Calpains Orchestrate Secretion of Annexin-containing Microvesicles during Membrane Repair.

Microvesicles (MVs) are membrane-enclosed, plasma membrane-derived particles released by cells from all branches of life. MVs have utility as disease biomarkers and may participate in intercellular communication; however, physiological processes that induce their secretion are not known. Here, we isolate and characterize annexin-containing MVs and show that these vesicles are secreted in response to the calcium influx caused by membrane damage.

Annexin A6 mediates calcium-dependent exosome secretion during plasma membrane repair.

Exosomes are an extracellular vesicle (EV) subtype that is secreted upon the fusion of multivesicular bodies (MVBs) with the plasma membrane. Exosomes may participate in intercellular communication and have utility as disease biomarkers; however, little is known regarding the physiological stimuli that induce their secretion. Ca influx promotes exosome secretion, raising the possibility that exosomes are secreted during the Ca-dependent plasma membrane repair of tissues damaged by mechanical stress in vivo.

The Gα-interacting vesicle-associated protein interacts with and promotes cell surface localization of GRP78 during endoplasmic reticulum stress.

Cell surface translocation of the chaperone glucose-regulated protein 78 kDa (GRP78) is a key event that promotes cancer cell survival during endoplasmic reticulum (ER) stress. Here, we identify Gα-interacting vesicle-associated protein (GIV) - an enhancer of prosurvival signaling during ER stress - as a binding partner of GRP78. We show that GIV and GRP78 interact in an ER stress-dependent manner through their respective carboxyl terminal domains and that GIV aids in the localization of GRP78 to the plasma membrane.

Identification and characterization of a novel phosphoregulatory site on cyclin-dependent kinase 5.

Cyclin-dependent kinase 5 (CDK5) is a serine/threonine kinase essential for embryonic development whose overactivation has been implicated in several pathologies including neurodegeneration, cancer cell metastasis and type II diabetes. Therefore, it is important to investigate molecular mechanism(s) that mediate regulation of CDK5 activity. Here we identify and characterize a novel phosphoregulatory site on CDK5.