RESUMEN
Resetting of the epigenome in human primordial germ cells (hPGCs) is critical for development. We show that the transcriptional program of hPGCs is distinct from that in mice, with co-expression of somatic specifiers and naive pluripotency genes TFCP2L1 and KLF4. This unique gene regulatory network, established by SOX17 and BLIMP1, drives comprehensive germline DNA demethylation by repressing DNA methylation pathways and activating TET-mediated hydroxymethylation. Base-resolution methylome analysis reveals progressive DNA demethylation to basal levels in week 5-7 in vivo hPGCs. Concurrently, hPGCs undergo chromatin reorganization, X reactivation, and imprint erasure. Despite global hypomethylation, evolutionarily young and potentially hazardous retroelements, like SVA, remain methylated. Remarkably, some loci associated with metabolic and neurological disorders are also resistant to DNA demethylation, revealing potential for transgenerational epigenetic inheritance that may have phenotypic consequences. We provide comprehensive insight on early human germline transcriptional network and epigenetic reprogramming that subsequently impacts human development and disease.
Asunto(s)
Epigénesis Genética , Regulación del Desarrollo de la Expresión Génica , Redes Reguladoras de Genes , Genoma Humano , Células Germinativas/metabolismo , Animales , Metilación de ADN , Embrión de Mamíferos/metabolismo , Femenino , Humanos , Factor 4 Similar a Kruppel , Masculino , Ratones , Regiones Promotoras Genéticas , RetroelementosRESUMEN
Specification of primordial germ cells (PGCs) marks the beginning of the totipotent state. However, without a tractable experimental model, the mechanism of human PGC (hPGC) specification remains unclear. Here, we demonstrate specification of hPGC-like cells (hPGCLCs) from germline competent pluripotent stem cells. The characteristics of hPGCLCs are consistent with the embryonic hPGCs and a germline seminoma that share a CD38 cell-surface marker, which collectively defines likely progression of the early human germline. Remarkably, SOX17 is the key regulator of hPGC-like fate, whereas BLIMP1 represses endodermal and other somatic genes during specification of hPGCLCs. Notable mechanistic differences between mouse and human PGC specification could be attributed to their divergent embryonic development and pluripotent states, which might affect other early cell-fate decisions. We have established a foundation for future studies on resetting of the epigenome in hPGCLCs and hPGCs for totipotency and the transmission of genetic and epigenetic information.
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Diferenciación Celular , Células Germinativas/citología , Factores de Transcripción SOXF/metabolismo , ADP-Ribosil Ciclasa 1/metabolismo , Animales , Línea Celular Tumoral , Cuerpos Embrioides/metabolismo , Células Madre Embrionarias/metabolismo , Epigénesis Genética , Células Germinativas/metabolismo , Humanos , Células Madre Pluripotentes Inducidas/metabolismo , Ratones , Factor 1 de Unión al Dominio 1 de Regulación Positiva , Proteínas Represoras/metabolismo , Seminoma/metabolismo , Análisis de Secuencia de ARNRESUMEN
Human primordial germ cells (hPGCs), the precursors of sperm and eggs, originate during weeks 2-3 of early post-implantation development. Using in vitro models of hPGC induction, recent studies have suggested that there are marked mechanistic differences in the specification of human and mouse PGCs. This may be due in part to the divergence in their pluripotency networks and early post-implantation development. As early human embryos are not accessible for direct study, we considered alternatives including porcine embryos that, as in humans, develop as bilaminar embryonic discs. Here we show that porcine PGCs originate from the posterior pre-primitive-streak competent epiblast by sequential upregulation of SOX17 and BLIMP1 in response to WNT and BMP signalling. We use this model together with human and monkey in vitro models simulating peri-gastrulation development to show the conserved principles of epiblast development for competency for primordial germ cell fate. This process is followed by initiation of the epigenetic program and regulated by a balanced SOX17-BLIMP1 gene dosage. Our combinatorial approach using human, porcine and monkey in vivo and in vitro models provides synthetic insights into early human development.
