title: Heat shock protein 90 functions to stabilize and activate the testis-specific serine/threonine kinases, a family of kinases essential for male fertility.
abstract: 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 heat shock protein 90 (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 (small serine/threonine kinase) 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.
authors.affiliation: Division of Therapeutic Proteins, Center for Drug Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892. Electronic address: kula.jha@fda.hhs.gov.
authors.forename: Kula N
authors.initials: KN
authors.lastname: Jha
authors.affiliation: Division of Therapeutic Proteins, Center for Drug Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892.
authors.forename: Alyssa R
authors.initials: AR
authors.lastname: Coleman
authors.affiliation: Division of Therapeutic Proteins, Center for Drug Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892.
authors.forename: Lily
authors.initials: L
authors.lastname: Wong
authors.affiliation: Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, Massachusetts 01003.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Salicioni
authors.affiliation: Division of Therapeutic Proteins, Center for Drug Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Howcroft
authors.affiliation: Division of Therapeutic Proteins, Center for Drug Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892. Electronic address: gibbes.johnson@fda.hhs.gov.
authors.forename: Gibbes R
authors.initials: GR
authors.lastname: Johnson
mesh_terms: D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D004795:Enzyme Stability / Q000187:drug effects / Q000235:genetics; D005298:Fertility / Q000187:drug effects / Q000502:physiology*; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D059748:Proteolysis / Q000187:drug effects; D013087:Spermatids / Q000166:cytology / Q000378:metabolism*; D054875:Ubiquitination / Q000187:drug effects / Q000502:physiology
chemical_list: D018841:HSP90 Heat-Shock Proteins; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D046988:Proteasome Endopeptidase Complex
keywords: Hsp90; Kinase; SSTK; Serine/Threonine Protein Kinase; Signal Transduction; Spermatogenesis; Spermiogenesis; TSSK; Testis