TY - JOUR
T1 - Gap junctions mediate STAT5-independent β-casein expression in CID-9 mammary epithelial cells
AU - Talhouk, Rabih S.
AU - Khalil, Antoine A.
AU - Bajjani, Rachid
AU - Rahme, Gilbert J.
AU - El-Sabban, Marwan E.
PY - 2011/10
Y1 - 2011/10
N2 - Crosstalk between gap junction intracellular communication (GJIC), STAT5 and OCT-1 in gap junction (GJ)-dependent β-casein expression was investigated. CID-9 mammary cells plated with prolactin on non-adherent substratum (poly-HEMA) expressed β-casein independent of STAT5 only in the presence of the GJIC inducer, cAMP. Nuclear STAT5 levels were not detectable. By contrast, cells on EHS-drip expressed β-casein in a STAT5-dependent manner and nuclear STAT5 levels were up-regulated. A 75 kDa OCT-1 isoform was detected in conditions that induced β-casein expression regardless of substratum. Interestingly, 40 and 28 kDa OCT-1 isoforms were induced in cells on polyHEMA with cAMP. Electrophoretic mobility shift assays (EMSA) for OCT-1 revealed two band shifts in cells on polyHEMA with cAMP and on EHS-drip, which were repressed by the GJIC inhibitor, 18α-GA. These studies demonstrated that mammary cells on polyHEMA expressed β-casein in response to prolactin in a pathway that involves GJIC and OCT-1 and is independent of STAT5 nuclear translocation.
AB - Crosstalk between gap junction intracellular communication (GJIC), STAT5 and OCT-1 in gap junction (GJ)-dependent β-casein expression was investigated. CID-9 mammary cells plated with prolactin on non-adherent substratum (poly-HEMA) expressed β-casein independent of STAT5 only in the presence of the GJIC inducer, cAMP. Nuclear STAT5 levels were not detectable. By contrast, cells on EHS-drip expressed β-casein in a STAT5-dependent manner and nuclear STAT5 levels were up-regulated. A 75 kDa OCT-1 isoform was detected in conditions that induced β-casein expression regardless of substratum. Interestingly, 40 and 28 kDa OCT-1 isoforms were induced in cells on polyHEMA with cAMP. Electrophoretic mobility shift assays (EMSA) for OCT-1 revealed two band shifts in cells on polyHEMA with cAMP and on EHS-drip, which were repressed by the GJIC inhibitor, 18α-GA. These studies demonstrated that mammary cells on polyHEMA expressed β-casein in response to prolactin in a pathway that involves GJIC and OCT-1 and is independent of STAT5 nuclear translocation.
KW - β-casein
KW - GJIC
KW - OCT-1
KW - STAT5
UR - http://www.scopus.com/inward/record.url?scp=83255176107&partnerID=8YFLogxK
U2 - 10.3109/15419061.2011.639468
DO - 10.3109/15419061.2011.639468
M3 - Article
C2 - 22142338
AN - SCOPUS:83255176107
SN - 1541-9061
VL - 18
SP - 104
EP - 116
JO - Cell Communication and Adhesion
JF - Cell Communication and Adhesion
IS - 5
ER -