Biology subjects

Pal, R.

Publications and source records attributed to Pal, R..

At least 19 recordsLinked to original sources

bioRxiv2026

Lateral-eyed tree shrews combine panoramic vision with an expanded oculomotor repertoire

Mammals differ in how they redirect gaze. Primates shift and hold gaze with rapid, precise eye movements that can be decoupled from the head. In lateral-eyed mammals studied to date, gaze is organized around the head: saccades are coupled to head rotation in freely moving animals and typically accompanied by attempted head movements even under head fixation. These observations suggest a trade-off: animals that keep a panoramic field give up the precise, eye-driven control of gaze typical of frontal-eyed animals. But because lateral eyes and head-centered gaze co-occur in every lateral-eyed species studied, it is unknown whether one follows from the other. Here we test this in the tree shrew, an arboreal mammal with laterally placed eyes. Using real-time eye tracking in head-fixed animals, we find that tree shrews saccade frequently under head fixation and that most saccades occur without detectable attempted head movement. Tree shrews make visually evoked saccades, along both the horizontal and vertical axes of the visual field, toward targets. They can also fixate on visual targets. Using widefield calcium imaging, we show that visual cortex over-represents the central visual field. Lastly, we show that extraocular muscles contain morphologically elaborate palisade endings, specialized nerve endings that are a constant feature of frontal-eyed species. Lateral eyes therefore do not preclude eye-driven gaze control. The two are separable dimensions of visual system design, a combination that may suit animals whose locomotion routinely points the head away from where they need to look.

neuroscience↗

bioRxiv2026

Orthogonal perturbation of sulfur availability reveals antibiotic-induced synthetic lethality in Mycobacterium tuberculosis

Despite its essential role in growth, the impact of sulfur limitation on mycobacterial physiology and antibiotic responsiveness remains poorly understood. Here, we combined chemical-genetic perturbations and infection models to investigate the consequences of sulfur limitation in Mycobacterium tuberculosis (M. tuberculosis). We report that sulfur limitation restricted bacterial growth by rewiring metabolism, resembling nutrient starvation. CRISPR interference of the sulfate transporter (ST) revealed severe vulnerability and sensitised M. tuberculosis to anti-TB drugs. Inhibition of H2S production in macrophages further compromised the fitness of ST-deficient M. tuberculosis, indicating that the bacteria depend on host-derived sulfur during infection. Importantly, preventing sulfur acquisition attenuated both the drug-sensitive H37Rv and the drug-resistant clinical strain of M. tuberculosis, while enhancing the efficacy of Isoniazid (INH) in the murine model, resulting in sterilisation of infected lung tissues. Combined, our findings suggest that restricting sulfur uptake highlights a therapeutic vulnerability that enhances the efficacy of existing anti-TB drugs.

microbiology↗

bioRxiv2026

Alternative lengthening of telomeres stratifies complex karyotype sarcomas into distinct genomic and transcriptomic states

Complex karyotype sarcomas (CKS) are heterogeneous mesenchymal malignancies that typically lack recurrent actionable oncogenic drivers and remain therapeutically challenging. Loss of ATRX is a recurrent feature of CKS and defines a particularly high-risk subgroup. ATRX loss is also associated with activation of the alternative lengthening of telomeres (ALT) pathway, and ALT-positive sarcomas have been linked to poor clinical outcomes. However, the molecular underpinnings underlying ALT-status-dependent differences in CKS, as well as the therapeutic vulnerabilities associated with ALT, remain poorly defined. By integrating C-circle-based ALT detection across 776 sarcoma samples with multi-modal sequencing of five CKS subtypes, we find that ALT activity is associated with enriched hallmarks of genomic instability. ALT-positive transcriptomes are dominated by a coordinated DNA damage response and mitotic program, in contrast to oncogenic signaling pathways that drive TERT activation in ALT-negative tumors. Long-read sequencing reveals telomere repeat clusters and telomere-mediated healing at structural breakpoints in ALT-positive tumors. These events also occur on extrachromosomal DNA (ecDNA), linking ALT activity to ecDNA biology. Together, our findings position ALT status as an important stratifying feature of CKS and identify ALT-associated transcriptional programs as potential therapeutic targets.

