RESUMO
While ultraviolet (UV) radiation damages DNA, eliciting the DNA damage response (DDR), it also damages RNA, triggering transcriptome-wide ribosomal collisions and eliciting a ribotoxic stress response (RSR). However, the relative contributions, timing, and regulation of these pathways in determining cell fate is unclear. Here we use time-resolved phosphoproteomic, chemical-genetic, single-cell imaging, and biochemical approaches to create a chronological atlas of signaling events activated in cells responding to UV damage. We discover that UV-induced apoptosis is mediated by the RSR kinase ZAK and not through the DDR. We identify two negative-feedback modules that regulate ZAK-mediated apoptosis: (1) GCN2 activation limits ribosomal collisions and attenuates ZAK-mediated RSR and (2) ZAK activity leads to phosphodegron autophosphorylation and its subsequent degradation. These events tune ZAK's activity to collision levels to establish regimes of homeostasis, tolerance, and death, revealing its key role as the cellular sentinel for nucleic acid damage.
Assuntos
Apoptose , Dano ao DNA , Raios Ultravioleta , Raios Ultravioleta/efeitos adversos , Apoptose/efeitos da radiação , Fosforilação/efeitos da radiação , Humanos , Transdução de Sinais/efeitos da radiação , Proteínas Serina-Treonina Quinases/metabolismo , Estresse Fisiológico/efeitos da radiação , Ribossomos/metabolismo , Morte Celular/efeitos da radiaçãoRESUMO
Ultraviolet (UV) light and incompletely understood genetic and epigenetic variations determine skin color. Here we describe an UV- and microphthalmia-associated transcription factor (MITF)-independent mechanism of skin pigmentation. Targeting the mitochondrial redox-regulating enzyme nicotinamide nucleotide transhydrogenase (NNT) resulted in cellular redox changes that affect tyrosinase degradation. These changes regulate melanosome maturation and, consequently, eumelanin levels and pigmentation. Topical application of small-molecule inhibitors yielded skin darkening in human skin, and mice with decreased NNT function displayed increased pigmentation. Additionally, genetic modification of NNT in zebrafish alters melanocytic pigmentation. Analysis of four diverse human cohorts revealed significant associations of skin color, tanning, and sun protection use with various single-nucleotide polymorphisms within NNT. NNT levels were independent of UVB irradiation and redox modulation. Individuals with postinflammatory hyperpigmentation or lentigines displayed decreased skin NNT levels, suggesting an NNT-driven, redox-dependent pigmentation mechanism that can be targeted with NNT-modifying topical drugs for medical and cosmetic purposes.
Assuntos
Fator de Transcrição Associado à Microftalmia/metabolismo , NADP Trans-Hidrogenases/metabolismo , Pigmentação da Pele/efeitos da radiação , Raios Ultravioleta , Animais , Linhagem Celular , Estudos de Coortes , AMP Cíclico/metabolismo , Dano ao DNA , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Predisposição Genética para Doença , Humanos , Melanócitos/efeitos dos fármacos , Melanócitos/metabolismo , Melanossomas/efeitos dos fármacos , Melanossomas/metabolismo , Melanossomas/efeitos da radiação , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Monofenol Mono-Oxigenase/genética , Monofenol Mono-Oxigenase/metabolismo , NADP Trans-Hidrogenases/antagonistas & inibidores , Oxirredução/efeitos dos fármacos , Oxirredução/efeitos da radiação , Polimorfismo de Nucleotídeo Único/genética , Complexo de Endopeptidases do Proteassoma/metabolismo , Proteólise/efeitos dos fármacos , Proteólise/efeitos da radiação , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Pigmentação da Pele/efeitos dos fármacos , Pigmentação da Pele/genética , Ubiquitina/metabolismo , Peixe-ZebraRESUMO
In response to transcription-blocking DNA damage, cells orchestrate a multi-pronged reaction, involving transcription-coupled DNA repair, degradation of RNA polymerase II (RNAPII), and genome-wide transcription shutdown. Here, we provide insight into how these responses are connected by the finding that ubiquitylation of RNAPII itself, at a single lysine (RPB1 K1268), is the focal point for DNA-damage-response coordination. K1268 ubiquitylation affects DNA repair and signals RNAPII degradation, essential for surviving genotoxic insult. RNAPII degradation results in a shutdown of transcriptional initiation, in the absence of which cells display dramatic transcriptome alterations. Additionally, regulation of RNAPII stability is central to transcription recovery-persistent RNAPII depletion underlies the failure of this process in Cockayne syndrome B cells. These data expose regulation of global RNAPII levels as integral to the cellular DNA-damage response and open the intriguing possibility that RNAPII pool size generally affects cell-specific transcription programs in genome instability disorders and even normal cells.
