MedNexus
2020年 · 第03卷第03期
MedNexus
Alternative splicing plays a pivotal role in the posttranscriptional regulation of gene expression, contributing to the generation of proteome diversity. Autophagy is a conserved cellular machinery governing degradation and recycling of long-lived or damaged proteins and organelles. However, there is limited knowledge of the roles of alternative splicing in autophagy, in particular mitochondrial selective autophagy, termed mitophagy. Emerging evidence suggests autophagy-related proteins (Atg), key molecules in autophagy process, are involved. This review highlights recent advances in the understanding of mechanisms by which alternative splicing affects the functions of ATG genes including BECN1, ATG5, ATG16L1, and Bim genes, and thus manipulates autophagy levels in various diseases. This review found that the effects of splicing of ATG genes generally result in inhibiting autophagy. However, very few of the many autophagy associated proteins have been studied. More research into the transcriptional and post-transcriptional regulation of splicing factors will be necessary to understand their roles in pathological conditions associated with autophagy and mitophagy.
Genome editing serves as a powerful approach to interrogate the functions of both coding and noncoding sequences. In particular, clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR associated protein 9 (Cas9) system-based editing tools have revolutionized the way we study genome function in mammalian cells, and are being widely used for interrogating critical genes and DNA elements essential for many biological processes. Here, we review CRISPR/Cas9-based genetic tools with an emphasis on CRISPR-mediated high throughput genetic screens in the mammalian genome.
Congenital heart disease (CHD) is the most common birth defect worldwide. In recent years, the widespread application of innovative molecular diagnostic technologies in clinical scenarios has obviously increased the molecular diagnostic yields of CHD, providing evidence-based guidance for medical decision-making. These molecular diagnostic technologies include chromosome microarray analysis, targeted sequencing, exome sequencing, and genome sequencing. Furthermore, high-throughput sequencing technology has performed excellently in the clinical molecular diagnosis of CHD. This review provides an overview of the current technology and applications in the molecular diagnosis of CHD. The unmet issues and future directions in adapting novel genomic testing technologies to the molecular diagnosis of CHD in clinical settings are also addressed.
Despite overwhelming evidence from large randomized clinical trials supporting a clear benefit of low-density lipoprotein cholesterol (LDL-C) lowering therapy on the primary and secondary prevention of atherosclerotic cardiovascular disease, data from epidemiological and clinical observations demonstrated an increased incidence of hemorrhagic stroke in patients with low LDL-C exposure (<70 mg/dL), especially among East Asians. Meanwhile, emerging studies have reported a paradoxical phenomenon in which hypercholesterolemia is associated with better short-term outcomes in acute coronary syndrome patients, the "lipid paradox." The underlying mechanism for these two closely connected clinical observations is not clear. This review aimed to summarize the evolution and clinical implications of these two low LDL-C related concepts, and proposed a "double-hit" hypothesis that may help explain these phenomena. It is worth noting that in the era of increasing use of high-intensity LDL-C lowering and dual antiplatelet strategies in atherosclerotic cardiovascular disease in patients receiving percutaneous coronary intervention, balancing the risk of thrombosis with bleeding complication should be a priority in clinical practice. Our hypothesis may raise clinicians’ awareness to identify potential high risk patients with low LDL-C (<70 mg/dL), especially among East Asians.
In contrast to the most commonly reported forms of maturity-onset diabetes of the young (MODY), including MODY2, MODY3 and MODY5, MODY6 is a relatively rare subtype. To investigate whether NEUROD1 is responsible for MODY in Chinese individuals, we screened its mutations in MODY pedigrees and explored the potential pathogenic mechanisms.
Polymerase chain reaction direct sequencing was performed to screen NEUROD1 mutations in 32 Chinese MODY probands who were negative for the GCK/MODY2, HNF1A/MODY3 and HNF1B/MODY5 genes in this observational study. In addition, we enrolled 201 unrelated, non-diabetic control subjects of Han Chinese descent. The functional significance of newly identified mutations was analyzed using clinical phenotype, pathophysiology and three-dimensional structure studies. This study was approved by the Institutional Review Board of Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, China (approval No. YS-2017-83) on March 3, 2017.
E59Q (c.175 G>C, p.Glu59Gln), a heterozygous missense mutation in the NEUROD1 gene, was identified in one family with MODY. The Glu59 residue in NeuroD1 is highly conserved across mammalian species. Four diabetic patients carrying the mutation (a proband and her son, brother and sister) were lean, with a body mass index of 20.9 (20.3-21.2) kg/m2. Compared with their unaffected relatives (n= 4), E59Q carriers (n= 4) had significantly decreased ratios of fasting and 2-hour insulin to plasma glucose (both fasting plasma insulin/fasting plasma glucose and 2-hour postprandial plasma insulin/2-hour postprandial plasma glucose, P < 0.005). The proband’s father had an E59Q mutation and normal glucose tolerance, which suggested non-penetrance. The E59Q mutation was not detected in other probands or in the 201 control subjects with normal glucose tolerance. Two salt-bridge bonds of Glu59 were disrupted at the Q59 mutation site.
The NEUROD1-E59Q mutation changed the molecular conformation of the N-terminal in NeuroD1, which may decrease binding of the E59Q mutant to the insulin promoter and insulin gene transcription activity, therefore causing the MODY6 subtype with defective insulin secretion.
The immune system is involved in the pathogenesis of schizophrenia; here, we aimed to explore the relationship of cytotoxic T lymphocyte antigen 4 (CTLA4) with schizophrenia.
CTLA4 gene structure was first analyzed, and then rs231779, rs733618, rs231775 and rs3087243 were selected as tag single nucleotide polymorphisms for the linkage disequilibrium blocks in CTLA4 in the Chinese Han population to study expression quantitative trait loci of CTLA4 gene in normal brain tissue. Additionally, membrane CTLA4 (mCTLA4) and soluble CTLA4 (sCTLA4) mRNA expression levels were evaluated in peripheral blood mononuclear cells from 65 first-episode schizophrenia patients and 61 healthy controls. This study was approved by the Bioethics Committee of corresponding research institutes (approval No. 20150016) on March 6, 2015 and the principles of the Declaration of Helsinki.
After applying Bonferroni correction to the P values, only the minor C allele of rs733618 was significantly associated with increased expression of total CTLA4 (PBonf.= 0.019), but not mCTLA4 (PBonf. = 0.115), in the hippocampus. The sCTLA4 expression was significantly decreased in the peripheral blood mononuclear cells of schizophrenia patients compared with healthy controls, while mCTLA4 was not.
These results suggest that the soluble form of CTLA4 may be associated with schizophrenia and that lower sCTLA4 expression may increase the risk of developing schizophrenia.
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