PHYLOGENETIC ANALYSIS OF THE HUMAN THYROID-STIMULATING HORMONE

Abstract

Background: Thyroid-stimulating hormone (TSH) is a member of the vertebrate glycoprotein hormone family [1]. It’s secreted from pituitary cells as heterodimers composed of an alpha and a beta- subunit. The thyrotrophic cells that secrete TSH are preferentially located in the anteromedial and anterolateral portions of the pituitary. Objective: We performed a phylogenetic analysis of the TSH, and phylogram of the maximum likelihood relations between TSH coding sequences of five representative species. Methods: We extracted the available DNA and protein sequences for TSH from the NCBI databank. Searched for regions presenting sequence similarities to the constituent domains of TSH – alpha and beta-subunits - with the Blastall command ftp://ftp.ncbi.nlm.nih.gov/blast/db/ website, pairs of sequences were compared on the basis of their global alignment with the Myers & Millers algorithm manpages.ubuntu. com/manpages/karmic/man1, and the phylogenetic reconstructions were performed online by using a maximum likelihood method with PhyMyL 3.0 software on the website file (http://www.phylogeny.fr/). Results: The comparison of the phylogenetic trees that we obtained compared with those studies previously published revealed similar subclusters with high protein homology. Conclusion: This study demonstrates that human TSH is structurally related to TSH of the species analysed, Bos taurus, Mus musculus, Canis lupus familiaris, and Cyprinus carpio, respectively.