Assuntos
Dano ao DNA , RNA Polimerase II/metabolismo , Reparo do DNA , Células HEK293 , Humanos , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Transcrição Gênica , Ubiquitinação , Raios UltravioletaRESUMO
Problems arising during translation of mRNAs lead to ribosome stalling and collisions that trigger a series of quality control events. However, the global cellular response to ribosome collisions has not been explored. Here, we uncover a function for ribosome collisions in signal transduction. Using translation elongation inhibitors and general cellular stress conditions, including amino acid starvation and UV irradiation, we show that ribosome collisions activate the stress-activated protein kinase (SAPK) and GCN2-mediated stress response pathways. We show that the MAPKKK ZAK functions as the sentinel for ribosome collisions and is required for immediate early activation of both SAPK (p38/JNK) and GCN2 signaling pathways. Selective ribosome profiling and biochemistry demonstrate that although ZAK generally associates with elongating ribosomes on polysomal mRNAs, it specifically auto-phosphorylates on the minimal unit of colliding ribosomes, the disome. Together, these results provide molecular insights into how perturbation of translational homeostasis regulates cell fate.
Assuntos
Ribossomos/metabolismo , Estresse Fisiológico , Transportadores de Cassetes de Ligação de ATP/metabolismo , Anisomicina/farmacologia , Apoptose/efeitos dos fármacos , Dano ao DNA/efeitos da radiação , Ativação Enzimática , Humanos , MAP Quinase Quinase Quinases/deficiência , MAP Quinase Quinase Quinases/genética , MAP Quinase Quinase Quinases/metabolismo , Proteína Quinase 14 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 14 Ativada por Mitógeno/metabolismo , Fosforilação , Polirribossomos/metabolismo , Isoformas de Proteínas/deficiência , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Interferência de RNA , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/metabolismo , Transdução de Sinais , Raios Ultravioleta , eIF-2 Quinase/metabolismoRESUMO
Error-prone polymerases are alleged to induce mutations while replicating damaged DNA and to increase the risk of cancer. Using in vitro studies and mice models, Yoon et al. (2019) provide evidence that the error-prone Pol θ polymerase protects against ultraviolet light-induced skin cancer despite its mutagenic potential.
Assuntos
Neoplasias Cutâneas , Raios Ultravioleta , Animais , DNA Polimerase Dirigida por DNA/genética , Camundongos , Mutagênese , DNA Polimerase tetaRESUMO
Cancers from sun-exposed skin accumulate "driver" mutations, causally implicated in oncogenesis. Because errors incorporated during translesion synthesis (TLS) opposite UV lesions would generate these mutations, TLS mechanisms are presumed to underlie cancer development. To address the role of TLS in skin cancer formation, we determined which DNA polymerase is responsible for generating UV mutations, analyzed the relative contributions of error-free TLS by Polη and error-prone TLS by Polθ to the replication of UV-damaged DNA and to genome stability, and examined the incidence of UV-induced skin cancers in Polθ-/-, Polη-/-, and Polθ-/- Polη-/- mice. Our findings that the incidence of skin cancers rises in Polθ-/- mice and is further exacerbated in Polθ-/- Polη-/- mice compared with Polη-/- mice support the conclusion that error-prone TLS by Polθ provides a safeguard against tumorigenesis and suggest that cancer formation can ensue in the absence of somatic point mutations.
