C1q is related to microglial phagocytosis in the hippocampus in physiological conditions

The complement protein C1q has lately emerged as an important molecule in the clearance of apoptotic cells. However, its role in the brain in physiological conditions is less explored. Using as a model the adult neurogenic cascade, where newborn cells undergo apoptosis and are phagocytosed by microglia, in the present study we have discovered three major findings using immunofluorescence and RTqPCR from FACSsorted microglia in fms-EGFP mice. First, we found that C1q is mainly produced by microglia in the hippocampus in physiological conditions. Second, we observed a relationship between phagocytic microglia and C1q, as suggested by the presence of C1q within the majority of the microglial phagocytic pouches. Finally, we discovered that the functions of C1q in microglia may go beyond phagocytosis, as C1q was also found in non-phagocytic microglia.