Biology subjects

Sanyal, K.

Publications and source records attributed to Sanyal, K..

At least 19 recordsLinked to original sources

bioRxiv2026

Elevated Levels of Mcm7 Disrupt Microtubule and Nucleolar Homeostasis to Drive Genome Instability and Cell Death

Overexpression of pre-replication complex (pre-RC) components is frequently associated with poor prognosis in many types of cancer, yet the mechanisms underlying their pathological effects remain unclear. Using the model yeast Candida albicans, we investigated the consequences of elevated Mcm7 levels, a conserved pre-RC subunit previously linked to chromosome instability (CIN). Unlike other pre-RC components, Mcm7 overexpression severely compromises nuclear integrity, resulting in chromatin fragmentation, DNA double-strand breaks, and cell death. Excess Mcm7 disrupts chromosome segregation by impairing microtubule function, disrupting centromere organization, generating abnormal spindle structures, and causing defective nuclear migration, collectively leading to mitotic failure. We further discovered ectopic accumulation of Mcm7 within the nucleolus, accompanied by widespread transcriptional disruption of nucleolus-associated genes. Supporting the relevance of these findings to human disease, cancer transcriptomic datasets reveal a strong association between MCM7 expression and nucleolar gene expression programs, while human cancer cell lines with higher MCM7 expression exhibit increased nucleolar number and size. Together, our findings identify Mcm7 as a previously unrecognized regulator of cytoskeletal and nucleolar homeostasis and uncover an unexpected mechanism by which replication factor dysregulation promotes CIN.

cell biology↗

bioRxiv2026

Evidence of residual Brugia malayi infection in TAS-III cleared areas of coastal Odisha: Findings from Molecular Xenomonitoring

BackgroundLymphatic filariasis (LF), caused by Wuchereria (W) bancrofti, Brugia malayi and Brugia (B) timori, remains a major public health problem known for its disfiguring and debilitating effects despite notable progress under the Global Program to Eliminate Lymphatic Filariasis (GPELF). Following recent national directives (2024) restructuring implementation units (IUs) to the block level, all TAS-cleared blocks now require re-evaluation using night blood surveys (NBS) or filarial test strip (FTS) kits. Molecular Xenomonitoring (MX) is recommended as a post-validation surveillance method for detecting active LF transmission in vectors. Therefore, an exploratory study was conducted in two coastal districts of Odisha, namely Jagatsinghpur and Puri, which cleared TAS-III, to investigate the presence of B. malayi and W. bancrofti infections in filaria-transmitting vectors. Methodology/Principal FindingsAdult female mosquitoes were collected from three villages across Jagatsinghpur and Puri districts during March-April 2025. Species were identified morphologically, segregated and pooled. The pooled samples were screened for the presence of filarial DNA using species-specific PCR assays. Of 1,518 collected adult female mosquitoes, 22.6% were Culex quinquefasciatus, 18.3% were Mansonia (Mn) annulifera, and 4.3% were Mansonia uniformis. Among 33 pools screened, six pools were positive for B. malayi DNA (18.18% pool positivity; infection rate 2.88%, 95% CI: 1.23-5.74), in Mn. annulifera, whereas W. bancrofti was not detected. Conclusions/SignificanceThe study provides the first molecular confirmation of B. malayi infection in Mn. annulifera, indicating a persistent Brugian transmission in Odisha even after the implementation of mass drug administration. The Study highlights MX as a sensitive, non-invasive surveillance tool for detecting residual infection in post-MDA and post-TAS settings. The study underscores the need for a standardized MX protocol and integration with entomological monitoring to sustain national LF elimination targets by 2027. Author SummaryLymphatic filariasis is a mosquito-borne disease that can cause severe, disfiguring swelling of the limbs and other lasting disabilities, and it remains a serious public health problem in India. National programmes in India are actively working to eliminate it by giving preventive medicines to communities, conducting surveys to confirm that transmission has ceased, and once an area passes, this treatment is withdrawn. However, it is not always clear whether the parasite has truly disappeared or is still lingering at very low levels. In this study, we searched for the parasite directly inside mosquitoes, an approach that does not require collecting blood from people. We sampled mosquitoes from two coastal districts of Odisha, India, that had already passed the required surveys and stopped treatment. We found the parasite Brugia malayi in Mansonia mosquitoes, the first time this has been shown using this molecular method in the region, although the more common filarial parasite was not detected. Our findings show that transmission can smoulder on even after an area is judged free of disease. Because India has no available rapid field test for this particular parasite, we argue that examining mosquitoes should become a routine safeguard for the countrys elimination effort.