Assuntos
DNA Polimerase Dirigida por DNA/metabolismo , DNA Polimerase Dirigida por DNA/fisiologia , Neoplasias Cutâneas/metabolismo , Animais , Dano ao DNA/genética , Reparo do DNA/genética , Replicação do DNA/fisiologia , Fibroblastos/metabolismo , Fibroblastos/efeitos da radiação , Instabilidade Genômica/genética , Humanos , Camundongos , Camundongos Knockout , Mutação/genética , Pele/citologia , Pele/metabolismo , Neoplasias Cutâneas/genética , Raios Ultravioleta/efeitos adversos , DNA Polimerase tetaRESUMO
Although clonal neo-antigen burden is associated with improved response to immune therapy, the functional basis for this remains unclear. Here we study this question in a novel controlled mouse melanoma model that enables us to explore the effects of intra-tumor heterogeneity (ITH) on tumor aggressiveness and immunity independent of tumor mutational burden. Induction of UVB-derived mutations yields highly aggressive tumors with decreased anti-tumor activity. However, single-cell-derived tumors with reduced ITH are swiftly rejected. Their rejection is accompanied by increased T cell reactivity and a less suppressive microenvironment. Using phylogenetic analyses and mixing experiments of single-cell clones, we dissect two characteristics of ITH: the number of clones forming the tumor and their clonal diversity. Our analysis of melanoma patient tumor data recapitulates our results in terms of overall survival and response to immune checkpoint therapy. These findings highlight the importance of clonal mutations in robust immune surveillance and the need to quantify patient ITH to determine the response to checkpoint blockade.
Assuntos
Heterogeneidade Genética/efeitos da radiação , Melanoma/genética , Melanoma/imunologia , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/imunologia , Raios Ultravioleta/efeitos adversos , Animais , Carcinogênese/genética , Linhagem Celular Tumoral , Estudos de Coortes , Modelos Animais de Doenças , Feminino , Humanos , Linfócitos do Interstício Tumoral , Melanoma/mortalidade , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Camundongos Knockout , Mutação/efeitos da radiação , Filogenia , Neoplasias Cutâneas/mortalidade , Taxa de Sobrevida , Linfócitos T/imunologia , Microambiente Tumoral/imunologia , Microambiente Tumoral/efeitos da radiaçãoRESUMO
DNA repair has been hypothesized to be a longevity determinant, but the evidence for it is based largely on accelerated aging phenotypes of DNA repair mutants. Here, using a panel of 18 rodent species with diverse lifespans, we show that more robust DNA double-strand break (DSB) repair, but not nucleotide excision repair (NER), coevolves with longevity. Evolution of NER, unlike DSB, is shaped primarily by sunlight exposure. We further show that the capacity of the SIRT6 protein to promote DSB repair accounts for a major part of the variation in DSB repair efficacy between short- and long-lived species. We dissected the molecular differences between a weak (mouse) and a strong (beaver) SIRT6 protein and identified five amino acid residues that are fully responsible for their differential activities. Our findings demonstrate that DSB repair and SIRT6 have been optimized during the evolution of longevity, which provides new targets for anti-aging interventions.
Assuntos
Quebras de DNA de Cadeia Dupla , Reparo do DNA , Longevidade/genética , Sirtuínas/metabolismo , Sequência de Aminoácidos , Animais , Peso Corporal , Quebras de DNA de Cadeia Dupla/efeitos da radiação , Evolução Molecular , Fibroblastos/citologia , Fibroblastos/metabolismo , Técnicas de Inativação de Genes , Humanos , Cinética , Masculino , Mutagênese , Filogenia , Roedores/classificação , Alinhamento de Sequência , Sirtuínas/química , Sirtuínas/genética , Raios UltravioletaRESUMO
Sunlight exposure is known to affect mood, learning, and cognition. However, the molecular and cellular mechanisms remain elusive. Here, we show that moderate UV exposure elevated blood urocanic acid (UCA), which then crossed the blood-brain barrier. Single-cell mass spectrometry and isotopic labeling revealed a novel intra-neuronal metabolic pathway converting UCA to glutamate (GLU) after UV exposure. This UV-triggered GLU synthesis promoted its packaging into synaptic vesicles and its release at glutamatergic terminals in the motor cortex and hippocampus. Related behaviors, like rotarod learning and object recognition memory, were enhanced after UV exposure. All UV-induced metabolic, electrophysiological, and behavioral effects could be reproduced by the intravenous injection of UCA and diminished by the application of inhibitor or short hairpin RNA (shRNA) against urocanase, an enzyme critical for the conversion of UCA to GLU. These findings reveal a new GLU biosynthetic pathway, which could contribute to some of the sunlight-induced neurobehavioral changes.
