Biology subjects

Sharma, D.

Publications and source records attributed to Sharma, D..

At least 55 records · Page 3Linked to original sources

bioRxiv2023

Natural killer cell regulation of breast cancer stem cells mediates metastatic dormancy.

Breast cancer patients with estrogen receptor positive tumors face a constant risk of disease recurrence for the remainder of their lives. Dormant tumor cells residing in tissues such as the bone marrow may generate clinically significant metastases many years after initial diagnosis. Previous studies suggest that dormant cells display "stem like" properties (CSCs), which may be regulated by the immune system. Although many studies have examined tumor cell intrinsic characteristics of dormancy, the role of the immune system in controlling dormancy and its escape is not well understood. This scientific gap is due, in part, to a lack of immunocompetent mouse models of breast cancer dormancy with many studies involving human xenografts in immunodeficient mice. To overcome this limitation, we studied dormancy in immunocompetent, syngeneic mouse breast cancer models. We find that PyMT, Met-1 and D2.0R cell lines contain CSCs that display both short- and long-term metastatic dormancy in vivo, which is dependent on the host immune system. Natural killer cells were key for the metastatic dormancy phenotype observed for D2.0R and the role of NK cells in regulating CSCs was further investigated. Quiescent D2.0R CSC are resistant to NK cytotoxicity, while proliferative D2.0R CSC were sensitive to NK cytotoxicity both in vitro and in vivo. This resistance was mediated, in part, by the expression of Bach1 and Sox2 transcription factors. NK killing was enhanced by the STING agonist MSA-2. Collectively, our findings demonstrate the important role of immune regulation of breast tumor dormancy and highlight the importance of utilizing immunocompetent models to study this phenomenon.

cancer biology↗

bioRxiv2023

Neuroinflammation induces nerve growth factor dependent nociceptor sensitisation in a neonatal rodent model of platinum-based chemotherapy induced neuropathic pain

Chemotherapy-induced neuropathic pain (CINP) is a common adverse health related comorbidity that manifests later in life in paediatric patients treated for cancer. CIPN pathology progressively develops over time resulting in a delayed but long-lasting neuropathic pain. Current analgesic strategies are ineffective, aligning closely with our lack of understanding of CINP. Recent studies have indicated alterations in sensory neuronal maturation as component of CINP. The aim of this study was to investigate how cisplatin induces nerve growth factor mediated neuroinflammation and nociceptor sensitisation. In a rodent model of cisplatin induced survivorship pain, there was a significant infiltration of nerve growth factor positive macrophages into the dorsal root ganglia (DRG), demonstrating a robust neuroinflammatory response. Additionally, it was observed that CD11b/F480 positive monocyte/macrophages challenged with cisplatin expressed more NGF. Additionally, DRG derived primary sensory neuron cultures from neonatal mice demonstrated enhanced NGF-dependent TRPV1 mediated nociceptor activity after cisplatin treatment. Increased nociceptor activity was also observed when cultured neurons were treated with conditioned media from cisplatin activated monocyte/macrophages. This elevated nociceptor activity was dose-dependently inhibited by a neutralising monoclonal antibody to NGF. Intraperitoneal administration of NGF neutralising antibody significant reduction in mechanical hypersensitivity was given to mice with cisplatin-induced juvenile survivorship pain there was a as well as suppression of cisplatin induced aberrant nociceptor intraepidermal nerve fibre density. These findings identify the NGF/TrkA signalling pathway as a potential novel therapeutic target for analgesia in adult survivors of childhood cancer.

neuroscience↗

bioRxiv2023

Dual α-globin and truncated erythropoietin receptor knock-in restores hemoglobin production in α-thalassemia major-derived hematopoietic stem and progenitor cells