zoology↗

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

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

Spatio-temporal chromosomal arrangements by late-replicating heterochromatin

Fungal centromeres are clustered near microtubule organizing centers to help adopt the Rabl chromosomal organization. The role of centromere clustering in driving large-scale changes in structural and functional chromatin assembly remains unclear. Here, using Hi-C and super-resolution microscopy, we show that cell cycle-dependent centromere declustering and clustering states in Cryptococcus neoformans drive global changes in the 3D genome architecture. Centromeres and telomeres are scattered around the nuclear periphery at interphaseG1, and this arrangement constrains the inter-arm interactions within a chromosome, providing a unique interphaseG1 chromosome organization. Moreover, centromeres and telomeres are organized as compartments, segregating them from active euchromatic regions. Polymer modeling reveals that the transition from the unclustered to clustered centromere state during the cell cycle involves changes from a globular to an elongated chromosome architecture. Strikingly, while clustered centromeres replicate early in most yeasts, C. neoformans centromeres replicate late in S-phase, hinting a possible link between centromere clustering dynamics and CEN DNA replication timing. Overall, our study uncovers several unique organizational principles governing the dynamic genome architecture in an evolutionarily diverged basidiomycete yeast. SignificanceChromosomes occupy the nuclear space in many ways. Primary chromosomal arrangements are such that centromere regions of different chromosomes either form a cluster, as in yeasts, or are scattered around the nuclear periphery, more common in metazoans. Exceptionally, centromeres show cell cycle stage-specific clustering in the basidiomycete fungus Cryptococcus neoformans. We show that the spatial positioning and the refractory nature of centromeres and telomeres shape the arrangement and large-scale organization of chromosomes in C. neoformans. Metazoan-like late-replicating centromeres in C. neoformans possibly favor the unclustered/scattered centromere state in S-phase, not commonly found in fungi. Our results not only highlight the remarkable genome plasticity of C. neoformans but also raise the possibility that centromere replication timing determines genome organization principles.

genomics↗

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↗

bioRxiv2025

The experimentally evolved fluconazole-resistant Clade II isolates of Candidozyma auris exhibit a distinct lipid compositional landscape, highlighting intra-clade sphingolipid heterogeneity

The intrinsic resistance of Candidozyma auris to antifungal drugs poses a major therapeutic challenge, with conventional resistance mechanisms providing only partial explanations. Sphingolipids (SLs), known for their interclade heterogeneity, play a crucial role in antifungal resistance. This study examined the SL landscape in two drug-susceptible clade II isolates, C-line and P-line, from distinct geographical origins, which were experimentally evolved to develop stable fluconazole (FLC) resistance. The progenitors displayed distinct SL profiles, P1 had higher PhytoCer and OHPhytoCer, indicating a more active acidic SL biosynthesis branch, whereas C1 exhibited elevated OHGlcCer, OHCer, and LCBs, reflecting a greater role of the neutral biosynthesis branch. The principal component analysis (PCA) also confirmed distinct segregation of the two progenitors. Upon evolution, P1.1 and C1.1 adaptors showed significant SL alterations. P1.1 exhibited PhytoCer enrichment, while C1.1 showed reduced OHGlcCer alongside increased PhytoCer, dhCer and OHPhytoCer levels. Notably, OHGlcCer remained unchanged in P1.1, whereas LCBs and OHPhytoCer decreased compared to P1. Despite these lineage-specific differences between the progenitors, both evolved replicates exhibited increased PhytoCer as a common denominator like what is also observed in clinical FLC-resistant isolates. These findings highlight intra-clade SL variability and suggest that specific SLs contribute to FLC resistance in C. auris.

