Dimt1, short for dimethyladenosine transferase 1, is an evolutionarily conserved RNA N6,6-dimethyladenosine (m26,6A) methyltransferase. It plays a crucial role in ribosome biogenesis, and its catalytic activity is indispensable for cell viability and protein synthesis. Dimt1 is involved in pathways related to inter-generational hormesis, ribosomal processing, and may impact mitochondrial function. Genetic models such as Caenorhabditis elegans are valuable for studying its functions [1,2].

In C. elegans, parental starvation leads to inter-generational hormesis in progeny, which is accompanied by an increase in N6'-dimethyl adenosine (m6,2A) on 18S ribosomal RNA. DIMT-1/DIMT1 was identified as the m6,2A methyltransferase required for this inter-generational hormesis [1]. In human cells, DIMT1 generates m26,6A not only in 18S rRNA but also in small RNAs, and cells expressing catalytically inactive DIMT1 variants show decreased protein synthesis and cell viability [2]. In acute myeloid leukemia (AML), DIMT1 is essential for proliferation through a non-catalytic function. Targeting a positively charged cleft of DIMT1, remote from the catalytic site, weakens its binding to rRNA and mislocalizes it, affecting AML cell proliferation [3]. In gastric carcinoma, high DIMT1 expression correlates with tumor progression and poor prognosis [4]. In insects and C. elegans, the putative ortholog of human DIMT1 regulates lifespan [5]. In β-cells, DIMT1 controls protein synthesis, mitochondrial function, and insulin secretion, and its deficiency leads to perturbed insulin secretion, a potential pathogenic process in type 2 diabetes (T2D) [6]. In thyroid cancer, a PARP inhibitor inhibits DIMT1 transcription, leading to global translation inhibition [7]. Structural studies in human cells show that the catalytic activity of DIMT1 is involved in protein translation, and its overall protein scaffold is essential for 40S assembly [8]. Structural and functional characterization of archaeal DIMT1 reveals unique protein dynamics for efficient catalysis [9]. A study on the positively charged cleft of DIMT1 identified the minimum region to target for cell proliferation regulation [10].

In conclusion, Dimt1 is essential for ribosome biogenesis, cell viability, and protein synthesis. Model-based research, including studies in C. elegans, insects, and human cell lines, has revealed its roles in various biological processes and diseases such as inter-generational hormesis, cancer (AML, gastric carcinoma, thyroid cancer), lifespan regulation, and T2D. These findings contribute to understanding the molecular mechanisms underlying these biological phenomena and diseases, potentially guiding the development of new therapeutic strategies.