Centrosome-organized plasma membrane infoldings linked to growth of a cortical actin domain

Regulated cell shape change requires the induction of cortical cytoskeletal domains. Actin is a cytoskeleton protein that makes up the cortex and drives cell shape change. Signals to induce actin polymerization can come from external or internal cues. Often, local changes to plasma membrane (PM) topography are involved in mediating cell shape change. The centrosome is an organelle that can organize cortical domains and affect PM topography by locally pulling the PM inward. Is the role of the centrosome in organizing cortical domains and changing PM topography coupled? At the syncytial Drosophila embryo cortex, centrosome-induced actin caps grow into dome-like compartments for mitoses. We found the nascent cap to be a collection of PM folds and tubules formed over the astral centrosomal MT array. The localized infoldings require centrosome and dynein activities, and myosin-based surface tension prevents them elsewhere. Centrosome-engaged PM infoldings become specifically enriched with an Arp2/3 induction pathway. Arp2/3 actin network growth between the infoldings counterbalances centrosomal pulling forces and disperses the folds for actin cap expansion. Abnormal domain topography with either centrosome or Arp2/3 disruption correlates with decreased exocytic vesicle association. Together, our data implicate centrosome-organized PM infoldings in coordinating Arp2/3 network growth and exocytosis in cortical domain assembly.

Department dc:contributor.department

Cell and Systems Biology

Year dc:date.issued

2025

Author dc:creator

• Tam, Rebecca

Advisor dc:contributor.advisor

• Harris, Tony TJCH

Handle dc:identifier.uri

https://hdl.handle.net/1807/144921

OAI identifier oai:identifier

oai:utoronto.scholaris.ca:1807/144921