cAMP stimulation of PRKX-dependent CRE promoter elements, detections of
PRKX–RI holoenzyme complexes, and nuclear translocation of EGFP/PRKX
fusion protein. (A) Five micrograms of PRKX expression
construct cotransfected with 3 μg of pCRE-luciferase into JAR cells
incubated in the presence or absence of 1 μM 8-Br-cAMP or 1 μM H89
followed by luciferase activity assay 24 h after transfection. The
letters on the abscissa refer to constructs used for cell transfection
(L, CRE-luciferase promoter-reporter; V, empty expression vector; PRKX,
pFLAG/PRKX; PKA, pFC-PKA). All values are means ± SEM for two
separate transfection experiments carried out in triplicate.
(B) PKRX–RI complexes were detected by
immunoprecipitation experiments of PRKX-transfected cells. PRKX/T (+,
−) indicates cell transfection with pFLAG/PRKX. IP (+, −) indicates
immunoprecipitation with anti-FLAG antibody beads. Lanes 1 and 2
(Left and Right) and lanes 1 and 3
(Middle) represent immunoblots performed on whole-cell
lysates. Lanes 3 and 4 (Left and Right)
and lanes 2 and 4 (Middle) are immunoblots performed on
anti-FLAG immunoprecipitated proteins. (C)
cAMP-dependent PRKX nuclear translocation demonstrated in FIB4 cells
transfected with pEGFP/PRKX and treated with 100 μM 8-Br-cAMP for
0, 1, 3, 5, 10, 15, 30, and 120 min.