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1.
Cell ; 187(2): 331-344.e17, 2024 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-38194964

RESUMO

Enhancers are distal DNA elements believed to loop and contact promoters to control gene expression. Recently, we found diffraction-sized transcriptional condensates at genes controlled by clusters of enhancers (super-enhancers). However, a direct function of endogenous condensates in controlling gene expression remains elusive. Here, we develop live-cell super-resolution and multi-color 3D-imaging approaches to investigate putative roles of endogenous condensates in the regulation of super-enhancer controlled gene Sox2. In contrast to enhancer distance, we find instead that the condensate's positional dynamics are a better predictor of gene expression. A basal gene bursting occurs when the condensate is far (>1 µm), but burst size and frequency are enhanced when the condensate moves in proximity (<1 µm). Perturbations of cohesin and local DNA elements do not prevent basal bursting but affect the condensate and its burst enhancement. We propose a three-way kissing model whereby the condensate interacts transiently with gene locus and regulatory DNA elements to control gene bursting.


Assuntos
Regulação da Expressão Gênica , Fatores de Transcrição SOXB1 , Super Intensificadores , Transcrição Gênica , DNA/genética , Elementos Facilitadores Genéticos , Fatores de Transcrição SOXB1/genética , Animais , Camundongos , Células-Tronco Embrionárias/metabolismo , Microscopia/métodos
2.
Cell ; 168(3): 442-459.e20, 2017 01 26.
Artigo em Inglês | MEDLINE | ID: mdl-28111071

RESUMO

Oct4, Sox2, Klf4, and cMyc (OSKM) reprogram somatic cells to pluripotency. To gain a mechanistic understanding of their function, we mapped OSKM-binding, stage-specific transcription factors (TFs), and chromatin states in discrete reprogramming stages and performed loss- and gain-of-function experiments. We found that OSK predominantly bind active somatic enhancers early in reprogramming and immediately initiate their inactivation genome-wide by inducing the redistribution of somatic TFs away from somatic enhancers to sites elsewhere engaged by OSK, recruiting Hdac1, and repressing the somatic TF Fra1. Pluripotency enhancer selection is a stepwise process that also begins early in reprogramming through collaborative binding of OSK at sites with high OSK-motif density. Most pluripotency enhancers are selected later in the process and require OS and other pluripotency TFs. Somatic and pluripotency TFs modulate reprogramming efficiency when overexpressed by altering OSK targeting, somatic-enhancer inactivation, and pluripotency enhancer selection. Together, our data indicate that collaborative interactions among OSK and with stage-specific TFs direct both somatic-enhancer inactivation and pluripotency-enhancer selection to drive reprogramming.


Assuntos
Reprogramação Celular , Fatores de Transcrição/metabolismo , Animais , Cromatina/metabolismo , Fibroblastos/metabolismo , Código das Histonas , Fator 4 Semelhante a Kruppel , Fatores de Transcrição Kruppel-Like/metabolismo , Camundongos , Fator 3 de Transcrição de Octâmero/metabolismo , Proteínas Proto-Oncogênicas c-fos/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Elementos Reguladores de Transcrição , Fatores de Transcrição SOXB1/metabolismo , Elementos Silenciadores Transcricionais
3.
Genes Dev ; 36(21-24): 1097-1099, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36622807

RESUMO

Transcription factors are defined by their sequence-specific binding to DNA and by their selective impacts on gene expression, depending on specific binding sites. The factor binding motifs in the DNA should thus represent a blueprint of regulatory logic, suggesting that transcription factor binding patterns on the genome (e.g., measured by ChIP-seq) should indicate which target genes the factors are directly controlling. However, although genetic data confirm high impacts of transcription factor perturbation in embryology, transcription factors bind to far more sites than the number of genes they dynamically regulate, when measured by direct perturbation in a given cell type. Also, deletion of carefully chosen transcription factor binding sites often gives disappointingly weak results. In a new study in the previous issue of Genes & Development, Lo and colleagues (pp. 1079-1095) reconcile these contradictions by using an elegant experimental system to directly compare the roles of transcription factor-binding site interaction in gene regulation maintenance with roles of the same factor-site interactions in gene regulation through developmental change. They examine Oct4:Sox2 shared target genes under maintained versus reinduced pluripotency conditions within the same cell clone. The results show that the same factor-site interaction impacts can appear modest in assays in developmental steady-state but are far more important as regulatory catalysts of developmental change.


