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Search indexed bioRxiv preprints in genomics, neuroscience, cell biology and bioinformatics. Read source abstracts and check manuscript versions; preprints are not peer reviewed.

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bioRxiv2018

Extreme Amyloid Polymorphism in Staphylococcus aureus Virulent PSMα Peptides

Members of the Staphylococcus aureus phenol-soluble modulin (PSM) peptide family are secreted as functional amyloids that serve diverse roles in pathogenicity and may be present as full-length peptides or as naturally occurring truncations. We recently showed that the activity of PSM3, the most toxic member, stems from the formation of cross- fibrils, which are at variance with the cross-{beta} fibrils linked with eukaryotic amyloid pathologies. Here, we show that PSM1 and PSM4, involved in biofilm structuring, form canonical cross-{beta} amyloid fibrils wherein {beta}-sheets tightly mate through steric zipper interfaces, conferring high stability. Contrastingly, a truncated PSM3 has antibacterial activity, forms reversible fibrils, and reveals two polymorphic and atypical {beta}-rich fibril architectures. These architectures are radically different from both the cross- fibrils formed by full-length PSM3, and from the canonical cross-{beta} fibrils. Our results point to structural plasticity being at the basis of the functional diversity exhibited by S. aureus PSMs.

biochemistry↗

bioRxiv2018

Adult-born neurons maintain hippocampal cholinergic inputs and support working memory during aging

Adult neurogenesis is impaired in disorders of stress, memory, and cognition though its normal function remains unclear. Moreover, a systems level understanding of how a small number of young hippocampal neurons could dramatically influence brain function is lacking. We examined whether adult neurogenesis sustains hippocampal connections across the life span. Long-term suppression of neurogenesis as occurs during stress and aging resulted in a progressing decline in hippocampal acetylcholine and the slow emergence of profound working memory deficits. These deficits were accompanied by compensatory rewiring of cholinergic dentate gyrus inputs such that ventrally projecting neurons were recruited by the dorsal projection. Our study demonstrates that hippocampal neurogenesis supports memory by maintaining the septohippocampal circuit across the lifespan. It also provides a systems level explanation for the progressive nature of memory deterioration during normal and pathological aging and indicates that the brain connectome is malleable by experience.

neuroscience↗

bioRxiv2018

INDEX-db: The Indian Exome Reference database (Phase-I)

Deep sequencing based genetic mapping has greatly enhanced the ability to catalog variants with plausible disease association. The bigger challenge now is to ascertain pathological significance to the array of identified variants to specific disease conditions. Differential selection pressure may impact frequency of genetic variations, and thus the detection of association with disease conditions, across populations. To understand the genotype to phenotype correlations, it thus becomes important to first understand the genetic variation spectrum of a population by creating a reference map. In this study, we report the development of phase I of a new database of coding variations, from the Indian population, with an aim to establish a centralized database of integrated information. This could be useful for researchers involved in studying disease mechanism at the clinical, genetic and cellular level.\n\nDatabase URL: http://indexdb.ncbs.res.in

genomics↗

bioRxiv2018

Single cell RNA-seq reveals profound transcriptional similarity between Barretts esophagus and esophageal glands

Barretts esophagus is a precursor of esophageal adenocarcinoma. In this common condition, squamous epithelium in the esophagus is replaced by columnar epithelium in response to acid reflux. Barretts esophagus is highly heterogeneous and its relationships to normal tissues are unclear. We investigated the cellular complexity of Barretts esophagus and the upper gastrointestinal tract using RNA-sequencing of 2895 single cells from multiple biopsies from four patients with Barretts esophagus and two patients without esophageal pathology. We found that uncharacterised cell populations in Barretts esophagus, marked by LEFTY1 and OLFM4, exhibit a profound transcriptional overlap with a subset of esophageal cells, but not with gastric or duodenal cells. Additionally, SPINK4 and ITLN1 mark cells that precede morphologically identifiable goblet cells in colon and Barretts esophagus, potentially aiding the identification of metaplasia. Our findings reveal striking transcriptional relationships between normal tissue populations and cells in a premalignant condition, with implications for clinical practice.

genetics↗

bioRxiv2018

Misoprostol regulates Bnip3 repression and alternative splicing to control cellular calcium homeostasis during hypoxic stress.

