9 results on '"Parwiz Abrahimi"'
Search Results
2. Effect of Ca(v)beta subunits on structural organization of Ca(v)1.2 calcium channels.
- Author
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Evgeny Kobrinsky, Parwiz Abrahimi, Son Q Duong, Sam Thomas, Jo Beth Harry, Chirag Patel, Qi Zong Lao, and Nikolai M Soldatov
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Medicine ,Science - Abstract
BackgroundVoltage-gated Ca(v)1.2 calcium channels play a crucial role in Ca(2+) signaling. The pore-forming alpha(1C) subunit is regulated by accessory Ca(v)beta subunits, cytoplasmic proteins of various size encoded by four different genes (Ca(v)beta(1)-beta(4)) and expressed in a tissue-specific manner.Methods and resultsHere we investigated the effect of three major Ca(v)beta types, beta(1b), beta(2d) and beta(3), on the structure of Ca(v)1.2 in the plasma membrane of live cells. Total internal reflection fluorescence microscopy showed that the tendency of Ca(v)1.2 to form clusters depends on the type of the Ca(v)beta subunit present. The highest density of Ca(v)1.2 clusters in the plasma membrane and the smallest cluster size were observed with neuronal/cardiac beta(1b) present. Ca(v)1.2 channels containing beta(3), the predominant Ca(v)beta subunit of vascular smooth muscle cells, were organized in a significantly smaller number of larger clusters. The inter- and intramolecular distances between alpha(1C) and Ca(v)beta in the plasma membrane of live cells were measured by three-color FRET microscopy. The results confirm that the proximity of Ca(v)1.2 channels in the plasma membrane depends on the Ca(v)beta type. The presence of different Ca(v)beta subunits does not result in significant differences in the intramolecular distance between the termini of alpha(1C), but significantly affects the distance between the termini of neighbor alpha(1C) subunits, which varies from 67 A with beta(1b) to 79 A with beta(3).ConclusionsThus, our results show that the structural organization of Ca(v)1.2 channels in the plasma membrane depends on the type of Ca(v)beta subunits present.
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- 2009
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3. Ex vivo pretreatment of human vessels with siRNA nanoparticles provides protein silencing in endothelial cells
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Lingfeng Qin, George Tellides, Jiajia Cui, Hong Li, W. Mark Saltzman, Gregory T. Tietjen, Jordan S. Pober, Guangxin Li, Parwiz Abrahimi, and Junwei Zhang
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Graft Rejection ,0301 basic medicine ,Small interfering RNA ,Science ,Genes, MHC Class II ,Transplantation, Heterologous ,General Physics and Astronomy ,Mice, SCID ,Biology ,Major histocompatibility complex ,Article ,General Biochemistry, Genetics and Molecular Biology ,03 medical and health sciences ,Human Umbilical Vein Endothelial Cells ,Gene Knockdown Techniques ,Animals ,Humans ,RNA, Small Interfering ,MHC class II ,Multidisciplinary ,Endothelial Cells ,Organ Transplantation ,General Chemistry ,Transfection ,Molecular biology ,3. Good health ,Cell biology ,Perfusion ,Endothelial stem cell ,Transplantation ,030104 developmental biology ,biology.protein ,Nanoparticles ,Immunologic Memory ,Ex vivo - Abstract
Human endothelial cells are initiators and targets of the rejection response. Pre-operative modification of endothelial cells by small interfering RNA transfection could shape the nature of the host response post-transplantation. Ablation of endothelial cell class II major histocompatibility complex molecules by small interfering RNA targeting of class II transactivator can reduce the capacity of human endothelial cells to recruit and activate alloreactive T cells. Here, we report the development of small interfering RNA-releasing poly(amine-co-ester) nanoparticles, distinguished by their high content of a hydrophobic lactone. We show that a single transfection of small interfering RNA targeting class II transactivator attenuates major histocompatibility complex class II expression on endothelial cells for at least 4 to 6 weeks after transplantation into immunodeficient mouse hosts. Furthermore, silencing of major histocompatibility complex class II reduces allogeneic T-cell responses in vitro and in vivo. These data suggest that poly(amine-co-ester) nanoparticles, potentially administered during ex vivo normothermic machine perfusion of human organs, could be used to modify endothelial cells with a sustained effect after transplantation., The use of gene silencing techniques in the treatment of post-transplantation host rejection is not long lasting and can have systemic effects. Here, the authors utilize a nanocarrier for siRNA for treatment of arteries ex vivo prior to implantation subsequently attenuating immune reaction in vivo.
