Biology subjects

Hao, W.

Publications and source records attributed to Hao, W..

27 records · Page 2Linked to original sources

bioRxiv2021

Deficiency of p38α-MAPK in myeloid cells ameliorates symptoms and pathology of APP-transgenic Alzheimer's disease mice

Microglial activation is a hall marker of Alzheimers disease (AD); its pathogenic role and regulating mechanisms are unclear. p38-MAPK, a stress-responding kinase, is activated in AD brain in early disease stages. In APP-transgenic mice, we deleted p38-MAPK in whole myeloid cells from birth or specifically in microglia from 9 months, and analysed AD pathology at the age of 4, 9 and 12 months. In both experimental settings, p38-MAPK deficiency decreased cerebral A{beta} and improved cognitive function of AD mice; however, p38-MAPK-deficient myeloid cells were more effective than p38-MAPK-deficient microglia in preventing AD pathogenesis. Deficiency of p38-MAPK in myeloid cells inhibited the inflammatory activation of individual microglia by 4 months, but enhanced it by 9 months. Inflammatory activation was essential for p38-MAPK deficiency to promote microglial internalization of A{beta}. Interestingly, p38-MAPK deficiency in peripheral myeloid cells reduced il-17a transcription in CD4-positive spleen cells. By cross-breeding APP-transgenic mice and IL-17a knockout mice, we further observed that IL-17a deficiency activated microglia and decreased A{beta} deposits in AD mouse brain. Thus, p38-MAPK deficiency in myeloid cells prevents AD pathogenesis, perhaps through reducing IL-17a-expressing T lymphocytes, and promoting A{beta} clearance in the brain. Our study supports p38-MAPK as a novel target for AD therapy.

neuroscience↗

bioRxiv2021

Nuclear soluble cGAS senses DNA virus infection

The cytosolic DNA sensor cGAS detects foreign DNA from pathogens or self-DNA from cellular damage and instigates type I interferon (IFN) expression. Recent studies find that cGAS also localizes in the nucleus and binds the chromatin. Despite how cGAS is inhibited in the nucleus is well elucidated, whether nuclear cGAS participates in DNA sensing is not clear. Here, we report that herpes simplex virus 1 (HSV-1) infection caused the release of cGAS from the chromatin into the nuclear soluble fraction. Like its cytosolic counterpart, the leaked nuclear soluble cGAS could sense viral DNA, produce cGAMP, and induce mRNA expression of type I IFN and interferon-stimulated genes. Furthermore, the nuclear cGAS limited HSV-1 infection. Taken together, our study demonstrates that HSV-1 infection releases cGAS from the chromatin tethering and, in turn, the nuclear soluble cGAS activates type I IFN production.

immunology↗

bioRxiv2020

Data driven mathematical model of colon cancer progression

Every colon cancer has its own unique characteristics, and therefore may respond differently to identical treatments. Here, we develop a data driven mathematical model for the interaction network of key components of immune microenvironment in colon cancer. We estimate the relative abundance of each immune cell from gene expression profiles of tumors, and group patients based on their immune patterns. Then we compare the tumor sensitivity and progression in each of these groups of patients, and observe differences in the patterns of tumor growth between the groups. For instance, in tumors with a smaller density of naive macrophages than activated macrophages, a higher activation rate of macrophages leads to an increase in cancer cell density, demonstrating a negative effect of macrophages. Other tumors however, exhibit an opposite trend, showing a positive effect of macrophages in controlling tumor size. Although the results indicate that for all patients, the size of the tumor is sensitive to the parameters related to macrophages such as their activation and death rate, this research demonstrates that no single biomarker could predict the dynamics of tumors.

cancer biology↗

bioRxiv2020

Mechanism of duplex unwinding by coronavirus nsp13 helicases

The current COVID-19 pandemic urges in-depth investigation into proteins encoded with coronavirus (CoV), especially conserved CoV replicases. The nsp13 of highly pathogenic MERS-CoV, SARS-CoV-2, and SARS-CoV exhibit the most conserved CoV replicases. Using single-molecule FRET, we observed that MERS-CoV nsp13 unwound DNA in discrete steps of approximately 9 bp when ATP was used. If another NTP was used, then the steps were only 4 to 5 bp. In dwell time analysis, we detected 3 or 4 hidden steps in each unwinding process, which indicated the hydrolysis of 3 or 4 dTTP. Based on crystallographic and biochemical studies of CoV nsp13 helicases, we modeled an unwinding mechanism similar to the spring-loaded mechanism of HCV NS3 helicase, although our model proposes that flexible 1B and stalk domains, by allowing a lag greater than 4 bp during unwinding, cause the accumulated tension on the nsp13-DNA complex. The hinge region between two RecA-like domains in SARS-CoV-2 nsp13 is intrinsically more flexible than in MERS-CoV nsp13 due to the difference of a single amino acid, which causes the former to induce significantly greater NTP hydrolysis. Our findings thus establish a blueprint for determining the unwinding mechanism of a unique helicase family. O_LIWhen dTTP was used as the energy source, 4 hidden steps in each individual unwinding step after 3 - 4 NTP hydrolysis were observed. C_LIO_LIAn unwinding model of MERS-CoV-nsp13 which is similar to the spring-loaded mechanism of HCV NS3 helicase, except the accumulation of tension on nsp13/DNA complex is caused by the flexible 1B and stalk domains that allow a lag of 4-bp in unwinding. C_LIO_LIComparing to MERS-CoV nsp13, the hinge region between two RecA-like domains in SARS-CoV-2 nsp13 is intrinsically more flexible due to a single amino acid difference, which contributes to the significantly higher NTP hydrolysis by SARS-CoV-2 nsp13. C_LI

