Biology subjects

Prasad, N. R.

Publications and source records attributed to Prasad, N. R..

3 recordsLinked to original sources

bioRxiv2026

E3 ubiquitin ligase SYVN1 mediates K63-linked ubiquitination of DDX3X to activate Macrophage NLRP3 Inflammasome

DDX3X (DEAD box helicase 3, X linked) is a common and essential component for both stress granules and NLRP3 inflammasome assembly and their activation; however, the upstream cellular stress signals driving DDX3X to activate the contrasting cellular pathway remain unclear. We identified the pivotal role of the E3 ubiquitin ligase SYVN1(Synoviolin) as the upstream regulator of DDX3X and thereby controlling NLRP3 activation and stress granule assembly. We observed SYVN1 silencing in macrophages prevented both NLRP3 driven inflammation and stress granule formation. SYVN1 deficiency prevented LPS induced inflammatory lung injury and increased the survival rate of the mice. SYVN1 sustains DDX3X gene expression and promotes stimulus-dependent ubiquitination of DDX3X. Under inflammatory conditions, SYVN1 mediated 63 linked ubiquitination of DDX3X, a requirement for NLRP3 inflammasome activation. Conversely, stress conditions reduced K63 linked DDX3X ubiquitination in coordination with activity of the deubiquitinase OTUB1 (OTU domain-containing ubiquitin aldehyde-binding protein 1). Thus, the balance between SYVN1 and OTUB1 functioned to optimize DDX3X activity and activation of NLRP3 or stress granule. These findings show the upstream role of SYVN1 OTUB1 axis in integrating cellular stress signals to decide the cell fate and suggest that ubiquitination of DDX3X is a potential target for inflammasome driven inflammation.

immunology↗

bioRxiv2026

Innate Immune Function of Neutrophil Cytoplasts Generated Post-Vital NETosis

The migration of polymorphonuclear neutrophils (PMN) into the site of infection such as lungs during pneumonia is a canonical feature of innate immunity. Formation of neutrophil-derived extracellular traps (NETs), web-like strands of varying lengths comprising DNA, histones, elastase, and myeloperoxidase, is an important determinant of PMN-mediated innate immunity. NETs form in microvessels, entrap bacteria and effete matter, and dampen PMN-mediated inflammatory injury at specific sites. However, studies have largely focused on NET release secondary to lytic NETosis and lysis of PMN. Far less is known about vital NETosis occurring in the absence of PMN rupture. As vital NETosis is characterized by generation of anuclear PMN termed cytoplasts (PMNcyto), we addressed the function of PMNcyto as a critical determinant of PMN-mediated innate immunity. Studies were made in mice challenged with live Pseudomonas aeruginosa (PA) i.t. to induce fulminant pneumonia characterized by tissue injury in which we determined the role of generated PMNcyto population. Using Tomato Red (tDTomato) transgenic mice to mark PMN, we observed PA pneumonia induced PMN transmigration leading to PMNcyto generation in the airspace. In contrast, PMNcyto transmigration, was minimal. PMNcyto accumulating in lung tissue actively phagocytosed and killed PA. Instillation of ex vivo generated PMNcyto also prevented PA-induced inflammatory lung injury and reduced mortality as compared to control mice. We demonstrated that the salutary effects of PMNcyto required functional microchondria. Proteomic analysis revealed that PMNcyto retained bactericidal and ROS generating pathways, consistent with an intact plasma membrane. Genetic deletion of peptidyl arginine deaminase 4 (PAD4), which mediates histone citrullination and promotes NETosis, facilitates PMNcyto generation and thereby abrogated pneumonia-induced mortality. Thus, we have identified the crucial host defense function of PMNcyto generated post-vital NETosis, suggesting that PMNcyto hold promise as cell based anti-bacterial therapy in pneumonia.

immunology↗

bioRxiv2024

Immunologic comparisons of strain and induction method in an improved mouse model of intrauterine fibrosis

Intrauterine adhesions are growths of fibrotic tissue within the uterine cavity and can arise from a variety of tissue-damaging stimuli. Immune cells are known to mediate fibrotic responses, but specific mechanisms require further elucidation. Here, we compared intrauterine fibrosis development and immune responses across different mouse strains and induction methods. We aimed to identify a consistent and more clinically relevant mouse model of intrauterine fibrosis, whether immune responses differ in response to different stimuli, and which potential key immune cell populations are responsible for intrauterine fibrosis susceptibility. Intrauterine fibrosis induction methods were compared using surgical curettage or transcervically administered chemical (quinacrine) models. Measurements of tissue morphology and collagen gene expression indicate BALB/c mice are more susceptible than C57BL/6 mice to intrauterine fibrosis. In chemically induced BALB/c uterine tissues, gene expression and flow cytometry data show greater pro-inflammatory macrophage responses, implicating a possible role in fibrogenesis consistent with human intrauterine adhesion data. Findings from this study demonstrate the importance of mouse strain selection in studies of intrauterine adhesions. Furthermore, we show that a new hormone-synchronized, chemically induced mouse model can more uniformly and reliably provoke fibrotic tissue response. This model may allow for greater elucidation of mechanisms involved in intrauterine adhesion development, and exploratory therapeutic studies for treatment intervention.

bioengineering↗