TRMT10A dysfunction perturbs codon translation of initiator methionine and glutamine and impairs brain functions in mice.

In higher eukaryotes, tRNA methyltransferase 10A (TRMT10A) is responsible for N1-methylguanosine modification at position nine of various cytoplasmic tRNAs. Pathogenic mutations in TRMT10A cause intellectual disability, microcephaly, diabetes, and short stature in humans, and generate cytotoxic tRNA fragments in cultured cells; however, it is not clear how TRMT10A supports codon translation or brain functions. Here, we generated Trmt10a null mice and showed that tRNAGln(CUG) and initiator methionine tRNA levels were universally decreased in various tissues; the same was true in a human cell line lacking TRMT10A. Ribosome profiling of mouse brain revealed that dysfunction of TRMT10A causes ribosome slowdown at the Gln(CAG) codon and increases translation of Atf4 due to higher frequency of leaky scanning of its upstream open reading frames. Broadly speaking, translation of a subset of mRNAs, especially those for neuronal structures, is perturbed in the mutant brain. Despite not showing discernable defects in the pancreas, liver, or kidney, Trmt10a null mice showed lower body weight and smaller hippocampal postsynaptic densities, which is associated with defective synaptic plasticity and memory. Taken together, our study provides mechanistic insight into the roles of TRMT10A in the brain, and exemplifies the importance of universal tRNA modification during translation of specific codons.

Study Design of a Phase II Clinical Trial to Assess the Efficacy and Safety of Eperisone in Japanese Type 2 Diabetes Patients with Risk and Non-risk Alleles of CDKAL1.

Genetic variation in Cdk5 Regulatory Associated Protein 1-Like 1 (CDKAL1) is associated with the development of type 2 diabetes (T2D). Dysfunction of CDKAL1 impairs the translation of proinsulin, which leads to glucose intolerance. Eperisone, an antispasmodic agent, has been shown to ameliorate glucose intolerance in Cdkal1-deficient mice. We have launched a phase II clinical study to investigate the potential anti-diabetic effect of eperisone in T2D patients carrying risk or non-risk alleles of CDKAL1. The primary endpoint is the change of hemoglobin A1c (HbA1c) levels. We also examined whether the efficacy of eperisone in T2D patients is associated with CDKAL1 activity.

Questionnaire Survey Regarding Troubles and Concerns Related to Clinical Research Based on the Clinical Trial Act for Clinicians and Academics.

The Clinical Trial Act came into force in 2018 in Japan. A questionnaire survey was conducted with personnel at Kumamoto University Hospital engaged in research and development, to explore their perceptions of troubles and concerns about clinical research related to the Clinical Trial Act. We collected 127 comments about troubles and 149 about concerns. Text mining (co-occurrence network and hierarchical cluster analysis) was used to extract the characteristics or tendencies in these comments. The analysis extracted 18 key terms for troubles and 21 for concerns. Most troubles and concerns had to do with concrete examples of clinical research or protocols and biostatistics information. Our results emphasized the importance of clinical research support organizations, and suggested that appropriate workshops and information covering specific situations are necessary to perform clinical research under the new regime.

A case of cortisol producing adrenal adenoma associated with a latent aldosteronoma: usefulness of the ACTH loading test for the detection of covert aldosteronism in overt Cushing syndrome.

A 36-year-old woman with Cushing syndrome was evaluated for coexisting hyperaldosteronism, which was suggested by an abnormal response of the aldosterone-to-cortisol ratio in peripheral blood to the ACTH-administration despite a low basal aldosterone-to-renin ratio. Computed tomography revealed two independent tumors in the left adrenal gland, and adrenal venous sampling indicated hyperaldosteronism in addition to hypercortisolism in the same side. Postsurgical study including immunohistochemical analysis of steroidogenic enzymes suggested one adenoma to be cortisol-producing and the other, aldosterone-producing. The comorbidity of these different hormone-producing adenomas is not rare and careful pre-surgical evaluation is necessary to avoid post-surgical exacerbation of latent hyperaldosteronism.