RESUMEN
Aberrant activation of GLI transcription factors has been implicated in the pathogenesis of different tumor types including pancreatic ductal adenocarcinoma. However, the mechanistic link with established drivers of this disease remains in part elusive. In this study, using a new genetically engineered mouse model overexpressing constitutively active mouse form of GLI2 and a combination of genome-wide assays, we provide evidence of a novel mechanism underlying the interplay between KRAS, a major driver of pancreatic ductal adenocarcinoma development, and GLI2 to control oncogenic gene expression. These mice, also expressing KrasG12D, show significantly reduced median survival rate and accelerated tumorigenesis compared with the KrasG12D only expressing mice. Analysis of the mechanism using RNA sequencing demonstrate higher levels of GLI2 targets, particularly tumor growth-promoting genes, including Ccnd1, N-Myc, and Bcl2, in KrasG12D mutant cells. Furthermore, chromatin immunoprecipitation sequencing studies showed that in these cells KrasG12D increases the levels of trimethylation of lysine 4 of the histone 3 (H3K4me3) at the promoter of GLI2 targets without affecting significantly the levels of other major active chromatin marks. Importantly, Gli2 knockdown reduces H3K4me3 enrichment and gene expression induced by mutant Kras. In summary, we demonstrate that Gli2 plays a significant role in pancreatic carcinogenesis by acting as a downstream effector of KrasG12D to control gene expression.
Asunto(s)
Carcinoma Ductal Pancreático , Regulación Neoplásica de la Expresión Génica , Neoplasias Pancreáticas , Proteínas Proto-Oncogénicas p21(ras) , Proteína Gli2 con Dedos de Zinc , Animales , Humanos , Ratones , Carcinogénesis , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/patología , Carcinoma Ductal Pancreático/metabolismo , Línea Celular Tumoral , Histonas/metabolismo , Histonas/genética , Ratones Transgénicos , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patología , Neoplasias Pancreáticas/metabolismo , Regiones Promotoras Genéticas/genética , Proteínas Proto-Oncogénicas p21(ras)/genética , Proteínas Proto-Oncogénicas p21(ras)/metabolismo , Transcripción Genética , Proteína Gli2 con Dedos de Zinc/genética , Proteína Gli2 con Dedos de Zinc/metabolismoRESUMEN
Myeloid neoplasms are clonal hematopoietic stem cell disorders driven by the sequential acquisition of recurrent genetic lesions. Truncating mutations in the chromatin remodeler ASXL1 (ASXL1MT) are associated with a high-risk disease phenotype with increased proliferation, epigenetic therapeutic resistance, and poor survival outcomes. We performed a multi-omics interrogation to define gene expression and chromatin remodeling associated with ASXL1MT in chronic myelomonocytic leukemia (CMML). ASXL1MT are associated with a loss of repressive histone methylation and increase in permissive histone methylation and acetylation in promoter regions. ASXL1MT are further associated with de novo accessibility of distal enhancers binding ETS transcription factors, targeting important leukemogenic driver genes. Chromatin remodeling of promoters and enhancers is strongly associated with gene expression and heterogenous among overexpressed genes. These results provide a comprehensive map of the transcriptome and chromatin landscape of ASXL1MT CMML, forming an important framework for the development of novel therapeutic strategies targeting oncogenic cis interactions.
Asunto(s)
Leucemia Mielomonocítica Crónica , Epigénesis Genética , Expresión Génica , Humanos , Leucemia Mielomonocítica Crónica/genética , Leucemia Mielomonocítica Crónica/patología , Mutación , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
Pancreatitis is a debilitating disease involving inflammation and fibrosis of the exocrine pancreas. Recurrent or chronic forms of pancreatitis are a significant risk factor for pancreatic ductal adenocarcinoma. While genetic factors have been identified for both pathologies, environmental stresses play a large role in their etiology. All cells have adapted mechanisms to handle acute environmental stress that alters energy demands. A common pathway involved in the stress response involves endoplasmic reticulum stress and the unfolded protein response (UPR). While rapidly activated by many external stressors, in the pancreas the UPR plays a fundamental biological role, likely due to the high protein demands in acinar cells. Despite this, increased UPR activity is observed in response to acute injury or following exposure to risk factors associated with pancreatitis and pancreatic cancer. Studies in animal and cell cultures models show the importance of affecting the UPR in the context of both diseases, and inhibitors have been developed for several specific mediators of the UPR. Given the importance of the UPR to normal acinar cell function, efforts to affect the UPR in the context of disease must be able to specifically target pathology vs. physiology. In this review, we highlight the importance of the UPR to normal and pathological conditions of the exocrine pancreas. We discuss recent studies suggesting the UPR may be involved in the initiation and progression of pancreatitis and PDAC, as well as contributing to chemoresistance that occurs in pancreatic cancer. Finally, we discuss the potential of targeting the UPR for treatment.
