Chronic leucine exposure results in reduced but reversible glucose-stimulated insulin secretion in INS-1 cells

Zhang,Xiujuan; Han,Wenxia; Jiang,Xiuyun; Li,Min; Gao,Ling; Zhao,Jia Jun

doi:10.3892/mmr.2014.2122

Chronic leucine exposure results in reduced but reversible glucose-stimulated insulin secretion in INS-1 cells

Authors:
- Xiujuan Zhang
- Wenxia Han
- Xiuyun Jiang
- Min Li
- Ling Gao
- Jia Jun Zhao
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Affiliations: Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong 250021, P.R. China, The Scientific Center, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong 250021, P.R. China
Published online on: April 8, 2014 https://doi.org/10.3892/mmr.2014.2122
Pages: 2554-2558

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Abstract

Previous studies have demonstrated that sustained high leucine exposure decreases glucose‑stimulated insulin secretion (GSIS). However, whether this effect is recoverable following the removal of leucine is unclear. Pancreatic/duodenal homeobox‑1 (PDX‑1) and its downstream target, glucose transporter 2 (GLUT2), are reported to be positively associated with insulin secretion. However, it also remains unclear whether the effect of leucine on GSIS is accompanied by alterations in PDX‑1 and GLUT2. In the present study, insulin secretion, insulin content, PDX‑1 and GLUT2 protein expression in INS‑1 (rat insulinoma cell line) cells were assessed following a 24‑h incubation in 40 mmol/l leucine. Half of the cells were incubated in leucine‑free media for a further 24 h to observe the abovementioned effects. In contrast to the control, 40 mmol/l leucine for 24 or 48 h diminished GSIS at high glucose concentrations by 11% (P=0.026) or 22% (P=0.003), insulin content by 14% (P=0.008) or 20% (P=0.002), as well as decreasing PDX‑1 and GLUT2 expression. When leucine was removed from the media for a further 24‑h incubation, in comparison with those cells that were maintained in leucine treatment for 24 and 48 h, the high GSIS increased by 13% (P=0.032) and 27% (P=0.002), insulin content was augmented by 10% (P=0.014) and 20% (P=0.003), and the protein expression of PDX‑1 and GLUT2 also increased. The present study demonstrates that sustained high concentrations of leucine induce a reversible impairment of GSIS and alter insulin content, which is mediated by PDX‑1 and GLUT2, in INS‑1 cells.

