PT  - JOURNAL ARTICLE
AU  - Kian-Yong Lee
AU  - Rebecca A. Green
AU  - Edgar Gutierrez
AU  - J. Sebastian Gomez-Cavazos
AU  - Irina Kolotuev
AU  - Shaohe Wang
AU  - Arshad Desai
AU  - Alex Groisman
AU  - Karen Oegema
TI  - CYK-4 functions independently of its centralspindlin partner ZEN-4 to cellularize oocytes in germline syncytia
AID  - 10.1101/196279
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 196279
4099  - http://biorxiv.org/content/early/2017/09/29/196279.short
4100  - http://biorxiv.org/content/early/2017/09/29/196279.full
AB  - Throughout metazoans, germ cells undergo incomplete cytokinesis to form syncytia connected by intercellular bridges. Formation of gametes ultimately requires bridge closure. Here, we investigate the contribution of the conserved bridge component centralspindlin to oocyte production in C. elegans. Centralspindlin is composed of the Rho family GTPase-activating protein (GAP) CYK-4/MgcRacGAP and the microtubule motor ZEN-4/kinesin-6, which are both essential for cytokinesis. In contrast, we show that oocyte production by the syncytial germline requires CYK-4 but not ZEN-4. Longitudinal imaging after conditional CYK-4 inactivation revealed a role in oocyte cellularization, rather than in generation of syncytial compartments. CYK-4’s lipid-binding C1 domain and the GTPase-binding interface of its GAP domain were individually important for oocyte cellularization and for targeting CYK-4 to bridges, where it contributes to enrichment of active RhoA. These results identify a C1-GAP module in CYK-4 that recruits it to bridges in the germline and directs their closure to produce oocytes.IMPACT STATEMENT The CYK-4 subunit of centralspindlin, a broadly conserved component of intercellular bridges across metazoa, is required for the cytokinesis-like closure of intercellular bridges that cellularizes oocytes to separate them from germline syncytia.MAJOR SUBJECT AREAS Cell Biology, Developmental Biology & Stem Cells