Biology subjects

Chitalia, V.

Publications and source records attributed to Chitalia, V..

6 recordsLinked to original sources

bioRxiv2025

Tryptophan metabolism reprogramming contributes to the prothrombotic milieu in mice and humans infected with SARS-CoV-2

SARS-CoV-2 infection disturbs the coagulation balance in the blood, triggering thrombosis and contributing to organ failure. The role of prothrombotic metabolites in COVID-19-associated coagulopathy remains elusive. Leveraging K18-hACE2 mice infected with SARS-CoV-2, we observed higher levels of the tryptophan metabolite, kynurenine, compared to controls. SARS-CoV-2 infected mice showed a significant upregulation of enzymes controlling Kynurenine biogenesis, such as indoleamine 2,3-dioxygenase (IDO-1) and tryptophan 2,3-dioxygenase levels in kidneys and liver, respectively, as well as changes in the enzymes involved in kynurenine catabolism, including kynurenine monooxygenase and kynurinase. Consistent with the agonistic role of these metabolites in Aryl Hydrocarbon Receptor (AHR) signaling, AHR activation and its downstream mediator, tissue factor (TF), a highly potent procoagulant factor, was observed in endothelial cells (ECs) of lungs and kidneys of infected mice. These findings were validated in humans, where compared to controls, sera of COVID-19 patients showed increased levels of Kynurenine, kynurenic acid, anthranilic acid, and quinolinic acid. Activation of the AHR-TF axis was noted in the kidneys and lungs of COVID-19 patients, and COVID-19 sera showed higher IDO-1 activity than controls. Levels of Kyn in COVID-19 patients correlated strongly with the TF-inducing activity of COVID-19 sera on ECs. A specific IDO-1 inhibitor or AHR inhibitor separately or in combination suppressed COVID-19 sera-induced TF activity in ECs. Together, we identified IDO-1 as upregulated by SARS-CoV-2 infection, resulting in augmented Kyn and its prothrombotic catabolites, thereby suggesting the Kyn-AHR-TF axis as possibly a new diagnostic and/or therapeutic target. Key pointsO_LISARS-CoV-2-infection upregulates kynurenine biogenesis in the liver and diminishes kynurenine catabolism in the lungs and kidneys. C_LIO_LIAn increase in kynurenine stimulates the AHR-TF axis in the microvasculature in COVID-19 patients, which is inhibited by pharmacological manipulation. C_LI

systems biology↗

bioRxiv2024

A murine model of cardiovascular-kidney-metabolic syndrome demonstrates compromised limb function in the ischemic hind limb

AbstractsO_ST_ABSBackgroundC_ST_ABSCardiovascular-Kidney-metabolic (CKM) syndrome is a public health problem involving > 90% of the US and results in premature CVD at a relatively preserved GFR. The molecular mediators of CKM are poorly understood, partly due to the lack of a reliable animal model. We set out to generate an animal model with renal and metabolic dysfunctions, using PAD as a CKM manifestation. MethodsA group of C57BL/6 mice was randomized into four groups-a normal diet (ND), a 0.2% adenine diet (AD, a CKD model), a high-fat diet (HFD, a metabolic model), and a combination of HFD+AD (a potential CKM model). Mice underwent a hind limb ischemia surgery. An array of structural (capillary density, soleus muscle evaluation), and functional assays were performed. ResultsCompared to ND mice, AD mice showed loss of weight (40%) and GFR (90%) (P<0.001). The HFD+AD mice had 23-50% higher weight and GFR than the AD group (P = 0.003). The kidneys of HFD+AD showed tubular atrophy, tubulointerstitial fibrosis, immune infiltration, glomerulomegaly, consistent with glomerular hyperperfusion, hypercholesterolemia, impaired glucose tolerance, and adipophilin in the liver, an early marker of hepatic steatosis, and myocardial fibrosis. Compared to ND mice, the AD and HFD+AD mice showed similar reductions in the hind limb perfusion ratios, microcapillary density, Type II muscle fibers, and increased muscle fibrosis, immune infiltration, and lowest cross-sectional muscle area. Compared to AD, HFD+AD mice showed a lower flux ratio and grip strength, all at a GFR double that of the AD group. ConclusionA combination of HFD+AD in mice displays features of CKD (loss of GFR, renal fibrosis), dysfunctional obesity (dyslipidemia, impaired glucose tolerance, hepatic steatosis and glomerulomegaly), and cardiovascular disease (myocardial fibrosis and PAD) at a higher GFR, consistent with the features of CKM. This model can be explored to probe the mechanisms of CKM syndrome.

