FIBROBLAST HETEROGENEITY OF SIGNAL-TRANSDUCTION MECHANISMS TO COMPLEMENT-C1Q - ANALYSES OF CALCIUM MOBILIZATION, INOSITOL PHOSPHATE ACCUMULATION, AND PROTEIN-KINASE-C REDISTRIBUTION
S. Bordin et al., FIBROBLAST HETEROGENEITY OF SIGNAL-TRANSDUCTION MECHANISMS TO COMPLEMENT-C1Q - ANALYSES OF CALCIUM MOBILIZATION, INOSITOL PHOSPHATE ACCUMULATION, AND PROTEIN-KINASE-C REDISTRIBUTION, Journal of periodontology, 69(6), 1998, pp. 642-649
FIBROBLASTS OF HEALTHY AND GRANULATION gingiva are phenotypically hete
rogeneous with regard to binding Clq collagen-like (cClqR) or Clq glob
ular-heads (gClqR) regions, respectively. Here, isolated fibroblast su
bsets, expressing either the cClqR or the gClqR phenotype, were stimul
ated with Clq, and assessed for changes in cytosolic free calcium [Ca2
+](i), accumulation of inositol trisphosphate (IP3), and redistributio
n of Ca2+-dependent protein kinases-C (cPKCs) from cytosol to membrane
s. Changes in [Ca2+], were determined using Indo-1 fluorescence in com
bination with adhering cell analysis and sorting (ACAS) cytometry. Acc
umulation of IP3 was quantified using a competitive radioreceptor bind
ing assay. Redistribution of cPKCs was evaluated by immunoblotting wit
h antibodies to PKC alpha/beta I-beta II/gamma. Subsets manifested dif
ferent fluctuations in [Ca2+](i) levels 20 seconds after Clq-stimulati
on in the presence of millimolar concentrations of external calcium. W
hereas cClqR fibroblasts responded with a 38% over baseline [Ca2+](i)
increase which was sustained for 20 to 30 minutes, gClqR fibroblasts r
esponded with a higher (264% over baseline) and more rapid (2 to 3 min
utes) transient. Likewise, subsets exhibited different kinetics of IP3
accumulation. Whereas cClqR fibroblasts responded with an IP3 increas
e of 32 +/- 3 pmol/10(4) cells over baseline after 5 seconds stimulati
on, gClqR fibroblasts responded after 15 to 20 seconds with a lower in
crease (13 +/- 0.8 IP3 pmol/10(4) cells over baseline). Subsets differ
ed in cPKCs redistribution which peaked in gClqR-membranes 30 seconds
after stimulation and remained sustained between 10 and 30 minutes. No
cPKC redistribution was detectable in stimulated cClqR-cells. We conc
lude that fibroblasts are heterogeneous in phosphoinositide-Ca2+ signa
ling and cPKC redistribution to Clq, and suggest that these difference
s may affect activities of normal and granulation gingiva.