The cellular response to hypoxia involves the activation of a conserved pathway for gene expression regulated by the transcription factor complex called hypoxia-inducible factor (HIF). This pathway has been implicated in both the adaptive response to hypoxia and in several hypoxic-ischemic related pathologies. Perinatal hypoxic injury, often associated with prematurity, leads to multi-organ dysfunction resulting in significant morbidity and mortality. Using a rodent model of neonatal hypoxia and several representative cell lines, we observed HIF1 activation and down-stream induction of the cell death gene Bnip3 in brain, large intestine, and heart which was mitigated by administration of the prostaglandin E1 analog misoprostol. Mechanistically, we determined that misoprostol inhibits full-length Bnip3 (Bnip3-FL) expression through PKA-mediated NF-{kappa}B (P65) nuclear retention, and the induction of pro-survival splice variants. We observed that the dominant small pro-survival variant of Bnip3 in mouse cells lacks the third exon (Bnip3{Delta}Exon3), whereas human cells produce a pro-survival BNIP3 variant lacking exon 2 (BNIP3{Delta}Exon2). In addition, these small Bnip3 splice variants prevent mitochondrial dysfunction, permeability transition, and necrosis triggered by Bnip3-FL by blocking calcium transfer from the sarco/endoplasmic reticulum to the mitochondria. Furthermore, misoprostol and Bnip3{Delta}Exon3 promote nuclear calcium accumulation, resulting in HDAC5 nuclear export, NFAT activation, and adaptive changes in cell morphology and gene expression. Collectively, our data suggests that misoprostol can mitigate the potential damaging effects of hypoxia on multiple cell types by activating adaptive cell survival pathways through Bnip3 repression and alternative splicing.

cell biology↗

bioRxiv2018

3D Shape Modeling for Cell Nuclear Morphological Analysis and Classification

Quantitative analysis of morphological changes in a cell nucleus is important for the understanding of nuclear architecture and its relationship with pathological conditions such as cancer. However, dimensionality of imaging data, together with a great variability of nuclear shapes, presents challenges for 3D morphological analysis. Thus, there is a compelling need for robust 3D nuclear morphometric techniques to carry out population-wide analysis. We propose a new approach that combines modeling, analysis, and interpretation of morphometric characteristics of cell nuclei and nucleoli in 3D. We used robust surface reconstruction that allows accurate approximation of 3D object boundary. Then, we computed geometric morphological measures characterizing the form of cell nuclei and nucleoli. Using these features, we compared over 450 nuclei with about 1,000 nucleoli of epithelial and mesenchymal prostate cancer cells, as well as 1,000 nuclei with over 2,000 nucleoli from serum-starved and proliferating fibroblast cells. Classification of sets of 9 and 15 cells achieved accuracy of 95.4% and 98%, respectively, for prostate cancer cells, and 95% and 98% for fibroblast cells. To our knowledge, this is the first attempt to combine these methods for 3D nuclear shape modeling and morphometry into a highly parallel pipeline workflow for morphometric analysis of thousands of nuclei and nucleoli in 3D.

bioinformatics↗

bioRxiv2018

Expert Specification of the ACMG/AMP Variant Interpretation Guidelines for Genetic Hearing Loss

Due to the high genetic heterogeneity of hearing loss, current clinical testing includes sequencing large numbers of genes, which often yields a significant number of novel variants. Therefore, the standardization of variant interpretation is crucial to provide consistent and accurate diagnoses. The Hearing Loss Variant Curation Expert Panel was created within the Clinical Genome Resource to provide expert guidance for standardized genomic interpretation in the context of hearing loss. As one of its major tasks, our Expert Panel has adapted the American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) standards and guidelines for the interpretation of sequence variants in hearing loss genes. Here, we provide a comprehensive illustration of the newly specified ACMG/AMP hearing loss rules. Three rules remained unchanged, four rules were removed, and the remaining twenty-one rules were specified. Of the specified rules, four had general recommendations, seven were gene/disease considerations, seven had strength-level specifications, and three rules had both gene/disease and strength-level specifications. These rules were further validated and refined using a pilot set of 51 variants assessed by curators. These hearing loss-specific ACMG/AMP rules will help standardize variant interpretation, ultimately leading to better care for individuals with hearing loss.\n\nGRANT NUMBERSResearch reported in this publication was supported by the National Human Genome Research Institute (NHGRI) under award number U41HG006834.

