New Trick for the Old COP: Cellular Physiology of COPII Condensation in Lipoprotein Secretion

Products encoded by approximately 30% of the mammalian genome exit the endoplasmic reticulum via the coat complex II (COPII) system en route to their functional destination. Among these cargoes, APOB-containing lipoproteins stand out as abundant and bulky secretory particles with profound implications for human health and diseases. Recent insights into the specialized intracellular itinerary of lipoprotein metabolism and transport not only shed light on longstanding questions of lipid dynamics, but also highlight challenges faced by the COPII machinery in accommodating these complex, unconventional cargoes. Emerging evidence supports that tightly-regulated COPII condensation enables maximal capacity of cargo transport, providing a potential solution tailored for efficient lipoprotein delivery without affecting general protein secretion. This distinction suggests that targeting COPII condensation may provide new therapeutic strategies for lipid-associated diseases. Indeed, recent studies have identified manganese as a key modulator of this process, offering novel insights into its physiological relevance and potential translations.