| 1. |
- Aljaibeji, Hayat, et al.
(författare)
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Reduced Expression of PLCXD3 Associates With Disruption of Glucose Sensing and Insulin Signaling in Pancreatic β-Cells
- 2019
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Ingår i: Frontiers in Endocrinology. - : Frontiers Media SA. - 1664-2392. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Previous work has shown that reduced expression of PLCXD3, a member of the phosphoinositide-specific phospholipases (PI-PLC) family, impaired insulin secretion with an unclear mechanism. In the current study, we aim to investigate the mechanism underlying this effect using human islets and rat INS-1 (832/13) cells. Microarray and RNA sequencing data showed that PLCXD3 is among the highly expressed PI-PLCs in human islets and INS-1 (832/13) cells. Expression of PLCXD3 was reduced in human diabetic islets, correlated positively with Insulin and GLP1R expression and inversely with the donor's body mass index (BMI) and glycated hemoglobin (HbA1c). Expression silencing of PLCXD3 in INS-1 (832/13) cells was found to reduce glucose-stimulated insulin secretion (GSIS) and insulin content. In addition, the expression of Insulin, NEUROD1, GLUT2, GCK, INSR, IRS2, and AKT was downregulated. Cell viability and apoptosis rate were unaffected. In conclusion, our data suggest that low expression of PLCXD3 in pancreatic β-cells associates with downregulation of the key insulin signaling and insulin biosynthesis genes as well as reduction in glucose sensing.
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| 2. |
- Taneera, Jalal, et al.
(författare)
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GNAS gene is an important regulator of insulin secretory capacity in pancreatic β-cells
- 2019
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Ingår i: Gene. - : Elsevier BV. - 1879-0038 .- 0378-1119. ; 715
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Type 2 diabetes (T2D) is a complex polygenic disease with unclear mechanism. In an attempt to identify novel genes involved in β-cell function, we harness a bioinformatics method called Loss-of-function tool (LoFtool) gene score. METHODS: RNA-sequencing data from human islets were used to cross-reference genes within the 1st quartile of most intolerant LoFtool score with the 100th most expressed genes in human islets. Out of these genes, GNAS and EEF1A1 genes were selected for further investigation in diabetic islets, metabolic tissues along with their correlation with diabetic phenotypes. The influence of GNAS and EEF1A1 on insulin secretion and β-cell function were validated in INS-1 cells. RESULTS: A comparatively higher expression level of GNAS and EEF1A1 was observed in human islets than fat, liver and muscle tissues. Furthermore, diabetic islets displayed a reduced expression of GNAS, but not of EEF1A, compared to non-diabetic islets. The expression of GNAS was positively correlated with insulin secretory index, GLP1R, GIPR and inversely correlated with HbA1c. Diabetic human islets displayed a reduced cAMP generation and insulin secretory capacity in response to glucose. Moreover, siRNA silencing of GNAS in INS-1 cells reduced insulin secretion, insulin content, and cAMP production. In addition, the expression of Insulin, PDX1, and MAFA was significantly down-regulated in GNAS-silenced cells. However, cell viability and apoptosis rate were unaffected. CONCLUSION: LoFtool is a powerful tool to identify genes associated with pancreatic islets dysfunction. GNAS is a crucial gene for the β-cell insulin secretory capacity.
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| 3. |
- Taneera, Jalal, et al.
(författare)
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RORB and RORC associate with human islet dysfunction and inhibit insulin secretion in INS-1 cells
- 2019
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Ingår i: Islets. - : Informa UK Limited. - 1938-2014 .- 1938-2022. ; 11:1, s. 10-20
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the expression and function of Retinoic acid-related orphan receptors (RORA, B, and C) in pancreatic β cells. Here in, we utilized cDNA microarray and RNA sequencing approaches to investigate the expression pattern of ROR receptors in normal and diabetic human pancreatic islets. Possible correlations between RORs expression and HbA 1c levels as well as insulin secretory capacity in isolated human islets were evaluated. The impact of RORB and RORC expression on insulin secretion in INS-1 (832/13) cells was validated as well. While RORA was the highest expressed gene among the three RORs in human islet cells, RORC was the highest expressed in INS-1 cells (832/13) and while RORB was the lowest expressed gene in human islet cells, RORA was the highest expressed in INS-1 cells (832/13). The expression of RORB and RORC was significantly lower in diabetic/hyperglycemic donors as compared with non-diabetic counterparts. Furthermore, while the expression of RORB correlated positively with insulin secretion and negatively with HbA 1c , that of RORC correlated negatively with HbA 1c . The expression pattern of RORA did not correlate with either of the two parameters. siRNA silencing of RORB or RORC in INS-1 (832/13) cells resulted in a significant downregulation of insulin mRNA expression and insulin secretion. These findings suggest that RORB and RORC are part of the molecular cascade that regulates insulin secretion in pancreatic β cells; and insight that provides for further work on the potential therapeutic utility of RORB and RORC genes in β cell dysfunction in type 2 diabetes.
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