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Diferenciación Celular , Desarrollo Embrionario , Células Germinativas/citología , Macaca fascicularis/embriología , Modelos Biológicos , Células Madre Pluripotentes/citología , Porcinos/embriología , Animales , Proteínas Morfogenéticas Óseas/metabolismo , Linaje de la Célula , Cuerpos Embrioides/citología , Epigénesis Genética , Femenino , Gastrulación , Dosificación de Gen , Células Germinativas/metabolismo , Estratos Germinativos/citología , Humanos , Técnicas In Vitro , Masculino , Modelos Animales , Factor 1 de Unión al Dominio 1 de Regulación Positiva , Línea Primitiva/citología , Proteínas Represoras/genética , Factores de Transcripción SOXF/genética , Vía de Señalización WntRESUMEN
Primordial germ cells (PGCs), the precursors of sperm and eggs, are established in perigastrulation-stage embryos in mammals. Signals from extra-embryonic tissues induce a unique gene regulatory network in germline-competent cells for PGC specification. This network also initiates comprehensive epigenome resetting, including global DNA demethylation and chromatin reorganization. Mouse germline development has been studied extensively, but the extent to which such knowledge applies to humans was unclear. Here, we review the latest advances in human PGC specification and epigenetic reprogramming. The overall developmental dynamics of human and mouse germline cells appear to be similar, but there are crucial mechanistic differences in PGC specification, reflecting divergence in the regulation of pluripotency and early development.
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Metilación de ADN , Epigénesis Genética/genética , Regulación del Desarrollo de la Expresión Génica , Redes Reguladoras de Genes , Células Germinativas , Animales , Humanos , Ratones , Transducción de SeñalRESUMEN
The patient is a 73-year-old man who was diagnosed with perianal Paget's disease by skin biopsy. Biopsy from the dentate line did not show any tumor cells. The patient was considered to undergo sphincter-preserving local resection and subsequently underwent the procedure. Histopathological examination of the resected specimen revealed perianal Paget's disease with a positive anorectal margin. The patient was referred to our department due to postoperative anal stenosis. On the 32nd postoperative day, a double barreled sigmoid colostomy was performed. However, considering the inability to adequately check for detect due to anorectal stenosis and the expected unfavorable anorectal function caused by sphincter- preserving re-operation, a robot-assisted abdominoperineal resection(D1)was performed 7 months after the initial surgery. Histopathological examination of the resected specimen revealed no residual tumor cells in the resected specimen. After local excision for perianal Paget's disease, the skin of the buttock becomes scarred due to skin valve formation and skin grafting, making closure of the perineal wound difficult when performing abdominoperineal resection. In robot-assisted surgery, it is relatively easy to remove the anorectal muscles from the abdominal cavity and reach the sciatico-rectal fossa, thus reducing the size of the perineal wound.
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Neoplasias del Ano , Enfermedad de Paget Extramamaria , Procedimientos Quirúrgicos Robotizados , Neoplasias Cutáneas , Masculino , Humanos , Anciano , Enfermedad de Paget Extramamaria/cirugía , Enfermedad de Paget Extramamaria/etiología , Neoplasias del Ano/patología , Procedimientos Quirúrgicos Robotizados/efectos adversos , Recto/patología , Canal Anal/cirugía , Canal Anal/patología , Neoplasias Cutáneas/patologíaRESUMEN
Chemotherapy is the standard treatment for unresectable gastric cancer, but there is no clear evidence of therapeutic lymphadenectomy in conversion surgery after the tumor shrinks or the combined effect of perioperative chemotherapy. A 63-year-old man was diagnosed with advanced gastric cancer by upper gastrointestinal endoscopy; computed tomography (CT)showed swelling of the gastric regional lymph nodes, abdominal para-aortic lymph nodes, and left supraclavicular lymph node. After 4 courses of combination therapy with S-1 and cisplatin(SP therapy), CT showed that the left supraclavicular lymph node disappeared and the para-aortic lymph node was reduced. Distal gastrectomy and D2 plus para-aortic lymph node dissection were performed as conversion surgery. Two courses of postoperative SP therapy were administered, and S-1 monotherapy was continued for 2 years and 6 months. After 5 years and 1 month since the operation, the patient is alive without recurrence. This case shows that SP therapy can be effective as chemotherapy for unresectable gastric cancer. In addition, that conversion surgery after chemotherapy may contribute to recurrence-free survival.