Assuntos
Células-Tronco Embrionárias , Fatores de Transcrição , Fatores de Transcrição/metabolismo , Células-Tronco Embrionárias/metabolismo , Regulação da Expressão Gênica , Sítios de Ligação , Fator 3 de Transcrição de Octâmero/metabolismo , DNA/metabolismo , Fatores de Transcrição SOXB1/genética , Diferenciação Celular/genética
4.
Genes Dev ; 36(19-20): 1079-1095, 2022 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-36418052

RESUMO

Much has been learned about the mechanisms of action of pluripotency factors Oct4 and Sox2. However, as with other regulators of cell identity, little is known about the impact of disrupting their binding motifs in a native environment or the characteristics of genes they regulate. By quantitatively examining dynamic ranges of gene expression instead of focusing on conventional measures of differential expression, we found that Oct4 and Sox2 enhancer binding is strongly enriched near genes subject to large dynamic ranges of expression among cell types, with binding sites near these genes usually within superenhancers. Mutagenesis of representative Oct4:Sox2 motifs near such active, dynamically regulated genes revealed critical roles in transcriptional activation during reprogramming, with more limited roles in transcriptional maintenance in the pluripotent state. Furthermore, representative motifs near silent genes were critical for establishing but not maintaining the fully silent state, while genes whose transcript levels varied by smaller magnitudes among cell types were unaffected by nearby Oct4:Sox2 motifs. These results suggest that Oct4 and Sox2 directly establish both active and silent transcriptional states in pluripotent cells at a large number of genes subject to dynamic regulation during mammalian development, but are less important than expected for maintaining transcriptional states.


Assuntos
Aprendizagem , Mamíferos , Animais , Ativação Transcricional , Sítios de Ligação , Mutagênese
5.
Immunity ; 49(4): 764-779.e9, 2018 10 16.
Artigo em Inglês | MEDLINE | ID: mdl-30332632

RESUMO

The major types of non-small-cell lung cancer (NSCLC)-squamous cell carcinoma and adenocarcinoma-have distinct immune microenvironments. We developed a genetic model of squamous NSCLC on the basis of overexpression of the transcription factor Sox2, which specifies lung basal cell fate, and loss of the tumor suppressor Lkb1 (SL mice). SL tumors recapitulated gene-expression and immune-infiltrate features of human squamous NSCLC; such features included enrichment of tumor-associated neutrophils (TANs) and decreased expression of NKX2-1, a transcriptional regulator that specifies alveolar cell fate. In Kras-driven adenocarcinomas, mis-expression of Sox2 or loss of Nkx2-1 led to TAN recruitment. TAN recruitment involved SOX2-mediated production of the chemokine CXCL5. Deletion of Nkx2-1 in SL mice (SNL) revealed that NKX2-1 suppresses SOX2-driven squamous tumorigenesis by repressing adeno-to-squamous transdifferentiation. Depletion of TANs in SNL mice reduced squamous tumors, suggesting that TANs foster squamous cell fate. Thus, lineage-defining transcription factors determine the tumor immune microenvironment, which in turn might impact the nature of the tumor.


Assuntos
Diferenciação Celular/imunologia , Regulação Neoplásica da Expressão Gênica/imunologia , Fatores de Transcrição SOXB1/imunologia , Microambiente Tumoral/imunologia , Animais , Carcinoma Pulmonar de Células não Pequenas/genética , Carcinoma Pulmonar de Células não Pequenas/imunologia , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Diferenciação Celular/genética , Linhagem Celular Tumoral , Linhagem da Célula/genética , Linhagem da Célula/imunologia , Células Cultivadas , Modelos Animais de Doenças , Feminino , Perfilação da Expressão Gênica , Células HEK293 , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/imunologia , Neoplasias Pulmonares/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Neutrófilos/imunologia , Neutrófilos/metabolismo , Fatores de Transcrição SOXB1/genética , Fatores de Transcrição SOXB1/metabolismo , Fator Nuclear 1 de Tireoide/genética , Fator Nuclear 1 de Tireoide/metabolismo , Microambiente Tumoral/genética
6.
Mol Cell ; 73(4): 815-829.e7, 2019 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-30772174

RESUMO

Somatic cells can be reprogrammed into induced pluripotent stem cells (iPSCs), which is a highly heterogeneous process. Here we report the cell fate continuum during somatic cell reprogramming at single-cell resolution. We first develop SOT to analyze cell fate continuum from Oct4/Sox2/Klf4- or OSK-mediated reprogramming and show that cells bifurcate into two categories, reprogramming potential (RP) or non-reprogramming (NR). We further show that Klf4 contributes to Cd34+/Fxyd5+/Psca+ keratinocyte-like NR fate and that IFN-γ impedes the final transition to chimera-competent pluripotency along the RP cells. We analyze more than 150,000 single cells from both OSK and chemical reprograming and identify additional NR/RP bifurcation points. Our work reveals a generic bifurcation model for cell fate decisions during somatic cell reprogramming that may be applicable to other systems and inspire further improvements for reprogramming.


Assuntos
Diferenciação Celular/genética , Linhagem da Célula/genética , Técnicas de Reprogramação Celular , Reprogramação Celular/genética , Células-Tronco Pluripotentes Induzidas/fisiologia , Células-Tronco Embrionárias Murinas/fisiologia , Análise de Sequência de RNA , Análise de Célula Única , Animais , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Células-Tronco Pluripotentes Induzidas/metabolismo , Interferon gama/genética , Interferon gama/metabolismo , Fator 4 Semelhante a Kruppel , Masculino , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Camundongos Transgênicos , Células-Tronco Embrionárias Murinas/metabolismo , Fenótipo , Transdução de Sinais , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
7.
Bioessays ; 46(1): e2300083, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-38010492

RESUMO

Recent studies support a model in which the progeny of SOX9+ epithelial progenitors at the distal tip of lung branches undergo cell allocation and differentiation sequentially along the distal-to-proximal axis. Concomitant with the elongation and ramification of lung branches, the descendants of the distal SOX9+ progenitors are distributed proximally, express SOX2, and differentiate into cell types in the conducting airways. Amid subsequent sacculation, the distal SOX9+ progenitors generate alveolar epithelial cells to form alveoli. Sequential cell allocation and differentiation are integrated with the branching process to generate a functional branching organ. This review focuses on the roles of SOX9+ cells as precursors for new branches, as the source of various cell types in the conducting airways, and as progenitors of the alveolar epithelium. All of these processes are controlled by multiple signaling pathways. Many mouse mutants with defective lung branching contain underlying defects in one or more steps of cell allocation and differentiation of SOX9+ progenitors. This model provides a framework to understand the molecular basis of lung phenotypes and to elucidate the molecular mechanisms of lung patterning. It builds a foundation on which comparing and contrasting the mechanisms employed by different branching organs in diverse species can be made.


Assuntos
Pulmão , Alvéolos Pulmonares , Camundongos , Animais , Pulmão/metabolismo , Diferenciação Celular , Transdução de Sinais
8.
Proc Natl Acad Sci U S A ; 120(23): e2220037120, 2023 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-37252980

RESUMO

The balance between neural stem cell proliferation and neuronal differentiation is paramount for the appropriate development of the nervous system. Sonic hedgehog (Shh) is known to sequentially promote cell proliferation and specification of neuronal phenotypes, but the signaling mechanisms responsible for the developmental switch from mitogenic to neurogenic have remained unclear. Here, we show that Shh enhances Ca2+ activity at the neural cell primary cilium of developing Xenopus laevis embryos through Ca2+ influx via transient receptor potential cation channel subfamily C member 3 (TRPC3) and release from intracellular stores in a developmental stage-dependent manner. This ciliary Ca2+ activity in turn antagonizes canonical, proliferative Shh signaling in neural stem cells by down-regulating Sox2 expression and up-regulating expression of neurogenic genes, enabling neuronal differentiation. These discoveries indicate that the Shh-Ca2+-dependent switch in neural cell ciliary signaling triggers the switch in Shh action from canonical-mitogenic to neurogenic. The molecular mechanisms identified in this neurogenic signaling axis are potential targets for the treatment of brain tumors and neurodevelopmental disorders.


Assuntos
Cálcio , Proteínas Hedgehog , Proteínas de Xenopus , Cálcio/metabolismo , Diferenciação Celular , Cílios/metabolismo , Proteínas Hedgehog/metabolismo , Tubo Neural/metabolismo , Neurogênese/fisiologia , Xenopus laevis , Animais
9.
J Biol Chem ; 300(9): 107642, 2024 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-39122009

RESUMO

Our previous studies determined that elevating SOX2 in a wide range of tumor cells leads to a reversible state of tumor growth arrest. Efforts to understand how tumor cell growth is inhibited led to the discovery of a SOX2:MYC axis that is responsible for downregulating c-MYC (MYC) when SOX2 is elevated. Although we had determined that elevating SOX2 downregulates MYC transcription, the mechanism responsible was not determined. Given the challenges of targeting MYC clinically, we set out to identify how elevating SOX2 downregulates MYC transcription. In this study, we focused on the MYC promoter region and an upstream region of the MYC locus that contains a MYC super-enhancer encompassing five MYC enhancers and which is associated with several cancers. Here we report that BRD4 and p300 associate with each of the MYC enhancers in the upstream MYC super-enhancer as well as the MYC promoter region and that elevating SOX2 decreases the recruitment of BRD4 and p300 to these sites. Additionally, we determined that elevating SOX2 leads to increases in the association of SOX2 and H3K27me3 within the MYC super-enhancer and the promoter region of MYC. Importantly, we conclude that the increases in SOX2 within the MYC super-enhancer precipitate a cascade of events that culminates in the repression of MYC transcription. Together, our studies identify a novel molecular mechanism able to regulate MYC transcription in two distinctly different tumor types and provide new mechanistic insights into the molecular interrelationships between two master regulators, SOX2 and MYC, widely involved in multiple cancers.

10.
Development ; 149(14)2022 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-35861233

RESUMO

The transcription factor SOX2 is a vital regulator of stem cell activity in various developing and adult tissues. Mounting evidence has demonstrated the importance of SOX2 in regulating the induction and maintenance of stemness as well as in controlling cell proliferation, lineage decisions and differentiation. Recent studies have revealed that the ability of SOX2 to regulate these stem cell features involves its function as a pioneer factor, with the capacity to target nucleosomal DNA, modulate chromatin accessibility and prepare silent genes for subsequent activation. Moreover, although SOX2 binds to similar DNA motifs in different stem cells, its multifaceted and cell type-specific functions are reliant on context-dependent features. These cell type-specific properties include variations in partner factor availability and SOX2 protein expression levels. In this Primer, we discuss recent findings that have increased our understanding of how SOX2 executes its versatile functions as a master regulator of stem cell activities.


Assuntos
Nucleossomos , Fatores de Transcrição SOXB1 , Diferenciação Celular/genética , Proliferação de Células/genética , Cromatina , Fatores de Transcrição SOXB1/genética , Fatores de Transcrição SOXB1/metabolismo
11.
FASEB J ; 38(4): e23492, 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38363564

RESUMO

Lineage specification and X chromosome dosage compensation are two crucial biological processes that occur during preimplantation embryonic development. Although extensively studied in mice, the timing and regulation of these processes remain elusive in other species, including humans. Previous studies have suggested conserved principles of human and bovine early development. This study aims to provide fundamental insights into these programs and the regulation using a bovine embryo model by employing single-cell transcriptomics and genome editing approaches. The study analyzes the transcriptomes of 286 individual cells and reveals that bovine trophectoderm/inner cell mass transcriptomes diverge at the early blastocyst stage, after cavitation but before blastocyst expansion. The study also identifies transcriptomic markers and provides the timing of lineage specification events in the bovine embryo. Importantly, we find that SOX2 is required for the first cell decision program in bovine embryos. Moreover, the study shows the occurrence of X chromosome dosage compensation from morula to late blastocyst and reveals that this compensation results from downregulation of X-linked genes in female embryonic cells. The transcriptional atlas generated by this study is expected to be widely useful in improving our understanding of mammalian early embryo development.


Assuntos
Blastocisto , Análise da Expressão Gênica de Célula Única , Gravidez , Bovinos , Animais , Feminino , Humanos , Camundongos , Embrião de Mamíferos , Desenvolvimento Embrionário/genética , Cromossomo X/genética , Regulação da Expressão Gênica no Desenvolvimento , Linhagem da Célula/genética , Mamíferos
12.
Mol Cell ; 65(4): 581-582, 2017 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-28212744

RESUMO

In this issue of Molecular Cell, Liu and Kraus (2017) demonstrate that the pioneer transcription factor Sox2 requires PARP1 to bind to a subset of its recognition motifs, which are located within nucleosomes across the genome.


Assuntos
Nucleossomos , Fatores de Transcrição SOXB1/genética , Genoma
13.
Mol Cell ; 65(4): 589-603.e9, 2017 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-28212747

RESUMO

Pioneer transcription factors (TFs) function as genomic first responders, binding to inaccessible regions of chromatin to promote enhancer formation. The mechanism by which pioneer TFs gain access to chromatin remains an important unanswered question. Here we show that PARP-1, a nucleosome-binding protein, cooperates with intrinsic properties of the pioneer TF Sox2 to facilitate its binding to intractable genomic loci in embryonic stem cells. These actions of PARP-1 occur independently of its poly(ADP-ribosyl) transferase activity. PARP-1-dependent Sox2-binding sites reside in euchromatic regions of the genome with relatively high nucleosome occupancy and low co-occupancy by other transcription factors. PARP-1 stabilizes Sox2 binding to nucleosomes at suboptimal sites through cooperative interactions on DNA. Our results define intrinsic and extrinsic features that determine Sox2 pioneer activity. The conditional pioneer activity observed with Sox2 at a subset of binding sites may be a key feature of other pioneer TFs operating at intractable genomic loci.


Assuntos
DNA/metabolismo , Células-Tronco Embrionárias/enzimologia , Eucromatina/enzimologia , Regulação da Expressão Gênica no Desenvolvimento , Loci Gênicos , Nucleossomos/enzimologia , Células-Tronco Pluripotentes/enzimologia , Poli(ADP-Ribose) Polimerase-1/metabolismo , Fatores de Transcrição SOXB1/metabolismo , Animais , Sítios de Ligação , Linhagem Celular , DNA/genética , Eucromatina/genética , Humanos , Camundongos , Nucleossomos/genética , Poli(ADP-Ribose) Polimerase-1/genética , Ligação Proteica , Fatores de Transcrição SOXB1/genética , Transdução de Sinais , Fatores de Tempo , Transfecção
14.
Dev Dyn ; 253(3): 312-332, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37776236

RESUMO

INTRODUCTION: Primary cilia play pivotal roles in the patterning and morphogenesis of a wide variety of organs during mammalian development. Here we examined murine foregut septation in the cobblestone mutant, a hypomorphic allele of the gene encoding the intraflagellar transport protein IFT88, a protein essential for normal cilia function. RESULTS: We reveal a crucial role for primary cilia in foregut division, since their dramatic decrease in cilia in both the foregut endoderm and mesenchyme of mutant embryos resulted in a proximal tracheoesophageal septation defects and in the formation of distal tracheo(broncho)esophageal fistulae similar to the most common congenital tracheoesophageal malformations in humans. Interestingly, the dorsoventral patterning determining the dorsal digestive and the ventral respiratory endoderm remained intact, whereas Hedgehog signaling was aberrantly activated. CONCLUSIONS: Our results demonstrate the cobblestone mutant to represent one of the very few mouse models that display both correct endodermal dorsoventral specification but defective compartmentalization of the proximal foregut. It stands exemplary for a tracheoesophageal ciliopathy, offering the possibility to elucidate the molecular mechanisms how primary cilia orchestrate the septation process. The plethora of malformations observed in the cobblestone embryo allow for a deeper insight into a putative link between primary cilia and human VATER/VACTERL syndromes.