cancer biology↗

bioRxiv2026

Engaging working memory following skill reactivation has implications for interlimb skill generalization

Interlimb skill generalization, defined as the transfer of a newly learned skill from the trained to the untrained limb, represents a fundamental aspect of human motor behavior with significant implications for rehabilitation and athletic training. Skill generalization is influenced by processes that drive learning and interact with the newly acquired memory. For instance, in our recent work, we reported that performing a secondary, cognitively demanding task immediately after a short skill-training session impaired skill generalization when the untrained arm was tested 24-hour later. This suggests that working memory (WM) interacts with the early stage of skill memory consolidation processes and thereby impacts skill generalization. Motivated by this finding, in the current study, we investigate how WM interacts with reactivated skill memory and its subsequent impact on skill generalization, tested 24 or 48-hour post skill training. We recruited right-handed young participants (n=95) who performed a fast, accurate reaching task with their dominant right arm during a short training session (50 trials) on Day-1. After 24-hour on Day-2, depending on the group type, participants had a brief skill reactivation session (10 trials or no reactivation) and then performed the WM task (or a control task) with their right arm. Interlimb generalization to the untrained left arm was assessed either immediately after the WM/control task on Day-2 or after a 24-hour gap on Day-3. We found that, engaging in the WM task (compared to the control task) after skill reactivation on Day-2 enhanced immediate generalization. Conversely, when generalization was tested 24-hour later on Day-3, the same WM engagement impaired skill generalization. These findings demonstrate that WM engagement during the post-reactivation phase has a time-dependent influence on interlimb generalization. WM can facilitate immediate generalization, possibly by sustaining neural processes that promote skill memory generalization across effectors. However, when a 24-hours time gap is introduced, generalization is disrupted following WM engagement, possibly because of interference between underlying neural processes involved in WM and reactivation-induced (re)consolidation of the skill memory. This study highlights the delicate interplay among WM, motor memory reactivation dynamics, and skill generalization and suggests a time-dependent interplay of neural processes critical for optimizing outcomes in motor learning and clinical rehabilitation protocols. NEW & NOTEWORTHYThis study reveals that working memory engagement following skill memory reactivation exerts a time-dependent dual effect on interlimb generalization. When tested immediately, WM engagement enhances generalization by prolonging the labile state of reactivated memory, which is needed to transfer abstract/effector-independent features to the untrained arm. When tested 24-hour after a delay, the same intervention impairs generalization by possibly engaging reconsolidation processes that interfere with effector-independent features. These findings establish a unified framework in which the temporal dynamics of the reconsolidation window determine whether a cognitive intervention strengthens or weakens a motor memory, with implications for understanding memory plasticity and for designing effective rehabilitation protocols.

neuroscience↗

bioRxiv2026

Epistatic interaction between ribosome-associated Era GTPase and stringent response regulator RelA modulates bacterial cell growth and dormancy

Cellular homeostasis is sustained by balancing the cell growth and quiescence in response to specific environmental cues. While the mechanisms governing the transition from growth to dormancy are reasonably well understood, the processes underlying exit from dormancy remain poorly characterised. Using an integrated approach employing bacterial genetics, Cryo-EM, and molecular microbiology, we investigated this phenomenon by studying the cross-talk between two antagonistic pathways, ribosome biogenesis that promotes cell growth, and stringent response that induces dormancy. We show that the exit from dormancy requires a conserved Era GTPase whose synthesis selectively rises during onset of exponential growth phase in Escherichia coli. Era not only accelerates the maturation of head and platform regions of 30S ribosomal subunit but also dislodges RelA from 70S ribosome. This derepresses the 70S ribosome from RelA-mediated inhibition, and promotes protein synthesis driving the active cell growth. This study uncovers that temporal epistatic interaction between Era and RelA governs cellular resuscitation in bacteria. Given that the dormant bacterial populations contribute to antibiotic tolerance, understanding this regulatory axis offers new insights for resensitising the recalcitrant dormant bacteria to antibiotics.

microbiology↗

bioRxiv2025

Metabolic regulation of copper homeostasis governs the Sec61-dependent protein translocation process in Saccharomyces cerevisiae

