Biology subjects

Kumaran, M.

Publications and source records attributed to Kumaran, M..

11 recordsLinked to original sources

bioRxiv2026

KiMA: Kinematic Motion Analysis for Spinal Cord Injury Research

Accurate quantification of locomotor recovery is essential for evaluating therapeutic outcomes in spinal cord injury (SCI) models. Manual scoring systems remain observer-dependent, and commercial gait-analysis platforms are costly and proprietary. Markerless pose-estimation tools such as DeepLabCut generate accurate body-part coordinates, but converting these coordinates into biologically meaningful locomotor parameters typically requires custom programming and multiple external tools. We developed KiMA (Kinematic Motion Analysis), an open-source, browser-based suite for integrated analysis of rodent gait and hindlimb kinematics. KiMA accepts DeepLabCut coordinate files and performs automated coordinate parsing, stick-figure reconstruction, frame-by-frame movement inspection, and single- and multi-sample analysis, with dedicated workflows for ladder and rung analysis, footfall detection, and CatWalk gait analysis. The platform quantifies joint angles (metatarsophalangeal, ankle, knee, hip, and pelvic), stride length, stride width, cadence, stance and swing durations, paw-contact events, swing clearance, and locomotor symmetry, and supports cohort-level comparisons, correlation analysis, principal component analysis, and export of processed datasets and publication-quality figures. Because KiMA runs entirely within a standard web browser, it requires no software installation or local programming environment, supporting cross-platform accessibility and data privacy. By unifying gait quantification, visualization, and multivariate analysis in a single interface, KiMA lowers the computational barrier to markerless locomotor analysis and helps researchers detect subtle functional recovery after SCI.

bioinformatics↗

bioRxiv2026

Combinatorial Control of Corticospinal Axon Growth by Retinoic Acid Receptors

Regeneration of central nervous system (CNS) axons depends on Transcription Factors (TFs) that reactivate developmental growth programs, yet most such factors remain unknown. By intersecting developmental chromatin binding with pro-growth gene networks, we identified two retinoic acid receptor transcription factors, RARA and RARG, whose occupancy at growth-associated genes is progressively lost as neurons mature. Restoring both factors together increased neurite outgrowth beyond either alone in two independent systems, the Neuro-2a cell line and primary cortical neurons. In vivo, the same combination drove cross-midline sprouting after pyramidotomy and long-tract regeneration after thoracic spinal cord crush, with concordant recovery of hindlimb gait and grip strength. Interestingly, neither receptor alone was sufficient, hinting at combinatorial regulation. Single-nucleus transcriptomics delineated that only the combination reactivated relevant cytoskeletal and gene-expression programs, while genome-wide binding maps showed that RARA and RARG partition the regulatory landscape, with RARG dominating promoters and RARA occupying distal enhancers, so that neither receptor reconstitutes the developmental growth state alone. Intriguingly, this cooperative requirement was specific to the CNS: in peripheral sensory neurons, RARG alone was sufficient and RARA was dispensable. These data identify RARA and RARG as novel cooperative regulators of regenerative axon growth in mammalian CNS and PNS neurons and potential targets for therapeutic intervention.

neuroscience↗

bioRxiv2026

Rewiring of the three-dimensional genome encodes regenerative potential in the adult central nervous system

The failure of adult central nervous system neurons to regenerate after injury has been attributed to transcriptional and epigenetic barriers, but whether three-dimensional genome organization constitutes an independent regulatory layer encoding regenerative potential remains unknown. Here we present the first genome-wide map of chromatin compartments, topologically associating domains, and loops across postnatal development, adult homeostasis, and spinal cord injury in the mouse motor cortex. Postnatal maturation progressively consolidates a growth-restrictive three-dimensional architecture, and spinal cord injury alone partially reverses this consolidation, re-engaging neonatal gene programs through reorganized but functionally recapitulative architecture despite minimal transcriptional activation. This reversion is directed rather than stochastic, preferentially targeting pro-growth gene networks, and reveals a latent three-dimensional memory of developmental growth states in the adult cortical genome. Strikingly, NR2F6, a transcription factor that promotes corticospinal axon regeneration, extends this reversion beyond the neonatal state toward an earlier embryonic chromatin configuration, a depth of developmental plasticity that injury alone cannot reach. These findings establish three-dimensional genome topology as a regulatory layer encoding regenerative potential in adult cortical neurons, demonstrating that successful CNS regeneration requires accessing embryonic rather than merely neonatal chromatin states, and reframing regenerative failure as a topological problem with new therapeutic targets.

neuroscience↗

bioRxiv2025

PATZ1 remodels the nucleosome landscape to promote chromatin accessibility in injured neurons

Adult central nervous system neurons fail to regenerate after injury, in part due to epigenetic constraints that maintain a growth-restrictive chromatin state. We previously showed that the transcription factor PATZ1 reprograms chromatin accessibility in injured corticospinal neurons to promote axon regeneration, but the underlying mechanism remained unclear. Here we use nucleosome-resolution profiling to reveal that PATZ1 induces widespread nucleosome eviction at regeneration-associated gene loci. PATZ1 treatment dramatically reduces both nucleosome occupancy and fuzziness, indicating active chromatin remodeling rather than passive destabilization. This remodeling occurs preferentially at distal regulatory elements, where PATZ1 drives a greater than 3-fold expansion of H3K27ac-marked active enhancers. Nucleosome eviction at these sites precedes enhancer activation, establishing a mechanistic link between chromatin remodeling and transcriptional reprogramming. Our findings demonstrate that targeted nucleosome eviction at enhancers underlies PATZ1-mediated chromatin reorganization, providing mechanistic insight into how epigenetic barriers to CNS regeneration can be overcome.

neuroscience↗

bioRxiv2025

Targeting RARβ With a Stable Retinoic Acid Mimic Promotes Neurite Outgrowth, Neurogenesis, and Behavioral Recovery

Injury to the adult central nervous system triggers minimal axonal regeneration, partly due to the limited activation of intrinsic growth programs. Retinoic acid (RA) signaling has been shown to promote modest regenerative responses, but its clinical utility is restricted by poor biochemical stability and short-lived receptor engagement. Here, we report a tribenzamide-based small molecule DM04, that recapitulates RA-like transcriptional and phenotypic effects and enhances regenerative outcomes, independent of canonical RARE-dependent transactivation. DM04 promoted neurite outgrowth in primary neurons, upregulated canonical RA-responsive genes, and supported neural induction from human iPSCs. In a murine spinal injury model, DM04 treatment improved motor recovery. Transcriptomic analysis revealed shared target gene activation between RA and DM04, along with unique enrichment of extracellular matrix remodeling pathways. These findings establish DM04 as a small molecule based approach with dual efficacy in injury and developmental contexts, acting through a mechanism distinct from canonical RAR transactivation, and highlight its promise as a candidate for further preclinical investigation in neural repair.

neuroscience↗

bioRxiv2025

Deep Neurite Analysis Tool (DeNAT): A machine-learning framework for precise automated neurite outgrowth measurement

Accurate quantification of neurite sprouting after injury is a critical step in axon regeneration research. Yet it remains a major bottleneck, as the current gold standard relies on manual counting by multiple blinded observers. This process is slow, labor-intensive, and prone to variability. While some software can measure total neurite length, they arent made to specifically measure new growth in complicated images from real-life injury models, like the thoracic crush and pyramidotomy model. Existing software can measure total neurite length in culture, but it is not designed to capture new growth in complex images from injury models, such as thoracic crush or pyramidotomy. Crucially, these tools lack the ability to selectively analyze growth within user-defined regions, a key requirement for injury paradigms. To address this need, we developed the Deep Neurite Analysis Tool (DeNAT), an accessible deep-learning-based platform that automatically measures neurite outgrowth after injury. DeNAT allows users to define regions of interest to specifically quantify sprouting in images from common spinal cord injury paradigms. We benchmarked its performance against manual scoring and conventional automated approaches. DeNAT achieved 87 percent accuracy in detecting neurite sprouts relative to manual counts, while reducing variability and labor. By combining user-guided region selection with automated deep learning analysis, DeNAT offers an accurate, reproducible, and efficient solution for measuring neurite outgrowth in injury models.

bioinformatics↗

bioRxiv2025

Nuclear Receptor Transcription factors promote axon regeneration in the Adult Corticospinal Tract

Transcription factors are potent levers for neural repair, but which factors govern regenerative capacity in the corticospinal tract remains largely unknown. By intersecting developmental RNA-seq with ATAC-seq footprinting, we identified two nuclear-receptor transcription factors, NR2F1 and NR2F6, neither previously linked to CNS axon growth, whose chromatin occupancy at pro-growth enhancers is progressively lost as neurons mature. Forced expression of either factor significantly increased neurite outgrowth in single-neuron tracing assays, and each drove strong cross-midline sprouting after pyramidotomy and long-tract CST regeneration after complete thoracic crush, with concordant recovery of hip-rise kinematics and grip strength. Parallel multi-omic profiling (CUT&RUN, snRNA-seq and Ribo-seq) of both factors together with NR2F6 Hi-C revealed distinct mechanisms: NR2F1 reactivated chromatin-remodeling and cytoskeletal programs, whereas NR2F6, via a conserved corepressor domain, re-occupied developmental enhancers, reorganized three-dimensional chromatin architecture into new topologically associating domains, and imposed a transient translational down-shift in which growth-relevant modules were selectively preserved through translational buffering. Together, these data identify NR2F nuclear receptors as regulators of corticospinal regeneration, acting through enhancer redeployment, translational reprogramming and three-dimensional genome reorganization.

neuroscience↗

bioRxiv2025

PATZ1 Reinstates a Growth-Permissive Chromatin Landscape in Adult Corticospinal Neurons After Injury

BackgroundThe failure of axon regeneration in the adult central nervous system represents a major barrier to recovery from spinal cord injury and neurodegenerative disease. Pro-growth transcription factors can promote regenerative responses, but their effects remain partial, suggesting that additional restraints must be relieved for these factors to achieve their full potential. The chromatin landscape of adult neurons has emerged as a candidate mechanism, yet we lack a developmental map of when and how this epigenetic restriction occurs, whether injury can reverse it, and how to therapeutically target it. ResultsWe assembled a comprehensive chromatin accessibility atlas spanning mouse forebrain development from embryonic day 11 through adulthood using bulk and single-nucleus ATAC-seq. This revealed progressive restriction of growth-gene promoters and enhancers across postnatal development, leaving over 95% of growth-associated regulatory elements substantially inaccessible in mature neurons. We found that the distance between injury site and neuronal cell body determines the magnitude of chromatin reopening: intracortical lesions proximal to motor cortex soma triggered ten-fold greater enhancer reactivation compared to distal thoracic spinal cord crush. Motif analysis identified PATZ1, a chromatin-remodeling transcription factor, as correlated with this proximity effect. Viral delivery of PATZ1 to adult cortex converted the limited epigenomic response to distal injury into a profile approaching that of proximal injury, selectively reopening enhancers at growth-associated loci and depositing active H3K27ac marks. Hi-C analysis demonstrated that PATZ1 additionally reorganizes higher-order chromatin architecture, inducing compartment switching at growth loci and remodeling topologically associating domain boundaries. Integration with single-nucleus transcriptomics revealed that while PATZ1 selectively opens chromatin at growth genes, transcriptional output and axon regeneration remain modest, indicating that combinatorial approaches pairing epigenetic priming with pro-growth transcription factors may be required for functional repair. ConclusionsThis study provides a developmental timeline of chromatin closure at regeneration-associated genes and identifies PATZ1 as a molecular tool capable of reversing this epigenetic barrier in adult neurons. Our findings indicate that chromatin accessibility functions as a gatekeeping mechanism that must be addressed before transcription factor-based therapies can achieve their full effect, establishing epigenetic priming as a targetable component of CNS repair strategies.