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Neoplasias Gástricas , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Gastrectomía , Humanos , Escisión del Ganglio Linfático , Ganglios Linfáticos , Metástasis Linfática , Masculino , Persona de Mediana Edad , Recurrencia Local de Neoplasia , Neoplasias Gástricas/tratamiento farmacológico , Neoplasias Gástricas/cirugíaRESUMEN
In humans, germline competency and the specification of primordial germ cells (PGCs) are thought to occur in a restricted developmental window during early embryogenesis. Despite the importance of specifying the appropriate number of PGCs for human reproduction, the molecular mechanisms governing PGC formation remain largely unexplored. Here, we compared PGC-like cell (PGCLC) differentiation from 18 independently derived human embryonic stem cell (hESC) lines, and discovered that the expression of primitive streak genes were positively associated with hESC germline competency. Furthermore, we show that chemical inhibition of TGFß and WNT signaling, which are required for primitive streak formation and CRISPR/Cas9 deletion of Eomesodermin (EOMES), significantly impacts PGCLC differentiation from hESCs. Taken together, our results suggest that human PGC formation involves signaling and transcriptional programs associated with somatic germ layer induction and expression of EOMES.
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Diferenciación Celular , Células Germinativas/citología , Células Madre Embrionarias Humanas/citología , Transducción de Señal , Sistemas CRISPR-Cas , Línea Celular , Femenino , Regulación del Desarrollo de la Expresión Génica , Humanos , Masculino , Análisis de Secuencia de ARN , Proteínas de Dominio T Box/fisiologíaRESUMEN
Many animals acquire otherwise inaccessible food with the aid of sticks and occasionally water. As an exception, some reports suggest that elephants manipulate breathing through their trunks to acquire inaccessible food. Here, we report on two female Asian elephants (Elephas maximus) in Kamine Zoo, Japan, who regularly blew to drive food within their reach. We experimentally investigated this behaviour by placing foods in inaccessible places. The elephants blew the food until it came within accessible range. Once the food was within range, the elephants were increasingly less likely to blow as the distance to the food became shorter. One subject manipulated her blowing duration based on food distance: longer when the food was distant. These results suggest that the elephants used their breath to achieve goals: that is, they used it not only to retrieve the food but also to fine-tune the food position for easy grasping. We also observed individual differences in the elephants' aptitude for this technique, which altered the efficiency of food acquisition. Thus, we added a new example of spontaneous behaviour for achieving a goal in animals. The use of breath to drive food is probably unique to elephants, with their dexterous trunks and familiarity with manipulating the act of blowing, which is commonly employed for self-comfort and acoustic communication.
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Elefantes/psicología , Espiración , Solución de Problemas , Animales , Animales de Zoológico , FemeninoRESUMEN
Germ cells are unique cell types that generate a totipotent zygote upon fertilization, giving rise to the next generation in mammals and many other multicellular organisms. How germ cells acquire this ability has been of considerable interest. In mammals, primordial germ cells (PGCs), the precursors of sperm and oocytes, are specified around the time of gastrulation. PGCs are induced by signals from the surrounding extra-embryonic tissues to the equipotent epiblast cells that give rise to all cell types. Currently, the mechanism of PGC specification in mammals is best understood from studies in mice. Following implantation, the epiblast cells develop as an egg cylinder while the extra-embryonic ectoderm cells which are the source of important signals for PGC specification are located over the egg cylinder. However, in most cases, including humans, the epiblast cells develop as a planar disc, which alters the organization and the source of the signaling for cell fates. This, in turn, might have an effect on the precise mechanism of PGC specification in vivo as well as in vitro using pluripotent embryonic stem cells. Here, we discuss how the key early embryonic differences between rodents and other mammals may affect the establishment of the pluripotency network in vivo and in vitro, and consequently the basis for PGC specification, particularly from pluripotent embryonic stem cells in vitro.
