MicroRNA (miRNA) comprise a large family of non-protein coding transcripts which regulate gene expression in diverse biological pathways of both plants and animals. We recently used a systematic proteomic approach to generate a protein interactome map of the human miRNA pathway involved in miRNA biogenesis and processing. The interactome expands the number of candidate proteins in the miRNA pathway and connects the network to other cellular processes. Functional analyses identified TRIM65 and at least 3 other proteins as novel regulators of the miRNA pathway. Biochemical studies established that TRIM65 forms stable complexes with TNRC6 proteins and these molecules co-localize in P-body-like structures. Gain of function and RNAi analyses reveal that TRIM65 negatively regulates miRNA-driven suppression of mRNA translation by targeting TNRC6 proteins for ubiquitination and degradation. The potential molecular mechanisms which regulate TRIM65 catalytic activity are discussed.
Keywords: AGO, Argonaute; AP-MS, Affinity purification coupled with mass spectrometry; DGCR8, DiGeorge syndrome critical region gene 8; HCIP, High confidence interacting protein; IMP-1, IGF2 mRNA-binding protein 1; MOV10, Moloney leukemia virus 10; MiRNA, microRNA; PDCD4, Programmed cell death 4; PTEN, Phosphatase and tensin homolog; RISC, RNA-induced silencing complex; RNA-induced silencing complex; TARBP2, TAR (HIV-1) RNA binding protein 2; TNRC6; TNRC6, Trinucleotide repeat containing 6; TRIM65, Tripartite Motif-Containing 65; interactome; proteomics; tripartite motif proteins; ubiquitin E3 ligase.