Concentration of cellular labile pool of copper must be strictly regulated because disruption in copper homeostasis results in diseases. In Saccharomyces cerevisiae, elevated levels of labile copper impair cell viability by inhibiting Sec61-mediated protein translocation into the endoplasmic reticulum. We investigated how metabolic pathways, specifically mitochondrial respiration and autophagy, contribute to copper homeostasis and the translocation of secretory proteins. We show that copper selectively inhibits protein translocation in yeast cells grown in minimal medium but not in rich medium, highlighting a critical role of nutrients in modulating copper toxicity. Supplementation of specific amino acids suppresses the copper-induced defects in protein translocation and cell death, identifying amino acids suppressors of the copper toxicity. Using a panel of gene deletion mutants affecting mitochondrial functions, autophagy, peroxisomes, and lipid droplets, we demonstrate that metabolic pathways regulate sub-cellular distribution of copper and translocation of secretory proteins. Further, disruption of redox and pH homeostasis, and pharmacological inhibition of respiration, reveals that correct subcellular trafficking of copper is essential to prevent inhibitory effects on protein translocation process. Together, our findings provide mechanistic insights into how metabolic status influences cellular copper homeostasis and the secretory pathway of proteins, with broader implications for understanding diseases of copper metabolism.

cell biology↗

bioRxiv2025

AdapToR: Adaptive Topological Regression for quantitative structure-activity relationship modeling

Quantitative structure-activity relationship (QSAR) modeling has become a critical tool in drug design. Recently proposed Topological Regression (TR), a computationally efficient and highly interpretable QSAR model that maps distances in the chemical domain to distances in the activity domain, has shown predictive performance comparable to state-of-the-art deep learning-based models. However, TRs dependence on simple random sampling-based anchor selection and utilization of radial basis function for response reconstruction constrain its interpretability and predictive capacity. To address these limitations, we propose Adaptive Topological Regression (AdapToR) with adaptive anchor selection and optimization-based reconstruction. We evaluated AdapToR on the NCI60 GI50 dataset, which consists of over 50,000 drug responses across 60 human cancer cell lines, and compared its performance to Transformer CNN, Graph Transformer, TR, and other baseline models. The results demonstrate that AdapToR outperforms competing QSAR models for drug response prediction with significantly lower computational cost and greater interpretability as compared to deep learning-based models.

bioinformatics↗

bioRxiv2025

Turning blood to brain cells: a plasma mediated reprograming model

The lack of effective stem cell protocols for generating personalized neurovascular niches poses a critical challenge in precision medicine. While iPSC-based methods are explored, their clinical use is hindered by high costs, long timelines, and cancer risks. Recent advancements in plasma-driven differentiation, using circulating monocytes, offer a promising solution as they can be reprogrammed into neuron-like, endothelial-like, and hematopoietic cells without genetic manipulation, by inducing growth factors mediated transdifferentiation. Vasculature is integral to neurodevelopment, with early blood supply transitioning from the perineural to intrinsic vascular plexus, driven by neuro-hematovascular signaling. The choroid plexus selectively transports proteins and growth factors from blood to CSF, supporting neural proliferation and differentiation. Building on these insights, we leveraged the innate reprograming potential of blood-derived cells to generate neuro-hematovascular niches using a novel PITTRep methodology, devoid of transgene and growth factor mediated transdifferentiation opening new avenues for regenerative and investigative neurovascular studies.

cell biology↗

bioRxiv2025

Dynamical interactions among compositionally distinct protocell populations and its implications for evolution of early membranes

The spontaneous self-assembly of single chain amphiphiles (SCAs) would have resulted in multiple protocell species in an early-Earth niche. Considering the heterogeneity inherent in a prebiotic milieu, interactions between physicochemically distinct protocell populations was evaluated to discern if emergent properties occurred at a systems level. This study demonstrates that depending on the physicochemical properties of the membrane, interacting populations are endowed with varied emergent properties owing to their coexistence. In a multispecies paradigm involving a two-candidate protocell system, the fitter population acted as a predator and grew at the expense of the less-fit prey population. The observed growth could be attributed to the predator attaining a more robust membrane via chemical evolution. Importantly, the prey population also accrued emergent properties like molecular crowding, and coexist in balance with the predator population, without being completely outcompeted. When extrapolating these results to a three-candidate population, the outcomes were multipronged. These findings suggest a possible route for protocell membrane evolution that could have occurred even in the absence of any sophisticated protein machinery, benefitting coexisting populations, while also illustrating evolutionary trajectories that potentially resulted in functionally complex protocells.