Asunto(s)
Carcinoma Ductal Pancreático , Estrés del Retículo Endoplásmico/efectos de los fármacos , Neoplasias Pancreáticas/terapia , Pancreatitis , Respuesta de Proteína Desplegada , Factor de Transcripción Activador 6/genética , Factor de Transcripción Activador 6/metabolismo , Animales , Carcinoma Ductal Pancreático/tratamiento farmacológico , Carcinoma Ductal Pancreático/genética , Estrés del Retículo Endoplásmico/genética , Endorribonucleasas , Recurrencia Local de Neoplasia , Neoplasias Pancreáticas/tratamiento farmacológico , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/metabolismo , Pancreatitis/tratamiento farmacológico , Pancreatitis/genética , Proteínas Serina-Treonina Quinasas , eIF-2 Quinasa , Neoplasias PancreáticasRESUMEN
One hundred years have passed since the discovery of insulin-an achievement that transformed diabetes from a fatal illness into a manageable chronic condition. The decades since that momentous achievement have brought ever more rapid innovation and advancement in diabetes research and clinical care. To celebrate the important work of the past century and help to chart a course for its continuation into the next, the Canadian Institutes of Health Research's Institute of Nutrition, Metabolism and Diabetes and the U.S. National Institutes of Health's National Institute of Diabetes and Digestive and Kidney Diseases recently held a joint international symposium, bringing together a cohort of researchers with diverse interests and backgrounds from both countries and beyond to discuss their collective quest to better understand the heterogeneity of diabetes and thus gain insights to inform new directions in diabetes treatment and prevention. This article summarizes the proceedings of that symposium, which spanned cutting-edge research into various aspects of islet biology, the heterogeneity of diabetic phenotypes, and the current state of and future prospects for precision medicine in diabetes.
Asunto(s)
Diabetes Mellitus , Medicina de Precisión , Canadá , Diabetes Mellitus/terapia , Humanos , National Institute of Diabetes and Digestive and Kidney Diseases (U.S.) , National Institutes of Health (U.S.) , Fenotipo , Estados UnidosRESUMEN
One hundred years have passed since the discovery of insulin-an achievement that transformed diabetes from a fatal illness into a manageable chronic condition. The decades since that momentous achievement have brought ever more rapid innovation and advancement in diabetes research and clinical care. To celebrate the important work of the past century and help to chart a course for its continuation into the next, the Canadian Institutes of Health Research's Institute of Nutrition, Metabolism and Diabetes and the U.S. National Institutes of Health's National Institute of Diabetes and Digestive and Kidney Diseases recently held a joint international symposium, bringing together a cohort of researchers with diverse interests and backgrounds from both countries and beyond to discuss their collective quest to better understand the heterogeneity of diabetes and thus gain insights to inform new directions in diabetes treatment and prevention. This article summarizes the proceedings of that symposium, which spanned cutting-edge research into various aspects of islet biology, the heterogeneity of diabetic phenotypes, and the current state of and future prospects for precision medicine in diabetes.
RESUMEN
One hundred years have passed since the discovery of insulin-an achievement that transformed diabetes from a fatal illness into a manageable chronic condition. The decades since that momentous achievement have brought ever more rapid innovation and advancement in diabetes research and clinical care. To celebrate the important work of the past century and help to chart a course for its continuation into the next, the Canadian Institutes of Health Research's Institute of Nutrition, Metabolism and Diabetes and the U.S. National Institutes of Health's National Institute of Diabetes and Digestive and Kidney Diseases recently held a joint international symposium, bringing together a cohort of researchers with diverse interests and backgrounds from both countries and beyond to discuss their collective quest to better understand the heterogeneity of diabetes and thus gain insights to inform new directions in diabetes treatment and prevention. This article summarizes the proceedings of that symposium, which spanned cutting-edge research into various aspects of islet biology, the heterogeneity of diabetic phenotypes, and the current state of and future prospects for precision medicine in diabetes.
