Identification of DENR-interacting proteins in NIH3t3 cells using a co-IP MS-MS approach on endogenously tagged DENR.

ABSTRACT: Among the transcript features that regulate translation rate, upstream open reading frames (uORFs) have emerged as a major class of inhibitory elements which limit how many scanning ribosomes reach the start codon of the main protein coding sequence (CDS). Two processes are implicated in ensuring that CDS translation of uORF-containing transcripts can take place nevertheless: first, leaky-scanning, which involves the bypassing of uORF start codons by the scanning 40S ribosome, and second, re-initiation (REI), which allows the 40S subunit of the ribosome that terminated on the uORF stop codon to resume scanning to reach a downstream start codon. REI has remained particularly enigmatic, as it is at odds with generally accepted principles of conventional translation initiation, termination and post-termination subunit recycling. The heterodimer MCTS1-DENR is the first re-initiation-specific factor that has been identified. MCTS1 has been described as the only obligatory partner of DENR. Nevertheless, MCTS1 depletion phenotypes do not always copy the phenotype of DENR depletion in mammalian cells, suggesting that another partner could compensate for the lack of MCTS1. We performed co-immunoprecipitation followed by MS-MS analysis of endogenously FLAG-tagged DENR and identified MCTS2 as a new protein partner. MCTS2 is a homolog and retrogene copy of MCTS1. Downstream analyses demonstrated that MCTS2-DENR was able to promote re-initiation in vitro and showed that Mcts2 mRNA was highly abundant and the protein at least as efficiently synthesized as MCTS1 in NIH3t3 cells, implying that MCTS2 might be the main expressed variant in certain cell types.

INSTRUMENT(S): Orbitrap Exploris 480

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Cell Culture, Fibroblast

SUBMITTER: David Gatfield  

LAB HEAD: David Gatfield

PROVIDER: PXD051482 | Pride | 2024-11-01

REPOSITORIES: Pride