Dissociation of functional roles of dynamin in receptor-mediated endocytosis and mitogenic signal transduction

Dynamin plays a critical role in the membrane fission mechanism that mediat es regulated endocytosis of many G protein-coupled receptors. in addition, dynamin is required for ligand-induced activation of mitogen-activated prot ein kinase by certain receptors, raising a general question about the role of dynamin in mitogenic signal transduction. Here we report that endocytosi s of mu and delta opioid receptors is not required for efficient ligand-ind uced activation of mitogen-activated protein kinase. Nevertheless, mitogeni c signaling mediated by these receptors is specifically dynamin-dependent. Thus a functional role of dynamin in mitogenic signaling can be dissociated from its role in receptor-mediated endocytosis, suggesting a previously un identified and distinct role of dynamin in signal transduction by certain G protein-coupled receptors.