Abstract
DNA damage can induce autophagy; however, the underlying mechanism remains largely unknown. Here we report that DNA damage leads to autophagy through ATR/Chk1/RhoB-mediated lysosomal recruitment of TSC complex and subsequent mTORC1 inhibition. DNA damage caused by ultraviolet light (UV) or alkylating agent methyl methanesulphonate (MMS) results in phosphorylation of small GTPase RhoB by Chk1. Phosphorylation of RhoB enhances its interaction with the TSC2, and promotes its sumoylation by PIAS1, which is required for RhoB/TSC complex to translocate to lysosomes. As a result, mTORC1 is inhibited, and autophagy is activated. Knockout of RhoB severely attenuates lysosomal translocation of TSC complex and the DNA damage-induced autophagy. Reintroducing wild-type but not sumoylation-resistant RhoB into RhoB−/− cells restores the onset of autophagy. Hence, our study identifies a molecular mechanism for translocation of TSC complex to lysosomes in response to DNA damage, which depends on ATR/Chk1-mediated RhoB phosphorylation and sumoylation.
Highlights
DNA damage can induce autophagy; the underlying mechanism remains largely unknown
As we have shown that ultraviolet light (UV) or methyl methanesulphonate (MMS)-induced DNA damage response (DDR) is mainly through Chk[1] signaling pathway (Supplementary Fig. 2b), we investigated whether ATR/Chk[1] signaling is involved in regulating the UV or MMS-triggered autophagy
We found that colocalization of endogenous RhoB and TSC2 was dramatically increased after UV or MMS treatment (Fig. 7c; Supplementary Fig. 7g)
Summary
DNA damage can induce autophagy; the underlying mechanism remains largely unknown. We report that DNA damage leads to autophagy through ATR/Chk1/RhoBmediated lysosomal recruitment of TSC complex and subsequent mTORC1 inhibition. Our study identifies a molecular mechanism for translocation of TSC complex to lysosomes in response to DNA damage, which depends on ATR/Chk1-mediated RhoB phosphorylation and sumoylation. We found that RhoB is phosphorylated by Chk[1] after DNA damage, which promotes its binding to SUMO E3 ligase PIAS1 and subsequent sumoylation. This phosphorylation enhances the binding of RhoB to TSC complex. The sumoylated phospho-RhoB functions as a carrier protein to translocate TSC complex to lysosomes, initiating autophagy by inhibiting mTORC1 activity
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