Neprilysin regulates pulmonary artery smooth muscle cell phenotype through a platelet-derived growth factor receptor-dependent mechanism.

Reduced neprilysin (NEP), a cell surface metallopeptidase, which cleaves and inactivates proinflammatory and vasoactive peptides, predisposes the lung vasculature to exaggerated remodeling in response to hypoxia. We hypothesize that loss of NEP in pulmonary artery smooth muscle cells results in increased migration and proliferation. Pulmonary artery smooth muscle cells isolated from NEP(-/-) mice exhibited enhanced migration and proliferation in response to serum and platelet-derived growth factor, which was attenuated by NEP replacement.

Neprilysin null mice develop exaggerated pulmonary vascular remodeling in response to chronic hypoxia.

Neprilysin is a transmembrane metalloendopeptidase that degrades neuropeptides that are important for both growth and contraction. In addition to promoting carcinogenesis, decreased levels of neprilysin increases inflammation and neuroendocrine cell hyperplasia, which may predispose to vascular remodeling. Early pharmacological studies showed a decrease in chronic hypoxic pulmonary hypertension with neprilysin inhibition.

Pulmonary artery smooth muscle cells from chronically hypoxic neonatal calves retain fetal-like and acquire new growth properties.

Growth properties retained and acquired by immature pulmonary artery (PA) smooth muscle cells (SMC) in vivo after chronic exposure to hypoxia and the mechanisms that regulate hypoxia-induced change in proliferative phenotype are not known. We tested the hypothesis that PA SMC from neonatal calves exposed to hypoxia after birth would both retain fetal-like and acquire new growth characteristics and that these changes would be at least partially dependent on protein kinase C (PKC), a key proproliferative signal transduction pathway. Like fetal cells, PA SMC from hypoxic calves grew faster in the presence and absence of serum and were more responsive to insulin-like growth factor I and platelet-derived growth factor-BB than control neonatal and adult cells.

Pregnancy-stimulated growth of vascular smooth muscle cells: importance of protein kinase C-dependent synergy between estrogen and platelet-derived growth factor.

Dramatic smooth muscle cell (SMC) growth occurs in the uterine artery during pregnancy. The potential for pregnancy-associated growth may also exist at other vascular sites. We tested the hypothesis that increased growth of uterine artery SMC isolated from pregnant (vs.

Autoregulation of endothelin-1 secretion by cultured human keratinocytes via the endothelin B receptor.

We investigated endothelin-1 (ET-1) receptor expression on normal human keratinocytes (HK). We show that HK express the ETB receptor isoform and respond to ET-1 with a 2.7-fold increase in intracellular free calcium.

BQ123, an ETA receptor antagonist, inhibits endothelin-1-mediated proliferation of human pulmonary artery smooth muscle cells.

Endothelin (ET-1) has been shown to be co-mitogenic for vascular smooth muscle cells (SMC) from human systemic arteries. A more modest growth-promoting effect has also been described in SMC from the bovine and porcine pulmonary circulation. Whether ET-1 has mitogenic properties in the human pulmonary circulation, and which ET receptor subtype mediates this response, is unknown.

Cultured human keratinocytes synthesize and secrete endothelin-1.

The human epidermal-melanin unit exists as a complex interplay of cell-cell interactions. Melanocytes synthesize melanin and transfer it to the surrounding keratinocytes, which, in turn, produce factors that affect melanocyte homeostasis, growth, and melanization. Endothelin-1 (ET-1), a vasoconstrictor peptide produced by endothelial cells, has recently been shown to stimulate human melanocyte proliferation and tyrosinase activity.