RESUMEN
One hundred years have passed since the discovery of insulin-an achievement that transformed diabetes from a fatal illness into a manageable chronic condition. The decades since that momentous achievement have brought ever more rapid innovation and advancement in diabetes research and clinical care. To celebrate the important work of the past century and help to chart a course for its continuation into the next, the Canadian Institutes of Health Research's Institute of Nutrition, Metabolism and Diabetes and the U.S. National Institutes of Health's National Institute of Diabetes and Digestive and Kidney Diseases recently held a joint international symposium, bringing together a cohort of researchers with diverse interests and backgrounds from both countries and beyond to discuss their collective quest to better understand the heterogeneity of diabetes and thus gain insights to inform new directions in diabetes treatment and prevention. This article summarizes the proceedings of that symposium, which spanned cutting-edge research into various aspects of islet biology, the heterogeneity of diabetic phenotypes, and the current state of and future prospects for precision medicine in diabetes.
Asunto(s)
Diabetes Mellitus , Medicina de Precisión , Canadá/epidemiología , Diabetes Mellitus/terapia , Humanos , National Institute of Diabetes and Digestive and Kidney Diseases (U.S.) , National Institutes of Health (U.S.) , Fenotipo , Estados UnidosRESUMEN
The unfolded protein response (UPR) is activated in pancreatic pathologies and suggested as a target for therapeutic intervention. In this study, we examined activating transcription factor 3 (ATF3), a mediator of the UPR that promotes acinar-to-ductal metaplasia (ADM) in response to pancreatic injury. Since ADM is an initial step in the progression to pancreatic ductal adenocarcinoma (PDAC), we hypothesized that ATF3 is required for initiation and progression of PDAC. We generated mice carrying a germline mutation of Atf3 (Atf3-/-) combined with acinar-specific induction of oncogenic KRAS (Ptf1acreERT/+KrasG12D/+). Atf3-/- mice with (termed APK) and without KRASG12D were exposed to cerulein-induced pancreatitis. In response to recurrent pancreatitis, Atf3-/- mice showed decreased ADM and enhanced regeneration based on morphological and biochemical analysis. Similarly, an absence of ATF3 reduced spontaneous pancreatic intraepithelial neoplasia (PanIN) formation and PDAC in Ptf1acreERT/+KrasG12D/+ mice. In response to injury, KRASG12D bypassed the requirement for ATF3 with a dramatic loss in acinar tissue and PanIN formation observed regardless of ATF3 status. Compared to Ptf1acreERT/+KrasG12D/+ mice, APK mice exhibited a significant decrease in pancreatic and total body weight, did not progress through to PDAC, and showed altered pancreatic fibrosis and immune cell infiltration. These findings suggest a complex, multifaceted role for ATF3 in pancreatic cancer pathology.
Asunto(s)
Factor de Transcripción Activador 3 , Células Acinares , Animales , Ceruletida , Humanos , Ratones , Neoplasias Pancreáticas , Proteínas Proto-Oncogénicas p21(ras) , Neoplasias PancreáticasRESUMEN
Pancreatic cancer remains among the deadliest forms of cancer with a 5 year survival rate less than 10%. With increasing numbers being observed, there is an urgent need to elucidate the pathogenesis of pancreatic cancer. While both contribute to disease progression, neither genetic nor environmental factors completely explain susceptibility or pathogenesis. Defining the links between genetic and environmental events represents an opportunity to understand the pathogenesis of pancreatic cancer. Epigenetics, the study of mitotically heritable changes in genome function without a change in nucleotide sequence, is an emerging field of research in pancreatic cancer. The main epigenetic mechanisms include DNA methylation, histone modifications and RNA interference, all of which are altered by changes to the environment. Epigenetic mechanisms are being investigated to clarify the underlying pathogenesis of pancreatic cancer including an increasing number of studies examining the role as possible diagnostic and prognostic biomarkers. These mechanisms also provide targets for promising new therapeutic approaches for this devastating malignancy.
