Scleraxis modulates bone morphogenetic protein 4 (BMP4)-Smad1 protein-smooth muscle α-actin (SMA) signal transduction in diabetic nephropathy

Activation of mesangial cells (MCs), which is characterized by induction of smooth muscle α-actin (SMA) expression, contributes to a key event in various renal diseases; however, the mechanisms controlling MC differentiation are still largely undefined. Activated Smad1 induced SMA in a dose-dependent manner in MCs. As a direct regulating molecule for SMA, we identified and characterized scleraxis (Scx) as a new phenotype modulator in advanced glycation end product (AGE)-exposed MCs. Scx physically associated with E12 and bound the E-box in the promoter of SMA and negatively regulated the AGE-induced SMA expression. Scx induced expression and secretion of bone morphogenetic protein 4 (BMP4), thereby controlling the Smad1 activation in AGE-treated MCs. In diabetic mice, Scx was concomitantly expressed with SMA in the glomeruli. Inhibitor of differentiation 1 (Id1) was further induced by extended treatment with AGE, thereby dislodging Scx from the SMA promoter. These data suggest that Scx and Id1 are involved in the BMP4-Smad1-SMA signal transduction pathway besides the TGFβ1-Smad1-SMA signaling pathway and modulate phenotypic changes in MCs in diabetic nephropathy.     

Differential Expression of the 5-HT3A and 5-HT3B Receptor in Differentiated NG108-15 Cells

Previous work from this laboratory has shown that the serotonin (5-HT) induced response is significantly augmented in differentiated NG108-15 (NG) cells treated with dibutyryl cAMP (Bt(2)cAMP) due to qualitative and quantitative changes in the expression of the 5-HT(3) receptor as demonstrated by specific [(3)H] LY-278584 (a selective 5HT(3) receptor antagonist) binding. In this study, we investigated whether there is any change in the relative expression of the 5-HT(3A) and 5-HT(3B) subunits in NG cells differentiated following Bt(2)cAMP treatment cells. The major findings of this study were that the relative amount of 5-HT(3B) subunit mRNA in Bt(2)cAMP-treated NG cells 5 days following Bt(2)cAMP-treatment was greater than that in the untreated cells. In contrast, the relative expression of the 5-HT(3B) subunit protein in the Bt(2)cAMP-treated NG cells was much less than in the untreated cells, but the relative expression of the 5-HT(3A) subunit in the Bt(2)cAMP-treated NG cells was similar to the untreated cells. Therefore, no relationship between mRNA and protein expression for 5-HT(3A) and 5-HT(3B) subunits in Bt(2)cAMP treated and untreated NG cells were observed. It was also found that fluorescent intensity for the 5-HT(3B) subunit in the cell body of the Bt(2)cAMP treated and untreated NG cells gradually decreased from the day 1-5 after Bt(2)cAMP treatment. However, in specific areas such as the varicosity and nerve endings of the Bt(2)cAMP treated cells, staining intensity for the 5-HT(3B) subunits was stronger than in the untreated cells at the all time points, peaking at day 5 post-treatment. These results suggest that the augmented response induced by 5-HT acting via 5-HT(3) receptors in differentiated NG cells may be due to changes in the relative amount of the 5-HT(3B) subunit, particularly the ratio and distribution of the 5-HT(3A) to (3B) subunits.     

A case of pancreatic neuroendocrine tumor in a patient with neurofibromatosis-1

ABSTRACT: Patients with neurofibromatosis-1 (NF-1) sometime develops neuroendocrine tumors (NET). Although these NETs usually occur in the duodenum or peri-ampullary region, they occasionally grow in the pancreas (PNET). A 62-year-old man with NF-1 had mild liver dysfunction and was admitted to our hospital for further examination. An abdominal contrast enhanced computed tomography scan demonstrated a 30 mm tumor in the head of the pancreas. The scan showed showed an invasion of the tumor into the duodenum, and biopsy under an endoscopic ultrasonography indicated that the tumor was a NET. A subtotal stomach-preserving pancreaticoduodenectomy was performed. Macroscopically, the pancreatic tumor was white and elastic hard. Microscopically, tumor cells were composed of ribbons, cords, and solid nests with acinus-like structure. The tumor was diagnosed as NET G2 according to WHO classification (2010). The product of NF-1 gene, i.e., neurofibromin, was weakly positive in the tumor cells, suggesting that the tumor was induced by a mutation in the NF-1 gene. This is the seventh case of PNET arising in NF-1 patients worldwide.     

