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Vijayan, K.

Publications and source records attributed to Vijayan, K..

8 recordsLinked to original sources

Genome-scale prediction of context-specific synthetic lethality beyond protein interaction networks

Identifying synthetic lethal (SL) interactions offers a principled framework for discovering disease-specific therapeutic targets. However, current machine learning approaches heavily rely on curated protein-protein interaction networks. Because these networks cover only [~]7,500 proteins, they severely restrict the search space of human gene pairs and introduce systematic biases toward well-characterized genes. To circumvent these limitations, we developed SLxGO, a network-independent machine learning framework that predicts SL interactions directly from semantic representations of Gene Ontology annotations encoded via BioBERT-derived embeddings. Benchmarked across multiple cross-validation schemes against eight state-of-the-art methods, SLxGO consistently achieved superior predictive ranking performance, maintaining robustness under cold-start conditions for previously unseen genes. Integrating cell line-specific transcriptional profiles extended this framework to context-dependent SL prediction across six distinct cell lines. Notably, we experimentally confirmed a context-specific EFNA1-SLC29A1 SL interaction in HeLa cells, alongside synergistic pharmacological validation of an ACVR1-SLC29A1 vulnerability. All predictions are hosted on SLiGO, an open-access database encompassing 30 million human gene pairs, establishing a comprehensive, genome-scale resource for context-specific vulnerability mapping across the human interactome.

systems biology↗

A Comparative Chemical-Genetic Screen Reveals Divergent Roles for Host ALK2 Signaling Across Intracellular Bacterial Niches

Diverse vacuolar architectures present unique signaling challenges for intracellular bacteria, yet whether distinct niches share host requirements remains unclear. Because host kinases coordinate these complex cellular responses, we performed a comparative chemical-genetic screen of Coxiella burnetii, Chlamydia trachomatis, and Salmonella enterica. The screen revealed that C. burnetii is uniquely dependent on host kinase pathways. Deconvolution of these inhibitor profiles identified the bone morphogenetic protein (BMP) type I receptor, ALK2, as a critical regulatory checkpoint. While C. burnetii activates ALK2-mediated phospho-SMAD1/5/9 signaling to support replication, C. trachomatis actively suppresses this cascade. Mechanistically, ALK2 functions upstream of TFEB nuclear translocation and LAMP1 recruitment, driving the lysosomal biogenesis required to sustain the phagolysosome-like niche of C. burnetii while disrupting the non-lysosomal inclusion of C. trachomatis. Consequently, targeting ALK2 switches replication outcomes, demonstrating how distinct niches implement opposing strategies to exploit a single host signaling node.

microbiology↗

Identification of potent and selective N-myristoyltransferase inhibitors of Plasmodium vivax liver stage hypnozoites and schizonts

New drugs targeting multiple stages of the malaria-causing parasite, Plasmodium, are needed to reduce and eliminate malaria worldwide. N-Myristoyltransferase (NMT) is an essential eukaryotic enzyme, and a validated chemically tractable drug target for malaria. Previous efforts have failed to target NMT owing to the low selectivity for the Plasmodium enzyme compared with human NMTs. Herein, we applied a structure-guided approach using previously reported NMT inhibitors as scaffolds to develop a new generation of Plasmodium vivax NMT (PvNMT) targeting compounds. We report a series of compounds with IC50 values in the nM range and an order of magnitude improved selectivity to Plasmodium NMT over human NMT (HsNMT). X-ray co-crystallization of PvNMT with a representative lead compound, 12b, supported the prevailing hypothesis that a conformational difference in a key tyrosine residue of PvNMT and HsNMT drives the selectivity between these enzymes. The compounds were triaged based on their selectivity for PvNMT. They significantly decreased P. falciparum blood-stage parasite load, with IC50 values ranging from 0.36 M to 1.25 M. The compounds exhibited a dose-dependent inhibition of P. vivax liver stage schizont and hypnozoite infection, consistently, in three different P. vivax isolates with IC50 values ranging from 2.2 M to 6 M and from 1.2 M to 12 M. Our data provide evidence that NMT inhibitors could be multistage antimalarials, targeting both dormant and developing liver stage parasites, which is essential for malaria elimination. One Sentence SummaryPotent and selective N-myristoyltransferase inhibitors of Plasmodium vivax hypnozoites and schizonts were synthesized and tested.

pharmacology and toxicology↗

Temporally resolved kinase regulatory networks control endothelial barrier integrity

Vascular leak is a common disease complication, yet the signaling networks regulating barrier integrity are incompletely understood. We developed a novel methodology, Temporally REsolved KInase Network Generation (TREKING), which combines a 28-kinase inhibitor screen with machine learning and network reconstruction to build time-resolved, functional phosphosignaling networks. We demonstrated the utility of TREKING for identifying pathways mediating barrier integrity following thrombin stimulation with or without tumor necrosis factor (TNF) activation in brain endothelial cells. TREKING assigned distinct barrier phenotypes to mitogen-activated protein kinase (MAPK) pathways and revealed a condition-specific MAPKAPK2/MK2 switch kinase pathway with early barrier-disruptive activity in both inflammatory conditions, but late barrier-restorative activity exclusively in the absence of TNF pre-conditioning. MAPKAPK2/MK2 was activated with expected distinct kinetics under the two inflammatory conditions and late activation was linked to a MAP3K20/ZAK-MAPK14/p38-MAPKAPK2/MK2 pathway. Beyond MAPKs, TREKING predicts extensive interconnected networks that control barrier integrity and is a tool for dissecting complex temporal phosphosignaling networks across biological systems.