microbiology↗

bioRxiv2024

Shugoshin maintains mitotic arrest in response to improper kinetochore-microtubule interactions independent of the Bub1-pH2A axis

During chromosome segregation, the spindle assembly checkpoint (SAC) detects errors in kinetochore-microtubule attachments. Timely activation and maintenance of the SAC until defects are corrected is essential for genome stability. Here, we show that shugoshin (Sgo1), a conserved tension-sensing protein, ensures the maintenance of SAC signals in response to unattached kinetochores during mitosis in a basidiomycete budding yeast Cryptococcus neoformans. Sgo1 maintains optimum levels of Aurora B kinase Ipl1 and protein phosphatase 1 (PP1) at kinetochores. The absence of Sgo1 results in the loss of Aurora BIpl1 with a concomitant increase in PP1 levels at kinetochores. This leads to a premature reduction in the kinetochore-bound Bub1 levels and early termination of the SAC signals. Intriguingly, the kinase function of Bub1 is dispensable for shugoshins subcellular localization. Sgo1 is predominantly localized to spindle pole bodies (SPBs) and along the mitotic spindle with a minor pool at kinetochores. In the absence of proper kinetochore-microtubule attachments, Sgo1 reinforces the Aurora B kinaseIpl1-PP1 phosphatase balance, which is critical for prolonged maintenance of the SAC response.

cell biology↗

bioRxiv2024

Expansion microscopy reveals unique ultrastructural features of pathogenic budding yeast species

Candida albicans is the most prevalent fungal pathogen isolated from patients with candidemia. As is the case for many other fungi, the complex life cycle of C. albicans has been challenging to study with high-resolution microscopy techniques due to its small size. We employed ultrastructure expansion microscopy (U-ExM) to directly visualise sub-cellular structures at high resolution in the C. albicans yeast and during its transition to hyphal growth. NHS-ester pan-labelling in combination with immunofluorescence (IF) provided the first comprehensive map of nucleolar and mitochondrial dynamics through the C. albicans cell cycle. Analysis of microtubules (MTs) and spindle pole bodies (SPBs) stained with marker proteins suggests that contrary to the pole-to-pole arrangement observed in Saccharomyces cerevisiae, C. albicans yeast cells display a unique side-by-side arrangement of SPBs with a short mitotic spindle and longer astral MTs (aMTs) at the pre-anaphase stage. Modifications to the established U-ExM protocol enabled the expansion of several medically relevant human fungal pathogens, revealing that the side-by-side SPB configuration is a plausible conserved feature shared by many fungal species. We highlight the power of U-ExM to investigate sub-cellular organisation and organellar dynamics at high resolution and low cost in poorly studied, medically relevant microbial pathogens.

cell biology↗

bioRxiv2023

Microevolution of clade II isolates of Candida auris highlights multifaceted intra-clade heterogeneity in acquiring resistance towards amphotericin B

Candida auris exhibits high-level resistance to amphotericin B (AmB). Mechanisms such as ergosterol biosynthesis malfunction, oxidative damage mismanagement, and increased drug efflux contribute to AmB resistance in C. auris. In this study, we experimentally evolved two East Asian drug-susceptible clade II isolates of C. auris (P2428 and CBS10913T) isolated from different geographical locations to develop resistance against AmB. We analysed alterations in karyotype, genome sequence, and gene expression profiles to uncover the mechanisms driving AmB resistance. The independently evolved clade II adaptors displayed up to 4-16-fold higher MIC50, as compared to the parental cells. AOX2 (alternative oxidase) and the cell wall integrity pathway have been identified as critical in the development of AmB resistance. However, we noted certain intra-clade heterogeneity in the associated mechanisms. While in P2428 adaptors (P-lines), the ergosterol and sphingolipid pathways appear to play a crucial role, this was not the case for CBS10913T adaptors (A-lines), which acquired resistance independent of lipid-associated changes. The transcriptomic, WGS, and phenotypic analyses also confirm that the evolved AmB-resistant isolates follow distinct trajectories for adaptation, Furthermore, unlike the fluconazole-resistant isolates, as reported previously, changes in ploidy do not seem to contribute to the differential mechanisms of AmB resistance. Overall, this study not only provides insights into the mechanisms and pathways involved in AmB resistance but also highlights intra-clade-heterogeneity that exists within clade II of C. auris. ImportanceCandida auris demonstrates significant resistance to amphotericin B (AmB) that stems from factors like alteration of ergosterol biosynthesis, perturbation of the oxidative damage response, etc. A comprehensive understanding of underlying mechanisms can be studied in a holistic manner by subjecting resistant as well as susceptible clinical isolates to a comparative genome-level analysis. An alternate and more dynamic approach is to expose susceptible isolates to a certain concentration of drug which is not lethal but can trigger the resistance mechanisms. In the present study, we evolved C. auris towards AmB and observed novel and differential mechanisms of resistance development, in two different isolates despite belonging to the same clade. This study provides insights into the intra-clade heterogeneous behavior of C. auris towards AmB.

microbiology↗

bioRxiv2023

Genetic and genomic analysis of Malassezia reveals transitions in mating-type locus chromosomal organization and early steps in sexual reproduction

Fungi in the basidiomycete genus Malassezia are the most prevalent eukaryotic microbes resident on the skin of human and other warm-blooded animals and have been implicated in skin diseases and systemic disorders. Analysis of Malassezia genomes revealed that key adaptations to the skin microenvironment have a direct genomic basis, and the identification of mating/meiotic genes suggests a capacity to reproduce sexually, even though no sexual cycle has yet been observed. In contrast to other bipolar or tetrapolar basidiomycetes that have either two linked mating-type-determining (MAT) loci or two MAT loci on separate chromosomes, in Malassezia species studied thus far the two MAT loci are arranged in a pseudobipolar configuration (linked on the same chromosome but capable of recombining). By incorporating newly generated chromosome-level genome assemblies, and an improved Malassezia phylogeny, we infer that the pseudobipolar arrangement was the ancestral state of this group and revealed six independent transitions to tetrapolarity, seemingly driven by centromere fission or translocations in centromere- flanking regions. Additionally, in an approach to uncover a sexual cycle, Malassezia furfur strains were engineered to express different MAT alleles in the same cell. The resulting strains produce hyphae reminiscent of early steps in sexual development and display upregulation of genes associated with sexual development as well as others encoding lipases and a protease potentially relevant for pathogenesis of the fungus. Our study reveals a previously unseen genomic relocation of mating-type loci in fungi and provides insight towards the discovery of a sexual cycle in Malassezia, with possible implications for pathogenicity. Significance StatementMalassezia, the dominant fungal group of the mammalian skin microbiome, is associated with numerous skin disorders. Sexual development and yeast-to-hyphae transitions, governed by genes at two mating-type (MAT) loci, are thought to be important for fungal pathogenicity. However, Malassezia sexual reproduction has never been observed. Here, we used chromosome-level assemblies and comparative genomics to uncover unforeseen transitions in MAT loci organization within Malassezia, possibly related with fragility of centromeric-associated regions. Additionally, by expressing different MAT alleles in the same cell, we show that Malassezia can undergo hyphal development and this phenotype is associated with increased expression of key mating genes along with other genes known to be virulence factors, providing a possible connection between hyphal development, sexual reproduction, and pathogenicity.

