Biology subjects

Lindblad-Toh, K.

Publications and source records attributed to Lindblad-Toh, K..

At least 19 recordsLinked to original sources

bioRxiv2026

Dog-human gene network colocalization links synaptic signalling and ubiquitination to compulsive disorders

Obsessive-compulsive disorder (OCD) is highly polygenic, and the largest genome-wide association study (GWAS), with 53,660 cases and 2,044,417 controls, identified only 30 loci, a small fraction of loci estimated to explain its heritability - too few to resolve biological pathways. Pet dogs develop a compulsive disorder (dogCD) similar to OCD. In a GWAS of dogCD with 2,584 dogs from the community science project Darwin's Ark, each dog locus explains at least 40-fold more phenotypic variance than each human OCD locus, giving power equivalent to the human GWAS with 80-fold fewer individuals. Combining the two GWAS identifies a 165-gene network undetectable in humans at current sample sizes. This network is enriched for genes expressed in neurons, particularly in the amygdala and cortex, and comprises four biological processes: excitatory-inhibitory synaptic transmission, axon guidance and neuron recognition, protein ubiquitination, and adenylyl cyclase-activating G-protein-coupled receptor signaling. Like most complex human traits, dogCD risk is likely driven by regulatory variation: fine-mapped dogCD SNPs are non-coding, and dogCD loci are enriched in candidate cis-regulatory elements (cCREs) in a new dog epigenomic atlas spanning eight brain regions. The cross-species network implicates an inherited risk architecture largely outside current OCD pharmacotherapy, and establishes pet dogs as a model for gene network discovery, particularly for conditions underpowered in human studies.

genetics↗

bioRxiv2026

A single nuclei expression resource for exploring dog brain cell transcriptomic diversity

Domesticated dogs present a unique case in nature where mutualism with and selective breeding by humans has led to profound changes in their environment, physiology, and behaviour compared to their wolf-like ancestors. Dog tameness, sociability, and trainability have likely evolved due to significant alterations to brain function. Exploring the effects of domestication on the dog brain will be facilitated by the characterisation of dog brain cell diversity, a task which is not yet complete. To fill this gap, we use single-nucleus RNA sequencing and survey cell types across the dog brain. We present transcriptomes from almost 60,000 cells sampled from the cerebellum, thalamus, and three regions of the cerebrum. Our analysis identified 24 major clusters representing 21 broad cell types, and 131 subclusters revealing regional variation. Comparisons with human and mouse datasets revealed a high level of conservation in neurons across mammalian brains, and greater divergence in glial cells, particularly oligodendrocytes. We demonstrate the utility of the dataset for interrogating specific gene expression patterns across the brain, including genes implicated in dog domestication, behavioural traits, and disease. We discover distinct differences in the expression of opioid receptors in the brains of dogs, compared to humans and mice, providing a potential explanation for dogs' higher tolerance and lower risk of severe adverse effects of opioid drugs. The data from this project are released via a web application for use by the wider community.

genomics↗

bioRxiv2024

The landscape of gene loss and missense variation across the mammalian tree informs on gene essentiality

