Bradford C Berk

University of Rochester, Rochester, New York, United States

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Publications (315)2227.09 Total impact

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    ABSTRACT: Endochondral ossification, an important stage of fracture healing, is regulated by a variety of signaling pathways. Transforming growth factor β (TGFβ) superfamily plays important roles and comprises TGFβs, bone morphogenetic proteins (BMPs), and growth differentiation factors. TGFβs primarily regulate cartilage formation and endochondral ossification. BMP2 shows diverse efficacy, from the formation of skeleton and extraskeletal organs to the osteogenesis and remodeling of bone. G-protein-coupled receptor kinase 2-interacting protein-1 (GIT1), a shuttle protein in osteoblasts, facilitates fracture healing by promoting bone formation and increasing the secretion of vascular endothelial growth factor. Our study examined whether GIT1 regulates fracture healing through the BMP2 signaling pathway and/or through the TGFβ signaling pathway. GIT1 knockout (KO) mice exhibited delayed fracture healing, chondrocyte accumulation in the fracture area, and reduced staining intensity of phosphorylated Smad1/5/8 (pSmad1/5/8) and Runx2. Endochondral mineralization diminished while the staining intensity of phosphorylated Smad2/3 (pSmad2/3) showed no significant change. Bone marrow mesenchymal stem cells extracted from GIT1 KO mice showed a decline of pSmad1/5/8 levels and of pSmad1/5/8 translocated into the cell nucleus after BMP2 stimulus. We detected no significant change in the pSmad2/3 level after TGFβ1 stimulus. Data obtained from reporter gene analysis of C3H10T1/2 cells cultured in vitro confirmed these findings. GIT1-siRNA inhibited transcription in the cell nucleus via pSmad1/5/8 after BMP2 stimulus but had no significant effect on transcription via pSmad2/3 after TGFβ1 stimulus. Our results indicate that GIT1 regulates Smad1/5/8 phosphorylation and mediates BMP2 regulation of Runx2 expression, thus affecting endochondral ossification at the fracture site.
    Molecular and Cellular Biochemistry 08/2014; · 2.33 Impact Factor
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    ABSTRACT: Carotid intima formation is a significant risk factor for cardiovascular disease. C3H/FeJ (C3H/F) and SJL/J (SJL) inbred mouse strains differ in susceptibility to immune and vascular traits. Using a congenic approach we demonstrated that the Intima modifier 2 (Im2) locus on chromosome 11 regulates leukocyte infiltration. We sought to determine whether inflammation was due to changes in circulating immune cells or activation of vascular wall cells in genetically pure Im2 (C3H/F.SJL.11.1) mice. Complete blood counts showed no differences in circulating monocytes between C3H/F and C3H/F.SJL.11.1 compared to SJL mice. Aortic vascular cell adhesion molecule-1 (VCAM-1) total protein levels were dramatically increased in SJL and C3H/F.SJL.11.1 compared to C3H/F mice. Immunostaining of aortic endothelial cells (EC) showed a significant increase in VCAM-1 expression in SJL and C3H/F.SJL.11.1 compared to C3H/F under steady flow conditions. Immunostaining of EC membranes revealed a significant decrease in EC size in SJL and C3H/F.SJL.11.1 versus C3H/F in regions of disturbed flow. Vascular permeability was significantly higher in C3H/F.SJL.11.1 compared to C3H/F. Our results indicate that Im2 regulation of leukocyte infiltration is mediated by EC inflammation and permeability. RNA sequencing and pathway analyses comparing genes in the Im2 locus to C3H/F provides insight into candidate genes that regulate vascular wall inflammation and permeability highlighting important genetic mechanisms that control vascular intima in response to injury.