genetics↗

bioRxiv2022

Regional centromeres protect organisms from lethal mutations

The Dam1 complex is essential for mitotic progression across evolutionarily divergent fungi. Upon analyzing amino acid (aa) sequences of Dad2, a Dam1 complex subunit, we identified a conserved 10-aa-long Dad2 signature sequence (DSS). An arginine residue (R126) in the DSS is essential for viability in Saccharomyces cerevisiae that possesses point centromeres. The corresponding arginine residues are functionally important but not essential for viability in Candida albicans and Cryptococcus neoformans, both carry several kilobases long regional centromeres. The purified recombinant Dam1 complex containing either Dad2{Delta}DSS or Dad2R126A failed to bind microtubules (MTs) or form any visible rings like the wild-type complex. Intriguingly, functional analysis revealed that the requirement of the conserved arginine residue for chromosome biorientation and mitotic progression reduced with increasing centromere length. We propose that plasticity of the invariant arginine of Dad2 in organisms with regional centromeres is achieved by conditional elevation of the kinetochore protein(s) to enable multiple kinetochore MTs (kMTs) to bind to each chromosome. The capacity of a chromosome to bind multiple kMTs may mask deleterious effects of such lethal mutations.

genetics↗

bioRxiv2021

Autophagy-related protein Atg11 preserves asymmetric inheritance of spindle microtubule-organizing centers

Emerging studies hint at the roles of autophagy-related proteins in various cellular processes in a eukaryotic cell. To understand if autophagy-related proteins influence genome stability, we examined a cohort of 35 autophagy mutants in Saccharomyces cerevisiae. We observed cells lacking Atg11 show poor mitotic stability of minichromosomes. Atg11 molecules dynamically localize to the spindle pole bodies (SPBs). Loss of Atg11 leads to a delayed cell cycle progression. Such cells accumulate at metaphase at an elevated temperature that is relieved when the spindle assembly checkpoint is inactivated. Indeed, atg11{Delta} cells have stabilized securin levels, that prevent anaphase onset, confirming chromosome biorientation defects associated with the mutant. Atg11 functions in the Kar9-dependent spindle positioning pathway and maintains Kar9 asymmetry by facilitating proper dynamic instability of astral microtubules (aMTs). Taken together, this study uncovers a non-canonical role of Atg11 in facilitating MT dynamics crucial for chromosome segregation.

genetics↗

bioRxiv2021

A phylogenetically-restricted essential cell cycle progression factor in the human pathogen Candida albicans

Chromosomal instability in fungal pathogens caused by cell division errors is associated with antifungal drug resistance. To identify mechanisms underlying such instability and to uncover new potential antifungal targets, we conducted an overexpression screen monitoring chromosomal stability in the human fungal pathogen Candida albicans. Analysis of ~1000 genes uncovered six chromosomal stability (CSA) genes, five of which are related to cell division genes in other organisms. The sixth gene, CSA6, is selectively present in the CUG-Ser clade species that includes C. albicans and other human fungal pathogens. The protein encoded by CSA6 localizes to the spindle pole bodies, is required for exit from mitosis, and induces a checkpoint-dependent metaphase arrest upon overexpression. Together, Csa6 defines an essential CUG-Ser fungal clade-specific cell cycle progression factor, highlighting the existence of phylogenetically-restricted cell division genes which may serve as potential unique therapeutic targets. TeaserCsa6 is essential for mitotic progression and mitotic exit in the human fungal pathogen Candida albicans.

cell biology↗

bioRxiv2021

Functional and comparative genome analysis reveals clade-specific genome innovations in the killer fungus Candida auris

The thermotolerant multidrug-resistant ascomycete Candida auris rapidly emerged since 2009 and simultaneously evolved in different geographical zones worldwide, causing superficial as well as systemic infections. The molecular events that orchestrated this sudden emergence of the killer fungus remain mostly elusive. Here, we identify centromeres in C. auris and related species, using a combined approach of chromatin immunoprecipitation and comparative genomic analyses. We find that C. auris and multiple other species in the Clavispora/Candida clade shared a conserved small regional centromere landscape lacking pericentromeres. Further, a centromere inactivation event led to karyotypic alterations in this species complex. Inter-species genome analysis identified several structural chromosomal changes around centromeres. In addition, centromeres are found to be rapidly evolving loci among the different geographical clades of the same species of C. auris. Finally, we reveal an evolutionary trajectory of the unique karyotype associated with clade 2 that consists of the drug susceptible isolates of C. auris.