Assuntos
Ciliopatias , Proteínas Hedgehog , Humanos , Animais , Camundongos , Proteínas Hedgehog/genética , Cílios , Alelos , Modelos Animais de Doenças , Mamíferos
15.
Semin Cancer Biol ; 88: 123-137, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36603792

RESUMO

Cancer Stem Cells (CSCs) are now considered the primary "seeds" for the onset, development, metastasis, and recurrence of tumors. Despite therapeutic breakthroughs, cancer remains the leading cause of death worldwide. This is because the tumor microenvironment contains a key population of cells known as CSCs, which promote tumor aggression. CSCs are self-renewing cells that aid tumor recurrence by promoting tumor growth and persisting in patients after many traditional cancer treatments. According to reports, numerous transcription factors (TF) play a key role in maintaining CSC pluripotency and its self-renewal property. The understanding of the functions, structures, and interactional dynamics of these transcription factors with DNA has modified the hypothesis, paving the way for novel transcription factor-targeted therapies. These TFs, which are crucial and are required by cancer cells, play a vital function in the etiology of human cancer. Such CSC TFs will help with gene expression profiling, which provides crucial data for predicting the prognosis of patients. To overcome anti-cancer medication resistance and completely eradicate cancer, a potent therapy combining TFs-based CSC targets with traditional chemotherapy may be developed. In order to develop therapies that could eliminate CSCs, we here concentrated on the effect of TFs and other components of signalling pathways on cancer stemness.


Assuntos
Recidiva Local de Neoplasia , Fatores de Transcrição , Humanos , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Recidiva Local de Neoplasia/patologia , Transdução de Sinais , Células-Tronco Neoplásicas/metabolismo , Microambiente Tumoral/genética
16.
J Biol Chem ; 299(3): 102996, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36764520

RESUMO

SOX2 and SOX15 are Sox family transcription factors enriched in embryonic stem cells (ESCs). The role of SOX2 in activating gene expression programs essential for stem cell self-renewal and acquisition of pluripotency during somatic cell reprogramming is well-documented. However, the contribution of SOX15 to these processes is unclear and often presumed redundant with SOX2 largely because overexpression of SOX15 can partially restore self-renewal in SOX2-deficient ESCs. Here, we show that SOX15 contributes to stem cell maintenance by cooperating with ESC-enriched transcriptional coactivators to ensure optimal expression of pluripotency-associated genes. We demonstrate that SOX15 depletion compromises reprogramming of fibroblasts to pluripotency which cannot be compensated by SOX2. Ectopic expression of SOX15 promotes the reversion of a postimplantation, epiblast stem cell state back to a preimplantation, ESC-like identity even though SOX2 is expressed in both cell states. We also uncover a role of SOX15 in lineage specification, by showing that loss of SOX15 leads to defects in commitment of ESCs to neural fates. SOX15 promotes neural differentiation by binding to and activating a previously uncharacterized distal enhancer of a key neurogenic regulator, Hes5. Together, these findings identify a multifaceted role of SOX15 in induction and maintenance of pluripotency and neural differentiation.


Assuntos
Regulação da Expressão Gênica , Fatores de Transcrição , Diferenciação Celular/genética , Células-Tronco Embrionárias/metabolismo , Fibroblastos/metabolismo , Fatores de Transcrição/metabolismo , Proteínas Repressoras/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo
17.
Hippocampus ; 2024 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-39166359

