RESUMO
The immunosuppressive tumor microenvironment (TME) is a major barrier to immunotherapy. Within solid tumors, why monocytes preferentially differentiate into immunosuppressive tumor-associated macrophages (TAMs) rather than immunostimulatory dendritic cells (DCs) remains unclear. Using multiple murine sarcoma models, we find that the TME induces tumor cells to produce retinoic acid (RA), which polarizes intratumoral monocyte differentiation toward TAMs and away from DCs via suppression of DC-promoting transcription factor Irf4. Genetic inhibition of RA production in tumor cells or pharmacologic inhibition of RA signaling within TME increases stimulatory monocyte-derived cells, enhances T cell-dependent anti-tumor immunity, and synergizes with immune checkpoint blockade. Furthermore, an RA-responsive gene signature in human monocytes correlates with an immunosuppressive TME in multiple human tumors. RA has been considered as an anti-cancer agent, whereas our work demonstrates its tumorigenic capability via myeloid-mediated immune suppression and provides proof of concept for targeting this pathway for tumor immunotherapy.
Assuntos
Monócitos/imunologia , Tretinoína/metabolismo , Microambiente Tumoral/imunologia , Animais , Carcinogênese/patologia , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/imunologia , Linhagem Celular Tumoral , Células Dendríticas/imunologia , Humanos , Terapia de Imunossupressão/métodos , Imunoterapia/métodos , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Monócitos/metabolismoRESUMO
Ligation of retinoic acid receptor alpha (RARα) by RA promotes varied transcriptional programs associated with immune activation and tolerance, but genetic deletion approaches suggest the impact of RARα on TCR signaling. Here, we examined whether RARα would exert roles beyond transcriptional regulation. Specific deletion of the nuclear isoform of RARα revealed an RARα isoform in the cytoplasm of T cells. Extranuclear RARα was rapidly phosphorylated upon TCR stimulation and recruited to the TCR signalosome. RA interfered with extranuclear RARα signaling, causing suboptimal TCR activation while enhancing FOXP3+ regulatory T cell conversion. TCR activation induced the expression of CRABP2, which translocates RA to the nucleus. Deletion of Crabp2 led to increased RA in the cytoplasm and interfered with signalosome-RARα, resulting in impaired anti-pathogen immunity and suppressed autoimmune disease. Our findings underscore the significance of subcellular RA/RARα signaling in T cells and identify extranuclear RARα as a component of the TCR signalosome and a determinant of immune responses.
Assuntos
Doenças Autoimunes , Ativação Linfocitária , Humanos , Receptor alfa de Ácido Retinoico/genética , Membrana Celular , Receptores de Antígenos de Linfócitos TRESUMO
During development, lymph node (LN) initiation is coordinated by lymphoid tissue organizer (LTo) cells that attract lymphoid tissue inducer (LTi) cells at strategic positions within the embryo. The identity and function of LTo cells during the initial attraction of LTi cells remain poorly understood. Using lineage tracing, we demonstrated that a subset of Osr1-expressing cells was mesenchymal LTo progenitors. By investigating the heterogeneity of Osr1+ cells, we uncovered distinct mesenchymal LTo signatures at diverse anatomical locations, identifying a common progenitor of mesenchymal LTos and LN-associated adipose tissue. Osr1 was essential for LN initiation, driving the commitment of mesenchymal LTo cells independent of neural retinoic acid, and for LN-associated lymphatic vasculature assembly. The combined action of chemokines CXCL13 and CCL21 was required for LN initiation. Our results redefine the role and identity of mesenchymal organizer cells and unify current views by proposing a model of cooperative cell function in LN initiation.
