Biology subjects

Rahman, M. M.

Publications and source records attributed to Rahman, M. M..

At least 37 records · Page 2Linked to original sources

bioRxiv2024

Bwa, an ortholog of alkaline ceramidase-ACER2, promotes intestinal stem cell proliferation through pro-inflammatory cytokine signaling in Drosophila melanogaster

Sphingolipids, including ceramides, are an important component of high-fat diets. These molecules can regulate fatty acid oxidation and intestinal stem cell proliferation, predisposing the gut to tumorigenesis. However, the molecular mechanisms involved in ceramide metabolism-mediated intestinal stem cell (ISC) proliferation and tumorigenesis are poorly understood. To understand how changes in sphingolipid metabolite flux affect intestinal stem cells, we manipulated the activities of each of the enzymes of the ceramide synthetic pathway using cell type-specific over-expression or depletion of the corresponding mRNAs in each intestinal cell type of the Drosophila midgut. We documented cell-autonomous and non-cell-autonomous effects, including alterations in cell size, number, differentiation, and proliferation. In our screen, the altered expression of several ceramide metabolism enzymes led to changes in ISC proliferation, cell sizes, and overall cellularity. Among other genes, over-expression of ceramidase homolog, Brain washing (bwa) in gut enteroblasts (EB) increased EB cell size and caused a non-cell-autonomous, 7-8-fold increase in ISC proliferation. Our analysis confirmed previous reports that bwa does not have ceramidase activity, and lipidomic studies indicated that bwa increases the saturation status of sphingolipids, free fatty acids, and other lipids. The pro-proliferative effects of bwa could be counter-acted by depleting a serine palmitoyltransferase, Lace, or a sphingosine acyltransferase, Schlank, which are needed for ceramide synthesis, or by co-expressing a ceramide desaturase enzyme, ifc, indicating that increased saturated ceramides were causal for ISC proliferation and the disruption of gut homeostasis. Accumulating saturated sphingolipids and fatty acids induced inflammatory signaling in the gut, and activated ISC proliferation through the pro-inflammatory cytokines, Upd3 and Upd2. We propose that saturated sphingolipids promote ISC proliferation through pro-inflammatory pathways.

cell biology↗

bioRxiv2024

Proteostasis Associated Variants in HSPB5 Destabilize the αB-crystallin Domain

HSPB5 (B-crystallin) is an ATP-independent, stress-inducible chaperone protein that improves protein misfolding and degradation in proteotoxicity-related diseases, including several myopathies, neurodegenerative diseases, and cancers. Although single nucleotide polymorphism (SNP) reduces the overall activity of HSPB5, its dynamic behaviour remains unknown. To get molecular insights into the deleterious, pathogenic, and proteotoxicity-related mutations, this study investigates the potential deleterious SNPs associated with HSPB5. Notably, eleven computational tools identified D109H, R120G, and D140N as the most deleterious SNPs from a total of 313 missense SNPs. Interestingly, these three mutations are present in the core B-crystallin (B-c) domain. A molecular dynamics simulation for 500 ns was conducted to reveal these variants mechanistic insights. The mutant variants showed higher flexibility and significant conformational changes than the wild, which might be noteworthy to reduce these variants chaperoning activity. Also, this conformational change elucidated the loss of function mutations, which could alter these variants oligomeric properties. This study will help our understanding of the role and molecular mechanism of HSPB5 mutations in proteotoxicity vulnerable diseases.

bioinformatics↗

bioRxiv2024

Natural Bacteriocins as Potential Drug Candidates Targeting Core Proteins in Mastitis Pathogens of Dairy Cattle