biophysics↗

bioRxiv2020

Binding of the SARS-CoV-2 Spike Protein to Glycans

The pandemic of SARS-CoV-2 has caused a high number of deaths in the world. To combat it, it is necessary to develop a better understanding of how the virus infects host cells. Infection normally starts with the attachment of the virus to cell-surface glycans like heparan sulfate (HS) and sialic acid-containing oligosaccharides. In this study, we examined and compared the binding of the subunits and spike (S) proteins of SARS-CoV-2 and SARS-CoV, MERS-CoV to these glycans. Our results revealed that the S proteins and subunits can bind to HS in a sulfation-dependent manner, the length of HS is not a critical factor for the binding, and no binding with sialic acid residues was detected. Overall, this work suggests that HS binding may be a general mechanism for the attachment of these coronaviruses to host cells, and supports the potential importance of HS in infection and in the development of antiviral agents against these viruses.Competing Interest StatementThe authors have declared no competing interest.View Full Text

biochemistry↗

bioRxiv2020

Identifying Priority Landscapes for Conservation of Snow Leopards in Pakistan

Pakistans total estimated snow leopard habitat is about 80,000 km2 of which about half is considered prime. However, this preliminary demarcation was not always in close agreement with the actual distribution--the discrepancy may be huge at the local and regional level. Recent technological developments like camera trapping and molecular genetics allow for collecting reliable presence records that could be used to construct realistic species distribution based on empirical data and advanced mathematical approaches like MaxEnt. Current study followed this approach to construct accurate distribution of the species in Pakistan. Moreover, movement corridors, among different landscapes, were also identified through the circuit theory. The habitat suitability map, generated from 384 presence points and 28 environmental variables, scored the snow leopards assumed range in Pakistan, from 0 to 0.97. A large shear of previously known range represented low-quality habitat, including areas in lower Chitral, Swat, Astore and Kashmir. Conversely, Khunjerab, Misgar, Chapursan, Qurumber, Broghil, and Central Karakoram represented high-quality habitats. Variables with higher contribution in the MaxEnt model were precipitation of driest month (34%), annual mean temperature (19.5%), mean diurnal range of temperature (9.8%), annual precipitation (9.4%) and river density (9.2). The validation texts suggest a good model fit, and strong prediction power. The connectivity analysis revealed that the population in the Hindukush landscape appears to be more connected with the population in Afghanistan as compared to other populations in Pakistan. Similarly, the Pamir-Karakoram population is better connected with China and Tajikistan, while the Himalayan population was with the population in India. Current study allows for proposing three model landscapes to be considered under GSLEP agenda as regional priority areas, to safeguard safeguard future of the species in the long run. These landsacpes fall in mountain ranges of the Himalaya, Hindu Kush and Karakoram-Pamir, respectively. We also identified gaps in existing protected areas network, and suggest new protected areas in Chitral and Gilgit-Baltistan to protect critical habitats of snow leopard in Pakistan.

zoology↗

bioRxiv2018

Fin whale (Balaenoptera physalus) mitogenomics: A cautionary tale of defining sub-species from mitochondrial sequence monophyly

