secondary heart field specification

Definition

Target type: biologicalprocess

The process that results in the delineation of a specific region of the lateral mesoderm into the area which will form the majority of the mesodermal component of the right ventricle, arterial pole (outflow tract) and venous pole (inflow tract). [GOC:mtg_heart, GOC:rl, PMID:17276708]

The secondary heart field (SHF) is a critical component of the developing heart, contributing to the formation of the right ventricle, outflow tract, and portions of the atria. Its specification is a complex process orchestrated by a precise interplay of signaling pathways, transcription factors, and cell fate decisions. Here's a detailed description:

**1. Initial Induction and Specification:**
* The SHF emerges from the anterior lateral mesoderm (ALM) in response to signals from the underlying endoderm and the overlying ectoderm.
* **Bone Morphogenetic Proteins (BMPs)**, secreted by the endoderm, induce SHF identity within the ALM.
* **Fibroblast Growth Factors (FGFs)**, primarily FGF8, are crucial for maintaining SHF fate and promoting proliferation.
* **Wnt Signaling:** Wnt pathway activity plays a role in defining the boundary between the SHF and the first heart field (FHF) and regulating cell fate decisions within the SHF.

**2. Migration and Integration:**
* Once specified, the SHF cells undergo a dynamic migration process, moving towards the developing heart tube, where they integrate with the FHF cells.
* **FGF10** and **Islet1 (ISL1)**, a transcription factor, are important for directing SHF cell migration.

**3. Differentiation and Morphogenesis:**
* Within the heart tube, SHF cells differentiate into various cell types, contributing to the distinct structures of the heart.
* **Nkx2.5** and **GATA4**, two key transcription factors, regulate SHF cell differentiation into cardiomyocytes (heart muscle cells), smooth muscle cells, and endothelial cells.
* **SHF cells contribute to the formation of the right ventricle, the outflow tract (aortic and pulmonary valves), and portions of the atria.**
* **SHF-derived cells also contribute to the development of the cardiac conduction system, which regulates heart rate and rhythm.**

**4. Regionalization:**
* The SHF is further subdivided into distinct regions with different developmental fates.
* **The anterior SHF contributes primarily to the outflow tract and right ventricle.**
* **The posterior SHF contributes to the atria.**
* **This regionalization is controlled by factors like **FGF8**, **Wnt signaling**, and **transcription factors** such as **Islet1** and **Hand1**.

**5. Interplay with First Heart Field:**
* The SHF and the FHF, the primary heart-forming region, interact extensively throughout development.
* **FGF signaling from the SHF influences FHF development.**
* **Cell-cell communication between the SHF and FHF is crucial for proper heart chamber formation and septation (division of the heart chambers).**

**Overall, the specification of the secondary heart field is a tightly regulated process involving a complex interplay of signaling pathways, transcription factors, and cell fate decisions. This precise coordination ensures the proper formation of the heart, a vital organ responsible for circulating blood throughout the body.**'
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Proteins (2)

Compounds (4)