PKC isoforms in rat medullary thick ascending limb: Selective activation of the δ-isoform by PGE2

Patricia C. Aristimuño, David Good

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

In the medullary thick ascending limb (MTAL) of the rat kidney, prostaglandin E2 (PGE2) reverses inhibition of HCO3/-absorption by arginine vasopressin (AVP). This effect of PGE2 is blocked by chelerythrine or staurosporine and mimicked by pherbol ester, suggesting a critical role for protein kinase C (PKC). The present study was designed to examine directly regulation of PKC isoforms by PGE2 in the inner stripe of the outer medulla and in microdissected MTALs. Immunoblots with isoform-specific anti- PKC antibodies detected α-, βII-, δ-, ε-, and ζ-isoforms in both inner stripe and MTAL. The βI- and γ-isoforms were not detected. Translocation and activation of PKC were assessed by immunoblot analysis and by direct measurement of enzyme activity using an immune complex kinase assay. In inner stripe tissue incubated with 10-10 M AVP, PGE2 (10-6 M for 20 min) induced translocation of PKC-δ from the cytosolic fraction to the membrane fraction. This translocation was associated with an 85% increase in PKC-δ activity in the membrane fraction and a 70% decrease in PKC-δ activity in the cytosolic fraction. PGE2 had no effect on the subcellular distribution or the activities of the other isoforms. Activation of PKC-δ was confirmed directly in microdissected MTALs, in which PGE2 caused a near complete loss of PKC-δ from the cytosolic fraction. PGE2 did not induce translocation of PKC-δ in the absence of AVP. These results demonstrate that 1) the MTAL expresses Ca2+ dependent (α, βII) and Ca2+-independent (δ, ε, ζ) PKC isoforms; 2) PGE2 causes selective activation of PKC-δ, which likely mediates the action of PGE2 to reverse AVP inhibition of HCO3/- absorption; and 3) PGE2 activation of PKC-δ requires the presence of AVP, which may explain the fact that PGE2 influences HCO3/- transport only when AVP is present.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Renal Physiology
Volume272
Issue number5 41-5
StatePublished - May 1997

Fingerprint

Dinoprostone
Protein Kinase C
Protein Isoforms
Extremities
Arginine Vasopressin
Staurosporine
Membranes
Antigen-Antibody Complex
Esters
Phosphotransferases
Kidney

Keywords

  • Adenosine 3',5'-cyclic monophosphate
  • Arginine vasopressin
  • Immunoblotting
  • Prostaglandin E
  • Protein kinase C
  • Renal biocarbonate transport
  • Signal transduction

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

PKC isoforms in rat medullary thick ascending limb : Selective activation of the δ-isoform by PGE2. / Aristimuño, Patricia C.; Good, David.

In: American Journal of Physiology - Renal Physiology, Vol. 272, No. 5 41-5, 05.1997.

Research output: Contribution to journalArticle

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title = "PKC isoforms in rat medullary thick ascending limb: Selective activation of the δ-isoform by PGE2",
abstract = "In the medullary thick ascending limb (MTAL) of the rat kidney, prostaglandin E2 (PGE2) reverses inhibition of HCO3/-absorption by arginine vasopressin (AVP). This effect of PGE2 is blocked by chelerythrine or staurosporine and mimicked by pherbol ester, suggesting a critical role for protein kinase C (PKC). The present study was designed to examine directly regulation of PKC isoforms by PGE2 in the inner stripe of the outer medulla and in microdissected MTALs. Immunoblots with isoform-specific anti- PKC antibodies detected α-, βII-, δ-, ε-, and ζ-isoforms in both inner stripe and MTAL. The βI- and γ-isoforms were not detected. Translocation and activation of PKC were assessed by immunoblot analysis and by direct measurement of enzyme activity using an immune complex kinase assay. In inner stripe tissue incubated with 10-10 M AVP, PGE2 (10-6 M for 20 min) induced translocation of PKC-δ from the cytosolic fraction to the membrane fraction. This translocation was associated with an 85{\%} increase in PKC-δ activity in the membrane fraction and a 70{\%} decrease in PKC-δ activity in the cytosolic fraction. PGE2 had no effect on the subcellular distribution or the activities of the other isoforms. Activation of PKC-δ was confirmed directly in microdissected MTALs, in which PGE2 caused a near complete loss of PKC-δ from the cytosolic fraction. PGE2 did not induce translocation of PKC-δ in the absence of AVP. These results demonstrate that 1) the MTAL expresses Ca2+ dependent (α, βII) and Ca2+-independent (δ, ε, ζ) PKC isoforms; 2) PGE2 causes selective activation of PKC-δ, which likely mediates the action of PGE2 to reverse AVP inhibition of HCO3/- absorption; and 3) PGE2 activation of PKC-δ requires the presence of AVP, which may explain the fact that PGE2 influences HCO3/- transport only when AVP is present.",
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AU - Good, David

