HSP90 Functions to Stabilize and Activate the Testis-Specific Serine/threonine Kinases, a Family of Kinases Essential for Male Fertility.

HSP90 functions to stabilize and activate the testis-specific serine/threonine kinases, a family of kinases essential for male fertility.

J Biol Chem. 2013 Apr 18;
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. HubMed – drug


Mechanisms of Mitochondrial Damage in Keratinocytes by Pemphigus Vulgaris Antibodies.

J Biol Chem. 2013 Apr 18;
Kalantari-Dehaghi M, Chen Y, Deng W, Chernyavsky A, Marchenko S, Wang PH, Grando SA

The development of non-hormonal treatment of pemphigus vulgaris (PV) has been hampered by a lack of clear understanding of the mechanisms leading to keratinocyte (KC) detachment and death in pemphigus. In this study, we sought to identify changes in the vital mitochondrial functions in KCs treated with the sera from PV patients and healthy donors. PV sera significantly increased proton leakage from KCs, suggesting that PV IgGs increase production of reactive oxygen species (ROS). Indeed, measurement of intracellular ROS production showed a drastic increase of cell staining in response to treatment by PV sera, which was confirmed by FACS analysis. Exposure of KCs to PV sera also caused dramatic changes in the mitochondrial membrane potential detected with the JC-1 dye. These changes can trigger the mitochondria-mediated intrinsic apoptosis. While sera from different PV patients elicited unique patterns of mitochondrial damage, the mitochondria-protecting drugs nicotinamide, minocycline and cyclosporine A exhibited a uniform protective effect. Their therapeutic activity was validated in the passive transfer model of PV in neonatal BALB/c mice. The highest efficacy of mitochondrial protection of the combination of these drugs found in mitochondrial assay was consistent with the ability of the same drug combination to abolish acantholysis in mouse skin. These findings provide a theoretical background for clinical reports of the efficacy of mitochondria-protecting drugs in PV patients. Pharmacological protection of mitochondria and/or compensation of an altered mitochondrial function may therefore become a novel approach to development of personalized non-hormonal therapies of patients with this potentially lethal autoimmune blistering disease. HubMed – drug


Regulatory Forum Commentary*: Through the Looking Glass–SENDing the Pathology Data We Have INHAND.

Toxicol Pathol. 2013 Apr 18;
Keenan CM, Goodman DG

During 2011, International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice (INHAND) Global Editorial Steering Committee representatives had discussions with representatives of the Food and Drug Administration (FDA) Center for Drug Evaluation and Research (CDER), Clinical Data Interchange Standards Consortium (CDISC), and the National Cancer Institute (NCI) Enterprise Vocabulary Services (EVS) to examine the potential use of INHAND terminology for SEND (Standard for Exchange of Nonclinical Data) submissions to the FDA. The interest in utilizing the INHAND nomenclature, based on input from industry and government toxicologists as well as information technology specialists, suggests that there will be wide acceptance of INHAND nomenclature. The purpose of this article is 2-fold: (1) to provide a brief historical background on the development of SEND and how it is structured and (2) to discuss the impact of SEND on toxicologic pathology and the role of INHAND. HubMed – drug


Orals in the Bundle: A Policy Framework.

Clin J Am Soc Nephrol. 2013 Apr 18;
Feldman RL, Desmarais MP, Muller JS

Oral prescription drugs for treatment of bone and mineral disorders (phosphate binders and calcimimetics) in patients undergoing dialysis (i.e., those with ESRD) will be integrated into the Medicare Part B ESRD bundled payment system in 2016. Payment will be denied under Medicare Part D. Integrating Part D drugs into Part B payment at this level of scale lacks any policy precedent. Providers and patients have serious concerns about the potential for inadequate funding, and the Centers for Medicare & Medicaid Services (CMS) has been silent about the methods and other critical policy used to guide its decisions. We believe an adequate policy framework to support valuation of the targeted oral drugs depends on use of the most recent available Medicare Part D data, measurement of mean utilization for all target drugs based on a minimum of 6 months of complete data for prescriptions and dialysis treatments, use of appropriate price proxies to monetize drug volume to dialysis provider acquisition cost, adjustment to account for change in adherence due to change in patient out-of-pocket expenses, inclusion of valuation for dispensing and administrative cost, and a mechanism for adjusting payment to future changes in adherence. HubMed – drug