Egydio de Carvalho, CarlosVan Bostelen, IvoGu, YanjieChu, Diana S.Cheeseman, Iain M.Tzur, Yonatan BNadarajan, SaravanapriahColaiacovo, Monica2013-03-292012Tzur, Yonatan B., Carlos Egydio de Carvalho, Saravanapriah Nadarajan, Ivo Van Bostelen, Yanjie Gu, Diana S. Chu, Iain M. Cheeseman, and Monica P. Colaiácovo. 2012. LAB-1 targets PP1 and restricts Aurora B Kinase upon entrance into meiosis to promote sister chromatid cohesion. PLoS Biology 10(8): e1001378.1544-91731545-7885http://nrs.harvard.edu/urn-3:HUL.InstRepos:10474257Successful execution of the meiotic program depends on the timely establishment and removal of sister chromatid cohesion. LAB-1 has been proposed to act in the latter by preventing the premature removal of the meiosis-specific cohesin REC-8 at metaphase I in C. elegans, yet the mechanism and scope of LAB-1 function remained unknown. Here we identify an unexpected earlier role for LAB-1 in promoting the establishment of sister chromatid cohesion in prophase I. LAB-1 and REC-8 are both required for the chromosomal association of the cohesin complex subunit SMC-3. Depletion of lab-1 results in partial loss of sister chromatid cohesion in rec-8 and coh-4 coh-3 mutants and further enhanced chromatid dissociation in worms where all three kleisins are mutated. Moreover, lab-1 depletion results in increased Aurora B kinase (AIR-2) signals in early prophase I nuclei, coupled with a parallel decrease in signals for the PP1 homolog, GSP-2. Finally, LAB-1 directly interacts with GSP-1 and GSP-2. We propose that LAB-1 targets the PP1 homologs to the chromatin at the onset of meiosis I, thereby antagonizing AIR-2 and cooperating with the cohesin complex to promote sister chromatid association and normal progression of the meiotic program.en-USBiologyJournal Article2013-03-2910.1371/journal.pbio.1001378