Assuntos
Organogênese , Fatores de Transcrição , Diferenciação Celular , Linfonodos , Tecido LinfoideRESUMO
There is growing recognition that regionalization of bacterial colonization and immunity along the intestinal tract has an important role in health and disease. Yet, the mechanisms underlying intestinal regionalization and its dysregulation in disease are not well understood. This study found that regional epithelial expression of the transcription factor GATA4 controls bacterial colonization and inflammatory tissue immunity in the proximal small intestine by regulating retinol metabolism and luminal IgA. Furthermore, in mice without jejunal GATA4 expression, the commensal segmented filamentous bacteria promoted pathogenic inflammatory immune responses that disrupted barrier function and increased mortality upon Citrobacter rodentium infection. In celiac disease patients, low GATA4 expression was associated with metabolic alterations, mucosal Actinobacillus, and increased IL-17 immunity. Taken together, these results reveal broad impacts of GATA4-regulated intestinal regionalization on bacterial colonization and tissue immunity, highlighting an elaborate interdependence of intestinal metabolism, immunity, and microbiota in homeostasis and disease.
Assuntos
Infecções por Enterobacteriaceae , Fator de Transcrição GATA4 , Microbioma Gastrointestinal , Mucosa Intestinal , Animais , Humanos , Camundongos , Actinobacillus , Microbioma Gastrointestinal/imunologia , Fator de Transcrição GATA4/metabolismo , Imunidade nas Mucosas , Interleucina-17/imunologia , Interleucina-17/metabolismo , Mucosa Intestinal/imunologia , Mucosa Intestinal/microbiologia , Intestino Delgado , SimbioseRESUMO
Early-life establishment of tolerance to commensal bacteria at barrier surfaces carries enduring implications for immune health but remains poorly understood. Here, we showed that tolerance in skin was controlled by microbial interaction with a specialized subset of antigen-presenting cells. More particularly, CD301b+ type 2 conventional dendritic cells (DCs) in neonatal skin were specifically capable of uptake and presentation of commensal antigens for the generation of regulatory T (Treg) cells. CD301b+ DC2 were enriched for phagocytosis and maturation programs, while also expressing tolerogenic markers. In both human and murine skin, these signatures were reinforced by microbial uptake. In contrast to their adult counterparts or other early-life DC subsets, neonatal CD301b+ DC2 highly expressed the retinoic-acid-producing enzyme, RALDH2, the deletion of which limited commensal-specific Treg cell generation. Thus, synergistic interactions between bacteria and a specialized DC subset critically support early-life tolerance at the cutaneous interface.
Assuntos
Células Dendríticas , Pele , Animais , Camundongos , Humanos , Linfócitos T Reguladores , Tolerância Imunológica , Aldeído Oxirredutases/metabolismoRESUMO
Dormant hematopoietic stem cells (dHSCs) are atop the hematopoietic hierarchy. The molecular identity of dHSCs and the mechanisms regulating their maintenance or exit from dormancy remain uncertain. Here, we use single-cell RNA sequencing (RNA-seq) analysis to show that the transition from dormancy toward cell-cycle entry is a continuous developmental path associated with upregulation of biosynthetic processes rather than a stepwise progression. In addition, low Myc levels and high expression of a retinoic acid program are characteristic for dHSCs. To follow the behavior of dHSCs in situ, a Gprc5c-controlled reporter mouse was established. Treatment with all-trans retinoic acid antagonizes stress-induced activation of dHSCs by restricting protein translation and levels of reactive oxygen species (ROS) and Myc. Mice maintained on a vitamin A-free diet lose HSCs and show a disrupted re-entry into dormancy after exposure to inflammatory stress stimuli. Our results highlight the impact of dietary vitamin A on the regulation of cell-cycle-mediated stem cell plasticity. VIDEO ABSTRACT.