RESUMO

Estrone and estradiol differentially modulate neuroplasticity and cognition. How they influence the maturation of new neurons in the adult hippocampus, however, is not known. The present study assessed the effects of estrone and estradiol on the maturation timeline of neurogenesis in the dentate gyrus (DG) of ovariectomized (a model of surgical menopause) young adult Sprague-Dawley rats using daily subcutaneous injections of 17ß-estradiol, estrone or vehicle. Rats were injected with a DNA synthesis marker, 5-bromo-2-deoxyuridine (BrdU), and were perfused 1, 2, or 3 weeks after BrdU injection and daily hormone treatment. Brains were sectioned and processed for various markers including: sex-determining region Y-box 2 (Sox2), glial fibrillary acidic protein (GFAP), antigen kiel 67 (Ki67), doublecortin (DCX), and neuronal nuclei (NeuN). Immunofluorescent labeling or co-labelling of BrdU with Sox2 (progenitor cells), Sox2/GFAP (neural progenitor cells), Ki67 (cell proliferation), DCX (immature neurons), NeuN (mature neurons) was used to examine the trajectory and maturation of adult-born neurons over time. Estrogens had early (1 week of exposure) effects on different stages of neurogenesis (neural progenitor cells, cell proliferation and early maturation of new cells into neurons) but these effects were less pronounced after prolonged treatment. Estradiol enhanced, whereas estrone reduced cell proliferation after 1 week but not after longer exposure to either estrogen. Both estrogens increased the density of immature neurons (BrdU/DCX-ir) after 1 week of exposure compared to vehicle treatment but this increased density was not sustained over longer durations of treatments to estrogens, suggesting that the enhancing effects of estrogens on neurogenesis were short-lived. Longer duration post-ovariectomy, without treatments with either of the estrogens, was associated with reduced neural progenitor cells in the DG. These results demonstrate that estrogens modulate several aspects of adult hippocampal neurogenesis differently in the short term, but may lose their ability to influence neurogenesis after long-term exposure. These findings have potential implications for treatments involving estrogens after surgical menopause.

18.
J Cell Sci ; 135(11)2022 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-35552718

RESUMO

Establishment of the pluripotency regulatory network in somatic cells by introducing four transcription factors [octamer binding transcription factor 4 (OCT4; also known as POU5F1), sex determining region Y (SRY)-box 2 (SOX2), Kruppel-like factor 4 (KLF4) and cellular myelocytomatosis (c-MYC)] provides a promising tool for cell-based therapies in regenerative medicine. Nevertheless, the mechanisms at play when generating induced pluripotent stem cells from somatic cells are only partly understood. Here, we show that the RNA-specific N6-methyladenosine (m6A) demethylase ALKBH5 regulates somatic cell reprogramming in a stage-specific manner through its catalytic activity. Knockdown or knockout of Alkbh5 in the early reprogramming phase impairs reprogramming efficiency by reducing the proliferation rate through arresting the cells at G2/M phase and decreasing the upregulation of epithelial markers. On the other hand, ALKBH5 overexpression at the early reprogramming phase has no significant impact on reprogramming efficiency, whereas overexpression at the late phase enhances reprogramming by stabilizing Nanog transcripts, resulting in upregulated Nanog expression. Our study provides mechanistic insight into the crucial dynamic role of ALKBH5, mediated through its catalytic activity, in regulating somatic cell reprogramming at the post-transcriptional level. This article has an associated First Person interview with the first author of the paper.


Assuntos
Reprogramação Celular , Células-Tronco Pluripotentes Induzidas , Homólogo AlkB 5 da RNA Desmetilase/genética , Homólogo AlkB 5 da RNA Desmetilase/metabolismo , Diferenciação Celular/fisiologia , Reprogramação Celular/genética , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Fatores de Transcrição Kruppel-Like/metabolismo , Fator 3 de Transcrição de Octâmero/genética , Fatores de Transcrição SOXB1/genética
19.
Gastroenterology ; 164(7): 1119-1136.e12, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-36740200

