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J Biol Chem 2013 Jun 7;288(23):16308-20

Heat Shock Protein 90 Functions to Stabilize and Activate the Testis-specific Serine/Threonine Kinases, a Family of Kinases Essential for Male Fertility.

Jha KN, Coleman AR, Wong L, Salicioni AM, Howcroft E, Johnson GR


Spermiogenesis is characterized by a profound morphological differentiation of the haploid spermatid into spermatozoa. The testis-specific serine/threonine kinases (TSSKs) comprise a family of post-meiotic kinases expressed in spermatids, are critical to spermiogenesis and are required for male fertility in mammals. To explore the role of HSP90 in regulation of TSSKs, the stability and catalytic activity of epitope-tagged murine TSSKs were assessed in 293T and COS-7 cells. TSSK1, 2, 4, and 6 (SSTK) were all found to associate with HSP90 and pharmacological inhibition of HSP90 function using the highly specific drugs 17-AAG, SNX-5422, or NVP-AUY922 reduced TSSK protein levels in cells. The attenuation of HSP90 function abolished the catalytic activities of TSSK4 and 6, but did not significantly alter the specific activities of TSSK1 and 2. Inhibition of HSP90 resulted in increased TSSK ubiquitination and proteasomal degradation indicating that HSP90 acts to control ubiquitin-mediated catabolism of the TSSKs. To study HSP90 and TSSKs in germ cells a mouse primary spermatid culture model was developed and characterized. Using specific antibodies against murine TSSK2 and 6, it was demonstrated that HSP90 inhibition resulted in a marked decrease of the endogenous kinases in spermatids. Together, our findings demonstrate that HSP90 plays a broad and critical role in stabilization and activation of the TSSK family of protein kinases.

Category: Journal Article
PubMed ID: #23599433 DOI: 10.1074/jbc.M112.400978
Includes FDA Authors from Scientific Area(s): Drugs
Entry Created: 2013-04-20 Entry Last Modified: 2013-08-13