Calcium mobilisation modulates growth of lens cells.
The modulating effect of calcium cell signalling agonists on tissue growth was studied in a rabbit lens cell line (NN1003A). Calcium mobilisation was measured after Fura-2 incorporation and growth assayed either by direct Coulter counting or [3H]-thymidine incorporation. Transient increases in cytoplasmic calcium were elicited by rabbit serum, histamine, ATP and PDGF. Thapsigargin induced a prolonged increase and all of the above agonists failed to elicit a response after thapsigargin. Rabbit serum and PDGF both increased cell growth in a concentration-dependent manner. While histamine and ATP had little effect in serum-free medium, they reduced serum-stimulated growth. Acetylcholine and FGF did not produce a marked rise in cytoplasmic calcium and neither did they modulate growth. Both thapsigargin and caffeine greatly inhibited growth. These findings indicate that, in lens cells, agonists that mobilise calcium, whether by acting through G-protein or tyrosine kinase receptors, also modulate lens cell growth. Agents such as thapsigargin and caffeine that inactivate the same calcium store also inhibit growth.
Duncan
G
G
School of Biological Science, University of East Anglia, Norwich, UK.
Riach
R A
RA
Williams
M R
MR
Webb
S F
SF
Dawson
A P
AP
Reddan
J R
JR
D000109:Acetylcholine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002460:Cell Line / Q000166:cytology / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005346:Fibroblast Growth Factors / Q000494:pharmacology; D016257:Fura-2; D006131:Growth Inhibitors / Q000494:pharmacology; D007908:Lens, Crystalline / Q000166:cytology* / Q000378:metabolism; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011817:Rabbits; D013729:Terpenes / Q000494:pharmacology; D019284:Thapsigargin
D004791:Enzyme Inhibitors; D006131:Growth Inhibitors; D010726:Phosphodiesterase Inhibitors; D010982:Platelet-Derived Growth Factor; D013729:Terpenes; D002110:Caffeine; D005346:Fibroblast Growth Factors; D019284:Thapsigargin; D000255:Adenosine Triphosphate; D000109:Acetylcholine; D002118:Calcium; D016257:Fura-2