Alpha-thalassemia is an autosomal recessive disease with increasing worldwide prevalence. The molecular basis is due to mutation or deletion of one or more duplicated -globin genes, and disease severity is directly related to the number of allelic copies compromised. The most severe form, -thalassemia major (TM), results from loss of all four copies of -globin and has historically resulted in fatality in utero. However, in utero transfusions now enable survival to birth. Postnatally, patients face challenges similar to {beta}-thalassemia, including severe anemia and erythrotoxicity due to imbalance of {beta}-globin and -globin chains. While curative, hematopoietic stem cell transplantation (HSCT) is limited by donor availability and potential transplant-related complications. Despite progress in genome editing treatments for {beta}-thalassemia, there is no analogous curative option for patients suffering from -thalassemia. To address this, we designed a novel Cas9/AAV6-mediated genome editing strategy that integrates a functional -globin gene into the {beta}-globin locus in TM patient-derived hematopoietic stem and progenitor cells (HSPCs). Incorporation of a truncated erythropoietin receptor transgene into the -globin integration cassette dramatically increased erythropoietic output from edited HSPCs and led to the most robust production of -globin, and consequently normal hemoglobin. By directing edited HSPCs toward increased production of clinically relevant RBCs instead of other divergent cell types, this approach has the potential to mitigate the limitations of traditional HSCT for the hemoglobinopathies, including low genome editing and low engraftment rates. These findings support development of a definitive ex vivo autologous genome editing strategy that may be curative for -thalassemia. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=177 SRC="FIGDIR/small/555926v2_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@1b63dacorg.highwire.dtl.DTLVardef@18b25a1org.highwire.dtl.DTLVardef@53835corg.highwire.dtl.DTLVardef@d52bf5_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2023

Olfactomedin-4+ neutrophils exacerbate intestinal epithelial damage and worsen host survival after Clostridioides difficile infection.

Neutrophils are key first responders to Clostridioides difficile infection (CDI). Excessive tissue and blood neutrophils are associated with worse histopathology and adverse outcomes, however their functional role during CDI remains poorly defined. Utilizing intestinal epithelial cell (IEC)-neutrophil co-cultures and a pre-clinical animal model of CDI, we show that neutrophils exacerbate C. difficile-induced IEC injury. We utilized cutting-edge single-cell transcriptomics to illuminate neutrophil subtypes and biological pathways that could exacerbate CDI-associated IEC damage. As such, we have established the first transcriptomics atlas of bone marrow (BM), blood, and colonic neutrophils after CDI. We found that CDI altered the developmental trajectory of BM and blood neutrophils towards populations that exhibit gene signatures associated with pro-inflammatory responses and neutrophil-mediated tissue damage. Similarly, the transcriptomic signature of colonic neutrophils was consistent with hyper-inflammatory and highly differentiated cells that had amplified expression of cytokine-mediated signaling and degranulation priming genes. One of the top 10 variable features in colonic neutrophils was the gene for neutrophil glycoprotein, Olfactomedin 4 (OLFM4). CDI enhanced OLFM4 mRNA and protein expression in neutrophils, and OLFM4+ cells aggregated to areas of severe IEC damage. Compared to uninfected controls, both humans and mice with CDI had higher concentrations of circulating OLFM4; and in mice, OLFM4 deficiency resulted in faster recovery and better survival after infection. Collectively, these studies provide novel insights into neutrophil-mediated pathology after CDI and highlight the pathogenic role of OLFM4+ neutrophils in regulating CDI-induced IEC damage. One Sentence SummaryUtilizing single-cell transcriptomics, IEC-epithelial co-cultures, and pre-clinical models of CDI, we have identified a subset of neutrophils that are marked by OLFM4 expression as pathogenic determinants of IEC barrier damage after CDI.

immunology↗

bioRxiv2023

A sucrose non-fermenting-1-related protein kinase 1 gene from wheat, TaSnRK1α regulates starch biosynthesis by modulating AGPase activity

