SQSTM1/p62 and Hepatic Mallory Denk Body Formation in Alcohol-Associated Liver Disease.

SQSTM1/p62 (hereafter referred to as p62) is an autophagy receptor protein for selective autophagy primarily due to its direct interaction with the microtubule light chain 3 (LC3) protein that specifically localizes on autophagosome membranes. As a result, impaired autophagy leads to the accumulation of p62. p62 is also a common component of many human liver disease-related cellular inclusion bodies, such as Mallory-Denk Bodies (MDB), intracytoplasmic hyaline bodies (IHBs), α1 antitrypsin aggregates, as well as p62 bodies/condensates. p62 also acts as an intracellular signaling hub, and it involves multiple signaling pathways including nuclear factor erythroid 2-related factor 2 (NRF2), nuclear factor kappa B (NFκB), and the mechanistic target of rapamycin (mTOR), which are critical for oxidative stress, inflammation, cell survival, metabolism, and liver tumorigenesis. In this review, we will discuss the recent insights of p62 in protein quality control, including the role of p62 in the formation and degradation of p62 stress granules and protein aggregates as well as regulation of multiple signaling pathways in the pathogenesis of alcohol-associated liver disease (ALD).