biophysics↗

bioRxiv2025

Exploring vitamin D and its analogues as a possible therapeutic intervention in targeting inflammatory mediators in neurodegenerative disorders like Parkinsons disease

Parkinsons disease characterized by dopaminergic neuronal death has been linked with neuroinflammatory processes which involve self-perpetuating detrimental events leading to prolonged neurodegeneration. Vitamin D has been found to possess neuroprotective and immuno-modulatory effects which might justify elevated inflammation and hypovitaminosis D in PD patients. So, we aimed to find the possible interactions of Vitamin-D and its analogues with inflammatory mediators prevalent in PD to get more insight into Vitamin-Ds role in neuroinflammation by assessing specific interactions between Vitamin-D and its marketed analogues with different inflammatory mediators. Moreover, revealing a possible drug repurposing with Vitamin-D analogues against neuroinflammation and other inflammatory conditions. Molecular docking was conducted with 10 inflammatory markers (p38 MAPK, NF-{kappa}B, iNOS, nNOS, COX-2, TNF, IL6, TNF, IL1{beta}, CRP) with bio-active form of Vitamin-D (calcitriol) and its analogues. Among the studied ligands, calcitriol, calcipotriol, seocalcitol, paricalcitol and falecalcitriol were found to be potential inhibitors of different inflammatory agents. Specific standard drugs or experimental inhibitors were used to compared the binding affinity between protein and ligand. BBB permeability of the tested ligands also checked as well as neurotoxicity. Most of the ligands were found to be BBB permeable possibly interacting with inflammatory mediators within the brain and were also found to be non-neurotoxic. This study sheds light on VD and its analogues being possible candidates against various inflammatory markers. The findings could further be used as stepping stone for new study on repurposing of these analogues in neuroinflammation and other inflammatory disease conditions.

bioinformatics↗

bioRxiv2024

Building neurovascular tissue from autologous blood for modeling brain-activity

There are no faithful individualized stem cell-based bioengineered neuro-vascularized models that can recapitulate the physiological hemodynamic phenomenon of neuro-vascular coupling (NVC)-the principal behind BOLD (blood oxygen level-dependent) signal in functional neuroimaging, thereby dissuading the research in exploring the brain activity-based investigative studies in neurological/neurosensory diseases. This encouraged us to establish a preclinical optoacoustic (Hb/dHb hemoglobin/deoxyhemoglobin) imaging-competent in vitro neuro-vascularized model by employing a novel cellular reprograming PITTRep (Plasma Induced Transcriptomics/ epi-Transcriptomics Reprograming) approach. The current reprograming approach is based on coaxing autologous blood components to ecto-mesodermal lineage intermediates that can subsequently self-pattern into neurovascular tissue by harnessing the hemorheological properties of RBCs. The nature of blood flow is non-Newtonian and is a function of RBC concentration /haematocrit when they flow through the regions of low shear rates as seen in cerebral microcirculation. The current reprograming approach is a modification of our previous cellular reprograming approach that employed a Newtonian plasma fluid. The autologous blood-derived neurovascular tissue is free from exogenous genetic modification, external growth factors, and induced pluripotent stem cell (iPSC) derivation. This model uniquely integrates functional vasculature and neurogenesis. The current reprogramming approach resulted (in part) serendipitously while testing a potential (yet completely unexplored) hypothesis of haemodynamic reprograming by leveraging the fluid mechanic feature of blood erythrocytes as seen in thrombus formation during cerebral ischemic stroke, that is characterized by physiologically intriguing yet clinically meaningful neurological recovery (neuroplasticity) during an early time window. The current study attempted to induce "a post stroke-like model" of adult neurogenesis with functional synaptogenesis by instructing autologous blood components into thrombus formation through incorporation of erythrocytes in varying concentrations. We tried to instruct adult neurogenesis and neuroplasticity (a relatively non-resilient phenomenon under in vitro conditions) by co-induction of a neuro-vascular niche (NVN). These NVNs are marked by dendrites, synapses, astrogliosis, microglia activation, and growth factor signaling, thus phenocopying molecular and cellular aspects of post-stroke recovery window. The induction of neuro-vascularized niches and functional neuro-vascular coupling (NVC) was characterized by confocal microscopy, scanning electron microscopy, proteomic profiling, and Hb/dHb spectra based optoacoustic imaging. The blood thrombus formation was checked by rotational thromboelastometry (ROTEM), and switching of adult-to-embryonic hemoglobin was confirmed by routine hemoglobin typing. We also attempted to establish patient-specific neuro-vascularized niches from autologous blood of sensorineural hearing loss (SNHL) patients. The individualized neovascularised tissues are intended to be employed for investigating deregulated synaptic plasticity/ long term potentiation underlying poor auditory comprehension outcomes in school going kids suffering from SNHL that greatly compromises their academic performance and socio-behavioural-cognitive development. The attendant multiomics of patient-specific NVNs may have potential implications in developing stem-cell based therapies for neurosensory and cerebrovascular diseases.