Assuntos
Encéfalo/efeitos da radiação , Ácido Glutâmico/biossíntese , Aprendizagem/efeitos da radiação , Memória/efeitos da radiação , Raios Ultravioleta , Animais , Encéfalo/metabolismo , Encéfalo/patologia , Cromatografia Líquida de Alta Pressão , Imageamento por Ressonância Magnética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/citologia , Neurônios/fisiologia , Técnicas de Patch-Clamp , Interferência de RNA , RNA Interferente Pequeno/metabolismo , Espectrometria de Massas em Tandem , Urocanato Hidratase/antagonistas & inibidores , Urocanato Hidratase/genética , Urocanato Hidratase/metabolismo , Ácido Urocânico/sangue , Ácido Urocânico/metabolismoRESUMO
Exposure to ultraviolet light leads to a cell-wide DNA damage response that includes a global reduction in transcription. Williamson et al., identify a protein involved in this process as well as a noncoding RNA produced by alternative processing of RNA transcribed from the same gene that promotes recovery from the repressed state.
Assuntos
RNA , Transcrição Gênica , Dano ao DNA , RNA não Traduzido/genética , Raios UltravioletaRESUMO
Many processes can cause the same nucleotide change in a genome, making the identification of the mechanisms causing mutations a difficult challenge. Here, we show that clustered mutations provide a more precise fingerprint of mutagenic processes. Of nine clustered mutation signatures identified from >1,000 tumor genomes, three relate to variable APOBEC activity and three are associated with tobacco smoking. An additional signature matches the spectrum of translesion DNA polymerase eta (POLH). In lymphoid cells, these mutations target promoters, consistent with AID-initiated somatic hypermutation. In solid tumors, however, they are associated with UV exposure and alcohol consumption and target the H3K36me3 chromatin of active genes in a mismatch repair (MMR)-dependent manner. These regions normally have a low mutation rate because error-free MMR also targets H3K36me3 chromatin. Carcinogens and error-prone repair therefore redistribute mutations to the more important regions of the genome, contributing a substantial mutation load in many tumors, including driver mutations.
Assuntos
Reparo de Erro de Pareamento de DNA , Mutação , Neoplasias/genética , Desaminases APOBEC , Citidina Desaminase , Citosina Desaminase/genética , DNA Polimerase Dirigida por DNA/genética , Humanos , Neoplasias Hepáticas/induzido quimicamente , Neoplasias Hepáticas/genética , Melanoma/genética , Mutagênese , Fumar/efeitos adversos , Raios Ultravioleta/efeitos adversosRESUMO
The transcription-related DNA damage response was analyzed on a genome-wide scale with great spatial and temporal resolution. Upon UV irradiation, a slowdown of transcript elongation and restriction of gene activity to the promoter-proximal â¼25 kb is observed. This is associated with a shift from expression of long mRNAs to shorter isoforms, incorporating alternative last exons (ALEs) that are more proximal to the transcription start site. Notably, this includes a shift from a protein-coding ASCC3 mRNA to a shorter ALE isoform of which the RNA, rather than an encoded protein, is critical for the eventual recovery of transcription. The non-coding ASCC3 isoform counteracts the function of the protein-coding isoform, indicating crosstalk between them. Thus, the ASCC3 gene expresses both coding and non-coding transcript isoforms with opposite effects on transcription recovery after UV-induced DNA damage.
