The full agonistic effect of recombinant 20 kDa human growth hormone (hGH) on CHO cells stably transfected with hGH receptor cDNA.
The agonistic effect of the recombinant 20 kilodalton human GH (20K-hGH) with authentic primary structure was studied using Chinese hamster ovary (CHO) cells stably transfected with hGH receptor (hGHR) cDNA and was compared with that of 22K-hGH. The binding affinities (dissociation constants) of 20K- and 22K-hGH were identical (0.41 +/- 0.11 nM and 0.41 +/- 0.04 nM, respectively). In addition, the two hGHs possessed the same potencies in activating the rat serine protease inhibitor (Spi) 2.1 gene promoter. 20K-hGH was similarly internalized as 22K-hGH but its internalization rate was a little slower than that of 22K-hGH. We also found that proliferation of CHO-hGHR cells stimulated by serum was remarkably inhibited by both hGHs to the same degree. In conclusion, both hGH isoforms exhibited the same binding affinities for hGHR and were potent enough to induce some hGHR-mediated cellular events. These suggest that 20K-hGH exerts a full agonistic activity for hGHR.
Wada
M
M
Life Science Laboratories, Central Research Institute, Mitsui Chemicals Inc., Mobara, Chiba, Japan. mitsufumi.wada@mitsui-chem.co.jp
Ikeda
M
M
Takahashi
Y
Y
Asada
N
N
Chang
K T
KT
Takahashi
M
M
Honjo
M
M
D000818:Animals; D001667:Binding, Competitive; D001769:Blood; D016466:CHO Cells; D002455:Cell Division; D006224:Cricetinae; D018076:DNA, Complementary / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D013006:Growth Hormone / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D008024:Ligands; D009687:Nuclear Proteins / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D051381:Rats; D011986:Receptors, Somatotropin / Q000819:agonists* / Q000235:genetics* / Q000378:metabolism; D015533:Transcriptional Activation / Q000502:physiology*; D014162:Transfection
D018076:DNA, Complementary; C091103:LOC299282 protein, rat; D008024:Ligands; D009687:Nuclear Proteins; D011986:Receptors, Somatotropin; D013006:Growth Hormone