scholarly journals Bradykinin B2 Receptor-Mediated Mitogen-Activated Protein Kinase Activation in COS-7 Cells Requires Dual Signaling via Both Protein Kinase C Pathway and Epidermal Growth Factor Receptor Transactivation

1999 ◽  
Vol 19 (8) ◽  
pp. 5289-5297 ◽  
Author(s):  
Antje Adomeit ◽  
Angela Graness ◽  
Steffen Gross ◽  
Klaus Seedorf ◽  
Reinhard Wetzker ◽  
...  
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Egf Receptor ◽  
Mitogen Activated Protein Kinase ◽  
Kinase C ◽  
Pkc Isoforms ◽  
Mitogen Activated Protein ◽  
Epidermal Growth ◽  
Pkc Activation ◽  
Receptor Transactivation

ABSTRACT The signaling routes linking G-protein-coupled receptors to mitogen-activated protein kinase (MAPK) may involve tyrosine kinases, phosphoinositide 3-kinase γ (PI3Kγ), and protein kinase C (PKC). To characterize the mitogenic pathway of bradykinin (BK), COS-7 cells were transiently cotransfected with the human bradykinin B2receptor and hemagglutinin-tagged MAPK. We demonstrate that BK-induced activation of MAPK is mediated via the α subunits of a Gq/11 protein. Both activation of Raf-1 and activation of MAPK in response to BK were blocked by inhibitors of PKC as well as of the epidermal growth factor (EGF) receptor. Furthermore, in PKC-depleted COS-7 cells, the effect of BK on MAPK was clearly reduced. Inhibition of PI3-Kγ or Src kinase failed to diminish MAPK activation by BK. BK-induced translocation and overexpression of PKC isoforms as well as coexpression of inactive or constitutively active mutants of different PKC isozymes provided evidence for a role of the diacylglycerol-sensitive PKCs α and ɛ in BK signaling toward MAPK. In addition to PKC activation, BK also induced tyrosine phosphorylation of EGF receptor (transactivation) in COS-7 cells. Inhibition of PKC did not alter BK-induced transactivation, and blockade of EGF receptor did not affect BK-stimulated phosphatidylinositol turnover or BK-induced PKC translocation, suggesting that PKC acts neither upstream nor downstream of the EGF receptor. Comparison of the kinetics of PKC activation and EGF receptor transactivation in response to BK also suggests simultaneous rather than consecutive signaling. We conclude that in COS-7 cells, BK activates MAPK via a permanent dual signaling pathway involving the independent activation of the PKC isoforms α and ɛ and transactivation of the EGF receptor. The two branches of this pathway may converge at the level of the Ras-Raf complex.

scholarly journals The m3 muscarinic acetylcholine receptor is coupled to mitogen-activated protein kinase via protein kinase C and epidermal growth factor receptor kinase

2000 ◽  
Vol 348 (2) ◽  
pp. 381-387 ◽  
Author(s):  
Barbara E. SLACK
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Egf Receptor ◽  
Mitogen Activated Protein Kinase ◽  
Negative Feedback Regulation ◽  
Kinase C ◽  
Mitogen Activated Protein ◽  
M3 Receptor

The acetylcholine analogue carbachol rapidly activated mitogen-activated protein kinase (MAPK), and caused tyrosine phosphorylation of the adapter protein p52 Shc and the epidermalgrowth factor (EGF) receptor, in human embryonic kidney cells stably expressing m3 muscarinic receptors. The protein kinase C (PKC) inhibitor GF109203X caused a significant partial inhibition of m3 receptor-mediated activation of MAPK. The PKC-independent MAPK activity elicited by carbachol in the presence of GF109203X was reproducibly abolished by AG1478, an inhibitor of EGF-receptor tyrosine kinase activity, and by the Src tyrosine kinase inhibitor PP1. In a subset of these experiments, GF109203X concomitantly increased carbachol-induced tyrosine phosphorylation of p52 Shc and the EGF receptor. In co-stimulation experiments, carbachol and EGF activated MAPK in a non-additive fashion; moreover, EGF-induced association of Shc with the phosphorylated EGF receptor was inhibited by carbachol. This effect of carbachol was blocked by GF109203X. The results indicate that MAPK activation by m3 receptor stimulation is regulated by two pathways; one dependent on PKC, and the other mediated via the EGF receptor and Src. Moreover, the EGF-receptor-dependent pathway may be subject to negative-feedback regulation via m3 receptor-coupled activation of PKC.