genetics↗

bioRxiv2018

Molecular Subtypes of Anaplastic Gliomas Identified with Somatic-Mutation and Pathway Based Gene Signature

PurposeAnaplastic gliomas constitute heterogeneous population with variable outcomes and no consensus on therapeutic approach. Molecular profiling may provide prognostication beyond clinical and pathologic factors and help guide treatment decisions.\n\nExperimental DesignThe Cancer Genome Atlas (TCGA) was utilized to derive a 39-gene low grade glioma-specific gene signature. Consensus clustering based on expression of the signature identified subgroups for 176 patients with anaplastic glioma from TCGA. Overall survival (OS) was analyzed for each subgroup. A total of 68 patients from Repository for Molecular Brain Neoplasia Data (REMBRANDT) were used as an independent validation dataset.\n\nResultsConsensus clustering separated the TCGA group into two distinct cohorts. The OS was significantly different between two subgroups, 20 vs. 67 months (p<0.001). On univariate analysis, the molecular subgroup, age, KPS, IDH1/2 mutation, 1p19q-co-deletion, chemotherapy, and use of both chemotherapy and radiation-therapy were significantly associated with OS. On multivariable analysis, the molecular subgroup remained significant with HR of 2.6 (p=.047, 95%CI [1.01-6.68]). In an independent validation with REMBRANDT, consensus clustering based on the signature successfully identified similarly poor prognostic subgroup with median survival of 14 months and concordance of expression patterns in 21 of the genes.\n\nConclusionExpression patterns of the 39 gene stratified anaplastic gliomas into two distinct subgroups with substantially different OS. This molecular prognostication was validated in an external dataset. Utilization of molecular subgroup, in addition to known prognostic factors may help define those requiring aggressive therapeutic intervention. Characteristic genes within the poor prognostic group may represent potential targets for therapeutic intensification.\n\nSource code and dataset used in this work is available for reviewers at: https://www.taehyunlab.org/ntripath\n\nImportance of the studyDespite the revolution of tailored therapy, anaplastic gliomas represent a category of tumors without clear treatment recommendations. While current prognostic factors help guide therapy recommendations, further refinement with the addition of molecular markers can help physicians with treatment recommendations. In this study, we developed a 39 gene prognostic gene signature by utilizing Pan-Cancer TCGA mutation profiles of over 5,000 patients across 19 different TCGA cancer types to stratify patients with anaplastic gliomas. We performed consensus clustering based on gene expression profiles of our 39-gene signature without any consideration of clinical factors or outcomes to TCGA anaplastic gliomas patients as well as an independent dataset and successfully identified two molecular subgroups with distinct clinical outcome. We found that subgroups have remarkably different survivals with a clear poor prognostic group. Furthermore, the poor prognostic group showed significant benefits for aggressive multimodality therapy, justifying the use of intensive therapy based on molecular stratification.

genomics↗

bioRxiv2018

A direct comparison of four high risk human papilloma virus tests versus the cobas test for detecting cervical intraepithelial neoplasia and cervical cancer

