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Khalique A, Mohammed AK, Al-khadran NM, Gharaibeh MA, Abu-Gharbieh E, El-Huneidi W, Sulaiman N, Taneera J. Reduced Retinoic Acid Receptor Beta (Rarβ) Affects Pancreatic β-Cell Physiology. Biology (Basel) 2022; 11:biology11071072. [PMID: 36101450 PMCID: PMC9312298 DOI: 10.3390/biology11071072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/15/2022] [Accepted: 07/15/2022] [Indexed: 12/02/2022]
Abstract
Various studies have suggested a link between vitamin A (VA), all-trans-retinol, and type 2 diabetes (T2D). However, the functional role/expression of vitamin A receptors (Rarα, β, and γ) in pancreatic β-cells is not clear yet. Accordingly, we performed a series of bioinformatics, molecular and functional experiments in human islet and INS-1 cells to evaluate the role of Rarβ on insulin secretion and pancreatic β-cell function. Microarray and RNA-sequencing (RAN-seq) expression analysis showed that RARα, β, and γ are expressed in human pancreatic islets. RNA-seq expression of RARβ in diabetic/hyperglycemic human islets (HbA1c ≥ 6.3%) revealed a significant reduction (p = 0.004) compared to nondiabetic/normoglycemic cells (HbA1c < 6%). The expression of RARβ with INS and PDX1 showed inverse association, while positive correlations were observed with INSR and HbA1c levels. Exploration of the T2D knowledge portal (T2DKP) revealed that several genetic variants in RARβ are associated with BMI. The most associated variant is rs6804842 (p = 1.2 × 10−25). Silencing of Rarβ in INS-1 cells impaired insulin secretion without affecting cell viability or apoptosis. Interestingly, reactive oxygen species (ROS) production levels were elevated and glucose uptake was reduced in Rarβ-silenced cells. mRNA expression of Ins1, Pdx1, NeuroD1, Mafa, Snap25, Vamp2, and Gck were significantly (p < 0.05) downregulated in Rarβ-silenced cells. For protein levels, Pro/Insulin, PDX1, GLUT2, GCK, pAKT/AKT, and INSR expression were downregulated considerably (p < 0.05). The expression of NEUROD and VAMP2 were not affected. In conclusion, our results indicate that Rarβ is an important molecule for β-cell function. Hence, our data further support the potential role of VA receptors in the development of T2D.
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Affiliation(s)
- Anila Khalique
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
| | - Abdul Khader Mohammed
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
| | - Nujood Mohammed Al-khadran
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates;
| | - Mutaz Al Gharaibeh
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
| | - Eman Abu-Gharbieh
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates
| | - Waseem El-Huneidi
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates;
| | - Nabil Sulaiman
- Department of Family Medicine, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates;
| | - Jalal Taneera
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; (A.K.); (A.K.M.); (M.A.G.); (E.A.-G.); (W.E.-H.)
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates;
- Correspondence: ; Tel.: +97-165-057-743
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