A specific phospholipase C activity regulates phosphatidylinositol levels in lung surfactant of patients with acute respiratory distress syndrome
Lung surfactant (LS) is a lipid-rich material lining the inside of the lungs. It reduces surface tension at the liquid/air interface and thus, it confers protection of the alveoli from collapsing. The surfaceactive component of LS is dipalmitoyl-phosphatidylcholine, while anionic phospholipids such as phosphatidylinositol (PtdIns) and primarily phosphatidylglycerol are involved in the stabilization of the LS monolayer. The exact role of PtdIns in this system is not wellunderstood; however, PtdIns levels change dramatically during the acute respiratory distress syndrome (ARDS) evolution. In this report we present evidence of a phosphoinositide-specific phospholipase C (PI-PLC) activity in bronchoalveolar lavage (BAL) fluid,which may regulate PtdIns levels. Characterization of this extracellular activity showed specificity for PtdIns and phosphatidylinositol 4,5-bisphosphate, sharing the typical substrate concentration-, pH-, and calcium-dependencies with mammalian PI-PLCs. Fractionation of BAL fluid showed that PI-PLC did not co-fractionate with large surfactant aggregates, but it was found mainly in the soluble fraction. Importantly, analysis of BAL samples from control subjects and from patients with ARDS showed that the PI-PLC specific activity was decreased by 4-fold in ARDS samples concurrently with the increase in BAL PtdIns levels. Thus, we have identified for the first time an extracellular PI-PLC enzyme activity that may be acutely involved in the regulation of PtdIns levels in LS.
Showing items related by title, author, creator and subject.
Biochemical and genetic evidence for the presence of multiple phosphatidylinositol- and phosphatidylinositol 4,5-bisphosphate-specific phospholipases C in Tetrahymena Leondaritis, G.; Sarri, T.; Dafnis, I.; Efstathiou, A.; Galanopoulou, D. (2011)Eukaryotic phosphoinositide-specific phospholipases C (PI-PLC) specifically hydrolyze phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2], produce the Ca2+-mobilizing agent inositol 1,4,5-trisphosphate, and regulate ...
Insulin causes a transient induction of proliferation via activation of the PI3-kinase pathway in airway smooth muscle cells Papagianni, M.; Hatziefthimiou, A.; Chachami, G.; Gourgoulianis, K.; Molyvdas, P. A.; Paraskeva, E. (2007)Insulin regulates glucose metabolism and activates cell growth. As the respiratory system is an alternative route for insulin administration in patients with diabetes mellitus, we studied the effect of insulin on rabbit ...
Vlachostergios, P. J.; Papandreou, C. N. (2015)Neuroendocrine prostate carcinoma, either co-present with the local adenocarcinoma disease or as a result of transdifferentiation later in time, was described as one major process of emerging resistance to androgen deprivation ...