Presentation/Session Information

Session Information

Session Title: Cell Fate, Differentiation and Morphogenesis Session Type: Parallel
Session Location: Northwest Auditorium Session Time: Sat, Jun 27 8:30AM - 11:30AM

Presentation Information

Program Number: 179 Presentation Time: 8:54AM - 9:06AM

Presentation Content

Centrosome-associated degradation limits SYS-1/β-catenin inheritance after asymmetric cell division.Setu Vora, Bryan Phillips. Biology, University of Iowa, Iowa City,

Cells of the C. elegans embryo navigate through invariant lineages in serial asymmetric cell divisions (ACDs), many of which are controlled by a modified Wnt/β-catenin signaling strategy.  Daughter cells derived from a Wnt-dependent ACD exhibit nuclear asymmetry of the transcriptional coactivator SYS-1/β-catenin, resulting in differential activation of Wnt-responsive target genes and distinct cell fates.  We investigated how dynamic localization of SYS-1 to mitotic centrosomes influenced SYS-1 inheritance and cell fate outcomes in daughter cells after division of the endomesodermal (EMS) blastomere.  Through yeast two-hybrid screening, we identified the centrosomal protein RSA-2 as a SYS-1 binding partner and showed that localization of SYS-1 to mitotic centrosomes was dependent on RSA-2.  Uncoupling SYS-1 from the centrosome by RSA-2 depletion increased SYS-1 inheritance after ACD and promoted Wnt-dependent cell fate.  Photobleaching experiments revealed that the entire fraction of centrosome-bound SYS-1 turns over rapidly during mitosis.  Interestingly, disruption of the proteasome led to an increased accumulation of SYS-1 at the centrosome but decreased the mobile fraction and turnover rate.  We conclude that centrosomal targeting of SYS-1 promotes its degradation during asymmetric cell division.  We propose a model whereby centrosome-associated SYS-1 degradation couples negative regulation with cell division timing to facilitate SYS-1 clearance from the mother cell at the time of asymmetric division.  These results suggest that proper spatial organization of signaling effectors such as SYS-1/β-catenin is necessary for permitting their efficient regulation during dynamic processes such as ACD.  .

Please note: Abstract shown here should NOT be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.

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