Targeted dephosphorylation of TFEB promotes its nuclear translocation

Reversible phosphorylation of the transcription factor EB (TFEB) coordinates cellular responses to metabolic and other stresses. During nutrient replete and stressor-free conditions, phosphorylated TFEB is primarily localised to the cytoplasm. Stressor-mediated reduction of TFEB phosphorylation promotes its nuclear translocation and context-dependent transcriptional activity. In this study, we explored targeted dephosphorylation of TFEB as an approach to activate TFEB in the absence of nutrient deprivation or other cellular stress. Through an induction of proximity between TFEB and several phosphatases using the AdPhosphatase system, we demonstrate targeted dephosphorylation of TFEB in cells. Furthermore, by developing a heterobifunctional molecule BDPIC (bromoTAG-dTAG proximity-inducing chimera), we demonstrate targeted dephosphorylation of TFEB-dTAG through induced proximity to bromoTAG-PPP2CA. Targeted dephosphorylation of TFEB-dTAG by bromoTAG-PPP2CA with BDPIC at the endogenous levels is sufficient to induce nuclear translocation and some transcriptional activity of TFEB.

转录因子EB（TFEB）的可逆磷酸化可协调细胞对代谢应激及其他应激的应答。在营养充足且无应激的条件下，磷酸化TFEB主要定位于细胞质。应激介导的TFEB磷酸化水平降低可促进其核转位与情境依赖性转录活性。本研究探索了以TFEB靶向去磷酸化为策略，在无需营养剥夺或其他细胞应激的情况下激活TFEB。通过AdPhosphatase系统诱导TFEB与多种磷酸酶间的邻近效应，我们在细胞中实现了TFEB的靶向去磷酸化。此外，通过开发双功能杂合分子BDPIC（bromoTAG-dTAG邻近诱导嵌合体），我们证实可通过诱导TFEB-dTAG与bromoTAG-PPP2CA的邻近效应，实现TFEB-dTAG的靶向去磷酸化。在内源性水平下，借助BDPIC使bromoTAG-PPP2CA对TFEB-dTAG进行靶向去磷酸化，足以诱导TFEB发生核转位并产生部分转录活性。