Assuntos
Processamento Alternativo/efeitos da radiação , DNA Helicases/genética , RNA não Traduzido/genética , Transcrição Gênica , Raios Ultravioleta , Linhagem Celular , Éxons , Humanos , RNA Polimerase II/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Elongação da Transcrição Genética/efeitos da radiação , Iniciação da Transcrição Genética/efeitos da radiaçãoRESUMO
Many animal tissues/cells are photosensitive, yet only two types of photoreceptors (i.e., opsins and cryptochromes) have been discovered in metazoans. The question arises as to whether unknown types of photoreceptors exist in the animal kingdom. LITE-1, a seven-transmembrane gustatory receptor (GR) homolog, mediates UV-light-induced avoidance behavior in C. elegans. However, it is not known whether LITE-1 functions as a chemoreceptor or photoreceptor. Here, we show that LITE-1 directly absorbs both UVA and UVB light with an extinction coefficient 10-100 times that of opsins and cryptochromes, indicating that LITE-1 is highly efficient in capturing photons. Unlike typical photoreceptors employing a prosthetic chromophore to capture photons, LITE-1 strictly depends on its protein conformation for photon absorption. We have further identified two tryptophan residues critical for LITE-1 function. Interestingly, unlike GPCRs, LITE-1 adopts a reversed membrane topology. Thus, LITE-1, a taste receptor homolog, represents a distinct type of photoreceptor in the animal kingdom.
Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/metabolismo , Proteínas de Membrana/metabolismo , Animais , Caenorhabditis elegans/efeitos da radiação , Proteínas de Caenorhabditis elegans/química , Proteínas de Caenorhabditis elegans/isolamento & purificação , Proteínas de Membrana/química , Proteínas de Membrana/isolamento & purificação , Fótons , Conformação Proteica , Triptofano/metabolismo , Raios UltravioletaRESUMO
UV irradiation induces "bulky" DNA photodimers such as (6-4)-photoproducts and cyclobutane pyrimidine dimers that are removed by nucleotide excision repair, a complex process defective in the sunlight-sensitive and cancer-prone disease xeroderma pigmentosum. Some bacteria and lower eukaryotes can also repair photodimers by enzymatically simpler mechanisms, but such pathways have not been reported in normal human cells. Here, we have identified such a mechanism. We show that normal human cells can employ a DNA base excision repair process involving NTH1, APE1, PARP1, XRCC1, and FEN1 to rapidly remove a subset of photodimers at early times following UVC irradiation. Loss of these proteins slows the early rate of repair of photodimers in normal cells, ablates their residual repair in xeroderma pigmentosum cells, and increases UVC sensitivity â¼2-fold. These data reveal that human cells can excise photodimers using a long-patch base excision repair process that functions additively but independently of nucleotide excision repair.
Assuntos
Xeroderma Pigmentoso , Humanos , Xeroderma Pigmentoso/genética , Reparo do DNA/genética , Dímeros de Pirimidina/genética , Dímeros de Pirimidina/metabolismo , Dano ao DNA/genética , DNA/genética , Raios Ultravioleta , Proteína 1 Complementadora Cruzada de Reparo de Raio-X/metabolismoRESUMO
Solar ultraviolet-B (UV-B) radiation has played a crucial role in the evolution of life on Earth, and potential changes in its levels could affect the health and functionality of humans and the ecosystems. UV exposure presents both risks and benefits to humans. However, optimal UV-B radiation exposure depends on several environmental and physiological factors and cannot be easily determined. The present document provides a review of the current state of knowledge relative to the effects of UV-B radiation on human health. A brief description of the physical mechanisms that control the levels of solar UV-B radiation at the Earth's surface is provided, with special emphasis on the role of ozone and the importance of the Montreal Protocol. A comprehensive review of studies reporting current trends in levels of surface solar UV-B radiation and projections of future levels reveals the dominant role of climatic changes in the long-term variability of UV-B radiation and its impact on the development of melanomas as well as eye disorders. The review provides strong evidence that despite the success of the Montreal Protocol and the expected ozone recovery, the future evolution of the levels of solar UV-B radiation at the Earth's surface is not certain.