RESUMEN
Human primordial germ cell (PGC) development initiates about 2 weeks after fertilization during embryogenesis. Unique molecular events follow, including epigenetic resetting, to establish functional gametes (egg and sperm). Due to the inaccessibility of human embryos, it is essential to have an amenable experimental platform to investigate the mechanisms and potential dysfunctions of the events. We previously established a PGC-like cell (PGCLC) differentiation method using human pluripotent stem cells (PSCs) via induction of precursor cells followed by stimulation with a cytokine cocktail including BMP. We also revealed that the expression of PGC specifiers, SOX17 and PRDM1, can robustly induce PGCLCs from PSCs without the cytokines. The balance of SOX17 and PRDM1 is critical for germ cell fate since the two factors also regulate endoderm differentiation. Here we describe a detailed procedure for PGCLC differentiation with the balanced induction of SOX17 and PRDM1. The protocol can be used for PGC induction in other mammalian species exhibiting PGCs with SOX17 expression. Together, these studies will advance the understanding of germ cell biology and its applications in reproductive technology and medicine.
Asunto(s)
Células Madre Pluripotentes , Semen , Animales , Humanos , Masculino , Diferenciación Celular/fisiología , Células Germinativas/metabolismo , Embrión de Mamíferos , Mamíferos , Factores de Transcripción SOXF/genética , Factores de Transcripción SOXF/metabolismo , Factor 1 de Unión al Dominio 1 de Regulación Positiva/genética , Factor 1 de Unión al Dominio 1 de Regulación Positiva/metabolismoRESUMEN
Germline commitment following primordial germ cell (PGC) specification during early human development establishes an epigenetic programme and competence for gametogenesis. Here we follow the progression of nascent PGC-like cells derived from human embryonic stem cells in vitro. We show that switching from BMP signalling for PGC specification to Activin A and retinoic acid resulted in DMRT1 and CDH5 expression, the indicators of migratory PGCs in vivo. Moreover, the induction of DMRT1 and SOX17 in PGC-like cells promoted epigenetic resetting with striking global enrichment of 5-hydroxymethylcytosine and locus-specific loss of 5-methylcytosine at DMRT1 binding sites and the expression of DAZL representing DNA methylation-sensitive genes, a hallmark of the germline commitment programme. We provide insight into the unique role of DMRT1 in germline development for advances in human germ cell biology and in vitro gametogenesis.
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Metilación de ADN , Células Madre Embrionarias Humanas , Humanos , Diferenciación Celular/genética , Células Germinativas/metabolismo , Transducción de SeñalRESUMEN
Paragangliomas are neural-crest-derived nonepithelial neuroendocrine tumors distributed along the parasympathetic and sympathetic nerves. To our knowledge, no studies were reported regarding sinus arrest on day 4 after paraganglioma resection. A 66-year-old female patient with a history of pulmonary vein isolation visited our department for sigmoid colon cancer treatment. Enhanced computed tomography revealed an enhanced small nodule-like lymph node near the root of the inferior mesenteric artery. The patient underwent laparoscopic colectomy with regional lymph node dissection. Postoperatively, paroxysmal atrial fibrillation attacks developed, and the patient resumed oral medication. Additionally, sinus arrest after tachycardia developed. Changing the oral medication could maintain her circulatory dynamics. Pathological examination revealed that differentiated tubular adenocarcinoma infiltrated the submucosa. Immunohistochemically, the excised nodule as a lymph node was considered a functional paraganglioma. Our case indicates that paraganglioma resection and oral medication resumption may contribute to sinus arrest. When arrhythmias affecting the circulation occur perioperatively, the presence of a catecholamine-producing tumor should be considered in addition to cardiac disease. J. Med. Invest. 70 : 503-507, August, 2023.