    Physiological Genomics 07/2014; · 2.81 Impact Factor
  • Oded N Spindel, Ryan M Burke, Chen Yan, Bradford C Berk
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    ABSTRACT: Fluid shear stress (FSS) differentially regulates endothelial cell (EC) stress fiber formation with decreased stress fibers in areas of disturbed-flow (d-flow) compared to steady-flow (s-flow) areas. Importantly, stress fibers are critical for several EC functions including cell shape, mechano-signal transduction, and EC cell-cell junction integrity. A key mediator of s-flow induced stress fiber formation is Src, which regulates downstream signaling mediators such as phosphorylation of cortactin, activity of focal adhesion kinase and small GTPases. Previously we showed that thioredoxin-interacting protein (TXNIP, also VDUP1 and TBP-2) was regulated by FSS; TXNIP expression was increased in d-flow compared to s-flow areas. While TXNIP was originally characterized for its role in redox and metabolic cellular functions, recent reports show important scaffold functions related to its α-arrestin structure. Based on these findings, we hypothesized that TXNIP acts as a biomechanical sensor that regulates Src kinase activity and stress fiber formation. Using en face immunohistochemistry of the aorta and cultured EC, we show inverse relationship between TXNIP expression and Src activity. Specifically, s-flow increased Src activity and stress fiber formation, while it decreased TXNIP expression. In contrast, d-flow had opposite effects. We studied the role of TXNIP in regulating SHP2 plasma membrane localization and VE-cadherin binding, because SHP2 indirectly regulates dephosphorylation of Src tyrosine 527 that inhibits Src activity. Using immunohistochemistry and immunoprecipitation we found that TXNIP prevented SHP2-VE-cadherin interaction. In summary, these data characterize a FSS mediated mechanism for stress fiber formation that involves a TXNIP-dependent VE-cadherin-SHP2-Src pathway.
    Circulation Research 02/2014; · 11.86 Impact Factor
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    ABSTRACT: Cyclophilin A (CyPA) is an important mediator in cardiovascular diseases. It possesses peptidyl-prolyl cis-trans isomerase activity (PPIase) and chaperone functions, which regulate protein folding, intracellular trafficking and reactive oxygen species (ROS) production. Platelet glycoprotein receptor αIIbβ3 integrin activation is the common pathway for platelet activation. IT was our objective to understand the mechanism by which CyPA-regulates αIIbβ3 activation in platelets. Mice deficient for CyPA (CyPA-/-) had prolonged tail bleeding time compared to wild-type (WT) controls despite equivalent platelet numbers. In vitro studies revealed that CyPA-/- platelets exhibited dramatically decreased thrombin-induced platelet aggregation. In vivo, formation of occlusive thrombi following FeCl3 injury was also significantly impaired in CyPA-/- mice compared with WT-controls. Furthermore, CyPA deficiency inhibited flow-induced thrombus formation in vitro. Flow cytometry demonstrated that thrombin-induced ROS production and αIIbβ3 activation were reduced in CyPA-/- platelets. Coimmunoprecipitation studies showed ROS-dependent increased association of CyPA and αIIbβ3. This association was dependent upon the PPIase activity of CyPA. Significantly, fibrinogen-platelet binding, platelet spreading and cytoskeleton reorganisation were also altered in CyPA-/- platelets. Moreover, CyPA deficiency prevented thrombin-induced αIIbβ3 and cytoskeleton association. In conclusion, CyPA is an important mediator in platelet function by regulation of αIIbβ3 bidirectionalsignalling through increased ROS production and facilitating interaction between αIIbβ3 and the cell cytoskeleton.
    Thrombosis and Haemostasis 01/2014; 111(5). · 5.76 Impact Factor
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    ABSTRACT: G protein coupled receptor kinase 2 (GRK2) interacting protein-1 (GIT1), is a scaffold protein that plays an important role in angiogenesis and osteoclast activity. We have previously demonstrated that GIT1 knockout (GIT1 KO) mice have impaired angiogenesis and dysregulated osteoclast podosome formation leading to a reduction in the bone resorbing ability of these cells. Since both angiogenesis and osteoclast-mediated bone remodeling are involved in the fracture healing process, we hypothesized that GIT1 participates in the normal progression of repair following bone injury. In the present study, comparison of fracture healing in wild type (WT) and GIT1 KO mice revealed altered healing in mice with loss of GIT1 function. Alcian blue staining of fracture callus indicated a persistence of cartilagenous matrix in day 21 callus samples from GIT1 KO mice which was temporally correlated with increased type 2 collagen immunostaining. GIT1 KO mice also showed a decrease in chondrocyte proliferation and apoptosis at days 7 and 14, as determined by PCNA and TUNEL staining. Vascular microcomputed tomography analysis of callus samples at days 7, 14 and 21 revealed decreased blood vessel volume, number, and connection density in GIT1 KO mice compared to WT controls. Correlating with this, VEGF-A, phospho-VEGFR2 and PECAM1 (CD31) were decreased in GIT1 KO mice, indicating reduced angiogenesis with loss of GIT1. Finally, calluses from GIT1 KO mice displayed a reduced number of tartrate resistant acid phosphatase-positive osteoclasts at days 14 and 21. Collectively, these results indicate that GIT1 is an important signaling participant in fracture healing, with gene ablation leading to reduced callus vascularity and reduced osteoclast number in the healing callus.
