The Protein Kinase C [beta]II Exon Confers mRNA Instability in the Presence of High Glucose Concentrations

• Published in: The Journal of biological chemistry 2003-01, Vol.278 (2), p.1149-1157
• Main Authors: Patel, NA, Eichler, D C, Chappell, D S, Illingworth, P A, Chalfant, CE, Yamamoto, M, Dean, N M, Wyatt, J R, Mebert, K, Watson, JE, Cooper, DR
• Format: Article
• Language: English
• ISSN: 0021-9258

Previous studies showed that short term exposure of cells to high glucose destabilized protein kinase C (PKC) [beta]II mRNA, whereas PKC[beta]I mRNA levels remained unaltered. Because PKC[beta] mRNAs share common sequences other than the PKC[beta]II exon encoding a different carboxyl terminus, we examined PKC[beta]II mRNA for a cis-acting region that could confer glucose-induced destabilization. A [beta]-globin/growth hormone reporter con struct containing the PKC[beta]II exon was transfected into human aorta and rat vascular smooth muscle cells (A10) to follow glucose-induced destabilization. Glucose (25 mM) exposure destabilized PKC[beta]II chimeric mRNA but not control mRNA. Deletion analysis and electrophoretic mobility shift assays followed by UV cross-linking experiments demonstrated that a region introduced by inclusion of the [beta]II exon was required to confer destabilization. Although a cis-acting element mapped to 38 nucleotides within the [beta]II exon was necessary to bestow destabilization, it was not sufficient by itself to confer complete mRNA destabilization. Yet, in intact cells antisense oligonucleotides complementary to this region blocked glucose-induced destabilization. These results suggest that this region must function in context with other sequence elements created by exon inclusion involved in affecting mRNA stability. In summary, inclusion of an exon that encodes PKC[beta]II mRNA introduces a cis-acting region that confers destabilization to the mRNA in response to glucose.