RESUMO
Diacylglycerol is necessary for trans-Golgi network (TGN) to cell surface transport, but its functional relevance in the early secretory pathway is unclear. Although depletion of diacylglycerol did not affect ER-to-Golgi transport, it led to a redistribution of the KDEL receptor to the Golgi, indicating that Golgi-to-ER transport was perturbed. Electron microscopy revealed an accumulation of COPI-coated membrane profiles close to the Golgi cisternae. Electron tomography showed that the majority of these membrane profiles originate from coated buds, indicating a block in membrane fission. Under these conditions the Golgi-associated pool of ARFGAP1 was reduced, but there was no effect on the binding of coatomer or the membrane fission protein CtBP3/BARS to the Golgi. The addition of 1,2-dioctanoyl-sn-glycerol or the diacylglycerol analogue phorbol 12,13-dibutyrate reversed the effects of endogenous diacylglycerol depletion. Our findings implicate diacylglycerol in the retrograde transport of proteins from Golgi to the ER and suggest that it plays a critical role at a late stage of COPI vesicle formation.
Assuntos
Vesículas Revestidas pelo Complexo de Proteína do Envoltório/metabolismo , Complexo I de Proteína do Envoltório/metabolismo , Diglicerídeos/metabolismo , Retículo Endoplasmático/metabolismo , Complexo de Golgi/metabolismo , Animais , Transporte Biológico/efeitos dos fármacos , Brefeldina A/farmacologia , Células COS , Proteínas de Transporte/metabolismo , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Chlorocebus aethiops , Diglicerídeos/farmacologia , Retículo Endoplasmático/efeitos dos fármacos , Retículo Endoplasmático/ultraestrutura , Estrenos/farmacologia , Proteínas Ativadoras de GTPase/metabolismo , Complexo de Golgi/efeitos dos fármacos , Complexo de Golgi/ultraestrutura , Células HeLa , Humanos , Dibutirato de 12,13-Forbol/farmacologia , Propranolol/farmacologia , Pirrolidinonas/farmacologia , Ratos , Receptores de Peptídeos/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
Secretion and endocytosis are highly dynamic processes that are sensitive to external stimuli. Thus, in multicellular organisms, different cell types utilize specialised pathways of intracellular membrane traffic to facilitate specific physiological functions. In addition to the complex internal molecular factors that govern sorting functions and fission or fusion of transport carriers, the actin cytoskeleton plays an important role in both the endocytic and secretory pathways. The interaction between the actin cytoskeleton and membrane trafficking is not restricted to transport processes: it also appears to be directly involved in the biogenesis of Golgi-derived transport carriers (budding and fission processes) and in the maintenance of the unique flat shape of Golgi cisternae.
Assuntos
Actinas/metabolismo , Complexo de Golgi/metabolismo , Neurônios/metabolismo , Citoesqueleto de Actina/metabolismo , Animais , Citoesqueleto/metabolismo , Humanos , Modelos Biológicos , Proteínas Motores Moleculares/metabolismo , Neurônios/citologia , Transporte ProteicoRESUMO
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