neuroscience↗

bioRxiv2024

The Fragile X Messenger Ribonucleoprotein 1 regulates the morphology and maturation of human and rat oligodendrocytes

The Fragile X Messenger Ribonucleoprotein (FMRP) is an RNA binding protein that regulates the translation of multiple mRNAs and is expressed by neurons and glia in the mammalian brain. Loss of FMRP leads to Fragile X Syndrome (FXS), a common inherited form of intellectual disability and autism. While most research has been focusing on the neuronal contribution to FXS pathophysiology, the role of glia, particularly oligodendro-cytes, is largely unknown. FXS individuals are characterised by white matter changes which imply impairments in oligodendrocyte differentiation and myelination. We hypothesized that FMRP regulates oligodendrocyte maturation and myelination during postnatal development. Using a combination of human pluripotent stem cell - derived oligodendrocytes and an Fmr1 knockout rat model, we studied the role of FMRP on mammalian oligodendrocyte development. We found that the loss of FMRP leads to shared defects in oligodendrocyte morphology in both rat and human systems in vitro which persist in the presence of FMRP expressing axons in chimeric engraftment models. Our findings point to species-conserved, cell-autonomous defects during oligodendrocyte maturation in FXS.

neuroscience↗

bioRxiv2024

ROLE OF WORKING MEMORY IN INTERLIMB GENERALIZATION OF NEWLY LEARNED SKILLS

Newly acquired skill memory can generalize/transfer to the untrained arm. Such interlimb generalization of a learned skill has been shown to be symmetric in nature and is thought to be mediated by cognitive processes that emerge during skill learning. However, it is unknown whether engaging in other cognitively demanding tasks following skill acquisition can influence skill generalization. Our research goal was to uncover how a secondary task, involving working memory, interacts with a newly formed skill memory and influences subsequent interlimb generalization. To test this idea, we conducted a set of three experiments by recruiting right-handed young healthy individuals (N=92) who learned a novel motor skill (long or short training on a skilled reaching task) followed by performing a working memory or control task with the right arm. Finally, all individuals were tested for immediate or delayed (after 24 hours) interlimb skill generalization to the untrained left arm. We found significant immediate as well as delayed generalization in individuals who received long training on the motor skill task, irrespective of whether they performed working memory or control task. On the other hand, performing the working memory but not control task following short skill training impaired generalization when the untrained arm was tested 24 hours later. These findings indicate that short training reflecting early stages of skill learning and the subsequent skill memory stabilization are dependent on working memory such that the underlying neural interactions mediating these processes can have implications for skill generalization. NEW AND NOTEWORTHYSkill learning is deemed successful if it can generalize to untrained conditions. Despite the potential clinical relevance of interlimb skill generalization for motor rehabilitation, such as in case of unilateral stroke, the underlying mechanisms that can influence such generalization are not fully understood. Specifically, whether interlimb skill memory generalization can be impacted by another memory system is unknown. Here, we show that engaging in a working memory task following short skill training is detrimental for interlimb skill generalization, and such interference caused by working memory is not evident when the skill training is longer. These behavioral findings bridge the link between traditionally distinct memory systems, i.e., procedural skill memory and working memory.

