Expression of the Protein Tyrosine Phosphatase-like Protein IA-2 During Pancreatic Islet Development

Roberts, Caroline; Roberts, Graham; Löbner, Kristian; Bearzatto, Massimo; Clark, Anne; Bonifacio, Ezio; Christie, Michael R.

doi:10.1177/002215540104900610

Cited by 18 publications

(18 citation statements)

References 28 publications

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“…Triple labelling of formalin-fixed mouse pancreas sections [8] was performed with rabbit antibodies to KISS1 or GPR54 (Phoenix Pharmaceuticals, Karlsruhe, Germany; 1:50 dilutions) together with guinea-pig anti-insulin (ICN Biomedical, Costa Mesa, CA, USA; 1:50) and mouse monoclonal anti-glucagon (Sigma, Dorset, UK; 1:50) antibodies. KISS1 and GPR54 immunoreactivities were visualised using Envision alkaline phosphatase-labelled polymer with Fast Red substrate (DAKO, Cambridge, UK), whereas insulin and glucagon were detected by immunofluorescence with Texas Red-conjugated anti-guinea-pig IgG and FITCconjugated anti-mouse IgG, respectively (both from Stratech, Luton, UK; 1:20 dilution).…”

Section: Immunohistochemistrymentioning

confidence: 99%

A role for kisspeptin in islet function

et al. 2006

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Aims/hypothesis We investigated the production of kisspeptin (KISS1) and the KISS1 receptor, GPR54, in pancreatic islets and determined the effects of exogenous kisspeptin on insulin secretion. Methods RT-PCR and immunohistochemistry were used to detect expression of KISS1 and GPR54 mRNAs and the production of KISS1 and GPR54 in human and mouse islets and in beta (MIN6) and alpha-(alphaTC1) cell lines. The effects of KISS1 on basal and glucose-induced insulin secretion from mouse and human islets were measured in a perifusion system. Results KISS1 and GPR54 mRNAs were both detected in human and mouse islets, and GPR54 mRNA expression was also found in the MIN6 and alphaTC1 endocrine cell lines. In sections of mouse pancreas, KISS1 and GPR54 immunoreactivities were co-localised in both beta and alpha cells within islets, but were not detected in the exocrine pancreas. Exposure of mouse and human islets to KISS1 caused a stimulation of glucose-induced (20 mmol/l) insulin secretion, but had no effect on the basal rate of secretion at a sub-stimulatory concentration of glucose (2 mmol/l). In contrast, KISS1 inhibited insulin secretion from MIN6 cells at both 2 and 20 mmol/l glucose. KISS1 had no significant effect on glucagon secretion from mouse islets. Conclusions/interpretation This is the first report to show that the GPR54/KISS1 system is expressed in the endocrine pancreas, where it influences beta cell secretory function. These observations suggest an important role for this system in the normal regulation of islet function.

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Section: Immunohistochemistrymentioning

confidence: 99%

A role for kisspeptin in islet function

et al. 2006

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“…Mouse monoclonal antibodies 76F and 3C12 against the cytoplasmic domain of IA-2 were generated as previously described (14). Rabbit antibody to the ␣ subunit of the insulin receptor (type A and B) was from Biogenesis (Poole, U.K.).…”

Section: Methodsmentioning

confidence: 99%

“…IA-2 and phogrin protein levels. Isolated islets were washed in HEPESbuffered saline and prepared for Western blotting with monoclonal antibodies to IA-2 as previously described (14). The integrated optical density of bands representing IA-2 was measured by densitometry and compared with a standard curve of purified recombinant IA-2 (23) run on each blot.…”

Section: Methodsmentioning

confidence: 99%

“…Isolated adult rat islets (200 per condition) were incubated for 2 h at 37°C in 100 l HEPESbuffered Hanks' balanced salt solution (HBSS) containing 1 mg/ml BSA, 6 mmol/l glucose, 10% methionine, cysteine-deficient amino acid mix (Amersham-Pharmacia Biotech, Amersham, U.K.), and 4 MBq EasyTag Express protein labeling mix (NEN, Hounslow, U.K.) in the presence or absence of 10 nmol/l insulin. Islets were lysed (14) and immunoprecipitated with monoclonal IA-2 antibody 76F or an irrelevant control antibody. Immune complexes were isolated on protein A Sepharose and analyzed by SDS-PAGE and autoradiography.…”

Section: Methodsmentioning

confidence: 99%

“…In contrast, IA-2 is only transiently expressed in a population of immature endocrine cells early in rat fetal islet development, but a progressive increase in IA-2 expression occurs during the first 2 weeks after birth (14). Factors that regulate IA-2 gene transcription may include glucose and other agents that increase intracellular cAMP (15); regulation of phogrin expression is rarely studied.…”

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confidence: 99%

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Different Regulated Expression of the Tyrosine Phosphatase-Like Proteins IA-2 and Phogrin by Glucose and Insulin in Pancreatic Islets

Löbner

Steinbrenner²,

Roberts³

et al. 2002

Diabetes

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1IA-2 and phogrin are tyrosine phosphatase-like proteins that may mediate interactions between secretory granules and cytoskeleton in islets and neuroendocrine tissues. We investigated factors that regulate IA-2 and phogrin expression and their relationship to maturation of insulin secretory responses that occur after birth. Islet content of IA-2, but not phogrin, increased during the first 10 days of life in rats, when insulin secretion in response to glucose increased to adult levels. In cultured 5-day-old rat islets, IA-2 protein and mRNA was increased by glucose and agents that potentiate insulin secretion by the cAMP pathway. Addition of insulin increased IA-2 protein levels and insulin biosynthesis without affecting IA-2 mRNA. Blocking insulin secretion with diazoxide or insulin action with insulin receptor antibodies inhibited glucose-induced increases in IA-2 protein, but not those of mRNA. Phogrin expression was unchanged by all agents. Thus, IA-2 is regulated at the mRNA level by glucose and elevated cAMP, whereas locally secreted insulin modulates IA-2 protein levels by stimulating biosynthesis. In contrast, phogrin expression is insensitive to factors that modify ␤-cell function. These results demonstrate differential regulation of two closely related secretory granule components and identify IA-2 as a granule membrane protein subject to autocrine regulation by insulin. Diabetes 51:2982-2988, 2002

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