Retinyl ester excursion studies revealed that clearance of intestinally derived lipoproteins also depended on hepatocyte heparan sulfate. These findings show that under normal physiological conditions, hepatic heparan sulfate proteoglycans play a crucial role in the clearance of both intestinally derived and hepatic lipoprotein particles.
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Affiliation(s)
- Jennifer M. MacArthur
- Biomedical Sciences Graduate Program and
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Joseph R. Bishop
- Biomedical Sciences Graduate Program and
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Kristin I. Stanford
- Biomedical Sciences Graduate Program and
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Lianchun Wang
- Biomedical Sciences Graduate Program and
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - André Bensadoun
- Biomedical Sciences Graduate Program and
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Joseph L. Witztum
- Biomedical Sciences Graduate Program and
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | - Jeffrey D. Esko
- Biomedical Sciences Graduate Program and
Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California, USA.
Division of Nutritional Sciences, Cornell University, Ithaca, New York, USA.
Department of Medicine, University of California, San Diego, La Jolla, California, USA
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24
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van den Born J, Pisa B, Bakker MAH, Celie JWAM, Straatman C, Thomas S, Viberti GC, Kjellen L, Berden JHM. No change in glomerular heparan sulfate structure in early human and experimental diabetic nephropathy. J Biol Chem 2006; 281:29606-13. [PMID: 16885165 DOI: 10.1074/jbc.m601552200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Heparan sulfate (HS) proteoglycans are major anionic glycoconjugates of the glomerular basement membrane and are thought to contribute to the permeability properties of the glomerular capillary wall. In this study we evaluated whether the development of (micro) albuminuria in early human and experimental diabetic nephropathy is related to changes in glomerular HS expression or structure. Using a panel of recently characterized antibodies, glomerular HS expression was studied in kidney biopsies of type I diabetic patients with microalbuminuria or early albuminuria and in rat renal tissue after 5 months diabetes duration. Glomerular staining, however, revealed no differences between control and diabetic specimens. A significant (p < 0.05) approximately 60% increase was found in HS N-deacetylase activity, a key enzyme in HS sulfation reactions, in diabetic glomeruli. Structural analysis of glomerular HS after in vivo and in vitro radiolabeling techniques revealed no changes in HS N-sulfation or charge density. Also HS chain length, protein binding properties, as well as disaccharide composition did not differ between control and diabetic glomerular HS samples. These results indicate that in experimental and early human diabetic nephropathy, increased urinary albumin excretion is not caused by loss of glomerular HS expression or sulfation and suggest other mechanisms to be responsible for increased glomerular albumin permeability.
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Affiliation(s)
- Jacob van den Born
- Department of Nephrology, Radboud University Medical Center Nijmegen, P. O. Box 9101, 6500 HB Nijmegen, The Netherlands.
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