RESUMEN
Acinar cell exocytosis requires spatiotemporal Ca2+ signals regulated through endoplasmic reticulum (ER) stores, Ca2+ATPases, and store-operated Ca2+ entry (SOCE). The secretory pathway Ca2+ATPase 2 (SPCA2) interacts with Orai1, which is involved in SOCE and store independent Ca2+ entry (SICE). However, in the pancreas, only a C-terminally truncated form of SPCA2 (termed SPAC2C) exists. The goal of this study was to determine if SPCA2C effects Ca2+ homeostasis in a similar fashion to the full-length SPCA2. Using epitope-tagged SPCA2C (SPCA2CFLAG) expressed in HEK293A cells and Fura2 imaging, cytosolic [Ca2+] was examined during SICE, SOCE and secretagogue-stimulated signaling. Exogenous SPCA2C expression increased resting cytosolic [Ca2+], Ca2+ release in response to carbachol, ER Ca2+ stores, and store-mediated and independent Ca2+ influx. Co-IP detected Orai1-SPCA2C interaction, which was altered by co-expression of STIM1. Importantly, SPCA2C's effects on store-mediated Ca2+ entry were independent of Orai1. These findings indicate SPCA2C influences Ca2+ homeostasis through multiple mechanisms, some of which are independent of Orai1, suggesting novel and possibly cell-specific Ca2+ regulation.
Asunto(s)
Señalización del Calcio/fisiología , ATPasas Transportadoras de Calcio/fisiología , Calcio/metabolismo , Páncreas/metabolismo , Canales de Calcio/metabolismo , Retículo Endoplásmico/metabolismo , Células HEK293 , Homeostasis , Humanos , Proteína ORAI2/genética , Proteína ORAI2/metabolismo , Especificidad de Órganos/genética , Isoformas de Proteínas/fisiología , Vías Secretoras/fisiologíaRESUMEN
The enzyme enhancer of zeste homologue 2 (EZH2) plays a catalytic role in histone methylation (H3K27me3), one of the epigenetic modifications that is dysregulated in cancer. The development of a positron emission tomography (PET) imaging agent targeting EZH2 has the potential to provide a method of stratifying patients for epigenetic therapies. In this study, we designed and synthesized a series of fluoroethyl analogs based upon the structure of EZH2 inhibitors UNC1999 and EPZ6438. Among the candidate compounds, 20b exhibited a high binding affinity to EZH2 (IC50 = 6 nM) with selectivity versus EZH1 (IC50 = 200 nM) by SAM competition assay, and furthermore, EZH2 inhibition was demonstrated in the pancreatic cancer cell line PANC-1 (IC50 = 9.8 nM). [18F]20b was synthesized successfully and showed 5-fold higher uptake in PANC-1 cells than in MCF-7 cells. MicroPET imaging in a PANC-1 cell xenograft mouse model indicates that [18F]20b has specific binding to EZH2, which was identified by ex vivo Western blot analysis of the tumor tissue.
RESUMEN
Background: Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer death in North America, accounting for >30,000 deaths annually. Although somatic activating mutations in KRAS appear in 97% of PDAC patients, additional factors are required to initiate PDAC. Because mutations in genes encoding chromatin remodelling proteins have been implicated in KRAS-mediated PDAC, we investigated whether loss of chromatin remodeler É-thalassemia, mental-retardation, X-linked (ATRX) affects oncogenic KRAS's ability to promote PDAC. ATRX affects DNA replication, repair, and gene expression and is implicated in other cancers including glioblastomas and pancreatic neuroendocrine tumors. The hypothesis was that deletion of Atrx in pancreatic acinar cells will increase susceptibility to injury and oncogenic KRAS. Methods: Mice allowing conditional loss of Atrx within pancreatic acinar cells were examined after induction of recurrent cerulein-induced pancreatitis or oncogenic KRAS (KRASG12D ). Histologic, biochemical, and molecular analysis examined pancreatic pathologies up to 2 months after induction of Atrx deletion. Results: Mice lacking Atrx showed more progressive damage, inflammation, and acinar-to-duct cell metaplasia in response to injury relative to wild-type mice. In combination with KRASG12D, Atrx-deficient acinar cells showed increased fibrosis, inflammation, progression to acinar-to-duct cell metaplasia, and pre-cancerous lesions relative to mice expressing only KRASG12D. This sensitivity appears only in female mice, mimicking a significant prevalence of ATRX mutations in human female PDAC patients. Conclusions: Our results indicate the absence of ATRX increases sensitivity to injury and oncogenic KRAS only in female mice. This is an instance of a sex-specific mutation that enhances oncogenic KRAS's ability to promote pancreatic intraepithelial lesion formation.
