Mtr4, also known as MTREX, is a Ski2-like RNA helicase. It plays a central role in RNA surveillance and degradation pathways as an activator of the RNA exosome. This function is crucial for maintaining proper RNA metabolism, which impacts various biological processes such as ribosome biogenesis, cell cycle regulation, and immune response [1,5,6].

In terms of specific findings, in ribosome biogenesis, the MTR4 adaptor PICT1, a mammalian ortholog of yeast Nop53, interacts with MTR4 and the exosome in an AIM-dependent manner. PICT1 is involved in two distinct pre-rRNA processing steps during 60S ribosome generation, and the recruitment of MTR4 and the RNA exosome via the AIM sequence is required only during the late processing step [5].

In HIV-1 latency, MTR4, along with MATR3, is involved in the regulation of unspliced HIV-1 RNA. They coexist in the same ribonucleoprotein complex, with MTR4 degrading the RNA, and Rev orchestrating this regulatory switch. Also, MTR4 is part of a nuclear RNA surveillance complex that silences HIV-1 transcription [2,3].

In the regulation of lncRNA stability, hnRNPH1 associates with MTR4 to regulate the stability of NEAT1v2, which is critical for IL8 expression [4].

In conclusion, Mtr4 is essential for RNA-related biological processes. Its role in ribosome biogenesis, HIV-1 latency, and lncRNA-mediated gene expression regulation has been revealed through functional studies. Understanding Mtr4's functions may open new avenues for therapeutic intervention in diseases related to abnormal RNA metabolism, such as HIV-1 infection [2,3].