Involvement of Prostaglandin E2 in Clearance of Aggregated Protein via Protein Kinase A in Glomeruli

Abstract

ABSTRACT-Recently we immunohistochemically demonstrated that prostaglandin E2 (PGE2) promoted the clearance of aggregated bovine serum albumin (a-BSA) deposited in glomeruli. Herein, we investigated the role of PGE2 and its signal transduction in the disposal of macromolecules in glomeruli. EP2 and EP4 receptor mRNA was detected in glomeruli by RT-PCR analysis. A-BSA was injected twice into mice. Glomeruli were then isolated and incubated. A-BSA gradually disappeared from isolated glomeruli. PGE 2 increased the intracellular cyclic AMP and decreased a-BSA level in glomeruli. Additionally, 8-bromocyclic AMP evoked a loss of a-BSA in isolated glomeruli. The effect of 8-bromo-cyclic AMP on the clearance of a-BSA was abolished by KT 5720 in glomeruli. PGE2 and 8-bromo-cyclic AMP also prompted disposal of a-BSA in cultured mesangial cells. These findings indicate that PGE2 positively regulates the removal of macromolecules via cyclic AMP and protein kinase A in glomeruli, and they provide insight into how to prevent the development of glomerulonephritis and glomerulosclerosis.

Involvement of Protein Kinase C in Reduction of Aggregated Protein and Phosphorylation of CREB in Glomeruli

“…Prostaglandin e 2 stimulates production of cyclic amP via eP2 and eP4 prostaglandin e receptors in isolated glomeruli [6,7,14]. we have demonstrated that isolated glomeruli generate prostaglandin e 2 and that a-Bsa increases the expression of cyclooxygenase-2 mrNa and cyclooxygenase-2 activity followed by the expression of prostaglandin e 2 [5].…”

“…we expected the inhibitor of PKa, not PKC, to suppress the phosphorylation, having demonstrated that a-Bsa activated the cyclic amP-PKa system in isolated glomeruli using pharmacological manipulations [6]. other investigators have clarified the ability of isolated glomeruli and mesangial cells to accumulate camP in response to various agonists [10,11].…”

“…samples (3 μl) were subjected to electrophoresis in 10% acrylamide gels, and the proteins were transferred to nitrocellulose membranes. The membranes were subjected to immunoblotting as reported previously [6]. Total (phosphorylated and nonphosphorylated) CreB was detected with the anti-CreB antibody (1:1,000).…”

“…we previously demonstrated that prostaglandin e 2 and 8-bromo cyclic amP accelerate the clearance of aggregated protein from glomeruli, acting through protein kinase a [6]. The prostaglandin e 2 receptor (eP) has a 7-transmembrane structure, and eP2 and eP4 are coupled to the gs protein [8,13].…”

“…The prostaglandin e 2 receptor (eP) has a 7-transmembrane structure, and eP2 and eP4 are coupled to the gs protein [8,13]. The glomeruli express mrNa of eP2 and eP4 [6], produce prostaglandin e 2 , and generate cyclic amP in response to prostaglandin e 2 [12] . wo et al reported that protein kinase C (PKC) mediated increases in the phosphorylation of cyclic amP response element binding protein (CreB) in the spinal cord of rats following an injection of capsaicin [15].…”