Publisher Correction: The role of cardiac transcription factor NKX2-5 in regulating the human cardiac miRNAome.

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The role of cardiac transcription factor NKX2-5 in regulating the human cardiac miRNAome.

MicroRNAs (miRNAs) are translational regulatory molecules with recognised roles in heart development and disease. Therefore, it is important to define the human miRNA expression profile in cardiac progenitors and early-differentiated cardiomyocytes and to determine whether critical cardiac transcription factors such as NKX2-5 regulate miRNA expression. We used an NKX2-5eGFP/w reporter line to isolate both cardiac committed mesoderm and cardiomyocytes. We identified 11 miRNAs that were differentially expressed in NKX2-5 -expressing cardiac mesoderm compared to non-cardiac mesoderm. Subsequent profiling revealed that the canonical myogenic miRNAs including MIR1-1, MIR133A1 and MIR208A were enriched in cardiomyocytes. Strikingly, deletion of NKX2-5 did not result in gross changes in the cardiac miRNA profile, either at committed mesoderm or cardiomyocyte stages. Thus, in early human cardiomyocyte commitment and differentiation, the cardiac myogenic miRNA program is predominantly regulated independently of the highly conserved NKX2-5 -dependant gene regulatory network.

Derivation of endothelial cells from human embryonic stem cells in fully defined medium enables identification of lysophosphatidic acid and platelet activating factor as regulators of eNOS localization.

The limited availability of human vascular endothelial cells (ECs) hampers research into EC function whilst the lack of precisely defined culture conditions for this cell type presents problems for addressing basic questions surrounding EC physiology. We aimed to generate endothelial progenitors from human pluripotent stem cells to facilitate the study of human EC physiology, using a defined serum-free protocol. Human embryonic stem cells (hESC-ECs) differentiated under serum-free conditions generated CD34(+)KDR(+) endothelial progenitor cells after 6days that could be further expanded in the presence of vascular endothelial growth factor (VEGF). The resultant EC population expressed CD31 and TIE2/TEK, took up acetylated low-density lipoprotein (LDL) and up-regulated expression of ICAM-1, PAI-1 and ET-1 following treatment with TNFα. Immunofluorescence studies indicated that a key mediator of vascular tone, endothelial nitric oxide synthase (eNOS), was localised to a perinuclear compartment of hESC-ECs, in contrast with the pan-cellular distribution of this enzyme within human umbilical vein ECs (HUVECs). Further investigation revealed that that the serum-associated lipids, lysophosphatidic acid (LPA) and platelet activating factor (PAF), were the key molecules that affected eNOS localisation in hESC-ECs cultures. These studies illustrate the feasibility of EC generation from hESCs and the utility of these cells for investigating environmental cues that impact on EC phenotype. We have demonstrated a hitherto unrecognized role for LPA and PAF in the regulation of eNOS subcellular localization.

Relative contribution of the prenatal versus postnatal period on development of hypertension and growth rate of the spontaneously hypertensive rat.

1. To determine the relative roles of the prenatal and postnatal (preweaning) environment on the development of blood pressure and growth rate in the spontaneously hypertensive rat (SHR) of the Okamoto strain, we used combined embryo transfer and cross-fostering techniques between SHR and normotensive Wistar-Kyoto (WKY) rats to produce offspring whose development was examined during the first 20 weeks of life. 2. We measured litter sizes, bodyweights and tail-cuff blood pressures in offspring at 4, 8, 12 and 20 weeks of age. We also recorded heart, kidney and adrenal weights at 20 weeks of age, when the study concluded. 3. We found that both the in utero and postnatal environments provided by the SHR mother could significantly affect WKY rat offspring growth rates, but blood pressure was unaffected in this strain. In SHR offspring, the SHR maternal in utero and suckling period both contributed to the rate of blood pressure development in the SHR, but not the final blood pressure of offspring at 20 weeks of age. This effect was greater for male than female offspring. Organ weights were largely unaffected by the perinatal environment in either strain. 4. We conclude that although the SHR maternal in utero and immediate postnatal environment both contribute to the rate of blood pressure development in the SHR, they do not appear to contribute to the final blood pressure of offspring at maturity. The SHR maternal environment also alters growth rate that may, in turn, underlie these effects on SHR blood pressure development, particularly in males.

Lack of evidence for a role for either the in utero or suckling periods in the exaggerated salt preference of the spontaneously hypertensive rat.

When offered as a choice with drinking water in two-bottle preference tests, the spontaneously hypertensive rats (SHR) of the Okamoto strain exhibit a marked preference for saline solutions. While this behaviour is thought to be in part genetically determined, the role of environmental influences-in particular, perinatal ones-are poorly understood. In this study, we have used combined embryo transfer and cross-fostering techniques between SHR and normotensive Wistar Kyoto (WKY) rats to delineate the relative roles of the prenatal and postnatal, suckling environment on the exaggerated saline preference of male SHR and WKY offspring at 20 weeks of age. We found, using two-bottle preference tests using water and 140 mmol/l sodium chloride solution, that neither the in utero period nor the postnatal, suckling period played a role in the development of the much larger total fluid intake (water plus saline) or saline preference (proportion of the total fluid intake taken as saline) of the SHR. We thus conclude that maternal and perinatal environmental factors do not play a major role in this behaviour and that the exaggerated saline preference of the SHR is probably largely genetically determined.