Assuntos
Células-Tronco Hematopoéticas/citologia , Transdução de Sinais , Tretinoína/farmacologia , Vitamina A/administração & dosagem , Animais , Vias Biossintéticas , Técnicas de Cultura de Células , Ciclo Celular/efeitos dos fármacos , Sobrevivência Celular , Dieta , Perfilação da Expressão Gênica , Células-Tronco Hematopoéticas/efeitos dos fármacos , Camundongos , Poli I-C/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Receptores Acoplados a Proteínas G/metabolismo , Análise de Célula Única , Estresse Fisiológico , Vitamina A/farmacologia , Vitaminas/administração & dosagem , Vitaminas/farmacologiaRESUMO
The role of innate immune cells in allergen immunotherapy that confers immune tolerance to the sensitizing allergen is unclear. Here, we report a role of interleukin-10-producing type 2 innate lymphoid cells (IL-10+ ILC2s) in modulating grass-pollen allergy. We demonstrate that KLRG1+ but not KLRG1- ILC2 produced IL-10 upon activation with IL-33 and retinoic acid. These cells attenuated Th responses and maintained epithelial cell integrity. IL-10+ KLRG1+ ILC2s were lower in patients with grass-pollen allergy when compared to healthy subjects. In a prospective, double-blind, placebo-controlled trial, we demonstrated that the competence of ILC2 to produce IL-10 was restored in patients who received grass-pollen sublingual immunotherapy. The underpinning mechanisms were associated with the modification of retinol metabolic pathway, cytokine-cytokine receptor interaction, and JAK-STAT signaling pathways in the ILCs. Altogether, our findings underscore the contribution of IL-10+ ILC2s in the disease-modifying effect by allergen immunotherapy.
Assuntos
Interleucina-10/metabolismo , Linfócitos/imunologia , Rinite Alérgica Sazonal/imunologia , Imunoterapia Sublingual/métodos , Adulto , Alérgenos/imunologia , Método Duplo-Cego , Feminino , Humanos , Tolerância Imunológica , Imunidade Inata , Janus Quinases/metabolismo , Lectinas Tipo C/metabolismo , Masculino , Pessoa de Meia-Idade , Efeito Placebo , Poaceae/imunologia , Pólen/imunologia , Receptores Imunológicos/metabolismo , Rinite Alérgica Sazonal/terapia , Fatores de Transcrição STAT/metabolismo , Transdução de Sinais , Células Th2/imunologia , Resultado do Tratamento , Vitamina A/metabolismo , Adulto JovemRESUMO
Dendritic cell (DC) dysfunction is known to exacerbate intestinal pathologies, but the mechanisms compromising DC-mediated immune regulation in this context remain unclear. Here, we show that intestinal dendritic cells from a mouse model of experimental colitis exhibit significant levels of noncanonical NF-κB signaling, which activates the RelB:p52 heterodimer. Genetic inactivation of this pathway in DCs alleviates intestinal pathologies in mice suffering from colitis. Deficiency of RelB:p52 diminishes transcription of Axin1, a critical component of the ß-catenin destruction complex, reinforcing ß-catenin-dependent expression of Raldh2, which imparts tolerogenic DC attributes by promoting retinoic acid synthesis. DC-specific impairment of noncanonical NF-κB signaling leads to increased colonic numbers of Tregs and IgA+ B cells, which promote luminal IgA production and foster eubiosis. Experimentally introduced ß-catenin haploinsufficiency in DCs with deficient noncanonical NF-κB signaling moderates Raldh2 activity, reinstating colitogenic sensitivity in mice. Finally, inflammatory bowel-disease patients also display a deleterious noncanonical NF-κB signaling signature in intestinal DCs. In sum, we establish how noncanonical NF-κB signaling in dendritic cells can subvert retinoic acid synthesis to fuel intestinal inflammation.
RESUMO
Tissue-resident macrophages require specific milieus for the maintenance of defining gene-expression programs. Expression of the transcription factor GATA6 is required for the homeostasis, function and localization of peritoneal cavity-resident macrophages. Gata6 expression is maintained in a non-cell autonomous manner and is elicited by the vitamin A metabolite, retinoic acid. Here, we found that the GATA6 transcriptional program is a common feature of macrophages residing in all visceral body cavities. Retinoic acid-dependent and -independent hallmark genes of GATA6+ macrophages were induced by mesothelial and fibroblastic stromal cells that express the transcription factor Wilms' Tumor 1 (WT1), which drives the expression of two rate-limiting enzymes in retinol metabolism. Depletion of Wt1+ stromal cells reduced the frequency of GATA6+ macrophages in the peritoneal, pleural and pericardial cavities. Thus, Wt1+ mesothelial and fibroblastic stromal cells constitute essential niche components supporting the tissue-specifying transcriptional landscape and homeostasis of cavity-resident macrophages.
