Biology subjects

Khan, M. M.

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

33 records · Page 2Linked to original sources

bioRxiv2023

Implications of variable synaptic weights for rate and temporal coding of cerebellar outputs

Purkinje cell (PC) synapses onto cerebellar nuclei (CbN) neurons convey signals from the cerebellar cortex to the rest of the brain. PCs are inhibitory neurons that spontaneously fire at high rates, and many uniform sized PC inputs are thought to converge onto each CbN neuron to suppress or eliminate firing. Leading theories maintain that PCs encode information using either a rate code, or by synchrony and precise timing. Individual PCs are thought to have limited influence on CbN neuron firing. Here, we find that single PC to CbN synapses are highly variable in size, and using dynamic clamp and modelling we reveal that this has important implications for PC-CbN transmission. Individual PC inputs regulate both the rate and timing of CbN firing. Large PC inputs strongly influence CbN firing rates and transiently eliminate CbN firing for several milliseconds. Remarkably, the refractory period of PCs leads to a brief elevation of CbN firing prior to suppression. Thus, PC-CbN synapses are suited to concurrently convey rate codes, and generate precisely-timed responses in CbN neurons. Variable input sizes also elevate the baseline firing rates of CbN neurons by increasing the variability of the inhibitory conductance. Although this reduces the relative influence of PC synchrony on the firing rate of CbN neurons, synchrony can still have important consequences, because synchronizing even two large inputs can significantly increase CbN neuron firing. These findings may be generalized to other brain regions with highly variable sized synapses.

neuroscience↗

bioRxiv2023

HIC1 interacts with FOXP3 multi-protein complex: a novel mechanism to regulate human regulatory T cell differentiation and function

Transcriptional repressor, hypermethylated in cancer 1 (HIC1) participates in a range of important biological processes, such as tumor repression, immune suppression, embryonic development and epigenetic gene regulation. Further to these, we previously demonstrated that HIC1 provides a significant contribution to the function and development of regulatory T (Treg) cells. However, the mechanism by which it regulates these processes was not apparent. To address this question, we used affinity-purification mass spectrometry to characterize the HIC1 Interactome in human Treg cells. Altogether 61 high-confidence interactors were identified, including IKZF3, which is a key transcription factor in the development of Treg cells. The biological processes associated with these interacting proteins include protein transport, mRNA processing, non-coding (ncRNA) transcription and RNA metabolism. The results revealed that HIC1 is part of a FOXP3-RUNX1-CBFB protein complex that regulates Treg signature genes thus improving our understanding of HIC1 function during early Treg cell differentiation. HighlightsO_LISystematic characterization of HIC1 interactome in regulatory T cells by Affinity Purification-Mass Spectrometry C_LIO_LIHIC1 binds to the RUNX1 promoter and regulates its expression C_LIO_LIHIC1-a part of FOXP3-RUNX1-CBFB transcriptional complex C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=37 SRC="FIGDIR/small/540505v1_ufig1.gif" ALT="Figure 1"> View larger version (14K): org.highwire.dtl.DTLVardef@1fcb119org.highwire.dtl.DTLVardef@cf1397org.highwire.dtl.DTLVardef@10f512forg.highwire.dtl.DTLVardef@9ae94e_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2023

Dextromethorphan inhibits collagen transport in the endoplasmic reticulum eliciting an anti-fibrotic response in ex-vivo and in vitro models of pulmonary fibrosis

