BEGIN:VCALENDAR VERSION:2.0 PRODID:-//jEvents 2.0 for Joomla//EN CALSCALE:GREGORIAN METHOD:PUBLISH BEGIN:VEVENT UID:95d6780910d26d3cf99f154149344971 CATEGORIES:Colloquium CREATED:20220728T150105 SUMMARY:Professor Matthew Tyska, Vanderbilt University School of Medicine DESCRIPTION:
Shaping the epithelial cell surface with actin  ;bundling proteins
During diffe rentiation, enterocytes build an extensive apical array of microvilli& nbsp;known as the brush border, which serves to amplify the plasma membrane surface area available for nutrient absorption. In add ition to serving as the sole site of nutrient uptake, brush border&nbs p;microvilli also provide an anchoring point for the glycocalyx and re gulate interactions with luminal microbes. An individual microvillus&n bsp;is simple in structure, consisting of a supporting core of ~25 act in filaments bundled in parallel by villin, fimbrin, and esp in. Remarkably, microvilli biogenesis persists in mice lacking al l three of these factors, suggesting the existence of unknown bundlers . We identified Mitotic Spindle Positioning (MISP) as an actin binding  ;factor that localizes specifically to the rootlet end of the microvil lus. MISP promotes rootlet elongation in cells, and purified MISP exhibits potent filament bundling activity in vitro. MISP-b undled filaments also recruit fimbrin, which further elongates and&nbs p;stabilizes bundles. MISP confinement to the rootlet is enforced by e zrin, which prevents decoration of the membrane-wrapped distal en d of the core bundle. These discoveries reveal how enterocytes op timize apical membrane surface area and offer insight on the rema rkable robustness of microvilli biogenesis.
Hosted by Professor Zheng Shi
Hybrid seminar:&n
bsp;On-site location is CCB-1303; for Zoom meeting in
formation, please contact Loretta Lupo at
Shaping the epithelial cel l surface with actin bundling proteins
During differentiation, enterocytes build an extensive ap ical array of microvilli known as the brush border, which serves to am plify the plasma membrane surface area available for nutrien t absorption. In addition to serving as the sole site of nutrient uptake, brush border microvilli also provide an anchoring point for t he glycocalyx and regulate interactions with luminal microbes. An individual microvillus is simple in structure, consisting of a s upporting core of ~25 actin filaments bundled in parallel by  ;villin, fimbrin, and espin. Remarkably, microvilli biogenesis persists in& nbsp;mice lacking all three of these factors, suggesting the existence of unknown bundlers. We identified Mitotic Spindle Positioning (MISP) as an actin binding factor that localizes specifically to the ro otlet end of the microvillus. MISP promotes rootlet elongation in cells, and purified MISP exhibits potent filament bundling activity&n bsp;in vitro. MISP-bundled filaments also recruit fimbrin, which further elongates and stabilizes bundles. MISP confinement to the rootlet is enforced by ezrin, which prevents decoration of the m embrane-wrapped distal end of the core bundle. These discoveries revea l how enterocytes optimize apical membrane surface area and offer  ;insight on the remarkable robustness of microvilli biogenesis.
Hosted by Professor Zheng Shi
Hybrid seminar: On-site location is CCB-
1303; for Zoom meeting information, please contact Loretta Lupo at
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