Meeting Abstract
18.6 Sunday, Jan. 4 IDENTIFICATION OF A GLYCOPROTEIN HORMONE ALPHA SUBUNIT IN THE SEA LAMPREY, PETROMYZON MARINUS WILMOT, Michael*; KOSUGI, Takayoshi; FREAMAT, Mihael; SCHULTZ, Bernadine; SOWER, Stacia A.; University of New Hampshire, Durham; University of New Hampshire Durham; University of New Hampshire, Durham; University of New Hampshire, Durham; University of New Hampshire, Durham sasower@cisunix.unh.edu
The pituitary glycoprotein hormone family in gnathostomes consists of the gonadotropins (GTHs), luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and one thyroid-stimulating hormone (TSH). The alpha subunit of FSH, LH, and TSH is common within a single species, while the beta subunit is unique to each and confers specificity. Another heterodimeric glycoprotein hormone was recently discovered and termed thyrostimulin for its ability to stimulate TSH receptors in the thyroid (Nakabayashi et al, 2002). However, the thyrostimulin alpha subunit (GPA2) is not identical to the alpha subunit (GPA1) of FSH, LH and TSH. In the lamprey, an agnathan (jawless vertebrate), a gonadotropin beta subunit cDNA was cloned (Sower et. al, 2006). It is proposed from these studies that lampreys, a basal vertebrate, have only one pituitary gonadotropin. The objective of this study was to identify and clone the cDNA of the GTH alpha subunit. Thus far, a 292-nucleotide portion of a cDNA encoding a putative glycoprotein hormone alpha 2 (GPA2) subunit has been cloned by PCR from lamprey pituitary cDNA. Gene-specific primers were used to amplify a portion of the sequence identified from the lamprey genome (Pre!Ensembl, www.pre.ensembl.org), following TBLASTN searches with known GPA1 and GPA2 subunits. Comparison of this partial, translated sequence with known alpha sequences shows a higher similarity with GPA2 rather than GPA1 subunits. These data suggest that GPA2 may be the ancestral alpha subunit of the glycoprotein hormone family. Supported by a UNH UROP grant to MW and a NSF # 0421923 and USDA Hatch #332 to SAS.
