訊息蛋白SH2B1β增進PC12細胞之神經修復能力

The Adaptor Protein SH2B1β Enhances Neuronal Regeneration in PC12 Cells

周瑀涵(Yu-Han Chou)

指導教授 ： 陳令儀

國立清華大學/生命科學院/分子醫學研究所/碩士(2009年)

摘要

在神經系統發育的過程，神經細胞為了存活而相互競爭有限的營養因子。神經細胞若無法得到足夠的營養因子，就會開始走向細胞凋亡。雖然細胞凋亡在神經系統發育是必然的過程，但是成熟的神經細胞不正常的死亡而使結構及功能日益失去就會造成神經退化的疾病，如阿茲海默症與帕金森氏症。SH2B1β是一種訊息接合蛋白，參與許多生長因子的訊息傳遞路徑，像是神經生長因子(nerve growth factor, NGF)及纖維母細胞生長因子一(fibroblast growth factor 1, FGF1)下游的訊息傳遞。NGF可誘導大鼠腎上腺髓質嗜鉻細胞瘤細胞株 (rat pheochromocytoma cell line, 以下簡稱PC12 細胞)的神經分化，進而分化成為類交感神經細胞。先前的研究發現，SH2B1β可以增加PC12細胞由NGF及FGF1所誘導的神經分化，此外，我們最近的研究發現，SH2B1β還可以減少由氧化壓力所造成的細胞死亡，而氧化壓力也被認為是造成神經退化疾病原因之一。因此，我們推測SH2B1β對於神經退化及神經修復可能扮演一些重要的角色。我們發現SH2B1β可以減少由缺乏NGF所造成的神經退化，也可以增加軸突受傷之後的修復，因此我們更進一步探討SH2B1β如何增進神經細胞受傷之後的修復。我們發現SH2B1β可以透過許多機制來增加神經修復。一個被認為是神經修復標定的蛋白質--- GAP-43，在大量表現SH2B1β的細胞中高度表現，因此SH2B1β可能可以調控GAP-43表現而增加PC12細胞的修復能力。另外，STAT3、NCAM-L1以及N-cad的表現量隨著修復時間的增加，都有逐漸下降的趨勢，並且它們的表現量在大量表現SH2B1β的細胞中都較少。NCAM-L1及N-cadherin這些蛋白質可使細胞移動的速度增加，可以更快速的到傷口區域來促進修復。

關鍵字

SH2B1β ； 神經修復

並列摘要

During development of vertebrate nervous system, neurons compete for limited target-derived trophic factors for survival. Insufficient neurotrophic support renders cells undergoing programmed cell death. Although cell death is a normal process during neuronal development, abnormal cell death of matured neurons and progressive loss of structure or function results in neurodegeneration such as Alzheimer’s disease and Parkinson’s disease. The adaptor protein SH2B1β is a signaling molecule that participates in various signaling pathway including nerve growth factor (NGF) and fibroblast growth factor (FGF) signaling. SH2B1β also enhances NGF- as well as FGF1-induced neurite outgrowth in PC12 cell, a well-established neuronal model that can be differentiated into sympathetic-like neurons upon NGF challenge. Moreover, our recent results suggest that SH2B1β could reduce oxidative stress-induced cell death. Oxidative stress has been linked to the neuronal cell death, which is associated with various neurodegenerative conditions. These results lead us to hypothesize that SH2B1β may play a role in neuronal degeneration and/or regeneration. In this study, I have shown that SH2B1β reduces neuronal degeneration during NGF deprivation and enhances regeneration after nerve injury. In addition, SH2B1β regulates the pro-inflammatory cytokines-induced signaling. To understand the mechanisms by which SH2B1β exerts its effect, we use wound healing assay as an injury model to investigate how SH2B1 enhances neuronal regeneration. I have found that SH2B1-overexpressing cells express higher level of growth-associated protein-43 (GAP-43), that may promote regeneration. In addition, down-regulation of STAT3, NCAM-L1, and N-cadherin might affect cell motility which leads cells migrate to the wounded area to promote regeneration. Taken together, SH2B1β may utilize multiple mechanisms to promote regeneration.

並列關鍵字

SH2B1β ； neuronal regeneration

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