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- 2017
4. Three Tapasin Docking Sites in TAP Cooperate To Facilitate Transporter Stabilization and Heterodimerization
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Parwiz Abrahimi, Peter Cresswell, Susan M. Mitchell, and Ralf M. Leonhardt
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Immunology ,Protein Disulfide-Isomerases ,Protein Structure, Secondary ,Article ,Protein structure ,Tapasin ,ATP Binding Cassette Transporter, Subfamily B, Member 3 ,Cell Line, Tumor ,MHC class I ,Humans ,Immunology and Allergy ,ATP Binding Cassette Transporter, Subfamily B, Member 2 ,Binding site ,Binding Sites ,biology ,Protein Stability ,Histocompatibility Antigens Class I ,Membrane Transport Proteins ,Transporter associated with antigen processing ,Cell biology ,Biochemistry ,Peptide transport ,biology.protein ,ATP-Binding Cassette Transporters ,Protein Multimerization ,Tapasin binding ,Calreticulin - Abstract
The transporter associated with antigen processing (TAP) translocates peptide antigens into the lumen of the endoplasmic reticulum (ER) for loading onto major histocompatibility complex (MHC) class I molecules. MHC class I acquires its peptide cargo in the peptide loading complex (PLC), an oligomeric complex that the chaperone tapasin organizes by bridging TAP to MHC class I and recruiting accessory molecules such as ERp57 and calreticulin. Three tapasin binding sites on TAP have been described, two of which are located in the N-terminal domains (N domains) of TAP1 and TAP2. The third binding site is present in the core transmembrane domain (coreTMD) of TAP1 and is only used by the unassembled subunits. Tapasin is required to promote TAP stability, but through which binding site(s) it is acting is unknown. In particular the role of tapasin binding to the coreTMD of TAP1 single chains is mysterious as this interaction is lost upon TAP2 association. In this study, we map the respective binding site in TAP1 to the polar face of the amphipathic transmembrane helix TM9 and identify key residues that are essential to establish the interaction. We find that this interaction is dispensable for the peptide transport function but essential to achieve full stability of human TAP1. The interaction is also required for proper heterodimerization of the transporter. Based on similar results obtained using TAP mutants lacking tapasin binding to either N domain, we conclude that all three tapasin-binding sites in TAP cooperate to achieve high transporter stability and efficient heterodimerization.
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- 2014
5. Efficient Gene Disruption in Cultured Primary Human Endothelial Cells by CRISPR/Cas9
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George Tellides, William G. Chang, W. Mark Saltzman, Jordan S. Pober, Parwiz Abrahimi, Yibing Qyang, and Martin S. Kluger
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CD4-Positive T-Lymphocytes ,Physiology ,Genes, MHC Class II ,Primary Cell Culture ,Genetic Vectors ,Vesicular Transport Proteins ,Cell Separation ,Mice, SCID ,Biology ,Major histocompatibility complex ,Lymphocyte Activation ,Article ,Mice ,Gene Knockout Techniques ,CRISPR ,Animals ,Humans ,Gene ,Cells, Cultured ,Endothelial Progenitor Cells ,CRISPR interference ,Cas9 ,Lentivirus ,Intracellular Signaling Peptides and Proteins ,Proteins ,Nuclear Proteins ,HLA-DR Antigens ,Tetracycline ,Fetal Blood ,Molecular biology ,Cell culture ,biology.protein ,Trans-Activators ,Female ,Lymphocyte Culture Test, Mixed ,CRISPR-Cas Systems ,Cardiology and Cardiovascular Medicine ,Gene Deletion - Abstract
Rationale: The participation of endothelial cells (EC) in many physiological and pathological processes is widely modeled using human EC cultures, but genetic manipulation of these untransformed cells has been technically challenging. Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 nuclease (Cas9) technology offers a promising new approach. However, mutagenized cultured cells require cloning to yield homogeneous populations, and the limited replicative lifespan of well-differentiated human EC presents a barrier for doing so. Objective: To create a simple but highly efficient method using CRISPR/Cas9 to generate biallelic gene disruption in untransformed human EC. Methods and Results: To demonstrate proof-of-principle, we used CRISPR/Cas9 to disrupt the gene for the class II transactivator. We used endothelial colony forming cell–derived EC and lentiviral vectors to deliver CRISPR/Cas9 elements to ablate EC expression of class II major histocompatibility complex molecules and with it, the capacity to activate allogeneic CD4 + T cells. We show the observed loss-of-function arises from biallelic gene disruption in class II transactivator that leaves other essential properties of the cells intact, including self-assembly into blood vessels in vivo, and that the altered phenotype can be rescued by reintroduction of class II transactivator expression. Conclusions: CRISPR/Cas9-modified human EC provides a powerful platform for vascular research and for regenerative medicine/tissue engineering.
