Case Report: A novel de novo variant of COL1A1 in fetal genetic osteogenesis imperfecta.

Objective: Osteogenesis imperfecta (OI) is a rare genetic disorder. Clinical severity is heterogeneous. The purpose of this study was to investigate the genetic characteristics of a fetus with OI by whole exome sequencing (WES) and identify the cause of the disease. Methods: In this study, a fetus with osteogenic dysplasia was referred to our hospital. DNA was extracted from the aborted fetal tissue and peripheral blood of the parents. To identify the pathogenic genes, we conducted the trio-WES using DNA. A de novo variant in the COL1A1 gene is suspected to be the cause of the OI phenotype. We used Sanger sequencing for validation and various bioinformatics methods (such as SIFT, PolyPhen2, Mutation Taster, conservative analysis, SWISS Model, glycosylation site prediction, and I-Mutant 2.0) for analysis. Results: Both WES and Sanger sequencing identified a novel de novo variant of COL1A1 (c. 1309G>A, p. Gly437Ser) in a fetus with OI. Bioinformatic analysis showed that the affected residue, p. Gly437, was highly conserved in multiple species and predicted that the variant was deleterious and may have an impact on protein function. This variant is present in highly conserved glycine residues of Gly-X-Y sequence repeats of the triple helical region of the collagen type I α chain, which may be the cause of OI. Conclusion: This study revealed that the c.1309G>A (p. Gly437Ser) variant in the COL1A1 gene may be the genetic cause of fetal OI in this case. The discovery of this variant enriched the variation spectrum of OI. WES improves the accurate diagnosis of fetal OI, and doctors can provide patients with appropriate genetic counseling.

A Pyroptosis-Related Gene Panel for Predicting the Prognosis and Immune Microenvironment of Cervical Cancer.

Cervical cancer (CC) is one of the most common malignant tumors of the female reproductive system. And the immune system disorder in patients results in an increasing incidence rate and mortality rate. Pyroptosis is an immune system-related programmed cell death pathway that produces systemic inflammation by releasing pro-inflammatory intracellular components. However, the diagnostic significance of pyroptosis-related genes (PRGs) in CC is still unclear. Therefore, we identified 52 PRGs from the TCGA database and screened three Differentially Expressed Pyroptosis-Related Genes (DEPRGs) in the prognosis of cervical cancer: CHMP4C, GZMB, TNF. The least absolute shrinkage and selection operator (LASSO) regression analysis and multivariate COX regression analysis were then used to construct a gene panel based on the three prognostic DEPRGs. The patients were divided into high-and low-risk groups based on the median risk score of the panel. According to the Kaplan-Meier curve, there was a substantial difference in survival rates between the two groups, with the high-risk group's survival rate being significantly lower than the low-risk group's. The PCA and t-SNE analyses revealed that the panel was able to differentiate patients into high-and low-risk groups. The area under the ROC curve (AUC) shows that the prognostic panel has high sensitivity and specificity. The risk score could then be employed as an independent prognostic factor using univariate and multivariate COX regression analyses paired with clinical data. The analyses of GO and KEGG functional enrichment of differentially expressed genes (DEGs) in the high-and low-risk groups revealed that these genes were primarily engaged in immune response and inflammatory cell chemotaxis. To illustrate immune cell infiltration in CC patients further, we used ssGSEA to compare immune-related cells and immune pathway activation between the high-and low-risk groups. The link between three prognostic DEPRGs and immune-related cells was still being discussed after evaluating immune cell infiltration in the TCGA cohort with "CIBERSORT." In addition, the GEPIA database and qRT-PCR analysis were used to verify the expression levels of prognostic DEPRGs. In conclusion, PRGs are critical in tumor immunity and can be utilized to predict the prognosis of CC.

YTHDF2 inhibit the tumorigenicity of endometrial cancer via downregulating the expression of IRS1 methylated with m6A.

RNA epigenetic modification take part in many biology processes, and the N6-methyladenosine (m6A) methylation of specific mRNAs in endometrial cancer (EC) tissues play a key role in regulating the tumorigenicity of EC, but the specific mechanism still unknown and need to be investigated in the future. Here, we found that m6A reader protein YTHDF2 expression was significantly upregulated in EC compare to tumor adjacent tissues, YTHDF2 was then identified to inhibit the proliferation and invasion of EC cell lines. Mechanistically, the m6A reader YTHDF2 bind the methylation sites of target transcripts IRS1 and promoted IRS1 mRNA degradation, consequently inhibiting the expression of IRS1 and inhibiting IRS1/AKT signaling pathway, finally inhibit the tumorigenicity of EC. Thus, we demonstrated that YTHDF2 inhibited the proliferation and invasion of EC via inhibiting IRS1 expression in m6A epigenetic way, which suggests a potential therapeutic target for EC.

[Progress in epigenetic modification of mRNA and the function of m6A modification].

