CK2β促进Pink1/Parkin介导的Miro1降解

CK2β Promotes Pink1/Parkin-mediated Miro1 Degradation

帕金森氏病相关蛋白PTEN-induced putative kinase 1(PINK1)在细胞内有两种亚型,分别是定位于线粒体表面的全长PINK1(PINK1FL)和定位于细胞质的PINK1-cyto。PINK1FL能在功能下降的线粒体表面积累,协同另一帕金森病相关蛋白PARKIN降解线粒体转运因子MIROL1,但目前对PINK1-cyto的功能却了解得极少。为了探讨PINK1-cyto在细胞质中的生理学功能,我们在HEK293细胞中通过细胞转染瞬时表达不同蛋白,并利用免疫共沉淀的方法探讨蛋白质间的相互作用。实验结果表明,PINK1-cyto在Casein KinaseⅡ调控亚基CK2β的帮助下,可以协同PARKIN降解MIRO1,并且CK2β的这一功能不依赖于Casein KinaseⅡ的催化亚基CK2α。同时,免疫共沉淀分析表明CK2β可以促进PINK1-cyto与MIROL1的结合。这说明,除了与CK2α结合外,CK2β也可以与PINK1-cyto结合形成具有生理活力的激酶复合体。

PTEN-induced putative kinase 1 （PINK1）, a Parkinson＇ s disease （PD）-related protein, has two isoforms, the mitochondria-localized full-length isoform PINK1FL and the cytoplasm-localized short isoform PINKl-cyto. Studies have suggested that PINK1FL can selectively accumulate at the surface of damaged mitochondria and cooper ate with another Parkinson＇s Disease-related protein PARKIN to trigger the degradation of MIRO1, a mitochondria trafficking regulator. The functions of PINKl-cyto are, however, not yet clear. To investigate the functions of PINK l-cyto, we expressed different proteins in cultured HEK293 cells by transfecting it with different plasmids, and detected the protein levels by Western blot after expressing for 24 h. We found that in cultured HEK293 cells, PINKl-cyto could also cooperate with PARKIN degrade MIRO1 in the presence of CK2β, and the regulatory subunit of Casein Kinase Ⅱ. Interestingly, this function of CK213 was not dependent on CK2α, the catalytic subunit of Casein Kinase Ⅱ. We also found that CK213 could promote the direct interaction between PINKl-cyto and MIRO1 by immu- nocoprecipitation analysis. This result suggested that in addition to CK2a, CK213 could also form a kinase complex with PINKl-cyto with important physiological functions.