Excessive deposition of fibrillar collagen in the interstitial extracellular matrix (ECM) of human lung tissue causes fibrosis, which can ultimately lead to organ failure. Despite our understanding of the molecular mechanisms underlying the disease, a cure for pulmonary fibrosis has not yet been found. In this study, we screened an FDA-approved drug library containing 712 drugs and found that Dextromethorphan (DXM), a cough expectorant, significantly reduces the amount of excess fibrillar collagen deposited in the ECM in in-vitro cultured primary human lung fibroblasts (NHLF) and ex-vivo cultured human precision-cut lung slice (hPCLS) models of lung fibrosis. Reduced extracellular fibrillar collagen levels in the ECM upon DXM treatment are due to a reversible trafficking inhibition of collagen type I (COL1) in the endoplasmic reticulum (ER) in TANGO1 and HSP47 positive structures. Mass spectrometric analysis shows that DXM causes hyper-hydroxylation of proline and lysine residues on Collagen (COL1, COL3, COL4, COL5, COL7, COL12) and Latent-transforming growth factor beta-binding protein (LTBP1 and LTBP2) peptides coinciding with their secretion block. In addition, thermal proteome profiling of cells treated with DXM shows increased thermal stability of prolyl-hydroxylases such as P3H2, P3H3, P3H4, P4HA1 and P4HA2, suggesting a change in activity. Transcriptome analysis of pro-fibrotic stimulated NHLFs and hPCLS upon DXM treatment showed activation of an anti-fibrotic program via regulation of pathways such as those involved in the MMP-ADAMTS axis, WNT, and fibroblast-to-myofibroblast differentiation. Taken together, the data obtained from both in-vitro and ex-vivo models of fibrogenesis show that Dextromethorphan has potent anti-fibrotic activity by efficient inhibition of COL1 membrane trafficking in the ER.

cell biology↗

bioRxiv2023

Total RNA sequencing reveals gene expression and microbial alterations shared by oral pre-malignant lesions and cancer.

Head and neck cancers are a complex malignancy comprising multiple anatomical sites, with cancer of the oral cavity ranking among the deadliest and most disfiguring cancers globally. Oral cancer (OC) constitutes a subset of head and neck cancer cases, presenting primarily as tobacco-and alcohol-associated oral squamous cell carcinoma (OSCC), with a 5-year survival rate of [~]65%, partly due to the lack of early detection and effective treatments. OSCC arises from premalignant lesions (PMLs) in the oral cavity through a multi-step series of clinical and histopathological stages, including varying degrees of epithelial dysplasia. To gain insights into the molecular mechanisms associated with the progression of PMLs to OSCC, we profiled the whole transcriptome of 66 human PMLs comprising leukoplakia with dysplasia and hyperkeratosis non-reactive (HkNR) pathologies, alongside healthy controls and OSCC. Our data revealed that PMLs were enriched in gene signatures associated with cellular plasticity, such as partial EMT (p-EMT) phenotypes, and with immune response. Integrated analyses of the host transcriptome and microbiome further highlighted a significant association between differential microbial abundance and PML pathway activity, suggesting a contribution of the oral microbiome towards PML evolution to OSCC. Collectively, this study reveals molecular processes associated with PML progression that may help early diagnosis and disease interception at an early stage. AUTHOR SUMMARYPatients harboring oral premalignant lesions (PMLs) have an increased risk of developing oral squamous cell carcinoma (OSCC), but the underlying mechanisms driving transformation of PMLs to OSCC remain poorly understood. In this study, Khan et al., analyzed a newly generated dataset of gene expression and microbial profiles of oral tissues from patients diagnosed with PMLs from differing histopathological groups, including hyperkeratosis not reactive (HkNR) and dysplasia, comparing these profiles with OSCC and normal oral mucosa. Significant similarities between PMLs and OSCC were observed, with PMLs manifesting several cancer hallmarks, including oncogenic and immune pathways. The study also demonstrates associations between the abundance of multiple microbial species and PML groups, suggesting a potential contribution of the oral microbiome to the early stages of OSCC development. The study offers insights into the nature of the molecular, cellular and microbial heterogeneity of oral PMLs and suggests that molecular and clinical refinement of PMLs may provide opportunities for early disease detection and interception. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=94 SRC="FIGDIR/small/534064v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@86cf7org.highwire.dtl.DTLVardef@129e6d1org.highwire.dtl.DTLVardef@1f0ae31org.highwire.dtl.DTLVardef@3c4d67_HPS_FORMAT_FIGEXP M_FIG C_FIG

