PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-7 (7)
 

Clipboard (0)
None
Journals
Authors
more »
Year of Publication
Document Types
1.  δPKC mediates microcerebrovascular dysfunction in acute ischemia and in chronic hypertensive stress in vivo 
Brain research  2007;1144:146-155.
Maintaining cerebrovascular function is a priority for reducing damage following acute ischemic events such as stroke, and under chronic stress in diseases such as hypertension. Ischemic episodes lead to endothelial cell damage, deleterious inflammatory responses, and altered neuronal and astrocyte regulation of vascular function. These, in turn, can lead to impaired cerebral blood flow and compromised blood–brain barrier function, promoting microvascular collapse, edema, hemorrhagic transformation, and worsened neurological recovery. Multiple studies demonstrate that protein kinase C (PKC), a widely expressed serine/threonine kinase, is involved in mediating arterial tone and microvascular function. However, there is no clear understanding about the role of individual PKC isozymes. We show that intraperitoneal injection of δV1-1–TAT47–57 (0.2 mg/kg in 1 mL), an isozymespecific peptide inhibitor of δPKC, improved microvascular pathology, increased the number of patent microvessels by 92% compared to control-treated animals, and increased cerebral blood flow by 26% following acute focal ischemia induced by middle cerebral artery occlusion in normotensive rats. In addition, acute delivery of δV1-1–TAT47–57 in hypertensive Dahl rats increased cerebral blood flow by 12%, and sustained delivery δV1-1–TAT47–57 (5 uL/h, 1 mM), reduced infarct size by 25% following an acute stroke induced by MCA occlusion for 90 min. Together, these findings demonstrate that δPKC is an important therapeutic target for protection of microvascular structure and function under both acute and chronic conditions of cerebrovascular stress.
doi:10.1016/j.brainres.2007.01.113
PMCID: PMC3742377  PMID: 17350602
Cerebral blood flow; Hypertension; Microvasculature; Protein kinase C; Stroke; Vasculature
2.  Insight into intra- and inter-molecular interactions of PKC: design of specific modulators of kinase function 
Protein kinase C (PKC) is a family of kinases that are critical in many cellular events. These enzymes are activated by lipid-derived second messengers, are dependent on binding to negatively charged phospholipids and some members also require calcium to attain full activation. The interaction with lipids and calcium activators is mediated by binding to the regulatory domains C1 and C2. In addition, many protein-protein interactions between PKC and other proteins have been described. These include interactions with adaptor proteins, substrates and cytoskeletal elements. Regulation of the interactions between PKC, small molecules and other proteins is essential for signal transduction to occur. Finally, a number of auto-inhibitory intramolecular protein-protein interactions have also been identified in PKC. This chapter focuses on mapping the sites for many of these inter and intramolecular interactions and how this information may be used to generate selective inhibitors and activators of PKC signaling.
doi:10.1016/j.phrs.2007.04.014
PMCID: PMC2834269  PMID: 17580120
3.  δPKC Participates in the Endoplasmic Reticulum Stress-Induced Response in Cultured Cardiac Myocytes and Ischemic Heart 
The cellular response to excessive endoplasmic reticulum (ER) stress includes the activation of signaling pathways, which lead to apoptotic cell death. Here we show that treatment of cultured cardiac myocytes with tunicamycin, an agent that induces ER stress, causes the rapid translocation of δPKC to the ER. We further demonstrate that inhibition of δPKC using the δPKC-specific antagonist peptide, δV1-1, reduces tunicamycin-induced apoptotic cell death, and inhibits expression of specific ER stress response markers such as CHOP, GRP78 and phosphorylation of JNK. The physiological importance of δPKC in this event is further supported by our findings that the ER stress response is also induced in hearts subjected to ischemia and reperfusion injury and that this response also involves δPKC translocation to the ER. We found that the levels of the ER chaperone, GRP78, the spliced XBP-1 and the phosphorylation of JNK are all increased following ischemia and reperfusion and that δPKC inhibition by δV1-1 blocks these events. Therefore, ischemia-reperfusion injury induces ER stress in the myocardium in a mechanism that requires δPKC activity. Taken together, our data show for the first time that δPKC activation plays a critical role in the ER stress-mediated response and the resultant cell death.