    PLoS ONE 01/2014; 9(2):e89127. · 3.53 Impact Factor
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    ABSTRACT: Cyclophilin A (CyPA) is a proinflammatory mediator involved in oxidative stress related cardiovascular diseases. It is secreted from VSMC in response to reactive oxygen species (ROS) in a highly regulated manner. Extracellular CyPA activates vascular smooth muscle cells (VSMC) and endothelial cells (EC) promoting inflammation, cell growth, and cell death. Recently, it was shown that acetylated-CyPA (AcK-CyPA) affects its function. We investigated the role of acetylation of CyPA for its secretion and signaling in vascular cells.Methods and ResultsWe used AngII to create sustained ROS and found significantly increased AcK-CyPA in VSMC. Site directed mutagenesis showed that lysines K82 and K125 were the predominant CyPA residues acetylated in response to AngII. Importantly, acetylation of K82 and K125 were required for AngII-mediated CyPA secretion. ROS inhibitors, Tiron and N-acetylcysteine inhibited AngII-induced intracellular CyPA acetylation as well as AcK-CyPA secretion. Using secreted CyPA from wild type and K82/125R mutants expressed in transduced VSMC or in vitro acetylated recombinant CyPA, we showed that extracellular AcK-CyPA significantly increased pERK1/2, matrix metalloproteinase 2 activation, as well as ROS production in VSMC compared to non-acetylated CyPA. Moreover, extracellular AcK-CyPA increased adhesion molecules expression (VCAM-1 and ICAM-1) in EC, which promoted monocyte adhesion. ROS-dependent acetylation of CyPA is required for the generation of extracellular CyPA. Acetylated extracellular CyPA regulates VSMC and EC activation suggesting that inhibition of acetylation of CyPA may prevent the pathogenesis of oxidative stress related cardiovascular diseases.
    Cardiovascular Research 11/2013; · 5.81 Impact Factor
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    ABSTRACT: Recent evidence suggests G-protein-coupled receptor-2-interacting protein-1 (GIT1) overexpression in several human metastatic tumors, including breast, lung, and prostate. Tumor metastasis is associated with an increase in angiogenesis. We have showed previously that GIT1 is required for postnatal angiogenesis during lung development. However, the functional role of GIT1 in pathological angiogenesis during tumor growth is unknown. In the present study, we show inhibition of angiogenesis in matrigel implants as well as reduced tumor angiogenesis and melanoma tumor growth in GIT1-knockout mice. We demonstrate that this is a result of impaired directional migration of GIT1-depleted endothelial cells toward a vascular endothelial growth factor gradient. Cortactin-mediated lamellipodia formation in the leading edge is critical for directional migration. We observed a significant reduction in cortactin localization and lamellipodia formation in the leading edge of GIT1-depleted endothelial cells. We specifically identified that the Spa homology domain (aa 250-420) of GIT1 is required for GIT1-cortactin complex localization to the leading edge. The mechanisms involved extracellular signal-regulated kinases 1 and 2-mediated Cortactin-S405 phosphorylation and activation of Rac1/Cdc42. Finally, using gain of function studies, we show that a constitutively active mutant of cortactin restored directional migration of GIT1-depleted cells. Our data demonstrated that a GIT1-cortactin association through GIT1-Spa homology domain is required for cortactin localization to the leading edge and is essential for endothelial cell directional migration and tumor angiogenesis.
