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Regulation of gene expression by alternative polyadenylation and mRNA instability in hyperglycaemic mesangial cells
N Abdel Wahab1, J Gibbs, R M Mason
1Molecular Pathology Section, Division of Biomedical Sciences, Imperial College School of Medicine, BMS Building, South Kensington, London SW7 2AZ, U.K.
Abstract:
We have used mRNA differential display to identify a novel high-glucose-regulated gene (HGRG-14) in human mesangial cells cultured for up to 21 days in 30 mM d-glucose. The mRNA of HGRG-14 seems to be regulated post-transcriptionally and encodes a small polypeptide of molecular mass 13 kDa. The native protein occurs as a dimer. The recombinant protein is a substrate for casein kinase II kinase. At high glucose concentrations, HGRG-14 protein levels decrease. This correlates with the appearance of a long form of HGRG-14 mRNA under high-glucose conditions. This form has a long 3' untranslated region containing several ATTTA RNA-destabilizing sequences and has a short half-life. A truncated, more stable mRNA that lacks the long 3' untranslated region is produced at 4 mM d-glucose. The switch from the truncated to the long-form transcript is detected within 2 h of exposure to 30 mM d-glucose, indicating that hyperglycaemic conditions have an acute effect on HGRG-14 mRNA processing.
Insights
High glucose levels acutely affect human mesangial cells by altering HGRG-14 gene expression. This leads to decreased HGRG-14 protein via a novel post-transcriptional regulation mechanism involving mRNA processing.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Hyperglycemia is a hallmark of diabetes mellitus and contributes to diabetic nephropathy.
- Human mesangial cells play a crucial role in kidney function and are affected by high glucose concentrations.
- Understanding the molecular mechanisms underlying glucose-induced cellular changes is vital for developing therapeutic strategies.
Purpose of the Study:
- To identify and characterize novel genes regulated by high glucose in human mesangial cells.
- To elucidate the post-transcriptional regulatory mechanisms of the identified high-glucose-regulated gene (HGRG-14).
- To investigate the impact of hyperglycemic conditions on HGRG-14 mRNA processing and stability.
Main Methods:
- mRNA differential display was employed to identify differentially expressed genes.
- Human mesangial cells were cultured under varying d-glucose concentrations (4 mM and 30 mM).
- Analysis of mRNA processing, 3' untranslated regions, RNA stability, and protein expression was performed.
Main Results:
- A novel high-glucose-regulated gene, HGRG-14, was identified in human mesangial cells.
- HGRG-14 mRNA is regulated post-transcriptionally, leading to decreased protein levels under high glucose.
- High glucose induces a switch to a long HGRG-14 mRNA form with a destabilizing 3' UTR, reducing mRNA half-life within 2 hours.
Conclusions:
- Hyperglycemic conditions trigger an acute and specific alteration in HGRG-14 mRNA processing in human mesangial cells.
- The identified HGRG-14 gene and its regulatory mechanism offer potential targets for understanding and treating diabetic nephropathy.
- Post-transcriptional regulation, particularly via 3' UTR elements, plays a significant role in cellular responses to high glucose.