The No-Go and Nonsense-Mediated RNA Decay Pathways Are Regulated by Inflammatory Cytokines in Insulin-Producing Cells and Human Islets and Determine β-Cell Insulin Biosynthesis and Survival

TY - JOUR

T1 - The No-Go and Nonsense-Mediated RNA Decay Pathways Are Regulated by Inflammatory Cytokines in Insulin-Producing Cells and Human Islets and Determine β-Cell Insulin Biosynthesis and Survival

AU - Ghiasi, Seyed Mojtaba

AU - Krogh, Nicolai

AU - Tyrberg, Björn

AU - Mandrup-Poulsen, Thomas

N1 - © 2018 by the American Diabetes Association.

PY - 2018/10

Y1 - 2018/10

N2 - Stress-related changes in b-cell mRNA levels result from a balance between gene transcription and mRNA decay. The regulation of RNA decay pathways has not been investigated in pancreatic b-cells. We found that no-go and nonsense-mediated RNA decay pathway components (RDPCs) and exoribonuclease complexes were expressed in INS-1 cells and human islets. Pelo, Dcp2, Dis3L2, Upf2, and Smg1/5/6/7 were upregulated by inflammatory cytokines in INS-1 cells under conditions where central b-cell mRNAs were downregulated. These changes in RDPC mRNA or corresponding protein levels were largely confirmed in INS-1 cells and rat/ human islets. Cytokine-induced upregulation of Pelo, Xrn1, Dis3L2, Upf2, and Smg1/6 was reduced by inducible nitric oxide synthase inhibition, as were endoplasmic reticulum (ER) stress, inhibition of Ins1/2 mRNA, and accumulated insulin secretion. Reactive oxygen species inhibition or iron chelation did not affect RDPC expression. Pelo or Xrn1 knockdown (KD) aggravated, whereas Smg6 KD ameliorated, cytokine-induced INS-1 cell death without affecting ER stress; both increased insulin biosynthesis and medium accumulation but not glucose-stimulated insulin secretion in cytokine-exposed INS-1 cells. In conclusion, RDPCs are regulated by inflammatory stress in b-cells. RDPC KD improved insulin biosynthesis, likely by preventing Ins1/2 mRNA clearance. Pelo/Xrn1 KD aggravated, but Smg6 KD ameliorated, cytokine-mediated b-cell death, possibly through prevention of proapoptotic and antiapoptotic mRNA degradation, respectively.

AB - Stress-related changes in b-cell mRNA levels result from a balance between gene transcription and mRNA decay. The regulation of RNA decay pathways has not been investigated in pancreatic b-cells. We found that no-go and nonsense-mediated RNA decay pathway components (RDPCs) and exoribonuclease complexes were expressed in INS-1 cells and human islets. Pelo, Dcp2, Dis3L2, Upf2, and Smg1/5/6/7 were upregulated by inflammatory cytokines in INS-1 cells under conditions where central b-cell mRNAs were downregulated. These changes in RDPC mRNA or corresponding protein levels were largely confirmed in INS-1 cells and rat/ human islets. Cytokine-induced upregulation of Pelo, Xrn1, Dis3L2, Upf2, and Smg1/6 was reduced by inducible nitric oxide synthase inhibition, as were endoplasmic reticulum (ER) stress, inhibition of Ins1/2 mRNA, and accumulated insulin secretion. Reactive oxygen species inhibition or iron chelation did not affect RDPC expression. Pelo or Xrn1 knockdown (KD) aggravated, whereas Smg6 KD ameliorated, cytokine-induced INS-1 cell death without affecting ER stress; both increased insulin biosynthesis and medium accumulation but not glucose-stimulated insulin secretion in cytokine-exposed INS-1 cells. In conclusion, RDPCs are regulated by inflammatory stress in b-cells. RDPC KD improved insulin biosynthesis, likely by preventing Ins1/2 mRNA clearance. Pelo/Xrn1 KD aggravated, but Smg6 KD ameliorated, cytokine-mediated b-cell death, possibly through prevention of proapoptotic and antiapoptotic mRNA degradation, respectively.

KW - Animals

KW - Apoptosis/drug effects

KW - Blotting, Northern

KW - Blotting, Western

KW - Cell Line

KW - Cell Survival/drug effects

KW - Cytokines/metabolism

KW - Exoribonucleases/metabolism

KW - Humans

KW - Insulin/metabolism

KW - Insulin-Secreting Cells/metabolism

KW - Nuclear Proteins/metabolism

KW - Phosphatidylinositol 3-Kinases/metabolism

KW - Phosphorylation/drug effects

KW - RNA/metabolism

KW - RNA Stability/genetics

KW - Rats

KW - Reverse Transcriptase Polymerase Chain Reaction

KW - Signal Transduction/drug effects

UR - http://www.scopus.com/inward/record.url?scp=85054775149&partnerID=8YFLogxK

U2 - 10.2337/db18-0073

DO - 10.2337/db18-0073

M3 - Journal article

C2 - 30065031

SN - 0012-1797

VL - 67

SP - 2019

EP - 2037

JO - Diabetes

JF - Diabetes

IS - 10

ER -