Identification of SENP5 target proteins by endogenous SUMO2/3 IP-MS

ABSTRACT: Ribosome biogenesis is a complex and energy demanding process requiring tight coordination with cell growth and proliferation. Impairment of ribosome biogenesis activates a well-defined cell-cycle checkpoint that primarily relies on the activation of p53 signaling. However, there is mounting evidence that p53-independent signaling networks connect impaired ribosome biogenesis to cell cycle-checkpoints. So far, however, these pathways have remained largely enigmatic. By characterizing the nucleolar SUMO isopeptidase SENP3 and SENP5 we found that both isopeptidases control the SUMOylation state of specific ribosome biogenesis factors and regulate the 60S and 40S ribosome maturation pathways. Accordingly, inactivation of SENP3 and SENP5 induces a canonical p53-mediated G1/S arrest. Intriguingly, however, we discovered that inactivation of SENP3 or SENP5 drastically and specifically downregulates the expression of the key-cell cycle regulator CDK6 in a p53-independent process. Accordingly, depletion of SENP3 or SENP5 impairs G1/S transition and cell proliferation in both p53-proficient and p53-deficient cells. Strikingly, we further revealed that impaired ribosome maturation induced by depletion of a panel of ribosome biogenesis factors or by chemical inhibition of RNA polymerase I, generally triggers loss of CDK6 independent of the cellular p53 status. Altogether our data unveil a long-sought p53-independent checkpoint of impaired ribosome biogenesis. Since CDK6 represents a dependency in a subset of cancer entities, such as AML and lymphoma, we propose that this checkpoint can serve as an actionable drug target in tumor therapy.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Hela Cell

SUBMITTER: Stefan Müller  

LAB HEAD: Stefan Müller

PROVIDER: PXD037796 | Pride | 2023-10-28

REPOSITORIES: Pride