Biology subjects

Muneer, A.

Publications and source records attributed to Muneer, A..

4 recordsLinked to original sources

bioRxiv2024

A dynamin-like protein in the human malaria parasite plays an essential role in mitochondrial homeostasis and fission during asexual blood stages

Malaria parasite harbors a single mitochondrion and its proper segregation during the parasite multiplication is crucial for propagation of the parasite within the host. Mitochondrial fission machinery consists of a number of proteins that associate with mitochondrial membrane during segregation. Here, we have identified a dynamin-like protein in P. falciparum, PfDyn2, and deciphered its role in mitochondrial division, segregation and homeostasis. GFP targeting approach combined with high resolution microscopy studies showed that the PfDyn2 associates with mitochondrial membrane to form a clip/hairpin loop like structure around it at specific sites during mitochondrial division. The C-terminal degradation tag mediated inducible knock-down (iKD) of PfDyn2 resulted in significant inhibition of parasite growth. PfDyn2-iKD hindered mitochondrial development and functioning, decreased mtDNA replication, and induced mitochondrial oxidative-stress, ultimately causing parasite death. Further, treatment of parasites with dynamin specific inhibitors disrupted the recruitment of PfDyn2 on the mitochondria, blocked mitochondrial development, and induced oxidative stress. Regulated overexpression of a phosphorylation mutant of PfDyn2 (Ser-612-Ala) had no effect on the recruitment of PfDyn2 on the mitochondria; normal mitochondrial division and parasite growth showed that phosphorylation/dephosphorylation of this conserved serine residue (Ser612) may not be responsible for regulating recruitment of PfDyn2 to the mitochondrion. Overall, we show essential role of PfDyn2 in mitochondrial dynamics and fission as well as in maintaining its homeostasis during asexual cycle of the parasite.

cell biology↗

bioRxiv2024

Targeting G9a translational mechanism of SARS-CoV-2 pathogenesis for multifaceted therapeutics of COVID-19 and its sequalae

By largely unknown mechanism(s), SARS-CoV-2 hijacks the host translation apparatus to promote COVID-19 pathogenesis. We report that the histone methyltransferase G9a noncanonically regulates viral hijacking of the translation machinery to bring about COVID-19 symptoms of hyperinflammation, lymphopenia, and blood coagulation. Chemoproteomic analysis of COVID-19 patient peripheral mononuclear blood cells (PBMC) identified enhanced interactions between SARS-CoV-2-upregulated G9a and distinct translation regulators, particularly the N6-methyladenosine (m6A) RNA methylase METTL3. These interactions with translation regulators implicated G9a in translational regulation of COVID-19. Inhibition of G9a activity suppressed SARS-CoV-2 replication in human alveolar epithelial cells. Accordingly, multi-omics analysis of the same alveolar cells identified SARS-CoV-2-induced changes at the transcriptional, m6A-epitranscriptional, translational, and post-translational (phosphorylation or secretion) levels that were reversed by inhibitor treatment. As suggested by the aforesaid chemoproteomic analysis, these multi-omics-correlated changes revealed a G9a-regulated translational mechanism of COVID-19 pathogenesis in which G9a directs translation of viral and host proteins associated with SARS-CoV-2 replication and with dysregulation of host response. Comparison of proteomic analyses of G9a inhibitor-treated, SARS-CoV-2 infected cells, or ex vivo culture of patient PBMCs, with COVID-19 patient data revealed that G9a inhibition reversed the patient proteomic landscape that correlated with COVID-19 pathology/symptoms. These data also indicated that the G9a-regulated, inhibitor-reversed, translational mechanism outperformed G9a-transcriptional suppression to ultimately determine COVID-19 pathogenesis and to define the inhibitor action, from which biomarkers of serve symptom vulnerability were mechanistically derived. This cell line-to-patient conservation of G9a-translated, COVID-19 proteome suggests that G9a inhibitors can be used to treat patients with COVID-19, particularly patients with long-lasting COVID-19 sequelae.

immunology↗

bioRxiv2022

Dual role of an essential HtrA2/Omi protease in the human malaria parasite: maintenance of mitochondrial homeostasis and induction of apoptosis like cell death under cellular stress

HtrA family of serine protease is known to play role in mitochondrial homeostasis as well as in the programmed cell death. Mitochondrial homeostasis and metabolism are crucial for survival and propagation of malaria parasite within the host. Here we have functionally characterized a Plasmodium falciparum HtrA2 (PfHtrA2) protein, which harbours trypsin like protease activity that can be inhibited by its specific inhibitor, ucf-101. Transgenic parasite line was generated, using HA-glmS C-terminal tagging approach, for localization as well as for inducible knockdown of PfHtrA2. The PfHtrA2 was localized in the parasite mitochondrion during asexual life cycle. Genetic ablation of PfHtrA2 caused significant parasite growth inhibition, decreased replication of mtDNA, increased mitochondrial ROS production, caused mitochondrial fission/fragmentation, and hindered parasite development. However, ucf-101 treatment had no effect on the parasite growth, suggesting non-protease/chaperone role of PfHtrA2 in the parasite. Under cellular stress conditions, inhibition of PfHtrA2 by ucf-101 reduced activation of the caspase like protease as well as parasite cell death, suggesting involvement of protease activity of PfHtrA2 in apoptosis like cell death in the parasite. Under these cellular stress conditions, the PfHtrA2 gets processed but remains localized in the mitochondrion, suggesting that it acts within the mitochondrion by cleaving intra-mitochondrial substrate(s). This was further supported by trans-expression of PfHtrA2 protease domain in the parasite cytosol, which was unable to induce any cell death in the parasite. Overall, we show specific role of PfHtrA2 in maintaining mitochondrial homeostasis as well as in regulating the stress induced cell death.

cell biology↗

bioRxiv2020

Novel gene-specific translation mechanism of dysregulated, chronic inflammation reveals promising, multifaceted COVID-19 therapeutics

Hyperinflammation and lymphopenia provoked by SARS-CoV-2-activated macrophages contribute to the high mortality of Coronavirus Disease 2019 (COVID-19) patients. Thus, defining host pathways aberrantly activated in patient macrophages is critical for developing effective therapeutics. We discovered that G9a, a histone methyltransferase that is overexpressed in COVID-19 patients with high viral load, activates translation of specific genes that induce hyperinflammation and impairment of T cell function or lymphopenia. This noncanonical, pro-translation activity of G9a contrasts with its canonical epigenetic function. In endotoxin-tolerant (ET) macrophages that mimic conditions which render patients with pre-existing chronic inflammatory diseases vulnerable to severe symptoms, our chemoproteomic approach with a biotinylated inhibitor of G9a identified multiple G9a-associated translation regulatory pathways that were upregulated by SARS-CoV-2 infection. Further, quantitative translatome analysis of ET macrophages treated progressively with the G9a inhibitor profiled G9a-translated proteins that unite the networks associated with viral replication and the SARS-CoV-2-induced host response in severe patients. Accordingly, inhibition of G9a-associated pathways produced multifaceted, systematic effects, namely, restoration of T cell function, mitigation of hyperinflammation, and suppression of viral replication. Importantly, as a host-directed mechanism, this G9a-targeted, combined therapeutics is refractory to emerging antiviral-resistant mutants of SARS-CoV-2, or any virus, that hijacks host responses.

systems biology↗