Yoon Ki Kim

Nonsense-mediated mRNA decay (NMD), which is arguably the best-characterized translation-dependent regulatory pathway in mammals, selectively degrades mRNAs as a means of post-transcriptional gene control. Control can be for the purpose of ensuring the quality of gene expression. Alternatively, control can facilitate the adaptation of cells to changes in their environment. The key to NMD, no matter what its purpose, is the ATP-dependent RNA helicase upstream frameshift 1 (UPF1), without which NM

Translational initiation of the human BiP mRNA is directed by an internal ribosomal entry site (IRES) located in the 5'-untranslated region (5'-UTR). In order to understand the mechanism of the IRES-dependent translation of BiP mRNA, cellular proteins interacting with the BiP IRES were investigated. La autoantigen, which augments the translation of polioviral mRNA and hepatitis C viral mRNA, bound specifically to the second half of the 5'-UTR of the BiP IRES and enhanced translation of BiP mRNA

Hepatitis C virus (HCV) is a positive-sense RNA virus approximately 9600 bases long. An internal ribosomal entry site (IRES) spans the 5' nontranslated region, which is the most conserved and highly structured region of the HCV genome. In this study, we demonstrate that nucleotides 428-442 of the HCV core-coding sequence anneal to nucleotides 24-38 of the 5'NTR, and that this RNA-RNA interaction modulates IRES-dependent translation in rabbit reticulocyte lysate and in HepG2 cells. The inclusion

The promoter of the human thymidine kinase gene contains cis-regulatory elements responsible for its cell-cycle-regulated expression. We report here that a 70-bp region between -133 and -64 is sufficient to confer cell cycle regulation on a heterologous promoter. The 20-bp region between -64 and -83, which contains an inverted CCAAT motif, is important for transcriptional stimulation of this functional unit. The sequence of this CCAAT motif is nearly identical to the consensus sequence for the t

Exon junction complexes (EJCs) loaded onto spliced mRNAs during splicing serve as molecular markers for various post-transcriptional gene-regulatory processes, including nonsense-mediated mRNA decay (NMD). Although the composition and structure of EJCs are well characterized, the mechanism regulating EJC deposition remains unknown. Here we find that threonine 163 (T163) within the RNA-binding motif of eIF4A3 (a core EJC component) is phosphorylated by cyclin-dependent protein kinases 1 and 2 in

N⁶-Methyladenosine (m⁶A), the most abundant internal mRNA modification, affects multiple steps in gene expression. Mechanistically, the binding of YTHDF2 to m⁶A on mRNAs elicits rapid mRNA degradation by recruiting several RNA degrading enzymes. Here, we show that N¹-methyladenosine (m¹A), another type of RNA modification, accelerates rapid m⁶A RNA degradation. We identify HRSP12 as an RNA-binding protein that recognizes m<sup>1</

N⁶-methyladenosine (m⁶A) is the most prevalent internal modification in eukaryotic mRNAs and affects RNA processing and metabolism. When YTHDF2, an m⁶A-recognizing protein, binds to m⁶A, it facilitates the destabilization of m⁶A-containing RNAs (m⁶A RNAs). Here, we demonstrate that upstream frameshift 1 (UPF1), a key factor for nonsense-mediated mRNA decay, interacts with YTHDF2, thereby triggering rapid degradation of m<sup>6</su