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Escisión del Ganglio Linfático , Paraganglioma , Humanos , Femenino , Anciano , Escisión del Ganglio Linfático/métodos , Tomografía Computarizada por Rayos X , Paraganglioma/diagnóstico por imagen , Paraganglioma/cirugíaRESUMEN
Germline-soma segregation is a fundamental event during mammalian embryonic development. Here we establish the epigenetic principles of human primordial germ cell (hPGC) development using in vivo hPGCs and stem cell models recapitulating gastrulation. We show that morphogen-induced remodelling of mesendoderm enhancers transiently confers the competence for hPGC fate, but further activation favours mesoderm and endoderm fates. Consistently, reducing the expression of the mesendodermal transcription factor OTX2 promotes the PGC fate. In hPGCs, SOX17 and TFAP2C initiate activation of enhancers to establish a core germline programme, including the transcriptional repressor PRDM1 and pluripotency factors POU5F1 and NANOG. We demonstrate that SOX17 enhancers are the critical components in the regulatory circuitry of germline competence. Furthermore, activation of upstream cis-regulatory elements by an optimized CRISPR activation system is sufficient for hPGC specification. We reveal an enhancer-linked germline transcription factor network that provides the basis for the evolutionary divergence of mammalian germlines.
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Gastrulación , Células Germinativas , Animales , Diferenciación Celular/genética , Desarrollo Embrionario/genética , Endodermo , Regulación del Desarrollo de la Expresión Génica , Células Germinativas/metabolismo , Humanos , MamíferosRESUMEN
BACKGROUND: Falciform ligament abscess (FLA) is a rare disease, and its diagnosis can be challenging without typical image findings of an abscess. We report a patient with FLA that presented as a mass, with an indistinct border between it and the liver, in addition to disseminated foci within the liver. This made it difficult to determine whether it was FLA or a malignancy. CASE PRESENTATION: A 69-year-old man presented with epigastric pain. Contrast-enhanced computed tomography revealed a 25-mm mass below the middle of the diaphragm. Based on an initial diagnosis of infection of the falciform ligament, we administered conservative antibiotic treatment and there was initial improvement in the patient's clinical condition and laboratory data. However, he continued to experience mild epigastric pain. A month later, imaging studies revealed enlargement of the falciform ligament mass and the emergence of a new nodule in the liver, whereas laboratory findings showed re-elevated C-reactive protein levels. Since conservative treatment had failed, we decided to perform surgery. Considering the imaging study findings, malignant disease could not be ruled out. Based on the operative findings, we performed combined resection of the falciform ligament, left liver, and gallbladder. Histopathological examination of the resected specimens revealed extensive neutrophil infiltration and the presence of giant cells and foam cells within the lesions. These findings were indicative of abscess. Pseudomonas aeruginosa was cultured from the pus in the falciform ligament mass and bile in the gallbladder. Although multiple abscesses postoperatively developed in the residual portion of the liver, they could be treated through antibiotic therapy. CONCLUSIONS: FLA can spread to both adjacent and distant organs via its rich vascular and lymphatic networks. When FLA displays atypical image findings and/or an atypical clinical course, it can be difficult to distinguish it from malignant disease. In such cases, surgical treatment, with intraoperative pathological diagnosis, should be attempted.
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Bone homeostasis requires a delicate balance between the activities of bone-resorbing osteoclasts and bone-forming osteoblasts. Various molecules coordinate osteoclast function with that of osteoblasts; however, molecules that mediate osteoclast-osteoblast interactions by simultaneous signal transduction in both cell types have not yet been identified. Here we show that osteoclasts express the NFATc1 target gene Efnb2 (encoding ephrinB2), while osteoblasts express the receptor EphB4, along with other ephrin-Eph family members. Using gain- and loss-of-function experiments, we demonstrate that reverse signaling through ephrinB2 into osteoclast precursors suppresses osteoclast differentiation by inhibiting the osteoclastogenic c-Fos-NFATc1 cascade. In addition, forward signaling through EphB4 into osteoblasts enhances osteogenic differentiation, and overexpression of EphB4 in osteoblasts increases bone mass in transgenic mice. These data demonstrate that ephrin-Eph bidirectional signaling links two major molecular mechanisms for cell differentiation--one in osteoclasts and the other in osteoblasts--thereby maintaining bone homeostasis.