Major portion of wheat grain consist of carbohydrate, mainly starch. The proportion of amylose and amylopectin in starch greatly influence the end product quality. Advancement in understanding starch biosynthesis pathway and modulating key genes has enabled the genetic modification of crops resulting in enhanced starch quality. However, the regulation of starch biosynthesis genes still remains unexplored. So, to expand the limited knowledge, here, we characterized a Ser/Thr kinase, SnRK1 in wheat and determined its role in regulating starch biosynthesis. SnRK1 is an evolutionary conserved protein kinase and share homology to yeast SNF1. Yeast complementation assay suggest TaSnRK1 restore growth defect and promotes glycogen accumulation. Domain analysis and complementation assay with truncated proteins suggest the importance of ATP-binding and UBA domain in TaSnRK1 activity. Sub-cellular localization identified nuclear and cytoplasmic localization of TaSnRK1 in tobacco leaves. Further, heterologous over-expression (O/E) of TaSnRK1 in Arabidopsis not only led to increase in starch content but also enlarges the starch granules. TaSnRK1 was found to restore starch accumulation in Arabidopsis kin10. Remarkably, TaSnRK1 O/E increase the AGPase activity suggesting the direct regulation of rate limiting enzyme AGPase involved in starch biosynthesis. Furthermore, in vitro and in vivo interaction assay reveal that TaSnRK1 interacts with AGPase large sub-unit. Overall, our findings indicate that TaSnRK1 plays role in starch biosynthesis by regulating AGPase activity. HighlightsO_LITaSnRK1 is Ser/Thr kinase in wheat and show dual localization in nucleus and cytoplasm. C_LIO_LIOverexpression of TaSnRK1 increases starch content and enlarges starch granules in Arabidopsis. C_LIO_LITaSnRK1 enhances AGPase activity thereby regulating starch biosynthesis. C_LIO_LITaSnRK1 directly interact with AGPase large subunit in vivo and in vitro. C_LI

molecular biology↗

bioRxiv2023

Analytical Method Development for Evaluation of Pharmacokinetics and Tissue Distribution of Thiourea-Based Antivirals through nLC/MS-MS

Thiourea-based antivirals are organosulfur chemical compounds. Due to their various medicinal uses, including antiviral, antioxidant, and anticancer properties, they are becoming more popular. In this study, pharmacokinetics, Metabolism, bioavailability, and distribution of thiourea derivatives to organs of rats. Thiourea derivatives, namely DSA-00, DSA-02, and DSA-09, exhibit characteristics similar to those of conventional drugs when evaluated in terms of pharmacokinetics, drug-likeness, and medicinal chemistry through in-silico analysis. Then a simple and sensitive analytical method was developed for quantified DSA-00, DSA-02, and DSA-09, using prednisolone as an internal standard (IS) and nano liquid chromatography tandem mass spectrometry (nLC-MS/MS). The plasma and tissue samples were preprocessing with acetonitrile before chromatographic separation by C18 column with isocratic elution using a mobile phase of water-methanol (30:70, v/v) at a flow rate of 0.6 mL/min. A triplequadrupole tandem mass spectrometer in multiple-reaction monitoring (MRM) scanning via an electrospray ionization (ESI) source functioning in negative and positive mode detection. For DSA-00, DSA-02, DSA-09 and, internal standard the optimized mass transition ion-pairs (m/z) for quantification were 297.2, 311.2, 309.09, and 361.19 respectively. Each analytic run required only 15 minutes between injections. The calibration curve for thiourea derivatives showed good linear regression coefficient (R2 >.99) over a range of 1.00-10000 pg/mL except DSA-09. The lower limit of quantification (LLOQ) was 1.00 ng/mL. The intra- and inter-day precisions were no more than 10.8%, and relative errors (RE) ranged from 0.5 to 5.98%. The validated method was effectively used to explore the pharmacokinetics of orally administrative thiourea derivatives in rats.

