A preprogalanin cDNA from the turtle pituitary and regulation of its gene expression.
Galanin is a hormone 29 or 30 amino acids (aa) long that is widely distributed within the body and exerts numerous biological effects in vertebrates. To fully understand its physiological roles in reptiles, we analyzed preprogalanin cDNA structure and expression in the turtle pituitary. Using the Chinese soft-shell turtle (Pelodiscus sinensis order Testudines), we obtained a 672-base pair (bp) cDNA containing a 99-bp 5'-untranslated region, a 324-bp preprogalanin coding region, and a 249-bp 3'-untranslated region. The open-reading frame encoded a 108-aa preprogalanin protein with a putative 23-aa signal sequence at the NH(2) terminus. Based on the location of putative Lys-Arg dibasic cleavage sites and an amidation signal of Gly-Lys-Arg, we propose that turtle preprogalanin is processed to yield a 29-aa galanin peptide with Gly(1) and Thr(29) substitutions and a COOH-terminal amidation. Sequence comparison revealed that turtle preprogalanin and galanin-29 had 48-81% and 76-96% aa identities with those of other vertebrates, respectively, suggesting their conservative nature. Expression of the turtle galanin gene was detected in the pituitary, brain, hypothalamus, stomach, liver, pancreas, testes, ovaries, and intestines, but not in the adipose or muscle tissues, suggesting tissue-dependent differences. An in vitro study that used pituitary tissue culture indicated that treatment with 17beta-estradiol, testosterone, or gonadotropin-releasing hormone resulted in increased galanin mRNA expression with dose- or time-dependent differences, whereas leptin and neuropeptide Y reduced galanin mRNA levels. These results suggest a hormone-dependent effect on hypophyseal galanin mRNA expression.
Yu
John Yuh-Lin
JY
Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan.
Pon
Chin-Hon
CH
Ku
Hui-Chen
HC
Wang
Chih-Ting
CT
Kao
Yung-Hsi
YH
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D018388:Codon, Terminator; D018076:DNA, Complementary / Q000032:analysis; D019004:Galanin / Q000235:genetics*; D005786:Gene Expression Regulation; D005998:Glycine / Q000378:metabolism; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010902:Pituitary Gland / Q000737:chemistry*; D011498:Protein Precursors / Q000737:chemistry / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D013912:Threonine / Q000378:metabolism; D014426:Turtles / Q000235:genetics* / Q000502:physiology
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D018388:Codon, Terminator; D018076:DNA, Complementary; D011498:Protein Precursors; D012333:RNA, Messenger; D013912:Threonine; D019004:Galanin; D005998:Glycine