FIGURE 1.

HDAC inhibitors block adipogenesis in vitro. A, deletion of HDAC3 in cardiomyocytes leads to cardiomyopathy as shown by hematoxylin and eosin staining of histological sections of wild-type and HDAC3-null hearts. B, lipid accumulation in heart tissue lacking HDAC3 visualized by staining with Oil Red O (ORO) following a 24-h fasting. Red staining indicates the presence of neutral lipids. C, treatment of pre-adipocytes (3T3-L1 cells) with a hormone inducer mixture for 8 days led to effective adipogenesis, which can be monitored by staining with ORO. Adipocyte differentiation is completely blocked by 100 nm TSA. Size bars: 60 μm. D, up-regulation of adipogenic marker genes in induced 3T3-L1 cells is blocked by incubation with TSA, Scriptaid, and SAHA but not sodium butyrate as shown by RT-PCR for different markers of terminally differentiated adipocytes, such as hormone-sensitive lipase (LIPE), adiponectin (AdipoQ), and adipocyte lipid-binding protein (aP2). Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was detected as a control. E, quantification of adipogenesis in 3T3-L1 cells as shown in panel C by measuring the absorbance of resolubilized ORO. Treatment of 3T3-L1 cells induced to differentiate with 100 nm TSA causes the almost complete block of adipocyte differentiation. F and G, reduced adipocyte differentiation at various concentrations of TSA shows a dose-response correlation. H, treatment of 3T3-L1 cells with Scriptaid or SAHA causes the block of adipocyte differentiation in a dose-response manner. On the contrary, treatment of 3T3-L1 cells with the short-chain fatty acid sodium butyrate enhances lipid accumulation.