genomics↗

bioRxiv2020

Shugoshin promotes efficient activation of spindle assembly checkpoint and timely spindle disassembly

Shugoshin proteins are evolutionary conserved across eukaryotes with some species-specific cellular functions ensuring the fidelity of chromosome segregation. Shugoshin being present at various subcellular locales, acts as an adaptor to mediate various protein-protein interactions in a spatio-temporal manner. Here, we characterize shugoshin (Sgo1) in the human fungal pathogen, Candida albicans. Interestingly, we discover a novel in vivo localization of Sgo1 along the length of the mitotic spindle. Further, Sgo1 performs a hitherto unknown function of facilitating timely disassembly of spindle in this organism. We observe that Sgo1 retains its centromeric localization and performs its conserved functions that include regulating the centromeric condensin localization, chromosome passenger complex (CPC) maintenance and sister chromatid biorientation. We identify novel roles of Sgo1 as a spindle assembly checkpoint (SAC) component with functions in maintaining the SAC proteins, Mad2 and Bub1, at the kinetochores, in response to faulty kinetochore-microtubule attachments. These findings provide an excellent evidence of the functional rewiring of shugoshin in maintaining genomic stability.

cell biology↗

bioRxiv2020

Vacuolar transporter Mnr2 safeguards mitochondrial integrity in aged cells

Aging is associated with altered mitochondrial function. Mitochondrial function is dependent on the magnesium (Mg+2) ion flux. The molecular mechanism underlying Mg+2 homeostasis, especially during aging has not been well understood. We previously demonstrated that the absence of a vacuolar ion transporter Mnr2 accelerates cell death in the older part of the colony in Magnaporthe oryzae presumably due to an altered Mg+2 homeostasis. Localization of Mnr2 as dynamic puncta at the vacuolar membrane especially in the older Magnaporthe cells further suggests its association with aged cells. Interestingly, such vacuolar Mnr2 puncta colocalized with the filamentous mitochondria in the aged cells. Further, we show that aged mnr2{Delta} null cells displayed loss of integrity of mitochondria and vacuoles. Remarkably, exogenously added Mg+2 restored the mitochondrial structure as well as improved the lifespan of mnr2{Delta} null cells. Thus, we uncover a mechanism of maintenance of mitochondrial integrity and function by the ion transporter Mnr2-based Mg+2 homeostasis during aging.

cell biology↗

bioRxiv2020

Spatial proximity of homologous centromere DNA sequences facilitated karyotype diversity and seeding of evolutionary new centromeres

Centromeres of Candida albicans form on unique and different DNA sequences but a closely related species, Candida tropicalis, possesses homogenized inverted repeat (HIR)-associated centromeres. To investigate the mechanism of centromere-type transition, we improved the fragmented genome assembly and constructed a chromosome-level genome assembly of C. tropicalis by employing PacBio sequencing, chromosome conformation capture sequencing (3C-seq), chromoblot, and genetic analysis of engineered aneuploid strains. Further, we analyzed the 3D genome organization using 3C-seq data, which revealed spatial proximity among the centromeres as well as telomeres of seven chromosomes in C. tropicalis. Intriguingly, we observed evidence of inter-centromeric translocations in the common ancestor of C. albicans and C. tropicalis. Identification of putative centromeres in closely related Candida sojae, Candida viswanathii and Candida parapsilosis indicates loss of ancestral HIR-associated centromeres and establishment of evolutionary new centromeres (ENCs) in C. albicans. We propose that spatial proximity of the homologous centromere DNA sequences facilitated karyotype rearrangements and centromere type transitions in human pathogenic yeasts of the CUG-Ser1 clade.

genetics↗