BackgroundThe degree of gene and sequence preservation across species provides valuable insights into the relative necessity of genes from the perspective of natural selection. Here, we developed novel interspecies metrics across 462 mammalian species, GISMO (Gene identity score of mammalian orthologs) and GISMO-mis (GISMO-missense), to quantify gene loss traversing millions of years of evolution. GISMO is a measure of gene loss across mammals weighed by evolutionary distance relative to humans, whereas GISMO-mis quantifies the ratio of missense to synonymous variants across mammalian species for a given gene. RationaleDespite large sample sizes, current human constraint metrics are still not well calibrated for short genes. Traversing over 100 million years of evolution across hundreds of mammals can identify the most essential genes and improve gene-disease association. Beyond human genetics, these metrics provide measures of gene constraint to further enable mammalian genetics research. ResultsOur analyses showed that both metrics are strongly correlated with measures of human gene constraint for loss-of-function, missense, and copy number dosage derived from upwards of a million human samples, which highlight the power of interspecies constraint. Importantly, neither GISMO nor GISMO-mis are strongly correlated with coding sequence length. Therefore both metrics can identify novel constrained genes that were too small for existing human constraint metrics to capture. We also found that GISMO scores capture rare variant association signals across a range of phenotypes associated with decreased fecundity, such as schizophrenia, autism, and neurodevelopmental disorders. Moreover, common variant heritability of disease traits are highly enriched in the most constrained deciles of both metrics, further underscoring the biological relevance of these metrics in identifying functionally important genes. We further showed that both scores have the lowest duplication and deletion rate in the most constrained deciles for copy number variants in the UK Biobank, suggesting that it may be an important metric for dosage sensitivity. We additionally demonstrate that GISMO can improve prioritization of recessive disorder genes and captures homozygous selection. ConclusionsOverall, we demonstrate that the most constrained genes for gene loss and missense variation capture the largest fraction of heritability, GISMO can help prioritize recessive disorder genes, and identify the most conserved genes across the mammalian tree. O_FIG O_LINKSMALLFIG WIDTH=168 HEIGHT=200 SRC="FIGDIR/small/594531v1_ufig1.gif" ALT="Figure 1"> View larger version (79K): org.highwire.dtl.DTLVardef@11c3e46org.highwire.dtl.DTLVardef@13c6e70org.highwire.dtl.DTLVardef@76a6c7org.highwire.dtl.DTLVardef@1bf8d86_HPS_FORMAT_FIGEXP M_FIG C_FIG

genetics↗

bioRxiv2024

Interpreting mammalian evolutionary constraint at synonymous sites in light of the unwanted transcript hypothesis

The unwanted transcript hypothesis presents a potential explanation for cryptic evolutionary constraint at synonymous sites in species with low effective population sizes, such as humans and other mammals. Selection for higher GC content and against mutations that alter splicing in native transcripts is predicted to shape synonymous site content and protect against unwanted transcripts. Here, we interpret mammalian synonymous site constraint in this context. Utilising the largest alignment of 240 placental mammal genomes and single-base resolution constraint scores, we show that 20.8% of four-fold degenerate sites are under significant constraint across mammals. There is a strong bias for guanine (G) and cytosine (C) at constrained sites, marked constraint near splice sites, and variation in human populations shows a bias against mutations that reduce synonymous site GC content. We find evidence for higher constraint on four-fold degenerate sites in species with small historic effective population sizes and high young transposable element genome content. Genes enriched for synonymous site constraint, including those forming CpG sites, are tightly regulated and integral to organismal viability through their involvement in embryo development and transcriptional regulation.

evolutionary biology↗

bioRxiv2023

Chiropterans are a hotspot for horizontal transfer of DNA transposons in Mammalia

Horizontal transfer of transposable elements is an important mechanism contributing to genetic diversity and innovation. Bats (order Chiroptera) have repeatedly been shown to experience horizontal transfer of transposable elements at what appears to be a high rate compared to other mammals. We investigated the occurrence of horizontally transferred DNA transposons involving bats. We found over 200 putative horizontally transferred elements within bats; sixteen transposons were shared across distantly related mammalian clades and two other elements were shared with a fish and two lizard species. Our results indicate that bats are a hotspot for horizontal transfer of DNA transposons. These events broadly coincide with the diversification of several bat clades, supporting the hypothesis that DNA transposon invasions have contributed to genetic diversification of bats.

molecular biology↗

bioRxiv2023

Title: Leveraging Base Pair Mammalian Constraint to Understand Genetic Variation and Human Disease