Asunto(s)
Oncogenes , Páncreas/lesiones , Proteínas Proto-Oncogénicas p21(ras)/metabolismo , Proteína Nuclear Ligada al Cromosoma X/deficiencia , Células Acinares/metabolismo , Células Acinares/patología , Animales , Apoptosis , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Análisis Mutacional de ADN , Femenino , Eliminación de Gen , Masculino , Ratones , Páncreas/patología , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patología , Lesiones Precancerosas/metabolismo , Lesiones Precancerosas/patología , Proteína Nuclear Ligada al Cromosoma X/metabolismo , Neoplasias PancreáticasRESUMEN
International experts gathered at the Mayo Clinic (Rochester MN, USA) on February 27th-28th, 2017 for a meeting entitled 'Basic and Translational Facets of the Epigenetics of GI Diseases'. This workshop summarized recent advances on the role of epigenetics in the pathobiology of gastrointestinal (GI) diseases. Highlights of the meeting included recent advances on the involvement of different epigenetic mechanisms in malignant and nonmalignant GI disorders and the epigenetic heterogeneity exhibited in these diseases. The translational value of epigenetic drugs, as well as the current and future use of epigenetic changes (i.e., DNA methylation patterns) as biomarkers for early detection tools or disease stratification were also important topics of discussion.
Asunto(s)
Epigénesis Genética , Enfermedades Gastrointestinales/genética , Metilación de ADN , Heterogeneidad Genética , Marcadores Genéticos , Humanos , Investigación Biomédica TraslacionalRESUMEN
Pancreatitis is a debilitating disease of the exocrine pancreas that, under chronic conditions, is a major susceptibility factor for pancreatic ductal adenocarcinoma (PDAC). Although down-regulation of genes that promote the mature acinar cell fate is required to reduce injury associated with pancreatitis, the factors that promote this repression are unknown. Activating transcription factor 3 (ATF3) is a key mediator of the unfolded protein response, a pathway rapidly activated during pancreatic insult. Using chromatin immunoprecipitation followed by next-generation sequencing, we show that ATF3 is bound to the transcriptional regulatory regions of >30% of differentially expressed genes during the initiation of pancreatitis. Of importance, ATF3-dependent regulation of these genes was observed only upon induction of pancreatitis, with pathways involved in inflammation, acinar cell differentiation, and cell junctions being specifically targeted. Characterizing expression of transcription factors that affect acinar cell differentiation suggested that acinar cells lacking ATF3 maintain a mature cell phenotype during pancreatitis, a finding supported by maintenance of junctional proteins and polarity markers. As a result, Atf3-/- pancreatic tissue displayed increased tissue damage and inflammatory cell infiltration at early time points during injury but, at later time points, showed reduced acinar-to-duct cell metaplasia. Thus our results reveal a critical role for ATF3 as a key regulator of the acinar cell transcriptional response during injury and may provide a link between chronic pancreatitis and PDAC.
