SUMOylation of RepoMan during late telophase regulates dephosphorylation of lamin A.

Dephosphorylation of lamin A, which triggers nuclear lamina reconstitution, is crucial for the completion of mitosis. However, the specific phosphatase and regulatory mechanism that allow timely lamin A dephosphorylation remain unclear. Here, we report that RepoMan (also known as CDCA2), a regulatory subunit of protein phosphatase 1γ (PP1γ) is transiently modified with SUMO-2 at K762 during late telophase.

Transcription Factor hDREF Is a Novel SUMO E3 Ligase of Mi2α.

The human transcription factor DNA replication-related element-binding factor (hDREF) is essential for the transcription of a number of housekeeping genes. The mechanisms underlying constitutively active transcription by hDREF were unclear. Here, we provide evidence that hDREF possesses small ubiquitin-like modifier (SUMO) ligase activity and can specifically SUMOylate Mi2α, an ATP-dependent DNA helicase in the nucleosome remodeling and deacetylation complex.

Lamin A reassembly at the end of mitosis is regulated by its SUMO-interacting motif.

Modification of proteins with small ubiquitin-related modifier (SUMO; SUMOylation) is involved in the regulation of various biological processes. Recent studies have demonstrated that noncovalent associations between SUMOylated proteins and co-operative proteins containing SUMO-interacting motifs (SIMs) are important for the spatiotemporal organization of many protein complexes. In this study, we demonstrate that interactions between lamin A, a major component of the nuclear lamina, and SUMO isoforms are dependent on one of the four SIMs (SIM3) resided in lamin A polypeptide in vitro.

Long-term expression of the lamin A mutant associated with dilated cardiomyopathy induces senescence.

Mutation of the lamin A gene (LMNA) causes a diverse range of diseases referred to as laminopathies. Because most laminopathies have a dominant inheritance pattern and progress gradually, cultured cells stably expressing mutant lamin A at the same level as endogenous wild-type cells are required for chronological analysis. In this study, we showed that an expression system involving a lentiviral vector that carries the human metallothionein gene basal promoter ensures stable and basal-level expression of proteins and is thus suitable for investigating the properties of lamin A mutants.