Thyroid Hormone Signalling in Human Evolution and Disease: A Novel Hypothesis.

Polyxeni Mantzouratou,Angelo Michele Lavecchia,Christodoulos Xinaris

doi:10.3390/jcm11010043

Abstract

Thyroid hormone (TH) signalling is a universally conserved pathway with pleiotropic actions that is able to control the development, metabolism, and homeostasis of organisms. Using evidence from paleoecology/palaeoanthropology and data from the physiology of modern humans, we try to assess the natural history of TH signalling and its role in human evolution. Our net thesis is that TH signalling has likely played a critical role in human evolution by facilitating the adaptive responses of early hominids to unprecedently challenging and continuously changing environments. These ancient roles have been conserved in modern humans, in whom TH signalling still responds to and regulates adaptations to present-day environmental and pathophysiological stresses, thus making it a promising therapeutic target.

Highlights

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The lives of the first unicellular organisms 3.5 billion years ago were crucially dependent on the availability of iodine, as it appears to have acted as a powerful antioxidant [3]
Starting with these ancestral antioxidant and catalyst roles, iodine coupled with tyrosine to form a more versatile and highly reactive molecule, iodotyrosine, which eventually formed iodothyronines through subsequent coupling reactions

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Due to these crucial roles in organisms’ adaptation to environmental conditions is not surprising that, over time, natural selection favoured the evolution of a sophisticated TH signalling that could sense and transmit environmental stimuli to cellular/genetic machinery (energy production, gene regulation and DNA replication in mitochondria), and orchestrate simultaneously metabolic and developmental processes.

Results

Conclusion