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Genomic analysis distinguishes phases of early development of the mouse atrio-ventricular canal.

ABSTRACT: Valve formation during embryonic heart development involves a complex interplay of regional specification, cell transformations, and remodeling events. While many studies have addressed the role of specific genes during this process, a global understanding of the genetic basis for the regional specification and development of the heart valves is incomplete. We have undertaken genome-wide transcriptional profiling of the developing heart valves in the mouse. Four Serial Analysis of Gene Expression libraries were generated and analyzed from the mouse atrio-ventricular canal (AVC) at embryonic days 9.5-12.5, covering the stages from initiation of endothelial to mesenchymal transition (EMT) through to the beginning of endocardial cushion remodeling. We identified 14 distinct temporal patterns of gene expression during AVC development. These were associated with specific functions and signaling pathway members. We defined the temporal distribution of mesenchyme genes during the EMT process and of specific Notch and transforming growth factor-beta targets. This work provides the first comprehensive temporal dataset during the formation of heart valves. These results identify molecular signatures that distinguish different phases of early heart valve formation allowing gene expression and function to be further investigated.

SUBMITTER: Vrljicak P

PROVIDER: S-EPMC2825764 | biostudies-literature | 2010 Feb

REPOSITORIES: biostudies-literature

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Genomic analysis distinguishes phases of early development of the mouse atrio-ventricular canal.

Vrljicak Pavle P Chang Alex C Y AC Morozova Olena O Wederell Elizabeth D ED Niessen Kyle K Marra Marco A MA Karsan Aly A Hoodless Pamela A PA

Physiological genomics 20091201 3

Valve formation during embryonic heart development involves a complex interplay of regional specification, cell transformations, and remodeling events. While many studies have addressed the role of specific genes during this process, a global understanding of the genetic basis for the regional specification and development of the heart valves is incomplete. We have undertaken genome-wide transcriptional profiling of the developing heart valves in the mouse. Four Serial Analysis of Gene Expressio ...[more]

PMID: 19952280

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Project description:Malformations of the cardiovascular system are the most common type of birth defect in humans, affecting predominantly the formation of valves and septa. During heart valve and septa formation, cells from the atrio-ventricular canal (AVC) and outflow tract (OFT) regions of the heart undergo an epithelial-to-mesenchymal transformation (EMT) and invade the underlying extracellular matrix to give rise to endocardial cushions. Subsequent maturation of newly formed mesenchyme cells leads to thin stress-resistant leaflets. TWIST1 is a basic helix-loop-helix transcription factor expressed in newly formed mesenchyme cells of the AVC and OFT that has been shown to play roles in cell survival, cell proliferation and differentiation. However, the role and downstream targets of TWIST1 during heart valve formation remain unclear. To identify genes important for heart valve development downstream of Twist1 we performed global gene expression profiling of AVC, OFT, atria and ventricles of the embryonic day 10.5 mouse heart by tag-sequencing (Tag-seq). Using this resource we identified a novel set of 1246 genes, including 201 regulators of transcription, enriched in the valve forming regions of the heart. We compared these genes to a Tag-seq library from the Twist1 null developing valves revealing significant gene expression changes. These changes were consistent with a role of TWIST1 in controlling differentiation of mesenchymal cells following their transformation from endothelium in the mouse. To study the role of TWIST1 at the DNA level we performed chromatin immunoprecipitation and identified novel direct targets of TWIST1 in the developing heart valves. Our findings are consistent with a role for TWIST1 in the differentiation of AVC mesenchyme post-EMT in the mouse, and suggest that TWIST1 exerts its function by direct DNA binding to activate valve specific gene expression. Profiled the AVC, OFT, atria and ventricles of the embryonic day 10.5 mouse heart by tag-sequencing (Tag-seq) (no replicates). We also produced a Tag-seq library from Twist1 null developing valves to reveal the gene expression changes associated with loss of this gene.

Project description:PurposeWhile in the past, most clinical trial applications (CTAs) following non-integrated (standard) protocols were used to investigate one primary objective concerning a (new) drug, nowadays, the use of integrated protocols investigating multiple objectives within the same CTA becomes more and more popular. The aims of the present study were to investigate the usage and the impact of integrated protocols on regulatory activities and to find the motivation for their increasing use.MethodsTwo thousand nine hundred sixty-nine phase I and I/II CTAs submitted to the German Federal Institute for Drugs and Medical Devices (BfArM) during the time period from August 1, 2004, until August 31, 2014, were analysed with regard to protocol and sponsor status, duration until initial authorisation and the number of substantial amendments and their respective approval times. Additionally, applicants who submitted integrated protocols to BfArM were interviewed with respect to their opinion on integrated protocols in an online survey.ResultsThe percentage of integrated protocols has constantly increased by approximately 10% within the last 10 years from 17.9% in 2004 to 28.2% in 2014. It could be shown that authorisation procedures with single integrated protocols take significantly longer until initial authorisation (58 vs. 53 days) requires more substantial amendments (1.9 vs. 1.2 amendments per CTA) and the approval of the entirety of amendments takes longer to process as compared to standard protocols (22 vs. 14 days). Nevertheless, applicants prefer the use of integrated protocols due to higher time and cost economy for the entire phase I development process.ConclusionAlthough clinical trials (CTs) following integrated protocols are partly more time-consuming and costly, still, time and/or money may be saved during drug development due to the fact that overall, fewer CTs are needed than with standard protocols. Hence, the main reason for the increasing use of integrated protocols is improved time and cost efficiencies when conducting CTs.

Dataset Information

Genomic analysis distinguishes phases of early development of the mouse atrio-ventricular canal.

Publications

Genomic analysis distinguishes phases of early development of the mouse atrio-ventricular canal.

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