The SUMO-conjugating enzyme Ubc9 is an essential enzyme in the SUMO (small ubiquitin-related modifier) protein modification system. Although sumoylation, covalent modification of cellular proteins by SUMO, is considered to regulate various cellular processes, and many substrates for sumoylation have been identified recently, the regulation of Ubc9 expression has not been examined in detail. We analyzed the expression of Ubc9 during rat brain development at the mRNA and protein levels. Northern and Western blot analyses revealed that expression of Ubc9 and SUMO-1 was developmentally regulated, while that of the ubiquitin-conjugating enzyme UbcH7 did not change so dramatically. In situ hybridization analysis revealed that the expression of Ubc9 was high in neuronal stem cells and moderate in differentiated neurons at embryonic stages. In the adult brain, moderate expression was observed in subsets of neurons, such as the dentate granular neurons and pyramidal neurons in the hippocampal formation and the large pyramidal neurons in the cerebral cortex. These results suggest that the Ubc9-SUMO system might participate in the proliferation and differentiation of neuronal cells in the developing brain and in neuronal plasticity in the adult brain.
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We demonstrated the development of antral ulcers induced in rats by alendronate and investigated the pathogenic factors involved in this model. Animals fasted for 18 h were given alendronate p.o., and then re-fed normally and killed on various days up to 7 days later. Alendronate caused non-hemorrhagic damage in both the corpus and antrum of fasted rats, but after refeeding for 3 days the lesions in the corpus healed completely, while those in the antrum developed into large ulcers with increased vascular permeability. The development of antral ulcers was accompanied by an increase in MPO activity and lipid peroxidation as well as a decrease in SOD activity and GSH content in the mucosa. Histologically, the damage did not penetrate the muscularis mucosa, yet severe edema and neutrophil infiltration were observed in the submucosa. Neither omeprazole nor indomethacin had any effect, while allopurinol and SOD reduced the severity of these ulcers. Rebamipide dose-dependently suppressed the ulcerogenic response to alendronate, with a concomitant reversal of the increased vascular permeability, MPO activity and lipid peroxidation as well as the reduced SOD activity and GSH content. These results suggest that alendronate did not cause gross damage in the stomach of fasted rats, yet produced large ulcers in the antrum with severe edema after refeeding. The pathogenesis of these ulcers may be explained by impairment of the mucosal anti-oxidative system and does not involve acid/peptic digestion and deficiency of prostaglandins. Rebamipide prevents the antral ulcers, probably due to its anti-oxidative as well as anti-inflammatory actions.
Transplantation of bone marrow stromal cells (BMSCs) for spinal cord injury (SCI) has been shown to improve functional outcome. BMSCs can be easily obtained from bone marrow aspirate and have fewer problems in the clinical application for human SCI from the ethical and legal points of view. Recently, we produced cells with neural stem and/or progenitor cell property and neural regeneration supporting capacity from human bone marrow stromal cells (human bone marrow stromal cell-derived neuroregenerative cells: hBMSC-NRs). The aim of the present study was to clarify the effectiveness of transplantation of hBMSC-NRs to injured spinal cord of severe combined immunodeficiency (NOD/SCID) mice. Neurite outgrowth assay of PC-12 cells was performed. One week after a T9-level contusion SCI, hBMSCs or hBMSC-NRs were transplanted into the spinal cord. After the transplantation, functional and histological examinations were performed. Conditioned media of hBMSC-NRs significantly promoted the neurite outgrowth of PC-12 cells in vitro. Transplanted hBMSC-NRs survived in the injured spinal cord 8 weeks after SCI. Immunohistochemistry revealed that the density of serotonin-positive fibers of the transplanted group was significantly higher than that of the control group at the epicenter and caudal segment to the injured site. The recovery of hind limb function of the hBMSC-NRs group was significantly better than that of the control group. In conclusion, hBMSC-NRs can be one of the realistic candidates for cell transplantation therapy for human SCI.
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