Structural basis for the sequence-specific RNA-recognition mechanism of human CUG-BP1 RRM3

The CUG-binding protein 1 (CUG-BP1) is a member of the CUG-BP1 and ETR-like factors (CELF) family or the Bruno-like family and is involved in the control of splicing, translation and mRNA degradation. Several target RNA sequences of CUG-BP1 have been predicted, such as the CUG triplet repeat, the GU-rich sequences and the AU-rich element of nuclear pre-mRNAs and/or cytoplasmic mRNA. CUG-BP1 has three RNA-recognition motifs (RRMs), among which the third RRM (RRM3) can bind to the target RNAs on its own. In this study, we solved the solution structure of the CUG-BP1 RRM3 by hetero-nuclear NMR spectroscopy. The CUG-BP1 RRM3 exhibited a noncanonical RRM fold, with the four-stranded b-sheet surface tightly associated with the N-terminal extension. Furthermore, we determined the solution structure of the CUG-BP1 RRM3 in the complex with (UG)3 RNA, and discovered that the UGU trinucleotide is specifically recognized through extensive stacking interactions and hydrogen bonds within the pocket formed by the b-sheet surface and the N-terminal extension. This study revealed the unique mechanism that enables the CUG-BP1 RRM3 to discriminate the short RNA segment from other sequences, thus providing the molecular basis for the comprehension of the role of the RRM3s in the CELF/Bruno-like family

Structural basis for the dual RNA-recognition modes of human Tra2-beta RRM

Human Transformer2-beta (hTra2-beta) is an important member of the serine/arginine-rich protein family, and contains one RNA recognition motif (RRM). It controls the alternative splicing of several pre-mRNAs, including those of the calcitonin/calcitonin gene-related peptide (CGRP), the survival motor neuron 1 (SMN1) protein and the tau protein. Accordingly, the RRM of hTra2-beta specifically binds to two types of RNA sequences [the CAA and (GAA)2 sequences]. We determined the solution structure of the hTra2-beta RRM (spanning residues Asn110–Thr201), which not only has a canonical RRM fold, but also an unusual alignment of the aromatic amino acids on the beta-sheet surface. We then solved the complex structure of the hTra2-beta RRM with the (GAA)2 sequence, and found that the AGAA tetra-nucleotide was specifically recognized through hydrogen-bond formation with several amino acids on the N- and C-terminal extensions, as well as stacking interactions mediated by the unusually aligned aromatic rings on the beta-sheet surface. Further NMR experiments revealed that the hTra2-beta RRM recognizes the CAA sequence when it is integrated in the stem-loop structure. This study indicates that the hTra2-beta RRM recognizes two types of RNA sequences in different RNA binding modes

Conditioned medium from stem cells derived from human exfoliated deciduous teeth ameliorates NASH via the Gut-Liver axis

Non-alcoholic steatohepatitis (NASH) occurrence has been increasing and is becoming a major cause of liver cirrhosis and liver cancer. However, effective treatments for NASH are still lacking. We examined the benefits of serum-free conditioned medium from stem cells derived from human exfoliated deciduous teeth (SHED-CM) on a murine non-alcoholic steatohepatitis (NASH) model induced by a combination of Western diet (WD) and repeated administration of low doses of carbon tetrachloride intraperitoneally, focusing on the gut-liver axis. We showed that repeated intravenous administration of SHED-CM significantly ameliorated histological liver fibrosis and inflammation in a murine NASH model. SHED-CM inhibited parenchymal cell apoptosis and reduced the activation of inflammatory macrophages. Gene expression of pro-inflammatory and pro-fibrotic mediators (such as Tnf-α, Tgf-β, and Ccl-2) in the liver was reduced in mice treated with SHED-CM. Furthermore, SHED-CM protected intestinal tight junctions and maintained intestinal barrier function, while suppressing gene expression of the receptor for endotoxin, Toll-like receptor 4, in the liver. SHED-CM promoted the recovery of Caco-2 monolayer dysfunction induced by IFN-γ and TNF-α in vitro. Our findings suggest that SHED-CM may inhibit NASH fibrosis via the gut-liver axis, in addition to its protective effect on hepatocytes and the induction of macrophages with unique anti-inflammatory phenotypes