Although thousands of genomic regions have been associated with heritable human diseases, attempts to elucidate biological mechanisms are impeded by a general inability to discern which genomic positions are functionally important. Evolutionary constraint is a powerful predictor of function that is agnostic to cell type or disease mechanism. Here, single base phyloP scores from the whole genome alignment of 240 placental mammals identified 3.5% of the human genome as significantly constrained, and likely functional. We compared these scores to large-scale genome annotation, genome-wide association studies (GWAS), copy number variation, clinical genetics findings, and cancer data sets. Evolutionarily constrained positions are enriched for variants explaining common disease heritability (more than any other functional annotation). Our results improve variant annotation but also highlight that the regulatory landscape of the human genome still needs to be further explored and linked to disease.

genomics↗

bioRxiv2022

Insights into mammalian TE diversity via the curation of 248 mammalian genome assemblies

We examined transposable element (TE) content of 248 placental mammal genome assemblies, the largest de novo TE curation effort in eukaryotes to date. We find that while mammals resemble one another in total TE content and diversity, they show substantial differences with regard to recent TE accumulation. This includes multiple recent expansion and quiescence events across the mammalian tree. Young TEs, particularly LINEs, drive increases in genome size while DNA transposons are associated with smaller genomes. Mammals tend to accumulate only a few types of TE at any given time, with one TE type dominating. We also found association between dietary habit and the presence of DNA transposon invasions. These detailed annotations will serve as a benchmark for future comparative TE analyses among placental mammals. One-Sentence SummaryA de novo assessment of TE content in 248 mammals finds informative trends in mammalian genome evolution.

genomics↗

bioRxiv2022

Using evolutionary constraint to define novel candidate driver genes in medulloblastoma

Current knowledge of cancer genomics is biased against non-coding mutations. Here, we use whole genome sequencing data from pediatric brain tumors, combined with evolutionary constraint inferred from 240 mammals to identify genes enriched in non-coding constraint mutations (NCCMs). We compare medulloblastoma (MB, malignant) to pilocytic astrocytoma (PA, benign) and find drastically different NCCM frequencies between the two. In PA, a high NCCM frequency only affects the BRAF locus, while in MB, >500 genes have high levels of NCCMs. Intriguingly, many genes are associated with different age of onset, such as HOXB1 in young patients and NUAK1 in adult patients. Our analysis points to different molecular pathways in different patient groups. These novel candidate driver genes may assist patient stratification in MB and may be useful for treatment options. One-Sentence SummaryNon-coding constraint mutations implicate novel candidate genes to stratify medulloblastoma by age and subgroups.

cancer biology↗

bioRxiv2022

Three-dimensional genome re-wiring in loci with Human Accelerated Regions

Human Accelerated Regions (HARs) are conserved genomic loci that evolved at an accelerated rate in the human lineage and may underlie human-specific traits. We generated HARs and chimpanzee accelerated regions with the largest alignment of mammalian genomes to date. To facilitate exploration of accelerated evolution in other lineages, we implemented an open-source Nextflow pipeline that runs on any computing platform. Combining deep-learning with chromatin capture experiments in human and chimpanzee neural progenitor cells, we discovered a significant enrichment of HARs in topologically associating domains (TADs) containing human-specific genomic variants that change three-dimensional (3D) genome organization. Differential gene expression between humans and chimpanzees at these loci in multiple cell types suggests rewiring of regulatory interactions between HARs and neurodevelopmental genes. Thus, comparative genomics together with models of 3D genome folding revealed enhancer hijacking as an explanation for the rapid evolution of HARs. One-Sentence SummaryHuman-specific changes to 3D genome organization may have contributed to rapid evolution of mammalian-conserved loci in the human genome.

evolutionary biology↗

bioRxiv2021

Canine oral melanoma genomic and transcriptomic study defines two molecular subgroups with different therapeutical targets

