Prolactin stimulates the proliferation of normal female cholangiocytes by differential regulation of Ca2+-dependent PKC isoforms.
BACKGROUND
Prolactin promotes proliferation of several cells. Prolactin receptor exists as two isoforms: long and short, which activate different transduction pathways including the Ca2+-dependent PKC-signaling. No information exists on the role of prolactin in the regulation of the growth of female cholangiocytes. The rationale for using cholangiocytes from female rats is based on the fact that women are preferentially affected by specific cholangiopathies including primary biliary cirrhosis. We propose to evaluate the role and mechanisms of action by which prolactin regulates the growth of female cholangiocytes.


RESULTS
Normal cholangiocytes express both isoforms (long and short) of prolactin receptors, whose expression increased following BDL. The administration of prolactin to normal female rats increased cholangiocyte proliferation. In purified normal female cholangiocytes, prolactin stimulated cholangiocyte proliferation, which was associated with increased [Ca2+]i levels and PKCbeta-I phosphorylation but decreased PKCalpha phosphorylation. Administration of an anti-prolactin antibody to BDL female rats decreased cholangiocyte proliferation. Normal female cholangiocytes express and secrete prolactin, which was increased in BDL rats. The data show that prolactin stimulates normal cholangiocyte growth by an autocrine mechanism involving phosphorylation of PKCbeta-I and dephosphorylation of PKCalpha.


CONCLUSIONS
We suggest that in female rats: (i) prolactin has a trophic effect on the growth of normal cholangiocytes by phosphorylation of PKCbeta-I and dephosphorylation of PKCalpha; and (iii) cholangiocytes express and secrete prolactin, which by an autocrine mechanism participate in regulation of cholangiocyte proliferation. Prolactin may be an important therapeutic approach for the management of cholangiopathies affecting female patients.
Taffetani
Silvia
S
Department of Gastroenterology, Università Politecnica delle Marche, Nuovo Polo Didattico, III piano, Ancona, Italy. taffetanisilvia@yahoo.it <taffetanisilvia@yahoo.it>
Glaser
Shannon
S
Francis
Heather
H
DeMorrow
Sharon
S
Ueno
Yoshiyuki
Y
Alvaro
Domenico
D
Marucci
Luca
L
Marzioni
Marco
M
Fava
Giammarco
G
Venter
Julie
J
Vaculin
Shelley
S
Vaculin
Bradley
B
Lam
Ian Pak-Yan
IP
Lee
Vien Hoi-Yi
VH
Gaudio
Eugenio
E
Carpino
Guido
G
Benedetti
Antonio
A
Alpini
Gianfranco
G
D000818:Animals; D001652:Bile Ducts / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D010766:Phosphorylation; D011388:Prolactin / Q000378:metabolism* / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344; D011981:Receptors, Prolactin / Q000096:biosynthesis
D007527:Isoenzymes; D011981:Receptors, Prolactin; D011388:Prolactin; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha