A decreased Ca2+-wave propagation is found among cultured RPE cells from dystrophic RCS rats.
OBJECTIVE
The authors investigated intercellular communication among cultured rat retinal pigment epithelial (RPE) cells isolated from dystrophic Royal College of Surgeons (RCS) rats by studying the conduction of the [Ca2+]i wave elicited by mechanical stimulation. The effect of protein phosphorylation was measured by modulating the protein kinase C (PKC), protein kinase A (PKA), and tyrosine kinase activity.


METHODS
Cultured RPE cells isolated from neonatal control Long-Evans (LE) and dystrophic RCS rats were analyzed using the fluorescent dye fluo-3 to measure the Ca2+-wave propagation on mechanical stimulation to investigate the intercellular communication.


RESULTS
Mechanical stimulation in LE-RPE cells resulted in a centrifugally spreading Ca2+ wave through the neighboring cells. When a mechanical stimulus was applied on RCS-RPE cells, a significantly reduced Ca2+-response was found in the neighboring cells compared with that of control RPE cells. Activation of PKC almost completed blocked the mechanically induced Ca2+ rise in the neighboring RCS-RPE cells. In contrast to LE-RPE cells, an activation of PKA also significantly decreased the Ca2+-wave propagation in RCS-RPE cells. Inhibition of PKA had no effect on the intercellular communication in LE- or RCS-RPE cells. In addition, when protein phosphatase activity or tyrosine kinase activity was inhibited, an increased Ca2+ rise in the neighboring cells on mechanical stimulation was measured, reaching levels currently found for LE-RPE cells.


CONCLUSIONS
In dystrophic RCS-RPE cells, a decreased intercellular Ca2+-wave propagation is found. This intercellular communication can be mediated by protein phosphorylation.
Stalmans
P
P
Laboratory of Physiology, KU Leuven, Belgium.
Himpens
B
B
D000814:Aniline Compounds / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002450:Cell Communication / Q000502:physiology; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000378:metabolism; D019319:Okadaic Acid / Q000494:pharmacology; D010766:Phosphorylation; D010857:Pigment Epithelium of Eye / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D011922:Rats, Mutant Strains; D012162:Retinal Degeneration / Q000378:metabolism*; D013314:Stress, Mechanical; D019284:Thapsigargin / Q000494:pharmacology; D014966:Xanthenes / Q000378:metabolism
D000814:Aniline Compounds; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D014966:Xanthenes; D019319:Okadaic Acid; C059715:Fluo-3; D019284:Thapsigargin; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D000252:Calcium-Transporting ATPases; D002118:Calcium