pharmacology and toxicology↗

bioRxiv2023

Safety Assessment and Evaluation of Novel Thiourea Derivatives as Antivirals

DSA-00 and its two derivatives (DSA-02 & DSA-09) are new thiourea derivatives that exhibit strong antiviral activity against hepatitis B virus comparable to Entecavir. Here these compounds were evaluated for in-vitro cytotoxicity and genotoxicity, and in vivo acute toxicity for their potential therapeutic use. The cytotoxicity of thiourea derivatives was assessed in HepG2 and HepG2.2.15 cells by MTT assay whereas their genotoxicity was measured by Ames II test. The acute toxicity study was carried out in the Sprague-Dawley rats by observing the following parameters: mortality, clinical symptoms, hematological parameters, urine and changes in animal body & organs weight, gross necropsy and histopathology. DSA-00, DSA-02, and DSA-09 were non-cytotoxic even at the 320M concentration with respective CC50 values of 329.6, 323.5, and 349.7 M. The Ames II test revealed that these molecules were non-mutagenic at a [~]1M concentration. The acute toxicity studies revealed LD50 values belong from the moderate range of toxicity of DSA-00, DSA-02 and DSA-09. Importantly, there were no abnormal change in body weight and organs weight. Moreover, no abnormal clinical signs such as hematological parameter, urinalysis, gross necropsy and or histopathological in any of the animals after receiving oral doses of thiourea derivatives. Thiourea derivatives DSA-00, DSA-02, and DSA-09 appear to have a moderate range of acute toxicity at dosages used and thus, appear to be generally safe. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=125 SRC="FIGDIR/small/546447v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@8c8abaorg.highwire.dtl.DTLVardef@e7bcb1org.highwire.dtl.DTLVardef@15446dorg.highwire.dtl.DTLVardef@3f5d7b_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical AbstractC_FLOATNO Illustration of the study design and the findings for each aspect of the study: in-vitro cytotoxicity (1), genotoxicity by the Ames test (2), and oral toxicity in rats (3). C_FIG

pharmacology and toxicology↗

bioRxiv2023

Reorganization of Pancreas Circadian Transcriptome with Aging

The evolutionarily conserved circadian system allows organisms to synchronize internal processes with 24-h cycling environmental timing cues, ensuring optimal adaptation. Like other organs, the pancreas function is under circadian control. Recent evidence suggests that aging by itself is associated with altered circadian homeostasis in different tissues which could affect the organs resiliency to aging-related pathologies. Pancreas pathologies of either endocrine or exocrine components are age-related. Whether pancreas circadian transcriptome output is affected by age is still unknown. To address this, here we profiled the impact of age on the pancreatic transcriptome over a full circadian cycle and elucidated a circadian transcriptome reorganization of pancreas by aging. Our study highlights gain of rhythms in the extrinsic cellular pathways in the aged pancreas and extends a potential role to fibroblast-associated mechanisms.

molecular biology↗

bioRxiv2023

A deep catalog of protein-coding variation in 985,830 individuals

Coding variants that have significant impact on function can provide insights into the biology of a gene but are typically rare in the population. Identifying and ascertaining the frequency of such rare variants requires very large sample sizes. Here, we present the largest catalog of human protein-coding variation to date, derived from exome sequencing of 985,830 individuals of diverse ancestry to serve as a rich resource for studying rare coding variants. Individuals of African, Admixed American, East Asian, Middle Eastern, and South Asian ancestry account for 20% of this Exome dataset. Our catalog of variants includes approximately 10.5 million missense (54% novel) and 1.1 million predicted loss-of-function (pLOF) variants (65% novel, 53% observed only once). We identified individuals with rare homozygous pLOF variants in 4,874 genes, and for 1,838 of these this work is the first to document at least one pLOF homozygote. Additional insights from the RGC-ME dataset include 1) improved estimates of selection against heterozygous loss-of-function and identification of 3,459 genes intolerant to loss-of-function, 83 of which were previously assessed as tolerant to loss-of-function and 1,241 that lack disease annotations; 2) identification of regions depleted of missense variation in 457 genes that are tolerant to loss-of-function; 3) functional interpretation for 10,708 variants of unknown or conflicting significance reported in ClinVar as cryptic splice sites using splicing score thresholds based on empirical variant deleteriousness scores derived from RGC-ME; and 4) an observation that approximately 3% of sequenced individuals carry a clinically actionable genetic variant in the ACMG SF 3.1 list of genes. We make this important resource of coding variation available to the public through a variant allele frequency browser. We anticipate that this report and the RGC-ME dataset will serve as a valuable reference for understanding rare coding variation and help advance precision medicine efforts.

