An integrated radiation hybrid map of bovine chromosome 18 that refines a critical region associated with multiple ocular defects in cattle

Ocular forkhead transcription factors: seeing eye to eye

Forkhead transcription factors comprise a large family of proteins with diverse functions during development. Recently, there has been accumulating evidence that several members of this family of proteins play an important role in the development of the vertebrate retina. Here, we summarize the cumulative data which demonstrates the integral role that forkhead factors play in cell cycle control of retinal precursors, as well as in cell fate determination, during retinal development. The expression patterns for 14 retinal expressed forkhead transcription factors are presented with an emphasis on comparing the expression profiles across species. The functional data regarding forkhead gene products expressed within the retina are discussed. As presented, these data suggest that forkhead gene products contribute to the complex regulation of proliferation and differentiation of retinal precursors during vertebrate eye development.

Reversal of RNA polymerase II ubiquitylation by the ubiquitin protease Ubp3

The final outcome of protein polyubiquitylation is often proteasome-mediated proteolysis, meaning that "proofreading" of ubiquitylation by ubiquitin proteases (UBPs) is crucial. Transcriptional arrest can trigger ubiquitin-mediated proteolysis of RNA polymerase II (RNAPII) so a UBP reversing RNAPII ubiquitylation might be expected. Here, we show that Ubp3 deubiquitylates RNAPII in yeast. Genetic characterization of ubp3 cells is consistent with a role in elongation, and Ubp3 can be purified with RNAPII, Def1, and the elongation factors Spt5 and TFIIF. This Ubp3 complex deubiquitylates both mono- and polyubiquitylated RNAPII in vitro, and ubp3 cells have elevated levels of ubiquitylated RNAPII in vivo. Moreover, RNAPII is degraded faster in a ubp3 mutant after UV irradiation. Problems posed by damage-arrested RNAPII are thought to be resolved either by removing the damage or degrading the polymerase. In agreement with this, cells with compromised DNA repair are better equipped to survive UV damage when UPB3 is deleted.