Current Research

The net cellular level of tyrosine phosphorylation is regulated by the intrinsic and opposing activities of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs).

Protein tyrosine phosphorylation mediates numerous fundamental physiological events such as mitogenesis, differentiation, cell movement and apoptosis. Our laboratory is interested in how PTPs participate in the regulation of these cellular processes. In order to decipher how PTPs regulate mammalian cell signaling we use a broad range of approaches from molecular biology to mouse genetic strategies.

SHP-2 is a ubiquitously expressed PTP containing tandem SH2 domains. We have been interested in understanding the role of SHP-2 in skeletal muscle growth and differentiation. We have shown that SHP-2 is critical for growth factor signaling in cultured muscle cells. The activity of SHP-2 also is important for cultured muscle cells to differentiate into multinucleated myotubes. Our research efforts are now focused on understanding the developmental and post-developmental roles of SHP-2 in skeletal muscle using mouse models.

In virtually all cases, the catalytic activity of SHP-2 is required for normal cellular function. However, the substrates that are dephosphorylated by SHP-2 are largely unknown. To identify SHP-2 substrates, we are using proteomic approaches in conjunction with mutants of SHP-2 that selectively bind to its substrate.

The activation of the MAPKs is critical for the control of a multitude of biological processes. We are interested in how the MAPKs are regulated by a family of PTPs known as MAPK phosphatases (MKPs) that inactivate the MAPKs by dephosphorylation. We are using mouse genetic approaches to study the role of MKP-1 invivo.

Calcium is an important mediator of intracellular signal transduction. We are interested in how PTPs integrate with calcium signaling pathways in the cytoplasm and nucleus. In order to study the integrated role of PTPs and calcium in the nucleus and cytoplasm, we have developed tools to selectively buffer calcium either in the nucleus or cytoplasm independently. We are employing these targeted calcium buffering tools to determine the compartmental affects of calcium on PTP function.