酪氨酸去磷酸酶N9在細胞自噬扮演角色之研究

The role of Protein Tyrosine Phosphatase N9 in autophagy

李逸唐(Yi-Tang Lee)

指導教授 ： 陳光超

國立臺灣大學/生命科學院/生化科學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.10143

摘要

PTPN9 (非穿膜型蛋白質酪氨酸去磷酸酶九號) 是一個典型的酪氨酸去磷酸酶. 它可以拮抗酪氨酸磷酸酶的作用, 進而將酪氨酸上的磷酸根去除掉. PTPN9 已被報導過有多種功能, 例如抑制EGFR/Her2或是VEGFR的訊息傳遞網, 以及參與在胞泌泡囊的融合. 在這篇論文中, 我們研究了PTPN9在細胞自噬中的作用機制. 我們發現在人類子宮頸癌細胞HeLa中大量表現PTPN9會造成饑餓狀態下細胞自噬的通量加速, 並且很有可能是透過促進自噬小體和溶酶體的融合. 另一方面我們也觀察到在饑餓狀態下, PTPN9會與Atg16和Atg9在同樣的位置. 有趣的是PTPN9在一般狀態下是存在於初級內體以及在循環內體的細胞質面, 正是Atg16和Atg9所存在的胞器. 由上述的觀察我們假定PTPN9在饑餓狀態下會經由Atg16+Atg9+的小泡被招募到吞噬胞, 並促進自噬小體的形成. 我們也觀察到PTPN9會與細胞自噬專屬的SNARE作用. 此外, PTPN9大量表現可以促進去除細胞自噬專屬SNARE的酪氨酸磷酸化.

關鍵字

非穿膜型蛋白質酪氨酸去磷酸?九號 ； 非穿膜型蛋白質酪氨酸去磷酸?meg2 ； 細胞自噬 ； 自噬溶?體 ； 細胞自噬專屬SNAREs

並列摘要

PTPN9, also known as PTPmeg2, is a classical non-transmembrane protein tyrosine phosphatase that antagonizes the tyrosine phosphorylation exerted by protein tyrosine kinase. PTPN9 has been reported to have multiple functions, including EGFR/Her2 signal inactivation, VEGFR signal inactivation, and secretary vesicle fusion facilitation. In this study, we investigate the role of PTPN9 in autophagy. We discovered that overexpression of PTPN9 in HeLa cells accelerates the autophagic flux upon starvation, which is very likely through promoting the autolysosome fusion. Immunostaining assays showed that PTPN9 colocalizes with Atg16 and Atg9 upon starvation. Interestingly, under fed condition, PTPN9 localizes at early and recycling endosome, which is where Atg16 and Atg9 normally resides. These findings lead us to hypothesize that PTPN9 might be recruited to the phagophore via Atg16+Atg9+ vesicle, and facilitates autophagy. We also discovered that PTPN9 colocalizes and interacts with components of the autophagic SNARE complex. Furthermore, the tyrosine phosphorylation of autophagic SNARE can be reduced upon PTPN9 overexpression.

並列關鍵字

PTPN9 ； PTPmeg2 ； autophagy ； autolysosome fusion ； autophagic SNAREs

參考文獻

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