scholarly journals Role for Phospholipase D in Receptor-Mediated Endocytosis

2001 ◽  
Vol 21 (2) ◽  
pp. 595-602 ◽  
Author(s):  
Yingjie Shen ◽  
Lizhong Xu ◽  
David A. Foster
Keyword(s):  
Protein Kinase ◽  
Phospholipase D ◽  
Egf Receptor ◽  
Mitogen Activated Protein Kinase ◽  
Wild Type ◽  
Receptor Endocytosis ◽  
Kinase C ◽  
Mitogen Activated Protein ◽  
Epidermal Growth ◽  
Lag Period

ABSTRACT In response to epidermal growth factor (EGF), the EGF receptor is endocytosed and degraded. A substantial lag period exists between endocytosis and degradation, suggesting that endocytosis is more than a simple negative feedback. Phospholipase D (PLD), which has been implicated in vesicle formation in the Golgi, is activated in response to EGF and other growth factors. We report here that EGF receptor endocytosis is dependent upon PLD and the PLD1 regulators, protein kinase C α and RalA. EGF-induced receptor degradation is accelerated by overexpression of either wild-type PLD1 or PLD2 and retarded by overexpression of catalytically inactive mutants of either PLD1 or PLD2. EGF-induced activation of mitogen-activated protein kinase, which is dependent upon receptor endocytosis, is also dependent upon PLD. These data suggest a role for PLD in signaling that facilitates receptor endocytosis.

Targeted degradation of ENaC in response to PKC activation of the ERK1/2 cascade

2003 ◽  
Vol 284 (5) ◽  
pp. F938-F947 ◽  
Author(s):  
Rachell E. Booth ◽  
James D. Stockand
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Actinomycin D ◽  
Mitogen Activated Protein Kinase ◽  
Extracellular Signal Regulated Kinase ◽  
Kinase C ◽  
Extracellular Signal ◽  
Pkc Signaling ◽  
Mitogen Activated Protein ◽  
Pkc Activation

Renal A6 epithelial cells were used to determine the mechanism by which protein kinase C (PKC) decreases epithelial Na+ channel (ENaC) activity. Activation of PKC reduced relative Na+ reabsorption to <20% within 60 min. This decrease was sustained over the next 24–48 h. In response to PKC signaling, α-, β-, and γ-ENaC levels were 0.97, 0.36, and 0.39, respectively, after 24 h, with the levels of the latter two subunits being significantly decreased. The PKC-mediated decreases in β- and γ-ENaC were significantly reversed by simultaneous addition of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase-1/2 inhibitors U-0126 and PD-98059. These inhibitors, in addition, protected Na+ reabsorption from PKC, demonstrating that the MAPK1/2 cascade, in some instances, plays a central role in downregulation of ENaC activity. The effects of PKC on β- and γ-ENaC levels were additive with those of inhibitors of transcription (actinomycin D) and translation (emetine and cycloheximide), suggesting that PKC promotes subunit degradation and does not affect subunit synthesis. The bulk of whole cell γ-ENaC was degraded within 1 h after treatment with inhibitors of synthesis; however, a significant pool was “protected” from inhibitors for up to 12 h. PKC affected this protected pool of γ-ENaC. Moreover, proteosome inhibitors (MG-132 and lactacystin) reversed PKC effects on this protected pool of γ-ENaC. Thus PKC signaling via MAPK1/2 cascade activation in A6 cells promotes degradation of γ-ENaC.

Sign in / Sign up

Export Citation Format

Share Document