ABSTRACT
CED-1 (cell death abnormal) is a transmembrane receptor involved in the recognition of "eat-me" signals displayed on the surface of apoptotic cells and thus central for the subsequent engulfment of the cell corpse in Caenorhabditis elegans. The roles of CED-1 in engulfment are well established, as are its downstream effectors. The latter include the adapter protein CED-6/GULP and the ATP-binding cassette family homolog CED-7. However, how CED-1 is maintained on the plasma membrane in the absence of engulfment is currently unknown. Here, we show that CED-6 and CED-7 have a novel role in maintaining CED-1 correctly on the plasma membrane. We propose that the underlying mechanism is via endocytosis as CED-6 and CED-7 act redundantly with clathrin and its adaptor, the Adaptor protein 2 complex, in ensuring correct CED-1 localization. In conclusion, CED-6 and CED-7 impact other cellular processes than engulfment of apoptotic cells.
Subject(s)
Caenorhabditis elegans Proteins , Caenorhabditis elegans , Cell Membrane , Clathrin , Endocytosis , Animals , Caenorhabditis elegans Proteins/metabolism , Caenorhabditis elegans Proteins/genetics , Caenorhabditis elegans/metabolism , Caenorhabditis elegans/genetics , Clathrin/metabolism , Cell Membrane/metabolism , Membrane Proteins/metabolism , Membrane Proteins/genetics , Apoptosis , ATP-Binding Cassette Transporters/metabolism , ATP-Binding Cassette Transporters/genetics , Adaptor Protein Complex 2/metabolism , Protein Transport , Apoptosis Regulatory ProteinsABSTRACT
Repeated weight loss cycles are associated with increased cardiovascular morbidity. Meal-induced thrombin formation, measured as prothrombin fragment 1+2 (F1+2), is observed in individuals with overweight after weight loss, and postprandial effects can be one of the mechanisms underlying harmful effects during intentional weight loss. We hypothesize that consumption of high-fat meals during intentional weight loss triggers a prothrombotic state by increasing postprandial F1+2 or decreasing fibrin clot lysis in individuals with obesity, and that the response associates with the gut bacteria composition. A cross-over meal study was conducted in patients admitted to bariatric surgery during dietary weight loss (N = 20) and surgical weight loss (N = 16) (weight loss groups). High-fat (67 E%) and low-fat (16 E%) meals were served at 08:15 and 10:00 on 2 study days. Blood samples collected at 08:00 (fasting), 12:00, and 14:00 were analyzed for triglycerides, activated factor VII (FVIIa), F1+2, D-dimer, fibrinogen, tissue factor , and fibrin clot lysis. The proportion of Gram-negative bacteria and bacterial diversity were analyzed in fecal samples obtained less than 24 hours before the meal test. Triglyceride and FVIIa increased after high-fat meals in both weight loss groups, whereas D-dimer (dietary group) and F1+2 decreased and tissue factor and fibrin clot lysis did not change. There was a negative association between the proportion of Gram-negative bacteria and changes in FVIIa in the surgery group. Postprandial FVII activation after high-fat meals is not accompanied by increased F1+2, irrespective of the weight loss intervention, but might be associated with the proportion of Gram-negative gut bacteria.