PP2A-dependent TFEB activation is blocked by PIKfyve-induced mTORC1 activity.
PP2A-dependent TFEB activation is blocked by PIKfyve-induced mTORC1 activity.
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DOI：
10.1091/mbc.e21-06-0309
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发表时间：
2022-03-01
影响因子：
3.3
通讯作者：
Weisman, Lois S.
中科院分区：
文献类型：
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作者：
Hasegawa, Junya;Tokuda, Emi;Yao, Yao;Sasaki, Takehiko;Inoki, Ken;Weisman, Lois S.
转录因子EB （TFEB）是自噬和溶酶体功能所需基因的主要调节因子。TFEB的核定位被雷帕霉素复合物1 （mTORC1）依赖的TFEB在多个位点磷酸化的机制靶标阻断，包括Ser-211。在这里，我们发现抑制PIKfyve（在核内体和溶酶体上产生磷脂酰肌醇3,5-二磷酸）会导致Ser-211磷酸化的丧失和伴随的TFEB核定位。我们发现，虽然mTORC1对S6K1以及其他主要mTORC1底物的活性没有受损，但PIKfyve抑制特异性地阻碍了TFEB与mTORC1的相互作用。这表明mTORC1对TFEB的活性由于mTORC1对TFEB的访问丢失而被选择性抑制。此外，我们发现在抑制PIKfyve的过程中，TFEB的激活依赖于蛋白磷酸酶2A （PP2A）而不是钙调神经磷酸酶/PPP3去磷酸化TFEB Ser-211的能力。因此，当PIKfyve被抑制时，PP2A在控制Ser-S211的TFEB磷酸化方面优于mTORC1。这些发现表明，mTORC1和PP2A分别通过Ser-211的磷酸化和去磷酸化对TFEB具有相反的作用，并且PIKfyve通过促进mTORC1依赖性的TFEB磷酸化来抑制TFEB活性。
Transcriptional factor EB (TFEB) is a master regulator of genes required for autophagy and lysosomal function. The nuclear localization of TFEB is blocked by the mechanistic target of rapamycin complex 1 (mTORC1)-dependent phosphorylation of TFEB at multiple sites including Ser-211. Here we show that inhibition of PIKfyve, which produces phosphatidylinositol 3,5-bisphosphate on endosomes and lysosomes, causes a loss of Ser-211 phosphorylation and concomitant nuclear localization of TFEB. We found that while mTORC1 activity toward S6K1, as well as other major mTORC1 substrates, is not impaired, PIKfyve inhibition specifically impedes the interaction of TFEB with mTORC1. This suggests that mTORC1 activity on TFEB is selectively inhibited due to loss of mTORC1 access to TFEB. In addition, we found that TFEB activation during inhibition of PIKfyve relies on the ability of protein phosphatase 2A (PP2A) but not calcineurin/PPP3 to dephosphorylate TFEB Ser-211. Thus when PIKfyve is inhibited, PP2A is dominant over mTORC1 for control of TFEB phosphorylation at Ser-S211. Together these findings suggest that mTORC1 and PP2A have opposing roles on TFEB via phosphorylation and dephosphorylation of Ser-211, respectively, and further that PIKfyve inhibits TFEB activity by facilitating mTORC1-dependent phosphorylation of TFEB.