Mastitis poses a major challenge in the dairy industry, with rising antibiotic-resistant strains underscoring the urgent need for alternative antimicrobial strategies. This study aimed to (i) identify essential core proteins in clinical mastitis (CM)-causing pathogens using genomic approach, and (ii) assess the efficacy of natural antimicrobial peptides as novel therapeutic agents targeting the selected core proteins for the rational management of mastitis in dairy cows. Through a core genomic analysis of 16 CM-causing pathogens, including strains of Staphylococcus aureus, S. warneri, Streptococcus agalactiae, S. uberis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, P. putida, and P. asiatica, we identified 65 core proteins shared among these pathogens. Among them, ten proteins including PhoH, TrpB, FtsZ, HslV, HupB, RibH, InfA, MurA, GlxK, and Rho were found to be essential for the survival and virulence of these pathogens. Importantly, further novelty, resistance, and virulence assessments identified Rho and HupB as potential therapeutic targets. A comprehensive screening of 70 bacteriocin peptides (BPs) revealed 14 BPs that effectively interacted with both Rho and HupB proteins. Further analysis showed that BP8 and BP32 disrupt Rho protein function by blocking transcription termination process, while BP8, BP39, and BP40 prevent HupB from binding to DNA. These findings confirm the promising stability and efficacy of BP8 against both target proteins in CM-pathogens, highlighting it as a promising broad-spectrum therapeutic agent. Our computational study identified Rho and HupB as key proteins in CM-causing pathogens, which can be targeted by natural bacteriocins like BP8, suggesting its potential for developing effective and sustainable therapeutics against mastitis in dairy cattle. Author SummaryMastitis poses a significant threat to the global dairy industry, with rising antibiotic resistance necessitating alternative therapeutic strategies. This study identified essential core proteins in clinical mastitis-causing pathogens through a genomic approach and evaluated natural antimicrobial peptides (bacteriocins) as novel therapeutic agents. Through a core-genomic analysis, Rho and HupB were identified as key therapeutic targets. Bacteriocin peptides such as BP8 demonstrated promising efficacy by disrupting regular transcription termination process and DNA replication, offering a promising solution for next-generation mastitis therapies. The findings underscore the potential of BP8 as a sustainable, broad-spectrum antimicrobial agent, contributing to the rational management of mastitis in dairy cattle.

bioinformatics↗

bioRxiv2024

Streptococcus Phage Genomes Reveal Extensive Diversity, New Taxonomic Insights, and Novel Endolysin-Derived Antimicrobial Peptides

The global rise of antibiotic-resistant bacteria, particularly among Streptococcus species, poses an escalating public health threat. Traditional antibiotic development has proven inadequate, making innovative approaches such as bacteriophage-based therapies promising alternatives. A deep understanding of phage biology at the genomic level is essential for advancing therapeutic applications. Here, we analyzed 709 Streptococcus phage genomes to bridge gaps in genomic diversity and propose revisions to Streptococcus phage taxonomy. The phage genomes were clustered based on shared proteins, resulting in 66 clusters and 35 singletons with significant variation in genome characteristics. Through proteome phylogeny, average nucleotide identity, and inter-cluster core genes, we propose 21 new family-level classifications and 296 genus-level subclusters, providing an updated framework for Streptococcus phage taxonomy. Further analysis revealed diverse domain architectures in Streptococcus phage endolysins, including previously unreported structures. Specific domains were associated with distinct streptococcal hosts, suggesting adaptive evolution. We also observed variation in endolysin gene organization, with purifying selection acting on most sites, though some were subject to diversifying selection. Additionally, 182 novel endolysin-derived antimicrobial peptides (AMPs) were identified, some exhibiting antifungal, antiviral, cell-penetrating and non-toxic properties. Molecular dynamics and docking simulations demonstrated high stability and strong binding affinity of peptides EP-39 and EP-121 to the Streptococcus pneumoniae virulence factor autolysin. This is the first comprehensive comparative study of Streptococcus phage genomes, providing critical insights into phage diversity and taxonomy. It also highlights the therapeutic potential of endolysin-derived AMPs against multidrug-resistant Streptococcus strains. Further experimental validation is required to assess their clinical potential.

genomics↗

bioRxiv2024

Comparative Genome Study of Multidrug-resistant Serratia marcescens strain IU-BTGE-M-3 Isolated from a Diarrheal Patient Reveals Antibiotic Resistance Profile

