Localization of a novel RNA-binding protein, SKIV2L2, to the nucleus in the round spermatids of mice.

In our previous study (Kawashima et al., Biol Reprod 2009; 80: 1293-1304), we suggested that the first cycle of spermatogenesis recovered from busulfan-induced temporary arrest was a good model system to analyze the proteins expressed at the specific stages of spermatogenesis in the mouse, and this has been confirmed in the present paper. Namely, six-week-old mice were injected with busulfan at 20 mg/kg body weight. The germ cells except for the undifferentiated spermatogonia disappeared by 32 days after injection. The surviving spermatogonia started to proliferate, and spermatogenesis was entirely recovered about 77 days after injection. By proteome analysis of the busulfan-treated testis during the process of recovery of spermatogenesis, we identified a protein that was expected to be expressed in the spermatogenic cells as Superkiller viralicidic activity-2-like-2 (SKIV2L2). Skiv2l2 mRNA was found in the kidney, epididymis and heart as well as the testis. In the testis, Skiv2l2 mRNA was shown to be highly expressed in the spermatocytes at stages I to VI. On the other hand, SKIV2L2 protein was found to be predominantly localized in the nuclei of round spermatids. In accordance with the fact that SKIV2L2 belongs to the Ski2 family within the superfamily 2 of RNA helicases, it has been shown that SKIV2L2 has both the RNA-binding and ATPase activities.

CABS1 is a novel calcium-binding protein specifically expressed in elongate spermatids of mice.

Single intraperitoneal injection of busulfan at 20 mg/kg body weight to mature male mice induced the deletion of the spermatogenic cells, followed by the restoration of the spermatogenesis by the surviving undifferentiated spermatogonia. The changes of the protein contents in testis during these processes were analyzed by two-dimensional gel electrophoresis in order to identify the proteins expressed at the specific stages of spermatogenesis. An acidic protein that disappeared and recovered in the same time course as spermatids after the busulfan treatment was identified as CABS1 by mass spectrometry. It was found that CABS1 was specifically expressed in the elongate spermatids at steps 13 to 16 in stages I to VIII of the seminiferous epithelium cycle of the mouse, and then it localized to the principal piece of flagellum of the mature sperm in the cauda epididymis. We have found for the first time that CABS1 is a calcium-binding protein that binds calcium during the maturation in the epididymis.

A case of genital folliculosebaceous cystic hamartoma with an unique aggregated manifestation.

Folliculosebaceous cystic hamartoma (FCH) is a recently recognized cutaneous hamartoma composed of follicular, sebaceous and mesenchymal components, and usually occurring on the head and neck. We describe herein a case of FCH with an unique aggregated manifestation in a genital lesion. The patient was a 40-year-old woman with a genital lesion composed of a pedunculated nodule, a dome-shaped nodule and a subcutaneous nodule, measuring 5 cm in the greatest dimension. The largest, pedunculated nodule was histologically composed of an infundibulo-cystic structure with follicular, sebaceous and mesenchymal elements accompanied by cystic structures of various sizes lined by stratified squamous epithelium and follicular germinative cells suggesting follicular cysts. The dome-shaped nodule consisted of anastomosing strands of epithelial cells with follicular components. The subcutaneous nodule had two components, an infundibulo-cystic structure and a cyst lined by squamous epithelium. In our case, the unusual clinical feature of large and multiple nodules was due to the presence of several prominent hamartomatous cystic structures with FCH. This is the third case of giant FCH. The clinical presentation and location of giant FCH is unusual.