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- 2015
6. Blood Vessels in Allotransplantation
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Jordan S. Pober, Parwiz Abrahimi, and Rebecca Liu
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Graft Rejection ,Pathology ,medicine.medical_specialty ,Endothelium ,medicine.medical_treatment ,Ischemia ,Inflammation ,Immune system ,medicine ,Immunology and Allergy ,Humans ,Transplantation, Homologous ,Pharmacology (medical) ,Fibrinoid necrosis ,Transplantation ,business.industry ,Graft Survival ,Organ Transplantation ,medicine.disease ,Acquired immune system ,Prognosis ,surgical procedures, operative ,medicine.anatomical_structure ,Immunology ,Blood Vessels ,medicine.symptom ,business ,Reperfusion injury ,Allotransplantation - Abstract
Human vascularized allografts are perfused through blood vessels composed of cells (endothelium, pericytes, and smooth muscle cells) that remain largely of graft origin and are thus subject to host alloimmune responses. Graft vessels must be healthy to maintain homeostatic functions including control of perfusion, maintenance of permselectivity, prevention of thrombosis, and participation in immune surveillance. Vascular cell injury can cause dysfunction that interferes with these processes. Graft vascular cells can be activated by mediators of innate and adaptive immunity to participate in graft inflammation contributing to both ischemia/reperfusion injury and allograft rejection. Different forms of rejection may affect graft vessels in different ways, ranging from thrombosis and neutrophilic inflammation in hyperacute rejection, to endothelialitis/intimal arteritis and fibrinoid necrosis in acute cell-mediated or antibody-mediated rejection, respectively, and to diffuse luminal stenosis in chronic rejection. While some current therapies targeting the host immune system do affect graft vascular cells, direct targeting of the graft vasculature may create new opportunities for preventing allograft injury and loss.
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- 2014
7. Sustained delivery of proangiogenic microRNA-132 by nanoparticle transfection improves endothelial cell transplantation
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Dan Jane-wit, Parwiz Abrahimi, William G. Chang, Christopher J. Cheng, W. Mark Saltzman, Jillian W. Andrejecsk, Julie Devalliere, and Jordan S. Pober
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Integrin ,Blotting, Western ,Neovascularization, Physiologic ,Mice, SCID ,Transfection ,Biochemistry ,Umbilical vein ,Research Communications ,chemistry.chemical_compound ,Mice ,Tissue engineering ,Genetics ,Human Umbilical Vein Endothelial Cells ,Animals ,Humans ,Nanotechnology ,Molecular Biology ,Microscopy, Confocal ,biology ,Tissue Engineering ,Reverse Transcriptase Polymerase Chain Reaction ,Flow Cytometry ,Molecular biology ,Cell biology ,Endothelial stem cell ,Transplantation ,PLGA ,MicroRNAs ,chemistry ,biology.protein ,Nanoparticles ,Female ,Intracellular ,Biotechnology - Abstract
Transplantation of endothelial cells (ECs) for therapeutic vascularization or tissue engineering is a promising method for increasing tissue perfusion. Here, we report on a new approach for enhanced EC transplantation using targeted nanoparticle transfection to deliver proangiogenic microRNA-132 (miR-132) to cultured ECs before their transplantation, thereby sensitizing cells to the effects of endogenous growth factors. We synthesized biodegradable PLGA polymer nanoparticles (NPs) that were loaded with miR-132 and coated with cyclic RGD (cRGD) peptides that target integrin αvβ3 expressed on cultured human umbilical vein ECs (HUVECs), increasing NP uptake through clathrin-coated pits. Unlike previously reported NPs for miR delivery, these NPs slowly release RNA for several weeks. The endocytosed NPs remain in clathrin-coated vesicles from which they mediate intracellular delivery of siRNA or miRNA. Transfection of HUVECs with miR-132 enhances growth factor-induced proliferation and migration in 2D culture, producing a 1.8- and 5-fold increase, respectively. However, while the effects of conventional transfection were short-lived, NP transfection produced protein knockdown and biological effects that were significantly longer in duration (≥6 d). Transfection of HUVECs with miR-132 NP resulted in a 2-fold increase in the number of microvessels per square millimeter compared to lipid after transplantation into immunodeficient mice and led to a higher number of mural cell-invested vessels than control transfection. These data suggest that sustained delivery of miR-132 encapsulated in a targeted biodegradable polymer NP is a safe and efficient strategy to improve EC transplantation and vascularization.—Devalliere, J., Chang, W. G., Andrejecsk, J. W., Abrahimi, P., Cheng, C. J., Jane-wit, D., Saltzman, W. M., Pober, J. S. Sustained delivery of proangiogenic microRNA-132 by nanoparticle transfection improves endothelial cell transplantation.