This study is to evaluate performances and genotyping capabilities of four human papilloma virus (HR-HPV) tests based on real-time polymerase chain reaction (PCR) technology platforms compared with the cobas test. Discordant results were further analyzed using INNO-LiPA HPV genotyping test, the gold standard laboratory test to determine presence and type of HPV infection. Over 200 samples from Hospital patients were collected and analyzed using five HR-HPV tests. Women with positive test results were referred directly to colposcopy. If a positive result was returned, biopsies were administered for pathological classification. Clinical performances and genotyping capabilities between the four HR-HPV and cobas tests were compared and contrasted. High levels of agreement were observed, though all HR-HPV tests presented discrepancies compared with the cobas test. Cervical intraepithelial neoplasia Grade 2 or higher lesions (CIN2+) was set as the threshold, and all five tests performed with equally high sensitivity. Lower levels of specificity were observed across all five tests. Results suggest the four HR-HPV tests analyzed are as effective as the cobas test in genotyping capacities and diagnosing CIN. Therefore, these test kits should be used for HPV screening, especially in developing nations because they are cost effective and reliable. Minor discrepancies between tests are generally unavoidable though this may add complexity to the clinical decision-making process. As such, we recommend that efforts be made to standardize HPV genotyping tests as well as to optimize clinical sensitivity and specificity. Focusing on these issues will drive the development of HPV detection techniques, therefore save lives.

epidemiology↗

bioRxiv2018

Combining landscape genomics and ecological modelling to investigate local adaptation of indigenous Ugandan cattle to East Coast fever

East Coast fever (ECF) is a fatal sickness affecting cattle populations of eastern, central, and southern Africa. The disease is transmitted by the tick Rhipicephalus appendiculatus, and caused by the protozoan Theileria parva parva, which invades host lymphocytes and promotes their clonal expansion. Importantly, indigenous cattle show tolerance to infection in ECF-endemically stable areas. Here, the putative genetic bases underlying ECF-tolerance were investigated using molecular data and epidemiological information from 823 indigenous cattle from Uganda. Vector distribution and host infection risk were estimated over the study area and subsequently tested as triggers of local adaptation by means of landscape genomics analysis. We identified 41 and seven candidate adaptive loci for tick resistance and infection tolerance, respectively. Among the genes associated with the candidate adaptive loci are PRKG1 and SLA2. PRKG1 was already described as associated with tick resistance in indigenous South African cattle, due to its role into inflammatory response. SLA2 is part of the regulatory pathways involved into lymphocytes proliferation. Additionally, local ancestry analysis suggested the zebuine origin of the genomic region candidate for tick resistance.\n\nAuthor summaryThe tick-borne parasite Theileria parva parva infects cattle populations of eastern, central and southern Africa, by causing a highly fatal pathology called \"East Coast fever\". The disease is especially severe for the exotic breeds imported to Africa, as well as outside the endemic areas of East Africa. In these regions, indigenous cattle populations can survive to infection, and this tolerance might result from unique adaptations evolved to fight the disease. We investigated this hypothesis by using a method named \"landscape genomics\", with which we compared the genetic characteristics of indigenous Ugandan cattle coming from areas at different infection risk, and located genomic sites potentially attributable to tolerance. In particular, the method pinpointed two genes, one (PRKG1) involved into inflammatory response and potentially affecting East Coast fever vector attachment, the other (SLA2) involved into lymphocytes proliferation, a process activated by T. parva parva infection. Our findings can orientate future research on the genetic basis of East Coast fever-tolerance, and derive from a general method that can be applied to investigate adaptation in analogous host-vector-parasite systems. Characterization of the genetic factors underlying East Coast-fever-tolerance represents an essential step towards enhancing sustainability and productivity of local agroecosystems.

evolutionary biology↗

bioRxiv2018

Amazon Mechanical Turk as a platform for borderline personality disorder research

Researchers investigating the psychological processes underlying specific mental health problems often have difficulties achieving large enough samples for adequately powered studies. This can be particularly problematic when studying psychopathology with low base rates in typical samples (i.e., undergraduate and community). A relatively new approach to recruitment and testing employs online crowdsourcing to rapidly measure the characteristics and behavior of large numbers of people. We tested the feasibility of researching borderline personality disorder (BPD) in this manner using one large crowdsourcing site, Amazon Mechanical Turk (MTurk). Specifically, we examined prevalence rates of psychopathology in a large MTurk sample, as well as the demographic, psychosocial, and psychiatric characteristics of individuals who met criteria for BPD. These characteristics were compared across three groups: those who met criteria for BPD currently, those who met criteria for remitted BPD, and those who had never met criteria for BPD. The results suggest that MTurk may be ideally suited for studying individuals with a wide range of pathology, from healthy to intensely symptomatic to remitted.

