线粒体转录因子A的研究进展

线粒体转录因子A是HMG蛋白家族中的成员,目前已知除了可以调控线粒体DNA的拷贝数和转录活性、参与细胞凋亡外,还可对人的寿命和疾病产生影响,如甲状腺功能减退性肌病和线粒体脑病等。近来研究还发现mtTFA也可在细胞核内发挥作用,提示核及线粒体基因表达调控的机制上存在偶联或协同作用。本文主要总结近年来关于线粒体转录因子A的研究进展,从其基因学定位和结构、蛋白质结构、基因表达调控及其主要功能做一概述,同时总结不同研究过程中提出的未知问题．并对进一步的研究方向做一展埋。     

Pentose cycle pathway in normal and tumoral islet cells

Relative to protein content, the activity of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase and the rate of glucose metabolism by the pentose cycle pathway in tumoral insulin-producing cells were similar to or higher than those found in normal rat islets. Hence, the decreased secretory response of tumoral cells to glucose is apparently not attributable to any major anomaly in glucose handling by the hexose monophosphate pathway.     

A platelet factor stimulating human normal glial cells.

Multiplication stimulating activities of human serum and fractions thereof have been determined as stimulation of [³H]thymidine incorporation of serum-deprived human glial cells. Serum prepared from cell-free plasma had a considerably lower activity than serum prepared from whole blood. The major part of the growth-promoting activity of serum could be ascribed to a platelet factor, released during the coagulation process. The factor was trypsin-labile and heat-stable. A partial purification of the factor was achieved by ion exchange chromatography on CM-Sephadex at neutral pH. The purified material was 600–700 times as active as normal human serum on a protein basis.     

Differentiation of normal and tumoral human keratinocytes cultured on dermis: Reconstruction of either normal or tumoral architecture

Summary Normal human keratinocytes isolated from skin and squamous carcinoma cells established from a human tumor (TR146 cell line) both exhibit limited morphologic differentiation when they are grown on conventional plastic dishes. However, when they are seeded on human de-epidermized dermis and cultured at the air-liquid interface, they are able to reform an epithelium having the morphology of the tissue of origin (i.e. skin or squamous carcinoma). The distribution in such reconstructed tissues of differentiation markers such as bullous pemphigoid antigen, 67K keratin, involucrin, membrane-bound transglutaminase, and filaggrin was very similar to their distribution in normal skin and squamous carcinoma specimens, respectively. The degree of differentiation is for both cell types extremely sensitive to culture conditions such as retinoic acid concentration, emersion of the cultures, etc. These results show that subcultured normal or tumoral keratinocytes are able to recover their specific morphogenetic potential when cultured in an environment close to their in vivo situation.