Molecular Regulation of Pulmonary Vascular Tone
Over the past several years, our lab has been engaged in experiments that address the regulation of pulmonary vascular tone. We have investigated the signal transduction pathway of molecules that play an important role in determining pulmonary vascular tone. Relatively recently, we identified a novel, and controversial, role for HIF-1a in the regulation of tone in lung via effects on myosin light chain phosphorylation in the pulmonary artery smooth muscle cells and in regulating expression of the b1 subunit of the calcium sensitive potassium channel. Further, we outlined a novel role for endothelin derived from PASMC in modulating the pulmonary vascular response to hypoxia. Most recently, we have undertaken a line of research using human tissue to ensure fidelity between findings in mouse models and human biology.
Projects
Behavioral Studies of KCNMB1 Mice
Researchers: Elizabeth A. Barnes, David N. Cornfield
KCNMB1 is the gene for B1, a component of the calcium-sensitive potassium channel, BKCa. KCNMB1 is a target of HIF-1a transcriptional activity. We have previously shown that mice lacking KCNMB1 have an increase in PH when exposed to hypoxia. It has also been demonstrated that KCNMB1-null mice have modulated ethanol sensitivity, which influences alcohol dependence. Therefore, we propose to study the behavior of KCNMB1-null mice to determine how KCNMB1 adversely affects their mental physiology.
Characterization of the SM22a-PHD1/2 Mouse to Further Elucidate the Role of SM22a-HIF-1a in a Mouse Model of Hypoxia-induced Pulmonary Hypertension
Researchers: Elizabeth A. Barnes, Reiji Ito, Xibing Che, Chihhsin Chen, Sushma Reddy, and David N. Cornfield
In addition to the loss of PHD1 and PHD2 being protective in the heart, the loss of PHD1 and PHD2 in the lungs is protective regarding the development of PH in a hypoxia-induced mouse model. This is likely due to an increase in HIF-1a activity promoting angiogenesis.
Pulmonary arterial pressures are increased in WT mice, but not in mice devoid of SMC-PHD1 and PHD2 under chronic hypoxic conditions.
PASMC Stably-expressing HIF-1a Maintain a Cell Survival Advantage
Researchers: Elizabeth A. Barnes, Reiji Ito, David N. Cornfield
HIF-1a is a transcription factor that regulates over 100 genes involved in metabolism, angiogenesis, cell proliferation, cell survival, etc. We have created PASMC that stably-express HIF-1a and preliminary studies show that these cells have a cell survival advantage over WT cells.
Cells stably-expressing HIF-1a are more proliferative as compared to WT PASMC. Magnification 630x. Expression of phospho-histone H3 (green) and nuclei (blue) are pictured. Phospho-histone H3 is a cell cycle marker for cells that are actively dividing.
The Influence of PHD Co-factors in the Development of Hypoxia-induced Pulmonary Hypertension in Mice
Researchers: Elizabeth A. Barnes and David N. Cornfield
PHD proteins need several co-factors to maintain optimal activity, including Fe(II), O2, ascorbate, and 2-oxoglutarate. We have found that PH PAEC and PASMC react differently when exposed to various PHD co-factors, suggesting that the manipulation of these co-factors may alter HIF-1a activity in the development of PH.
The SM22a-PHD1/2-/- Heart
Researchers: Elizabeth A. Barnes, David N. Cornfield
The loss of PHD1 and PHD2 (prolyl hydroxylase domain) proteins in the mouse heart leads to an increase in cardiac microvessels. PHD proteins degrade HIF-1a, a major component of angiogenesis. Without SMC-PHD1 and PHD2 present, HIF-1a remains stable and is transcriptionally active. The increase in microvessels likely plays a protective role in the heart.
PHD1/2+/+ (wild-type, WT) heart (left panel) and PHD1/2-/- heart (right panel). Only the PHD1/2-/- heart remains functional ex vivo.
People
Elizabeth A. Barnes, Ph.D.
Chihhsin Chen, M.S.
Xibing Che, Ph.D.
David N. Cornfield, M.D.
Reiji Ito, M.D., Ph.D.