Mucosal melanoma (MM) is a rare and aggressive clinical cancer that occurs mostly in the head, neck, and anogenital regions. Despite recent advances in genetics and the development of revolutionary treatments, such as immunotherapy, the prognosis for MM remains poor. Canine MM shares several clinical, histological, and genetic features with its human counterpart, offering a relevant spontaneous and immunocompetent model to decipher the genetic bases and explore treatment options for human MM. We performed an integrative genomic and transcriptomic analysis of 32 canine MM samples, which allowed us to identify two molecular subgroups differing in microenvironment and structural variant (SV) content. The overexpression of genes related to the microenvironment and T-cell response was associated with tumors harboring a lower content of structural variants, whereas the overexpression of pigmentation-related pathways and oncogenes such as TERT were associated with a high SV burden. To detail the SVs, especially those with focal amplifications, whole-genome sequencing was performed on four canine MM cell lines. We showed that focal amplifications characterized complex chromosomal rearrangements targeting oncogenes such as MDM2 or CDK4 and a recurrently amplified region on canine chromosome 30, comprising the genes TRPM7, GABPB1, USP8, and SPPL2A, were candidate oncogenes for MM. We showed that the copy numbers of these genes were significantly correlated with their expression levels. Finally, we demonstrated that the genes TRPM7, GABPB1, and SPPL2A play a role in cell proliferation; thus, these may be considered new candidate oncogenes for human MM. Our findings suggest the existence of two MM molecular subgroups that may benefit from dedicated therapies, such as immune checkpoint inhibitors or targeted therapies. These results illustrate the relevance of dog models for deciphering genetic mechanisms in spontaneous MM, along with the potential to screen for efficient targeted therapies for rare and aggressive cancers in humans.

cancer biology↗

bioRxiv2021

Transcriptional and Functional Activity of Canine Hemangiosarcoma to Support Hematopoiesis Demonstrate Bone Marrow Nurse Cell Ontogeny

Hemangiosarcoma and angiosarcoma are soft-tissue sarcomas of blood vessel-forming cells in dogs and humans, respectively. These vasoformative sarcomas are aggressive and highly metastatic, with disorganized, irregular blood-filled vascular spaces. Our objective was to define molecular programs which support the niche that enables progression of canine hemangiosarcoma and human angiosarcoma. Dog-in-mouse hemangiosarcoma xenografts recapitulated the vasoformative and highly angiogenic morphology and molecular characteristics of primary tumors. Blood vessels in the tumors were complex and disorganized, and they were lined by both donor and host cells, a trait that was not observed in xenografts from canine osteosarcoma and lymphoma. In some cases, the xenografted hemangiosarcoma cells created exuberant myeloid hyperplasia and gave rise to lymphoproliferative tumors of mouse origin. We did not uncover a definitive transmissible etiology, but our functional analyses indicate that hemangiosarcoma cells generate a microenvironment that supports expansion and differentiation of hematopoietic progenitor populations. We conclude that canine hemangiosarcomas, and possibly human angiosarcomas, originate from stromal cells that are part of the bone marrow niche and that these cells may also support the growth of hematopoietic tumors. SignificanceWe demonstrate that molecular programs supporting expansion of immune and inflammatory cells in hemangiosarcoma resemble those of bone marrow niche cells, providing insights into the potential roles of these cells - whether physiological or pathological - in creating a permissive environment for the progression of hematopoietic malignancies.

cancer biology↗

bioRxiv2020

The meadow jumping mouse genome and transcriptome suggest mechanisms of hibernation

Hibernating mammals exhibit medically relevant phenotypes, but the genetic basis of hibernation remains poorly understood. Using the meadow jumping mouse (Zapus hudsonius), we investigated the genetic underpinnings of hibernation by uniting experimental and comparative genomic approaches. We assembled a Z. hudsonius genome and identified widespread expression changes during hibernation in genes important for circadian rhythm, membrane fluidity, and cell cycle arrest. Tissue-specific gene expression changes during torpor encompassed Wnt signaling in the brain and structural and transport functions in the kidney brush border. Using genomes from the closely related Zapus oregonus (previously classified as Z. princeps) and leveraging a panel of hibernating and non-hibernating rodents, we found selective pressure on genes involved in feeding behavior, metabolism, and cell biological processes potentially important for function at low body temperature. Leptin stands out with elevated conservation in hibernating rodents, implying a role for this metabolic hormone in triggering fattening and hibernation. These findings illustrate that mammalian hibernation requires adaptation at all levels of organismal form and function and lay the groundwork for future study of hibernation phenotypes.