Serratia marcescens is a notable pathogen known for its intrinsic and acquired antimicrobial resistance, posing challenges in healthcare. The study investigates the multidrug-resistant (MDR) Serratia marcescens strain BTGE-M-3, focusing on its genomic features and antibiotic resistance. The strain was identified using both morphological and molecular approaches, and its genome, which measured 4.97 Mbp and exhibited a GC content of 59.7%, was sequenced. The genome has 4,827 genes, including essential antibiotic resistance genes, such as tet (41) for tetracyclines, aac (6')-Ic for aminoglycosides, OqxB for fluoroquinolones, and blaSST-1 beta-lactam, alongside various virulence determinants. Comparative genomics revealed high similarity (98.06% ANI) to S. marcescens strain KS10, supporting its classification within the same species. Additionally, the genome analysis showed that S. marcescens strain IU-BTGE-M-3 comprises of 4390 gene clusters, 4564 genes, and 244 unique singleton genes. To summarize, the results showed that S. marcescens strain IU-BTGE-M-3 exhibited a high level of genomic diversity as well as diverse metabolic, cellular, and biological functions, and it is hypothesized that frequent strain exchanges resulted in the horizontal transfer of drug resistance genes. This study underscores the importance of genomic surveillance in understanding and combating antibiotic resistance in therapeutic settings.

genomics↗

bioRxiv2024

Study of Plasma Adiponectin Levels in Patients with Metabolic Syndrome and Therapeutic Indication in Bangladesh

BackgroundThe metabolic syndrome (Met-S) is a cluster of some interrelated common clinical disorders, including central obesity, dyslipidemia, hypertension, and glucose intolerance. Central obesity, accompanied by insulin resistance, is a key factor for the development of metabolic syndrome. Adiponectin is an adipose-specific plasma protein, secreted from adipocyte with anti-atherogenic and insulin-sensitizing activities. PurposeThis study aimed to investigate the relationship of plasma adiponectin levels with metabolic syndrome, related disorders and its drug repurposing through in silico approach. Materials and MethodsFor this study, 269 individuals were recruited with written consent. The participants were selected based on their full medical history, clinical examination, and laboratory reports. Anthropometric measurements as well as blood pressure was measured before sample collection. Fasting blood samples were collected for the estimation of lipid profile, blood glucose, and serum adiponectin levels. ResultsOur results show that the adiponectin levels in the subjects with Met-S were significantly lower than those of without Met-S (p <0.0001). Among the metabolic syndrome risk factors, adiponectin levels were associated with hypertriglyceridemia and reduced HDL-cholesterol (p<0.0001). Three drugs (Saquinavir, Candesartan and Glimepiride) were suggested to control the plasma adiponectin level in the subjects with Met-S. ConclusionsSince the plasma adiponectin levels are significantly lower in patients with Met-S, it might be used as diagnostic & prognostic marker for Met-S disorder and adiponectin targeted drugs might be minimize the Met-S of the subjects.

biochemistry↗

bioRxiv2024

Disorder regulates homeostasis of extracytoplasmic proteins in streptococci

Proteins harboring intrinsically disordered regions (IDRs) lacking stable secondary or tertiary structures are abundant across the three domains of life. These regions have not been systematically studied in prokaryotes. Our genome-wide analysis identifies extracytoplasmic serine/threonine-rich IDRs in several biologically important membrane-associated proteins in streptococci. We demonstrate that these IDRs are glycosylated with glucose by glycosyltransferases GtrB and PgtC2 in Streptococcus pyogenes and Streptococcus pneumoniae, and with N-acetylgalactosamine by a Pgf-dependent mechanism in Streptococcus mutans. The absence of glycosylation leads to a defect in biofilm formation under ethanol-stressed conditions in S. mutans. We link this phenotype to the C-terminal IDR of the post-translocation chaperone PrsA. Our data reveal that O-linked glycosylation protects the IDR-containing proteins from proteolytic degradation and is critical for the biological function of PrsA in biofilm formation.

microbiology↗

bioRxiv2024

A maternal high-fat diet predisposes to infant lung disease via increased neutrophil-mediated IL-6 trans-signaling