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N2 - In the medullary thick ascending limb (MTAL) of the rat kidney, prostaglandin E2 (PGE2) reverses inhibition of HCO3/-absorption by arginine vasopressin (AVP). This effect of PGE2 is blocked by chelerythrine or staurosporine and mimicked by pherbol ester, suggesting a critical role for protein kinase C (PKC). The present study was designed to examine directly regulation of PKC isoforms by PGE2 in the inner stripe of the outer medulla and in microdissected MTALs. Immunoblots with isoform-specific anti- PKC antibodies detected α-, βII-, δ-, ε-, and ζ-isoforms in both inner stripe and MTAL. The βI- and γ-isoforms were not detected. Translocation and activation of PKC were assessed by immunoblot analysis and by direct measurement of enzyme activity using an immune complex kinase assay. In inner stripe tissue incubated with 10-10 M AVP, PGE2 (10-6 M for 20 min) induced translocation of PKC-δ from the cytosolic fraction to the membrane fraction. This translocation was associated with an 85% increase in PKC-δ activity in the membrane fraction and a 70% decrease in PKC-δ activity in the cytosolic fraction. PGE2 had no effect on the subcellular distribution or the activities of the other isoforms. Activation of PKC-δ was confirmed directly in microdissected MTALs, in which PGE2 caused a near complete loss of PKC-δ from the cytosolic fraction. PGE2 did not induce translocation of PKC-δ in the absence of AVP. These results demonstrate that 1) the MTAL expresses Ca2+ dependent (α, βII) and Ca2+-independent (δ, ε, ζ) PKC isoforms; 2) PGE2 causes selective activation of PKC-δ, which likely mediates the action of PGE2 to reverse AVP inhibition of HCO3/- absorption; and 3) PGE2 activation of PKC-δ requires the presence of AVP, which may explain the fact that PGE2 influences HCO3/- transport only when AVP is present.

AB - In the medullary thick ascending limb (MTAL) of the rat kidney, prostaglandin E2 (PGE2) reverses inhibition of HCO3/-absorption by arginine vasopressin (AVP). This effect of PGE2 is blocked by chelerythrine or staurosporine and mimicked by pherbol ester, suggesting a critical role for protein kinase C (PKC). The present study was designed to examine directly regulation of PKC isoforms by PGE2 in the inner stripe of the outer medulla and in microdissected MTALs. Immunoblots with isoform-specific anti- PKC antibodies detected α-, βII-, δ-, ε-, and ζ-isoforms in both inner stripe and MTAL. The βI- and γ-isoforms were not detected. Translocation and activation of PKC were assessed by immunoblot analysis and by direct measurement of enzyme activity using an immune complex kinase assay. In inner stripe tissue incubated with 10-10 M AVP, PGE2 (10-6 M for 20 min) induced translocation of PKC-δ from the cytosolic fraction to the membrane fraction. This translocation was associated with an 85% increase in PKC-δ activity in the membrane fraction and a 70% decrease in PKC-δ activity in the cytosolic fraction. PGE2 had no effect on the subcellular distribution or the activities of the other isoforms. Activation of PKC-δ was confirmed directly in microdissected MTALs, in which PGE2 caused a near complete loss of PKC-δ from the cytosolic fraction. PGE2 did not induce translocation of PKC-δ in the absence of AVP. These results demonstrate that 1) the MTAL expresses Ca2+ dependent (α, βII) and Ca2+-independent (δ, ε, ζ) PKC isoforms; 2) PGE2 causes selective activation of PKC-δ, which likely mediates the action of PGE2 to reverse AVP inhibition of HCO3/- absorption; and 3) PGE2 activation of PKC-δ requires the presence of AVP, which may explain the fact that PGE2 influences HCO3/- transport only when AVP is present.

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KW - Prostaglandin E

KW - Protein kinase C

KW - Renal biocarbonate transport

KW - Signal transduction

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