PI-PLCbeta is involved in the modulation of the proximal tubule Na+-ATPase by angiotensin II.
In previous papers we showed that Ang II increases the proximal tubule Na+-ATPase activity through AT1/PKC pathway [L.B. Rangel, C. Caruso-Neves, L.S. Lara, A.G. Lopes, Angiotensin II stimulates renal proximal tubule Na+-ATPase activity through the activation of protein kinase C. Biochim. Biophys. Acta 1564 (2002) 310-316, L.B.A. Rangel, A.G. Lopes, L.S. Lara, C. Caruso-Neves, Angiotensin II stimulates renal proximal tubule Na+)-ATPase activity through the activation of protein kinase C. Biochim. Biophys. Acta 1564 (2002) 310-316]. In the present paper, we study the involvement of PI-PLCbeta on the stimulatory effect of angiotensin II (Ang II) on the proximal tubule Na+-ATPase activity. Western blotting assays, using a polyclonal antibody for PI-PLCbeta, show a single band of about 150 KDa, which correspond to PI-PLCbeta isoforms. Ang II induces a rapid decrease in PIP2 levels, a PI-PLCbeta substrate, being the maximal effect observed after 30 s incubation. This effect of Ang II is completely abolished by 5 x 10(-8) M U73122, a specific inhibitor of PI-PLCbeta. In this way, the effect of 10(-8) M Ang II on the proximal tubule basolateral membrane (BLM) Na+-ATPase activity is completely abolished by 5 x 10(-8) M U73122. The increase in diacylglycerol (DAG) concentration, an product of PI-PLCbeta, from 0.1 to 10 nM raises the Na+-ATPase activity from 6.1+/-0.2 to 13.1+/-1.8 nmol Pi mg(-1) min(-1). This effect is similar and non-additive to that observed with Ang II. Furthermore, the stimulatory effect of 10 nM DAG is completely reversed by 10(-8) M calphostin C (Calph C), an inhibitor of PKC. Taken together these data indicate that Ang II stimulates the Na+-ATPase activity of proximal tubule BLM through a PI-PLCbeta/PKC pathway.
Rangel
L B A
LB
Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro,CCS Bloco G, 21949-900, Rio de Janeiro, RJ, Brazil.
Lopes
A G
AG
Lara
L S M
LS
Carvalho
T L G
TL
Silva
I V
IV
Oliveira
M M
MM
Einicker-Lamas
M
M
Vieyra
A
A
Nogaroli
L
L
Caruso-Neves
C
C
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D027682:Cation Transport Proteins / Q000378:metabolism*; D004075:Diglycerides / Q000378:metabolism; D004963:Estrenes / Q000378:metabolism; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000201:enzymology*; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism; D043265:Phosphatidylinositol Diacylglycerol-Lyase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011760:Pyrrolidinones / Q000378:metabolism; D013552:Swine
D027682:Cation Transport Proteins; D004075:Diglycerides; D004963:Estrenes; D007527:Isoenzymes; D019269:Phosphatidylinositol 4,5-Diphosphate; D011760:Pyrrolidinones; D000804:Angiotensin II; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D000251:Adenosine Triphosphatases; C021838:sodium-translocating ATPase; D043265:Phosphatidylinositol Diacylglycerol-Lyase