The RRM domain of poly(A)-specific ribonuclease has a noncanonical binding site for mRNA cap analog recognition

The degradation of the poly(A) tail is crucial for posttranscriptional gene regulation and for quality control of mRNA. Poly(A)-specific ribonuclease (PARN) is one of the major mammalian 3′ specific exo-ribonucleases involved in the degradation of the mRNA poly(A) tail, and it is also involved in the regulation of translation in early embryonic development. The interaction between PARN and the m7GpppG cap of mRNA plays a key role in stimulating the rate of deadenylation. Here we report the solution structures of the cap-binding domain of mouse PARN with and without the m7GpppG cap analog. The structure of the cap-binding domain adopts the RNA recognition motif (RRM) with a characteristic α-helical extension at its C-terminus, which covers the β-sheet surface (hereafter referred to as PARN RRM). In the complex structure of PARN RRM with the cap analog, the base of the N7-methyl guanosine (m7G) of the cap analog stacks with the solvent-exposed aromatic side chain of the distinctive tryptophan residue 468, located at the C-terminal end of the second β-strand. These unique structural features in PARN RRM reveal a novel cap-binding mode, which is distinct from the nucleotide recognition mode of the canonical RRM domains

DOCK2 is involved in the host genetics and biology of severe COVID-19

「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target

北海道医療大学歯学部附属病院入院患者の臨床統計学的観察

北海道医療大学歯学部付属病院の外来は1978年12月に開始し,入院病棟は1980年6月に24床で開始した.これまでの25年間における病棟入院患者の臨床統計的観察を行ったので報告する.結果は以下に示す.1.総入院患者数は3055例で総歯科新患の10.8%を占めていた.2.口腔外科疾患別では,顎変形症が最も多く393例で入院患者の12.9%を占めていた.3.病床稼働率は17.7%で,平均在院日数は14.2日で経年的に減少傾向にあった.4.25年間の入院診療報酬額は9億5715万円で歯科診療報酬額の20.4%を占めていた.The outpatient division of the Dental School hospital of the Health Sciences University of Hokkaido started in December 1978, and a hospitalization ward started with 24 beds opened in June 1978, and closed in April, 2005. Clinico-statistical observations for 25 the years while the inpatient division, was opened were evaluated. 1. The total number of inpatients was 3055, and comprised 11.8% in all initial patients of the dental hospital for the 25 years. 2. Patients with jaw deformities were the most common, 393 and comprised 12.4% of all hospitalized patients with oral and maxillofacial surgical complaints. 3. The rate of occupiod beds the operating bed ratio was 17.7% and the average length of hospitalization was 14.2 days. This number showed a tendency to decrease over the years. 4. The income from hospitalized care was 957.15 million yen and it comprised 20.4% of the total income of the dental department

北海道医療大学歯学部附属病院における顎矯正手術患者の臨床統計学的観察

A total of 55 patients who underwent orthognathic surgery from July 2002 to June 2005, were observed clinicostatistically. The results may be summarized as follows: 1. There were 11 males and 44 females. 2. The average age was 27.7 years, with an average of 22.3 years for males and 28.8 years for females. 3. The diagnosis of mandibular prognathism was made for 50 of the patients (90.9%). Sagittal split ramus osteotomy (SSRO) was performed on 37 (67.3%) cases. 4. The mean time of operation for SSRO was 2hr. 22min±1hr, and 11min and 4hr. 26min±1hr. 29min for the SSRO+Le Fort I osteotomy. 5. The mean blood loss was 130.9±157.9ml for SSRO and was 220.6±143.7ml for SSRO+Le Fort I osteotomy

Site-specific unglycosylation to improve crystallization of the metabotropic glutamate receptor 3 extracellular domain

The site-specific unglycosylated mutant of metabotropic glutamate receptor 3 extracellular domain has been overexpressed, purified, and crystallized. A complete data set has been collected to 2.35 Å resolution