HighlightsO_LIMitochondrial monophyly is commonly employed to define evolutionary significant units.\nC_LIO_LIMonophyly may be caused by insufficient sampling or a recent common ancestor.\nC_LIO_LIMitogenomic studies are generally based on few samples and prone to sampling issues.\nC_LIO_LIExpanded mitogenome sampling negates previous monophyly in fin whales.\nC_LI\n\nAbstractThe advent of massive parallel sequencing technologies has resulted in an increase of studies based upon complete mitochondrial genome DNA sequences that revisit the taxonomic status within and among species. Spatially distinct monophyly in mitogenomic genealogies, i.e., the sharing of a recent common ancestor among con-specific samples collected in the same region has been viewed as evidence for subspecies. Several recent studies in cetaceans have employed this criterion to suggest subsequent intraspecific taxonomic revisions. We reason that employing intra-specific, spatially distinct monophyly at non-recombining, clonally inherited genomes is an unsatisfactory criterion for defining subspecies based upon theoretical (genetic drift) and practical (sampling effort) arguments. This point is illustrated by a re-analysis of a global mitogenomic assessment of fin whales, Balaenoptera physalus spp., published by Archer et al. (2013) which proposed to further subdivide the Northern Hemisphere fin whale subspecies, B. p. physalus. The proposed revision was based upon the detection of spatially distinct monophyly among North Atlantic and North Pacific fin whales in a genealogy based upon complete mitochondrial genome DNA sequences. The extended analysis conducted in this study (1,676 mitochondrial control region, 162 complete mitochondrial genome DNA sequences and 20 microsatellite loci genotyped in 358 samples) revealed that the apparent monophyly among North Atlantic fin whales reported by Archer et al. (2013) to be due to low sample sizes. In conclusion, defining sub-species from monophyly (i.e., the absence of para-or polyphyly) can lead to erroneous conclusions due to relatively \"trivial\" aspects, such as sampling. Basic population genetic processes (i.e., genetic drift and migration) also affect the time to most recent common ancestor and hence the probability that individuals in a sample are monophyletic.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=195 SRC=\"FIGDIR/small/488130v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (28K):\norg.highwire.dtl.DTLVardef@1e38e54org.highwire.dtl.DTLVardef@9533eborg.highwire.dtl.DTLVardef@183b5b5org.highwire.dtl.DTLVardef@eae09_HPS_FORMAT_FIGEXP M_FIG C_FIG

evolutionary biology↗

bioRxiv2018

Computational Modeling of the Dynamic Biomarker Cascade in Alzheimer’s Disease

BackgroundAlzheimers disease (AD) is a major public health concern and there is an urgent need to better understand its complex biology and develop effective therapies. AD progression can be tracked in patients though validated imaging and spinal fluid biomarkers of pathology and neuronal loss. We still, however, lack a coherent quantitative model that explains how these biomarkers interact and evolve over time. Such a model could potentially help identify the major drivers of disease in individual patients and simulate response to therapy prior to entry in clinical trials. A current theory of AD biomarker progression, known as the dynamic biomarker cascade model, hypothesizes AD biomarkers evolve in a sequential, but temporally overlapping manner. A computational model incorporating assumptions about the underlying biology of this theory and its variations would be useful to test and refine its accuracy with longitudinal biomarker data from clinical trials.\n\nMethodsWe implemented a causal model to simulate time-dependent biomarker data under the descriptive assumptions of the dynamic biomarker cascade theory. We modeled pathologic biomarkers (beta-amyloid and tau), neuronal loss biomarkers and cognitive impairment as non-linear first order ordinary differential equations (ODEs) to include amyloid-dependent and non-dependent neurodegenerative cascades. We tested the feasibility of the model by adjusting its parameters to simulate three specific natural history scenarios in early-onset autosomal dominant AD and late-onset AD, and determine whether computed biomarker trajectories agreed with current assumptions of AD biomarker progression. We also simulated the effects of anti-amyloid therapy in late-onset AD.\n\nResultsThe computational model of early-onset AD demonstrated the initial appearance of amyloid, followed by biomarkers of tau and neurodegeneration, followed by onset of cognitive decline based on cognitive reserve, as predicted by prior literature. Similarly, the late-onset AD computational models demonstrated the first appearance of amyloid or non-amyloid-related tauopathy, depending on the magnitude of comorbid pathology, and also closely matched the biomarker cascades predicted by prior literature. Forward simulation of anti-amyloid therapy in symptomatic late-onset AD failed to demonstrate any slowing in progression of cognitive decline, consistent with prior failed clinical trials in symptomatic patients.\n\nConclusionWe have developed and computationally implemented a mathematical causal model of the dynamic biomarker cascade theory in AD. We demonstrate the feasibility of this model by simulating biomarker evolution and cognitive decline in early and late-onset natural history scenarios, as well as in a treatment scenario targeted at core AD pathology. Models resulting from this causal approach can be further developed and refined using patient data from longitudinal biomarker studies, and may in the future play a key role in personalizing approaches to treatment.

neuroscience↗

bioRxiv2017

Extending Tests of Hardy-Weinberg Equilibrium to Structured Populations

Testing for Hardy-Weinberg equilibrium (HWE) is an important component in almost all analyses of population genetic data. Genetic markers that violate HWE are often treated as special cases; for example, they may be flagged as possible genotyping errors or they may be investigated more closely for evolutionary signatures of interest. The presence of population structure is one reason why genetic markers may fail a test of HWE. This is problematic because almost all natural populations studied in the modern setting show some degree of structure. Therefore, it is important to be able to detect deviations from HWE for reasons other than structure. To this end, we extend statistical tests of HWE to allow for population structure, which we call a test of \"structural HWE\" (sHWE). Additionally, our new test allows one to automatically choose tuning parameters and identify accurate models of structure. We demonstrate our approach on several important studies, provide theoretical justification for the test, and present empirical evidence for its utility. We anticipate the proposed test will be useful in a broad range of analyses of genome-wide population genetic data.

genomics↗