Vascular endothelial growth factor stimulates rat cholangiocyte proliferation via an autocrine mechanism.
OBJECTIVE
Vascular endothelial growth factor (VEGF) is secreted by several epithelia and modulates cellular functions by autocrine and paracrine mechanisms. The role of VEGF in cholangiocyte pathophysiology is unknown. We evaluated the role of VEGF in the regulation of cholangiocyte proliferation in rats that underwent bile duct ligation.


METHODS
The expression of VEGF-A and VEGF-C and their receptors in cholangiocytes from normal and BDL rats was evaluated. Normal or BDL rats were treated with recombinant-VEGF-A or recombinant-VEGF-C or anti-VEGF antibodies, and proliferation of cholangiocytes was evaluated in situ by morphometry and in vitro by proliferating cell nuclear antigen immunoblots and MTS assay. In vitro, normal rat cholangiocyte cultures were stimulated with r-VEGF-A or r-VEGF-C and proliferation and signal transduction were evaluated.


RESULTS
We found that (1) cholangiocytes express messenger RNA and protein for VEGF-A, VEGF-C, VEGF receptor 2 (VEGFR-2), and VEGF receptor 3 (VEGFR-3) and secrete VEGF; (2) secretion of VEGF and expression of VEGFR-2 and VEGFR-3 increases in BDL cholangiocytes; (3) blocking VEGF in vivo by anti-VEGF-A or anti-VEGF-C antibodies decreases cholangiocyte proliferation; (4) the in vivo administration of r-VEGF-A or r-VEGF-C induces cholangiocyte proliferation in normal rats; and (5) in vitro, VEGF-A increases normal rat cholangiocyte culture proliferation by activation of inositol 1,4,5-triphosphate/Ca2+/protein kinase C alpha and phosphorylation of Src/ERK1/2.


CONCLUSIONS
Cholangiocytes secrete VEGF and express VEGFR-2 and VEGFR-3, all of which are amplified in BDL cholangiocytes. VEGF induces cholangiocyte proliferation by activation of inositol 1,4,5-triphosphate/[Ca2+]i/protein kinase C alpha and phosphorylation of Src/ERK1/2. VEGF mediates the adaptive proliferative response of cholangiocytes to cholestasis.
Gaudio
Eugenio
E
Division of Anatomy, University "La Sapienza," Rome, Italy.
Barbaro
Barbara
B
Alvaro
Domenico
D
Glaser
Shannon
S
Francis
Heather
H
Ueno
Yoshiyuki
Y
Meininger
Cynthia J
CJ
Franchitto
Antonio
A
Onori
Paolo
P
Marzioni
Marco
M
Taffetani
Silvia
S
Fava
Giammarco
G
Stoica
George
G
Venter
Julie
J
Reichenbach
Ramona
R
De Morrow
Sharon
S
Summers
Ryun
R
Alpini
Gianfranco
G
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D019898:Autocrine Communication / Q000502:physiology*; D001652:Bile Ducts / Q000166:cytology* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D022781:Hepatocytes / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008026:Ligation; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D051571:Protein Kinase C-alpha / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D011994:Recombinant Proteins / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000097:blood / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D042582:Vascular Endothelial Growth Factor C / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism; D040321:Vascular Endothelial Growth Factor Receptor-3 / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
D000906:Antibodies; D011994:Recombinant Proteins; D042461:Vascular Endothelial Growth Factor A; D042582:Vascular Endothelial Growth Factor C; C467498:vascular endothelial growth factor A, rat; D015544:Inositol 1,4,5-Trisphosphate; D040301:Vascular Endothelial Growth Factor Receptor-2; D040321:Vascular Endothelial Growth Factor Receptor-3; D019061:src-Family Kinases; D051571:Protein Kinase C-alpha; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium