Biology subjects

Zalavadia, A.

Publications and source records attributed to Zalavadia, A..

4 recordsLinked to original sources

bioRxiv2026

SETD3 ACTIN HISTIDINE METHYLTRANSFERASE REGULATES INTESTINAL EPITHELIAL BARRIER INTEGRITY AND MUCOSAL INFLAMMATION

Intestinal epithelial barrier is a key feature of the healthy gut, and disruption of this barrier is a driver of mucosal inflammation. Integrity of the intestinal epithelial barrier is controlled by tight junctions (TJs) and adherens junctions (AJs) associated with the underlying actin cytoskeleton. Posttranslational modifications of actins affect the cytoskeletal assembly and dynamics, however whether such modifications regulate epithelial barriers remains unknown. SETD3 methyltransferase methylates actins at the His73 residue, thereby enhancing filamentous (F)-actin polymerization and turnover. This study examines the role of SETD3 in regulating structure and function of normal intestinal epithelial barrier, as well as its involvement in barrier disruption during mucosal inflammation. siRNA mediated knockdown of SETD3 in DLD-1 and HCA-7 human intestinal epithelial cells (IEC) resulted in several functional and morphological cell abnormalities. These include increased permeability of the IEC barrier, diminished assembly of the perijunctional F-actin belt, increased cell size, and delayed TJ reassembly during calcium switch. Consistently, SETD3 knockout (KO) mice displayed increased intestinal permeability and decreased labeling intensity of apical {beta}-actin as compared to wildtype controls. Furthermore, SETD3 KO mice showed increased cell stemness and proliferation in colonic epithelium without defects in AJ/TJ assembly and secretory cell differentiation. In addition, SETD3 KO mice developed more severe disease symptoms during dextran sodium sulfate (DSS)-induced colitis, which were accompanied by accelerated mucosal erosion and increased macrophage, T cell and neutrophil infiltration into colonic tissue. Overall, our data suggests that SETD3 acts as a novel positive regulator of the intestinal epithelial barrier and plays a protective role during intestinal mucosal damage and inflammation.

cell biology↗

bioRxiv2025

Microbial metabolite 4-ethylphenylsulfate (4EPS) interacts with AT1R, reduces blood pressure and outcome of AngII-induced aortic aneurysm

BACKGROUNDPlasma accumulation of the gut microbial metabolite, 4-ethylphenylsulfate (4EPS), produced from dietary protein aromatic amino acids has been observed in correlative and associative studies of cardiovascular, renal, metabolic and neurological diseases. 4EPS level increases upon AngII infusion in mice. How 4EPS alters host physiology to contribute to progression of any disease state is currently unknown. METHODSTo test the hypothesis that 4EPS interferes with angiotensin binding to AT1R, we used multiple approaches: AT1R pharmacology, cell-signaling, ex vivo vascular contraction and a mouse model of angiotensin-induced aortic aneurysm (AA) disease. ApoE-null mice were fed high-fat diet and infused with AngII, or co-infused with 4EPS and Olmesartan. BP was recorded. At the end of infusion, aortas were assessed for severity of AA, contractile response and histopathology. To evaluate signaling associated with different AA outcomes plasma proteomics analysis was done. RESULTSIn vitro, 4EPS reduced the binding of angiotensin and Candesartan to AT1R and calcium signaling. Ex vivo, 4EPS decreased vasomotor response of the aorta to AngII. In vivo, 4EPS inhibited AngII-mediated increase of BP and reduced mortality from AA. Abdominal aorta remodeling in 4EPS+AngII co-infused mice showed an increase of elastin area and reduced thickening of intimal/medial layers. Plasma proteome analysis indicated significant change in actin-cytoskeletal signaling associated with reduced ERK1/2 and Filamin-A activation, and cell motility. CONCLUSIONSBenign antagonism of AT1R by 4EPS involves direct interaction with AT1R. Molecular mechanisms of 4EPS responsible for reduced AA associated mortality in mice are distinct from those of AT1R blocker, Olmesartan. GRAPHIC ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=123 HEIGHT=200 SRC="FIGDIR/small/635371v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@1a33049org.highwire.dtl.DTLVardef@b73071org.highwire.dtl.DTLVardef@cd5557org.highwire.dtl.DTLVardef@9dc63e_HPS_FORMAT_FIGEXP M_FIG C_FIG

pathology↗

bioRxiv2022

Ifit2 regulates murine-coronavirus spread to the spinal cord white matter and its associated myelin pathology

Ifit2, an interferon-induced protein with tetratricopeptide repeats 2, plays a critical role in restricting neurotropic murine {beta}-coronavirus RSA59 infection. RSA59 intracranial injection of Ifit2 deficient (-/-) compared to wild type (WT) mice results in impaired acute microglial activation, associated with reduced CX3CR1 expression, which consecutively limits migration of peripheral lymphocytes into the brain, leading to impaired virus control followed by severe morbidity and mortality. While the protective role of Ifit2 is established for acute viral encephalitis, less is known about its influence on demyelination during the chronic phase of RSA59 infection. Our current study demonstrates that Ifit2 deficiency causes extensive RSA59 viral spread throughout both the spinal cord grey and white matter and is associated with impaired CD4+ T cell infiltration. Cervical lymph nodes of RSA59 infected Ifit2-/- mice showed reduced activation of CD4+ T cells and impaired IFN{gamma} expression during acute encephalomyelitis. Furthermore, blood-brain-barrier integrity was preserved in the absence of Ifit2 as evidenced by integral, tight junction protein ZO-1 expression surrounding the meninges and blood vessels and decreased Texas red dye uptake. In contrast to WT mice exhibiting only sparse myelin loss, the chronic disease phase in Ifit2-/- mice was associated with severe demyelination and persistent viral load, even at low infection doses. Overall, our study highlights that Ifit2 provides antiviral functions by promoting acute neuroinflammation and thereby aiding virus control and limiting severe demyelination. Author SummaryThe role of interferons in providing protective immunity against viral spread and pathogenesis is well known. Interferons execute their function by inducing certain genes collectively called as interferon stimulated genes (ISGs) among which Interferon-induced protein with tetratricopeptide repeats 2, Ifit2, is known for restricting neurotropic viral replication and spread in the brain. So far, not much has been investigated about its role in viral spread to the spinal cord and its associated myelin pathology. Towards this our study using neurotropic murine-{beta}-coronavirus and Ifit2 deficient mice demonstrate that Ifit2 deficiency causes extensive viral spread throughout grey and white matter of spinal cord accompanied by impaired microglial activation and CD4+ T cell infiltration. Furthermore, infected Ifit2 deficient mice showed impaired activation of T cells in cervical lymph node and Blood-Brain-Barrier was relatively intact. Ifit2 deficient mice developed viral induced severe chronic neuroinflammatory demyelination accompanied by the presence of ameboid shaped phagocytotic microglia/macrophages.

neuroscience↗

bioRxiv2022

The MIF SNP rs755622 is a germline determinant of tumor immune activation in Glioblastoma

While immunotherapies have shown durable responses for multiple tumors, their efficacy remains limited in some advanced cancers, including glioblastoma. This may be due to differences in the immune landscape, as the glioblastoma microenvironment strongly favors immunosuppressive myeloid cells, which are linked to an elevation in immune-suppressive cytokines, including macrophage migration inhibitory factor (MIF). We now find that a single-nucleotide polymorphism (SNP) rs755622 in the MIF promoter associates with increased leukocyte infiltration in glioblastoma. Furthermore, we identified lactotransferrin expression as being associated with the rs755622 SNP, which could also be used as a biomarker for immune infiltrated tumors. These findings provide the first example in glioblastoma of a germline SNP that underlies differences in the immune microenvironment and identifies high lactotransferrin as a potential factor promoting immune activation.

cancer biology↗