tailieunhanh - Báo cáo khoa học: Evolutionary changes to transthyretin: evolution of transthyretin biosynthesis

Thyroid hormones are involved in growth and development, particularly of the brain. Thus, it is imperative that these hormones get from their site of synthesis to their sites of action throughout the body and the brain. This role is fulfilled by thyroid hormone distributor proteins. Of particular inter-est is transthyretin, which in mammals is synthesized in the liver, choroid plexus, meninges | MINIREVIEW Evolutionary changes to transthyretin evolution of transthyretin biosynthesis Samantha J. Richardson Schoolof MedicalSciences RMIT University Bundoora Vic. Australia Keywords amphibians birds brain choroid plexus eutherians evolution fish gene regulation liver marsupials monotremes reptiles thyroid hormones transthyretin vertebrates Correspondence S. J. Richardson Schoolof Medical Sciences RMIT University PO Box 71 Bundoora Vic. 3083 Australia Fax 61 3 9925 7063 Tel 61 3 9925 7897 E-mail Received 2 February 2009 revised 11 June 2009 accepted 12 June 2009 Thyroid hormones are involved in growth and development particularly of the brain. Thus it is imperative that these hormones get from their site of synthesis to their sites of action throughout the body and the brain. This role is fulfilled by thyroid hormone distributor proteins. Of particular interest is transthyretin which in mammals is synthesized in the liver choroid plexus meninges retinal and ciliary pigment epithelia visceral yolk sac placenta pancreas and intestines whereas the other thyroid hormone distributor proteins are synthesized only in the liver. Transthyretin is synthesized by all classes of vertebrates however the tissue specificity of transthyretin gene expression varies widely between classes. This review summarizes what is currently known about the evolution of transthyretin synthesis in vertebrates and presents hypotheses regarding tissue-specific synthesis of transthyretin in each vertebrate class. doi Introduction Thyroid hormones THs are essential for normal growth and development and for regulation of the basal metabolic rate. The two major thyroid hormones are 5 3 5 3-tetraiodo- L -thyronine thyroxine T4 and 3 5 3-triiodo- L -thyronine T3 . THs are synthesized by the thyroid gland and then secreted into the bloodstream see Fig. 1 . In mammals most of the TH produced by the thyroid gland is in the form of T4 which