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Paxillin-associated focal adhesion involvement in perinatal pulmonary arterial remodelling
Ibrahima Diagne1, Susan M Hall, Shigetoyo Kogaki
1Vascular Biology & Pharmacology Unit, Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK.
Insights
Postnatal development involves actin remodeling and focal adhesion changes in pulmonary arteries. Paxillin, a key focal adhesion protein, showed abnormal remodeling in pulmonary hypertension.
Area of Science:
- Cardiovascular Biology
- Cell Biology
- Neonatal Physiology
Background:
- Pulmonary arterial smooth muscle cells undergo significant actin cytoskeleton remodeling after birth.
- Extracellular matrix deposition follows actin remodeling, suggesting coordinated changes in cell-matrix adhesions.
Purpose of the Study:
- To investigate the expression, localization, and biochemical characteristics of the focal adhesion protein paxillin in pulmonary arteries.
- To determine if cell/matrix adhesions, specifically paxillin, are remodeled during the postnatal period and in pulmonary hypertension.
Main Methods:
- In vivo analysis of porcine pulmonary arteries from normal and pulmonary hypertensive neonatal piglets.
- Treatment with cytochalasin D to assess actin and focal adhesion dynamics.
- Analysis of paxillin isoforms, pI values, and phosphorylation.
- Immunostaining for paxillin expression and localization.
Main Results:
- Cytochalasin D induced actin reduction and decreased paxillin-associated focal adhesions in pulmonary arteries.
- Two paxillin isoforms (60 and 66 kDa) were identified with acidic pI values.
- Postnatal changes (birth to 6 days) included reduced paxillin amount, more acidic pI, and increased phosphorylation.
- Paxillin expression transiently decreased, correlating with actin reduction.
- Pulmonary hypertensive arteries exhibited abnormal paxillin content and remodeling, varying with age.
Conclusions:
- Immediate postnatal spatial reorganization of paxillin-associated focal adhesions occurs.
- Paxillin remodeling is altered in pulmonary hypertensive arteries, indicating a pathological response.
Abstract:
Birth is followed by remodelling of the actin cytoskeleton of pulmonary arterial smooth muscle cells, then by extracellular matrix deposition. Hypothesising that the cell/matrix adhesions would also be remodelled, we investigated the expression, localisation and biochemical characteristics of the focal adhesion protein paxillin in vivo, in vessels from normal and pulmonary hypertensive neonatal piglets. Initially we showed that in intact porcine pulmonary arteries exposed to cytochalasin D there was a reduction filamentous actin accompanied by a reduction in paxillin-associated focal adhesions, similar to that seen in cultured pulmonary arterial smooth muscle cells. Vessels from normal and hypoxic animals were found to have two isoforms of paxillin, of 60 and 66 kDa with pI values of 6.7-4.2. Transient changes occurred during the first 14 days of life. Between birth and 6 days there was a reduction in the amount of both paxillin isoforms, a shift to more acidic pI values and an increase in paxillin phosphorylation. Simultaneously, immunostaining showed a transient reduction in paxillin expression, a change temporally and spatially associated with a previously demonstrated reduction in actin. Findings are consistent with an immediate postnatal spatial reorganisation of paxillin-associated focal adhesions. Paxillin content and remodelling was abnormal in pulmonary hypertensive arteries, the response varying according to postnatal age.