The most prevalent genetic cause of ALS-FTD,C9orf72 synergizes the toxicity of ATXN2 intermediate polyglutamine repeats through the autophagy pathway

The most common genetic cause for amyotrophic lateral sclerosis and frontotemporal dementia (ALS-FTD) is repeat expansion of a hexanucleotide sequence (GGGGCC) within the C9orf72 genomic sequence. To elucidate the functional role of C9orf72 in disease pathogenesis, we identified certain molecular interactors of this factor. We determined that C9orf72 exists in a complex with SMCR8 and WDR41 and that this complex acts as a GDP/GTP exchange factor for RAB8 and RAB39, 2 RAB GTPases involved in macroautophagy/autophagy. Consequently, C9orf72 depletion in neuronal cultures leads to accumulation of unresolved aggregates of SQSTM1/p62 and phosphorylated TARDBP/TDP-43. However, C9orf72 reduction does not lead to major neuronal toxicity, suggesting that a second stress may be required to induce neuronal cell death. An intermediate size of polyglutamine repeats within ATXN2 is an important genetic modifier of ALS-FTD. We found that coexpression of intermediate polyglutamine repeats (30Q) of ATXN2 combined with C9orf72 depletion increases the aggregation of ATXN2 and neuronal toxicity. These results were confirmed in zebrafish embryos where partial C9orf72 knockdown along with intermediate (but not normal) repeat expansions in ATXN2 causes locomotion deficits and abnormal axonal projections from spinal motor neurons. These results demonstrate that C9orf72 plays an important role in the autophagy pathway while genetically interacting with another major genetic risk factor, ATXN2, to contribute to ALS-FTD pathogenesis.     

Angelman syndrome and severe infections in a patient with de novo 15q11.2–q13.1 deletion and maternally inherited 2q21.3 microdeletion

Angelman syndrome is a neurodevelopmental disorder characterized by mental retardation, severe speech disorder, facial dysmorphism, secondary microcephaly, ataxia, seizures, and abnormal behaviors such as easily provoked laughter. It is most frequently caused by a de novo maternal deletion of chromosome 15q11–q13 (about 70–90%), but can also be caused by paternal uniparental disomy of chromosome 15q11–q13 (3–7%), an imprinting defect (2–4%) or in mutations in the ubiquitin protein ligase E3A gene UBE3A mostly leading to frame shift mutation. In addition, for patients with overlapping clinical features (Angelman-like syndrome), mutations in methyl-CpG binding protein 2 gene MECP2 and cyclin-dependent kinase-like 5 gene CDKL5 as well as a microdeletion of 2q23.1 including the methyl-CpG binding domain protein 5 gene MBD5 have been described. Here, we describe a patient who carries a de novo 5 Mb-deletion of chromosome 15q11.2–q13.1 known to be associated with Angelman syndrome and a further, maternally inherited deletion 2q21.3 (~ 364 kb) of unknown significance. In addition to classic features of Angelman syndrome, she presented with severe infections in the first year of life, a symptom that has not been described in patients with Angelman syndrome. The 15q11.2–q13.1 deletion contains genes critical for Prader–Willi syndrome, the Angelman syndrome causing genes UBE3A and ATP10A/C, and several non-imprinted genes: GABRB3 and GABRA5 (both encoding subunits of GABA A receptor), GOLGA6L2, HERC2 and OCA2 (associated with oculocutaneous albinism II). The deletion 2q21.3 includes exons of the genes RAB3GAP1 (associated with Warburg Micro syndrome) and ZRANB3 (not disease-associated). Despite the normal phenotype of the mother, the relevance of the 2q21.3 microdeletion for the phenotype of the patient cannot be excluded, and further case reports will need to address this point.     

Prediction of structural consequences for disease causing variants in C21orf2 protein using computational approaches

Amyotrophic lateral sclerosis (ALS), a progressive motor-neurone disease, affects individuals usually aged between 50 and 70 years. C21orf2, recently identified as the new ALS susceptibility gene, harbours rare missense mutations that cause this fatal disease. We used bioinformatics and molecular modelling approaches to study specific ALS-associated mutations in C21orf2. Both native and mutant structures of the protein obtained from homology modelling were analysed in detail to gain insights into the potential impact of these mutations on the protein structure and its function. Our analyses reveal that more than 75% of the mutations are likely to be deleterious. These effects seem to carry through to mouse C21orf2 as well, indicating that mouse would make a viable animal model to study this ALS gene in detail.     

