peptide-i and Ischemia

We have previously reported that the expression of the receptor for activated C kinase (RACK1) is induced post-ischemia/preperfusion injury to the kidney, and activation of protein kinase C (PKC) protects renal cells from hypoxic injury. This study was done to determine whether the induced expression of RACK1 is accompanied by changes in the level of expression and subcellular distribution of PKC isozymes.. Ischemia/reperfusion injury resulting in acute renal failure was induced by 60 minutes of bilateral renal artery clamping in rats. The expression levels and translocation of various PKC isozymes between soluble and particulate fractions in whole kidney homogenates were demonstrated by immunoblot analysis. The expression pattern of the various PKC isozymes in the kidney postinjury was performed by immunohistochemistry.. PKC alpha, beta II, and zeta were induced and translocated from the soluble fraction to the particulate fraction post-injury. Immunolocalization showed PKC alpha, beta II, and zeta expression to be induced in the proximal tubule epithelial cell (PTEC) at 0 to 30 minutes post-ischemia/reperfusion injury (IRI). At one-day postinjury, the alpha isozyme was translocated to the plasma membrane of the undamaged PTEC, while it was translocated to the nucleus in damaged PTEC. PKC beta II expression was along the basal and lateral side of the undamaged PTEC, while it was distributed in the cytoplasm of sloughed cells in the damaged PTEC. PKC zeta expression at one day was along the apical side of the damaged PTEC. At seven-days postinjury, the expressions of the alpha and zeta isozymes were localized to the plasma membrane of the regenerating PTEC and the expression of PKC beta II isozyme to certain interstitial cells.. The induced expression, translocation, and the intracellular spatial distributions of the enzymes suggest that they may mediate multiple processes during IRI.

Topics: Acute Kidney Injury; Animals; Enzyme Induction; Ischemia; Isoenzymes; Kidney; Kidney Tubules, Proximal; Kinetics; Male; Peptides; Protein Kinase C; Rats; Rats, Sprague-Dawley; Receptors for Activated C Kinase; Reperfusion Injury; Subcellular Fractions

Differential display-polymerase chain reaction (DD-PCR) was used to identify genes that are expressed in kidney following induction of acute ischemic renal injury. The receptor for activated C kinase (RACK1) mRNA expression in kidneys obtained from rats 12 h following ischemia is enhanced twofold compared with sham-operated rats. The maximal enhancement of expression (3.3-fold) is at 7 days following reperfusion. Expression remains elevated at 14 days. RACK1 transcripts and protein are localized to the damaged and regenerating segments of proximal tubules. At 1 day following injury, RACK1 protein is present in the epithelial cells of the damaged S3 segment and in cells sloughed into the tubular lumen. By 5 days following injury, RACK1 protein expression is enhanced in the regenerating cells relining the injured tubules of the S3 segment and in papillary proliferations within regenerating tubules. Increased expression of RACK1 could enhance the activity of PKC and, in so doing, regulate the process of regeneration of the proximal tubule following ischemic renal injury.

Topics: Animals; Ischemia; Kidney; Male; Peptides; Polymerase Chain Reaction; Rats; Rats, Sprague-Dawley; Receptors for Activated C Kinase; Renal Circulation; RNA, Messenger; Time Factors; Tissue Distribution