RESUMO

BACKGROUND & AIMS: Transformation of stem/progenitor cells has been associated with tumorigenesis in multiple tissues, but stem cells in the stomach have been hard to localize. We therefore aimed to use a combination of several markers to better target oncogenes to gastric stem cells and understand their behavior in the initial stages of gastric tumorigenesis. METHODS: Mouse models of gastric metaplasia and cancer by targeting stem/progenitor cells were generated and analyzed with techniques including reanalysis of single-cell RNA sequencing and immunostaining. Gastric cancer cell organoids were genetically manipulated with clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) for functional studies. Cell division was determined by bromodeoxyuridine-chasing assay and the assessment of the orientation of the mitotic spindles. Gastric tissues from patients were examined by histopathology and immunostaining. RESULTS: Oncogenic insults lead to expansion of SOX9+ progenitor cells in the mouse stomach. Genetic lineage tracing and organoid culture studies show that SOX9+ gastric epithelial cells overlap with SOX2+ progenitors and include stem cells that can self-renew and differentiate to generate all gastric epithelial cells. Moreover, oncogenic targeting of SOX9+SOX2+ cells leads to invasive gastric cancer in our novel mouse model (Sox2-CreERT;Sox9-loxp(66)-rtTA-T2A-Flpo-IRES-loxp(71);Kras(Frt-STOP-Frt-G12D);P53R172H), which combines Cre-loxp and Flippase-Frt genetic recombination systems. Sox9 deletion impedes the expansion of gastric progenitor cells and blocks neoplasia after Kras activation. Although Sox9 is not required for maintaining tissue homeostasis where asymmetric division predominates, loss of Sox9 in the setting of Kras activation leads to reduced symmetric cell division and effectively attenuates the Kras-dependent expansion of stem/progenitor cells. Similarly, Sox9 deletion in gastric cancer organoids reduces symmetric cell division, organoid number, and organoid size. In patients with gastric cancer, high levels of SOX9 are associated with recurrence and poor prognosis. CONCLUSION: SOX9 marks gastric stem cells and modulates biased symmetric cell division, which appears to be required for the malignant transformation of gastric stem cells.


Assuntos
Proteínas Proto-Oncogênicas p21(ras) , Neoplasias Gástricas , Camundongos , Animais , Proteínas Proto-Oncogênicas p21(ras)/genética , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Neoplasias Gástricas/patologia , Proliferação de Células , Transformação Celular Neoplásica/patologia , Carcinogênese/patologia , Divisão Celular , Células-Tronco/metabolismo
20.
J Bioenerg Biomembr ; 56(3): 323-332, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38441855

RESUMO

Non-small cell lung cancer (NSCLC) is an aggressive and rapidly expanding lung cancer. Abnormal upregulation or knockdown of PDIA6 expression can predict poor prognosis in various cancers. This study aimed to investigate the biological function of PDIA6 in NSCLC. SOX2 and PDIA6 expression in NSCLC tissues and regulatory relationship between them were analyzed using bioinformatics. GSEA was performed on the enrichment pathway of PDIA6. qRT-PCR was utilized to examine expression of SOX2 and PDIA6 in NSCLC tissues and cells, and dual-luciferase reporter assay and ChIP experiments were performed to validate their regulatory relationship. CCK-8 experiment was conducted to assess cell viability, western blot was to examine levels of stem cell markers and proteins related to aerobic glycolysis pathway in cells. Cell sphere formation assay was used to evaluate efficiency of cell sphere formation. Reagent kits were used to measure glycolysis levels and glycolysis products. High expression of PDIA6 in NSCLC was linked to aerobic glycolysis. Knockdown of PDIA6 reduced cell viability, expression of stem cell surface markers, and cell sphere formation efficiency in NSCLC. Overexpression of PDIA6 could enhance cell viability and promote aerobic glycolysis, but the addition of 2-DG could reverse this result. Bioinformatics predicted the existence of upstream transcription factor SOX2 for PDIA6, and SOX2 was significantly upregulated in NSCLC, and they had a binding relationship. Further experiments revealed that PDIA6 overexpression restored repressive effect of knocking down SOX2 on aerobic glycolysis and cell stemness. This work revealed that the SOX2/PDIA6 axis mediated aerobic glycolysis to promote NSCLC cell stemness, providing new therapeutic strategies for NSCLC.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Isomerases de Dissulfetos de Proteínas , Fatores de Transcrição SOXB1 , Humanos , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular Tumoral , Glicólise/fisiologia , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Isomerases de Dissulfetos de Proteínas/metabolismo , Fatores de Transcrição SOXB1/metabolismo
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