animal behavior and cognition↗

bioRxiv2018

ANTI-MICROBIAL RESISTANCE IN AGENTS CAUSING URINARY TRACT INFECTIONS

BACKGROUNDUrinary Tract Infections are usually treated with empirical therapy by physicians based on previous knowledge of predictability of causative agents and their antimicrobial susceptibilities.\n\nOBJECTIVEThe objective of this study was to determine the frequency of various pathogens causing urinary tract infections and their antimicrobial susceptibility in patients presenting in out-patient department of a tertiary care hospital.\n\nMATERIALS AND METHODSThis descriptive cross sectional study was conducted in Out-Patient department of Urology of Benazir Bhutto Hospital during a period of 6 months from January 2017 to June 2017 after ethical approval from institutional research forum of Rawalpindi Medical University. 1000 patients (12 years old or above) that were clinically suspected for urinary tract infections were included in this study. Patients with co-morbidities like diabetes mellitus, renal pathologies, Immunodeficiency disorders, malignancies and congenital urogenital disorders were also excluded. Recipients of corticosteroid therapy or with a history of intake of broad spectrum antibiotics in previous 15 days were also excluded. Modified Kirby-Bauer disc diffusion method was used for determining the antimicrobial resistance against various antimicrobials.\n\nRESULTSA total of 530 (53%) isolates were found to be culture positive for E.coli(77.4%),Klebsiella (6.4%), Enterobacter (6.0%), Pseudomonas (3.8%), Staphylococcus saprophyticus (3.4%), Citrobacter (1.1%) and Morganella (0.4%).\n\nAntimicrobial resistance against commonly used antimicrobials was alarmingly high\n\nCONCLUSIONSurveillance of trends of antimicrobial susceptibility pattern is highly important.

microbiology↗

bioRxiv2018

Type IV collagen is essential for proper function of integrin-mediated adhesion in Drosophila muscle fibers

Congenital muscular dystrophy (CMD), a subgroup of myopathies and a genetically and clinically heterogeneous group of inherited muscle disorders is characterized by progressive muscle weakness, fiber size variability, fibrosis, clustered necrotic fibers, and central myonuclei present in regenerating muscle. Type IV collagen (COL4A1) mutations have recently been identified in patients with intracerebral, vascular, renal, ophthalmologic pathologies and congenital muscular dystrophy, consistent with diagnoses of Walker-Warburg Syndrome or Muscle-Eye-Brain disease. Morphological characteristics of muscular dystrophy have also been demonstrated Col4a1 mutant mice. Yet, several aspects of the pathomechanism of COL4A1-associated muscle defects remained largely uncharacterized. Based on the results of genetic, histological, molecular, and biochemical analyses in an allelic series of Drosophila col4a1 mutants, we provide evidence that col4a1 mutations associate with severely compromised muscle fibers within the single-layer striated muscle of the common oviduct, characterized by loss of sarcomere structure, disintegration and streaming of Z-discs, and aberrant integrin expression within the M-discs, indicating an essential role for the COL4A1 protein. Features of altered cytoskeletal phenotype include actin bundles traversing over sarcomere units, amorphous actin aggregates, atrophy and aberrant fiber size. The mutant COL4A1-associated defects appear to recapitulate integrin-mediated adhesion phenotypes observed in Drosophila by RNA-inhibition. Our results provide insight into the mechanistic details of COL4A1-associated muscle disorders and suggest a role for integrin-collagen interaction in the maintenance of sarcomeres.

genetics↗

bioRxiv2018

Kinase activity simultaneously determines the constitutive and the orthosteric gating in α4β1/3δ GABAA receptors in hippocampal granule cells

