Cell–matrix interaction via CD44 is independently regulated by different metalloproteinases activated in response to extracellular Ca2+ influx and PKC activation

TLDR

CD44 is an adhesion molecule that binds hyaluronic acid and undergoes sequential proteolytic cleavages of its ectodomain and intramembranous domain, with ectodomain cleavage triggered by extracellular Ca²⁺ influx or PKC activation. The study investigates how CD44-mediated cell‑matrix adhesion is terminated by two independent ADAM metalloproteinases, ADAM10 and ADAM17, differentially regulated by Ca²⁺ influx and PKC activation. Ca²⁺ influx activates ADAM10 via calmodulin association to cleave CD44 ectodomain, while phorbol ester–induced PKC and Rac activation stimulates ADAM17 to proteolyze CD44. Loss of ADAM10 blocks Ca²⁺‑induced cell detachment, and depletion of either ADAM10 or ADAM17 markedly suppresses CD44‑dependent cancer cell migration on hyaluronic acid but not fibronectin, underscoring the critical role of the spatio‑temporal regulation of these pathways in cell‑matrix interaction and migration.

Abstract

CD44 is an adhesion molecule that interacts with hyaluronic acid (HA) and undergoes sequential proteolytic cleavages in its ectodomain and intramembranous domain. The ectodomain cleavage is triggered by extracellular Ca(2+) influx or the activation of protein kinase C. Here we show that CD44-mediated cell-matrix adhesion is terminated by two independent ADAM family metalloproteinases, ADAM10 and ADAM17, differentially regulated in response to those stimuli. Ca(2+) influx activates ADAM10 by regulating the association between calmodulin and ADAM10, leading to CD44 ectodomain cleavage. Depletion of ADAM10 strongly inhibits the Ca(2+) influx-induced cell detachment from matrix. On the other hand, phorbol ester stimulation activates ADAM17 through the activation of PKC and small GTPase Rac, inducing proteolysis of CD44. Furthermore, depletion of ADAM10 or ADAM17 markedly suppressed CD44-dependent cancer cell migration on HA, but not on fibronectin. The spatio-temporal regulation of two independent signaling pathways for CD44 cleavage plays a crucial role in cell-matrix interaction and cell migration.