Genomic surveillance of Nevada patients revealed prevalence of unique SARS-CoV-2 variants bearing mutations in the RdRp gene

Patients with signs of COVID-19 were tested through diagnostic RT-PCR for SARS-CoV-2 using RNA extracted from the nasopharyngeal/nasal swabs.To determine the variants of SARS-CoV-2 circulating in the state of Nevada,specimens from 200 COVID-19 patients were sequenced through our robust sequencing platform,which enabled sequencing of SARS-CoV-2 from specimens with even very low viral loads,without the need of culture-based amplification.High genome coverage allowed the identification of single and multi-nucleotide variants in SARS-CoV-2 in the community and their phylogenetic relationships with other variants present during the same period of the outbreak.We report the occurrence of a novel mutation at 323aa (314aa of orf1b) of nsp12 (RNA-dependent RNA polymerase) changed to phenylalanine(F) from proline (P),in the first reported isolate of SARS-CoV-2,Wuhan-Hu-1.This 323F variant was present at a very high frequency in Northern Nevada.Structural modeling determined this mutation in the interface domain,which is important for the association of accessory proteins required for the polymerase.In conclusion,we report the introduction of specific SARS-CoV-2 variants at very high frequency in distinct geographic locations,which is important for understanding the evolution and circulation of SARS-CoV-2variants of public health importance,while it circulates in humans.     

C19orf66 Inhibits Japanese Encephalitis Virus Replication by Targeting -1 PRF and the NS3 Protein

Virologica Sinica - The Japanese encephalitis serogroup of the neurogenic Flavivirus has a specific feature that expresses a non-structural protein NS1′ produced through a programmed -1...     

人类新基因C17orf32的电子克隆和编码区序列RT-PCR验证

利用生物信息学与实验验证的技术路线,成功地克隆了人类新基因C17orf32的cDNA(GenBank登记号：AY074907和TPA: BK000260),发现C17orf32的完整开放阅读框架(ORF,31～657 bp）cDNA（627 bp）与人类假定基因LOC124919 ORF(25～807 bp)的25～651位只有一个碱基不同.经RT-PCR验证并cDNA测序、人类表达序列标签(EST)数据库的BLAST检索和基因组成规律分析三方面的结果,均支持C17orf32的序列,而不支持LOC124919的编码序列.C17orf32基因组序列全长4.610 kb,含有6个外显子和5个内含子,cDNA序列全长1 679 bp, ORF横跨全部6个外显子.该基因ORF翻译起始处符合Kozak规则,ORF起始码上游同一相位有终止码,ORF后有2个加尾信号和PolyA尾.C17orf32基因的成功克隆表明,NCBI GENOME Annotation Project在2001年12月预测的人类假定蛋白XP-058865编码基因LOC124919的模式参考序列XM-058865中存在偏差,即在C17orf32基因cDNA的406与407位碱基之间错误插入一个碱基G, 从而导致在插入位点后,ORF编码125位氨基酸以后蛋白质序列的改变,出现260个氨基酸的多肽.因此,应慎重看待计算机注释的人类基因组编码序列.建立的技术路线有助于发现更多新的人类功能基因.     

Removal of RTF2 from Stalled Replisomes Promotes Maintenance of Genome Integrity

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Organization and assembly of the TRAPPII complex

Current models suggest that TRAPP tethering complexes exist in two forms. Whereas the seven-subunit TRAPPI complex mediates ER-to-Golgi transport, TRAPPII contains three additional subunits (Trs65, Trs120 and Trs130) and is required for distinct tethering events at Golgi membranes. It is not clear how TRAPPII assembly is regulated. Here, we show that Tca17 is a fourth TRAPPII-specific component, and that Trs65 and Tca17 interact with distinct domains of Trs130 and make different contributions to complex assembly. Whereas Tca17 promotes the stable association of TRAPPII-specific subunits with the core complex, Trs65 stabilizes TRAPPII in an oligomeric form. We show that Trs85, which was previously reported to be a subunit of both TRAPPI and TRAPPII, is not associated with the TRAPPII complex in yeast. However, we find that proteins related to Trs85, Trs65 and Tca17 are part of the same TRAPP complex in mammalian cells. These findings have implications for models of TRAPP complex formation and suggest that TRAPP complexes may be organized differently in yeast and mammals.