    Arteriosclerosis Thrombosis and Vascular Biology 11/2013; · 6.34 Impact Factor
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    ABSTRACT: Angiotensin II (AngII) signal transduction in vascular smooth muscle cells (VSMC) is mediated by reactive oxygen species (ROS). Cyclophilin A (CyPA) is a ubiquitously expressed cytosolic protein that possesses peptidyl-prolyl cis-trans isomerase activity, scaffold function, and significantly enhances AngII-induced ROS production in VSMC. We hypothesized that CyPA regulates AngII-induced ROS generation by promoting translocation of NADPH oxidase cytosolic subunit p47phox to caveolae of the plasma membrane. Overexpression of CyPA in CyPA-deficient VSMC (CyPA(-/-)VSMC) significantly increased AngII-stimulated ROS production. NADPH oxidase inhibitors (VAS2870 or diphenylene iodonium) significantly attenuated AngII-induced ROS production in CyPA and p47phox-overexpressing CyPA(-/-)VSMC. Cell fractionation and sucrose gradient analyses showed that AngII-induced p47phox plasma membrane translocation, specifically to the caveolae, was reduced in CyPA(-/-)VSMC compared with wild-type-VSMC. Immunofluorescence studies demonstrated that AngII increased p47phox and CyPA colocalization and translocation to the plasma membrane. In addition, immunoprecipitation of CyPA followed by immunoblotting of p47phox and actin showed that AngII increased CyPA and p47phox interaction. AngII-induced p47phox and actin cell cytoskeleton association was attenuated in CyPA(-/-)VSMC. Mechanistically, inhibition of p47phox phosphorylation and phox homology domain deletion attenuated CyPA and p47phox interaction. Finally, cyclosporine A and CyPA-peptidyl-prolyl cis-trans isomerase mutant, R55A, inhibited AngII-stimulated CyPA and p47phox association in VSMC, suggesting that peptidyl-prolyl cis-trans isomerase activity was required for their interaction. These findings provide the mechanism by which CyPA is an important regulator for AngII-induced ROS generation in VSMC through interaction with p47phox and cell cytoskeleton, which enhances the translocation of p47phox to caveolae.
    Arteriosclerosis Thrombosis and Vascular Biology 07/2013; · 6.34 Impact Factor
  • Jun-Ichi Abe, Bradford C Berk
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    ABSTRACT: Athero-prone flow promotes inflammation in endothelial cells, and this process is critical for pathogenesis of many chronic inflammatory conditions such as coronary and carotid artery atherosclerosis, as well as abdominal aortic aneurysm. Signal mediators activated by athero-prone (disturbed) flow that have been described include NF-κB and protein kinase C, which is very different from athero-protective (steady laminar) flow(1). In this issue a publication from Shyy's lab shows the critical role of sterol regulatory element binding protein 2 (SREBP2) on athero-prone flow-mediated NLRP3 inflammasome activation(2). In particular, they showed that athero-prone flow induced both mature form of SREBP2 (SREBP2-N) and SREBP2 mRNA induction, which transcriptionally increase NADPH oxidase 2 (Nox2) and NLRP3 expression, thereby leading to IL-1β expression and endothelial inflammation (Figure 1). In this editorial, we will briefly review the NLRP3 inflammasome and SREBP activation system, which play a key role in modulating athero-prone flow-mediated EC inflammation. We will also discuss the following important questions for the future; the role of local NLRP3 and IL-1β expression, mechanisms for two different types of flow (athero-prone flow vs. athero-protective flow) on SREBP2 activation, and other NLRP3 activators including thioredoxin-interacting protein (TXNIP).
