title: Induction of hypoxia-inducible factor-1alpha and activation of caspase-3 in hypoxia-reoxygenated bone marrow stroma is negatively regulated by the delayed production of substance P.
abstract: The bone marrow (BM), which is the major site of immune cell development in the adult, responds to different stimuli such as inflammation and hemorrhagic shock. Substance P (SP) is the major peptide encoded by the immune/hemopoietic modulator gene, preprotachykinin-1 (PPT-I). Differential gene expression using a microarray showed that SP reduced hypoxia-inducible factor-1alpha (HIF-1alpha) mRNA levels in BM stroma. Because long-term hypoxia induced the expression of PPT-I in BM mononuclear cells, we used timeline studies to determine whether PPT-I is central to the biologic responses of BM stroma subjected to 30-min hypoxia (pO(2) = 35 mm Hg) followed by reoxygenation. HIF-1alpha mRNA and protein levels were increased up to 12 h. At this time, beta-PPT-I mRNA was detected with the release of SP at 16 h. SP release correlated with down-regulation of HIF-1alpha to baseline. A direct role for SP in HIF-1alpha expression was demonstrated as follows: 1) transient knockout of beta-PPT-I showed an increase in HIF-1alpha expression up to 48 h of reoxygenation; and 2) HIF-1alpha expression remained baseline during reoxygenation when stroma was subjected to hypoxia in the presence of SP. Reoxygenation activated the PPT-I promoter with concomitant nuclear translocation of HIF-1alpha that can bind to the respective consensus sequences within the PPT-I promoter. SP reversed active caspase-3, an indicator of apoptosis and erythropoiesis, to homeostasis level after reoxygenation of hypoxic stroma. The results show that during reoxgenation the PPT-I gene acts as a negative regulator on the expression of HIF-1alpha and active caspase-3 in BM stroma subjected to reoxygenation.
authors.affiliation: Department of Medicine, Trauma Division, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA.
authors.forename: J
authors.initials: J
authors.lastname: Qian
authors.forename: K
authors.initials: K
authors.lastname: Ramroop
authors.forename: A
authors.initials: A
authors.lastname: McLeod
authors.forename: P
authors.initials: P
authors.lastname: Bandari
authors.forename: D H
authors.initials: DH
authors.lastname: Livingston
authors.forename: J S
authors.initials: JS
authors.lastname: Harrison
authors.forename: P
authors.initials: P
authors.lastname: Rameshwar
mesh_terms: D020121:5' Untranslated Regions; D000328:Adult; D001853:Bone Marrow / Q000378:metabolism*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D015687:Cell Hypoxia; D004789:Enzyme Activation; D005786:Gene Expression Regulation; D006410:Hematopoiesis; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D010100:Oxygen / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D011498:Protein Precursors / Q000235:genetics; D017154:Stromal Cells / Q000378:metabolism; D013373:Substance P / Q000096:biosynthesis*; D015320:Tachykinins / Q000235:genetics; D014157:Transcription Factors / Q000096:biosynthesis*
chemical_list: D020121:5' Untranslated Regions; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D011498:Protein Precursors; D015320:Tachykinins; D014157:Transcription Factors; C044206:preprotachykinin; D013373:Substance P; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D010100:Oxygen