Coexisting adult polyglucosan body disease with frontotemporal lobar degeneration with transactivation response DNA-binding protein-43 (TDP-43)-positive neuronal inclusions

Almost one-third of the participants in a neuropsychological study signed the consent form below the given line. The relationship between a signature position on or below the line and participants’ cognitive function was investigated. Fifty drug-dependent individuals, 50 of their siblings, and 50 unrelated control participants completed a battery of neuropsychological tests using the Cambridge Neuropsychological Test Automated Battery (CANTAB). Individuals signing below, rather than on, the line performed more poorly on tests of visuospatial memory, but no differently on other cognitive tests. Signature positioning may be a soft sign for impairment of the mechanisms involved in visuospatial memory.     

Myc/his-TDP-43融合蛋白对tau外显子10可变剪接的影响

目的:构建带myc/his标签的pcDNA3.1/TDP-43及其截断体质粒,探讨myc/his-TDP-43融合蛋白对tau外显子10可变剪接的影响。方法:采用PCR法扩增TDP-43基因及其各截断体,将扩增产物和载体pcDNA3.1双酶切后回收,连接载体和目的片段,获得重组质粒。在HEK-293FT细胞中转染pcDNA3.1/TDP-43·myc·his及其截断体质粒,Western印迹法检测相关蛋白的表达。TDP-43或siTDP-43和tau迷你基因SI9/SI10共转,RT-PCR检测TDP-43对tau外显子10可变剪接的影响。结果:成功构建了pcDNA3.1/TDP-43·myc·his全长及各截断体质粒,并在HEK-293FT细胞中检测到其蛋白表达。Myc/his-TDP-43融合蛋白可呈剂量依赖性促进4R-tau的表达(P0.05或0.01)。结论:Myc/his-TDP-43融合蛋白可促进4R-tau的表达,携带myc/his标签不影响TDP-43对tau外显子10可变剪接的促进作用,为后续研究奠定了基础。     

缝隙连接与神经病理性痛的研究进展

缝隙连接是介导相邻细胞间物质转运、化学或电信号传递的专用跨膜通道,维持着细胞内环境的稳定。在神经系统中,缝隙连接不仅介导神经元和胶质细胞的胞间偶合,还参与病理条件下继发性损害。目前,研究证明缝隙连接在由神经系统损伤引起的神经病理性痛中发挥作用。对缝隙连接与神经病理性痛的关系进行研究有助于更深层次的了解神经病理性痛的发病机制,为治疗神经病理性痛提供新的研究方向。     

Skeletal muscle stem cells do not transdifferentiate into cardiomyocytes after cardiac grafting

Skeletal muscle cell-derived grafts in the heart may benefit myocardial performance after infarction. Several studies have suggested that skeletal muscle stem cells (satellite cells) from adult muscle undergo transdifferentiation into cardiomyocytes after grafting into the heart, but expression of cardiac markers in graft cells has not been rigorously confirmed. To determine the fate of satellite cell-derived grafts in the heart, adult rat satellite cells were tagged in vitro with bromodeoxyuridine (BrdU) and grafted into normal hearts of syngeneic rats. At 4 and 12 weeks the graft cells formed multinucleated, cross-striated myofibers that expressed fast skeletal myosin heavy chain (MHC), thus indicating a mature skeletal muscle phenotype. Double staining for the BrdU tag and cardiac-specific markers was employed to identify transdifferentiation. Aside from four questionable cells, none of the 11 grafts examined expressed alpha-MHC, cardiac troponin I, or atrial natriuretic peptide. At 4 weeks, grafts expressed beta -MHC, a hallmark of slow twitch myofibers. By 12 weeks, however, the myofibers had atrophied and downregulated beta-MHC. Grafts never expressed the intercalated disk proteins N-cadherin or connexin43, hence electromechanical coupling did not occur. In conclusion, satellite cells differentiate into mature skeletal muscle and do not express cardiac-specific genes after grafting into the heart. Thus, transdifferentiation into cardiomyocytes did not occur.     

Changes in Expression of Connexin 32, Bile Canaliculus-Like Structures,and Localization of Alkaline Phosphatase in Primary Cultures of Fetal Rat Hepatocytes

We devised an experimental design in primary cultures of fetal rat hepatocytes for studying hepatocyte differentiation over a short period. In the present study, hepatocytes were first cultured for 3 days in dexamethasone-supplemented medium and then for an additional 3 days in dexamethasone- or epidermal growth factor-supplemented medium. In hepatocytes cultured continuously in dexamethasone-supplemented medium, the expression of connexin 32 increased and bile canaliculus-like structures and localization of alkaline phosphatase in the plasma membrane around bile canaliculus-like structures were maintained. Few cells incorporated bromodeoxyuridine. On the other hand, in most of the hepatocytes cultured in epidermal growth factor-supplemented medium, the expression of connexin 32 was minimally recognized, bile canaliculus-like structures were shortened or eliminated, and alkaline phosphatase was localized as numerous fine spots throughout the cytoplasm. More than 20% of all hepatocytes incorporated bromodeoxyuridine.The present study suggests that in hepatocytes, there is a close relationship among connexin 32 expression, the maintenance of bile canaliculus-like structures, and the localization of alkaline phosphatase to the plasma membrane around the bile canaliculus-like structures, and this indicates that the present experimental model is useful for studying hepatocyte differentiation over a short period.