探讨CDK12及CDK13在神经分支发育过程中的功能(精)
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探討CDK12及CDK13在神經分支發育過程中的功能
Characterization of CDK12 and CDK13 functions in neurite outgrowth
林冠廷
Guan-Ting Lin
神經科學研究所
關鍵詞:
神經分支;發育;
Keyword:
CDK12;CDK13;neurite outgrowth;
摘要:
CDK12及CDK13是兩種需依賴Cyclin而活化的新穎蛋白。
此二種蛋白質已知可藉由與L型Cyclin相互聯
結進而參與RNA選擇性剪接的調控。
過去也已發現CDK12可以藉由磷酸化RNA聚合酶的C端來促
進基因的轉錄。
另外也已知CDK12及CDK13會表現在正在發育時期的神經系統,因此認為CDK12及CDK
13對於神經系統的發育有相當的重要性。
本篇文章中,我們探討CDK12及CDK13兩種蛋白對於神經
分化過程的影響,因此我們在P19細胞株中將CDK12或CDK13 過度表現,或利用RNAi技術抑制此兩種
蛋白的表現。
經過神經分化後,我們發現如果抑制了CDK12或CDK13的表現,神經突起的生長也
會跟著被抑制。
因此推測CDK12及CDK13是促使神經突起生長的基本因子。
接著我們利用基因微
陣列晶片技術、反轉錄聚合酶連鎖反應以及西方墨點法去觀察哪些基因的表現會受到CDK1
2表現的影響。
我們發現Nkx2-9及Cdk5均會被CDK12調控。
Nkx2-9是Nk2轉錄因子的成員,此蛋白家族
擁有Homeodomain,並且已發現可以特化及引導發育時期後腦的spinal accessory neuron的生長。
而CDK5
也已知在小鼠腦皮層細胞中為神經突起生長的基本因子。
我們利用RNAi技術抑制CDK5的表現,
發現神經突起的生長確實也受到抑制。
要更進一步探討在神經突起生長過程中CDK5是否位於CD
K12及CDK13的下游,我們在抑制CDK12及CDK13表現的同時,大量表現CDK5,發現神經突起的生長有
部分被回復的現象。
因此可以證明,CDK12及CDK13可能可以部分地調控CDK5的表現,進而促使並
保持神經突起的生長。
Abstract:
CDK12 and CDK13 are two newly identified cyclin-dependent kinases involved in the alternative splicing regulation through interacting with L-type cyclins. It was also shown that CDK12 phosphorylates the
C-terminal domain of RNA polymerase II and thus may regulate transcription. Expression of CDK12 and CDK13 are in the developing nervous system, suggesting the two proteins might play an important role in the neural development. Here, we examined effects of CDK12 and CDK13 on neuronal differentiation. When depleting the CDK12 or CDK13 in mouse embryonal carcinoma cells (P19 cells) by small-interfering RNAs (siRNAs) or microRNAs (miRNAs), the neurite outgrowth was significantly decreased, suggesting CDK12 and CDK13 have an essential role in maintaining the neurite outgrowth of differentiated P19 cells. To identify how CDK12 and CDK13 affect the neurite outgrowth, microarray analysis, semi-quantitative PCR assay and Western blotting analysis were performed. Two genes that were down-regulated after knockdown of CDK12 and CDK13 are Nkx2-9 and Cdk5. Nkx2-9 is a member of Nk-2 transcription factors which contains a homeodomain, specifies and guides the spinal accessory neurons in the hindbrain during development. CDK5 is essential for neurite outgrowth in rat embryonic cortical neurons. To verify CDK5 does involve in the neurite outgrowth, CDK5 was knocked down by RNA interference. The neurite outgrowth showed decreased after inhibiting CDK5 expression. In the subsequent P19 cell differentiation assay, it was found that CDK5 overexpression could partially rescue the decreased neurite outgrowth while depleting expression of CDK12 or CDK13. To sum up, CDK12 and CDK13 may modulate the neurite outgrowth in P19 cells, in part, due to their effects on CDK5 expression.。