Messenger RNA (mRNA) can be modified by more than 100 chemical modifications. Among these modifications, N6-methyladenosine (m6A) is one of the most prevalent modifications. During the processes of cells differentiation, embryo development or stress, m6A can be modified on key mRNAs and regulate the progress of cells through modulating mRNA metabolism and translation. Other mRNA modifications, including N1-methyladenosine (m¹A), 5-methylcytosine (m5C) and pseudouridine, together with m6A form the epitranscriptome of mRNA that accurately modulate the mRNA translation. Here we review the types and characteristic of mRNA epigenetic modifications, especially the recent progresses of the function of m6A, we also expect the main research direction of m6A epigenetic modification in the future.

The RNA helicase DDX46 inhibits innate immunity by entrapping m6A-demethylated antiviral transcripts in the nucleus.

DEAD-box (DDX) helicases are vital for the recognition of RNA and metabolism and are critical for the initiation of antiviral innate immunity. Modification of RNA is involved in many biological processes; however, its role in antiviral innate immunity has remained unclear. Here we found that nuclear DDX member DDX46 inhibited the production of type I interferons after viral infection. DDX46 bound Mavs, Traf3 and Traf6 transcripts (which encode signaling molecules involved in antiviral responses) via their conserved CCGGUU element. After viral infection, DDX46 recruited ALKBH5, an 'eraser' of the RNA modification N6-methyladenosine (m6A), via DDX46's DEAD helicase domain to demethylate those m6A-modified antiviral transcripts. It consequently enforced their retention in the nucleus and therefore prevented their translation and inhibited interferon production. DDX46 also suppressed antiviral innate immunity in vivo. Thus, DDX46 inhibits antiviral innate responses by entrapping selected antiviral transcripts in the nucleus by erasing their m6A modification, a modification normally required for export from the nucleus and translation.

Siglec1 suppresses antiviral innate immune response by inducing TBK1 degradation via the ubiquitin ligase TRIM27.

Type I interferon (IFN) production plays pivotal roles in host antiviral innate immune responses, but an excessive production of type I IFN leads to the development of immunopathological conditions. Investigations on the regulatory mechanisms underlying host type I IFN production are currently of great interest. Here, we found that the expression of lectin family member Siglec1 was upregulated by viral infection in macrophages, which was dependent on the IFN/JAK/STAT1 signaling pathway. Siglec1 was found to negatively regulate viral infection-triggered type I IFN production. Mechanistically, Siglec1 associates with DAP12 to recruit and activate the scaffolding function of SHP2; SHP2 then recruits E3 ubiquitin ligase TRIM27, which induces TBK1 degradation via K48-linked ubiquitination at Lys251 and Lys372. Therefore, viral infection-induced upregulation of Siglec1 feedback loop inhibits type I IFN production and suppresses antiviral innate immune responses. Our study outlines a novel mechanism of negative regulation of type I IFN production, which may help virus to escape immune elimination.

MicroRNA-452 promotes tumorigenesis in hepatocellular carcinoma by targeting cyclin-dependent kinase inhibitor 1B.

Dysregulation of miR-452 has been observed in many tumors, but its biological function in hepatocellular carcinoma (HCC) is still unknown. Our results showed that miR-452 expression is significantly increased in HCC tissues and HCC cell lines. We also found that overexpression of miR-452 dramatically accelerated proliferation, induced cell cycle from G1 to S transition, and blocked apoptosis of HCC cells. Migration and matrigel invasion assays indicated that miR-452 significantly promotes HepG2 and QGY-7703 cells migration and invasion in vitro. Further studies showed that miR-452 directly targets the 3'-untranslated region of cyclin-dependent kinase inhibitor 1B (CDKN1B), ectopic miR-452 expression suppressed CDKN1B expression on mRNA and protein level. Silencing CDKN1B by small interfering RNA resembled the phenotype resulting from ectopic miR-452 expression. This study provides new insights into the potential molecular mechanisms that miRNA-452 contributed to HCC.

A novel method for isolation of membrane proteins: a baculovirus surface display system.

We have developed a novel baculovirus surface display (BVSD) system for the isolation of membrane proteins. We expressed a reporter gene that encoded hemagglutinin gene fused in frame with the signal peptide and transmembrane domain of the baculovirus gp64 protein, which is displayed on the surface of BmNPV virions. The expression of this fusion protein on the virion envelope allowed us to develop two methods for isolating membrane proteins. In the first method, we isolated proteins directly from the envelope of budding BmNPV virions. In the second method, we isolated proteins from cellular membranes that had disintegrated due to viral egress. We isolated 6756 proteins. Of these, 1883 have sequence similarities to membrane proteins and 1550 proteins are homologous to known membrane proteins. This study indicates that membrane proteins can be effectively isolated using our BVSD system. Using an analogous method, membrane proteins can be isolated from other eukaryotic organisms, including human beings, by employing a host cell-specific budding virus.