genetics↗

bioRxiv2023

Identification of Mirror Repeats in Viral Genomes using FPCB Analysis

The majority of living domains consist of DNA as genetic material with the minor exception of viruses. The unique nature of every species determines by its unique pattern of genome or gene products. The genomic features become an evident example of evolutionary study also. Different types of repeat patterns are observed in genomes of living domains including human beings whose two third portion of the genome is repetitive. Among the varied type of repeat sequences Mirror Repeats (MR) play crucial roles at the genetic level in every species. The major focus of our research is on identification & to check the distribution of mirror repeat. For this, we employed a bioinformatics-based approach refer as FASTA PARALLEL COMPLEMENT BLAST (FPCB) to identify unique mirror repeat (MR) sequences in some selected viral genomes from three different categories (Animal, Plant & Human). The identified repeats vary in their length as well as found to be distributed throughout the selected viral genomes. The maximum no of MR were reported in the case of Dengue virus (229) & minimum is in the case of TMV (97). In the remaining selected viruses - HCV, HPV, HTLV-1, PVY, Rabies virus 178, 156, 175, 203 & 204 MR sequences were reported. These sequences can be utilized in many ways like in molecular diagnosis, drug delivery target as well as evolutionary study, etc. The present research also helps in the development of novel tools of bioinformatics to study mirror repeats and their functional perspective in the context of their occurrence in all domains.

bioinformatics↗

bioRxiv2023

Molecular mechanisms of coronary artery disease risk at the PDGFD locus

Platelet derived growth factor (PDGF) signaling has been extensively studied in the context of vascular disease, but the genetics of this pathway remain to be established. Genome wide association studies (GWAS) for coronary artery disease (CAD) have identified a risk locus at 11q22.3, and we have verified with fine mapping approaches that the regulatory variant rs2019090 and PDGFD represent the functional variant and putative functional gene. Further, FOXC1/C2 transcription factor (TF) binding at rs2019090 was found to promote PDGFD transcription through the CAD promoting allele. Employing a constitutive Pdgfd knockout allele along with SMC lineage tracing in a male atherosclerosis mouse model we mapped single cell transcriptomic, cell state, and lesion anatomical changes associated with gene loss. These studies revealed that Pdgfd promotes expansion, migration, and transition of SMC lineage cells to the chondromyocyte phenotype and vascular calcification. This is in contrast to protective CAD genes TCF21, ZEB2, and SMAD3 which we have shown to promote the fibroblast-like cell transition or perturb the pattern or extent of transition to the chondromyocyte phenotype. Further, Pdgfd expressing fibroblasts and pericytes exhibited greater expression of chemokines and leukocyte adhesion molecules, consistent with observed increased macrophage recruitment to the plaque. Despite these changes there was no effect of Pdgfd deletion on SMC contribution to the fibrous cap or overall lesion burden. These findings suggest that PDGFD mediates CAD risk through promoting SMC expansion and migration, in conjunction with deleterious phenotypic changes, and through promoting an inflammatory response that is primarily focused in the adventitia where it contributes to leukocyte trafficking to the diseased vessel wall.

genetics↗

bioRxiv2022

CHRONO participates in multi-modal repression of circadian transcriptional complexes