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1	DeFronzo RA, Bonadonna RC and Ferrannini E: Pathogenesis of NIDDM. A balanced overview. Diabetes Care. 15:318–368. 1992. View Article : Google Scholar : PubMed/NCBI
2	Porte D Jr and Kahn SE: beta-cell dysfunction and failure in type 2 diabetes: potential mechanisms. Diabetes. 50(Suppl 1): S160–S163. 2001. View Article : Google Scholar : PubMed/NCBI
3	Sun Y, Zhang L, Gu HF, et al: Peroxisome proliferator-activated receptor-alpha regulates the expression of pancreatic/duodenal homeobox-1 in rat insulinoma (INS-1) cells and ameliorates glucose-induced insulin secretion impaired by palmitate. Endocrinology. 149:662–671. 2008. View Article : Google Scholar
4	Van de Casteele M, Kefas BA, Cai Y, et al: Prolonged culture in low glucose induces apoptosis of rat pancreatic beta-cells through induction of c-myc. Biochem Biophys Res Commun. 312:937–944. 2003.PubMed/NCBI
5	Unger RH and Zhou YT: Lipotoxicity of beta-cells in obesity and in other causes of fatty acid spillover. Diabetes. 50(Suppl 1): S118–S121. 2001. View Article : Google Scholar : PubMed/NCBI
6	Ling Z and Pipeleers DG: Prolonged exposure of human beta cells to elevated glucose levels results in sustained cellular activation leading to a loss of glucose regulation. J Clin Invest. 98:2805–2812. 1996. View Article : Google Scholar : PubMed/NCBI
7	Briaud I, Harmon JS, Kelpe CL, Segu VB and Poitout V: Lipotoxicity of the pancreatic beta-cell is associated with glucose-dependent esterification of fatty acids into neutral lipids. Diabetes. 50:315–321. 2001. View Article : Google Scholar : PubMed/NCBI
8	Robertson RP, Harmon J, Tran PO and Poitout V: Beta-cell glucose toxicity, lipotoxicity, and chronic oxidative stress in type 2 diabetes. Diabetes. 53(Suppl 1): S119–S124. 2004. View Article : Google Scholar : PubMed/NCBI
9	Anello M, Ucciardello V, Piro S, et al: Chronic exposure to high leucine impairs glucose-induced insulin release by lowering the ATP-to-ADP ratio. Am J Physiol Endocrinol Metab. 281:E1082–E1087. 2001.PubMed/NCBI
10	Yang J, Wong RK, Park M, et al: Leucine regulation of glucokinase and ATP synthase sensitizes glucose-induced insulin secretion in pancreatic beta-cells. Diabetes. 55:193–201. 2006. View Article : Google Scholar : PubMed/NCBI
11	Yang J, Wong RK, Wang X, et al: Leucine culture reveals that ATP synthase functions as a fuel sensor in pancreatic beta-cells. J Biol Chem. 279:53915–53923. 2004. View Article : Google Scholar : PubMed/NCBI
12	Kaneto H, Miyatsuka T, Fujitani Y, et al: Role of PDX-1 and MafA as a potential therapeutic target for diabetes. Diabetes Res Clin Pract. 77(Suppl 1): S127–S137. 2007. View Article : Google Scholar : PubMed/NCBI
13	Fernandes A, King LC, Guz Y, Stein R, Wright CV and Teitelman G: Differentiation of new insulin-producing cells is induced by injury in adult pancreatic islets. Endocrinology. 138:1750–1762. 1997.PubMed/NCBI
14	Offield MF, Jetton TL, Labosky PA, et al: PDX-1 is required for pancreatic outgrowth and differentiation of the rostral duodenum. Development. 122:983–995. 1996.PubMed/NCBI
15	Waeber G, Thompson N, Nicod P and Bonny C: Transcriptional activation of the GLUT2 gene by the IPF-1/STF-1/IDX-1 homeobox factor. Mol Endocrinol. 10:1327–1334. 1996.PubMed/NCBI
16	Marshak S, Totary H, Cerasi E and Melloul D: Purification of the beta-cell glucose-sensitive factor that transactivates the insulin gene differentially in normal and transformed islet cells. Proc Natl Acad Sci USA. 93:15057–15062. 1996. View Article : Google Scholar : PubMed/NCBI
17	Iype T, Francis J, Garmey JC, et al: Mechanism of insulin gene regulation by the pancreatic transcription factor Pdx-1: application of pre-mRNA analysis and chromatin immunoprecipitation to assess formation of functional transcriptional complexes. J Biol Chem. 280:16798–16807. 2005. View Article : Google Scholar
18	Melloul D, Marshak S and Cerasi E: Regulation of insulin gene transcription. Diabetologia. 45:309–326. 2002. View Article : Google Scholar
19	Jonsson J, Carlsson L, Edlund T and Edlund H: Insulin-promoter-factor 1 is required for pancreas development in mice. Nature. 371:606–609. 1994. View Article : Google Scholar : PubMed/NCBI
20	Kushner JA, Ye J, Schubert M, et al: Pdx1 restores beta cell function in Irs2 knockout mice. J Clin Invest. 109:1193–1201. 2002. View Article : Google Scholar : PubMed/NCBI
21	Gremlich S, Bonny C, Waeber G and Thorens B: Fatty acids decrease IDX-1 expression in rat pancreatic islets and reduce GLUT2, glucokinase, insulin, and somatostatin levels. J Biol Chem. 272:30261–30269. 1997. View Article : Google Scholar : PubMed/NCBI
22	Leahy JL, Cooper HE, Deal DA and Weir GC: Chronic hyperglycemia is associated with impaired glucose influence on insulin secretion. A study in normal rats using chronic in vivo glucose infusions. J Clin Invest. 77:908–915. 1986. View Article : Google Scholar : PubMed/NCBI
23	Xiao CQ, Deng HM and Huang Y: Effects of supraphysiologic concentration glucose on pancreatic duodenal homeobox-1 expression and insulin secretion in rats. Chin Med J (Engl). 120:1020–1023. 2007.PubMed/NCBI
24	Lennernäs H, Nilsson D, Aquilonius SM, Ahrenstedt O, Knutson L and Paalzow LK: The effect of L-leucine on the absorption of levodopa, studied by regional jejunal perfusion in man. Br J Clin Pharmacol. 35:243–250. 1993.PubMed/NCBI
25	Ganapathy V and Radhakrishnan AN: Interaction of amino acids with glycl-L-leucine hydrolysis and transport in monkey small intestine. Clin Sci (Lond). 57:521–527. 1979.PubMed/NCBI
26	Rideau N and Simon J: L-leucine or its keto acid potentiate but do not initiate insulin release in chicken. Am J Physiol. 257:E15–E19. 1989.PubMed/NCBI
27	Zhang X, Sun N, Wang L, et al: AMP-activated protein kinase and pancreatic/duodenal homeobox-1 involved in insulin secretion under high leucine exposure in rat insulinoma beta-cells. J Cell Mol Med. 13:758–770. 2009. View Article : Google Scholar : PubMed/NCBI