Biology subjects

Shan, S.

Publications and source records attributed to Shan, S..

26 records · Page 2Linked to original sources

bioRxiv2020

Potent human neutralizing antibodies elicited by SARS-CoV-2 infection

The pandemic caused by emerging coronavirus SARS-CoV-2 presents a serious global public health emergency in urgent need of prophylactic and therapeutic interventions. SARS-CoV-2 cellular entry depends on binding between the viral Spike protein receptor-binding domain (RBD) and the angiotensin converting enzyme 2 (ACE2) target cell receptor. Here, we report on the isolation and characterization of 206 RBD-specific monoclonal antibodies (mAbs) derived from single B cells of eight SARS-CoV-2 infected individuals. These mAbs come from diverse families of antibody heavy and light chains without apparent enrichment for particular families in the repertoire. In samples from one patient selected for further analyses, we found coexistence of germline and germline divergent clones. Both clone types demonstrated impressive binding and neutralizing activity against pseudovirus and live SARS-CoV-2. However, the antibody neutralizing potency is determined by competition with ACE2 receptor for RBD binding. Surprisingly, none of the SARS-CoV-2 antibodies nor the infected plasma cross-reacted with RBDs from either SARS-CoV or MERS-CoV although substantial plasma cross-reactivity to the trimeric Spike proteins from SARS-CoV and MERS-CoV was found. These results suggest that antibody response to RBDs is viral species-specific while that cross-recognition target regions outside the RBD. The specificity and neutralizing characteristics of this plasma cross-reactivity requires further investigation. Nevertheless, the diverse and potent neutralizing antibodies identified here are promising candidates for prophylactic and therapeutic SARS-CoV-2 interventions.

immunology↗

bioRxiv2020

Crystal structure of the 2019-nCoV spike receptor-binding domain bound with the ACE2 receptor

A novel and highly pathogenic coronavirus (2019-nCoV) has caused an outbreak in Wuhan city, Hubei province of China since December 2019, and soon spread nationwide and spilled over to other countries around the world. To better understand the initial step of infection at atomic-level, we determined the crystal structure of the 2019-nCoV spike receptor-binding domain (RBD) bound with the cell receptor ACE2 at 2.45 [A] resolution. The overall ACE2-binding mode of the 2019-nCoV RBD is nearly identical to that of the SARS-CoV RBD, which also utilizes ACE2 as the cell receptor. Structural analysis identified residues in 2019-nCoV RBD critical for ACE2 binding, and majority of which are either highly conserved or shared similar side chain properties with those in the SARS-CoV RBD. Such similarity in structure and sequence strongly argue for a convergent evolution between 2019-nCoV and SARS-CoV RBD for improved binding to ACE2 despite of being segregated in different genetic lineages in the betacoronavirus genus. The epitopes of two SARS-CoV antibodies targeting the RBD are also analyzed with the 2019-nCoV RBD, providing insights into future identification of cross-reactive antibodies.

biophysics↗

bioRxiv2018

Neocortical layer 4 in adult mouse differs in major cell types and circuit organization between primary sensory areas

Layer 4 (L4) of mammalian neocortex plays a crucial role in cortical information processing, yet a complete census of its cell types and connectivity remains elusive. Using whole-cell recordings with morphological recovery, we identified one major excitatory and seven inhibitory types of neurons in L4 of adult mouse visual cortex (V1). Nearly all excitatory neurons were pyramidal and almost all Somatostatin-positive (SOM+) neurons were Martinotti cells. In contrast, in somatosensory cortex (S1), excitatory cells were mostly stellate and SOM+ cells were non-Martinotti. These morphologically distinct SOM+ interneurons correspond to different transcriptomic cell types and are differentially integrated into the local circuit with only S1 cells receiving local excitatory input. Our results challenge the classical view of a canonical microcircuit repeated through the neocortex. Instead we propose that cell-type specific circuit motifs, such as the Martinotti/pyramidal pair, are optionally used across the cortex as building blocks to assemble cortical circuits.

neuroscience↗

bioRxiv2018

Christmas disease in a Hovawart family resembling human hemophilia B Leyden is caused by a single nucleotide deletion in a highly conserved transcription factor binding site of the F9 gene promoter

