(c) A plasmid containing pcDNA (empty vector), p38 MAPK or p38 MAPK-domain negative (p38 MAPK-DN) DNA was co-transfected into INS-1 cells, along with a plasmid containing the GLUT2 promoter
(c) A plasmid containing pcDNA (empty vector), p38 MAPK or p38 MAPK-domain negative (p38 MAPK-DN) DNA was co-transfected into INS-1 cells, along with a plasmid containing the GLUT2 promoter. TSH stimulated GLUT2 promoter activity, while both a dominant-negative p38MAPK isoform (p38MAPK -DN) and the specific inhibitor for p38MAPK abolished the stimulatory effect of TSH on GLUT2 promoter activity. Finally, INS-1 cells treated with TSH showed increased protein level of glucokinase and enhanced glucose-stimulated insulin secretion. Together, these results confirm that TSHR is expressed in INS-1 cells and rat pancreatic islets, and suggest that activation of the p38MAPK might be required for TSH-induced GLUT2 gene transcription in pancreatic cells. Introduction Thyroid stimulating hormone (TSH), also known as thyrotropin, belongs to a pituitary glycoprotein hormone family. Secretion of TSH from the pituitary is stimulated by thyrotropin-releasing hormone (TRH) from your hypothalamus. Once secreted, TSH primarily functions to stimulate the thyroid by binding its receptor, TSH receptor (TSHR)1. TSHR is definitely a member of the G protein-coupled receptor family and is an 82-kDa protein composed of and subunits2. Activation of TSHR prospects to the transcription, synthesis and launch of thyroid hormones via the PKA signaling pathway within the thyroid. Excepting thyroid cells, TSHR has also been reported to be indicated in many additional cells and cells, such as the mind, testes, kidney, heart, bone, adipose cells, thymus, lymphocytes and fibroblasts2,3. These varying locations of TSHR manifestation show its capacity to perform multifunctional tasks throughout the body, in addition to its best-known part in the thyroid. Recently, TSHR is definitely reported to be indicated in rabbit pancreatic islets and it suggests that TSH may directly mediate the growth of pancreatic islets by TSHR4. In medical, the glucose-stimulated insulin secretion (GSIS) is definitely elevated in the patient with Graves disease (GD, hyperthyroidism), in which the anti-TSHR antibody activates TSHR without TSH5,6. In the additional hand, higher level of TSH in Hashimotos disease (hypothyroidism) also improved serum insulin concentration7, suggesting that activation of TSHR may impact insulin secretion. Glucose transporter 2 (GLUT2), which is present within the plasma membrane ITPKB of pancreatic cells8, takes on an important part in glucose-induced insulin secretion from pancreatic cells by catalyzing the uptake of glucose into the cell9. It is a facilitative glucose transporter, and its manifestation is definitely strongly reduced in glucose-unresponsive islets in various animal models of diabetes9,10. GLUT2 contributes to the sensing of glucose not only by fueling the metabolic signaling cascade, but also by triggering a specific protein kinase A signaling pathway11. Indeed, GLUT2 cannot always be replaced by alternate GLUT isoforms, suggesting that it offers unique qualities12. Studies using cells that are manufactured with numerous GLUT isoforms to provide a similar glucose flux showed that only GLUT2 facilitates normal insulin production in response to glucose sensing13. Clinical study showed a relationship between a low level of thyroid hormones and diabetes14. In addition, serum TSH has been reported to Nardosinone be positively related to insulin concentration15. However, little is known about the direct effect of TSH and TSHR on pancreatic specific genes. In this study, we evaluated the part of TSHR in regulating the manifestation of pancreas specific-genes including GLUT2 from the activation of TSH. Results Characterization of TSHR manifestation in the rat pancreatic cells To confirm that TSHR is definitely indicated in the rat pancreas, we used an antibody against the TSHR subunit and recognized a 62-kDa band in the rat pancreas, INS-1 cells, pancreatic islets isolated from rat and the rat thyroid (positive control) (Fig.?1aCc). Using the same primers that were reported to successfully amplify the fragment of TSHR in rats16, we generated a 594-bp PCR product from your template cDNA isolated from rat pancreatic islets and INS-1 cells (Fig.?1d). Finally, immunocytochemistry and immunohistochemistry shown that TSHR is definitely indicated in both INS-1 cells (Fig.?1e) and in rat pancreatic islets (Fig.?1f). Open in a separate window Number 1 Characterization of TSHR manifestation in rat pancreatic islets and in Nardosinone INS-1 cells. (aCc) Protein isolated from rat thyroid, pancreas, pancreatic islet or INS-1 cells (shown on the top of each band) was recognized by TSHR antibody. Full-length blots are offered in Supplementary Number 1. (d) By using TSHR specific primer, PCR products were generated based on template cDNA isolated from rat pancreatic islets and two dishes of INS-1. (e) Immunocytochemistry of Nardosinone INS-1 cells with the TSHR subunit antibody (green). (f) Immunohistochemistry of TSHR and insulin (brownish) in main pancreatic islets from your rat. Pub?=?20?m. TSH increases the manifestation of GLUT2 via p38MAPK in rat pancreatic cells Having confirmed that TSHR is definitely indicated in rat pancreatic islets and in INS-1 cells, we then used INS-1 cells to analyse the effects of TSH within the manifestation of pancreas-specific gene in pancreatic cells. Firstly, we found.