    Circulation 07/2013; · 15.20 Impact Factor
  • Jun-Ichi Abe, Bradford C Berk
    Circulation Research 06/2013; 112(12):1526-8. · 11.86 Impact Factor
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    ABSTRACT: OBJECTIVE: We demonstrated that inflammatory cells and intima-media thickening are increased in carotids exposed to low-blood flow in the SJL/J (SJL) strain compared with other mouse strains. We hypothesized that the extent of inflammation associated with intima-media thickening is a genetically regulated trait.Approach and Results-We performed a whole genome approach to measure leukocyte infiltration in the carotid intima as a quantitative trait in a genetic cross between C3HeB/FeJ (C3H/F) and SJL mice. Immunostaining for CD45+ (a pan-specific leukocyte marker) was performed on carotids from C3H/F, SJL, F1, and N2 progeny to measure leukocyte infiltration. We identified a nearly significant quantitative trait locus for CD45+ on chromosome (chr) 11 (17 cM, LOD=2.3; significance was considered at threshold P=0.05). Interval mapping showed that the CD45+ locus on chr 11 accounted for 8% of the variation in the C3H/FxSJL backcross. Importantly, the CD45+ locus colocalized with the intima-modifier 2 (Im2) locus, which controls 17% of intima variation. We created 2 Im2 congenic lines of mice (C3H/F.SJL.11.1 and C3H/F.SJL.11.2) to better understand the regulation of intima-media thickening by the chr 11 locus. The C3H/F.SJL.11.1 congenic mouse showed ≈30% of the SJL trait, confirming that CD45+ cell infiltration contributed to the intima trait. CONCLUSIONS: We discovered a novel locus on chr 11 that controls leukocyte infiltration in the carotid. Importantly, this locus overlaps with our previously published Im2 locus on chr 11. Our study reveals a potential mechanistic relationship between leukocyte infiltration and intima-media thickening in response to decreased blood flow.
    Arteriosclerosis Thrombosis and Vascular Biology 02/2013; · 6.34 Impact Factor
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    ABSTRACT: OBJECTIVE: The G-protein-coupled receptor kinase interacting protein-1 (GIT1) is a scaffold protein that is important for phospholipase Cγ and extracellular signal-regulated kinase 1/2 signaling induced by angiotensin II and epidermal growth factor. Because GIT1 regulates signaling by several vascular smooth muscle cell (VSMC) growth factors, we hypothesized that intima formation would be inhibited by GIT1 depletion.Approach and Results-Complete carotid ligation was performed on GIT1 wild-type and knockout (KO) mice. We compared changes between GIT1 wild-type and KO mice in carotid vascular remodeling, VSMC proliferation, and apoptosis in vivo and in vitro. Our data demonstrated that GIT1 deficiency significantly decreased intima formation after carotid ligation as a result of both reduced VSMC proliferation and enhanced apoptosis. To confirm the effects of GIT1 in vitro, we performed proliferation and apoptosis assays in VSMC. In mouse aortic smooth muscle cells (MASM), we found that the growth rate and [3H]-thymidine incorporation of the GIT1 KO MASM were significantly decreased compared with the wild-type MASM. Cyclin D1, which is a key cell cycle regulator, was significantly decreased in GIT1 KO cells. Serum deprivation of GIT1 KO MASM increased apoptosis 3-fold compared with wild-type MASM. Treatment of rat aortic smooth muscle cells with GIT1 small interfering RNA impaired cell migration. Both phospholipase Cγ and extracellular signal-regulated kinase 1/2 signaling were required for GIT1-dependent VSMC proliferation and migration, whereas only phospholipase Cγ was involved in GIT1-mediated VSMC apoptosis. CONCLUSIONS: GIT1 is a novel mediator of vascular remodeling by regulating VSMC proliferation, migration, and apoptosis through phospholipase Cγ and extracellular signal-regulated kinase 1/2 signaling pathways.
