The Globular Heads of the C1q Receptor Regulate Apoptosis in Human Extravillous Cytotrophoblast-derived Transformed Cells via a Mitochondria-dependent Pathway

Problem: The receptor for the globular head of human C1q (gC1qR) predominantly localizes to the mitochondrial matrix. gC1qR mediates many biological responses, including growth perturbations, morphological abnormalities and the initiation of apoptosis. The purpose of this study was to investigate the relationship between gC1qR expression, mitochondrial dysfunction and the regulation of apoptosis in human extravillous cytotrophoblast (EVCT)-derived transformed cell lines (HTR-8/SVneo and HPT-8). Method of study: gC1qR expression was examined in human placental villi using real-time qPCR and Western blot analysis. The apoptotic death of HTR-8/SVneo and HPT-8 cells was assessed using flow cytometric analysis. Mitochondrial function was assessed via ROS generation, the amount of cytosolic Ca²⁺ and changes in the mitochondrial membrane potential (Δψm). Results: The expression of the gC1qR gene was significantly increased in spontaneous abortion samples relative to induced abortion samples. HTR-8/SVneo and HPT-8 cells transfected with a gC1qR vector showed upregulation of cellular apoptosis and mitochondrial dysfunction, interestingly, which were abrogated by the addition of metformin. Metformin may protect mitochondrial function. Conclusion: These data support a mechanism whereby gC1qR induces apoptosis through mitochondria-dependent pathways in human EVCT-derived transformed cells.