Putative role for EPC-1/PEDF in the G0 growth arrest of human diploid fibroblasts.
EPC-1/PEDF expression is closely associated with reversible growth arrest in normal human diploid fibroblast-like (HDF) cells and is diminished with proliferative senescence in vitro. EPC-1 expression in HDF cells is induced under conditions of density-dependent contact inhibition and growth factor deprivation. Antiserum generated against EPC-1 recognizes a secreted protein of approximately 50 kDa from medium conditioned by early passage HDF cells, but not from senescent cells. The addition of EPC-1 antiserum to early population doubling level (PDL) cultures near the plateau phase of growth significantly increases the number of cells entering DNA synthesis. Affinity purified EPC-1 antibodies alone enhance the ability of near plateau-phase early PDL WI-38 cells to synthesize DNA by as much as threefold. Further, the addition of recombinant EPC-1 (rEPC-1) to logarithmically growing cells resulted in a marked decrease in the ability of these cells to enter DNA synthesis. We also demonstrate the loss of EPC-1 expression in WI-38 and IMR-90 HDF cell lines with both senescence and simian virus 40 (SV40) transformation. The loss of EPC-1 expression with SV40 transformation occurs at the level of steady-state mRNA and protein accumulation with genomic EPC-1 sequences grossly intact. Taken together, these results suggest that EPC-1 may play a role in the entry of early passage fibroblasts into a G(0) state or the maintenance of such a state once reached.
Pignolo
Robert J
RJ
Center for Gerontological Research, Medical College of Pennsylvania, Philadelphia, Pennsylvania, USA.
Francis
Mary Kay
MK
Rotenberg
Mitch O
MO
Cristofalo
Vincent J
VJ
D000906:Antibodies / Q000494:pharmacology; D015152:Blotting, Northern; D015153:Blotting, Western; D002455:Cell Division / Q000502:physiology; D002460:Cell Line; D002461:Cell Line, Transformed; D016922:Cellular Senescence / Q000502:physiology; D017077:Culture Media, Conditioned / Q000737:chemistry / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis; D004171:Diploidy; D005136:Eye Proteins; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006133:Growth Substances / Q000494:pharmacology; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology; D009414:Nerve Growth Factors; D011506:Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology; D016192:Resting Phase, Cell Cycle / Q000502:physiology*; D015843:Serpins / Q000378:metabolism* / Q000494:pharmacology; D013539:Simian virus 40; D000099174:Pigment Epithelium-Derived Factor
D000906:Antibodies; D017077:Culture Media, Conditioned; D004247:DNA; D005136:Eye Proteins; D006133:Growth Substances; D007106:Immune Sera; D009414:Nerve Growth Factors; D011506:Proteins; D011994:Recombinant Proteins; D015843:Serpins; D000099174:Pigment Epithelium-Derived Factor