Asunto(s)
Células Acinares/metabolismo , Factor de Transcripción Activador 3/metabolismo , Pancreatitis/metabolismo , Pancreatitis/patología , Células Acinares/citología , Factor de Transcripción Activador 3/genética , Animales , Carcinoma Ductal Pancreático/metabolismo , Carcinoma Ductal Pancreático/patología , Diferenciación Celular/fisiología , Ceruletida , Regulación hacia Abajo , Masculino , Ratones , Ratones Noqueados , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patología , Pancreatitis/inducido químicamente , Fenotipo , Neoplasias PancreáticasRESUMEN
Organic anion-transporting polypeptides (OATPs) are membrane proteins that mediate cellular uptake of structurally diverse endogenous and exogenous compounds, including bile salts, thyroid and sex hormones, pharmacological agents, and toxins. Roles of OATPs in human liver are well established. Our recent report suggested the presence of the hepatic transporter OATP1B3 in human ß cells. The aim of this study was to better characterize cellular localization and interindividual variation in OATP1B3 expression in human adult islets as a function of age, sex, and pancreatic disease, and to assess the expression of other OATPs. High transcript levels of OATP1B3, OATP2B1, OATP1A2, but not OATP1B1 were observed in isolated human adult islets. While OATP1B3 protein expression was variable, the carrier co-localized more frequently with glucagon-positive α cells than insulin-positive ß cells in islets of normal pancreatic tissues from ten subjects using dual immunostaining. Moreover, OATP1B3 co-staining with endocrine cells was two- to three-fold higher in older (≥60 years) than younger (<60 years) subjects. In comparison, in a subset of three individuals, OATP2B1 was primarily found in ß cells, suggesting a distinct expression pattern for OATP1B3 and OATP2B1 in islets. Abundant OATP1B3 staining was also observed in islet as well as ductal cells of diseased tissues of patients with pancreatitis or pancreatic adenocarcinoma. Considering the abundance of key OATP carriers in ß and α cells, potential implications of OATP transport in islet cell function may be suggested. Future studies are needed to gain insights into their specific endocrine roles as well as pharmacological relevance.
Asunto(s)
Islotes Pancreáticos/metabolismo , Transportadores de Anión Orgánico/genética , Miembro 1B3 de la Familia de los Transportadores de Solutos de Aniones Orgánicos/genética , Adulto , Humanos , Islotes Pancreáticos/química , Islotes Pancreáticos/citología , Transportadores de Anión Orgánico/análisis , Transportadores de Anión Orgánico/metabolismo , ARN Mensajero/genética , Miembro 1B3 de la Familia de los Transportadores de Solutos de Aniones Orgánicos/análisis , Miembro 1B3 de la Familia de los Transportadores de Solutos de Aniones Orgánicos/metabolismoRESUMEN
Nonalcoholic fatty liver disease (NAFLD) alters drug response. We previously reported that NAFLD is associated with reduced in vivo CYP3A drug-metabolism activity and hepatic CYP3A4 expression in humans as well as mouse and human hepatoma models of the disease. Here, we investigated the role of the lipid- and glucose-modulating hormone fibroblast growth factor 21 (FGF21) in the molecular mechanism regulating CYP3A4 expression in NAFLD. In human subjects, mouse and cellular NAFLD models with lower CYP3A4 expression, circulating FGF21, or hepatic FGF21 mRNA levels were elevated. Administration of recombinant FGF21 or transient hepatic overexpression of FGF21 resulted in reduced liver CYP3A4 luciferase reporter activity in mice and decreased CYP3A4 mRNA expression and activity in cultured Huh7 hepatoma cells. Blocking canonical FGF21 signaling by pharmacological inhibition of MEK1 kinase in Huh7 cells caused de-repression of CYP3A4 mRNA expression with FGF21 treatment. Mice with high-fat diet-induced simple hepatic steatosis and lipid-loaded Huh7 cells had reduced nuclear localization of the pregnane X receptor (PXR), a key transcriptional regulator of CYP3A4 Furthermore, decreased nuclear PXR was observed in mouse liver and Huh7 cells after FGF21 treatment or FGF21 overexpression. Decreased PXR binding to the CYP3A4 proximal promoter was found in FGF21-treated Huh7 cells. An FGF21-PXR signaling pathway may be involved in decreased hepatic CYP3A4 metabolic activity in NAFLD.
