PTPIP51 interaction with PTP1B and 14-3-3β in adipose tissue of insulin-resistant mice.

We investigated the expression of protein tyrosine phosphatase-interacting protein 51 (PTPIP51) and its interaction with protein tyrosine phosphatase 1B (PTP1B) and 14-3-3β in mice exhibiting insulin resistance and obesity. A total of 20 mice were included in the study. Eight control animals were fed a normal standard diet, six animals were fed a high-fat diet and six animals were submitted to a treadmill training parallel to the feeding of a high-fat diet. After 10 weeks, a glucose tolerance test was performed and abdominal adipose tissue samples of the animals were collected. PTPIP51 protein was identified in the adipocytes of all samples. PTPIP51 interacted with PTP1B and with 14-3-3β protein. Compared with untrained mice fed a standard diet, the interaction of PTPIP51 with PTP1B was reduced in high-fat diet-fed animals. The highest interaction of PTPIP51 with 14-3-3β was seen in trained animals on high-fat diet, whereas untrained animals on high-fat diet displayed lowest values. PTPIP51 is expressed in adipose tissue of humans, rats and mice. Obesity with enhanced insulin resistance resulted in a reduction of PTPIP51 levels in adipocytes and influenced the interactions with PTP1B and 14-3-3β. The interaction of PTPIP51 with PTP1B suggests a regulatory function of PTPIP51 in insulin receptor signal transduction. The interaction of PTPIP51 with 14-3-3β, especially in trained individuals, hints to an involvement of PTPIP51 in the downstream regulation of insulin action.