FIG. 1.

STZ-induced diabetes produces a shift from cap-dependent to cap-independent translation. Liver supernatant fractions (1,000g) were prepared from transgenic mice after 4 weeks of STZ-induced diabetes or from control mice treated with vehicle only as described in research design and methods. A: Diagram of bicistronic transgene expressed by transgenic mice. B: Translation of LucR occurs in a cap-dependent manner. C: Translation of LucF is regulated by the FGF-2 IRES in a cap-independent manner. D: Ratio of LucF to LucR activity in liver supernatant fraction represents the relative translation from each reporter. The interaction of 4E-BP1 (E) and eIF4G (F) with eIF4E was examined by immunoprecipitating eIF4E and measuring the amount of 4E-BP1 and eIF4G in the immunoprecipitate (IP) by Western blot analysis. Phosphorylation (G) and O-GlcNAcylation (H) of 4E-BP1 as well as total eIF4E (I) and 4E-BP1 (J) content was measured by treating supernatant fractions with λ-phosphatase (PPase) followed by Western blot analysis as previously described (11). Values are means ± SE for a single experiment (n = 8). Statistical significance of the differences between means was assessed by Student t test and is denoted by *P < 0.05.