Adipocyte differentiation

Adipocyte differentiation is a highly controlled process that has been extensively studied for the last 25 years. Two different kinds of in vitro experimental models, essential in determining the mechanisms involved in adipocyte proliferation, differentiation and adipokine secretion, are currently available: preadipocyte cell lines, already committed to the adipocyte lineage, and multipotent stem cell lines, able to commit to different lineages including adipose, bone and muscle lineage. Many different events contribute to the commitment of a mesenchymal stem cell into the adipocyte lineage, including the coordination of a complex network of transcription factors, cofactors and signalling intermediates from numerous pathways. New fat cells constantly arise from a preexisting population of undifferentiated progenitor cells or through the dedifferentiation of adipocytes to preadipocytes, which then proliferate and redifferentiate into mature adipocytes. Analysis of adipocyte turnover has shown that adipocytes are a dynamic and highly regulated population of cells. Adipogenesis is a multi-step process involving a cascade of transcription factors and cell-cycle proteins regulating gene expression and leading to adipocyte development. Several positive and negative regulators of this network have been elucidated in recent years. This review is focused in the main molecular and cellular processes associated with adipocyte differentiation, including transcriptional factors and cofactors and extranuclear modulators. The role of epigenetic factors, microRNAs and chronobiology in adipogenesis is also summarized.