    Arteriosclerosis Thrombosis and Vascular Biology 02/2013; · 6.34 Impact Factor
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    ABSTRACT: OBJECTIVE: Thioredoxin-interacting protein (TXNIP) is an α-arrestin protein whose function is important for the regulation of vascular endothelial growth factor receptor 2 (VEGFR2) signaling and endothelial cell survival. Because VEGFR2 is critical for angiogenesis, we explored the role of TXNIP in VEGF-induced angiogenesis.Approach and Results-TXNIP knockdown inhibited VEGF-induced endothelial cell tube formation and proliferation in cultured human umbilical vein endothelial cell. To elucidate the mechanism by which TXNIP altered VEGFR2 signaling in human umbilical vein endothelial cell, we studied phosphorylation of VEGFR2, PLCγ1, endothelial NO synthase, and Akt. TXNIP knockdown significantly decreased phosphorylation of VEGFR2 and PLCγ1 at times >5 minutes, but phosphorylation was unchanged at 2 minutes, as was Akt and endothelial NO synthase phosphorylation. Cell-surface biotinylation assay showed that TXNIP knockdown significantly attenuated VEGFR2 internalization. These results suggested that TXNIP was required for sustained VEGFR2 signaling, which is mediated largely by internalized VEGFR2. Rab5 knockdown to inhibit the trafficking and fusion of early endosomes significantly blocked VEGF-induced VEGFR2 internalization and phosphorylation of VEGFR2 and PLCγ1. Immunofluorescence and coimmunoprecipitation showed that TXNIP was part of a complex that included Rab5 and VEGFR2. Finally, TXNIP knockdown prevented the association of VEGFR2 and Rab5. CONCLUSIONS: Our results show that TXNIP is essential for VEGFR2 internalization in Rab5 positive endosomes, which is required for endothelial cell growth and angiogenesis.
    Arteriosclerosis Thrombosis and Vascular Biology 02/2013; · 6.34 Impact Factor
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    ABSTRACT: BACKGROUND: Carotid intima-media thickening is associated with increased cardiovascular risk in humans. We discovered that intima formation and cell proliferation in response to carotid injury is greater in SJL/J (SJL) compared to C3HeB/FeJ (C3H/F) mice. The purpose of this study was to identify candidate genes contributing to intima formation. METHODS AND RESULTS: We performed microarray and bioinformatic analyses of carotid arteries from C3H/F and SJL mice. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the ribosome pathway was significantly up-regulated in C3H/F compared to SJL. Expression of a ribosomal protein, RpL17, was >40-fold higher in C3H/F carotids compared to SJL. Aortic vascular smooth muscle cells (VSMC) from C3H/F grew slower compared to SJL. To determine the role of RpL17 in VSMC growth regulation we analyzed the relationship between RpL17 expression and cell cycle progression. Cultured VSMC from mouse, rat, and human showed that RpL17 expression inversely correlated with growth as shown by decreased cells in S phase and increased cells in G(0)/G(1). To prove that RpL17 acted as a growth inhibitor in vivo we used pluronic gel delivery of RpL17 siRNA to C3H/F carotid arteries. This resulted in an 8-fold increase in the number of proliferating cells. Furthermore, following partial carotid ligation in SJL mice, RpL17 expression in the intima and media decreased while the number of proliferating cells increased. CONCLUSIONS: RpL17 acts as a VSMC growth inhibitor (akin to a tumor suppressor) and represents a potential therapeutic target to limit carotid intima-media thickening.
    Circulation 10/2012; · 15.20 Impact Factor
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    ABSTRACT: OBJECTIVE: Protein kinase C (PKC) ζ is a key pathological mediator of endothelial cell apoptosis. p62 is a scaffold protein that regulates several cell signaling pathways by binding to target proteins. Because PKCζ and p62 contain Phox/Bem1p (PB1) modules that mediate protein-protein interactions, we hypothesized that an interaction between p62 and PKCζ is required for tumor necrosis factor α-induced PKCζ signaling in endothelial cells. METHODS AND RESULTS: In human umbilical vein endothelial cell, tumor necrosis factor α (10 ng/mL) enhanced the interaction between p62 and PKCζ. Transfection with p62 small interfering RNA reduced the activation of both PKCζ and its downstream targets JNK and caspase 3, suggesting that p62 is necessary for PKCζ signaling. Overexpression of only the PB1 domain of p62 inhibited p62-PKCζ interaction, showing that binding of these 2 proteins is mediated by their PB1 domains. Furthermore, overexpression of the p62 PB1 domain suppressed tumor necrosis factor α-induced PKCζ activation and subsequent activation of JNK and caspase 3. Finally, transfection of either p62 small interfering RNA or the PB1 domain of p62 inhibited human umbilical vein endothelial cell apoptosis. CONCLUSIONS: Our results suggest a novel function of p62 that regulates the activity of PKCζ by binding to PKCζ, thereby activating the PKCζ-JNK-caspase 3 apoptotic pathway in endothelial cells.