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- 2013
8. Alloantibody and Complement Promote T Cell-Mediated Cardiac Allograft Vasculopathy through Non-Canonical NF-κB Signaling in Endothelial Cells
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Pamela Clark, Gilbert W. Moeckel, Julie Devalliere, Parwiz Abrahimi, Sanjay Kulkarni, Tai Yi, Nancy C. Kirkiles-Smith, Jordan S. Pober, Thomas D. Manes, George Tellides, Lingfeng Qin, and Dan Jane-wit
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Endothelium ,medicine.medical_treatment ,T cell ,Mice, SCID ,Article ,Mice ,Isoantibodies ,T-Lymphocyte Subsets ,Physiology (medical) ,medicine ,Human Umbilical Vein Endothelial Cells ,Animals ,Humans ,Secretion ,Cells, Cultured ,Heart transplantation ,business.industry ,NF-kappa B ,Endothelial Cells ,Arteriosclerosis ,Complement System Proteins ,medicine.disease ,NFKB1 ,Allografts ,Coronary Vessels ,Transplantation ,medicine.anatomical_structure ,Immunology ,Heterografts ,Female ,Signal transduction ,Cardiology and Cardiovascular Medicine ,business ,Signal Transduction - Abstract
Background— Cardiac allograft vasculopathy is the major cause of late allograft loss after heart transplantation. Cardiac allograft vasculopathy lesions contain alloreactive T cells that secrete interferon-γ, a vasculopathic cytokine, and occur more frequently in patients with donor-specific antibody. Pathological interactions between these immune effectors, representing cellular and humoral immunity, respectively, remain largely unexplored. Methods and Results— We used human panel reactive antibody to form membrane attack complexes on allogeneic endothelial cells in vitro and in vivo. Rather than inducing cytolysis, membrane attack complexes upregulated inflammatory genes, enhancing the capacity of endothelial cells to recruit and activate allogeneic interferon-γ––producing CD4 + T cells in a manner dependent on the activation of noncanonical nuclear factor-κB signaling. Noncanonical nuclear factor-κB signaling was detected in situ within endothelial cells both in renal biopsies from transplantation patients with chronic antibody-mediated rejection and in panel-reactive antibody––treated human coronary artery xenografts in immunodeficient mice. On retransplantation into immunodeficient hosts engrafted with human T cells, panel-reactive antibody––treated grafts recruited more interferon-γ––producing T cells and enhanced cardiac allograft vasculopathy lesion formation. Conclusions— Alloantibody and complement deposition on graft endothelial cells activates noncanonical nuclear factor-κB signaling, initiating a proinflammatory gene program that enhances alloreactive T cell activation and development of cardiac allograft vasculopathy. Noncanonical nuclear factor-κB signaling in endothelial cells, observed in human allograft specimens and implicated in lesion pathogenesis, may represent a target for new pharmacotherapies to halt the progression of cardiac allograft vasculopathy.
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- 2013
9. Effect Of CaVβ Subunits On Structural Organization Of CaV1.2 Calcium Channels As Revealed By Three-color Fret Microscopy
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Sam Thomas, Qizong Lao, JoBeth Harry, Nikolai M. Soldatov, Evgeny Kobrinsky, Parwiz Abrahimi, and Chirag Patel
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0303 health sciences ,Cell type ,biology ,Voltage-dependent calcium channel ,Protein subunit ,Biophysics ,Cav1.2 ,Cell biology ,03 medical and health sciences ,0302 clinical medicine ,Förster resonance energy transfer ,Membrane ,Cytoplasm ,Intramolecular force ,biology.protein ,030217 neurology & neurosurgery ,030304 developmental biology - Abstract
Voltage-gated Cav1.2 calcium channels play a crucial role in Ca2+ signaling. The poreforming α1C subunit is regulated by accessory Cavβ and α2δ subunits. Cavβ's are cytoplasmic proteins of various size encoded by four different genes (Cavβ1 - β4). Here we investigated the effect of three major Cavβ types, β1b, β2d and β3, on the structure of Cav1.2 by measuring inter and intramolecular distances between α1C and β in the plasma membrane of COS1 cells using three-color FRET microscopy. The results show that Cav1.2 channels are in close proximity in the plasma membrane. The presence of different Cavβ's does not result in significant differences in intramolecular distance between the termini of α1C, but significantly affects intermolecular distance between the termini of neighbor α1C subunits, which varies from 67 A (β1b) to 79 A (β3). Thus, our results show conclusively that plasma-membrane density of Cav1.2 channels depends on the type of Cavβ's present, suggesting a possible mechanism contributing to differences in Ca2+ signaling between various cell types.
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