The mammalian protein CHRONO is a rhythmically expressed repressor of the circadian transcriptional activator complex CLOCK:BMAL1, and was proposed to be a novel component of the circadian clock. However, lack of specific mechanistic understanding of the activity and function of CHRONO meant that its role within the circadian machinery was opaque. Here we fill this knowledge gap, confirming an evolutionarily conserved minimal repressive domain (MRD) of CHRONO that interacts with specific regions in the BMAL1 C-terminal transactivation domain (TAD) to repress CLOCK:BMAL1 activity. Notably, this binding region overlaps with the binding site for the repressor CRY and coactivators CBP/p300, with CHRONO capable of competing with both of these classical regulators of BMAL1 for TAD binding, highlighting CHRONO as a direct regulator of BMAL1 function. Additionally, we investigate the interaction between CHRONO and the major circadian repressor, PERIOD2 (PER2). We show that CHRONO reduces PER2 stability through interaction between the CHRONO C-terminus and the Casein Kinase 1 (CK1)-binding domain of PER2. This results in competition between CHRONO and CK1 for binding at this site on PER2, with CHRONO binding inhibiting CK1 phosphorylation of PER2 at the stabilising S662 residue. Taken together, these data show a more substantive and complex role for CHRONO in molecular circadian timekeeping than previously posited, suggesting that CHRONO acts to fine-tune cellular timekeeping by modulating multiple protein-protein interactions that are critical for maintenance of circadian rhythmicity.

biochemistry↗

bioRxiv2022

Dehydration alters transcript levels in the midgut, likely facilitating rapid rehydration

The mosquito midgut is an important site for bloodmeal regulation while also acting as a primary site for pathogen exposure within the mosquito. Recent studies show that exposure to dehydrating conditions alters mosquito bloodfeeding behaviors as well as post-feeding regulation, likely altering how pathogens interact with the mosquito. Unfortunately, few studies have explored the underlying dynamics between dehydration and bloodmeal utilization, and the overall impact on disease transmission dynamics remains veiled. In this study, we find that dehydration-based feeding in the yellow fever mosquito, Aedes aegypti, prompts alterations to midgut gene expression, as well as subsequent physiological factors involving water control and post-bloodfeeding (pbf) regulation. Altered expression of ion transporter genes in the midgut of dehydrated mosquitoes and rapid reequilibration of hemolymph osmolality after a bloodmeal indicate an ability to expedite fluid and ion processing. These alterations ultimately indicate that female A. aegypti employ mechanisms to ameliorate the detriments of dehydration by imbibing a bloodmeal, providing an effective avenue for rehydration. Continued research into bloodmeal utilization and the resulting effects on arthropod-borne transmission dynamics becomes increasingly important as drought prevalence is increased by climate change.

physiology↗

bioRxiv2022

CROP-Seq: a single-cell CRISPRi platform for characterizing candidate genes relevant to metabolic disorders in human adipocytes

ObjectiveCROP-Seq combines gene silencing using CRISPR interference (CRISPRi) with single-cell RNA sequencing (scRNA-Seq) to conduct a functional reverse genetic screen of novel gene targets associated with adipocyte differentiation or function, with single-cell transcriptomes as the readout. MethodsWe created a human preadipocyte SGBS cell line with stable expression of KRAB-dCas9 for CRISPRi-mediated gene knock-down. This line was transduced with a lentiviral library of sgRNAs targeting 6 genes of interest (3 sgRNAs / gene, 18 sgRNAs), 6 positive control genes (3 sgRNAs / gene, 18 sgRNAs), and non-targeting control sgRNAs (4 sgRNAs). Transduced cells were selected and differentiated, and individual cells were captured using microfluidics at day 0, 4 and 8 of adipogenic differentiation. Next, expression and sgRNA libraries were created and sequenced. Bioinformatic analysis of resulting scRNA-Seq expression data was used to determine the effects of gene knock-down and the dysregulated pathways, and to predict cellular phenotypes. ResultsSingle-cell transcriptomes obtained from SGBS cells following CRISPRi recapitulate different states of differentiation from preadipocytes to adipocytes. We confirmed successful knock-down of targeted genes. Transcriptome-wide changes were observed for all targeted genes, with over 400 differentially expressed genes identified per gene at least at one timepoint. Knock-down of known adipogenesis regulators PPARG and CEBPB inhibited adipogenesis. Gene set enrichment analyses revealed molecular processes for adipose tissue differentiation and function for novel genes. MAFF knock-down led to a downregulation of transcriptional response to proinflammatory cytokine TNF- in preadipocytes. TIPARP knock-down resulted in an increase in the expression of a beiging marker UCP1 at D8 of adipogenesis. ConclusionsThe CROP-Seq system in SGBS cells can determine the consequences of target gene knock-down at the transcriptome level. This powerful, hypothesis-free tool can identify novel regulators of adipogenesis, preadipocyte and adipocyte function associated with metabolic disease. HighlightsO_LICRISPR interference screen coupled with single-cell RNA sequencing (CROP-Seq) C_LIO_LIParallel screening of 12 genes in human SGBS adipocytes and preadipocytes C_LIO_LIUncovered novel regulators of adipogenesis and adipocyte function C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/497796v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@1ee34b6org.highwire.dtl.DTLVardef@1c6ba8aorg.highwire.dtl.DTLVardef@fa89org.highwire.dtl.DTLVardef@403966_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2022

