Ghrelin and truncated ghrelin variant plasmid vectors administration into skeletal muscle augments long-term growth in rats.
Ghrelin is an acylated peptide recently identified as an endogenous ligand for the growth hormone (GH) secretagogues (GHSs) receptor (GHS-R) and is involved in a novel system for regulating GH release. To study the biological activities of ghrelin using plasmid vector administration, we constructed myogenic expression vectors containing the full length cDNA of swine ghrelin-28 (pGEM-wt-sGhln) and truncated variant (pGEM-tmt-sGhln) consisting of the first seven residues of ghrelin (including Ser3 substituted with Trp3) with addition of a basic amino acid, Lys (K) at the C-terminus. After intramuscular injection of pGEM-wt-sGhln and pGEM-tmt-sGhln, RT-PCR analysis demonstrated that the ectopic expressions of ghrelin and its variant were observed 30 days post-injection. The level of GH increased in rat serum, and was significantly higher than that of the control group 20 days post-injection with pGEM-tmt-sGhln (P < 0.05). Administration of 150 microg of pGEM-wt-sGhln and pGEM-tmt-sGhln enhanced growth in rats over 30 days and great stimulatory responses were observed at day 10 and 20 post-injection respectively, whose body weight gains were on average 15% (P < 0.05) and 21% P < 0.033 significantly heavier than controls. These results suggested that skeletal muscle might have the potential to perform post-translational acylation for ghrelin, and short ghrelin variant might have the biological effects as wild type ghrelin.
Xie
Q F
QF
State Key Laboratory for Agrobiotechnology, China Agricultural University, Beijing 100094 [corrected]
Wu
C X
CX
Meng
Q Y
QY
Li
N
N
D000215:Acylation; D000595:Amino Acid Sequence; D000818:Animals; D015870:Gene Expression; D005822:Genetic Vectors; D054439:Ghrelin; D013006:Growth Hormone / Q000097:blood; D007273:Injections, Intramuscular; D008297:Male; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000378:metabolism*; D010446:Peptide Fragments; D036361:Peptide Hormones / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D010957:Plasmids / Q000235:genetics*; D011499:Protein Processing, Post-Translational; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013552:Swine / Q000235:genetics; D015430:Weight Gain
D054439:Ghrelin; D010446:Peptide Fragments; D036361:Peptide Hormones; D013006:Growth Hormone