Structural and functional properties of CiNTH, an endonuclease III homologue of the ascidian Ciona intestinalis: critical role of N-terminal region

Oxidatively damaged bases in DNA can cause cell death, mutation and/or cancer induction. To overcome such deleterious effects of DNA base oxidation, cells are equipped with base excision repair (BER) initiated by DNA glycosylases. Endonuclease III (Nth), a major DNA glycosylase, mainly excises oxidatively damaged pyrimidines from DNA. The aims of this study were to obtain an overview of the repair mechanism of oxidatively damaged bases and to elucidate the function of BER in maintaining genome stability during embryogenesis and development. In this study, we used the ascidian Ciona intestinalis because at every developmental stage it is possible to observe the phenotype of individuals with DNA damage or mutations. Sequence alignment analysis revealed that the amino acid sequence of Ciona intestinalis Nth homologue (CiNTH) had high homology with those of Escherichia coli, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Caenorhabditis elegans and human Nth homologues. It was evident that two domains, the Helix-hairpin-Helix and 4Fe-4S cluster domains that are critical regions for the Nth activity, are well conserved in CiNTH. CiNTH efficiently complemented the sensitivity of E. coli nth nei mutant to H(2)O(2). CiNTH was bifunctional, with DNA glycosylase and AP lyase activities. It removed thymine glycol, 5-formyluracil and 8-oxoguanine paired with G from DNA via a β-elimination reaction. Interestingly, the N-terminal 44 amino acids were essential for the DNA glycosylase activity of CiNTH.     

Dorsal Root Ganglia-Specific Expression of the β-Galactoside α1,2-Fucosyltransferase Genes in Rabbits

Abstract: The neurons of dorsal root ganglia (DRG) mediate several sensation modalities. The carbohydrate antigens on DRG neurons differ with the sensation modalities that subsets of neurons convey. Despite the important roles of gangliosides and glycoproteins in neuronal differentiation and neuritogenesis of the mammalian nervous system, little is known about the mechanisms underlying the regulation of glycosylation. We previously demonstrated the expression of H-blood type antigens (Fucα1, 2Galβ) on rabbit DRG neurons of small diameter and dramatic changes in H antigens during the perinatal period. To investigate the possible biological roles and regulatory mechanisms of H antigens, we recently cloned three types of rabbit α1,2-fucosyltransferase gene that catalyze the biosynthesis of H antigens. Here, we analyze the expression of these genes, RFT-I, II, and III, in rabbit DRG. The H-type α1,2-fucosyltransferase gene, RFT-I, was expressed in DRG in late embryos to adult rabbits, as detected on northern blotting. The other two secretor-type α1,2-fucosyltransferase genes, RFT-II and III, were observed to be expressed in late embryonic DRG on RTPCR analysis but were not detectable on northern blotting. The expression of the H-type α1,2-fucosyltransferase gene was analyzed by in situ hybridization and was found to be abundant in small-diameter DRG neurons. These results indicate that the H-type α1,2-fucosyltransferase gene plays a major role in the regulation of the H antigen expression in DRG during the perinatal period.     

Three new asymmetric trans-amine(azole)dichloridoplatinum complexes that overcome cisplatin resistance and their reactions with 5′-GMP

Three new asymmetric platinum(II) complexes comprising an isopropylamine ligand trans to an azole ligand were synthesized and fully characterized by ¹H NMR, ¹⁹⁵Pt NMR, IR and elemental analysis. In addition the X-ray crystal structure of all three complexes was determined. The reaction kinetics of the complexes with DNA model base guanosine-5′-monophosphate (GMP) was studied, revealing reaction kinetics comparable to cisplatin. To gain insight in the complexes as potential antitumor agents, cytotoxicity assays were performed on a variety of human tumor cell lines. These assays showed the complexes all to possess cytotoxicity profiles comparable to cisplatin. Furthermore, the complexes largely retain their activity in a human ovarian carcinoma cell line resistant to cisplatin, A2780R, compared to the cisplatin sensitive parent cell line A2780. These results are of fundamental importance, illustrating how platinum complexes of trans geometry can show improved activity compared to cisplatin in both cisplatin sensitive and cisplatin resistant cell lines.