Biology subjects

Rocancourt, M.

Publications and source records attributed to Rocancourt, M..

2 recordsLinked to original sources

bioRxiv2023

MiniBAR/KIAA0355 is a dual Rac and Rab effector required for ciliogenesis

Cilia protrude from the cell surface and play critical roles in in-tracellular signaling, environmental sensing and development. Actin-dependent contractility and intracellular trafficking are both required for ciliogenesis, but little is known about how these processes are coordinated. Here, we identified a Rac1-and Rab35-binding protein with a truncated BAR domain that we named MiniBAR (aka KIAA0355/GARRE) which plays a key role in ciliogenesis. MiniBAR colocalizes with Rac1 and Rab35 at the plasma membrane and on intracellular vesicles traffick-ing to the ciliary base and exhibits remarkable fast pulses at the ciliary membrane. MiniBAR depletion leads to short cilia resulting from abnormal Rac-GTP/Rho-GTP levels, increased acto-myosin-II-dependent contractility together with defective trafficking of IFT88 and ARL13B into cilia. MiniBAR-depleted zebrafish embryos display dysfunctional short cilia and hall-marks of ciliopathies including left-right asymmetry defects. Thus, MiniBAR is a unique dual Rac and Rab effector that con-trols both actin cytoskeleton and membrane trafficking for cili-ogenesis.

cell biology↗

bioRxiv2020

The Flemmingsome reveals an ESCRT-to-membrane coupling required for completion of cytokinesis

Cytokinesis requires the constriction of ESCRT-III filaments on the side of the midbody, where abscission occurs. After ESCRT recruitment at the midbody, it is not known how the ESCRT-III machinery localizes to the abscission site. To reveal novel actors involved in abscission, we obtained the proteome of intact, post-abscission midbodies (Flemmingsome) and identified 489 proteins enriched in this organelle. Among those proteins, we further characterized a plasma membrane-to-ESCRT module composed of the transmembrane proteoglycan syndecan-4, ALIX and syntenin, a protein that bridges ESCRT-III/ALIX to syndecans. The three proteins were highly recruited first at the midbody then at the abscission site, and their depletion delayed abscission. Mechanistically, direct interactions between ALIX, syntenin and syndecan-4 were essential for proper enrichment of the ESCRT-III machinery at the abscission site, but not at the midbody. We propose that the ESCRT-III machinery must be physically coupled to a membrane protein at the cytokinetic abscission site for efficient scission, revealing novel common requirements in cytokinesis, exosome formation and HIV budding.

cell biology↗