A subset of the GABAA receptors expressed in recombinant systems and neurons is known to exhibit both constitutive- and agonist-induced gating. Two such receptors are the {delta}-subunit containing GABAA receptors 4{beta}1{delta} and 4{beta}3{delta}, which are expressed in adult rodent hippocampal dentate gyrus granule cells (DGGCs). Here we show that the GABAA receptor mediated tonic current recorded in the presence of tetrodotoxin in adult rodent DGGCs is almost exclusively mediated by constitutively active {delta}-subunit containing GABAA receptors and that the constitutive current is absent in recordings at 24 {degrees}C or in recordings at 34 {degrees}C including an intracellular inhibitor of protein kinase C. These factors simultaneously govern the efficacy of an orthosteric agonist at 4{beta}1/3{delta} receptors, Thio-THIP, in a reciprocal manner. In the absence of constitutive receptor activity, the efficacy of Thio-THIP was increased approximately four-fold relative to recording conditions that favors constitutive activity. Further, only under conditions of an absent constitutive current, the classified neutral antagonist gabazine (GBZ) alone, induced a tonic current in DGGCs (EC50 2.1 M). This effect of GBZ was not seen in recording conditions of high constitutive activity, was inhibited by picrotoxin (PTX), potentiated by DS2, completely absent in {delta}-/- mice and reduced in {beta}1-/- mice, but could not be replicated in human 4{beta}1/3{delta} receptors expressed recombinantly in HEK cells. We hypothesize that specific intracellular components in neurons interact with receptors to determine constitutive gating and receptor responsiveness to orthosteric ligands.\n\nSignificance statementThe presented data highlight how recording conditions for whole cell patch clamp analysis of 4{beta}1/3{delta} GABAA receptors can mask important pharmacological effects. Specifically, orthosteric agonists appear with reduced efficacy, and other ligands, here exemplified with the well-known antagonist GBZ, are misinterpreted as being inactive/neutral, although they could have effect in constitutively silent receptors. Unmasking of potential hidden effects are easily done using recording conditions of reduced kinase activity in a relevant neuronal context. It follows that in pathologies with changes in phosphorylation level of {delta}-subunit containing GABAA receptors, the efficacy of an agonist of these receptors, measured by whole-cell recordings in vitro, will not match the efficacy of the same agonist in an unperturbed neuron in vivo.

neuroscience↗

bioRxiv2018

Integrated Clinical and Omics Approach to Rare Diseases: Novel Genes and Oligogenic Inheritance in Holoprosencephaly

PurposeHoloprosencephaly (HPE) is a pathology of forebrain development characterized by high phenotypic and locus heterogeneity. Seventeen genes are known so far in HPE but the understanding of its genetic architecture remains to be refined. Here, we investigated the oligogenic nature of HPE resulting from accumulation of variants in different relevant genes.\n\nMethodsExome data from 29 patients diagnosed with HPE and 51 relatives from 26 unrelated families were analyzed. Standard variant classification approach was improved with a gene prioritization strategy based on clinical ontologies and gene co-expression networks. Clinical phenotyping and exploration of cross-species similarities were further performed on a family-by-family basis.\n\nResultsWe identified 232 rare deleterious variants in HPE patients representing 180 genes significantly associated with key pathways of forebrain development including Sonic Hedgehog (SHH) and Primary Cilia. Oligogenic events were observed in 10 families and involved novel HPE genes including recurrently mutated genes (FAT1, NDST1, COL2A1 and SCUBE2) and genes implicated in cilia function.\n\nConclusionsThis study reports novel HPE-relevant genes and reveals the existence of oligogenic cases resulting from several mutations in SHH-related genes. It also underlines that integrating clinical phenotyping in genetic studies will improve the identification of causal variants in rare disorders.

genetics↗

bioRxiv2018

Arterial smooth muscle cell PKD2 (TRPP1) channels control systemic blood pressure

