Adipocytes, or fat cells,  are  important  endocrine  and  metabolic  cells  critical  for  systemic  insulin sensitivity and both adipose excess and insufficiency are associated with adverse metabolic function. Mature adipocytes develop in a process called adipogenesis , whereby preadipocyte precursors differentiate into lipid laden fat cells. Adipogenesis  is  driven  by  a  network  of  transcriptional  regulators active at different stages of cell differentiation.

Rabiee, Jensen and colleagues  hypothesized that upon induction of adipogenesis, protein post-translational modifications (PTMs), in particular phosphorylation, play  a major  role  in  activating  and  propagating  signals  within the transcriptional regulators networks.  They applied mass spectrometry-based  quantitative proteomics and phosphoproteomics to monitor nuclear proteins during the first 4 hours of preadipocyte differentiation which revealed significant changes in the phosphorylation of multiple transcriptional regulators. Adipogenic stimuli increased the nuclear abundance and/or phosphorylation levels of proteins involved in gene expression, cell organization and oxidation-reduction  pathways, whereas  negative  modulators  of  gene  expression,  insulin  stimulated  glucose  uptake,  and  cytoskeletal organization showed the opposite trend. The researchers created a useful kinase-substrate database based on  the  relationship  between  protein  kinases  and  the identified protein  phosphorylation  sites and their results suggest that the cyclin-dependent kinase family and the mitogen activated protein kinase (MAPK) family act as orchestrators of early adipogenesis.