Evolution

An Early Use of Androstenedione

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Science  10 Aug 2007:
Vol. 317, Issue 5839, pp. 723
DOI: 10.1126/science.317.5839.723d

Sex hormones such as estrogen, progesterone, and androgen exert their physiological effects by binding to proteins of the steroid hormone receptor family. Studies with basal vertebrates have mapped out the evolution of these signaling pathways, which are important in regulating reproduction. Prior work has suggested that the estrogen receptor was the first steroid receptor and that other steroid receptors arose later, probably through gene duplication. Although androgens are generally traced back to gnathostomes, Bryan et al. now identify an androgen receptor in the sea lamprey Petromyzon marinus, a jawless vertebrate. The specific androgen, androstenedione, is a precursor of testosterone, and when androstenedione was implanted into male lampreys, the development of the testis and secondary male characteristics was accelerated. Hence, by showing that a functional androgenic hormone and its receptor are present in jawless vertebrates, this work argues against the claim that androgen receptors evolved after agnathan-gnathostome divergence. — BAP

Biol. Reprod. 77, 10.1095/biolreprod.107.061093 (2007).

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