Systemic blood pressure is determined, in part, by arterial smooth muscle cells (myocytes). Several Transient Receptor Potential (TRP) channels are proposed to be expressed in arterial myocytes, but it is unclear if these proteins control physiological blood pressure and contribute to hypertension in vivo. We generated the first inducible, smooth muscle-specific knockout for a TRP channel, namely for PKD2 (TRPP1), to investigate arterial myocyte and blood pressure regulation by this protein. Using this model, we show that intravascular pressure and 1-receptors activate PKD2 channels in arterial myocytes of different systemic organs. PKD2 channel activation in arterial myocytes leads to an inward Na+ current, membrane depolarization and vasoconstriction. Inducible, smooth muscle cell-specific PKD2 knockout lowers both physiological blood pressure and hypertension and prevents pathological arterial remodeling during hypertension. In summary, we show for the first time that arterial myocyte PKD2 channels control systemic blood pressure and targeting reduces high blood pressure.

neuroscience↗

bioRxiv2018

Endothelial and non-endothelial responses to estrogen excess during development lead to vascular malformations

Excess estrogen signaling is associated with vascular malformations and pathologic angiogenesis, as well as tumor progression and metastasis. Yet, how dysregulated estrogen signaling impacts vascular morphogenesis in vivo remains elusive. Here we use live imaging of zebrafish embryos to determine the effects of excess estrogen signaling on the developing vasculature. We find that excess estrogens during development induce intersegmental vessel defects, endothelial cell-cell disconnections, and a shortening of the circulatory loop due to arterial-venous segregation defects. Whole-mount in situ hybridization and qPCR analyses reveal that excess estrogens negatively regulate Sonic hedgehog (Hh)/Vegf/Notch signaling. Activation of Hh signaling with SAG partially rescues the estrogen-induced vascular defects. Similarly, increased vegfaa bioavailability, using flt1/vegfr1 mutants or embryos overexpressing vegfaa165, also partially rescues the estrogen-induced vascular defects. We further find that excess estrogens promote aberrant endothelial cell (EC) migration, possibly as a result of increased PI3K and Rho GTPase signaling. Using estrogen receptor mutants and pharmacological studies, we show that Esr1 and the G-protein coupled estrogen receptor (Gper1) are the main receptors driving the estrogen-induced vascular defects. Mosaic overexpression of gper1 in ECs promotes vascular disconnections and aberrant migration, whereas no overt vascular defects were observed in mosaic embryos overexpressing wild-type or constitutively active nuclear estrogen receptors in their ECs. In summary, developmental estrogen excess leads to a mispatterning of the forming vasculature. Gper1 can act cell-autonomously in ECs to cause disconnections and aberrant migration, whilst Esr signaling predominantly downregulates Hh/Vegf/Notch signaling leading to impaired angiogenesis and defective arterial-venous segregation.\n\nSubject codes: angiogenesis, animal models of human disease, mechanisms, vascular biology.

developmental biology↗

bioRxiv2018

Gold Nanoprisms as Optical Coherence Tomography Contrast Agents in the Second Near Infrared Window for Enhanced Angiography in Live Animals

Optical coherence tomography angiography (OCTA) is an important tool for investigating vascular networks and microcirculation in living tissue. Traditional OCTA detects blood vessels via intravascular dynamic scattering signals derived from the movements of red blood cells (RBCs). However, the low hematocrit and long latency between RBCs in capillaries makes these OCTA signals discontinuous, leading to incomplete mapping of the vascular networks. OCTA imaging of microvascular circulation is particularly challenging in tumors due to the abnormally slow blood flow in angiogenic tumor vessels and strong attenuation of light by tumor tissue. Here we demonstrate in vivo that gold nanoprisms (GNPRs) can be used as OCT contrast agents working in the second near infrared window, significantly enhancing the dynamic scattering signals in microvessels and improving the sensitivity of OCTA in skin tissue and melanoma tumors in live mice. This is the first demonstration that nanoparticle-based OCT contrast agent work in vivo in the second near infrared window, which allows deeper imaging depth by OCT. With GNPRs as contrast agents, the post-injection OCT angiograms showed 41% and 59% more microvasculature than pre-injection angiograms in healthy mouse skin and melanoma tumors, respectively. By enabling better characterization of microvascular circulation in vivo, GNPR-enhanced OCTA could lead to better understanding of vascular functions during pathological conditions, more accurate measurements of therapeutic response, and improved patient prognoses.

bioengineering↗