Roles of Macrophage Colony Stimulating Factor in White and Brown Adipocytes

Abstract

Macrophage colony stimulating factor (M-CSF), commonly known as CSF1, is a cytokine produced by osteoblast cells, and is well known for its important role in differentiation of osteoclasts and white adipocyte hyperplasia. However, the role of M-CSF in lipid metabolic activity is lacking insight. In the current study, we explore unidentified actions of M-CSF in adipocytes. Levels of M-CSF were determined for white and brown adipose tissues and cells, and the expression levels of the important protein markers in lipid metabolism were evaluated through immunoblot analysis, subsequent to blocking M-CSF in fat cells by silencing its receptor Csf1r. Interestingly, we observed presence of M-CSF in brown fat cells. In addition, the lack of M-CSF in HIB1B cells attenuated the expressions of protein markers responsible for lipid metabolism in the brown adipocytes. Further, deficiency of M-CSF resulted in decreased adipogenesis along with reduced expression of lipogenic markers for both white and brown adipocytes. Moreover, lipid metabolism was balanced by M-CSF via the PPARγ-mediated LPL activity in white adipocytes. Taken together, the results from this study indicate that MCSF is an important regulatory protein in both white and brown adipocytes.