RESUMEN
Heart development depends on coordinated proliferation and differentiation of cardiac progenitor cells (CPCs), but how the two processes are synchronized is not well understood. Here, we show that the secreted Bone Morphogenetic Protein (BMP) antagonist GREMLIN 2 (GREM2) is induced in CPCs shortly after cardiac mesoderm specification during differentiation of human pluripotent stem cells. GREM2 expression follows cardiac lineage differentiation independently of the differentiation method used, or the origin of the pluripotent stem cells, suggesting that GREM2 is linked to cardiogenesis. Addition of GREM2 protein strongly increases cardiomyocyte output compared to established procardiogenic differentiation methods. Our data show that inhibition of canonical BMP signaling by GREM2 is necessary to promote proliferation of CPCs. However, canonical BMP signaling inhibition alone is not sufficient to induce cardiac differentiation, which depends on subsequent JNK pathway activation specifically by GREM2. These findings may have broader implications in the design of approaches to orchestrate growth and differentiation of pluripotent stem cell-derived lineages that depend on precise regulation of BMP signaling.
Asunto(s)
Proteínas Morfogenéticas Óseas/genética , Diferenciación Celular/genética , Proliferación Celular/genética , Células Madre Pluripotentes Inducidas/metabolismo , Péptidos y Proteínas de Señalización Intercelular/genética , Células Madre/metabolismo , Proteínas Morfogenéticas Óseas/metabolismo , Proteínas Morfogenéticas Óseas/farmacología , Diferenciación Celular/efectos de los fármacos , Línea Celular , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Citocinas , Perfilación de la Expresión Génica , Regulación del Desarrollo de la Expresión Génica , Humanos , Células Madre Pluripotentes Inducidas/citología , Células Madre Pluripotentes Inducidas/efectos de los fármacos , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Péptidos y Proteínas de Señalización Intercelular/farmacología , Miocardio/citología , Miocardio/metabolismo , Miocitos Cardíacos/citología , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Organogénesis/genética , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética , Células Madre/citología , Células Madre/efectos de los fármacosRESUMEN
Protocols for generating populations of cardiomyocytes from pluripotent stem cells have been developed, but these generally yield cells of mixed phenotypes. Researchers interested in pursuing studies involving specific myocyte subtypes require a more directed differentiation approach. By treating mouse embryonic stem (ES) cells with Grem2, a secreted BMP antagonist that is necessary for atrial chamber formation in vivo, a large number of cardiac cells with an atrial phenotype can be generated. Use of the engineered Myh6-DSRed-Nuc pluripotent stem cell line allows for identification, selection, and purification of cardiomyocytes. In this protocol embryoid bodies are generated from Myh6-DSRed-Nuc cells using the hanging drop method and kept in suspension until differentiation day 4 (d4). At d4 cells are treated with Grem2 and plated onto gelatin coated plates. Between d8-d10 large contracting areas are observed in the cultures and continue to expand and mature through d14. Molecular, histological and electrophysiogical analyses indicate cells in Grem2-treated cells acquire atrial-like characteristics providing an in vitro model to study the biology of atrial cardiomyocytes and their response to various pharmacological agents.
Asunto(s)
Técnicas de Reprogramación Celular/métodos , Miocitos Cardíacos/citología , Células Madre Pluripotentes/citología , Animales , Diferenciación Celular , Citocinas , Atrios Cardíacos/citología , Ratones , Miocitos Cardíacos/efectos de los fármacos , Células Madre Pluripotentes/efectos de los fármacos , Proteínas/farmacologíaRESUMEN
The bone morphogenetic protein antagonist Gremlin 2 (Grem2) is required for atrial differentiation and establishment of cardiac rhythm during embryonic development. A human Grem2 variant has been associated with familial atrial fibrillation, suggesting that abnormal Grem2 activity causes arrhythmias. However, it is not known how Grem2 integrates into signaling pathways to direct atrial cardiomyocyte differentiation. Here, we demonstrate that Grem2 expression is induced concurrently with the emergence of cardiovascular progenitor cells during differentiation of mouse embryonic stem cells (ESCs). Grem2 exposure enhances the cardiogenic potential of ESCs by 20-120-fold, preferentially inducing genes expressed in atrial myocytes such as Myl7, Nppa, and Sarcolipin. We show that Grem2 acts upstream to upregulate proatrial transcription factors CoupTFII and Hey1 and downregulate atrial fate repressors Irx4 and Hey2. The molecular phenotype of Grem2-induced atrial cardiomyocytes was further supported by induction of ion channels encoded by Kcnj3, Kcnj5, and Cacna1d genes and establishment of atrial-like action potentials shown by electrophysiological recordings. We show that promotion of atrial-like cardiomyocytes is specific to the Gremlin subfamily of BMP antagonists. Grem2 proatrial differentiation activity is conveyed by noncanonical BMP signaling through phosphorylation of JNK and can be reversed by specific JNK inhibitors, but not by dorsomorphin, an inhibitor of canonical BMP signaling. Taken together, our data provide novel mechanistic insights into atrial cardiomyocyte differentiation from pluripotent stem cells and will assist the development of future approaches to study and treat arrhythmias.