pathology↗

bioRxiv2024

IGPR-1 is phosphorylated on the immunoreceptor tyrosine-based motif, stimulates AKT pathway and supports melanoma growth

Melanoma is a lethal form of skin cancer that impacts one out of every five Americans and ranks as the fifth most prevalent cancer among men and women in the United States. Immunoglobulin (Ig) and Proline-rich Receptor-1 (IGPR-1, also called TMIGD2/CD28H) is closely related to immune checkpoint, CD28/PDL1 family receptors. It controls important cellular processes including, immune cell regulation, cell-cell adhesion, mechanosensing, autophagy, and angiogenesis, and its activity is associated with multiple human malignancies. However, the role and signaling mechanism of IGPR-1 in melanoma remains largely undefined. Here, we report that IGPR-1 is mutated or upregulated in nearly 13% of melanoma and its pro-tumor signaling in melanoma cells is mediated by phosphorylation of immunoreceptor tyrosine-based activation motif (ITAM) tyrosine (Y222). IGPR-1 is phosphorylated at Y222 in human melanoma and cell culture. Phosphorylation of Y222 is context-dependent and is catalyzed by EGFR and Src kinase. Inhibition of EGFR by pharmacological and shRNA strategies inhibited phosphorylation of Y222, whereas stimulation with EGF promoted phosphorylation of Y222 in vivo and recombinant active EGFR catalyzed its phosphorylation in an in vitro kinase assay. In vivo co-immunoprecipitation and in vitro GST-pull-down assays demonstrated that phospho-Y222 facilitates the binding of IGPR-1 with the SH2 domain-containing proteins, SHC1 and SHP2. IGPR-1 stimulates multiple key signal transduction pathways relevant to tumorigenesis, including AKT, mTOR, and MAPK. Mutation of Y222 blocked IGPR-1-mediated activation of AKT and MAPK leading to inhibition of 3D-spheroid tumor growth. By investigating the immunoreceptor tyrosine-based motif signaling of IGPR-1, this study uncovers new findings that could have significant diagnostic and therapeutic implications for melanoma.

cancer biology↗

bioRxiv2020

CD209L/L-SIGN and CD209/DC-SIGN act as receptors for SARS-CoV-2 and are differentially expressed in lung and kidney epithelial and endothelial cells

As the COVID-19 pandemic continues to spread, investigating the processes underlying the interactions between SARS-CoV-2 and its hosts is of high importance. Here, we report the identification of CD209L/L-SIGN and the related protein CD209/DC-SIGN as receptors capable of mediating SARS-CoV-2 entry into human cells. Immunofluorescence staining of human tissues revealed prominent expression of CD209L in the lung and kidney epithelium and endothelium. Multiple biochemical assays using a purified recombinant SARS-CoV-2 spike receptor binding domain (S-RBD) or S1 encompassing both NTB and RBD and ectopically expressed CD209L and CD209 revealed that CD209L and CD209 interact with S-RBD. CD209L contains two N-glycosylation sequons, at sites N92 and N361, but we determined that only site N92 is occupied. Removal of the N-glycosylation at this site enhances the binding of S-RBD with CD209L. CD209L also interacts with ACE2, suggesting a role for heterodimerization of CD209L and ACE2 in SARS-CoV-2 entry and infection in cell types where both are present. Furthermore, we demonstrate that human endothelial cells are permissive to SARS-CoV-2 infection and interference with CD209L activity by knockdown strategy or with soluble CD209L inhibits virus entry. Our observations demonstrate that CD209L and CD209 serve as alternative receptors for SARS-CoV-2 in disease-relevant cell types, including the vascular system. This property is particularly important in tissues where ACE2 has low expression or is absent, and may have implications for antiviral drug development.