    Arteriosclerosis Thrombosis and Vascular Biology 09/2012; · 6.34 Impact Factor
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    ABSTRACT: Human apolipoprotein E has three isoforms: APOE2, APOE3 and APOE4. APOE4 is a major genetic risk factor for Alzheimer's disease and is associated with Down's syndrome dementia and poor neurological outcome after traumatic brain injury and haemorrhage. Neurovascular dysfunction is present in normal APOE4 carriers and individuals with APOE4-associated disorders. In mice, lack of Apoe leads to blood-brain barrier (BBB) breakdown, whereas APOE4 increases BBB susceptibility to injury. How APOE genotype affects brain microcirculation remains elusive. Using different APOE transgenic mice, including mice with ablation and/or inhibition of cyclophilin A (CypA), here we show that expression of APOE4 and lack of murine Apoe, but not APOE2 and APOE3, leads to BBB breakdown by activating a proinflammatory CypA-nuclear factor-κB-matrix-metalloproteinase-9 pathway in pericytes. This, in turn, leads to neuronal uptake of multiple blood-derived neurotoxic proteins, and microvascular and cerebral blood flow reductions. We show that the vascular defects in Apoe-deficient and APOE4-expressing mice precede neuronal dysfunction and can initiate neurodegenerative changes. Astrocyte-secreted APOE3, but not APOE4, suppressed the CypA-nuclear factor-κB-matrix-metalloproteinase-9 pathway in pericytes through a lipoprotein receptor. Our data suggest that CypA is a key target for treating APOE4-mediated neurovascular injury and the resulting neuronal dysfunction and degeneration.
    Nature 05/2012; 485(7399):512-6. · 38.60 Impact Factor
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    ABSTRACT: Endothelial cells (EC) at regions exposed to disturbed flow (d-flow) are predisposed to inflammation and the subsequent development of atherosclerosis. We previously showed that thioredoxin interacting protein (TXNIP) was required for tumor necrosis factor-mediated expression of vascular cell adhesion molecule-1. We sought to investigate the role of TXNIP in d-flow-induced cell adhesion molecule expression and leukocyte interaction with vessels, and the mechanisms by which TXNIP suppresses athero-protective gene expression. Using en face staining of mouse aorta, we found a dramatic increase of TXNIP in EC at sites exposed to d-flow as compared to steady flow. EC-specific TXNIP (EC-TXNIP) knockout mice showed significant decreases in vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 mRNA expression in the d-flow regions of mouse aorta. Intravital microscopy of mesenteric venules showed that leukocyte rolling time was decreased, whereas rolling velocity was increased significantly in EC-TXNIP knockout mice. In vitro experiments using a cutout flow chamber to generate varying flow patterns showed that increased TXNIP was required for d-flow-induced EC-monocyte adhesion. Furthermore, we found that the expression of Kruppel-like factor 2, a key anti-inflammatory transcription factor in EC, was inhibited by TXNIP. Luciferase and chromatin immunoprecipitation assays showed that TXNIP was present within a repressing complex on the Kruppel-like factor 2 promoter. These data demonstrate the essential role for TXNIP in mediating EC-leukocyte adhesion under d-flow, as well as define a novel mechanism by which TXNIP acts as a transcriptional corepressor to regulate Kruppel-like factor 2-dependent gene expression.