Assuntos
Fator de Transcrição GATA6/metabolismo , Macrófagos/fisiologia , Pericárdio/imunologia , Cavidade Peritoneal/fisiologia , Cavidade Pleural/imunologia , Proteínas Repressoras/metabolismo , Células Estromais/fisiologia , Animais , Diferenciação Celular , Células Cultivadas , Fator de Transcrição GATA6/genética , Homeostase , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas Repressoras/genética , Tretinoína/metabolismo , Proteínas WT1RESUMO
CD4+ T helper (Th) differentiation is regulated by diverse inputs, including the vitamin A metabolite retinoic acid (RA). RA acts through its receptor RARα to repress transcription of inflammatory cytokines, but is also essential for Th-mediated immunity, indicating complex effects of RA on Th specification and the outcome of the immune response. We examined the impact of RA on the genome-wide transcriptional response during Th differentiation to multiple subsets. RA effects were subset-selective and were most significant in Th9 cells. RA globally antagonized Th9-promoting transcription factors and inhibited Th9 differentiation. RA directly targeted the extended Il9 locus and broadly modified the Th9 epigenome through RARα. RA-RARα activity limited murine Th9-associated pulmonary inflammation, and human allergic inflammation was associated with reduced expression of RA target genes. Thus, repression of the Th9 program is a major function of RA-RARα signaling in Th differentiation, arguing for a role for RA in interleukin 9 (IL-9) related diseases.
Assuntos
Hipersensibilidade/imunologia , Pulmão/fisiologia , Pneumonia/imunologia , Receptor alfa de Ácido Retinoico/metabolismo , Linfócitos T Auxiliares-Indutores/fisiologia , Animais , Repressão Epigenética , Células HEK293 , Humanos , Hipersensibilidade/genética , Interleucina-9/metabolismo , Pulmão/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pneumonia/genética , Receptor alfa de Ácido Retinoico/genética , Transdução de Sinais , Transcrição Gênica , Tretinoína/metabolismoRESUMO
The milky spots in omentum are atypical lymphoid tissues that play a pivotal role in regulating immune responses in the peritoneal cavity. The milky spots act as central hubs for collecting antigens and particles from the peritoneal cavity, regulating lymphocyte trafficking, promoting the differentiation and self-renewal of immune cells, and supporting the local germinal centre response. In addition, the milky spots exhibit unique developmental characteristics that combine the features of secondary and tertiary lymphoid tissues. These structures are innately programmed to form during foetal development; however, they can also be formed postnatally in response to peritoneal irritation such as inflammation, infection, obesity, or tumour metastasis. In this review, I discuss emerging perspectives on homeostatic development and organization of the milky spots.
Assuntos
Omento , Humanos , Animais , Omento/imunologia , Diferenciação Celular , Homeostase , Tecido Linfoide/imunologia , Centro Germinativo/imunologia , Cavidade PeritonealRESUMO
Meiosis is essential for gamete production in all sexually reproducing organisms. It entails two successive cell divisions without DNA replication, producing haploid cells from diploid ones. This process involves complex morphological and molecular differentiation that varies across species and between sexes. Specialized genomic events like meiotic recombination and chromosome segregation are tightly regulated, including preparation for post-meiotic development. Research in model organisms, notably yeast, has shed light on the genetic and molecular aspects of meiosis and its regulation. Although mammalian meiosis research faces challenges, particularly in replicating gametogenesis in vitro, advances in genetic and genomic technologies are providing mechanistic insights. Here we review the genetics and molecular biology of meiotic gene expression control, focusing on mammals.