Penetratin inhibits α-synuclein fibrillation and improves locomotor functions in mice model of Parkinsons disease

Parkinsons disease (PD) is the second most common neurodegenerative disease. The presence of lewy bodies, primarily consisting of -synuclein (-syn) aggregates is one of the common features seen in the substantia nigra region of the brain in PD patients. The disease remains incurable and only symptomatic relief is available. We screened various cell-penetrating peptides and reveal that penetratin is a potent inhibitor of -syn aggregation in-vitro, and significantly improved locomotor coordination in mice models of PD in-vivo. The peptide inhibits -syn aggregation in vitro as well as in yeast, and C.elegans models. We further made a cyclic derivative of penetratin by disulfide coupling of N- and C-terminal cysteine residues. Both penetratin and its cyclized derivative interact with -syn. NMR studies show that both linear as well as cyclic derivative interact at the acidic C-terminal tail of the protein. Similar to penetratin, its cyclic derivative inhibited -syn aggregation in the C.elegans model of Parkinsons disease, and also improved worm motility. Molecular Dynamics studies show that penetratin interacts with -synuclein and prevents its conformational transition from disordered into {beta}-sheet rich structure. The therapeutic efficacy of penetratin was further confirmed in a transgenic mice model of the disease, wherein penetratin treatment over a period of 90 days improved locomotor coordination, and halted disease progression. Overall, the present work provides a potent therapeutic agent that could be further explored in the management of PD.

neuroscience↗

bioRxiv2022

The epigenomic landscape of single vascular cells reflects developmental origin and identifies disease risk loci

Vascular sites have distinct susceptibility to atherosclerosis and aneurysm, yet the biological underpinning of vascular site-specific disease risk is largely unknown. Vascular tissues have different developmental origins that may influence global chromatin accessibility, and understanding differential chromatin accessibility, gene expression profiles, and gene regulatory networks (GRN) on single cell resolution may give key insight into vascular site-specific disease risk. Here, we performed single cell chromatin accessibility (scATACseq) and gene expression profiling (scRNAseq) of healthy adult mouse vascular tissue from three vascular sites, 1) aortic root and ascending aorta, 2) brachiocephalic and carotid artery, and 3) descending thoracic aorta. Through a comprehensive analysis at single cell resolution, we discovered key regulatory enhancers to not only be cell type, but vascular site specific in vascular smooth muscle (SMC), fibroblasts, and endothelial cells. We identified epigenetic markers of embryonic origin with differential chromatin accessibility of key developmental transcription factors such as Tbx20, Hand2, Gata4, and Hoxb family members and discovered transcription factor motif accessibility to be cell type and vascular site specific. Notably, we found ascending fibroblasts to have distinct epigenomic patterns, highlighting SMAD2/3 function to suggest a differential susceptibility to TGF{beta}, a finding we confirmed through in vitro culture of primary adventitial fibroblasts. Finally, to understand how vascular site-specific enhancers may regulate human genetic risk for disease, we integrated genome wide association study (GWAS) data for ascending and descending aortic dimension, and through using a distinct base resolution deep learning model to predict variant effect on chromatin accessibility, ChromBPNet, to predict variant effects in SMC, Fibroblasts, and Endothelial cells within ascending aorta, carotid, and descending aorta sites of origin. We reveal that although cell type remains a primary influence on variant effects, vascular site modifies cell type transcription and highlights genomic regions that are enriched for specific TF motif footprints -- including MEF2A, SMAD3, and HAND2. This work supports a paradigm that the epigenomic and transcriptomic landscape of vascular cells are cell type and vascular site-specific and that site-specific enhancers govern complex genetic drivers of disease risk.