genomics↗

bioRxiv2023

In Silico Evaluation of Biomarker Genes for Melanoma Carcinoma

ABSTRACTSMelanoma skin cancer is a primary cutaneous malignancy. Melanoma cancer of the skin cell is one of the major skin cancer worldwide, ranking first in frequency. Melanoma skin cancer has been strongly associated with psoriasis. Here, we use computational methods in an effort to identify possible biomarkers for psoriasis related Melanoma skin cancer. To do this, we downloaded gene expression microarray data from the GEO (Gene Expression Omnibus) database in the GSE series: GSE14905 and pre-processed it in the Bioconductor repository for R. The data was screened for DEGs using a rigorous methodology, which included the use of statistical testing methodologies and tools (Differentially Expressed Genes). Psoriasis has 6749 up-regulated genes and 7142 down-regulated genes. Psoriasis DEGs were combined with the NCG dataset resulting 874 up-regulated genes and 74 down-regulated genes for an in depth analysis of how differential expression can lead to malignancy. we used stringDB diseases dataset in Cytoscape to generate network of melanoma proteins, which were further mapped to DEGs and igraph to construct a GRN. In addition, module level analysis was carried out because of the benefits it provides in terms of stability and comprehension of intricate GRNs, resulting 17 biomarkers (17 up-regulated). There is an emphasis on the networks topology as well. The findings suggest that the network has a hierarchical structure. Additionally, survival analysis of 8 biomarkers results obtained from intersection mapping of skin cancer stringDB and biomarkers, was carried out. Significant enrichment of KEGG pathways was found. They also illuminate the interplay between biomarkers whose upregulation may lead to melanoma skin cancer. These findings may inform future investigations and the identification of potential therapeutic targets for this condition as well as shows the potential link between psoriasis and melanoma.

cancer biology↗

bioRxiv2022

The Golgi complex is a regulatory hub for homologous recombination-mediated DNA repair.

The Golgi complex is a key organelle of the secretory pathway, but also serves as a critical hub for maintaining cellular homeostasis, orchestrating various signalling pathways and essential cellular processes such as membrane trafficking and post-translational modifications. Despite its central role, the communication between the Golgi and the cell nucleus has remained largely unexplored. To bridge this gap, we have analysed and siRNA-validated localisation data of the Human Protein Atlas, finding an unexpected and significant level of interconnectivity between the proteomes of the Golgi complex and nucleus, including an intriguing involvement in DNA repair processes. Here, we uncovered a cluster of DNA repair proteins present in distinct sub-Golgi localisations as well as in the nuclear compartment. In response to genotoxic stress these proteins redistribute dynamically between the Golgi complex and the nucleus, with the specific type of DNA injury influencing this distribution pattern. To probe this Golgi-nucleus link, we examined the Homologous Recombination (HR) regulator RAD51C and find that DNA damage triggers ATM-dependent release of a Giantin-tethered Golgi pool and Importin-{beta}-dependent nuclear import, where repair-associated nuclear foci form. Downregulation of Giantin prematurely releases RAD51C, producing RAD51C nuclear foci lacking key HR markers, reducing ATM activation, elevating genome instability, and accelerating cell proliferation. These findings support a timing-based pathway in which the Golgi acts as a spatiotemporal coordination node for HR regulators and other DDR factors. Our study sheds light on the dynamic interplay between the Golgi and the nucleus in safeguarding genomic stability while maintaining the delicate balance of cellular homeostasis.

cell biology↗

bioRxiv2022

Quantitative imaging reveals PI3Kδ inhibition reduces rhinovirus-induced damage of small airway epithelia in ex vivo cultured human precision cut lung slices from COPD patients

Chronic obstructive pulmonary disease (COPD) is one of the major causes of disability and death worldwide and a significant risk factor for respiratory infections. Rhinoviral infections are the most common trigger of COPD exacerbations which lead to a worsening of disease symptoms, decline in lung function and increased mortality. The lack of suitable disease models to study the relevant cellular and molecular mechanism hinders the discovery of novel medicines that prevent disease progression in exacerbating COPD patients. We used quantitative multi-color imaging of COPD and control patient derived human precision-cut lung slices (hPCLS) to study the impact of rhinovirus infection on the structure and function of the small airway epithelium. Data analysis highlighted that COPD-derived hPCLS have a higher cellular density and basal cell hyperplasia, more unciliated airway surface areas with mucus overproduction, and shorter cilia length compared to control hPCLS. In response to rhinovirus 16 infection, COPD-derived hPCLS secreted higher amounts of pro-inflammatory cytokines and displayed decreased epithelial integrity and reduced airway ciliation. Finally, treatment with a selective PI3K{delta} inhibitor reduced secretion of rhinovirus-induced cytokines and ameliorated rhinovirus-induced damage to COPD small airway epithelia. Thus, these data demonstrate the potential of quantitative imaging to assess complex airway functions in a patient-derived lung tissue model system, and indicate that targeting PI3K{delta} might be a promising therapeutic opportunity to limit rhinovirus-induced airway damage in exacerbating COPD patients. SummaryPI3K{delta} inhibition reduces rhinovirus-mediated damage of small airway epithelia from chronic obstructive pulmonary disease (COPD) patients

pathology↗

bioRxiv2021

SOCS3-mediated activation of p53-p21-NRF2 axis and cellular adaptation to oxidative stress in SOCS1-deficient hepatocellular carcinoma

