Dataset Information

Targeted polyubiquitylation of RASSF1C by the Mule and SCF?-TrCP ligases in response to DNA damage.

ABSTRACT: RASSF1A [Ras association (RalGDS/AF-6) domain family member 1A] and RASSF1C are two ubiquitously expressed isoforms of the RASSF1 gene. The promoter of RASSF1A is frequently hypermethylated, resulting in inactivation in various human cancers. RASSF1A is implicated in the regulation of apoptosis, microtubule stability and cell cycle arrest. However, little is known about the regulation and function of RASSF1C. In the present study we show that exogenously expressed RASSF1C is a very unstable protein that is highly polyubiquitylated and degraded via the proteasome. Furthermore, RASSF1C degradation is enhanced when cells are exposed to stress signals, such as UV irradiation. Mule, a HECT (homologous with E6-associated protein C-terminus) family E3 ligase, but not SCF?-TrCP [where SCF is Skp1 (S-phase kinase-associated protein 1)/cullin/F-box and ?-TrCP is ?-bransducin repeat-containing protein] or CUL4 (cullin 4)-DDB1 (damage-specific DNA-binding protein 1), is the E3 ligase for RASSF1C under normal conditions, whereas both Mule and SCF?-TrCP target RASSF1C degradation in response to UV irradiation. GSK3 (glycogen synthase kinase 3) phosphorylates RASSF1C to promote RASSF1C degradation subsequently, which is negatively regulated by the PI3K (phosphoinositide 3-kinase)/Akt pathway. Thus the present study reveals a novel regulation of RASSF1C and the potentially important role of RASSF1C in DNA damage responses.

SUBMITTER: Zhou X

PROVIDER: S-EPMC4610364 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Targeted polyubiquitylation of RASSF1C by the Mule and SCFβ-TrCP ligases in response to DNA damage.

Zhou Xin X Li Ting-Ting TT Feng Xu X Hsiang Esther E Xiong Yue Y Guan Kun-Liang KL Lei Qun-Ying QY

The Biochemical journal 20120101 1

RASSF1A [Ras association (RalGDS/AF-6) domain family member 1A] and RASSF1C are two ubiquitously expressed isoforms of the RASSF1 gene. The promoter of RASSF1A is frequently hypermethylated, resulting in inactivation in various human cancers. RASSF1A is implicated in the regulation of apoptosis, microtubule stability and cell cycle arrest. However, little is known about the regulation and function of RASSF1C. In the present study we show that exogenously expressed RASSF1C is a very unstable prot ...[more]

PMID: 21910689

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Project description:In eukaryotes many players in the DNA-damage response (DDR) catalyze protein sumoylation or ubiquitylation. Emphasis has been placed on how these modifications orchestrate the sequential recruitment of repair factors to sites of DNA damage or stalled replication forks. Here, we shed light on a pathway in which sumoylated factors are eliminated through the coupled action of Sumo-targeted ubiquitin ligases (STUbLs) and the ubiquitin-fusion degradation protein 1 (Ufd1). Ufd1 is a subunit of the Cdc48-Ufd1-Npl4 complex implicated in the sorting of ubiquitylated substrates for degradation by the proteasome. We find that in fission yeast, Ufd1 interacts physically and functionally with the Sumo-targeted ubiquitin ligase (STUbL) Rfp1, homologous to human RNF4, and with the Sumo E3 ligase Pli1, homologous to human PIAS1. Deleting a C-terminal domain of Ufd1 that mediates the interaction of Ufd1 with Rfp1, Pli1, and Sumo (ufd1?Ct(213-342) ) lead to an accumulation of high-molecular-weight Sumo conjugates and caused severe genomic instabilities. The spectrum of sensitivity of ufd1?Ct(213-342) cells to genotoxins, the epistatic relationships of ufd1?Ct(213-342) with mutations in DNA repair factors, and the localization of the repair factor Rad22 in ufd1?Ct(213-342) cells point to ufd1?Ct(213-342) cells accumulating aberrant structures during replication that require homologous recombination (HR) for their repair. We present evidence that HR is however often not successful in ufd1?Ct(213-342) cells and we identify Rad22 as one of the high-molecular-weight conjugates accumulating in the ufd1?Ct(213-342) mutant consistent with Rad22 being a STUbL/Ufd1 substrate. Suggesting a direct role of Ufd1 in the processing of Sumo-conjugates, Ufd1 formed nuclear foci colocalizing with Sumo during the DDR, and Sumo-conjugates accumulated in foci in the ufd1?Ct(213-342) mutant. Broader functional relationships between Ufd1 and STUbLs conceivably affect numerous cellular processes beyond the DDR.

Dataset Information

Targeted polyubiquitylation of RASSF1C by the Mule and SCF?-TrCP ligases in response to DNA damage.

Publications

Targeted polyubiquitylation of RASSF1C by the Mule and SCFβ-TrCP ligases in response to DNA damage.

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