cell biology↗

bioRxiv2020

TMIGD1, a putative tumor suppressor, induces G2-M cell cycle checkpoint arrest in colon cancer cells

Colorectal cancer (CRC) is a leading non-familial cause of cancer mortality among men and women. Although various genetic and epigenetic mechanisms have been identified, the full molecular mechanisms deriving CRC tumorigenesis remains incompletely understood. In this study, we demonstrate that cell adhesion molecule transmembrane and immunoglobulin domain containing1 (TMIGD1) is highly expressed in mouse and human normal intestinal epithelial cells. We have developed TMIGD1 knockout mice and show that the loss of TMIGD1 in mice results in the development of adenomas in small intestine and colon. Additionally, the loss of TMIGD1 in mouse impaired intestinal epithelium brush border formation, junctional polarity and maturation. Mechanistically, TMIGD1 inhibits tumor cell proliferation, cell migration, arrests cell cycle at G2/M phase and induces expression of p21CIP1 (cyclin-dependent kinase inhibitor 1), and p27KIP1 (cyclin-dependent kinase inhibitor 1B) expression, key cell cycle inhibitor proteins involved in the regulation of the cell cycle. Moreover, we demonstrate that TMIGD1 is progressively downregulated in sporadic human CRC and correlates with poor overall survival. Our findings identify TMIGD1 as a novel tumor suppressor gene and provide insights into the pathogenesis of colorectal cancer and possibilities as a potential therapeutic target.

cancer biology↗

bioRxiv2019

Genomic Polymorphisms in Toxin-Antitoxin Systems and Identification of Novel Phylo-SNPs and Polymorphisms Associated with Drug Resistance/Susceptibility in Clinical Isolates of Mycobacterium tuberculosis from Mumbai, India

Toxin-antitoxin (TA) modules are one of the prominent determinants that triggers a persistent state aiding Mycobacterium tuberculosis evasion to host generated stresses. The 79 characterized and putative TA systems described in M. tuberculosis are dominated by the VapBC, MazEF, HigAB, RelBE and ParDE TA families, largely involved in persistence and cell arrest. Hence, there is a need to maintain and conserve the TA loci in the chromosome of the pathogen. It is essential to study the genomic differences of the TA systems in clinical isolates along with its association to drug susceptibility patterns and lineage. In the current study, the TA loci and their promoter sequences were analysed from the whole genome sequence data of 74 clinical isolates. Mykrobe Predictor was used for lineage identification and drug resistance predictions in the clinical isolates. Polymorphisms associated with 79.8% (63/79) TA systems were observed across 72 clinical isolates. Among the TA systems, the isolates had a varying number of polymorphisms localised primarily in the toxin genes (58.7%), antitoxin genes (40.7%) and chaperones (0.6%), due to Single Nucleotide Polymorphism (SNP) resulting in transition (67.3%), transversion or frameshift mutations. Our analysis suggests the presence of novel Phylo-SNPs by establishing high confidence association of specific lineages to polymorphisms in the TA systems. Notably, association of polymorphisms in Rv1838c-1839c (VapBC13), Rv3358-3357 (YefM/YoeB) and Rv0240-0239 (VapBC24) to Delhi/Central Asia lineage. The polymorphic loci of the 3 TA systems is localised in the antitoxin gene of the Delhi/Central Asia strains, with a resultant silent mutation. The assessment of correlation between TA polymorphisms and the drug resistance profile revealed correlation of SNPs in VapBC35 with drug resistant M. tuberculosis strains and SNPs in VapBC24, VapBC13 and YefM/YoeB to drug sensitive strains.

bioinformatics↗