genomics↗

bioRxiv2020

Genomically Complex Human Angiosarcoma and Canine Hemangiosarcoma Establish Convergent Angiogenic Transcriptional Programs

Sporadic angiosarcomas (ASs) are aggressive vascular sarcomas whose rarity and genomic complexity present significant obstacles in deciphering the pathogenic significance of individual genetic alterations. Numerous fusion genes have been identified across multiple types of cancers, but their existence and significance remain unclear in sporadic ASs. In this study, we leveraged RNA sequencing data from thirteen human ASs and 76 spontaneous canine hemangiosarcomas (HSAs) to identify fusion genes associated with spontaneous vascular malignancies. Ten novel protein-coding fusion genes, including TEX2-PECAM1 and ATP8A2-FLT1, were identified in seven of the thirteen human tumors, with two tumors showing mutations of TP53. HRAS and NRAS mutations were found in ASs without fusions or TP53 mutations. We found fifteen novel protein-coding fusion genes including MYO16-PTK2, GABRA3-FLT1, and AKT3-XPNPEP1 in eleven of the 76 canine HSAs; these fusion genes were seen exclusively in tumors of the angiogenic molecular subtype that contained recurrent mutations in TP53, PIK3CA, PIK3R1, and NRAS. In particular, fusion genes and mutations of TP53 co-occurred in tumors with higher frequency than expected by random chance, and they enriched gene signatures predicting activation of angiogenic pathways. Comparative transcriptomic analysis of human ASs and canine HSAs identified shared molecular signatures associated with activation of PI3K/AKT/mTOR pathways. Our data show that, while driver events of malignant vasoformative tumors of humans and dogs include diverse mutations and stochastic rearrangements that create novel fusion genes, convergent transcriptional programs govern the highly conserved morphological organization and biological behavior of these tumors in both species.

cancer biology↗

bioRxiv2020

A new long-read dog assembly uncovers thousands of exons and functional elements missing in the previous reference

Here we present a new high-quality canine reference genome with gap number reduced 41-fold, from 23,836 to 585. Analysis of existing and novel data, RNA-seq, miRNA-seq and ATAC-seq, revealed a large proportion of these harboured previously hidden elements, including genes, promoters and miRNAs. Short-read dark regions were detected, and genomic regions completed, including the DLA, TCR and 366 cancer genes. 10x sequencing of 27 dogs uncovered a total of 22.1 million SNPs, Indels and larger structural variants (SVs). 1.4% overlap with protein coding genes and could provide a source of normal or aberrant phenotypic modifications.

genomics↗

bioRxiv2020

Broad Host Range of SARS-CoV-2 Predicted by Comparative and Structural Analysis of ACE2 in Vertebrates

The novel coronavirus SARS-CoV-2 is the cause of Coronavirus Disease-2019 (COVID-19). The main receptor of SARS-CoV-2, angiotensin I converting enzyme 2 (ACE2), is now undergoing extensive scrutiny to understand the routes of transmission and sensitivity in different species. Here, we utilized a unique dataset of 410 vertebrates, including 252 mammals, to study cross-species conservation of ACE2 and its likelihood to function as a SARS-CoV-2 receptor. We designed a five-category ranking score based on the conservation properties of 25 amino acids important for the binding between receptor and virus, classifying all species from very high to very low. Only mammals fell into the medium to very high categories, and only catarrhine primates in the very high category, suggesting that they are at high risk for SARS-CoV-2 infection. We employed a protein structural analysis to qualitatively assess whether amino acid changes at variable residues would be likely to disrupt ACE2/SARS-CoV-2 binding, and found the number of predicted unfavorable changes significantly correlated with the binding score. Extending this analysis to human population data, we found only rare (<0.1%) variants in 10/25 binding sites. In addition, we observed evidence of positive selection in ACE2 in multiple species, including bats. Utilized appropriately, our results may lead to the identification of intermediate host species for SARS-CoV-2, justify the selection of animal models of COVID-19, and assist the conservation of animals both in native habitats and in human care.