Assuntos
Ecossistema , Ozônio , Humanos , Raios Ultravioleta/efeitos adversos , Doses de RadiaçãoRESUMO
DNA base damage is a major source of oncogenic mutations1. Such damage can produce strand-phased mutation patterns and multiallelic variation through the process of lesion segregation2. Here we exploited these properties to reveal how strand-asymmetric processes, such as replication and transcription, shape DNA damage and repair. Despite distinct mechanisms of leading and lagging strand replication3,4, we observe identical fidelity and damage tolerance for both strands. For small alkylation adducts of DNA, our results support a model in which the same translesion polymerase is recruited on-the-fly to both replication strands, starkly contrasting the strand asymmetric tolerance of bulky UV-induced adducts5. The accumulation of multiple distinct mutations at the site of persistent lesions provides the means to quantify the relative efficiency of repair processes genome wide and at single-base resolution. At multiple scales, we show DNA damage-induced mutations are largely shaped by the influence of DNA accessibility on repair efficiency, rather than gradients of DNA damage. Finally, we reveal specific genomic conditions that can actively drive oncogenic mutagenesis by corrupting the fidelity of nucleotide excision repair. These results provide insight into how strand-asymmetric mechanisms underlie the formation, tolerance and repair of DNA damage, thereby shaping cancer genome evolution.
Assuntos
Dano ao DNA , Reparo do DNA , DNA Polimerase Dirigida por DNA , DNA , Mutagênese , Mutação , Animais , Humanos , Camundongos , Alquilação/efeitos da radiação , Linhagem Celular , DNA/química , DNA/genética , DNA/metabolismo , DNA/efeitos da radiação , Adutos de DNA/química , Adutos de DNA/genética , Adutos de DNA/metabolismo , Adutos de DNA/efeitos da radiação , Dano ao DNA/genética , Dano ao DNA/efeitos da radiação , Reparo do DNA/genética , Reparo do DNA/fisiologia , Replicação do DNA , DNA Polimerase Dirigida por DNA/metabolismo , Mutagênese/genética , Mutagênese/efeitos da radiação , Mutação/genética , Mutação/efeitos da radiação , Neoplasias/genética , Transcrição Gênica , Raios Ultravioleta/efeitos adversosRESUMO
UV light is an established carcinogen, yet evidence suggests that UV-seeking behavior has addictive features. Following UV exposure, epidermal keratinocytes synthesize proopiomelanocortin (POMC) that is processed to melanocyte-stimulating hormone, inducing tanning. We show that, in rodents, another POMC-derived peptide, ß-endorphin, is coordinately synthesized in skin, elevating plasma levels after low-dose UV. Increases in pain-related thresholds are observed and reversed by pharmacologic opioid antagonism. Opioid blockade also elicits withdrawal signs after chronic UV exposure. This effect was sufficient to guide operant behavioral choices to avoidance of opioid withdrawal (conditioned place aversion). These UV-induced nociceptive and behavioral effects were absent in ß-endorphin knockout mice and in mice lacking p53-mediated POMC induction in epidermal keratinocytes. Although primordial UV addiction, mediated by the hedonic action of ß-endorphin and anhedonic effects of withdrawal, may theoretically have enhanced evolutionary vitamin D biosynthesis, it now may contribute to the relentless rise in skin cancer incidence in humans.
Assuntos
Comportamento Aditivo , Pele/efeitos da radiação , beta-Endorfina/metabolismo , Animais , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Modelos Animais , Pele/metabolismo , Raios Ultravioleta , beta-Endorfina/genéticaRESUMO
Human genomics is witnessing an ongoing paradigm shift from a single reference sequence to a pangenome form, but populations of Asian ancestry are underrepresented. Here we present data from the first phase of the Chinese Pangenome Consortium, including a collection of 116 high-quality and haplotype-phased de novo assemblies based on 58 core samples representing 36 minority Chinese ethnic groups. With an average 30.65× high-fidelity long-read sequence coverage, an average contiguity N50 of more than 35.63 megabases and an average total size of 3.01 gigabases, the CPC core assemblies add 189 million base pairs of euchromatic polymorphic sequences and 1,367 protein-coding gene duplications to GRCh38. We identified 15.9 million small variants and 78,072 structural variants, of which 5.9 million small variants and 34,223 structural variants were not reported in a recently released pangenome reference1. The Chinese Pangenome Consortium data demonstrate a remarkable increase in the discovery of novel and missing sequences when individuals are included from underrepresented minority ethnic groups. The missing reference sequences were enriched with archaic-derived alleles and genes that confer essential functions related to keratinization, response to ultraviolet radiation, DNA repair, immunological responses and lifespan, implying great potential for shedding new light on human evolution and recovering missing heritability in complex disease mapping.