    Circulation Research 02/2012; 110(4):560-8. · 11.86 Impact Factor
  • Oded N Spindel, Chen Yan, Bradford C Berk
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    ABSTRACT: Thioredoxin-interacting protein (TXNIP) and poly-ADP-ribose polymerase 1 (PARP1) are both regulated by changes in cellular reduction-oxidation (redox) state and localize to the nucleus basally in human umbilical vein endothelial cells (HUVEC). Previously we showed a novel mechanism for PARP1 inhibition-mediated HUVEC survival through activation of vascular endothelial growth factor receptor 2 (VEGFR2) signaling in response to stress-induced apoptosis. In addition, we showed TXNIP translocation to the plasma membrane (PM) and activation of VEGFR2 in response to physiological stimuli. Because TXNIP is an α-arrestin that regulates VEGFR2 signaling, we hypothesized that PARP1 regulates TXNIP localization and function that might affect HUVEC stress-induced apoptosis. HUVEC treated with 10 μmol/L PARP1 inhibitor (PJ34) were protected from TNF (10 ng/mL) or H(2)O(2) (300 μmol/L) mediated cell death. HUVEC transfected with TXNIP siRNA lost the protective effect of PARP1 inhibition, suggesting a protective role for TXNIP. Using immunofluorescence, cell fractionation analysis, and plasma membrane sheet assay, TXNIP was shown to translocate to the plasma membrane after PARP1 inhibition. TXNIP translocation was associated with activation of VEGFR2 signaling. Functionally, TXNIP-PARP1 interaction was decreased on PJ34 treatment, suggesting PARP1 as a novel regulator of TXNIP localization and function. These findings demonstrate a novel regulatory mechanism of TXNIP by PARP1 to mediate activation of plasma membrane signaling and cell survival.
    Arteriosclerosis Thrombosis and Vascular Biology 02/2012; 32(5):1264-70. · 6.34 Impact Factor
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    Journal of Molecular and Cellular Cardiology 01/2012; 52(1):292. · 5.15 Impact Factor
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    Oded N Spindel, Bradford C Berk
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    ABSTRACT: Cardiac ischemia-reperfusion (I-R) injury occurs upon prompt restoration of blood flow to the ischemic myocardium after an acute myocardial infarction. Interestingly, many of the features of I-R injury are related to impaired mitochondrial signaling and mitochondrial dysfunction. Restoring cardiac energy bioavailability and reduction-oxidation (redox) signaling are therefore important in recovery after I-R injury. In this issue of the JCI, Yoshioka and colleagues describe an important and unexpected role for thioredoxin-interacting protein (TXNIP) in the control of mitochondrial respiration and cell energy metabolism. Their findings could open the door for development of TXNIP-targeted therapeutic approaches for the treatment of cardiac I-R injury.
    The Journal of clinical investigation 12/2011; 122(1):30-2. · 15.39 Impact Factor

Publication Stats

14k Citations
2,227.09 Total Impact Points

Institutions

  • 1998–2014
    • University of Rochester
      • • Aab Cardiovascular Research Institute
      • • Division of Hospital Medicine
      • • Aab Institute of Biomedical Sciences
      • • Department of Medicine
      Rochester, New York, United States
  • 1999–2010
    • University Center Rochester
      • Center for Cardiovascular Research
      Rochester, Minnesota, United States
  • 2009
    • Texas A&M University
      • Department of Health and Kinesiology
      College Station, TX, United States
  • 2008
    • Cornell University
      • Department of Biomedical Engineering
      Ithaca, NY, United States
  • 2005
    • Yonsei University
      Sŏul, Seoul, South Korea
  • 2004
    • King's College London
      • Institute of Psychiatry
      London, ENG, United Kingdom
  • 1995–1999
    • University of Washington Seattle
      • • Division of Cardiology
      • • Department of Medicine
      Seattle, WA, United States
  • 1992–1997
    • Georgia Institute of Technology
      • • Institute for Bioengineering and Bioscience
      • • School of Mechanical Engineering
      Atlanta, Georgia, United States
    • Icahn School of Medicine at Mount Sinai
      Manhattan, New York, United States
  • 1989–1997
    • Emory University
      • • Biochemistry
      • • Division of Cardiology
      • • School of Medicine
      • • Department of Internal Medicine
      Atlanta, Georgia, United States
    • Boston Children's Hospital
      Boston, Massachusetts, United States
  • 1996
    • Loyola University Medical Center
      • Department of Physiology
      Maywood, IL, United States
  • 1993
    • University of California, San Diego
      • Department of Pediatrics
      San Diego, CA, United States
  • 1991
    • Taipei Veterans General Hospital
      • Cardiology Division
      Taipei, Taipei, Taiwan
  • 1988–1989
    • Harvard Medical School
      • Department of Medicine
      Boston, Massachusetts, United States
  • 1987–1989
    • Brigham and Women's Hospital
      • • Department of Medicine
      • • Division of Cardiovascular Medicine
      Boston, MA, United States