genomics↗

bioRxiv2019

Progressive alignment with Cactus: a multiple-genome aligner for the thousand-genome era

Cactus, a reference-free multiple genome alignment program, has been shown to be highly accurate, but the existing implementation scales poorly with increasing numbers of genomes, and struggles in regions of highly duplicated sequence. We describe progressive extensions to Cactus that enable reference-free alignment of tens to thousands of large vertebrate genomes while maintaining high alignment quality. We show that Cactus is capable of scaling to hundreds of genomes and beyond by describing results from an alignment of over 600 amniote genomes, which is to our knowledge the largest multiple vertebrate genome alignment yet created. Further, we show improvements in orthology resolution leading to downstream improvements in annotation.

genomics↗

bioRxiv2019

SweHLA: the high confidence HLA typing bio-resource drawn from 1 000 Swedish genomes

There is a need to accurately call human leukocyte antigen (HLA) genes from existing short-read sequencing data, however there is no single solution that matches the gold standard of lab typing. Here we aimed to combine results from available software, minimising the biases of applied algorithm and HLA reference. The result is a robust HLA population resource for the published 1 000 Swedish genomes, and a framework for future HLA interrogation. HLA 2-field alleles were called using four imputation and inference methods for the classical eight genes (class I: HLA-A, -B, -C; class II: HLA-DPA1, -DPB1, -DQA1, -DQB1, -DRB1). A high confidence population set (SweHLA) was determined using an n-1 concordance rule for class I (four software) and class II (three software) alleles. Results were compared across populations and individual programs benchmarked to SweHLA. Per allele, 875 to 988 of the 1 000 samples were genotyped in SweHLA; 920 samples had at least seven loci. While a small fraction of reference alleles were common to all software (class I=1.9% and class II=4.1%), this did not affect the overall call rate. Gene-level concordance was high compared to European populations (>0.83%), with COX and PGF the dominant SweHLA haplotypes. We noted that 15/18 discordant alleles (delta allele frequency > 2) were previously reported as disease-associated. These differences could in part explain across-study genetic replication failures, reinforcing the need to use multiple software. SweHLA demonstrates a way to use existing NGS data to generate a population resource agnostic to individual HLA software biases.

genetics↗

bioRxiv2019

Genomic analysis reveals shared genes and pathways in human and canine angiosarcoma

Angiosarcoma is a highly aggressive cancer of blood vessel-forming cells with high fatality and few effective treatment options. It is both rare and heterogenous, making large, well powered genomic studies nearly impossible. In dogs, angiosarcoma is common, with breeds like the golden retriever carrying heritable genetic factors that put them at very high risk. If the clinical similarity of canine and human angiosarcoma reflects shared genomic etiology, dogs could be a critically needed model for advancing angiosarcoma research. We assessed the genomic landscape of canine angiosarcoma via whole exome sequencing (47 golden retriever angiosarcomas) and RNA sequencing (74 angiosarcomas from multiple breeds). The predominant mutational signature was the age-associated deamination of cytosine to thymine, and somatic coding mutations occurred most frequently in the tumor suppressor TP53 (59.6% of cases) as well as two genes in the PI3K pathway: the oncogene PIK3CA (29.8%) and its regulatory subunit PIK3R1 (8.5%). We compared the canine data to human data recently released by The Angiosarcoma Project, and found the same genes and many of the same pathways significantly enriched for somatic mutations, most notably protein kinases, glycoproteins, fibronectin Type III domains, EGF-like domains, and cell adhesion proteins such as cadherins. As in human angiosarcoma, CDKN2A/B was recurrently deleted and VEGFA, KDR, and KIT recurrently gained. Canine angiosarcoma closely models human angiosarcoma on a genomic level, and is a powerful tool for investigating the pathogenesis of this devastating disease.

genomics↗