Expression of prostatic glutathione-peroxidase (GSH-PO) in the rat treated with a combination of testosterone and 17beta-estradiol.

In order to confirm the relationship between sex hormone administration and glutathione-peroxidase (GSH-PO) in the rat ventral prostate, the levels of GSH-PO mRNA, GSH-PO activity, and lipid peroxide (Thiobarbituric acid: TBA) value in the ventral prostate were investigated. Male Crj: CD (SD) IGS rats were divided into six experimental groups. Group 1 consisted of intact controls. In group 2, rats were sacrificed two days after castration. In groups 3 and 4, rats were subcutaneously administered 1 mg/animal of testosterone daily for three- or seven-day administration two days after castration, respectively. In groups 5 and 6, rats were subcutaneously administered 1 mg/animal of testosterone plus 0.01 mg/animal of 17beta-estradiol (E2) daily for three- or seven-day administration two days after castration, respectively. GSH-PO activity of the ventral prostate homogenate for testosterone or testosterone plus E2 administration to the castrated rat was increased and the TBA value was remarkably decreased. The prostatic GSH-PO mRNA level was diminished in the castrated rat ventral prostate, but was increased by testosterone or testosterone plus E2 administration. In particular, the GSH-PO mRNA level of testosterone plus E2-treated animals was higher than that of testosterone-treated animals. These findings strongly suggest that expression of GSH-PO in the rat ventral prostate is testosterone- or E2-dependent. We speculate that the transcription of prostatic GSH-PO mRNA was regulated by testosterone or E2 and de novo synthesis of GSH-PO would thus be regulated at transcription level by testosterone or E2.

Histopathological and immunocytochemical studies of chlormadinone acetate on the rat prostate.

In order to confirm the relationship between glutathione-peroxidase (GSH-PO) and testosterone action in rat ventral prostate, we have studied the immunocytochemical localization of GSH-PO in glandular epithelial cells of rat ventral prostate after chlormadinone acetate CMA) as antiandrogen. In the control rat ventral prostate, GSH-PO was predominantly observed in the glandular epithelial cells and intracellular localization of GSH-PO was exclusively observed in the cytoplasmic matrix near the rough endoplasmic reticulum and it was occasionally noted as small granular structure. In CMA-administered rats, the glandular epithelial cells of the ventral prostate were markedly atrophic. The intensity of GSH-PO staining in the glandular epithelial cells was markedly decreased. Immunoelectron microscopically, GSH-PO-positive granules were hardly seen in the atrophic glandular epithelial cells. These findings strongly suggest that loss of GSH-PO staining in the glandular epithelial cells of the rat ventral prostate treated with CMA a s antiandrogen is thought to be caused by inhibition of testosterone action, and that its staining pattern is useful for the effect of antiandrogens or antiprostatic agents on prostate.

MURC, a muscle-restricted coiled-coil protein, is involved in the regulation of skeletal myogenesis.

Skeletal myogenesis is a multistep process by which multinucleated mature muscle fibers are formed from undifferentiated, mononucleated myoblasts. However, the molecular mechanisms of skeletal myogenesis have not been fully elucidated. Here, we identified muscle-restricted coiled-coil (MURC) protein as a positive regulator of myogenesis. In skeletal muscle, MURC was localized to the cytoplasm with accumulation in the Z-disc of the sarcomere. In C2C12 myoblasts, MURC expression occurred coincidentally with myogenin expression and preceded sarcomeric myosin expression during differentiation into myotubes. RNA interference (RNAi)-mediated knockdown of MURC impaired differentiation in C2C12 myoblasts, which was accompanied by impaired myogenin expression and ERK activation. Overexpression of MURC in C2C12 myoblasts resulted in the promotion of differentiation with enhanced myogenin expression and ERK activation during differentiation. During injury-induced muscle regeneration, MURC expression increased, and a higher abundance of MURC was observed in immature myofibers compared with mature myofibers. In addition, ERK was activated in regenerating tissue, and ERK activation was detected in MURC-expressing immature myofibers. These findings suggest that MURC is involved in the skeletal myogenesis that results from modulation of myogenin expression and ERK activation. MURC may play pivotal roles in the molecular mechanisms of skeletal myogenic differentiation.

MURC, a muscle-restricted coiled-coil protein that modulates the Rho/ROCK pathway, induces cardiac dysfunction and conduction disturbance.

We identified a novel muscle-restricted putative coiled-coil protein, MURC, which is evolutionarily conserved from frog to human. MURC was localized to the cytoplasm with accumulation in the Z-line of the sarcomere in the murine adult heart. MURC mRNA expression in the heart increased during the developmental process from the embryonic stage to adulthood. In response to pressure overload, MURC mRNA expression increased in the hypertrophied heart. Using the yeast two-hybrid system, we identified the serum deprivation response (SDPR) protein, a phosphatidylserine-binding protein, as a MURC-binding protein. MURC induced activation of the RhoA/ROCK pathway, which modulated serum response factor-mediated atrial natriuretic peptide (ANP) expression and myofibrillar organization. SDPR augmented MURC-induced transactivation of the ANP promoter in cardiomyocytes, and RNA interference of SDPR attenuated the action of MURC on the ANP promoter. Transgenic mice expressing cardiac-specific MURC (Tg-MURC) exhibited cardiac contractile dysfunction and atrioventricular (AV) conduction disturbances with atrial chamber enlargement, reduced thickness of the ventricular wall, and interstitial fibrosis. Spontaneous episodes of atrial fibrillation and AV block were observed in Tg-MURC mice. These findings indicate that MURC modulates RhoA signaling and that MURC plays an important role in the development of cardiac dysfunction and conduction disturbance with increased vulnerability to atrial arrhythmias.

Osteopontin is a myosphere-derived secretory molecule that promotes angiogenic progenitor cell proliferation through the phosphoinositide 3-kinase/Akt pathway.

We have reported that skeletal myosphere-derived progenitor cells (MDPCs) can differentiate into vascular cells, and that MDPC transplantation into cardiomyopathic hearts improves cardiac function. However, the autocrine/paracrine molecules and underlying mechanisms responsible for MDPC growth have not yet been determined. To explore the molecules enhancing the proliferation of MDPCs, we performed serial analysis of gene expression and signal sequence trap methods using RNA isolated from MDPCs. We identified osteopontin (OPN), a secretory molecule, as one of most abundant molecules expressed in MDPCs. OPN provided a proliferative effect for MDPCs. MDPCs treated with OPN showed Akt activation, and inhibition of the phosphoinositide 3-kinase (PI3K)/Akt pathway repressed the proliferative effect of OPN. Furthermore, OPN-pretreated MDPCs maintained their differentiation potential into endothelial and vascular smooth muscle cells. These findings indicate an important role of OPN as an autocrine/paracrine molecule in regulating the proliferative growth of muscle-derived angiogenic progenitor cells via the PI3K/Akt pathway.

Papillary fibroelastoma of the aortic valve: evaluation with transesophageal echocardiography and magnetic resonance imaging.

A 74-year-old Japanese male was admitted to hospital with episodes of chest pain. Cross-sectional echocardiography showed a mobile mass adherent to the noncoronary cusp of the aortic valve. We employed transesophageal echocardiography and magnetic resonance imaging to evaluate the mass. Based on the findings, a papillary fibroelastoma of the aortic valve was suspected. To avoid systemic embolization, urgent surgery was performed. The histopathologic diagnosis was papillary fibroelastoma. When a tumor of the aortic valve exists, these examinations are useful in detecting and characterizing the tumor for optimal treatment.