Hiroshi Kubota

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Spermatogonial stem cells (SSCs) self-renew and produce large numbers of committed progenitors that are destined to differentiate into spermatozoa throughout life. However, the growth factors essential for self-renewal of SSCs remain unclear. In this study, a serum-free culture system and a transplantation assay for SSCs were used to identify exogenous(More)
The expanding number of members in the various human heat shock protein (HSP) families and the inconsistencies in their nomenclature have often led to confusion. Here, we propose new guidelines for the nomenclature of the human HSP families, HSPH (HSP110), HSPC (HSP90), HSPA (HSP70), DNAJ (HSP40), and HSPB (small HSP) as well as for the human chaperonin(More)
The pluripotential cell-specific gene Nanog encodes a homeodomain-bearing transcription factor required for maintaining the undifferentiated state of stem cells. However, the molecular mechanisms that regulate Nanog gene expression are largely unknown. To address this important issue, we used luciferase assays to monitor the relative activities of deletion(More)
Cell fate determination between self-renewal or differentiation of spermatogonial stem cells (SSCs) in the testis is precisely regulated to maintain normal spermatogenesis. However, the mechanisms underlying the process remain elusive. To address the problem, we developed a model SSC culture system, first, by establishing techniques to obtain enriched(More)
The distribution of histidine decarboxylase-like immunoreactivity (HDCI) in the rat central nervous system was studied by the indirect immunofluorescence technique. HDCI cell bodies were concentrated in the posterior hypothalamic area, such as in the tuberal magnocellular nucleus, caudal magnocellular nucleus, posterior hypothalamic nucleus and lateral(More)
Spermatogonial stem cells (SSCs) are responsible for maintaining spermatogenesis throughout life in the male by continuous production of daughter cells that differentiate into spermatozoa. However, no unique phenotypic markers to identify SSCs have been described. In this study, the SSC surface phenotype was characterized by using flow cytometric cell(More)
We studied the clinical features and laboratory findings in 213 patients with HTLV-I-associated myelopathy/tropical spastic paraparesis as diagnosed in Kagoshima University Hospital. Some aspects of clinical features in HTLV-I-associated myelopathy/tropical spastic paraparesis were characterized by mode of HTLV-I transmission and age of onset. The patients(More)
Arginine rich, mutated in early stage of tumors (ARMET) was first identified as a human gene highly mutated in a variety of cancers. However, little is known about the characteristics of the ARMET protein and its expression. We identified ARMET as a gene upregulated by endoplasmic reticulum (ER) stress. Here, we show that the mouse homologue of ARMET is an(More)
Polyglutamine (polyQ)-expansion proteins cause neurodegenerative disorders including Huntington's disease, Kennedy's disease and various ataxias. The cytotoxicity of these proteins is associated with the formation of aggregates or other conformationally toxic species. Here, we show that the cytosolic chaperonin CCT (also known as TRiC) can alter the course(More)
Using data obtained in national surveys of human T-lymphotropic virus type I (HTLV-I)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) conducted in Japan in 1987 and 1988, we estimated the yearly and lifetime risk that HAM/TSP will develop in an HTLV-I-infected person. "Definite" HAM/TSP was defined as slowly progressive myelopathy with(More)