All vertebrates have a definitive thyroid gland,or thyroid for short.As a critical organ for growth,development and metabolism,its origin and evolution have long received attention.On the basis of anatomical position,...All vertebrates have a definitive thyroid gland,or thyroid for short.As a critical organ for growth,development and metabolism,its origin and evolution have long received attention.On the basis of anatomical position,endodermal origination and histological features,the endostyle of amphioxus has been proposed as a homologue to the thyroid of vertebrates.This homology is further supported by the findings that the amphioxus endostyle abounds in thyroid hormones,possesses several thyroid-specific proteins such as thyroperoxidase,nicotinamide adenine dinucleotide phosphate(NADPH)oxidase and thyroglobulin,and expresses the thyroid-related transcription factors involved in the regulation of development of the vertebrate thyroid,including Nkx2.1,FoxE4 and Pax2/5/8.Importantly,our study on functionality,together with others,indicates significant similarities between the amphioxus endostyle and the vertebrate thyroid gland.Moreover,we show that the production of thyroid hormones by the amphioxus endostyle is mediated in a fashion similar to that of the vertebrate thyroid.These provide solid evidences that the amphioxus endostyle is the homologue of the vertebrate thyroid.From a phylogenetic viewpoint,we propose that the hypobranchial ridge,or endostyle-like structure,of hemichordates is the most primitive forerunner of the thyroid,from which the vertebrate thyroid is formed through the transformation of non-follicular endostyle of amphioxus to follicular endocrine organ of vertebrates.We also raise a couple of questions that demand further study.展开更多
基金The National Natural Science Foundation of China under contact No.32270434.
文摘All vertebrates have a definitive thyroid gland,or thyroid for short.As a critical organ for growth,development and metabolism,its origin and evolution have long received attention.On the basis of anatomical position,endodermal origination and histological features,the endostyle of amphioxus has been proposed as a homologue to the thyroid of vertebrates.This homology is further supported by the findings that the amphioxus endostyle abounds in thyroid hormones,possesses several thyroid-specific proteins such as thyroperoxidase,nicotinamide adenine dinucleotide phosphate(NADPH)oxidase and thyroglobulin,and expresses the thyroid-related transcription factors involved in the regulation of development of the vertebrate thyroid,including Nkx2.1,FoxE4 and Pax2/5/8.Importantly,our study on functionality,together with others,indicates significant similarities between the amphioxus endostyle and the vertebrate thyroid gland.Moreover,we show that the production of thyroid hormones by the amphioxus endostyle is mediated in a fashion similar to that of the vertebrate thyroid.These provide solid evidences that the amphioxus endostyle is the homologue of the vertebrate thyroid.From a phylogenetic viewpoint,we propose that the hypobranchial ridge,or endostyle-like structure,of hemichordates is the most primitive forerunner of the thyroid,from which the vertebrate thyroid is formed through the transformation of non-follicular endostyle of amphioxus to follicular endocrine organ of vertebrates.We also raise a couple of questions that demand further study.
