Nature. 2013 Mar 14;495(7440):255-9.
USP33 regulates centrosome biogenesis via deubiquitination of the centriolar protein CP110.
Centrosome duplication is controlled in part by CP110, a centriolar protein that positively regulates centriole duplication while restricting centriole elongation and ciliogenesis. CP110 levels are tightly controlled, partly through ubiquitination by the ubiquitin ligase complex SCF(cyclin F) during G2 and M phases of the cell cycle. Here, using human cells, we report a new mechanism for the regulation of centrosome duplication that requires USP33, a deubiquitinating enzyme that is able to regulate CP110 levels. We find that USP33 activity antagonizes SCF(cyclin F)-mediated ubiquitination and promotes the generation of supernumerary centriolar foci. In contrast, ablation of USP33 destabilizes CP110 and thereby inhibits centrosome amplification. To our knowledge, we have identified the first centriolar deubiquitinating enzyme whose expression regulates centrosome homeostasis by countering cyclin-F-mediated destruction of a key substrate.
Blum R, Vethantham V, Bowman C, Rudnicki M, and Dynlacht BD (2012)
Genome-wide identification of enhancers in skeletal muscle: the role of MyoD1
Genes and Development 26: 2763-2779.
To identify the compendium of distal regulatory elements that govern myogenic differentiation, we generated chromatin state maps based on histone modifications and recruitment of factors that typify enhancers in myoblasts and myotubes. We found a striking concordance between the locations of these newly defined enhancers, MyoD1-binding events, and noncoding RNA transcripts. These enhancers recruit several sequence-specific transcription factors in a spatially constrained manner around MyoD1-binding sites. Remarkably, MyoD1-null myoblasts show a wholesale loss of recruitment of these factors as well as diminished monomethylation of H3K4 (H3K4me1) and acetylation of H3K27 (H3K27ac) and reduced recruitment of Set7, an H3K4 monomethylase. Surprisingly, we found that H3K4me1, but not H3K27ac, could be restored by re-expression of MyoD1 in MyoD1−/− myoblasts, although re-expression of this factor in MyoD1-null myotubes restored both histone modifications. Our studies identified a role for MyoD1 in condition-specific enhancer assembly through recruitment of transcription factors and histone-modifying enzymes that shape muscle differentiation.