Adenovirus-mediated overexpression of diacylglycerol kinase-zeta inhibits endothelin-1-induced cardiomyocyte hypertrophy.
BACKGROUND
Diacylglycerol (DAG) is a lipid second messenger that transiently accumulates in cells stimulated by endothelin-1 (ET-1) and other Galphaq protein-coupled receptor agonists. Diacylglycerol kinase (DGK) is thought to be an enzyme that controls the cellular levels of DAG by converting it to phosphatidic acid; however, the functional role of DGK has not been examined in cardiomyocytes. Because DGK inactivates DAG, a strong activator of protein kinase C (PKC), we hypothesized that DGK inhibited ET-1-induced activation of a DAG-PKC signaling cascade and subsequent cardiomyocyte hypertrophy.


RESULTS
Real-time reverse transcription-polymerase chain reaction demonstrated a significant increase of DGK-zeta mRNA by ET-1 in cardiomyocytes. To determine the functional role of DGK-zeta, we overexpressed DGK-zeta in cardiomyocytes using a recombinant adenovirus encoding rat DGK-zeta (Ad-DGKzeta). ET-1-induced translocation of PKC-epsilon was blocked by Ad-DGKzeta (P<0.01). Ad-DGKzeta also inhibited ET-1-induced activation of extracellular signal-regulated kinase (P<0.01). Luciferase reporter assay revealed that ET-1-mediated increase of activator protein-1 (AP1) DNA-binding activity was significantly inhibited by DGK-zeta (P<0.01). In cardiomyocytes transfected with DGK-zeta, ET-1 failed to cause gene induction of atrial natriuretic factor, increases in [3H]-leucine uptake, and increases in cardiomyocyte surface area.


CONCLUSIONS
We demonstrated for the first time that DGK-zeta blocked ET-1-induced activation of the PKC-epsilon-ERK-AP1 signaling pathway, atrial natriuretic factor gene induction, and resultant cardiomyocyte hypertrophy. DGK-zeta might act as a negative regulator of hypertrophic program in response to ET-1, possibly by controlling cellular DAG levels.
Takahashi
Hiroki
H
First Department of Internal Medicine, Yamagata University School of Medicine, Yamagata, Japan.
Takeishi
Yasuchika
Y
Seidler
Tim
T
Arimoto
Takanori
T
Akiyama
Hideyuki
H
Hozumi
Yasukazu
Y
Koyama
Yo
Y
Shishido
Tetsuro
T
Tsunoda
Yuichi
Y
Niizeki
Takeshi
T
Nozaki
Naoki
N
Abe
Jun-ichi
J
Hasenfuss
Gerd
G
Goto
Kaoru
K
Kubota
Isao
I
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000235:genetics; D049108:Cell Enlargement / Q000187:drug effects*; D002478:Cells, Cultured; D019852:Diacylglycerol Kinase / Q000235:genetics / Q000502:physiology*; D004075:Diglycerides / Q000378:metabolism; D019332:Endothelin-1 / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D005786:Gene Expression Regulation; D006984:Hypertrophy / Q000209:etiology* / Q000473:pathology; D032383:Myocytes, Cardiac / Q000378:metabolism / Q000473:pathology*; D011493:Protein Kinase C / Q000378:metabolism; D051744:Protein Kinase C-epsilon; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D015290:Second Messenger Systems; D015533:Transcriptional Activation; D014161:Transduction, Genetic
D004075:Diglycerides; D019332:Endothelin-1; D012333:RNA, Messenger; D009320:Atrial Natriuretic Factor; C497257:Prkce protein, rat; D019852:Diacylglycerol Kinase; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon