MHC class II fine tuning by ubiquitination: lesson from MARCHs.

Ubiquitination, a posttranscriptional modification, has been known to contribute to many aspects of cellular event (e.g., protein quality control, signal transduction). In 2007 and 2016, we reported physiological E3 ubiquitin ligases for MHC class II; these are membrane-associated ring-CH-type finger (MARCH)-1 and MARCH-8. Importantly, MARCH-1 and -8 are structurally close to each other, but have different expression profiles. MARCH-1 and -8 are expressed at secondary lymphoid organs and thymic epithelial cells, respectively. These findings suggest contribution of MARCHs to immunological disorders in human; however, its contribution remains to be elucidated. In this review, recent progress on MARCHs will be summarized from molecular and/or immunological point of view and future direction would be discussed.