20-Hydroxyeicosatetraenoic acid is formed in response to EGF and is a mitogen in rat proximal tubule

Abstract

Hydroxyeicosatetraenoic acid (20-HETE) is a major cytochrome P-450-arachidonic acid metabolite in the rat kidney, and its synthesis along the nephron is specifically localized to the proximal tubule, where receptor density for epidermal growth factor (EGF) is the highest. EGF stimulated endogenous 20-HETE formation in a concentration and time-dependent manner, i.e., from 1.6 to 2.6 +/- 0.3 and 3.0 +/- 0.6 pmol 20-HETE.mg-1.min-1 at 10(-8) and 10(-7) M EGF, respectively. The effect of 20-HETE on proximal tubular cell proliferation was examined using primary cultures of rat proximal tubular cells and proximal tubular-derived cell lines, LLC-PK1 and opossum kidney OK. In both cell lines, 20-HETE increased thymidine incorporation into DNA with maximal effect at 10(-9) M. Addition of 20-HETE to serum-deprived LLC-PK1 or OK cells for 48 h caused a concentration-dependent increase in cell number with maximal effect at 10(-9) M. This effect was specific, as structurally similar eicosanoids such as 20-COOH-arachidonic acid, 19(R)-HETE, and 19(S)-HETE did not increase cell number. In 4-day primary cultures of proximal tubular cells, EGF (10(-9) M) and 20-HETE (10(-9) M) increased bromodeoxyuridine (BrdU) incorporation by 40 and 28%, respectively. Addition of both resulted in a twofold increase in BrdU incorporation. Although 20-HETE synthesis in cultured cells is greatly diminished with time, significant picomolar concentrations can be obtained in 4-day cultures. Addition of 17-octadecynoic acid (17-ODYA), an inhibitor of 20-HETE synthesis, significantly inhibited EGF-stimulated BrdU incorporation. The demonstrations that EGF stimulates proximal tubular 20-HETE production and that the latter is a potent mitogen to these cells suggests that 20-HETE may act as a mediator of the EGF effect on cellular growth in the proximal tubule.

Elevated production of 20-HETE in the cerebral vasculature contributes to severity of ischemic stroke and oxidative stress in spontaneously hypertensive rats

“…20-HETE has been reported to play an important role in the regulation of cerebral vascular tone by regulating the open state probability of calcium-activated potassium channels (32). It also promotes the formation of oxygen radicals (15,16,20,33,36,59) and contributes to endothelial dysfunction (35,42,45,49,62). More recently, inhibitors of the synthesis of 20-HETE have been reported to reverse the fall in cerebral blood flow (CBF) following subarachnoid hemorrhage (SAH) (3,21,28,35,55) and reduce infarct size following transient cerebral ischemia (35,42,45,57).…”

20-HETE activates the Raf/MEK/ERK pathway in renal epithelial cells through an EGFR- and c-Src-dependent mechanism

“…epithelial cell proliferation; epidermal growth factor receptor; cell signaling 20-HYDROXYEICOSATETRAENOIC acid (20-HETE) is a lipid metabolite of arachidonic acid that is produced by -hydroxylase enzymes of the cytochrome P-450 4A (CYP4A) and 4F families (21). 20-HETE has long been known to play an integral role in the regulation of renal function, including renal vascular tone (14), tubuloglomerular feedback (49), autoregulation of renal blood flow (12,13,48), tubular transport (6,30,38,45), and mitogenesis (4,18,23,44).There has been renewed interest in 20-HETE because of its potential as a novel therapeutic target in the treatment of acute kidney injury (32), cancer (8 -10), and polycystic kidney disease (PKD) (28,29). Regner et al (32) showed that acute administration of a 20-HETE mimetic resulted in increased renal protection following ischemia-reperfusion injury.…”

Cytochrome P450 4A Isoform Inhibitory Profile of N-Hydroxy-N'-(4-butyl-2-methylphenyl)-formamidine (HET0016), a Selective Inhibitor of 20-HETE Synthesis

“…5) A number of studies have demonstrated that 20-HETE has potent biological activities which contribute to the regulation of renal tubular and vascular function and the long-term control of arterial blood pressure. [6][7][8][9][10] 20-HETE is also a potent vasoconstrictor in the cerebral microcirculation and a regulator of vascular tone and autoregulation of cerebral blood flow. [11][12][13][14] On the other hand, EETs have been known as vasodilators and inhibitors of sodium and water transport in the kidney.…”