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SUN-718 Reciprocal Regulation of miR-375 and ICER in Pancreatic Beta Cells

MicroRNA-375 (miR-375) is overexpressed in people with type 2 diabetes (T2D) and has been linked to decreased insulin secretion and beta cell proliferation. Investigation into the transcription factor inducible cAMP early repressor (ICER) as an intermediate regulator of miR-375 was proposed because...

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Autores principales: Frias, Stephanye, Nielsen, Ryan, Perez, Isis, Garcia, Jesse, Keller, David M
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7209189/
http://dx.doi.org/10.1210/jendso/bvaa046.1898
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author Frias, Stephanye
Nielsen, Ryan
Perez, Isis
Garcia, Jesse
Keller, David M
author_facet Frias, Stephanye
Nielsen, Ryan
Perez, Isis
Garcia, Jesse
Keller, David M
author_sort Frias, Stephanye
collection PubMed
description MicroRNA-375 (miR-375) is overexpressed in people with type 2 diabetes (T2D) and has been linked to decreased insulin secretion and beta cell proliferation. Investigation into the transcription factor inducible cAMP early repressor (ICER) as an intermediate regulator of miR-375 was proposed because both are regulated by the cAMP pathway. This overexpression of miR-375 in T2D led us to hypothesize that beta cells with elevated and reduced levels of miR-375 will result in decreased and increased glucose-stimulated insulin secretion (GSIS), respectively. Results showed that when miR-375 was overexpressed, GSIS decreased by 61% when compared to a control in 25 mM glucose. Results showed that when miR-375 was inhibited, GSIS increased 6% when compared to a control in 25 mM glucose. In human islets, we found that inhibiting miR-375 led to an average 19% increase in GSIS, though due to the variability of human tissue these data were not significant (N=5). To investigate ICER’s binding affinity to the miR-375 promoter, a luciferase reporter assay was conducted. HEK-293 (human embryonic kidney) cells that were transfected with a luciferase reporter plasmid containing a cAMP recognition element (CRE) and a plasmid driving the overexpression of ICER had a 75% decrease when compared to our control (P<0.05). When transiently-expressed ICER was knocked down via siRNA, promoter activity increased by 13.1-fold (P< 0.05). Using a chromatin immunoprecipitation assay we found that an ICER antibody pulled down the rat miR-375 promoter an average of 13-fold compared with a control antibody (N=2). Additionally, because of a sequence alignment showing possible binding of miR-375 to the human ICER transcript we hypothesize that the two are in a negative feedback loop and can regulate each other’s expression. To investigate the double negative feedback loop a plasmid was constructed containing the GFP reporter gene and either the human or rodent ICER 3’UTR predicted miR-375 binding site. The GFP reporter assay was conducted to determine if miR-375 binds to ICER’s microRNA recognition element (MRE) in a species-specific way. In our GFP reporter experiment, data shows there is a 50% reporter gene decrease between our negative control and the human ICER MRE (N=4, P=0.017). Understanding microRNA gene regulation in the pancreas may have important implications for patients with T2D. MiR-375 may have the ability to interact with human ICER in a double negative feedback loop in the cAMP second messenger pathway, which will further clarify cellular mechanisms to potentially improve T2D drugs.
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spelling pubmed-72091892020-05-13 SUN-718 Reciprocal Regulation of miR-375 and ICER in Pancreatic Beta Cells Frias, Stephanye Nielsen, Ryan Perez, Isis Garcia, Jesse Keller, David M J Endocr Soc Genetics and Development (including Gene Regulation) MicroRNA-375 (miR-375) is overexpressed in people with type 2 diabetes (T2D) and has been linked to decreased insulin secretion and beta cell proliferation. Investigation into the transcription factor inducible cAMP early repressor (ICER) as an intermediate regulator of miR-375 was proposed because both are regulated by the cAMP pathway. This overexpression of miR-375 in T2D led us to hypothesize that beta cells with elevated and reduced levels of miR-375 will result in decreased and increased glucose-stimulated insulin secretion (GSIS), respectively. Results showed that when miR-375 was overexpressed, GSIS decreased by 61% when compared to a control in 25 mM glucose. Results showed that when miR-375 was inhibited, GSIS increased 6% when compared to a control in 25 mM glucose. In human islets, we found that inhibiting miR-375 led to an average 19% increase in GSIS, though due to the variability of human tissue these data were not significant (N=5). To investigate ICER’s binding affinity to the miR-375 promoter, a luciferase reporter assay was conducted. HEK-293 (human embryonic kidney) cells that were transfected with a luciferase reporter plasmid containing a cAMP recognition element (CRE) and a plasmid driving the overexpression of ICER had a 75% decrease when compared to our control (P<0.05). When transiently-expressed ICER was knocked down via siRNA, promoter activity increased by 13.1-fold (P< 0.05). Using a chromatin immunoprecipitation assay we found that an ICER antibody pulled down the rat miR-375 promoter an average of 13-fold compared with a control antibody (N=2). Additionally, because of a sequence alignment showing possible binding of miR-375 to the human ICER transcript we hypothesize that the two are in a negative feedback loop and can regulate each other’s expression. To investigate the double negative feedback loop a plasmid was constructed containing the GFP reporter gene and either the human or rodent ICER 3’UTR predicted miR-375 binding site. The GFP reporter assay was conducted to determine if miR-375 binds to ICER’s microRNA recognition element (MRE) in a species-specific way. In our GFP reporter experiment, data shows there is a 50% reporter gene decrease between our negative control and the human ICER MRE (N=4, P=0.017). Understanding microRNA gene regulation in the pancreas may have important implications for patients with T2D. MiR-375 may have the ability to interact with human ICER in a double negative feedback loop in the cAMP second messenger pathway, which will further clarify cellular mechanisms to potentially improve T2D drugs. Oxford University Press 2020-05-08 /pmc/articles/PMC7209189/ http://dx.doi.org/10.1210/jendso/bvaa046.1898 Text en © Endocrine Society 2020. http://creativecommons.org/licenses/by-nc-nd/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs licence (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reproduction and distribution of the work, in any medium, provided the original work is not altered or transformed in any way, and that the work is properly cited. For commercial re-use, please contact journals.permissions@oup.com
spellingShingle Genetics and Development (including Gene Regulation)
Frias, Stephanye
Nielsen, Ryan
Perez, Isis
Garcia, Jesse
Keller, David M
SUN-718 Reciprocal Regulation of miR-375 and ICER in Pancreatic Beta Cells
title SUN-718 Reciprocal Regulation of miR-375 and ICER in Pancreatic Beta Cells
title_full SUN-718 Reciprocal Regulation of miR-375 and ICER in Pancreatic Beta Cells
title_fullStr SUN-718 Reciprocal Regulation of miR-375 and ICER in Pancreatic Beta Cells
title_full_unstemmed SUN-718 Reciprocal Regulation of miR-375 and ICER in Pancreatic Beta Cells
title_short SUN-718 Reciprocal Regulation of miR-375 and ICER in Pancreatic Beta Cells
title_sort sun-718 reciprocal regulation of mir-375 and icer in pancreatic beta cells
topic Genetics and Development (including Gene Regulation)
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7209189/
http://dx.doi.org/10.1210/jendso/bvaa046.1898
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