Poor maternal diet during pregnancy predisposes to severe lower respiratory tract infections (sLRI) in infancy, which in turn, increases childhood asthma risk, however the underlying mechanisms remain poorly understood. Here, we show that the offspring of high fat diet (HFD)-fed mothers ( HFD-reared pups) developed a sLRI following pneumovirus inoculation in early-life and subsequent asthma in later-life upon allergen exposure. Prior to infection, HFD-reared pups developed microbial dysbiosis and low-grade systemic inflammation (LGSI), characterized by hyper-granulopoiesis in the liver and elevated inflammatory cytokine expression, most notably IL-17A, IL-6 and sIL-6R (indicative of IL-6 trans-signaling) in the circulation and multiple organs, but most prominently the liver. Inhibition of IL-6 trans-signaling, using sgp130Fc transgenic mice or via specific genetic deletion of IL-6Ra on neutrophils, conferred protection against both diseases. Taken together, our findings suggest that a maternal HFD induces neonatal LGSI that predisposes to sLRI and subsequent asthma via neutrophil-mediated IL-6 trans-signaling.

immunology↗

bioRxiv2024

Rapid in situ mutation detection in extracellular vesicle-DNA

A PCR- and sequencing-free mutation detection assay facilitates cancer diagnosis and reduces over-reliance on specialized equipment. This benefit was highlighted during the pandemic when high demand for viral nucleic acid testing often sidelined mutation analysis. This shift led to substantial challenges for patients on targeted therapy in tracking mutations. Here, we report a 30-minute DNA mutation detection technique using Cas12a-loaded liposomes in a microplate reader, a fundamental laboratory tool. CRISPR-Cas12a complex and fluorescence-quenching (FQ) probes are introduced into tumor-derived extracellular vesicles (EV) through membrane fusion. When CRISPR-RNA hybridizes with the DNA target, activated Cas12a can trans-cleave FQ probes, resulting in fluorescence signals for the quantification of DNA mutation. Future advancements in multiplex and high-throughput mutation detection using this assay will streamline self-diagnosis and treatment monitoring at home.

bioengineering↗

bioRxiv2024

Comparative analyses of adsorbed circulating proteins in the PMMA and PES hemodiafilters in patients on predilution online hemodiafiltration

Acute and chronic inflammation are common in patients with end-stage kidney disease (ESKD). So, the adsorption of pro-inflammatory cytokines by the hollow fiber has been expected to modify the inflammatory dysregulation in ESKD patients. However, it remains to be determined in detail what molecules of fiber materials can preferably adsorb proteins from the circulating circuit. We aimed this study to analyze directly the adsorbed proteins in the polymethyl methacrylate (PMMA) and polyethersulfone (PES) membranes in patients on predilution online hemodiafiltration (OL-HDF). To compare the adsorbed proteins in the PMMA and PES hemodiafilters membrane, we initially performed predilution OL-HDF using the PES (MFX-25Seco) membrane while then switched to the PMMA (PMF-A) membrane under the same condition in three patients. We extracted proteins from the collected hemodiafilters by extraction, then SDS-PAGE of the extracted sample, protein isolation, in-gel tryptic digestion, and nano-LC MS/MS analyses. The concentrations of adsorbed proteins from the PMMA and PES membrane extracts were 35.6{+/-}7.9 {micro}g/{micro}L and 26.1{+/-}9.2 {micro}g/{micro}L. SDS-PAGE analysis revealed distinct variations of adsorbed proteins mainly in the molecular weight between 10 to 25 kDa. By tryptic gel digestion and mass spectrometric analysis, the PMMA membrane exhibited higher adsorptions of {beta}2 microglobulin, dermcidin, retinol-binding protein-4, and lambda-1 light chain than those from the PES membrane. In contrast, amyloid A-1 protein was adsorbed more potently in the PES membrane. Western blot analyses revealed that the PMMA membrane adsorbed interleukin-6 (IL-6) approximately 5 to 118 times compared to the PES membrane. These findings suggest that PMMA-based OL-HDF therapy may be useful in controlling inflammatory status in ESKD patients.

pathology↗

bioRxiv2023

Dual therapy with corticosteroid ablates the beneficial effect of DP2 antagonism in chronic experimental asthma.

