Mechanical strain-enhanced fetal lung cell proliferation is mediated by phospholipase C and D and protein kinase C

Abstract

The signaling pathways by which intermittent strain (60 cycles/min, 15 min/h) regulates proliferation of mixed fetal rat lung cell in vitro have been investigated. Adenosine 3',5'-cyclic monophosphate (cAMP) content and cAMP-dependent protein kinase (PKA) activity were not affected by strain. The stimulatory effect of strain on DNA synthesis was also not influenced by the cyclic nucleotide-dependent protein kinase inhibitors H-8 or HA-1004, the adenylate cyclase inhibitor SQ-22536, or a PKA inhibitor and cAMP antagonist, adenosine 3',5'-cyclic monophosphothioate (Rp-cAMPS). In contrast, intracellular concentrations of two second messengers, inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG), were dramatically increased after a short period of strain. This increase in second messengers was accompanied by an increased tyrosine phosphorylation of phospholipase C-gamma 1. Phospholipase D activity was also increased by strain. Mechanical strain elicited a shift in the subcellular distribution of PKC activity from cytosol to membranes shortly after the onset of strain. The specific activity of PKC in the membranes increased 6- to 10-fold within 5-15 min and remained increased throughout a 48-h period of intermittent strain. Strain-induced PKC activation and DNA synthesis were blocked by the PKC inhibitors H-7, staurosporine, and calphostin C, as well as by the phospholipase C inhibitor U-73,122. We conclude that mechanical strain of mixed fetal rat lung cells activates phospholipid turnover via phospholipases, followed by PKC activation, which then triggers the downstream events that lead to cell proliferation.

Periodic mechanical stress activates MEK1/2-ERK1/2 mitogenic signals in rat chondrocytes through Src and PLCγ1

“…Phosphorylation of PLCγ1-Tyr 783 plays an important role in the signal transduction of cell proliferation and migration by mediating the downstream signaling proteins, including ERK1/2 (16,22). Husain et al (35) confirmed that activation of PLCγ1 is required for vascular endothelial growth factor receptor-2 (VEGFR-2)-induced endothelial cell proliferation in vitro.…”

“…PLCγ1, as one of the serine threonine kinases of PLC, plays an important role in the signal transduction for the regulation of the cellular mitogenic effects in various types of cells in response to different stimuli, including cyclic mechanical stimulation (19)(20)(21)(22). Liu et al (22) have demonstrated that intermittent mechanical strain enhances the cellular proliferation and phosphorylation of PLCγ1 in fetal lung cells, and the mitogenic response to cyclic mechanical stimulation is mediated by activated PLCγ1.…”

“…Liu et al (22) have demonstrated that intermittent mechanical strain enhances the cellular proliferation and phosphorylation of PLCγ1 in fetal lung cells, and the mitogenic response to cyclic mechanical stimulation is mediated by activated PLCγ1. Src, which shows the activity of tyrosine kinase, has been shown by many investigators to be required for proliferation in some cell types in response to mechanical stimuli (14,23).…”

Trp-Lys-Tyr-Met-Val-D-Met stimulates superoxide generation and killing of Staphylococcus aureus via phospholipase D activation in human monocytes

“…To test the role played by PLC in the peptide-induced PLD activation and superoxide anion formation, we used U-73122, a PI-specific PLC inhibitor [21]. As shown in Figure 5A, preincubation of the cells with U-73122 before the stimulus totally inhibited the peptide-induced intracellular calcium mobilization caused by PI hydrolysis.…”

Injurious ventilatory strategies increase cytokines and c-fos m-RNA expression in an isolated rat lung model.

“…Concurrent with these physiological studies, research over the past decade has shown that mechanotransduction (i.e., the conversion of a mechanical stimulus such as cell deformation into biochemical and molecular alterations) plays a crucial role in determining the structure and function of a number of tissues, including the lung (12)(13)(14). Studies in vitro and in vivo have found that both the degree and the pattern of mechanical stretch are important in determining cell responses (14,15).…”