Ribonuclease H activity in developing rat brain

A ribonucleolytic enzyme (RNase H) which degrades the RNA strand of a RNA-DNA double stranded hybrid has been extracted from rat brain and characterized. RNase H activity in the cerebella increased up to around 6th day after birth and then decreased in adult rat cerebella, just as DNA polymerase and DNA ligase. The RNase H activity in non-cerebellar part decreased gradually toward adult after birth. On the other hand, RNase activity did not change during development of brain. The activity of total RNase is high at newborn, and decreased to 12th day after birth. These results suggest that RNase H is implicated in DNA replication in rat brain.     

Investigation of the formation of triple helices between (pro-pro-gly)n's of different degrees of polymerization using gel filtration

The properties of triple-helix formation of (Pro-Pro-Gly)_n were studied. The probability of hybridization between the polytripeptides (Pro-Pro-Gly)_n, of different degrees of polymerization was investigated by gel filtrations of mixed solutions of them. Using samples selectively labeled with radioactivity, the elution pattern was detected by uv absorption and liquid scintillation counting. The hybridization was found only when the difference of polymerization is small. The amount of heterohelices (triple helices of the polypeptide chains with different degrees of polymerization) measured by integrated intensity of elution pattern was comparable to the theoretical value of Suezaki and Go. Concentration dependence of the helix–coil transition temperature of (Pro-Pro-Gly)_n was also measured by the use of optical rotation and discussed with the theoretically expected values.     

The effect of aging on cell-cycle kinetics and X-ray-induced chromosome aberrations in cultured lymphocytes from patients with Down syndrome.

To evaluate the effects of aging on cytogenetic characteristics of lymphocytes from Down syndrome (DS), cell-cycle kinetics after PHA stimulation and chromosome-type aberration frequencies after X-ray exposure were investigated in vitro in the lymphocytes derived from 4 (or 3 for X-ray treatment) age groups of DS patients and age-matched controls. The results clearly showed higher mitotic and proliferation index levels in younger groups compared to older groups at the various culture intervals, whether the lymphocytes were from the DS patients or controls. The age-related changes of the proliferation index were mainly attributed to a delayed response to PHA as age increased. The changes of PHA responses seemed to be particularly marked during adolescence. Nonetheless, no significant differences were observed between the DS patients and age-matched controls for each age group. In all age groups, frequencies of both chromosome-type exchanges and deletions were elevated in the DS patients by about 1.3 times in comparison with the controls. The magnitude of radiosensitivity, however, seemed to decrease slightly in the 40-49-year group. To our knowledge, the present study is the first report in the literature to deal with the effect of aging on the greater radiosensitivity of DS lymphocytes.     

Hypoxia-Inducible Factors Activate CD133 Promoter through ETS Family Transcription Factors

CD133 is a cellular surface protein that has been reported to be a cancer stem cell marker, and thus it is considered to be a potential target for cancer treatment. However, the mechanism regulating CD133 expression is not yet understood. In this study, we analyzed the activity of five putative promoters (P1–P5) of CD133 in human embryonic kidney (HEK) 293 cells and colon cancer cell line WiDr, and found that the activity of promoters, particularly of P5, is elevated by overexpression of hypoxia-inducible factors (HIF-1α and HIF-2α). Deletion and mutation analysis identified one of the two E-twenty six (ETS) binding sites (EBSs) in the P5 region as being essential for its promoter activity induced by HIF-1α and HIF-2α. In addition, a chromatin imunoprecipitation assay demonstrated that HIF-1α and HIF-2α bind to the proximal P5 promoter at the EBSs. The immunoprecipitation assay showed that HIF-1α physically interacts with Elk1; however, HIF-2α did not bind to Elk1 or ETS1. Furthermore, knockdown of both HIF-1α and HIF-2α resulted in a reduction of CD133 expression in WiDr. Taken together, our results revealed that HIF-1α and HIF-2α activate CD133 promoter through ETS proteins.     

Facile synthesis of fused 1,2,4-triazolo[1,5-c]pyrimidine derivatives as human adenosine A3 receptor ligands

A facile synthetic method for fused triazolopyrimidine derivatives having high affinity and selectivity for human adenosine A(3) receptors is reported. The fused triazolopyrimidine derivatives were easily prepared by one-pot reaction using acylhydrazines and imidates prepared from amine derivatives bearing cyano group and orthoesters in situ. This synthetic method was useful in finding new tricyclic adenosine A(3) receptor antagonists and also in diversifying the substituents at two positions on the fused triazolopyrimidine ring.     

Structure-activity relationships of adenosine A3 receptor ligands: new potential therapy for the treatment of glaucoma

Structure-activity relationships (SAR) of fused 1,2,4-triazolo[1,5-c ]pyrimidine were performed. Various substituents were introduced into the heterocyclic ring to improve the potency of adenosine A(3) receptor binding affinity and A(3)-selectivity against other subtypes. Potent and selective A(3) receptor antagonists were identified and were evaluated in a monkey model of intraocular pressure by eye-drop administration. As a result, compound 1c (OT-7999) was found to significantly decrease intraocular pressure in the animal model.     

Physiological roles of prolactin-releasing peptide

Prolactin-releasing peptide (PrRP) was first isolated from bovine hypothalamus as an orphan G-protein-coupled receptor using the strategy of reverse pharmacology. The initial studies showed that PrRP was a potent and specific prolactin-releasing factor. Morphological and physiological studies, however, indicated that PrRP may play a wide range of roles in neuroendocrinology other than prolactin release, i.e., metabolic homeostasis, stress responses, cardiovascular regulation, gonadotropin secretion, GH secretion and sleep regulation. This review will provide the current knowledge of PrRP, especially its roles in energy metabolism and stress responses.     

Matrix metalloproteinase-7 degrades all insulin-like growth factor binding proteins and facilitates insulin-like growth factor bioavailability

Proteolytic modification of insulin-like growth factor binding proteins (IGFBPs) plays an important physiological role in regulating insulin-like growth factor (IGF) bioavailability. Recently, we demonstrated that matrix metalloproteinase-7 (MMP-7)/Matrilysin produced by various cancer cells catalyzes the proteolysis of IGFBP-3 in vitro and regulates IGF bioavailability, resulting in an anti-apoptotic effect against anchorage-independent culture. In the present study, we investigated whether MMP-7 contributes to proteolysis of the other five IGFBPs, IGFBP-1, IGFBP-2, IGFBP-4, IGFBP-5, and IGFBP-6, and whether this results in phosphorylation of the IGF type 1 receptor (IGF-1R). MMP-7 cleaved all six IGFBPs, resulting in IGF-mediated IGF-1R phosphorylation, which was inhibited by EDTA treatment. These results suggest that MMP-7 derived from cancer cells can regulate IGF bioavailability in the microenvironment surrounding the tumor, where various kinds of IGF/IGFBP complexes are found, thereby favoring cancer cell growth and survival during the processes of invasion and metastasis.     

Characterization of human stellate cell activation-associated protein and its expression in human liver

This study cloned cDNA of human homologue (hSTAP) of rat stellate cell activation-associated protein (rSTAP). hSTAP gene is on chromosome 17q and is composed of four exons. Various types of cells including hepatic stellate cells expressed hSTAP mRNA. Recombinant hSTAP was a heme protein with the activity of peroxidase. hSTAP can be used as a marker of quiescent stellate cells in human liver.