Development of a transgenic mouse that overexpresses a novel product of the growth hormone-releasing hormone gene.
The GH-releasing hormone (GHRH) precursor molecule contains a 30-amino acid C-terminal region that has been designated GHRH-related peptide (GHRH-RP). To begin to understand the physiological role of GHRH-RP, transgenic (Tg) mice that constituitively express this peptide were developed. To generate these mice, a transgene (SS-RP) was constructed by overlap primer extension PCR. This transgene, under the control of the mouse phosphoglycerate kinase gene, selectively expresses GHRH-RP, but not GHRH. Western blot analysis confirmed that the transgene produces GHRH-RP. Animals were evaluated for the effect of excess GHRH-RP on growth, fertility, behavior, stem cell factor (SCF) expression, and hematopoiesis. Northern blot and RT-PCR were used to demonstrate ubiquitous expression of the transgene in tissues from GHRH-RP Tg animals. These tissues also had marked overexpression of SCF messenger RNA compared with controls. Tg animals had significantly increased cell cycling for granulocyte-macrophage, erythroid, and multilineage progenitor cells. Transgenic animals did not differ from control mice in their growth, fertility, or behavior. These findings demonstrate, for the first time, that in vivo the C-terminal peptide of the pro-GHRH molecule is a biologically active peptide that is capable of stimulating the expression of SCF and hematopoiesis in vivo and suggests that GHRH-RP may play a role in normal blood cell development.
Fang
S
S
Department of Pediatrics, Indiana University School of Medicine, Indianapolis 46202, USA.
Steinmetz
R
R
Walker King
D
D
Zeng
P
P
Vogelweid
C
C
Cooper
S
S
Hangcoc
G
G
Broxmeyer
H E
HE
Pescovitz
O H
OH
D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D005298:Fertility / Q000502:physiology; D015870:Gene Expression; D013007:Growth Hormone-Releasing Hormone / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D006410:Hematopoiesis / Q000502:physiology; D051379:Mice; D008809:Mice, Inbred C3H; D008822:Mice, Transgenic / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019089:Stem Cell Factor / Q000235:genetics / Q000378:metabolism
D012333:RNA, Messenger; D019089:Stem Cell Factor; C099166:growth hormone releasing hormone-related peptide; D013007:Growth Hormone-Releasing Hormone