探討 IRSp53 和 SH2B1beta 在形成絲狀偽足中的角色

Role of IRSp53 and SH2B1beta in filopodium formation

洪紹景

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(2013年)

https://doi.org/10.6843/NTHU.2013.00297

摘要

絲狀偽足 (Filopodia) 是一細長且富含肌動蛋白的細胞膜突起結構。絲狀偽足在許多生理過程中扮演重要的角色，包括病原偵測，細胞遷移，傷口癒合以及生長發育。在神經發育過程中，樹突及樹突小刺形成之前，必須先形成絲狀偽足。Insulin receptor substrate protein of 53 kDa (IRSp53) 在先前已被證實會參與調控絲狀偽足的形成。我們初步的結果指出，大量表現一個訊息連接蛋白 SH2B1β 能夠增進海馬迴神經細胞的生長。因此，本研究假設 IRSp53 和 SH2B1β 可能會共同調控細胞骨架的重組，進而促成絲狀偽足的形成。本研究中顯示，在人類胚胎腎細胞株 (293T cells) 中，大量表現 IRSp53 或 SH2B1β 皆能誘導絲狀偽足的形成。此外， SH2B1β 會與 IRSp53 結合，共同增進絲狀偽足的形成以及造成絲狀偽足的分支。另外，本研究也進一步發現，增進絲狀偽足的形成需要 IRSp53 的 IMD 和 SH3 domain 以及 SH2B1β 的 N 端 proline-rich domain，而其中造成絲狀偽足增加的機制為 IRSp53 會吸引SH2B1β 到細胞膜上。最後，本研究也證實， IRSp53 和 SH2B1β 會共同作用，增進海馬迴神經細胞的生長與分枝。總結來說，本研究首先發現 SH2B1β 會透過 IRSp53 複合體，來促進絲狀偽足的形成以及神經軸的生長。

關鍵字

絲狀偽足

並列摘要

Filopodia are thin, actin-enriched structure of membrane protrusions. Filopodia play instrumental roles in pathogen detection, cell migration, wound healing, and during development. During neurogenesis, filopodium formation precedes the formation of dendrites and spines. The insulin receptor substrate protein of 53 kDa (IRSp53) has been shown to regulate the formation of filopodia. Our preliminary results suggest that overexpressing an adaptor protein SH2B1β enhances neurite outgrowth of hippocampal neurons. Thus, I hypothesize that IRSp53 and SH2B1β may act together to regulate actin cytoskeleton remodeling and thus filopodium formation. In this thesis, I show that overexpression of either IRSp53 or SH2B1β induces the filopodium formation of 293T cells. In addition, SH2B1β interacts with IRSp53 to enhance filopodium formation and highly branched filopodia. Furthermore, IMD and SH3 domains of IRSp53 as well as N-terminal proline-rich domains of SH2B1β are required for the enhancement of filopodium formation. One mechanism for this enhancement of filopodia is that IRSp53 recruits SH2B1β to the plasma membrane. Finally, I demonstrate that IRSp53 and SH2B1β synergistically enhance neurite branching of hippocampal neurons. Taken together, this study provides novel findings that SH2B1β interacts with IRSp53-containing complexes to promote filopodium formation and thus neurite outgrowth.

並列關鍵字

IRSp53 ； SH2B1 ； filopodium

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