Asunto(s)
Citocromo P-450 CYP3A/genética , Regulación hacia Abajo , Factores de Crecimiento de Fibroblastos/metabolismo , Enfermedad del Hígado Graso no Alcohólico/enzimología , Enfermedad del Hígado Graso no Alcohólico/genética , Receptores de Esteroides/metabolismo , Transducción de Señal , Animales , Línea Celular Tumoral , Citocromo P-450 CYP3A/metabolismo , Modelos Animales de Enfermedad , Femenino , Factores de Crecimiento de Fibroblastos/administración & dosificación , Factores de Crecimiento de Fibroblastos/sangre , Factores de Crecimiento de Fibroblastos/genética , Glucuronidasa/metabolismo , Humanos , Proteínas Klotho , Hígado , Sistema de Señalización de MAP Quinasas , Ratones Endogámicos C57BL , Enfermedad del Hígado Graso no Alcohólico/sangre , Receptor X de Pregnano , Regiones Promotoras Genéticas/genética , Unión Proteica , Receptores de Factores de Crecimiento de Fibroblastos/metabolismo , Fracciones Subcelulares/metabolismo , Transcripción GenéticaRESUMEN
Proper regulation of cytosolic Ca(2+) is critical for pancreatic acinar cell function. Disruptions in normal Ca(2+) concentrations affect numerous cellular functions and are associated with pancreatitis. Membrane pumps and channels regulate cytosolic Ca(2+) homeostasis by promoting rapid Ca(2+) movement. Determining how expression of Ca(2+) modulators is regulated and the cellular alterations that occur upon changes in expression can provide insight into initiating events of pancreatitis. The goal of this study was to delineate the gene structure and regulation of a novel pancreas-specific isoform for Secretory Pathway Ca(2+) ATPase 2 (termed SPCA2C), which is encoded from the Atp2c2 gene. Using Next Generation Sequencing of RNA (RNA-seq), chromatin immunoprecipitation for epigenetic modifications and promoter-reporter assays, a novel transcriptional start site was identified that promotes expression of a transcript containing the last four exons of the Atp2c2 gene (Atp2c2c). This region was enriched for epigenetic marks and pancreatic transcription factors that promote gene activation. Promoter activity for regions upstream of the ATG codon in Atp2c2's 24th exon was observed in vitro but not in in vivo. Translation from this ATG encodes a protein aligned with the carboxy terminal of SPCA2. Functional analysis in HEK 293A cells indicates a unique role for SPCA2C in increasing cytosolic Ca(2+) . RNA analysis indicates that the decreased Atp2c2c expression observed early in experimental pancreatitis reflects a global molecular response of acinar cells to reduce cytosolic Ca(2+) levels. Combined, these results suggest SPCA2C affects Ca(2+) homeostasis in pancreatic acinar cells in a unique fashion relative to other Ca(2+) ATPases. J. Cell. Physiol. 231: 2768-2778, 2016. © 2016 Wiley Periodicals, Inc.
Asunto(s)
Células Acinares/metabolismo , ATPasas Transportadoras de Calcio/genética , Páncreas/patología , Sitio de Iniciación de la Transcripción , Transcripción Genética , Células Acinares/patología , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Calcio/metabolismo , ATPasas Transportadoras de Calcio/química , ATPasas Transportadoras de Calcio/metabolismo , Ceruletida , Epigénesis Genética , Exones/genética , Femenino , Genoma , Células HEK293 , Histonas/metabolismo , Humanos , Masculino , Ratones Endogámicos C57BL , Ratones Transgénicos , Pancreatitis/genética , Pancreatitis/patología , Regiones Promotoras Genéticas , ARN Mensajero/genética , ARN Mensajero/metabolismoRESUMEN
UNLABELLED: Osteoarthritis (OA) is a highly prevalent, disabling joint disease with no existing therapies to slow or halt its progression. Cartilage degeneration hallmarks OA pathogenesis, and pannexin 3 (Panx3), a member of a novel family of channel proteins, is upregulated during this process. The function of Panx3 remains poorly understood, but we consistently observed a strong increase in Panx3 immunostaining in OA lesions in both mice and humans. Here, we developed and characterized the first global and conditional Panx3 knockout mice to investigate the role of Panx3 in OA. Interestingly, global Panx3 deletion produced no overt phenotype and had no obvious effect on early skeletal development. Mice lacking Panx3 specifically in the cartilage and global Panx3 knockout mice were markedly resistant to the development of OA following destabilization of medial meniscus surgery. These data indicate a specific catabolic role of Panx3 in articular cartilage and identify Panx3 as a potential therapeutic target for OA. Lastly, while Panx1 has been linked to over a dozen human pathologies, this is the first in vivo evidence for a role of Panx3 in disease. KEY MESSAGE: Panx3 is localized to cartilage lesions in mice and humans. Global Panx3 deletion does not result in any developmental abnormalities. Mice lacking Panx3 are resistant to the development of osteoarthritis. Panx3 is a novel therapeutic target for the treatment of osteoarthritis.