BackgroundProstaglandin D2 (PGD2) signals via the DP1 and DP2 receptors. In Phase II trials, DP2 antagonism decreased airway inflammation and airway smooth muscle (ASM) area in patients with moderate-to-severe asthma, but in the Phase III clinical trials, DP2 antagonism failed to significantly lower the rate of exacerbations. Here, we hypothesised that DP2 antagonism resolves established ASM remodeling via endogenous PGD2/DP1 activation and that this beneficial effect is ablated by dual corticosteroid therapy. MethodsNeonatal mice were co-exposed to pneumonia virus of mice (PVM) and cockroach extract in early life to induce severe bronchiolitis, then re-infected with PVM and challenged to cockroach extract in adulthood to progress disease to chronic experimental asthma (CEA). The efficacy of DP2 antagonism monotherapy or various dual therapies was assessed in the setting of a rhinovirus (RV)-induced exacerbation. ResultsRV inoculation increased PGD2 release, mucus production, collagen deposition, transforming growth factor (TGF)-{beta}1 expression and type-2 inflammation. Treatment with a DP2 antagonist or DP1 agonist ablated the aforementioned phenotypes, increased type-1 immunity, and decreased ASM area. Dual DP1-DP2 antagonism or dual corticosteroid/DP2 antagonism, which attenuated endogenous PGD2 levels, prevented the resolution of ASM area induced by DP2 antagonism alone. The resolution of ASM remodelling following DP2 antagonism was mediated by IFN-{gamma} and associated with decreased TGF-{beta}1 expression. ConclusionDP2 antagonism resolved ASM remodelling via PGD2/DP1-mediated upregulation of interferon-{gamma} expression. Dual DP2 antagonism/corticosteroid therapy, as occurred in many of the human trials, suppressed PGD2 and IFN-{gamma} production, impairing the efficacy of DP2 antagonism.

immunology↗

bioRxiv2023

Three-dimensional single-cell transcriptome imaging of thick tissues

Multiplexed error-robust fluorescence in-situ hybridization (MERFISH) allows genome-scale imaging of RNAs in individual cells in intact tissues. To date, MERFISH has been applied to image thin tissue samples of [~]10-{micro}m thickness. Here, we present a thick-tissue three-dimensional (3D) MERFISH imaging method, which uses confocal microscopy for optical sectioning, deep learning for increasing imaging speed and quality, as well as sample preparation and imaging protocol optimized for image registration of thick samples. We demonstrated 3D MERFISH on mouse brain tissue sections of up to 200 {micro}m thickness with high detection efficiency and accuracy. We anticipate that 3D thick-tissue MERFISH imaging will broaden the scope of questions that can be addressed by spatial genomics.

neuroscience↗

bioRxiv2023

Knowledge, attitudes and biosecurity practices among the small-scale dairy farmers in Sylhet District, Bangladesh

BackgroundIn the context of zoonosis, Bangladeshs small-scale dairying is yet to frame satisfactory levels due to poor biosecurity practices. ObjectivesThis study intended to reveal the degree of knowledge, attitudes, and biosecurity practices among Sylhet district, Bangladeshs small-scale dairy farmers. We also focused on the association between biosecurity practices and the incidence of non-specific enteritis in humans. MethodsA questionnaire-based survey was conducted on the farmers KAP via personal interviews of 15 farmers from the randomly selected fifteen small-scale dairy farms. The questionnaire was developed with six questions for knowledge, six questions for attitude, and 12 questions for the practice of biosecurity measures. Alongside that, data on the number of non-specific enteritis cases experienced by the farmers or their family members were also recorded. Spearman correlation was used to find out the correlation among KAP variables and between practice scores and non-specific enteritis incidences. ResultsWe found an insignificant (p > 0.05) influence of demographic characteristics over knowledge, attitude, and biosecurity practices. Significant (p<0.05) and strong correlations were found in knowledge-attitude (r = 0.65), knowledge-practice (r = 0.71), and attitude-practice (r = 0.64). Incidences of non-specific enteritis and biosecurity measures practice were also strongly correlated (r = -0.9232) and statistically significant (p<0.05). ConclusionsOur study suggests that increasing knowledge and developing a good attitude are necessary to increase the adaptation of biosecurity measures as three of these factors are correlated. Also, farm biosecurity measures are closely related to human health.

