Anti-CIDEB monoclonal antibody, clone 3B20

Both insulin and the cell death-inducing DNA fragmentation factor-alpha-like effector (CIDE) family play important roles in apoptosis and lipid droplet formation. However, regulation of the CIDE family by insulin and the contribution of the CIDE family to insulin actions remain unclear. Here, we investigated whether insulin regulates expression of the CIDE family and which subtypes contribute to insulin-induced anti-apoptosis and lipid droplet formation in human adipocytes. Insulin decreased CIDEA and increased CIDEC but not CIDEB mRNA expression. Starvation-induced apoptosis in adipocytes was significantly inhibited when insulin decreased the CIDEA mRNA level. Small interfering RNA-mediated depletion of CIDEA inhibited starvation-induced apoptosis similarly to insulin and restored insulin deprivation-reduced adipocyte number, whereas CIDEC depletion did not. Lipid droplet size of adipocytes was increased when insulin increased the CIDEC mRNA level. In contrast, insulin-induced enlargement of lipid droplets was markedly abrogated by depletion of CIDEC but not CIDEA. Furthermore, depletion of CIDEC, but not CIDEA, significantly increased glycerol release from adipocytes. These results suggest that CIDEA and CIDEC are novel genes regulated by insulin in human adipocytes and may play key roles in the effects of insulin, such as antiapoptosis and lipid droplet formation.-Minoru, I., M. Nagasawa, T. Hara, T. Ide, and K. Murakami. Differential roles of CIDEA and CIDEC in insulin-induced anti-apoptosis and lipid droplet formation in human adipocytes. J. Lipid Res. 2010. 51: 1676-1684.

Clear cell renal cell carcinoma (ccRCC) is the major and aggressive subtype of renal cell carcinoma. It is known to derive its histologic appearance from accumulation of abundant lipids and glycogens. The cell death-inducing DFF45-like effector (CIDE) family has been characterized as the lipid droplet proteins involved in the metabolism of lipid storage droplets. The purpose of this study was to evaluate the expression of CIDE proteins in ccRCC cells and to investigate their prognostic significance. We examined consecutive patients with sporadic ccRCC, who underwent nephrectomy, to measure their mRNA and protein expression of CIDE proteins. We found that Cidec and ADRP expression were significantly up-regulated in ccRCC, compared with normal kidney tissues. Cideb was down-regulated. We also found that Cideb was expressed more in low-grade ccRCC than in high-grade tumors. To further clarify the relationship between Cideb expression and patient prognosis, we evaluated 57 ccRCC patients followed up for 120 months. Reduced ccRCC Cideb expression was associated with a higher Fuhrman nuclear grade. Patients with high Cideb expression had better overall survival rate than those with low expression (p < 0.05). Cideb expression was an independent predictor of survival (p = 0.001). Although the biologic function of Cideb in ccRCC remains unknown, the expression level of Cideb might be a novel predictor of prognosis in ccRCC.