CIDE-A gene expression is decreased in white adipose tissue of growth hormone receptor/binding protein gene disrupted mice and with high-fat feeding of normal mice

Abstract

Growth hormone's (GH) lipolytic activity in white adipose tissue (WAT) results in decreased body fat in giant GH transgenic mice and increased subcutaneous fat in dwarf growth hormone receptor/binding protein gene-disrupted mice (GHR -/-). We therefore hypothesized that GH action would affect expression of CIDE-A (cell-death-inducing DFF45-like effector-A), a protein found in white adipose tissue (WAT) and involved in lipid metabolism. CIDE-A RNA levels were determined in subcutaneous, retroperitoneal and epididymal adipose tissue isolated from wild-type and GHR -/- mice. The adipose tissue was also analyzed for adipocyte size. We determined that the lack of GH action has depot-specific effects on the levels of CIDE-A RNA and affected adipocyte cell size. CIDE-A expression is significantly reduced in GHR -/- subcutaneous fat compared to wild-type but is not altered in retroperitoneal or epididymal fat. Likewise, adipocytes are significantly enlarged in GHR -/- subcutaneous adipose tissue relative wild-type mice. A high-fat diet also influenced the level of CIDE-A RNA in mouse adipose tissue. The high-fat diet significantly reduced CIDE-A expression in wild-type subcutaneous fat but did not alter CIDE-A expression in subcutaneous fat of GHR -/- mice. The diet also reduced CIDE-A expression in wild-type retroperitoneal fat but the levels of CIDE-A in epididymal fat were unchanged. In contrast, the high-fat diet reduced CIDE-A expression in both retroperitoneal and epididymal fat of GHR -/- mice. These data demonstrate that CIDE-A levels are reduced in two different mouse models of obesity and this reduction may contribute to altered lipid metabolism.