Assuntos
Meiose , Saccharomyces cerevisiae , Animais , Meiose/genética , Saccharomyces cerevisiae/genética , Gametogênese/genética , Segregação de Cromossomos/genética , Replicação do DNA , MamíferosRESUMO
Skeletal muscles of the head and trunk originate in distinct lineages with divergent regulatory programs converging on activation of myogenic determination factors. Branchiomeric head and neck muscles share a common origin with cardiac progenitor cells in cardiopharyngeal mesoderm (CPM). The retinoic acid (RA) signalling pathway is required during a defined early time window for normal deployment of cells from posterior CPM to the heart. Here we show that blocking RA signalling in the early mouse embryo also results in selective loss of the trapezius neck muscle, without affecting other skeletal muscles. RA signalling is required for robust expression of myogenic determination factors in posterior CPM and subsequent expansion of the trapezius primordium. Lineage specific activation of a dominant negative RA receptor reveals that trapezius development is not regulated by direct RA signalling to myogenic progenitor cells in CPM, or through neural crest cells, but indirectly through the somitic lineage, closely apposed with posterior CPM in the early embryo. These findings suggest that trapezius development is dependent on precise spatiotemporal interactions between cranial and somitic mesoderm at the head/trunk interface.
RESUMO
Retinoic acid (RA), a vitamin A metabolite, regulates transcriptional programs that drive protective or pathogenic immune responses in the intestine, in a manner dependent on RA concentration. Vitamin A is obtained from diet and is metabolized by intestinal epithelial cells (IECs), which operate in intimate association with microbes and immune cells. Here we found that commensal bacteria belonging to class Clostridia modulate RA concentration in the gut by suppressing the expression of retinol dehydrogenase 7 (Rdh7) in IECs. Rdh7 expression and associated RA amounts were lower in the intestinal tissue of conventional mice, as compared to germ-free mice. Deletion of Rdh7 in IECs diminished RA signaling in immune cells, reduced the IL-22-dependent antimicrobial response, and enhanced resistance to colonization by Salmonella Typhimurium. Our findings define a regulatory circuit wherein bacterial regulation of IEC-intrinsic RA synthesis protects microbial communities in the gut from excessive immune activity, achieving a balance that prevents colonization by enteric pathogens.
Assuntos
Disbiose/metabolismo , Células Epiteliais/metabolismo , Interleucinas/metabolismo , Mucosa Intestinal/metabolismo , Tretinoína/metabolismo , Oxirredutases do Álcool/genética , Oxirredutases do Álcool/metabolismo , Animais , Bactérias/classificação , Bactérias/genética , Disbiose/microbiologia , Células Epiteliais/microbiologia , Interações entre Hospedeiro e Microrganismos , Mucosa Intestinal/citologia , Mucosa Intestinal/microbiologia , Linfócitos/metabolismo , Linfócitos/microbiologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microbiota/genética , Microbiota/fisiologia , RNA Ribossômico 16S/genética , Salmonella typhimurium/genética , Salmonella typhimurium/fisiologia , Simbiose , Interleucina 22RESUMO
Eosinophils are well recognized as effector cells of type 2 immunity, yet they also accumulate in many tissues under homeostatic conditions. However, the processes that govern homeostatic eosinophil accumulation and tissue-specific adaptation, and their functional significance, remain poorly defined. Here, we investigated how eosinophils adapt to the small intestine (SI) microenvironment and the local signals that regulate this process. We observed that eosinophils gradually migrate along the crypt-villus axis, giving rise to a villus-resident subpopulation with a distinct transcriptional signature. Retinoic acid signaling was specifically required for maintenance of this subpopulation, while IL-5 was largely dispensable outside of its canonical role in eosinophil production. Surprisingly, we found that a high-protein diet suppressed the accumulation of villus-resident eosinophils. Purified amino acids were sufficient for this effect, which was a consequence of accelerated eosinophil turnover within the tissue microenvironment and was not due to altered development in the bone marrow. Our study provides insight into the process of eosinophil adaptation to the SI, highlighting its reliance on nutrient-derived signals.
