PMC:5003481 / 1869-4539
Annnotations
{"target":"https://pubannotation.org/docs/sourcedb/PMC/sourceid/5003481","sourcedb":"PMC","sourceid":"5003481","source_url":"https://www.ncbi.nlm.nih.gov/pmc/5003481","text":"1. Introduction\nCardiac development is a complex process in which multiple cell types are integrated. Two distinct populations of cells contribute to the developing heart, a first heart field (FHF), which mainly leads to the left ventricle, and a second heart field (SHF), which contributes to the rest of the heart [1]. Commitment from the mesodermal lineage into the cardiomyocyte lineage seems to be equally achieved for the FHF and SHF precursors. Both FHF and SHF precursors are mainly dependent on Bmp and Fgf signaling, resulting on the activation of the core cardiac transcriptional machinery, i.e., Mef2, Gata, Nkx2.5 and Srf [2]. However, FHF cells are characterized by constitutive expression of Nkx2.5 with only a transient islet-1 expression, whereas SHF cells display strong and constitutive expression of Nkx2.5 and islet-1, providing the first insights into cardiac transcriptional heterogeneity [2]. As development of heart proceeds, distinct cardiomyocyte cell types are established, with distinct cellular, molecular and functional characteristics [3]. Transcriptional regulators, such as T-box, Hands and Pitx2 genes, participate on these processes [4]. In addition to cardiomyocyte formation, the heart develops two additional tissue layers, an inner endothelial lining (endocardium) and external epicardial layer (epicardium). Contribution to the formed heart from these two layers is complex; at discrete regions, the endocardium leads to an epithelial-to-mesenchymal transformation (EMT) configuring the endocardial cushions [5,6], whereas the epicardium displays also a similar EMT transformation, intermingling across the cardiomyocytes and contributing to the formation of the interstitial cells and the coronary vasculature [7,8]. Understanding of the transcriptional control of EMT in both the endocardium and epicardium is emerging, with key roles for Ets, Wt-1 and Snail/Slug transcription factors. In addition to the role of transcriptional regulation, a new layer of complexity is emerging, as non-coding RNAs are also capable of playing a pivotal role during cardiogenesis [9]. microRNAs are non-coding RNA with an average length of 22–24 nucleotides, which are capable of interacting with the 3' untranslated region of coding RNAs (mRNAs), leading to blockage of protein translation and/or mRNA degradation [10]. Understanding microRNA biogenesis has been achieved at a quick pace; however, knowledge about the tissue distribution and functional consequences remains more elusive. However, there is an increasing body of evidence that suggests a highly relevant role of microRNAs in multiple aspects of cardiac development and disease.","divisions":[{"label":"Title","span":{"begin":0,"end":15}}],"tracks":[{"project":"2_test","denotations":[{"id":"27605182-22449840-69477420","span":{"begin":317,"end":318},"obj":"22449840"},{"id":"27605182-17350578-69477421","span":{"begin":636,"end":637},"obj":"17350578"},{"id":"27605182-17350578-69477422","span":{"begin":913,"end":914},"obj":"17350578"},{"id":"27605182-12871041-69477423","span":{"begin":1068,"end":1069},"obj":"12871041"},{"id":"27605182-16787195-69477424","span":{"begin":1170,"end":1171},"obj":"16787195"},{"id":"27605182-22656450-69477425","span":{"begin":1550,"end":1551},"obj":"22656450"},{"id":"27605182-22579502-69477426","span":{"begin":1552,"end":1553},"obj":"22579502"},{"id":"27605182-11399849-69477427","span":{"begin":1753,"end":1754},"obj":"11399849"},{"id":"27605182-14699633-69477428","span":{"begin":1755,"end":1756},"obj":"14699633"},{"id":"27605182-20412767-69477429","span":{"begin":2108,"end":2109},"obj":"20412767"},{"id":"27605182-21778437-69477430","span":{"begin":2343,"end":2345},"obj":"21778437"}],"attributes":[{"subj":"27605182-22449840-69477420","pred":"source","obj":"2_test"},{"subj":"27605182-17350578-69477421","pred":"source","obj":"2_test"},{"subj":"27605182-17350578-69477422","pred":"source","obj":"2_test"},{"subj":"27605182-12871041-69477423","pred":"source","obj":"2_test"},{"subj":"27605182-16787195-69477424","pred":"source","obj":"2_test"},{"subj":"27605182-22656450-69477425","pred":"source","obj":"2_test"},{"subj":"27605182-22579502-69477426","pred":"source","obj":"2_test"},{"subj":"27605182-11399849-69477427","pred":"source","obj":"2_test"},{"subj":"27605182-14699633-69477428","pred":"source","obj":"2_test"},{"subj":"27605182-20412767-69477429","pred":"source","obj":"2_test"},{"subj":"27605182-21778437-69477430","pred":"source","obj":"2_test"}]}],"config":{"attribute types":[{"pred":"source","value type":"selection","values":[{"id":"2_test","color":"#d793ec","default":true}]}]}}