Epidermal growth factor-stimulated phosphoinositide hydrolysis in cultured rat inner medullary collecting tubule cells. Regulation by G protein, calcium, and protein kinase C.

Abstract

Epidermal growth factor (EGF) exhibits specific saturable binding to cultured rat inner medullary collecting tubule cells and stimulates inositol trisphosphate (IP3) production by these cells in a dose-dependent fashion. EGF-stimulated IP3 production is enhanced by GTP-ys or AJF4 and is inhibited by GDPBs or pertussis toxin. Alterations in extracellular Ca2" have no effect on either basal or EGF-stimulated IP3 production. Similarly, treatment with EGTA which decreases cytosolic Ca" is without effect. In contrast, treatment with ionomycin which increases cytosolic Ca2" has no effect on basal IP3 production but enhances the response to EGF. Activation of protein kinase C inhibits IP3 production in response to either EGF or AIF4. These studies demonstrate the occurrence of EGF-stimulated phospholipase C activity in the rat inner medullary collecting duct. Stimulation by EGF is transduced by a pertussis toxinsensitive G protein, unaffected by alterations in extracellular Ca2+, insensitive to a decrement in cytosolic Ca`., enhanced by an increase in cytosolic Ca2+, and inhibited by protein kinase C. (J. Clin.

Insulin-like growth factor I gene expression in isolated rat renal collecting duct is stimulated by epidermal growth factor.

“…The concentration dependence for hEGF-stimulated Ins-P3 production in isolated membranes illustrated in Fig. 1 is similar to that shown by Teitelbaum et al ( 12), who reported a significant increase of Ins-P3 production upon addition of 10-8 M or higher concentrations of EGF to cultured rat inner medullary collecting tubule cells (12 changed for 2 h of incubation in the absence of added peptide (2). Addition of hEGF to suspensions of collecting ducts resulted in a concentration-dependent production of IGF I (Fig.…”

“…One mechanism by which EGF transmits its "signal" across the plasma membrane of renal collecting duct cells is via activation of phospholipase C (12). To establish that the potential exists for EGF signal transduction across the plasma membrane of isolated rat renal collecting duct cells, membranes prepared from collecting duct segments were incubated for 15 s in the absence of added peptide or in the presence of 10-10, 10-8, or 10-6 M hEGF.…”

“…In contrast, in kidney cells the precursor accumulates and is not processed to mature EGF (17,20 liii.-.~~_ age of the extracellular membrane-bound protein by proteases present in the lumen ofthe nephron or in serum would serve to release EGF and account for the large quantity of the peptide present in urine (7) or in medullary interstitium (17,20 (12,21) and in freshly isolated suspensions (22). Teitelbaum et al (12) reported that EGF stimulates phospholipase C activity in cultured rat inner medullary collecting tubule cells (12). Harris (21) (25).…”

Vasopressin resistance in chronic renal failure. Evidence for the role of decreased V2 receptor mRNA.

“…Though studies on the cultured normal rat IMCD do not support inhibition of AVP-stimulated cAMP generation by PGE2 (28), we considered the possibility that excess PG production may be responsible for the lack of AVP-responsiveness in CRF. Therefore, we examined the response of CRF cells to AVP in the background of cyclooxygenase inhibition with 5 uM flurbiprofen which we have previously shown to decrease ionophore-stimulated PGE2 production by > 97% (29). However, as seen in Fig.…”

Cyclic adenosine monophosphate and diacylglycerol. Mutually inhibitory second messengers in cultured rat inner medullary collecting duct cells.

“…Abbreviations used in this paper: AC, adenylyl cyclase; DAG, diacylglycerol; DOG, dioctanoylglycerol; EGF, epidermal growth factor; H7, 1-(5-isoquinolinylsulfonyl).2-methylpiperazine; H8, N-[2-methylamino)ethyl]-5-isoquinoline-sulfonamide; IPI, inositol monophosphate; IP2, inositol bisphosphate; IP3, inositol trisphosphate; PLA2, phospholipase A2; PLC, phospholipase C; RIMCT, rat inner medullary collecting tubule. ble for mediating the enhanced hydraulic conductivity of the apical membrane. Recent studies from this laboratory have demonstrated that in addition to AC activity, cultured inner medullary collecting duct cells also exhibit hormonal stimulation of phospholipase C (PLC) activity upon exposure to epidermal growth factor (EGF) (1).…”