Assuntos
Medula Óssea , Eosinófilos , Intestino Delgado , Linfócitos , TretinoínaRESUMO
Despite numerous female contraceptive options, nearly half of all pregnancies are unintended. Family planning choices for men are currently limited to unreliable condoms and invasive vasectomies with questionable reversibility. Here, we report the development of an oral contraceptive approach based on transcriptional disruption of cyclical gene expression patterns during spermatogenesis. Spermatogenesis involves a continuous series of self-renewal and differentiation programs of spermatogonial stem cells (SSCs) that is regulated by retinoic acid (RA)-dependent activation of receptors (RARs), which control target gene expression through association with corepressor proteins. We have found that the interaction between RAR and the corepressor silencing mediator of retinoid and thyroid hormone receptors (SMRT) is essential for spermatogenesis. In a genetically engineered mouse model that negates SMRT-RAR binding (SMRTmRID mice), the synchronized, cyclic expression of RAR-dependent genes along the seminiferous tubules is disrupted. Notably, the presence of an RA-resistant SSC population that survives RAR de-repression suggests that the infertility attributed to the loss of SMRT-mediated repression is reversible. Supporting this notion, we show that inhibiting the action of the SMRT complex with chronic, low-dose oral administration of a histone deacetylase inhibitor reversibly blocks spermatogenesis and fertility without affecting libido. This demonstration validates pharmacologic targeting of the SMRT repressor complex for non-hormonal male contraception.
Assuntos
Proteínas de Ligação a DNA , Proteínas Repressoras , Humanos , Feminino , Masculino , Animais , Camundongos , Proteínas de Ligação a DNA/metabolismo , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Proteínas Correpressoras/genética , Correpressor 2 de Receptor Nuclear/genética , Tretinoína/farmacologia , Anticoncepção , Correpressor 1 de Receptor NuclearRESUMO
Chronic kidney disease (CKD) is characterized by a gradual loss of kidney function and affects ~13.4% of the global population. Progressive tubulointerstitial fibrosis, driven in part by proximal tubule (PT) damage, is a hallmark of late stages of CKD and contributes to the development of kidney failure, for which there are limited treatment options. Normal kidney development requires signaling by vitamin A (retinol), which is metabolized to retinoic acid (RA), an endogenous agonist for the RA receptors (RARα, ß, γ). RARα levels are decreased in a mouse model of diabetic nephropathy and restored with RA administration; additionally, RA treatment reduced fibrosis. We developed a mouse model in which a spatiotemporal (tamoxifen-inducible) deletion of RARα in kidney PT cells of adult mice causes mitochondrial dysfunction, massive PT injury, and apoptosis without the use of additional nephrotoxic substances. Long-term effects (3 to 4.5 mo) of RARα deletion include increased PT secretion of transforming growth factor ß1, inflammation, interstitial fibrosis, and decreased kidney function, all of which are major features of human CKD. Therefore, RARα's actions in PTs are crucial for PT homeostasis, and loss of RARα causes injury and a key CKD phenotype.
Assuntos
Rim , Insuficiência Renal Crônica , Receptor alfa de Ácido Retinoico , Animais , Humanos , Camundongos , Modelos Animais de Doenças , Fibrose , Rim/metabolismo , Túbulos Renais Proximais/metabolismo , Insuficiência Renal Crônica/genética , Insuficiência Renal Crônica/prevenção & controle , Receptor alfa de Ácido Retinoico/genética , Receptor alfa de Ácido Retinoico/metabolismo , Tretinoína/farmacologia , Tretinoína/metabolismoRESUMO
According to Dollo's Law of irreversibility in evolution, a lost structure is usually considered to be unable to reappear in evolution due to the accumulation over time of mutations in the genes required for its formation. Cypriniform fish are a classic model of evolutionary loss because, while they form fully operational teeth in the ventral posterior pharynx, unlike other teleosts, they do not possess oral teeth. Paleontological data show that Cypriniforms, a clade of teleost fish that includes the zebrafish, lost their oral teeth 50 to 100 Mya. In order to attempt to reverse oral tooth loss in zebrafish, we block the degradation of endogenous levels of retinoic acid (RA) using a specific inhibitor of the Cyp26 RA degrading enzymes. We demonstrate the inhibition of endogenous RA degradation is sufficient to restore oral tooth induction as marked by the re-appearance of expression of early dental mesenchyme and epithelium genes such as dlx2b and sp7 in the oral cavity. Furthermore, we show that these exogenously induced oral tooth germs are able to be at least partly calcified. Taken together, our data show that modifications of signaling pathways can have a significant effect on the reemergence of once-lost structures leading to experimentally induced reversibility of evolutionary tooth loss in cypriniforms.