neuroscience↗

bioRxiv2024

Injury distance limits the transcriptional response to spinal injury

The ability of neurons to sense and respond to damage is fundamental to homeostasis and nervous system repair. For some cell types, notably dorsal root ganglia (DRG) and retinal ganglion cells (RGCs), extensive profiling has revealed a large transcriptional response to axon injury that determines survival and regenerative outcomes. In contrast, the injury response of most supraspinal cell types, whose limited regeneration constrains recovery from spinal injury, is mostly unknown. Here we employed single-nuclei sequencing in mice to profile the transcriptional responses of diverse supraspinal cell types to spinal injury. Surprisingly, thoracic spinal injury triggered only modest changes in gene expression across all populations, including corticospinal tract (CST) neurons. Moreover, CST neurons also responded minimally to cervical injury but much more strongly to intracortical axotomy, including upregulation of numerous regeneration and apoptosis-related transcripts shared with injured DRG and RGC neurons. Thus, the muted response of CST neuron to spinal injury is linked to the injurys distal location, rather than intrinsic cellular characteristics. More broadly, these findings indicate that a central challenge for enhancing regeneration after a spinal injury is the limited sensing of distant injuries and the subsequent modest baseline neuronal response.

neuroscience↗

bioRxiv2020

Whole Exome Sequencing of a large family with Primary Open Angle Glaucoma reveals its vast complexity

PurposeTo identify the pathogenic variants associated with POAG by using Whole Exome Sequencing (WES) data of a large South Indian family. MethodsWe recruited a large five generation of South Indian family (n=84) with positive family history of POAG. All study participants had comprehensive ocular evaluation (of the 84, 19 study subjects were diagnosed as POAG). Sanger sequencing of the candidate genes associated with POAG (MYOC, OPTN and TBK1) showed no genetic variation in the POAG affected family members. Therefore, we performed whole exome sequencing (WES) for 16 samples including (9 POAG and 7 unaffected controls) and the data was analysed using an in-house pipeline for prioritizing the pathogenic variants based on its segregation among the POAG individual. ResultsWe identified one novel and five low-frequency pathogenic variants with consistent co-segregation in all affected individuals. The variant c.G3719A in RPGR-interacting domain of RPGRIP1 that segregated heterozygously with the six POAG cases is distinct from variants causing photoreceptor dystrophies, reported to affect the RPGR protein complex signaling in primary cilia. The cilia in TM cells has been reported to mediate the intraocular pressure (IOP) sensation. Furthermore, we identified a novel c.A1295G variant in Rho guanine nucleotide exchange factors Gene 40 (ARHGEF40) and likely pathogenic variant in the RPGR gene, suggesting that they may alter the RhoA activity essential for IOP regulation ConclusionOur study supports that low-frequency pathogenic variants in multiple genes and pathways probably affect the pathogenesis of Primary Open Angle Glaucoma in the large South Indian family.

genomics↗

bioRxiv2018

Performance Assessment of Variant Calling Pipelines using Human Whole Exome Sequencing and Simulated data

The whole exome sequencing (WES) is a time-consuming technology in the identification of clinical variants and it demands the accurate variant caller tools. The currently available tools compromise accuracy in predicting the specific types of variants. Thus, it is important to find out the possible combination of best aligner-variant caller tools for detecting SNVs and InDels separately. Moreover, many important aspects of InDel detection are not overlooked while comparing the performance of tools. One such aspect is the detection of InDels with respect to base pair length. To assess the performance of variant (especially InDels) caller in combination with different aligners, 20 automated pipelines were developed and evaluated using gold reference variant dataset (NA12878) from Genome in a Bottle (GiaB) consortium of human whole exome sequencing. Additionally, the simulated exome data from two human reference genome sequences (GRCh37 and GRCh38) were used to compare the performance of the pipelines. By analyzing various performance metrices, we observed that BWA and Novoalign aligners performed better with DeepVariant and SAMtools callers for detecting SNVs, and with DeepVariant and GATK for Indels. Altogether, DeepVariant with BWA and Novoalign performed best. Further, we showed that merging the top performing pipelines improved the accurate variant call set. Collectively, this study would help the investigators to effectively improve the sensitivity and accuracy in detecting specific variants.

bioinformatics↗