N-myristoylation by NMT1 is POTEE-dependent to stimulate liver tumorigenesis via differentially regulating ubiquitination of targets

Here, N-myristolyation, one kind post-translational modification, and its enzyme NMT1 but not NMT2, were found to be critical in liver cancer. Two categories of proteins, i.e. N-myristolyation down-regulated (NDP) and up-regulated protein (NUP) were revealed negatively and positively regulated by NMT1, respectively. Both NDP and NUP could be N-myristolyated by NMT1 indispensible of POTEE. However, N-myristolyation decreased and increased stability of NDP and NUP, respectively. NDP-specific binding protein RPL7A facilitated HISTIH4H, which has ubiquitin E3 ligase function, to ubiquitinate NDP. By contrast, NUP-specific binding protein HBB prevented NUP from ubiquitination by HISTIH4H. Notably, function of RPL7A and HBB were all NMT1-dependent. Moreover, NDP suppressed while NUP stimulated transformative phenotypes. Clinically, higher levels of NMT1 and NUP with lower levels of NDP had worse prognostic outcome. Collectively, N-myristolyation by NMT1 suppresses anti-tumorigenic NDP, whereas stimulates pro-tumorigenic NUP by interfering their ubiquitination to finally result in a pro-tumorigenic outcome in liver cancer.