Hemophilia B is a classical monogenic X-chromosomal recessively transmitted bleeding disorder caused by genetic variants within the coagulation factor IX gene (F9). Although hemophilia B has been described in 28 dog breeds and four mixed-breed dogs hitherto, it has not yet been reported in the Hovawart. Here we describe the identification of a Hovawart family transmitting typical signs of an X-linked bleeding disorder. Five males had been reported to suffer from recurrent hemorrhagic episodes, four of them had to be euthanized finally and one died due to severe blood loss. A blood sample of one of these males with only 2% of the normal concentration of plasma factor IX (FIX) together with samples of seven relatives including the mother and grandmother were provided for further analysis. Next generation sequencing of DNA of the mother and grandmother revealed a single nucleotide deletion in the F9 promoter (NC_006621.3:g.109,501,492delC; CanFam3.1). Genotyping of the deletion in 1,298 dog specimens (81 different breeds) including 720 Hovawarts revealed that the mutant allele was only present in the aforementioned Hovawart family. The deletion is located 73 bp upstream of the F9 start codon in the highly conserved overlapping DNA binding sites of hepatocyte nuclear factor 4 (HNF4) and androgen receptor (AR). The deletion only abolishes binding of HNF4 as demonstrated by electrophoretic mobility shift assay (EMSA) using purified recombinant human HNF4 and a transient overexpression lysate of human AR with double-stranded DNA probes encompassing the mutant promoter region. Luciferase reporter assays using wild type and mutated promoter fragment constructs transfected into Hep G2 cells showed a 65.3% reduction in expression from the mutant promoter. The data presented here provide evidence that the deletion identified in the Hovawart family caused a rare type of hemophilia B resembling human hemophilia B Leyden.\n\nAuthor summaryHemophilia B is the rarer form of classical hemophilias resulting from the absence or residual activity of blood clotting factor IX. Due to its X-linked recessive inheritance normally only males are affected. In a disease subtype, termed hemophilia B Leyden, factor IX activities increase during puberty resulting in spontaneous improvement of bleeding symptoms or even clinical recovery. This surprising development-related alteration is caused by nucleotide variants in important developmental and hormone-responsive regulatory regions of the factor IX gene promoter interfering with transcription factor binding. Although hemophilia B has been reported in several dog breeds, subtypes resembling human hemophilia B Leyden were unknown hitherto. In addition, the single nucleotide deletion reported here in Hovawarts in the overlapping binding sites of transcription factor HNF4 and androgen receptor only affecting HNF4 binding, was unexpected. Although it is advisable to genotype females in the future to prevent a further spread of this subtype of the disorder, our findings also open up the possibility not to euthanize affected males inevitably but to treat until puberty if necessary.

genetics↗

bioRxiv2018

Hashimotos Thyroiditis-associated Thyroid Swelling among Adolescents Presenting with Benign Goiter in Lahore, Pakistan

BackgroundThe aim of this study was to determine frequency of Hashimotos thyroiditis (HT), by determination of serum TPO-Ab titer in goitrous adolescents attending Centre for Nuclear Medicine (CENUM), Mayo Hospital, Lahore, Pakistan.\n\nMethodSerum TPO-Ab was determined in 277 local goitrous adolescents (female 194, male 83) with euthyroidism or subclinical hypothyroidism. Their mean ({+/-}SD) age was 15.8 + ***2.5 years with age range 10 to 19 year. Female and male adolescents were comparable in age, goiter size and serum thyroid hormone levels.\n\nResultsMean TSH and percentage of TSH levels > 3.0 mIU/L was significantly higher in male adolescents. High serum TPO-Ab titer (> 20.0 IU/ml) or HT was detected in 38 (13.7%) patients. The incidence of HT in female (16.5%) was higher than male adolescents (7.2%) but the difference was not statistically significant (p=0.120). Similarly goiter size (palpable or visible) or patient age (below or above 16 year) has no significant effect on HT frequency. However, compared to adolescents with TSH within normal laboratory range those with TSH level above the upper normal limit (4.0 mIU/L) had significantly more frequency of HT (10.4% versus 30.4%; p=0.001).\n\nConclusionThus this study reports 13.7% prevalence of HT-associated goiter among local adolescents presenting with benign goiter, in Lahore Pakistan.