scientific communication and education↗

bioRxiv2023

Genetically encoded, noise-tolerant, auxin biosensors in yeast facilitate metabolic engineering and directed evolution

Auxins are important plant growth regulating compounds that are applied in vast quantities to crops across the globe to control weeds and improve crop quality and yield. Auxins are also produced by nearly every kingdom of life and control both organismal behavior as well as inter-kingdom interactions. Improving our understanding of auxin biosynthesis and signaling is critical to both improving crop plants and controlling symbiotic, commensal, and parasitic inter-kingdom relationships, many of which are critical to ecosystems from forests and oceans to the human microbiome. We present a suite of auxin biosensors that will advance our understanding of and ability to engineer auxin perception by plants and auxin production by fungi. We have developed genetically encoded, ratiometric auxin biosensors in the model yeast Saccharomyces cerevisiae, based on the mechanism plants use to perceive auxin. The ratiometric design of these biosensors improves measurements of auxin concentration by reducing clonal and growth phase variation. These biosensors are capable of measuring exogenous auxin in yeast cultures across five orders of magnitude, likely spanning the physiologically relevant range. We implement these biosensors to measure the production of auxin during different growth conditions and phases for S. cerevisiae. Finally, we demonstrate how these biosensors could be used to improve quantitative functional studies and directed evolution of plant auxin perception machinery. These genetically encoded auxin biosensors will enable future studies of auxin biosynthesis, transport, and signaling in a wide range of yeast species, as well as other fungi, and plants. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=68 SRC="FIGDIR/small/533585v1_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@82743dorg.highwire.dtl.DTLVardef@9d5528org.highwire.dtl.DTLVardef@141cbfaorg.highwire.dtl.DTLVardef@b690e2_HPS_FORMAT_FIGEXP M_FIG C_FIG

synthetic biology↗

bioRxiv2023

Nuclear export inhibitor Selinexor targeting XPO1 enhances coronavirus replication.

Nucleocytoplasmic transport of proteins using XPO1 (exportin 1) plays a vital role in cell proliferation and survival. Many viruses also exploit this pathway to promote infection and replication. Thus, inhibiting the XPO1-mediated nuclear export pathway with selective inhibitors has a diverse effect on virus replication by regulating antiviral, proviral, and anti-inflammatory pathways. The XPO1 inhibitor, Selinexor, is an FDA-approved anticancer drug predicted to have antiviral or proviral functions against viruses. Here, we observed that pretreatment of cultured cell lines from human or mouse origin with nuclear export inhibitor Selinexor significantly enhanced protein expression and replication of Mouse Hepatitis Virus (MHV), a mouse coronavirus. Knockdown of cellular XPO1 protein expression also significantly enhanced the replication of MHV in human cells. However, for SARS-CoV-2, selinexor treatment had diverse effects on virus replication in different cell lines. These results indicate that XPO1-mediated nuclear export pathway inhibition might affect coronavirus replication depending on cell types and virus origin.

microbiology↗

bioRxiv2023

The maternal microbiome regulates infant respiratory disease susceptibility via intestinal Flt3L expression and plasmacytoid dendritic cell hematopoiesis