Asunto(s)
Huesos/fisiología , Efrina-B2/fisiología , Homeostasis , Receptor EphB4/metabolismo , Transducción de Señal , Animales , Secuencia de Bases , Diferenciación Celular/efectos de los fármacos , Células Cultivadas , Efrina-B2/genética , Efrina-B2/farmacología , Ratones , Ratones Transgénicos , Datos de Secuencia Molecular , Factores de Transcripción NFATC/antagonistas & inhibidores , Factores de Transcripción NFATC/metabolismo , Osteoblastos/citología , Osteoclastos/citología , Proteínas Proto-Oncogénicas c-fos/antagonistas & inhibidores , Proteínas Proto-Oncogénicas c-fos/metabolismo , Receptor EphB4/genética , Regulación hacia ArribaRESUMEN
We have recently described a class of 756 genes that are widely expressed in cancers, but are normally restricted to adult germ cells, referred to as germ cell cancer genes (GC genes). We hypothesized that carcinogenesis involves the reactivation of biomolecular processes and regulatory mechanisms that, under normal circumstances, are restricted to germline development. This would imply that cancer cells share gene expression profiles with primordial germ cells (PGCs). We therefore compared the transcriptomes of human PGCs (hPGCs) and PGC-like cells (PGCLCs) with 17,382 samples from 54 healthy somatic tissues (GTEx) and 11,003 samples from 33 tumor types (TCGA), and identified 672 GC genes, expanding the known GC gene pool by 387 genes (51%). We found that GC genes are expressed in clusters that are often expressed in multiple tumor types. Moreover, the amount of GC gene expression correlates with poor survival in patients with lung adenocarcinoma. As GC genes specific to the embryonic germline are not expressed in any adult tissue, targeting these in cancer treatment may result in fewer side effects than targeting conventional cancer/testis (CT) or GC genes and may preserve fertility. We anticipate that our extended GC dataset enables improved understanding of tumor development and may provide multiple novel targets for cancer treatment development.
RESUMEN
BACKGROUND: Pancreaticoduodenectomy (PD) is rarely performed for pancreatic cancer with hepatic arterial invasion owing to its poor prognosis and high surgical risks. Although there has been a recent increase in the reports of PD combined with hepatic arterial resection due to improvements in disease prognosis and operative safety, PD with major arterial resection and reconstruction is still considered a challenging treatment. CASE PRESENTATION: A 61-year-old man with back pain was diagnosed with pancreatic head and body cancer. Although distant metastasis was not confirmed, the tumor had extensively invaded the hepatic artery; therefore, we diagnosed the patient with locally advanced unresectable pancreatic cancer. After gemcitabine plus nab-paclitaxel (GnP) therapy, the tumor considerably decreased in size from 35 to 20 mm. Magnetic resonance imaging revealed a gap between the tumor and the hepatic artery. Tumor marker levels returned to their normal range, and we decided to perform conversion surgery. In this case, an artery of liver segment 2 (A2) had branched from the left gastric artery; therefore, we decided to preserve A2 and perform PD combined with hepatic arterial resection without reconstruction. After four cycles of GnP therapy, we performed hepatic arterial embolization to prevent postoperative ischemic complications prior to surgery. Immediately after embolization, collateral arterial blood flow to the liver was observed. Operation was performed 19 days after embolization. Although there was a temporary increase in liver enzyme levels and an ischemic region was found near the surface of segment 8 of the liver after surgery, no liver abscess developed. The postoperative course was uneventful, and S-1 was administered for a year as adjuvant chemotherapy. The patient is currently alive without any ischemic liver events and cholangitis and has not experienced recurrence in the past 4 years since the surgery. CONCLUSIONS: In PD for pancreatic cancer with hepatic arterial invasion, if a part of the hepatic artery is aberrant and can be preserved, combined resection of the common and proper hepatic artery without reconstruction might be feasible for both curability and safety.