SOCS1 and SOCS3 genes, frequently repressed in hepatocellular carcinoma (HCC), function as tumor suppressors in hepatocytes. However, TCGA transcriptomic data revealed that SOCS1-low/SOCS3-high specimens displayed more aggressive HCC than SOCS1-low/SOCS3-low cases. We show that hepatocyte-specific Socs1-deficient livers upregulate Socs3 expression following genotoxic stress. Whereas deletion of Socs1 or Socs3 increased HCC susceptibility, ablation of both genes attenuated HCC growth. SOCS3 promotes p53 activation in SOCS1-deficient livers, leading to increased expression of CDKN1A (p21WAF1/CIP1), which coincides with elevated expression and transcriptional activity of NRF2. Deleting Cdkn1a in SOCS1-deficient livers diminished NRF2 activation, oxidative stress and HCC progression. Elevated CDKN1A expression and enrichment of antioxidant response genes also characterized SOCS1-low/SOCS3-high HCC. SOCS1 expression in HCC cell lines reduced oxidative stress, p21 expression and NRF2 activation. Our findings demonstrate that SOCS1 controls the oncogenic potential of SOCS3-driven p53-p21-NRF2 axis and suggest that NRF2-mediated antioxidant response represents a drug target in SOCS1-deficient HCC.

cancer biology↗

bioRxiv2021

Unusually slow spike frequency adaptation in deep cerebellar nuclei neurons preserves linear transformations on the sub-second time scale

Purkinje cells (PCs) are spontaneously active neurons of the cerebellar cortex that inhibit glutamatergic projection neurons within the deep cerebellar nuclei (DCN) that in turn provide the primary cerebellar output. Brief reductions in PC firing rapidly increase DCN neuron firing. However, prolonged reductions in PC inhibition, as seen in some disease states, certain types of transgenic mice, and in acute slices of the cerebellum, do not evoke large sustained increases in DCN firing. Here we test whether there is a mechanism of spike-frequency adaptation in DCN neurons that could account for these properties. We find that prolonged optogenetic suppression of PC synapses in vivo transiently elevates PC firing that strongly adapts within ten seconds. We perform current-clamp recordings at near physiological temperature in acute brain slices to examine how DCN neurons respond to prolonged depolarizations. Adaptation in DCN neurons is exceptionally slow and bidirectional. A depolarizing current step evokes large initial increases in firing that decay to less than 20% of the initial increase within approximately ten seconds. Such slow adaptation could allow DCN neurons to adapt to prolonged changes in PC firing while maintaining their linear firing frequency-current relationship on subsecond time scales.

neuroscience↗

bioRxiv2021

Bidirectional cooperation between Ubtf1 and SL1 determines RNA Polymerase I promoter recognition in cell and is negatively affected in the UBTF-E210K neuroregression syndrome.

Transcription of the [~]200 mouse and human ribosomal RNA genes (rDNA) by RNA Polymerase I (RPI/PolR1) accounts for 80% of total cellular RNA, around 35% of all nuclear RNA synthesis, and determines the cytoplasmic ribosome complement. It is therefore a major factor controlling cell growth and its misfunction has been implicated in hypertrophic and developmental disorders. Activation of each rDNA repeat requires nucleosome replacement by the architectural multi-HMGbox factor UBTF to create a 15kbp nucleosome free region (NFR). Formation of this NFR is also essential for recruitment of the TBP-TAFI factor SL1 and for preinitiation complex (PIC) formation at the gene and enhancer-associated promoters of the rDNA. However, these promoters show little sequence commonality and neither UBTF nor SL1 display significant DNA sequence binding specificity, making what drives PIC formation a mystery. Here we show that cooperation between SL1 and the longer UBTF1 splice variant generates the specificity required for rDNA promoter recognition in cell. We find that conditional deletion of the Taf1b subunit of SL1 causes a striking depletion UBTF at both rDNA promoters but not elsewhere across the rDNA. We also find that while both UBTF1 and -2 variants bind throughout the rDNA NFR, only UBTF1 is present with SL1 at the promoters. The data strongly suggest an induced-fit model of RPI promoter recognition in which UBTF1 plays an architectural role. Interestingly, a recurrent UBTF-E210K mutation and the cause of a pediatric neurodegeneration syndrome provides indirect support for this model. E210K knock-in cells show enhanced levels of the UBTF1 splice variant and a concomitant increase in active rDNA copies. In contrast, they also display reduced rDNA transcription and promoter recruitment of SL1. We suggest the underlying cause of the UBTF-E210K syndrome is therefore a reduction in cooperative UBTF1-SL1 promoter recruitment that may be partially compensated by enhanced rDNA activation.