epidemiology↗

bioRxiv2018

AhRLK1, a CLAVATA1-like leucine-rich repeat receptor-like kinase of peanut, confers increased resistance to bacterial wilt in tobacco

Bacterial wilt caused by Ralstonia solanacearum is a devastating disease that infects hundreds of plant species. Host factors involved in disease resistance and pathogenesis remain poorly characterized. An up regulated and leucine-rich repeat receptor-like kinase characterized as CLAVATA1 and named AhRLK1 was obtained by microarray analysis in response to R. solanacearum in peanut. AhRLK1 contained presumably, a signal peptide, ten leucine-rich repeat (LRR) domains and conserved motifs of intracellular kinases. For subcellular localization, the AhRLK1 protein was visualized only in the plasma membrane. After inoculation with R. solanacearum, AhRLK1 was constantly up regulated in the susceptible variety Xinhuixiaoli but showed little changed in the resistant cultivar Yueyou92. Different hormones, including salicylic acid, abscisic acid, methyl jasmonate, and ethephon, induced expression, but expression was completely down regulated under cold and drought treatments. Transient overexpression provoked a hypersensitive response (HR) in Nicotiana benthamiana following agro-infiltration. Furthermore, in transgenic tobacco with overexpression of the gene, the resistance to R. solanacearum increased significantly. By contrast, most representative defense-responsive genes in HR, SA, JA and ET signal pathways such as NtHIN1, NtPR2, NtLOX1, and NtACS6, among others, were considerably up regulated in the AhRLK1 transgenic lines. Additionally, the EDS1 and PAD4 in the R gene signal were also up regulated in transgenic plants, but the NDR1 and NPR1 genes were down regulated. Accordingly, we suggest that AhRLK1 increases the defense response to R. solanacearum via HR and hormone defense signalling, associated with the EDS1 pathway of R gene signalling. The results provide new understanding of CLV1 function and will contribute to genetic enhancement of peanut.

plant biology↗

bioRxiv2018

Loss of CREST leads to neuroinflammatory responses and ALS-like motor defects in mice

Amyotrophic lateral sclerosis (ALS) is a late onset neurodegenerative disease with fast progression. Mutations of the CREST gene (also known as SS18L1) are identified in sporadic ALS patients. Whether CREST mutations may lead to ALS remained largely unclear. In this study, we showed that the ALS-related CREST-Q388X mutation exhibited loss-of-function effects. Importantly, we found that microglial activation were prevalent in CREST haploinsufficieny mice and the Q394X mice mimicking the human CREST Q388X mutation. Furthermore, we showed that both CREST haploinsufficieny and the Q394X mice displayed deficits in motor coordination. Finally, we identified the critical role of CREST-BRG1 complex in repressing the expression of immune-related cytokines including Ccl2 and Cxcl10 in neurons, via histone deacetylation, providing the molecular mechanisms underlying inflammatory responses lack of CREST. These findings indicate that elevated inflammatory responses in a subset of ALS may be caused by neuron-derived factors, suggesting potential therapeutic methods through inflammation pathways.\n\nIn BriefCheng et al. discovered that neuronal loss of CREST reduces the protein level of FUS, de-represses the transcriptional inhibition of chemokine genes which in turn causes microglial activation and proinflammation, and ultimately leads to axonal degeneration of motor neurons and impairment of locomotion.

neuroscience↗

bioRxiv2018

The critical role of ASD-related gene CNTNAP3 in regulating synaptic development and social behavior in mice

Accumulated genetic evidences indicate that the contactin associated protein-like (CNTNAP) family is implicated in autism spectrum disorders (ASD). In this study, we identified genetic mutations in the CNTNAP3 gene from Chinese Han ASD cohorts and Simons Simplex Collections. We found that CNTNAP3 interacted with synaptic adhesion proteins Neuroligin1 and Neuroligin2, as well as scaffolding proteins PSD95 and Gephyrin. Significantly, we found that CNTNAP3 played an opposite role in controlling the development of excitatory and inhibitory synapses in vitro and in vivo, in which ASD mutants exhibited loss-of-function effects. In this study, we showed that Cntnap3-null mice exhibited deficits in social interaction, spatial learning and prominent repetitive behaviors. These evidences elucidate the pivotal role of CNTNAP3 in synapse development and social behaviors, providing the mechanistic insights for ASD.

neuroscience↗