Development and evolution of the metazoan heart

Abstract

The mechanisms of the evolution and development of the heart in metazoans are highlighted, starting with the evolutionary origin of the contractile cell, supposedly the precursor of cardiomyocytes. The last eukaryotic common ancestor is likely a combination of several cellular organisms containing their specific metabolic pathways and genetic signaling networks. During evolution, these tool kits diversified. Shared parts of these conserved tool kits act in the development and functioning of pumping hearts and open or closed circulations in such diverse species as arthropods, mollusks, and chordates. The genetic tool kits became more complex by gene duplications, addition of epigenetic modifications, influence of environmental factors, incorporation of viral genomes, cardiac changes necessitated by air‐breathing, and many others. We evaluate mechanisms involved in mollusks in the formation of three separate hearts and in arthropods in the formation of a tubular heart. A tubular heart is also present in embryonic stages of chordates, providing the septated four‐chambered heart, in birds and mammals passing through stages with first and second heart fields. The four‐chambered heart permits the formation of high‐pressure systemic and low‐pressure pulmonary circulation in birds and mammals, allowing for high metabolic rates and maintenance of body temperature. Crocodiles also have a (nearly) separated circulation, but their resting temperature conforms with the environment. We argue that endothermic ancestors lost the capacity to elevate their body temperature during evolution, resulting in ectothermic modern crocodilians. Finally, a clinically relevant paragraph reviews the occurrence of congenital cardiac malformations in humans as derailments of signaling pathways during embryonic development.

Come Together: Protein Assemblies, Aggregates and the Sarcostat at the Heart of Cardiac Myocyte Homeostasis

“…Evolving over the previous 600 million years (Poelmann and Gittenberger-de Groot, 2019), the metazoan circulatory system is at the center of the explosion of multicellular functionality, culminating in the human era. From primordial heart tubes in early protostomes to the fourchambered hearts of mammals, each of these circulations have ensured nutrient and oxygen supply, maintenance of temperature, as well as waste removal.…”

Three distinct mechanisms, Notch instructive, permissive, and independent, regulate the expression of two different pericardial genes to specify cardiac cell subtypes

“…In both Drosophila and vertebrates, heart development entails the division, diversification, and differentiation of a pool of cardiac mesodermal cells into distinct cardiac subtypes [ 5 , 44 – 47 ]. In Drosophila , the two major heart subtypes are cardial and pericardial cells.…”

Reptiles as a Model System to Study Heart Development

“…Heart development in vertebrates rely on a core network of transcription factors that is evolutionarily conserved (Olson 2006;Kokubo et al 2010;Bakkers 2011;Kelly et al 2014;Diogo et al 2015;Poelmann and Gittenberger-de Groot 2019). Transcription factors such as Tbx20, Tbx5, and Nkx2.5 are required for the formation of chambers in mouse (Bruneau et al 1999;Kraus et al 2001;Stennard et al 2003) and are broadly expressed in the heart of reptiles ( Fig.…”