Iodothyronine deiodinases: a functional and evolutionary perspective

    1. Carlota García-G1
    1. Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Boulevard Juriquilla 3001, Juriquilla, Querétaro 76230, México
      1Departamento de Investigación Biomédica, Facultad de Medicina, Universidad Autónoma de Querétaro, Clavel 200, Querétaro 76017, México
    1. (Correspondence should be addressed to A Orozco; Email: aureao{at}


    From an evolutionary perspective, deiodinases may be considered pivotal players in the emergence and functional diversification of both thyroidal systems (TS) and their iodinated messengers. To better understand the evolutionary pathway and the concomitant functional diversification of vertebrate deiodinases, in the present review we summarized the highlights of the available information regarding this ubiquitous enzymatic component that represents the final, common physiological link of TS. The information reviewed here suggests that deiodination of tyrosine metabolites is an ancient feature of all chordates studied to date and consequently, that it precedes the integration of the TS that characterize vertebrates. Phylogenetic analysis presented here points to D1 as the oldest vertebrate deiodinase and to D2 as the most recent deiodinase gene, a hypothesis that agrees with the notion that D2 is the most specialized and finely regulated member of the family and plays a key role in vertebrate neurogenesis. Thus, deiodinases seem to be major participants in the evolution and functional expansion of the complex regulatory network of TS found in vertebrates.

    • Received in final form 27 July 2012
    • Accepted 3 August 2012
    • Made available online as an Accepted Preprint 7 August 2012
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