systems biology↗

Germinal center activity and B cell maturation promote protective antibody responses against Plasmodium pre-erythrocytic infection

Blocking Plasmodium, the causative agent of malaria, at the asymptomatic pre-erythrocytic stage would abrogate disease pathology and prevent transmission. Rodent-infectious species of Plasmodium such as P. yoelii (Py) serve as key tools to study vaccine efficacy and disease biology in immune-competent experimental animals. Here we evaluated the differences in vaccine-elicited humoral immunity in two widely used, and vastly diverged, inbred mouse strains, BALB/cJ and C57BL/6J, and identified immunological factors associated with protection. We vaccinated with Py circumsporozoite protein (CSP), the major surface antigen on the sporozoite, and evaluated protective efficacy after mosquito bite challenge. Vaccination achieved 60% sterile protection and otherwise delayed blood stage patency in BALB/cJ mice, whereas; all C57BL/6J mice were infected similar to controls. Interestingly, protection was mediated by antibodies, and could be passively transferred from immunized BALB/cJ mice into naive C57BL/6J. Dissection of the underlying immunological features of protection revealed early deficits in antibody titers and polyclonal avidity in C57BL/6J mice. Additionally, PyCSP-vaccination in BALB/cJ induced a significantly higher proportion of antigen-specific B-cells and class-switched memory B-cell (MBCs) populations than in C57BL/6J mice. Strikingly, C57BL/6J mice also had markedly fewer germinal center experienced, CSP-specific class-switched MBCs compared to BALB/cJ mice. Analysis of the IgG {gamma} chain repertoires by next generation sequencing in PyCSP-specific memory B-cell repertoires also revealed higher somatic hypermutation rates in BALB/cJ mice than in C57BL/6J mice. These findings indicate that BALB/cJ mice achieved higher levels of B cell maturation in response to vaccination with PyCSP, which likely enabled the development of protective antibody responses. Overall, our study indicates that germinal center activity and B cell maturation are key processes in the development of vaccine-elicited protective antibodies against CSP.

immunology↗

Antibody interference by a non-neutralizing antibody abrogates humoral protection against Plasmodium liver stage

Both subunit and attenuated whole sporozoite vaccination strategies against Plasmodium infection have shown promising initial results in malaria-naive westerners but exhibited less efficacy in malaria-exposed individuals in endemic areas. It has been hypothesized that preexisting immunity to malaria represents a significant roadblock to the development of a protective vaccine. Here, we demonstrate proof-of-concept that non-neutralizing antibodies (nNAb) can directly interfere with protective anti-PyCSP humoral responses. We developed and characterized a novel monoclonal antibody, RAM1, against the P. yoelii sporozoite major surface antigen, circumsporozoite protein (CSP). Unlike the canonical PyCSP repeat domain binding and neutralizing antibody (NAb) 2F6, RAM1 does not inhibit sporozoite traversal or entry of hepatocytes in vitro. Though 2F6 and RAM1 bind non-overlapping regions of the CSP-repeat domain, pretreatment with RAM1 abrogated 2F6s capacity to block sporozoite traversal and invasion in vitro. Importantly, RAM1 reduced the efficacy of the polyclonal humoral response against CSP in vivo, paralleling the observed reduced efficacy of RTS,S in malaria-exposed populations. Taken together, our data demonstrate the interference of non-neutralizing antibodies with the efficacy of NAbs and may impact the efficacy of anti-CSP vaccines in malaria-exposed individuals.

immunology↗

A Genome-wide CRISPR-Cas9 Screen Identifies Host Factors Essential for Optimal Plasmodium Liver Stage Development.

Prior to initiating symptomatic malaria, a single Plasmodium sporozoite infects a hepatocyte and develops into thousands of merozoites, in part by scavenging host resources. We show that host microtubules dynamically reorganize around the developing liver stage (LS) parasite. Using a genome-wide CRISPR-Cas9 screen, we identified host regulators of cytoskeleton organization, vesicle trafficking, ER/Golgi stress and lipid biogenesis that regulate Plasmodium LS development. These novel regulators of infection, including Centromere Protein J (CENPJ), led us to interrogate how microtubule organizing centers (MTOCs) are regulated during infection. Foci of {gamma}-tubulin localized to the parasite periphery; depletion of CENPJ exacerbated this re-localization and increased infection. Further, we show that the Golgi acts as a non-centrosomal MTOC by organizing {gamma}-tubulin and stimulating microtubule nucleation at the parasite periphery. Collectively, we show that the Plasmodium LS recruits the host Golgi to form MT mediated conduits along which host organelles are recruited to the PVM, to support liver stage development. Our findings suggest many host-targeted pharmacological inhibitors may inhibit LS infection.

cell biology↗

Plasmodium secretion induces hepatocyte lysosome exocytosis and promotes parasite entry

The invasion of a suitable host hepatocyte by Plasmodium sporozoites is an essential step in malaria infection. We demonstrate that in infected hepatocytes, lysosomes are redistributed away from the nucleus, and surface exposure of lysosomal-associated membrane protein (LAMP1) is increased. Lysosome exocytosis in infected cells occurs independently of sporozoite traversal. Instead, a sporozoite-secreted factor is sufficient for the process. Knockdown of the SNARE proteins involved in lysosome-plasma membrane fusion reduces lysosome exocytosis and Plasmodium infection. In contrast, promoting fusion between the lysosome and plasma membrane dramatically increases infection. Our work demonstrates new parallels between Plasmodium sporozoite entry of hepatocytes and infection by the excavate pathogen, Trypanosoma cruzi and raises the question of whether convergent evolution has shaped host cell invasion by divergent pathogens.

cell biology↗