title: Endothelin-induced differentiation of Nkx2.5⁺ cardiac progenitor cells into pacemaking cells.
abstract: The mechanisms governing the development of cardiac pacemaking and conduction system are not well understood. In order to provide evidence for the derivation of pacemaking cells and the signal that induce and maintain the cells in the developing heart, Nkx2.5(+) cardiac progenitor cells (CPCs) were isolated from embryonic heart tubes of rats. Endothelin-1 was subsequently added to the CPCs to induce differentiation of them towards cardiac pacemaking cells. After the treatment, Nkx2.5(+) CPCs displayed spontaneous beating and spontaneously electrical activity as what we have previously described. Furthermore, RT-PCR and immunofluorescence staining demonstrated that Tbx3 expression was increased and Nkx2.5 expression was decreased in the induced cells 4 days after ET-1 treatment. And the significantly increased expression of Hcn4 and connexin-45 were detected in the induced cells 10 days after the treatment. In addition, Nkx2.5(+) CPCs were transfected with pGCsi-Tbx3 4 days after ET-1 treatment in an attempt to determine the transcription regulatory factor governing the differentiation of the cells into cardiac pacemaking cells. The results showed that silencing of Tbx3 decreased the pacemaking activity and led to down-regulation of pacemaker genes in the induced cells. These results confirmed that Nkx2.5(+) CPCs differentiated into cardiac pacemaking cells after being treated with ET-1 and suggested that an ET-1-Tbx3 molecular pathway govern/mediate this process. In conclusion, our study support the notion that pacemaking cells originate from Nkx2.5(+) CPCs present in embryonic heart tubes and endothelin-1 might be involved in diversification of cardiomyogenic progenitors toward the cells.
authors.affiliation: Institute of Biomedical Engineering, The Second Military Medical University, Shanghai, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Zhang
authors.forename: Jin-Ping
authors.initials: JP
authors.lastname: Guo
authors.forename: Ya-Li
authors.initials: YL
authors.lastname: Chi
authors.forename: Yan-Chun
authors.initials: YC
authors.lastname: Liu
authors.forename: Chuan-Sen
authors.initials: CS
authors.lastname: Zhang
authors.forename: Xiang-Qun
authors.initials: XQ
authors.lastname: Yang
authors.forename: Hai-Yan
authors.initials: HY
authors.lastname: Lin
authors.forename: Er-Peng
authors.initials: EP
authors.lastname: Jiang
authors.forename: Shao-Hu
authors.initials: SH
authors.lastname: Xiong
authors.forename: Zhi-Ying
authors.initials: ZY
authors.lastname: Zhang
authors.forename: Bao-Hai
authors.initials: BH
authors.lastname: Liu
mesh_terms: D000200:Action Potentials; D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D017630:Connexins / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D019332:Endothelin-1 / Q000502:physiology*; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; D009200:Myocardial Contraction; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism; D061251:Primary Cell Culture; D051381:Rats; D017207:Rats, Sprague-Dawley; D012849:Sinoatrial Node / Q000166:cytology*; D013234:Stem Cells / Q000378:metabolism / Q000502:physiology*; D020825:T-Box Domain Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D017630:Connexins; D019332:Endothelin-1; C513836:HCN4 protein, rat; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins; D064428:Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels; C484469:Nkx2-5 protein, mouse; D015221:Potassium Channels; D020825:T-Box Domain Proteins; D014157:Transcription Factors; C082920:connexin 45