| Islet cell transplantation has been a new therapy for the treatment of patients with diabetes mellitus. However, it is still a problem in getting enough and integrity islet-like cell clusters(ICCs) from human embryo pancreat. Deficiency of human pancreatic islet cells cultured in vitro partly due to the high rate of cell apoptosis, and whether using pancreatie islet stem cells or transgenic islet cells of Langhens to get enough ICCs, it was needed to better understanding its development, differentiation and apopotosis.The apoptotic process appears to be regulated by proteins that also function in proliferation and differentiation. The transforming growth factor beta (TGF- β )regulates fundamental physiological processes, such as cell growth, differentiation and apoptosis, in almost all cell types.TGF- β could inhibit cell proliferation, induced cell differentiation and apoptosis for its up-regulation of cyclin dependent kinase inhibitors (CDKIs) p21/Waf-l, p27/Kip1 and p15/INK4a, which resulted in the block of CDK function, Rb hypophosphorylation and the transcription factor E2F inactivation and driving cells into S phase.As constitutively activated Ras and Raf are known to be able to induce expression of the cyclin-dependent kinase inhibitors p16 INK4A and p21 wAFI/CIP1 through mechanism -s involving p53. It is possible that this pro-apoptotic effect of Ras is tied in with cell-cycle regulation and is part of a protective response of cells against excessive activation of the Ras-MAP kinase pathway. Strong activation of the MAP kinase pathway in Swiss 3T3 fibroblasts results in the apoptosis of cells in S phase but the arrest of cells in other parts of the cell cycle. It is unlikely that these responses of the cell to strong constitutive activation of the MAP kinase pathway have any relevance to normal Ras mediated mitogen signalling, which is relatively transient and weak.The c-fos, an immediate-early gene, codes for a nucle99ar protein that dimerizes with Jun family proteins to form the transcription factor complex activator protein 1 (AP-1). c-fos, is transiently expressed during growth factor deprivation-induced apoptosis. sufficient evidences show that c-fos should be included as a primary modulator of apoptoticcell death.In this study, on the base of isolated and cultured human embryo pancreatic islet cell cultured, semi-quantitative RT-PCR assays were used to detect P21ras mRNA expression of different growth periods of islet cells and fibroblast cells. The expressions of c-fos and TGF-β protein were examined utilizing immunohistochemistry. The quantities of apoptosis relative factors in different growth period were compared, so were compared the different quantities of apoptosis relative factors in islet and fibroblast cells in the same growth period. The correlation between apoptosis and apoptosis relative factors was valued. Here, the main research results are as follows:1. The method used show satisfactory result in purifing the pancreatic islet cells. And the cultured islet cells grow and function well, proved by PCM and insulin releasing detection.2. Islet cells were arrested at G1 phase, and the rate of apoptosis of islet cells was higher than that of fibroblast cells.3. P21ras expression of fibroblast in exponential growth period was stronger than in incubation period and retention period. However, no significant diffierence was found in the expression of P2Iras in cultured pancreatic islet cells.4. Islet cells had stronger TGF- β 1 expression in retention period than in incubation period and exponential growth period. Nevertheless, the expression of fibroblast in different periods was weaker than that of islet cells.5. The expression of c-fos in retention period of both could be detected, while not in incubation period and exponential growth period.These results conform, 1. The method, proved successfully in isolating and culturing islet cells could be used in further study. 2. P21ras may stimulate fibroblast cells development probably due to the...
|
PDF Full Text Request