Figure 1. PTP1B regulates brown adipocyte differentiation.

A) Immunoblots of human (h) and mouse (m) PTP1B expression in immortalized brown adipocytes from wild type mice (Con), PTP1B knockout (KO) mice, and KO cells reconstituted with hPTP1B (WT), substrate-trapping (D/A), and sumoylation-resistant (K/R) hPTP1B mutants. Blots were probed with anti-Tubulin antibodies as a control for loading. B) Schematic depicting timeline of cell differentiation and oil red O staining. C) Brown adipose precursor cells were grown to confluence, then differentiation was induced as described in Methods. At various stages of differentiation, cells were fixed and stained with oil red O, then the dye was extracted and its absorbance (520 nm) quantitated (D). Graph represents data from nine independent experiments, and data are expressed as mean ± SEM. (**) indicates significant difference between K/R and WT, KO and D/A cells.