This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Xie, J. Articles by Roberson, M. S. Search for Related Content PubMed PubMed Citation Articles by Xie, J. Articles by Roberson, M. S.

Analysis of the Calcium-Dependent Regulation of Proline-Rich Tyrosine Kinase 2 by Gonadotropin-Releasing Hormone

Department of Biomedical Sciences (J.X., K.H.A., A.M., K.A.B., S.P.B., A.M.N., M.S.R.), Cornell University, Ithaca, New York 14853; and Division of Molecular Medicine and Genetics (J.L.G.), University of Michigan, Ann Arbor, Michigan 48109

Address all correspondence and requests for reprints to: Mark S. Roberson, Ph.D., T4-018 Veterinary Research Tower, Department of Biomedical Sciences, Cornell University, Ithaca, New York 14853. E-mail: msr14{at}cornell.edu.

Calcium influx through L-type voltage-gated calcium channels (VGCC) is required for ERK activation induced by GnRH in pituitary gonadotropes. The current studies investigate VGCC-sensitive catalytic activities that may lie upstream of ERKs within the GnRH signaling network. Ion exchange fractionation of T3-1 cell lysates subjected to anti-phosphotyrosine Western blot analysis revealed a nifedipine-sensitive activity that colocalized with proline-rich tyrosine kinase (Pyk) 2 immunoreactivity. Phosphorylated Pyk2 was present in T3-1 cells after GnRH agonist administration for a time course that lasted up to 4 h. Pyk2 phosphorylation was also evident in gonadotropes in vivo after administration of a bolus of GnRH. Knockdown of Pyk2 using specific small interfering RNAs revealed that Pyk2 contributed to modulation of GnRH-induced ERK but not c-Jun N-terminal kinase activation. Using pharmacological approaches, calmodulin (Cam) was also demonstrated to be required for the phosphorylation of Pyk2. Pyk2 was shown to bind specifically to a Cam agarose affinity column in a calcium-dependent manner, suggesting Cam and Pyk2 are capable of forming a complex. Specific mutation of a putative Cam binding motif within the catalytic domain of Pyk2 blocked association with Cam and uncoupled Pyk2’s ability to activate ERK-dependent gene transcription. Thus, GnRH induces Pyk2 tyrosine phosphorylation dependent upon calcium flux within gonadotropes. Furthermore, association of Pyk2 and Cam may be required to mediate the effects of calcium on Pyk2 phosphorylation and subsequent activation of ERKs by GnRH.

This article has been cited by other articles:

				J. C. Loftus, Z. Yang, N. L. Tran, J. Kloss, C. Viso, M. E. Berens, and C. A. Lipinski The Pyk2 FERM domain as a target to inhibit glioma migration Mol. Cancer Ther., June 1, 2009; 8(6): 1505 - 1514. [Abstract] [Full Text] [PDF]