molecular biology↗

bioRxiv2021

A high throughput SEC23 functional interaction screen reveals a role for focal adhesion and extracellular matrix signalling in the regulation of COPII subunit SEC23A

Proteins that enter the secretory pathway are transported from their place of synthesis in the Endoplasmic Reticulum to the Golgi complex by COPII coated carriers. The components of the COPII transport machinery have been well characterized, but the network of proteins that regulate these components in response to extracellular cues have remained largely elusive. The discovery of such regulatory proteins is crucial for understanding how cells integrate extracellular and intracellular information to fine-tune membrane traffic in the secretory pathway. A key group of proteins that plays a central role in the regulation of membrane traffic is associated with the cytoskeleton. Using high throughput microscopy of the well-established VSVG transport from the ER to the plasma membrane, we comprehensively screened 378 cytoskeleton-associated proteins for their functional interaction with the COPII components SEC23A and SEC23B using a double knockdown approach. Ranking of the transport effectors identified 20 cytoskeleton-associated proteins as the strongest functional interactors of SEC23, most of them not previously associated with the secretory pathway. Knockdown of a subgroup of these interactors (FERMT2, MACF1, MAPK8IP2, NGEF, PIK3CA, ROCK1), associated with cell adhesion, not only induced changes in focal adhesions and the expression of adhesion-related genes but led to the specific downregulation of SEC23A, a SEC23 paralogue that has been implicated in the secretion of extracellular matrix (ECM) components. Furthermore, SEC23A downregulation could also be recapitulated by plating cells on ECM and was dependent on focal adhesions function. Altogether, our results identify a network of cytoskeleton-associated proteins connecting focal adhesions and ECM-related signalling with the gene expression of the COPII secretory machinery.

cell biology↗

bioRxiv2021

Quantitative analysis and genome-scale modeling of human CD4+ T-cell differentiation reveals subset-specific regulation of glycosphingolipid pathways

T-cells are sentinels of adaptive cell-mediated immune responses. T-cell activation, proliferation and differentiation involves metabolic reprogramming involving the interplay of genes, proteins and metabolites. Here, we aim to understand the metabolic pathways involved in the activation and functional differentiation of human CD4+ T-cell subsets (Th1, Th2, Th17 and iTregs). We combined genome-scale metabolic modeling, gene expression data, targeted and non-targeted lipidomics experiments, together with in vitro gene knockdown experiments and showed that human CD4+ T-cells undergo specific metabolic changes during activation and functional differentiation. In addition, we identified and confirmed the importance of ceramide and glycosphingolipid synthesis pathways in Th17 differentiation and effector functions. Finally, through in vitro gene knockdown experiments, we substantiated the requirement of serine palmitoyl transferase (SPT), a de novo sphingolipid pathway in the expression of proinflammatory cytokine (IL17A and IL17F) by Th17 cells. Our findings may provide a comprehensive resource for identifying CD4+ T-cell-specific targets for their selective manipulation under disease conditions, particularly, diseases characterized by an imbalance of Treg / Th17 cells. Our data also suggest a role for elevated levels of ceramides in conditions comorbid with these diseases, e.g., obesity and insulin resistance.

immunology↗

bioRxiv2019

Multiomic and quantitative label-free microscopy-based analysis of ex vivo culture and TGFbeta1 stimulation of human precision-cut lung slices

