Genome-scale CRISPR screen identifies TMEM41B as a multi-function host factor required for coronavirus replication

Emerging coronaviruses (CoVs) pose a severe threat to human and animal health worldwide. To identify host factors required for CoV infection, we used α-CoV transmissible gastroenteritis virus (TGEV) as a model for genome-scale CRISPR knockout (KO) screening. Transmembrane protein 41B (TMEM41B) was found to be a bona fide host factor involved in infection by CoV and three additional virus families. We found that TMEM41B is critical for the internalization and early-stage replication of TGEV. Notably, our results also showed that cells lacking TMEM41B are unable to form the double-membrane vesicles necessary for TGEV replication, indicating that TMEM41B contributes to the formation of CoV replication organelles. Lastly, our data from a mouse infection model showed that the KO of this factor can strongly inhibit viral infection and delay the progression of a CoV disease. Our study revealed that targeting TMEM41B is a highly promising approach for the development of broad-spectrum anti-viral therapeutics.     

VPS35 D620N knockin mice recapitulate cardinal features of Parkinson’s disease

D620N mutation in the vacuolar protein sorting 35 ortholog (VPS35) gene causes late‐onset, autosomal dominant familial Parkinson''s disease (PD) and contributes to idiopathic PD. However, how D620N mutation leads to PD‐related deficits in vivo remains unclear. In the present study, we thoroughly characterized the biochemical, pathological, and behavioral changes of a VPS35 D620N knockin (KI) mouse model with chronic aging. We reported that this VPS35 D620N KI model recapitulated a spectrum of cardinal features of PD at 14 months of age which included age‐dependent progressive motor deficits, significant changes in the levels of dopamine (DA) and DA metabolites in the striatum, and robust neurodegeneration of the DA neurons in the SNpc and DA terminals in the striatum, accompanied by increased neuroinflammation, and accumulation and aggregation of α‐synuclein in DA neurons. Mechanistically, D620N mutation induced mitochondrial fragmentation and dysfunction in aged mice likely through enhanced VPS35‐DLP1 interaction and increased turnover of mitochondrial DLP1 complexes in vivo. Finally, the VPS35 D620N KI mice displayed greater susceptibility to MPTP‐mediated degeneration of nigrostriatal pathway, indicating that VPS35 D620N mutation increased vulnerability of DA neurons to environmental toxins. Overall, this VPS35 D620N KI mouse model provides a powerful tool for future disease modeling and pharmacological studies of PD. Our data support the involvement of VPS35 in the development of α‐synuclein pathology in vivo and revealed the important role of mitochondrial fragmentation/dysfunction in the pathogenesis of VPS35 D620N mutation‐associated PD in vivo.     

SMYD1, an SRF-Interacting Partner,Is Involved in Angiogenesis

Previous studies have demonstrated that Smyd1 plays a critical role in cardiomyocyte differentiation, cardiac morphogenesis and myofibril organization. In this study, we uncovered a novel function of Smyd1 in the regulation of endothelial cells (ECs). Our data showed that Smyd1 is expressed in vascular endothelial cells, and knockdown of SMYD1 in endothelial cells impairs EC migration and tube formation. Furthermore, Co-IP and GST pull-down assays demonstrated that SMYD1 is associated with the Serum Response Factor (SRF). EMSA assays further showed that SMYD1 forms a complex with SRF and enhances SRF DNA binding activity. Our studies indicate that SMYD1 serves as an SRF-interacting protein, enhances SRF DNA binding activity, and is required for EC migration and tube formation to regulate angiogenesis.     

Amyloid-beta42 interacts mainly with insoluble prion protein in the Alzheimer brain

The prion protein (PrP) is best known for its association with prion diseases. However, a controversial new role for PrP in Alzheimer disease (AD) has recently emerged. In vitro studies and mouse models of AD suggest that PrP may be involved in AD pathogenesis through a highly specific interaction with amyloid-β (Aβ42) oligomers. Immobilized recombinant human PrP (huPrP) also exhibited high affinity and specificity for Aβ42 oligomers. Here we report the novel finding that aggregated forms of huPrP and Aβ42 are co-purified from AD brain extracts. Moreover, an anti-PrP antibody and an agent that specifically binds to insoluble PrP (iPrP) co-precipitate insoluble Aβ from human AD brain. Finally, using peptide membrane arrays of 99 13-mer peptides that span the entire sequence of mature huPrP, two distinct types of Aβ binding sites on huPrP are identified in vitro. One specifically binds to Aβ42 and the other binds to both Aβ42 and Aβ40. Notably, Aβ42-specific binding sites are localized predominantly in the octapeptide repeat region, whereas sites that bind both Aβ40 and Aβ42 are mainly in the extreme N-terminal or C-terminal domains of PrP. Our study suggests that iPrP is the major PrP species that interacts with insoluble Aβ42 in vivo. Although this work indicated the interaction of Aβ42 with huPrP in the AD brain, the pathophysiological relevance of the iPrP/Aβ42 interaction remains to be established.     

