Reverse transcription PCR showed that mRNA encoding the neurohormones growth hormone-releasing factor (GRF) and GH, and its receptor GH-R, together with IGF-1 splice variants and IGFBPs are expressed by inflammatory c...
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Reverse transcription PCR showed that mRNA encoding the neurohormones growth hormone-releasing factor (GRF) and GH, and its receptor GH-R, together with IGF-1 splice variants and IGFBPs are expressed by inflammatory cells found in the normal human airway. Unfractionated BALC moderately express GRF, GH and GH-R, IGFBP-2 to IGFBP-6, and IGFBP-rPI. In addition, BALC preferentially express the class 1 IGF-1Ea splice variant of the IGF-1 gene. A similar pattern of expression occurs in purified AM, except they do not appear to express GH-R. In marked contrast, AM precursor peripheral blood monocytes, do not express neuropeptides or IGF-1 and only express IGFBP-1, -4 and -6 and IGFBP-rPI. These data suggest that normal human inflammatory airway cells possess a powerful array of neurohormones and IGFBPs that are available for modulating local IGF-1 bioavailability in the lung. (C) 2000 Harcourt Publishers Ltd.
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, transgen...
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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.
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