neuroscience↗

bioRxiv2024

pH dependent direct sulfhydrylation pathway is required for pathogenesis of Mycobacterium tuberculosis

Methionine is essential for the survival of Mycobacterium tuberculosis (M. tuberculosis) inside the host. However, the transsulfuration pathway, a major contributor of methionine, is dispensable for the growth of M. tuberculosis suggesting redundancy in the methionine biosynthesis pathway. Orthologues of MetZTB in other bacterial species are known to operate a redundant single-step methionine biosynthesis pathway called direct sulfhydrylation. In this study, we demonstrate that genetic disruption of the metZ-mediated direct sulfhydrylation pathway in M. tuberculosis hinders growth at low pH, an effect mitigated by methionine supplementation. Computational analyses, including in-silico molecular docking and molecular dynamics (MD) simulations, reveal enhanced binding of the MetZ substrate, O-succinyl homoserine (OSH), to the active site of MetZ at acidic pH. Intriguingly, despite increased intracellular ATP levels, a relative decrease in the frequency of Bedaquiline (BDQ)-induced persisters is observed in metZ-deficient strain, suggesting a role of direct sulfhydrylation pathway in modulating BDQ sensitivity. Finally, we demonstrated that the absence of metZ impedes the ability of M. tuberculosis to grow inside the host.

microbiology↗

bioRxiv2024

Phosphoglucomutase A mediated regulation of carbon flux is essential for antibiotic and disease persistence in Mycobacterium tuberculosis

The long-term survival of Mtb mandates judicious utilization of the available resources inside the host. Uninterrupted access to host-derived nutrients holds the key to the success of Mtb. Phosphoglucomutase enzyme besides synthesizing glycogen, which serves as a nutrient reservoir, also helps modulate the carbon flux in different pathogens. Studies on the role of glycogen metabolism in disease progression, reactivation, and drug susceptibility in tuberculosis are severely lacking. To investigate this, we generated an Mtb strain ({Delta}pgmA) devoid of the gene that encodes for the enzyme phosphoglucomutase A (pgmA). The absence of pgmA impedes the ability of the pathogen to survive under nutrient-limiting and reactivation conditions. In the current study, we demonstrate that the absence of cell membrane-associated glycolipids in {Delta}pgmA compromised the cell wall integrity and increased the susceptibility of {Delta}pgmA to various stresses. Interestingly, in comparison to the wild type, low cAMP levels in {Delta}pgmA imparted an enhanced growth phenotype on cholesterol. Differential gene expression and carbon flux analysis suggest that stored carbon in the form of glycogen is essential for the survival of Mtb under nutrient-limiting conditions. Finally, we demonstrate that the pgmA gene of Mtb is essential for the growth of Mtb inside the host. Overall, this study unveils the significance of pgmA-mediated regulation of membrane glycolipids and its implication on antibiotic and disease persistence in tuberculosis. Additionally, information derived from this study will help design anti-TB strategies that are novel, short, and more efficient.

microbiology↗

bioRxiv2024

Resolving the three-dimensional interactome of Human Accelerated Regions during human and chimpanzee neurodevelopment

Human Accelerated Regions (HARs) are highly conserved across species but exhibit a significant excess of human-specific sequence changes, suggesting they may have gained novel functions in human evolution. HARs include transcriptional enhancers with human-specific activity and have been implicated in the evolution of the human brain. However, our understanding of how HARs contributed to uniquely human features of the brain is hindered by a lack of insight into the genes and pathways that HARs regulate. It is unclear whether HARs acted by altering the expression of gene targets conserved between HARs and their chimpanzee orthologs or by gaining new gene targets in human, a mechanism termed enhancer hijacking. We generated a high-resolution map of chromatin interactions for 1,590 HARs and their orthologs in human and chimpanzee neural stem cells (NSCs) to comprehensively identify gene targets in both species. HARs and their chimpanzee orthologs targeted a conserved set of 2,963 genes enriched for neurodevelopmental processes including neurogenesis and synaptic transmission. Changes in HAR enhancer activity were correlated with changes in conserved gene target expression. Conserved targets were enriched among genes differentially expressed between human and chimpanzee NSCs or between human and non-human primate developing and adult brain. Species-specific HAR gene targets did not converge on known biological functions and were not significantly enriched among differentially expressed genes, suggesting that HARs did not alter gene expression via enhancer hijacking. HAR gene targets, including differentially expressed targets, also showed cell type-specific expression patterns in the developing human brain, including outer radial glia, which are hypothesized to contribute to human cortical expansion. Our findings support that HARs influenced human brain evolution by altering the expression of conserved gene targets and provide the means to functionally link HARs with novel human brain features.

genomics↗

bioRxiv2024

The effect of a dominant kinase-dead Csf1r mutation associated with adult-onset leukoencephalopathy on brain development and neuropathology.