Severe lower respiratory infection (sLRI) are a major cause of infant morbidity and mortality, and predispose to later chronic respiratory diseases such as asthma. Poor maternal diet during pregnancy is a risk factor for sLRI in the offspring. Here we demonstrate in mice that a maternal low-fibre diet (LFD) disrupts plasmacytoid and conventional dendritic cell (DC) hematopoiesis in the offspring, predisposing to sLRI and subsequent asthma. The LFD alters the composition of the maternal milk microbiome and assembling infant gut microbiome, ablating the induction of a developmental wave of the non-redundant DC growth factor Flt3L by neonatal intestinal epithelial cells. Therapy with a propionate-producing bacteria isolated from the milk of high-fibre diet-fed mothers, or supplementation with propionate, confers protection against sLRI by restoring gut Flt3L expression and pDC hematopoiesis. Our findings identify a microbiome-dependent Flt3L axis in the gut that regulates pDC hematopoiesis in early life and confers disease resistance. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=51 SRC="FIGDIR/small/522516v1_ufig1.gif" ALT="Figure 1"> View larger version (15K): org.highwire.dtl.DTLVardef@1a39990org.highwire.dtl.DTLVardef@1b6fe67org.highwire.dtl.DTLVardef@f8440dorg.highwire.dtl.DTLVardef@13bc67e_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2022

A novel anti-cancer therapy with nuclear export inhibitor Selinexor in combination with oncolytic myxoma virus

Oncolytic viruses exploited for cancer therapy are developed to selectively infect, replicate, and kill cancer cells to stop tumor growth. However, in some cancer cells, oncolytic viruses are often limited in completing their full replication cycle, making progeny virions, and/or spread in the tumor bed due to the heterogeneous cell types within the tumor bed. Here we report that nuclear export pathway regulates oncolytic myxoma virus (MYXV) infection and cytoplasmic viral replication in a subclass of human cancer cell types where virus replication is restricted. Inhibition of CRM1/XPO-1 nuclear export pathway with nuclear export inhibitors can overcome this restriction by trapping restriction factors in the nucleus and allow significantly enhanced virus replication and killing of human cancer cells. Furthermore, knockdown of CRM1/XPO-1 significantly enhanced MYXV replication in restrictive human cancer cells and reduced the formation of anti-viral granules associated with RNA helicase DHX9. Both in vitro and in vivo, we demonstrate that the approved CRM1 inhibitor drug Selinexor enhances the replication of MYXV and cell killing of diverse human cancer cells. In the xenograft tumor model in NSG mice, combination therapy with Selinexor plus MYXV significantly reduced tumor burden and enhanced the survival of animals. Additionally, we performed global scale proteomic analysis of nuclear and cytosolic proteins in human cancer cells to identify the host and viral proteins that are upregulated or downregulated by different treatments. These results for the first time indicate that Selinexor in combination with oncolytic MYXV can be used as potential new anti-cancer therapy

microbiology↗

bioRxiv2022

Synaptotagmin-9 and Tomosyn-1 molecular complex regulates Stx1A SNAREs to inhibit insulin secretion from pancreatic beta-cells

Stimulus-coupled insulin secretion from {beta}-cells involves the fusion of insulin granules to the plasma membrane (PM) via SNARE complex formation--a cellular process key for maintaining whole-body glucose homeostasis. Optimal insulin secretion depends on how the clamping of SNAREs is released, rendering granules fusogenic. We show that an insulin granule protein synaptotagmin-9 (Syt9) deletion in lean mice increased glucose clearance, random-fed plasma insulin levels, and insulin secretion (in vivo and ex vivo islets) without affecting insulin sensitivity. These outcomes demonstrate that Syt9 has an inhibitory function in insulin secretion. Moreover, Syt9 interacts with PM-Stx1A and soluble Tomosyn-1 proteins to form non-fusogenic complexes between PM and insulin granules, preventing Stx1A-SNARE formation and insulin secretion. Furthermore, Syt9 inhibits SNARE-complex formation by posttranscriptional regulation of Tomosyn-1. We conclude that Syt9 and Tomosyn-1 are endogenous inhibitors that modulate Stx1A availability to determine {beta}-cell secretory capacity. HighlightsO_LISynaptotagmin-9 inhibits biphasic insulin secretion from {beta}-cells. C_LIO_LISynaptotagmin-9, syntaxin-1A, and Tomosyn-1 forms a molecular complex that decreases the availability of syntaxin-1A to form SNARE complexes in insulin secretion. C_LIO_LISynaptotagmin-9-mediated inhibition of insulin secretion occurs through post-transcriptional regulation of Tomosyn-1. C_LI

cell biology↗