Asunto(s)
Cartílago Articular/patología , Conexinas/genética , Eliminación de Gen , Osteoartritis/genética , Osteoartritis/patología , Animales , Cartílago Articular/metabolismo , Línea Celular , Colágeno Tipo II/análisis , Colágeno Tipo II/metabolismo , Conexinas/análisis , Conexinas/metabolismo , Femenino , Humanos , Masculino , Metaloproteinasa 13 de la Matriz/análisis , Metaloproteinasa 13 de la Matriz/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Persona de Mediana Edad , Osteoartritis/etiología , Osteoartritis/metabolismoRESUMEN
Acinar cells of the pancreas produce the majority of enzymes required for digestion and make up >90% of the cells within the pancreas. Due to a common developmental origin and the plastic nature of the acinar cell phenotype, these cells have been identified as a possible source of ß cells as a therapeutic option for Type I diabetes. However, recent evidence indicates that acinar cells are the main source of pancreatic intraepithelial neoplasias (PanINs), the predecessor of pancreatic ductal adenocarcinoma (PDAC). The conversion of acinar cells to either ß cells or precursors to PDAC is dependent on reprogramming of the cells to a more primitive, progenitor-like phenotype, which involves changes in transcription factor expression and activity, and changes in their epigenetic program. This review will focus on the mechanisms that promote acinar cell reprogramming, as well as the factors that may affect these mechanisms.
Asunto(s)
Células Acinares/citología , Reprogramación Celular , Epigénesis Genética , Páncreas/citología , Células Acinares/metabolismo , Animales , Diferenciación Celular , Diabetes Mellitus Tipo 1/terapia , Humanos , Células Secretoras de Insulina/citología , Ratones , Páncreas/embriología , Enfermedades Pancreáticas , Conductos Pancreáticos/citología , Neoplasias Pancreáticas/etiologíaRESUMEN
The molecular mechanisms and metabolic pathways whereby the citrus flavonoid, naringenin, reduces dyslipidemia and improves glucose tolerance were investigated in C57BL6/J wild-type mice and fibroblast growth factor 21 (FGF21) null (Fgf21(-/-)) mice. FGF21 regulates energy homeostasis and the metabolic adaptation to fasting. One avenue of this regulation is through induction of peroxisome proliferator-activated receptor-γ coactivator-1α (Pgc1a), a regulator of hepatic fatty acid oxidation and ketogenesis. Because naringenin is a potent activator of hepatic FA oxidation, we hypothesized that induction of FGF21 might be an integral part of naringenin's mechanism of action. Furthermore, we predicted that FGF21 deficiency would potentiate high-fat diet (HFD)-induced metabolic dysregulation and compromise metabolic protection by naringenin. The absence of FGF21 exacerbated the response to a HFD. Interestingly, naringenin supplementation to the HFD robustly prevented obesity in both genotypes. Gene expression analysis suggested that naringenin was not primarily targeting fatty acid metabolism in white adipose tissue. Naringenin corrected hepatic triglyceride concentrations and normalized hepatic expression of Pgc1a, Cpt1a, and Srebf1c in both wild-type and Fgf21(-/-) mice. HFD-fed Fgf21(-/-) mice displayed greater muscle triglyceride deposition, hyperinsulinemia, and impaired glucose tolerance as compared with wild-type mice, confirming the role of FGF21 in insulin sensitivity; however, naringenin supplementation improved these metabolic parameters in both genotypes. We conclude that FGF21 deficiency exacerbates HFD-induced obesity, hepatic steatosis, and insulin resistance. Furthermore, FGF21 is not required for naringenin to protect mice from HFD-induced metabolic dysregulation. Collectively these studies support the concept that naringenin has potent lipid-lowering effects and may act as an insulin sensitizer in vivo.