Cav‐3 is associated with and regulates the actin cytoskeleton in BV2 cells

Abstract

Caveolins are canonically localized to plasma membrane (PM) caveolae. BV2 cells express all three caveolin isoforms (Cav‐1, ‐2, ‐3). Cav‐1 is localized to the PM but Cav‐3 is concentrated at cell processes and perinuclear. When BV2 cells are grown in DMEM 10% FBS (D10%), a rounded morphology with limited Cav‐3 expression is exhibited. In serum free media (HYC), expression of Cav‐3 increases and can be reversed by D10% incubation. Sucrose density fractionation shows Cav‐3 in heavy membrane fractions with limited protein in buoyant lipid raft fractions. Cell compartmentation shows partitioning of Cav‐1 specifically in the membrane, while Cav‐3 partitions to the cytoskeleton. Analysis with actin or microtubule disrupting agents reveals a close connection between Cav‐1 and Cav‐3 with the cytoskeleton. In HYC cultures treated with nocodazole or D10% with taxol, Cav‐1 was increased in HYC and decreased in D10%. In HYC cultures treated with cytochalasin D or D10% with jasplakinoide (JASP), Cav‐3 expression was decreased in HYC and increased in D10%. HYC cultures treated with JASP redistributed Cav‐3 to PM. G‐actin was sequestered with latruculin B resulting in reduced cell proliferation in HYC or enhanced proliferation in D10%. Cav‐3, not Cav‐1, was observed associated with mitotic spindles. Thus, we propose a novel mechanistic role for Cav‐3 in the regulation of microglia morphology and mitosis.