Assuntos
Perciformes , Perda de Dente , Animais , Peixe-Zebra , OdontogêneseRESUMO
Alcohol dehydrogenase 1B (ADH1B) is a primate-specific enzyme which, uniquely among the ADH class 1 family, is highly expressed both in adipose tissue and liver. Its expression in adipose tissue is reduced in obesity and increased by insulin stimulation. Interference with ADH1B expression has also been reported to impair adipocyte function. To better understand the role of ADH1B in adipocytes, we used CRISPR/Cas9 to delete ADH1B in human adipose stem cells (ASC). Cells lacking ADH1B failed to differentiate into mature adipocytes manifested by minimal triglyceride accumulation and a marked reduction in expression of established adipocyte markers. As ADH1B is capable of converting retinol to retinoic acid (RA), we conducted rescue experiments. Incubation of ADH1B-deficient preadipocytes with 9-cis-RA, but not with all-transretinol, significantly rescued their ability to accumulate lipids and express markers of adipocyte differentiation. A homozygous missense variant in ADH1B (p.Arg313Cys) was found in a patient with congenital lipodystrophy of unknown cause. This variant significantly impaired the protein's dimerization, enzymatic activity, and its ability to rescue differentiation in ADH1B-deficient ASC. The allele frequency of this variant in the Middle Eastern population suggests that it is unlikely to be a fully penetrant cause of severe lipodystrophy. In conclusion, ADH1B appears to play an unexpected, crucial and cell-autonomous role in human adipocyte differentiation by serving as a necessary source of endogenous retinoic acid.
Assuntos
Adipócitos , Adipogenia , Álcool Desidrogenase , Humanos , Álcool Desidrogenase/metabolismo , Álcool Desidrogenase/genética , Adipogenia/genética , Adipócitos/metabolismo , Adipócitos/citologia , Tretinoína/metabolismo , Diferenciação Celular , Sistemas CRISPR-Cas , Mutação de Sentido Incorreto , Tecido Adiposo/metabolismoRESUMO
Adipose stem and precursor cells (ASPCs) give rise to adipocytes and determine the composition and plasticity of adipose tissue. Recently, several studies have demonstrated that ASPCs partition into at least three distinct cell subpopulations, including the enigmatic CD142+ cells. An outstanding challenge is to functionally characterise this population, as discrepant properties, from adipogenic to non- and anti-adipogenic, have been reported for these cells. To resolve these phenotypic ambiguities, we characterised mammalian subcutaneous CD142+ ASPCs across various experimental conditions, demonstrating that CD142+ ASPCs exhibit high molecular and phenotypic robustness. Specifically, we find these cells to be firmly non- and anti-adipogenic both in vitro and in vivo, with their inhibitory signals also impacting adipogenic human cells. However, these CD142+ ASPC-specific properties exhibit surprising temporal phenotypic alterations, and emerge only in an age-dependent manner. Finally, using multi-omic and functional assays, we show that the inhibitory nature of these adipogenesis-regulatory CD142+ ASPCs (Aregs) is driven by specifically expressed secretory factors that cooperate with the retinoic acid signalling pathway to transform the adipogenic state of CD142- ASPCs into a non-adipogenic, Areg-like state.