Fibroblast Heterogeneity of Signal Transduction Mechanisms to Complement-C1q. Analyses of Calcium Mobilization, Inositol Phosphate Accumulation, and Protein Kinases-C Redistribution

Fibroblasts of healthy and granulation gingiva are phenotypically heterogeneous with regard to binding Clq collagen-like (cClqR) or Clq globular-heads (gClqR) regions, respectively. Here, isolated fibroblast subsets, expressing either the cClqR or the gClqR phenotype, were stimulated with Clq, and assessed for changes in cytosolic free calcium [Ca2+]i, accumulation of inositol trisphosphate (IP3), and redistribution of Ca2+-dependent protein kinases-C (cPKCs) from cytosol to membranes. Changes in [Ca2+]i were determined using Indo-1 fluorescence in combination with adhering cell analysis and sorting (ACAS) cytometry. Accumulation of IP3 was quantified using a competitive radioreceptor binding assay. Redistribution of cPKCs was evaluated by immunoblotting with antibodies to PKCa/βI-βII/γ. Subsets manifested different fluctuations in [Ca2+]i levels 20 seconds after C1q-stimulation in the presence of millimolar concentrations of external calcium. Whereas cC1qR fibroblasts responded with a 38% over baseline [...