Amino acid substitutions in the kinase domain of the human CSF1R protein are associated with autosomal dominant adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP). To model the human disease, we created a disease-associated mutation (Glu631Lys; E631K) in the mouse Csf1r locus. Previous analysis demonstrated that heterozygous mutation (Csf1rE631K/+) had a dominant inhibitory effect on CSF1R signaling in vitro and in vivo but did not recapitulate the pathology of the human disease. We speculated that leukoencephalopathy in humans requires an environmental trigger and/or epistatic interaction with common neurodegenerative disease-associated alleles. Here we examine the impact of heterozygous Csf1r mutation on microglial phenotype, normal postnatal brain development, age-related changes in gene expression and on two distinct pathologies in which microgliosis is a prominent feature, prion disease and experimental autoimmune encephalitis (EAE). The heterozygous Csf1rE631K/+ mutation reduced microglial abundance and the expression of microglial-associated transcripts relative to wild-type controls at 12 weeks and 43 weeks of age but had no selective effect on homeostatic markers such as P2ry12. An epistatic interaction was demonstrated between Csf1rE631K/+ and Cxc3r1EGFP/+ genotypes leading to dysregulated microglial and neuronal gene expression in both hippocampus and striatum. Heterozygous Csf1rE631K mutation reduced the microgliosis associated with both diseases. There was no significant impact on disease severity or progression in prion disease. In EAE, induced expression of inflammation-associated transcripts in the hippocampus and striatum was suppressed in parallel with microglia-specific transcripts, but spinal cord demyelination was exacerbated. The results support a dominant-negative model of CSF1R-associated leukoencephalopathy and likely contributions of an environmental trigger and/or genetic background to neuropathology.

neuroscience↗

bioRxiv2023

Hypothetical gene Rv0495c regulates redox homeostasis in Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) has evolved sophisticated surveillance mechanisms to regulate and neutralize redox imbalances and associated lethal consequences. Failing this, the accumulated ROS induces toxicity by oxidizing a variety of biological molecules including proteins, nucleic acids and lipids. In the present study we identified Mtbs Rv0495c gene as an important regulator of oxidized cytosolic environment. Compared to wild type Mtb strain lacking the Rv0495c gene, {Delta}Rv0495c, had increased ROS and NAD+/NADH ratio creating a highly oxidized intracellular environment. {Delta}Rv0495c strain demonstrated slow growth phenotype under in vitro and ex-vivo growth conditions and demonstrated enhanced susceptibility to drugs, oxidative, nitrosative and hypoxic growth conditions. In addition, the increase in the superoxide radicals triggered a Fenton-like reaction rendering the {Delta}Rv0495c susceptible to free iron. The increase in the intracellular ROS levels of the {Delta}Rv0495c was further corroborated by an increase in the expression of proteins involved in antioxidant defense and enhanced ROS-mediated oxidation and degradation of mycobacterial lipids. This superoxide-induced lipid degradation resulted in altered colony morphology and loss of membrane integrity in the {Delta}Rv0495c. Surprisingly, despite showing a growth defect phenotype in an ex-vivo macrophage infection model, the absence of the Rv0495c gene in Mtb enhanced the pathogenicity and augmented the ability of the Mtb to grow inside the host. Gene expression analysis revealed a Rv0495c mediated immunomodulation of the host controls inflammation and helps creates a favorable niche for long-term survival of Mtb inside the host. In summary, the current study underscores the fact that the truce in the war between the host and the pathogen favors long-term disease persistence in tuberculosis. We believe targeting Rv0495c could potentially be explored as a strategy to potentiate the current anti-TB regimen.

microbiology↗