Fibrosis can affect any organ resulting in the loss of tissue architecture and function with often life-threatening consequences. Pathologically, fibrosis is characterised by expansion of connective tissue due to excessive deposition of extracellular matrix proteins (ECM), including the fibrillar forms of collagen. A significant hurdle for discovering cures for fibrosis is the lack of suitable models and techniques to quantify mature collagen deposition in tissues. Here we have extensively characterized an ex-vivo cultured human lung derived, precision-cut lung slices model (hPCLS) using live fluorescence light microscopy as well as mass spectrometry-based techniques to obtain a proteomic and metabolomic fingerprint. Using an integrated approach of multiple readouts such as quantitative label-free Second Harmonic Generation (SHG) imaging to measure fibrillar collagen in the extracellular matrix and ELISA-based methods to measure soluble ECM biomarkers, we investigated TGFbeta1-mediated pro-fibrotic signalling in hPCLS. We demonstrate that hPCLS are viable and metabolically active with mesenchymal, epithelial, endothelial, and immune cells surviving for at least two weeks in ex vivo culture. Analysis of hPCLS-conditioned supernatants showed strong induction of ECM synthesis proteins P1NP and fibronectin upon TGFb stimulation. Importantly, this effect translated into an increased deposition of fibrillar collagen in ECM of cultured hPCLS as measured by a novel quantitative SHG-based imaging method only following addition of a metalloproteinase inhibitor (GM6001). Together the data show that an integrated approach of measuring soluble pro-fibrotic markers and quantitative SHG-based analysis of fibrillar collagen is a valuable tool for studying pro-fibrotic signalling and testing anti-fibrotic agents.

physiology↗

bioRxiv2019

Protein Interactome of the Cancerous Inhibitor of Protein Phosphatase 2A (CIP2A) in Th17 Cells

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is involved in immune response, cancer progression, and in Alzheimers disease. However, an understanding of the mechanistic basis of its function in this wide spectrum of physiological and pathological processes is limited due to its poorly characterized interaction networks. Here we present the first systematic characterization of the CIP2A interactome by affinity-purification mass spectrometry combined with validation by selected reaction monitoring targeted mass spectrometry (SRM-MS) analysis in Th17 cells. In addition to the known regulatory subunit of protein phosphatase PP2A, the catalytic subunit of protein PP2A was found to be interacting with CIP2A. Furthermore, the regulatory (PPP1R18, and PPP1R12A) and catalytic (PPP1CA) subunits of phosphatase PP1 were identified among the top novel CIP2A interactors. Evaluation of the ontologies associated with the proteins in this interactome revealed that they were linked with RNA metabolic processing and splicing, protein traffic, cytoskeleton regulation and ubiquitin-mediated protein degradation processes. Taken together, this network of protein-protein interactions will be important for understanding and further exploring the biological processes and mechanisms regulated by CIP2A both in physiological and pathological conditions.\n\nHighlights{blacksquare} The first characterisation of the CIP2A interactome in Th17 cells.\n{blacksquare}Key interactions were validated by targeted SRM-MS proteomics, western blot and confocal microscopy.\n{blacksquare}Pathway analysis of the interactome revealed interrelationships with proteins across a broad range of processes, in particular associated with mRNA processing.

systems biology↗

bioRxiv2017

Mechanistic view and genetic control of DNA recombination during meiosis

Meiotic recombination is essential for fertility and allelic shuffling. Canonical recombination models fail to capture the observed complexity of meiotic recombinants. Here we revisit these models by analyzing meiotic heteroduplex DNA tracts genome-wide in combination with meiotic DNA double-strand break (DSB) locations. We provide unprecedented support to the synthesis-dependent strand annealing model and establish estimates of its associated template switching frequency and polymerase processivity. We show that resolution of double Holliday junctions (dHJs) is biased toward cleavage of the pair of strands containing newly synthesized DNA near the junctions. The suspected dHJ resolvase Mlh1-3 as well as Mlh1-2, Exo1 and Sgs1 promote asymmetric positioning of crossover intermediates relative to the initiating DSB and bidirectional conversions. Finally, we show that crossover-biased dHJ resolution depends on Mlh1-3, Exo1, Msh5 and to a lesser extent on Sgs1. These properties are likely conserved in eukaryotes containing the ZMM proteins, which includes mammals.

genetics↗