Preliminary Study Of Signaling Molecules Mediating Bilirubin-Induced Apoptosis In Human Neuroblastoma SH-SY5Y Cells

Neonatal hyperbilirubinemia is one of the risk factors leading to hearing loss of neonates. Auditory brainstem responses of neonates with severe hyperbilirubinemia might indicate that there were pathological changes in the auditory central nucleus; Research showed morphological changes in the cochlear and nucleus of trapezoid body in Gunn rat pups which is the genetic animal model of hyperbilirubinemia; Hyperbilirubinemia also is the most frequent pathogeny of auditory neuropathy. Consequently, It is very significant to study the mechanism that bilirubin damage central nerve system.Apoptosis is a response of cell to the dramatic changes during the surrounding environment. Diverse extracellular stimuli including irradiation, ultraviolet light, heat shock, high osmotic, proinflammatory cytikines such as interleukin-1 and tumor necrosis factor, oxidative stress, nitric oxide, hypoxia, transforming growth factor- 3 can trigger apoptosis. Such stimuli are sensed by receptors at the cell surface, and transmitted to cytosolic and nuclear targets by the activation of intracellular signal transduction pathways. Diverse signal pathways including protein kinase A, protein kinase C, mitogen-activated protein kinase(MAPK) mediate the apoptotic response, in particular, the family of P38MAPK and c-jun N-terminal kinase both belonging to the MAPK superfamily play a important roles.We use the bilirubin directly acting on human neuroblastoma cell line SH-SY5Y cells to study the mechanism by which bilirubin damage neurons, especially the signaling transduction pathway. Utilizing the techniques of molecular biology and cell biology we observe that bilirubin induce apoptosis in SH-SY5Y cells, and its effect on the mitochondrial membrane potential; we establish a cell line SH-SY5Ybcl-2 with overexpression of bcl-2 protein, and observe the effect of bcl-2 on bilirubin-induced apoptosis and disruption of mitochondrail membrane potential of SH-SY5Y cells. Applying the P38MAPK specific inhibitor SB203580 we observe the role of P38 in the signal transduction of biliribin-induced apoptosis in SH-SY5Y cells. To further prove this we set up a cell line SH-SY5Yantip38 with low expression of P38MAPK...