Xenophagy Antibody Sampler Kit

Background

Xenophagy provides an important defense against foreign pathogens, such as bacteria and viruses, by targeting them for degradation through autophagy (1-3). Several well-known pathogens can be targeted for degradation through xenophagy, including Salmonella typhimurium, Streptococcus pyogenes, and Mycobacterium tuberculosis, and loss of core autophagy genes can result in enhanced vulnerability to these infections. Pathogens are generally targeted to LC3B or other Atg8 family members localized on autophagosome membranes. Sequestosome 1/p62-like receptors (SLRs) function as cargo receptors through ubiquitin-mediated interactions along with LIR-domain interactions with Atg8 proteins on the autophagosome. The SLR TAX1BP1 is recruited to ubiquitylated Salmonella and plays a key role in xenophagy (4). Another SLR NDP52 has also been reported to be required for xenophagy of several pathogens (5,6). LRSAM1 is an E3 ubiquitin ligase with a leucine-rich repeat recognized by microbial ligands and recruits NDP52 (7). In addition, galectins are a family of cytosolic lectins that are associated with phagophores and bacteria. Galectin-3 is recruited to bacterial membranes and is important for protection against Mycobacterium tuberculosis (8). TBK1 is a serine/threonine kinase that plays a major role in controlling autophagy by targeting substrates in the SLR family and the maturation of autophagosomes. TBK1 is phosphorylated at Ser172 within its activation loop, which is required for its kinase activity (9). Atg16L1 is a component of the Atg12-Atg5 conjugation system required for autophagosome maturation (10,11). ULK1-mediated phosphorylation of Atg16L1 at Ser278 promotes xenophagy (12).