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

Different Levels of Ovine Interferon-t Gene Expressions Are Regulated Through the Short Promoter Region Including Ets-2 Binding Site

Regulation of interferon-t (IFNt) production, a conceptus secretory protein implicated in the process of maternal recognition of pregnancy, has not been fully elucidated. Among more than 10 ovine IFNt (oIFNt) gene sequences characterized, approximately 75% of oIFNt transcripts expressed in utero is derived from oIFNt-o10 gene and amounts of transcripts from other oIFNt genes such as oIFNt-o8 or oIFNt-o2 are minimal. It was hypothesized that the variation in expression levels exhibited by oIFNt-o10 and oIFNt-o8/-o2 genes was due to differences in the proximal promoter regions of these oIFNt genes. To test this hypothesis, transient transfection experiments with human choriocarcinoma JEG3 cells were executed with deleted and/or mutated 50-upstream regions of these oIFNt genes attached to the chloramphenicol acetyltransferase (CAT) reporter gene. Because only the Ets-2 binding site located in the oIFNt-o10 gene appeared to differentiate the expression levels of these constructs, the 6 base pair (bp) Ets-2 sequence from the oIFNt-o10 gene inserted into the oIFNt-o8/-o2 gene-reporter construct was examined. The insertion of this Ets-2 binding site into the oIFNt-o8/o2-reporter construct failed to increase the degree of transactivation. Rather than this 6 bp sequence, a 22 bp sequence of the proximal promoter region, including the Ets-2 binding site, of the oIFNt-o10 gene was required for oIFNt-o8/-o2-reporter transactivation. By electrophoretic mobility shift assay (EMSA), nuclear protein(s) bound to this 22 bp from the oIFNt-o10 and oIFNt-o8/o2 genes differed. These results suggest that the short promoter region including the Ets-2 binding site, not the Ets-2 binding region itself, may determine different levels of oIFNt gene expressions seen in utero

Investigation of Metabolism of Exogenous Glucose at the Early Stage and Onset of Diabetes Mellitus in Otsuka Long-Evans Tokushima Fatty Rats Using [1, 2, 3-¹³C]Glucose Breath Tests

<div><p>This study aimed to evaluate changes in glucose metabolism at the early stage and onset of diabetes in Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Specifically, after the oral administration of [1, 2, 3-¹³C]glucose, the levels of exhaled ¹³CO₂, which most likely originated from pyruvate decarboxylation and tricarboxylic acid, were measured. Eight OLETF rats and eight control rats (Long-Evans Tokushima Otsuka [LETO]) were administered ¹³C-glucose. Three types of ¹³C-glucose breath tests were performed thrice in each period at 2-week intervals. [3-¹³C]glucose results in a ¹³C isotope at position 1 in the pyruvate molecule, which provides ¹³CO₂. The ¹³C at carbons 1 and 2 of glucose is converted to ¹³C at carbons 2 and 1 of acetate, respectively, which produce ¹³CO₂. Based on metabolic differences of the labeled sites, glucose metabolism was evaluated using the results of three breath tests. The increase in ¹³CO₂ excretion in OLETF rats was delayed in all three breath tests compared to that in control rats, suggesting that OLETF rats had a lower glucose metabolism than control rats. In addition, overall glucose metabolism increased with age in both groups. The utilization of [2-¹³C]glucose was suppressed in OLETF rats at 6–12 weeks of age, but they showed higher [3-¹³C]glucose oxidation than control rats at 22–25 weeks of age. In the [1-¹³C]glucose breath test, no significant differences in the area under the curve until 180 minutes (AUC₁₈₀) were observed between OLETF and LETO rats of any age. Glucose metabolism kinetics were different between the age groups and two groups of rats; however, these differences were not significant based on the overall AUC₁₈₀ of [1-¹³C]glucose. We conclude that breath ¹³CO₂ excretion is reduced in OLETF rats at the primary stage of prediabetes, indicating differences in glucose oxidation kinetics between OLETF and LETO rats.</p></div

Results of [1-¹³C]glucose breath tests.

<p>(A) Changes in expired ¹³CO₂ levels after the oral administration of 100 mg/kg of [1-¹³C]glucose in OLETF rats at 5–11weeks, 14–17 weeks, and 20–23 weeks of age. (B) Changes in expired ¹³CO₂ levels after the oral administration of 100 mg/kg of [1-¹³C]glucose in LETO rats at 5–11 weeks, 14–17 weeks, and 20–23 weeks of age. Data are represented as mean ± SD.</p

[2-¹³C]glucose breath test between OLETF and LETO rats.

<p>Comparison of ¹³CO₂ excretion curves after the oral administration of 100 mg/kg of [2-¹³C]glucose between OLETF and LETO rats at 6–12 weeks (A), 15–18 weeks (B), and 21–24 weeks (C) of age. Data are represented as mean ± SD.</p

Tmax obtained from the three types of ¹³C-glucose breath tests for each age group.

<p>Tmax obtained from the three types of ¹³C-glucose breath tests for each age group.</p

Peak values obtained from the three types of ¹³C-glucose breath tests for each age group.

<p>Peak values obtained from the three types of ¹³C-glucose breath tests for each age group.</p