Assuntos
População do Leste Asiático , Etnicidade , Variação Genética , Genoma Humano , Genética Humana , Grupos Minoritários , Humanos , População do Leste Asiático/classificação , População do Leste Asiático/genética , Etnicidade/genética , Genoma Humano/genética , Análise de Sequência de DNA , Raios Ultravioleta , Genética Humana/normas , Minorias Étnicas e Raciais , Padrões de Referência , Haplótipos/genética , Eucromatina/genética , Alelos , Reparo do DNA/genética , Queratinas/genética , Queratinas/metabolismo , Longevidade/genética , Imunidade/genéticaRESUMO
The skin epidermis is constantly renewed throughout life1,2. Disruption of the balance between renewal and differentiation can lead to uncontrolled growth and tumour initiation3. However, the ways in which oncogenic mutations affect the balance between renewal and differentiation and lead to clonal expansion, cell competition, tissue colonization and tumour development are unknown. Here, through multidisciplinary approaches that combine in vivo clonal analysis using intravital microscopy, single-cell analysis and functional analysis, we show how SmoM2-a constitutively active oncogenic mutant version of Smoothened (SMO) that induces the development of basal cell carcinoma-affects clonal competition and tumour initiation in real time. We found that expressing SmoM2 in the ear epidermis of mice induced clonal expansion together with tumour initiation and invasion. By contrast, expressing SmoM2 in the back-skin epidermis led to a clonal expansion that induced lateral cell competition without dermal invasion and tumour formation. Single-cell analysis showed that oncogene expression was associated with a cellular reprogramming of adult interfollicular cells into an embryonic hair follicle progenitor (EHFP) state in the ear but not in the back skin. Comparisons between the ear and the back skin revealed that the dermis has a very different composition in these two skin types, with increased stiffness and a denser collagen I network in the back skin. Decreasing the expression of collagen I in the back skin through treatment with collagenase, chronic UV exposure or natural ageing overcame the natural resistance of back-skin basal cells to undergoing EHFP reprogramming and tumour initiation after SmoM2 expression. Altogether, our study shows that the composition of the extracellular matrix regulates how susceptible different regions of the body are to tumour initiation and invasion.
Assuntos
Transformação Celular Neoplásica , Matriz Extracelular , Neoplasias Cutâneas , Microambiente Tumoral , Animais , Camundongos , Transformação Celular Neoplásica/metabolismo , Transformação Celular Neoplásica/patologia , Colágeno/metabolismo , Epiderme/patologia , Matriz Extracelular/metabolismo , Matriz Extracelular/patologia , Neoplasias Cutâneas/patologia , Carcinoma Basocelular/patologia , Orelha/patologia , Colagenases/metabolismo , Envelhecimento , Raios Ultravioleta , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismoRESUMO
Tumours most often arise from progression of precursor clones within a single anatomical niche. In the bone marrow, clonal progenitors can undergo malignant transformation to acute leukaemia, or differentiate into immune cells that contribute to disease pathology in peripheral tissues1-4. Outside the marrow, these clones are potentially exposed to a variety of tissue-specific mutational processes, although the consequences of this are unclear. Here we investigate the development of blastic plasmacytoid dendritic cell neoplasm (BPDCN)-an unusual form of acute leukaemia that often presents with malignant cells isolated to the skin5. Using tumour phylogenomics and single-cell transcriptomics with genotyping, we find that BPDCN arises from clonal (premalignant) haematopoietic precursors in the bone marrow. We observe that BPDCN skin tumours first develop at sun-exposed anatomical sites and are distinguished by clonally expanded mutations induced by ultraviolet (UV) radiation. A reconstruction of tumour phylogenies reveals that UV damage can precede the acquisition of alterations associated with malignant transformation, implicating sun exposure of plasmacytoid dendritic cells or committed precursors during BPDCN pathogenesis. Functionally, we find that loss-of-function mutations in Tet2, the most common premalignant alteration in BPDCN, confer resistance to UV-induced cell death in plasmacytoid, but not conventional, dendritic cells, suggesting a context-dependent tumour-suppressive role for TET2. These findings demonstrate how tissue-specific environmental exposures at distant anatomical sites can shape the evolution of premalignant clones to disseminated cancer.