doi:10.1016/j.yjmcc.2007.07.061
PMCID: PMC2185772  PMID: 17825316
5.  Rational Design of A Selective Antagonist of ε Protein Kinase C Derived From the Selective Allosteric Agonist, Pseudo-Rack Peptide 
We have previously shown that domains involved in binding of protein kinase C (PKC1) isozymes to their respective anchoring proteins (RACKs2) and short peptides derived from these domains are PKC isozyme-selective antagonists. We also identified PKC isozyme-selective agonists, named ψRACK3 peptides, derived from a sequence within each PKC with high homology to its respective RACK. We noted that all the ψRACK sequences within each PKC isozyme have at least one non-homologous amino acid difference from their corresponding RACK that constitutes a charge change. Based on this information, we have devised here a new approach to design an isozyme-selective PKC antagonist, derived from the ψRACK sequence. We focused on εPKC ψRACK peptide, where the pseudo-εRACK sequence (ψεRACK; HDAPIGYD; corresponding to εPKC85-92) is different in charge from the homologous RACK-derived sequence (NNVALGYD; corresponding to εRACK285-292) in the second amino acid. Here we show that changing the charge of the ψεRACK peptide through a substitution of only one amino acid (aspartate to asparagine) resulted in a peptide with an opposite activity on the same cell function and a substitution for aspartate with an alanine resulted in an inactive peptide. These data support our hypothesis regarding the mechanism by which pseudo-RACK peptide activates PKC in heart cells and suggest that this approach is applicable to other signaling proteins with inducible protein-protein interactions.
doi:10.1016/j.yjmcc.2007.01.007
PMCID: PMC1978508  PMID: 17337000
PKC (protein kinase C); RACK (receptor for activated C-kinase); ψRACK (pseudo RACK); intramolecular interaction; carrier peptide
6.  Sustained pharmacological inhibition of δPKC protects against hypertensive encephalopathy through prevention of blood-brain barrier breakdown in rats 
Hypertensive encephalopathy is a potentially fatal condition associated with cerebral edema and the breakdown of the blood-brain barrier (BBB). The molecular pathways leading to this condition, however, are unknown. We determined the role of δPKC, which is thought to regulate microvascular permeability, in the development of hypertensive encephalopathy using δV1-1 — a selective peptide inhibitor of δPKC. As a model of hypertensive encephalopathy, Dahl salt-sensitive rats were fed an 8% high-salt diet from 6 weeks of age and then were infused s.c. with saline, control TAT peptide, or δV1-1 using osmotic minipumps. The mortality rate and the behavioral symptoms of hypertensive encephalopathy decreased significantly in the δV1-1–treated group relative to the control-treated group, and BBB permeability was reduced by more than 60%. Treatment with δV1-1 was also associated with decreased δPKC accumulation in capillary endothelial cells and in the endfeet of capillary astrocytes, which suggests decreased microvasculature disruption. Treatment with δV1-1 prevented hypertension-induced tight junction disruption associated with BBB breakdown, which suggests that δPKC may specifically act to dysregulate tight junction components. Together, these results suggest that δPKC plays a role in the development of hypertension-induced encephalopathy and may be a therapeutic target for the prevention of BBB disruption.
doi:10.1172/JCI32636
PMCID: PMC2147668  PMID: 18097471
7.  Use of a Novel Method to Find Substrates of Protein Kinase C Delta Identifies M2 Pyruvate Kinase 
Protein kinase C (PKC) family members have been implicated in numerous cellular processes. However, identifying the substrates of each PKC isozyme remains a challenge. Here, we describe a method using two dimensional (2-D) isoelectric focusing gel electrophoresis to identify substrates of delta PKC (δPKC) in MCF-7 breast carcinoma cells. We show that M2 pyruvate kinase is a substrate of δPKC, and further characterize the interaction between M2 pyruvate kinase and δPKC in MCF-7 cells by immunoprecipitation. δPKC activation in vitro or in cells did not appear to alter the enzyme activity or polymerization of M2 pyruvate kinase.
doi:10.1016/j.biocel.2007.01.018
PMCID: PMC1931518  PMID: 17337233
Protein Kinase C; Signal transduction; M2-type pyruvate kinase; Heat shock protein 27

Results 1-7 (7)