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Cells in osteoclast and osteoblast lineages communicate with each other through cell-cell contact, diffusible paracrine factors and cell-bone matrix interaction. Osteoclast-osteoblast communication occurs in a basic multicellular unit (BMU) at the initiation, transition and termination phases of bone remodeling. At the initiation phase, hematopoietic precursors are recruited to the BMU. These precursors express cell surface receptors including c-Fms, RANK and costimulatory molecules, such as osteoclast-associated receptor (OSCAR), and differentiate into osteoclasts following cell-cell contact with osteoblasts, which express ligands. Subsequently, the transition from bone resorption to formation is mediated by osteoclast-derived 'coupling factors', which direct the differentiation and activation of osteoblasts in resorbed lacunae to refill it with new bone. Bidirectional signaling generated by interaction between ephrinB2 on osteoclasts and EphB4 on osteoblast precursors facilitates the transition. Such interaction is likely to occur between osteoclasts and lining cells in the bone remodeling compartment (BRC). At the termination phase, bone remodeling is completed by osteoblastic bone formation and mineralization of bone matrix. Here, we describe molecular communication between osteoclasts and osteoblasts at distinct phases of bone remodeling.
Asunto(s)
Remodelación Ósea/fisiología , Comunicación Celular , Osteoblastos/fisiología , Osteoclastos/fisiología , Receptores de Superficie Celular/metabolismo , Animales , Resorción Ósea/metabolismo , Resorción Ósea/patología , Diferenciación Celular , Efrinas/fisiología , Humanos , Osteoblastos/citología , Osteoclastos/citología , Ligando RANK/metabolismo , Receptor de Factor Estimulante de Colonias de Macrófagos/metabolismo , Transducción de SeñalRESUMEN
Fusion of sperm and egg generates a totipotent zygote that develops into a whole organism. Accordingly, the "immortal" germline transmits genetic and epigenetic information to subsequent generations with consequences for human health and disease. In mammals, primordial germ cells (PGCs) originate from peri-gastrulation embryos. While early human embryos are inaccessible for research, in vitro model systems using pluripotent stem cells have provided critical insights into human PGC specification, which differs from that in mice. This might stem from significant differences in early embryogenesis at the morphological and molecular levels, including pluripotency networks. Here, we discuss recent advances and experimental systems used to study mammalian germ cell development. We also highlight key aspects of germ cell disorders, as well as mitochondrial and potentially epigenetic inheritance in humans.
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Células Germinativas/citología , Modelos Biológicos , Células Madre/citología , Animales , Embrión de Mamíferos/citología , Epigénesis Genética , Humanos , Factores de Transcripción/metabolismoRESUMEN
Dysregulation of genetic pathways during human germ cell development leads to infertility. Here, we analysed bona fide human primordial germ cells (hPGCs) to probe the developmental genetics of human germ cell specification and differentiation. We examined the distribution of OCT4 occupancy in hPGCs relative to human embryonic stem cells (hESCs). We demonstrated that development, from pluripotent stem cells to germ cells, is driven by switching partners with OCT4 from SOX2 to PAX5 and PRDM1. Gain- and loss-of-function studies revealed that PAX5 encodes a critical regulator of hPGC development. Moreover, an epistasis analysis indicated that PAX5 acts upstream of OCT4 and PRDM1. The PAX5-OCT4-PRDM1 proteins form a core transcriptional network that activates germline and represses somatic programmes during human germ cell differentiation. These findings illustrate the power of combined genome editing, cell differentiation and engraftment for probing human developmental genetics that have historically been difficult to study.