genomics↗

bioRxiv2022

A visual atlas of genes tissue-specific pathological roles

Dysregulation of a genes function, either due to mutations or impairments in regulatory networks, often triggers pathological states in the affected tissue. Comprehensive mapping of these apparent gene-pathology relationships is an ever daunting task, primarily due to genetic pleiotropy and lack of suitable computational approaches. With the advent of high throughput genomics platforms and community scale initiatives such as the Human Cell Landscape (HCL) project [1], researchers have been able to create gene expression portraits of healthy tissues resolved at the level of single cells. However, a similar wealth of knowledge is currently not at our finger-tip when it comes to diseases. This is because the genetic manifestation of a disease is often quite heterogeneous and is confounded by several clinical and demographic covariates. To circumvent this, we mined ~18 million PubMed abstracts published till May 2019 and selected ~6.1 million of them that describe the pathological role of genes in different diseases. Further, we employed a word embedding technique from the domain of Natural Language Processing (NLP) to learn vector representation of entities such as genes, diseases, tissues, etc., in a way such that their relationship is preserved in a vector space. Notably, Pathomap, by the virtue of its underpinning theory, also learns transitive relationships. Pathomap provided a vector representation of words indicating a possible association between DNMT3A/BCOR with CYLD cutaneous syndrome (CCS). The first manuscript reporting this finding was not part of our training data. Key pointsO_LIWe mined ~18 million PubMed abstracts to extract latent knowledge pertaining to tissue specific pathological roles of genes. C_LIO_LIWe found well-defined gene modules implicated in disease pathogenesis in anatomically proximal tissues. C_LIO_LIWe demonstrated an ahead of time discovery of the association between DNMT3A/BCOR with CYLD cutaneous syndrome (CCS), as a knowledge synthesis use-case. C_LI

bioinformatics↗

bioRxiv2021

Pre-implantation mouse embryo movement under hormonally altered conditions

Precise regulation of embryo movement is crucial to successful implantation, but the role of ovarian hormones in this process is not understood. We ascertain the effects of altered hormonal environment on embryo movement using two delayed implantation models: Natural lactational Diapause (ND), a naturally occurring alternate model of pregnancy, and Artificially induced Diapause (AD), a laboratory version of ND. Our previous work suggests that embryos in a natural pregnancy (NP) first display unidirectional clustered embryo movement, followed by bidirectional scattering and spacing movement. In contrast, in the ND model, embryos are present as clusters near the oviductal-uterine junction for ~24-hours longer than NP, followed by locations consistent with a unidirectional scattering and spacing movement. Intriguingly, the AD model closely resembles embryo location in NP and not ND. Further, unlike the popular paradigm of reduced estrogen (E2) levels in diapause E2 levels are comparable across NP, ND, and AD, while progesterone (P4) levels are reduced in ND and highly increased in AD when compared to NP. Exogenous administration of E2 or P4 modifies the unidirectional clustered embryo movement, while E2 treatment causes a reduction in P4 and affects the bidirectional phase of embryo movement. Taken together, our data suggest embryo movement can be modulated by both P4 and E2. Understanding natural hormonal adaptation in diapause provides an opportunity to determine key players regulating embryo movement and implantation success. This knowledge can be leveraged to understand pregnancy survival and implantation success in hormonally altered conditions in the clinic.

developmental biology↗