Anti-DRAM1 monoclonal antibody Made to order

Ginsenoside Rh2 is a potential pharmacologically active metabolite of ginseng. Previously, we have reported that an octyl ester derivative of ginsenoside Rh2 (Rh2-O), has been confirmed to possess higher bioavailability and anticancer effect than Rh2 in vitro. In order to better assess the possibility that Rh2-O could be used as an anticancer compound, the underlying mechanism was investigated in this study. The present results revealed that lysosomal destabilization was involved in the early stage of cell apoptosis in HepG2 cells induced by Rh2-O. Rh2-O could induce an early lysosomal membrane permeabilization with the release of lysosomal protease cathepsins to the cytosol in HepG2 cells. The Cat B inhibitor (leu) and Cat D inhibitor (pepA) inhibited Rh2-O-induced HepG2 apoptosis as well as tBid production and Delta phi m depolarization, indicating that lysosomal permeabilization occurred upstream of mitochondrial dysfunction. In addition, Rh2-O induced a significant increase in the protein levels of DRAM1 and Bax (p < 0.05) in lysosomes of HepG2 cells. Knockdown of Bax partially inhibited Rh2-O-induced Cat D release from lysosomes. Thus it was concluded that Rh2-O induced apoptosis of HepG2 cells through activation of the lysosomal-mitochondrial apoptotic pathway involving the translocation of Bax to the lysosome.

Autophagy is an important defense mechanism against mycobacteria, the causative agents of tuberculosis. The molecular mechanisms that link mycobacterial recognition to autophagy remain unclear. Our analysis in zebrafish and human macrophage models of mycobacterial infection reveals that the DNA damage-regulated autophagy modulator DRAM1 functions downstream of pathogen recognition by the Toll-like receptor (TLR)/interleukin-1 receptor (IL1R)-MYD88-NF-kappa B innate immune sensing pathway to activate selective autophagy. Mycobacterial infection of human macrophages and zebrafish embryos induced DRAM1 expression in a MYD88 and NF-kappa B-dependent manner. DRAM1 knockdown increased mycobacterial infection, whereas overexpression lowered infection by hyperactivating autophagy. DRAM1-mediated selective autophagic defenses require the cytosolic DNA sensor STING and the selective autophagy receptor p62/SQSTM1. Contrary to its known role in autophagy-mediated cell death and cancer, this DRAM1 function is p53 independent. We propose that DRAM1 mediates autophagic defense against a broader range of intracellular pathogens, since DRAM1 expression was also induced by the common bacterial endotoxin lipopolysaccharide.