Delayed re-epithelialization in Ppm1a gene-deficient mice is mediated by enhanced activation of Smad2

Protein phosphatase magnesium-dependent 1A (PPM1A), a protein serine/threonine phosphatase, controls several signal pathways through cleavage of phosphate from its substrates. However, the in vivo function of Ppm1a in mammals remains unknown. Here we reported that mice lacking Ppm1a developed normally but were impaired in re-epithelialization process during cutaneous wound healing. Specifically, complete or keratinocyte-specific deletion of Ppm1a led to delayed re-epithelialization with reduced keratinocyte migration upon wounding. We showed that this effect was the result of an increase in Smad2/3 phosphorylation in keratinocytes. Keratinocyte-specific Smad2 deficient mice displayed accelerated re-epithelialization with enhanced keratinocyte migration. Importantly, Smad2 and Ppm1a double mutant mice also exhibited accelerated re-epithelialization, demonstrating that the effect of Ppm1a on promoting re-epithelialization is mediated by Smad2 signaling. Furthermore, the decreased expression of specific integrins and matrix metalloproteinases (MMPs) may contribute to the retarded re-epithelialization in Ppm1a mutant mice. These data indicate that Ppm1a, through suppressing Smad2 signaling, plays a critical role in re-epithelialization during wound healing.     

贵州麻阳河国家级自然保护区红外相机鸟兽监测

为进一步查清贵州麻阳河国家级自然保护区鸟兽多样性, 丰富生物编目, 我们于2018年7月至2019年8月利用红外相机进行公里网格全境布设监测。共记录兽类5目10科18属20种、鸟类7目18科34属42种, 其中新增保护区记录11种, 记录国家I级重点保护野生动物2种, 分别是黑叶猴(Trachypithecus francoisi)和白颈长尾雉(Syrmaticus ellioti), 国家II级重点保护野生动物大灵猫(Viverra zibetha)、白冠长尾雉(Syrmaticus reevesii)等7种。相对多度指数计算结果表明, 小麂(Muntiacus reevesi)、猪獾(Arctonyx collaris)和野猪(Sus scrofa)是该区域内常见兽类, 而地栖雉类则以红腹锦鸡(Chrysolophus pictus)和灰胸竹鸡(Bambusicola thoracicus)为主。分时段的相对多度指标表明, 小麂在6:00-15:00和17:00-21:00两个时段均保持活跃, 猪獾则偏好5:00-6:00和19:00-23:00活动, 野猪在6:00-7:00最为活跃, 红腹锦鸡活动高峰在12:00-13:00, 而灰胸竹鸡的活动高峰分别为14:00-15:00和16:00-17:00。在物种丰度上, 单个相机位点的平均拍摄物种数显示, 在缓冲区、灌丛及针阔混交林以及800-1,200 m海拔段上物种较多。监测结果有利于进一步掌握此区域的动物多样性资源并促进资源的保护与管理。     

DLP1-dependent mitochondrial fragmentation mediates 1-methyl-4-phenylpyridinium toxicity in neurons: implications for Parkinson's disease

Selective degeneration of nigrostriatal dopaminergic neurons in Parkinson’s disease (PD) can be modeled by the administration of the neurotoxin 1‐methyl‐4‐phenylpyridinium (MPP⁺). Because abnormal mitochondrial dynamics are increasingly implicated in the pathogenesis of PD, in this study, we investigated the effect of MPP⁺ on mitochondrial dynamics and assessed temporal and causal relationship with other toxic effects induced by MPP⁺ in neuronal cells. In SH‐SY5Y cells, MPP⁺ causes a rapid increase in mitochondrial fragmentation followed by a second wave of increase in mitochondrial fragmentation, along with increased DLP1 expression and mitochondrial translocation. Genetic inactivation of DLP1 completely blocks MPP⁺‐induced mitochondrial fragmentation. Notably, this approach partially rescues MPP⁺‐induced decline in ATP levels and ATP/ADP ratio and increased [Ca²⁺]_i and almost completely prevents increased reactive oxygen species production, loss of mitochondrial membrane potential, enhanced autophagy and cell death, suggesting that mitochondria fragmentation is an upstream event that mediates MPP⁺‐induced toxicity. On the other hand, thiol antioxidant N‐acetylcysteine or glutamate receptor antagonist D‐AP5 also partially alleviates MPP⁺‐induced mitochondrial fragmentation, suggesting a vicious spiral of events contributes to MPP⁺‐induced toxicity. We further validated our findings in primary rat midbrain dopaminergic neurons that 0.5 μm MPP⁺ induced mitochondrial fragmentation only in tyrosine hydroxylase (TH)‐positive dopaminergic neurons in a similar pattern to that in SH‐SY5Y cells but had no effects on these mitochondrial parameters in TH‐negative neurons. Overall, these findings suggest that DLP1‐dependent mitochondrial fragmentation plays a crucial role in mediating MPP⁺‐induced mitochondria abnormalities and cellular dysfunction and may represent a novel therapeutic target for PD.     

不同种源樟树叶片形态特征及生长差异分析

为了解不同种源樟树叶片形态特征和生长差异,该文以30个种源樟树为研究对象,对其叶长、叶宽、叶柄长、周长、叶面积、长宽比、形态因子、株高、地径等指标进行测定和差异性分析.结果表明:(1)30个种源间叶片性状的变异系数为3.88％～16.14％,显示不同种源樟树叶片形态特征存在显著差异;叶长、叶宽、叶柄长、周长、面积、叶厚...