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Anush Oganesian - One of the best experts on this subject based on the ideXlab platform.

  • alpha1a adrenoceptor Genetic Variant triggers vascular smooth muscle cell hyperproliferation and agonist induced hypertrophy via egfr transactivation pathway
    PLOS ONE, 2015
    Co-Authors: Irina Gradinaru, Ekaterina Babaeva, Debra A Schwinn, Anush Oganesian
    Abstract:

    α1a Adrenergic receptors (α1aARs) are the predominant AR subtype in human vascular smooth muscle cells (SMCs). α1aARs in resistance vessels are crucial in the control of blood pressure, yet the impact of naturally occurring human α1aAR Genetic Variants in cardiovascular disorders remains poorly understood. To this end, we present novel findings demonstrating that 3D cultures of vascular SMCs expressing human α1aAR-247R (247R) Genetic Variant demonstrate significantly increased SMC contractility compared with cells expressing the α1aAR-WT (WT) receptor. Stable expression of 247R Genetic Variant also triggers MMP/EGFR-transactivation dependent serum- and agonist-independent (constitutive) hyperproliferation and agonist-dependent hypertrophy of SMCs. Agonist stimulation reduces contractility Using pathway-specific inhibitors we determined that the observed hyperproliferation of 247R-expressing cells is triggered via β-arrestin1/Src/MMP-2/EGFR/ERK-dependent mechanism. MMP-2-specific siRNA inhibited 247R-triggered hyperproliferation indicating MMP-2 involvement in 247R-triggered hyperproliferation in SMCs. β-arrestin1-specific shRNA also inhibited 247R-triggered hyperproliferation but did not affect hypertrophy in 247R-expressing SMCs, indicating that agonist-dependent hypertrophy is independent of β-arrestin1. Our data reveal that in different cardiovascular cells the same human receptor Genetic Variant can activate alternative modulators of the same signaling pathway. Thus, our findings in SMCs demonstrate that depending on the type of cells expressing the same receptor (or receptor Variant), different target-specific inhibitors could be used to modulate aberrant hyperproliferative or hypertrophic pathways in order to restore normal phenotype.

  • abstract 052 alpha1a adrenoceptor Genetic Variant triggered hyperproliferation in cardiovascular cells is mediated by novel interacting protein spinophilin
    Hypertension, 2014
    Co-Authors: Ekaterina Babaeva, Irina Gradinaru, Debra A Schwinn, Anush Oganesian
    Abstract:

    Objectives: Alpha1-Adrenergic Receptors (α1ARs), members of the G protein-coupled receptor (GPCR) superfamily, play a major role in regulating cardiovascular (CV) function. Recently, we discovered that naturally occurring human α1aAR-G247R (247R) Genetic Variant, identified in the 3rd intracellular loop (3iL) of the receptor in highly hypertensive patient, triggers constitutive hyperproliferation in fibroblasts, cardiomyoblasts and smooth muscle cells (SMC). Specific proteins mediating this signaling remain unknown. Spinophilin (SPL) is a ubiquitously expressed protein controlling GPCR signaling by binding its 3rd intracellular loop (3iL). We hypothesize that SPL mediates α1aAR signaling and examined whether SPL directly interacts with α1aAR-WT (WT) and 247R. Methods: Cells were co-transfected with HA-α1ARs and full length Myc-SPL or its fragments to determine SPL domains responsible for binding to α1ARs. Cell lysates were co-immunoprecipitated with HA-tag antibodies. SPL levels were analyzed by Western blotting. SPL knockdown experiments were performed by transiently transfecting cells with SPL or scrambled siRNA, cell proliferation was determined by cell counting. Results: We demonstrate a distinct interaction of SPL with WT and 247R, WT interaction being the strongest. Different domains of SPL differentially interact with WT or 247R. SPL 1-480aa fragment interacts stronger with WT indicating interaction with 3iL, while SPL 480-817 fragment interacts stronger with 247R. Endogenous SPL levels are increased in 247R cells compared to WT or control cells. Inhibition of SPL expression in SMC with siRNA reduces 247R-triggered hyperproliferation to near normal levels and has no effect in WT cells. Conclusions: We identified SPL as a novel interacting protein involved in mediating intracellular signaling of α1aAR and its Genetic Variant in CV cells. Different domains of SPL differentially bind to WT or 247R indicating that SPL has a distinct role in regulation of their signaling pathways. Our findings also reveal that SPL is critical for 247R-triggered EGFR transactivation pathways. Thus SPL could be considered as a potentially novel target in α1aAR-mediated cardiovascular disorders.

  • abstract 200 novel interaction of spinophilin with alpha1a adrenergic receptor and its Genetic Variant in cardiovascular cells
    Circulation Research, 2014
    Co-Authors: Ekaterina Babaeva, Irina Gradinaru, Debra A Schwinn, Anush Oganesian
    Abstract:

    Activation of α1-Adrenergic Receptors (α1ARs), members of the G protein-coupled receptor (GPCR) superfamily, in response to stimulation of the sympathetic nervous system by catecholamines plays a major role in regulating cardiovascular (CV) function. Among three α1AR subtypes (α1a,α1b,α1d), α1aARs predominate in human resistant vessels and in heart. Recently, we discovered that naturally occurring human α1aAR-G247R (247R) Genetic Variant, identified in the 3rd intracellular loop (3iL) of the receptor in highly hypertensive patient, triggers constitutive hyperproliferation in CV cells (cardiomyoblasts, smooth muscle cells (SMC) and fibroblasts), which may lead to myocardial fibrosis and remodeling. In fibroblasts and cardiomyoblasts 247R triggered hyperproliferation is due to constitutive active coupling to Gq-independent βarrestin1/MMP/EGFR/ERK dependent pathway, while in SMC it is Gq- and MMP/EGFR/ERK-dependent. Here we report that α1aAR-WT (WT) and 247R differentially interact with ubiquitous multi-doma...

  • abstract 348 α1a adrenoceptor Genetic Variant triggered hyperproliferation is mediated through aberrant interaction with spinophilin in smooth muscle cells
    Arteriosclerosis Thrombosis and Vascular Biology, 2014
    Co-Authors: Ekaterina Babaeva, Irina Gradinaru, Debra A Schwinn, Anush Oganesian
    Abstract:

    Activation of α1-Adrenergic Receptors (α1ARs), members of the G protein-coupled receptor (GPCR) superfamily, in response to stimulation of the sympathetic nervous system by catecholamines plays a major role in regulating cardiovascular (CV) function and blood pressure (BP). Among three α1AR subtypes (α1a,α1b,α1d) expressed in vasculature α1aARs predominate in human vascular smooth muscle cells (SMC), particularly in resistant vessels most involved in BP control. Polymorphisms in the α1aAR gene are also related to hypertension (HTN), one of the major CV risk factors. Recently, we discovered a novel, unique mechanism of hypertension triggered by naturally occurring human α1aAR-G247R (247R) Genetic Variant, identified in the 3rd intracellular loop (3iL) of the receptor in hypertensive patient. In fibroblasts, 247R signals via constitutive active coupling to the βarrestin1/MMP7/EGFR pathway. Here we report that 247R expression in SMC triggers constitutive, Gq- and MMP/EGFR/ERK-dependent hyperproliferation. Agonist (phenylephrine) treatment of cells inhibits hyperproliferation and induces hypertrophy and α1aAR inverse agonist prazosin inhibits hyperproliferation and hypertrophy indicating Gq-dependent pathway. Expression of 247R in SMC also triggers upregulation of spinophilin (SPL), a ubiquitous multi-domain scaffold protein that binds to 3iL of several GPCRs and competes with βarrestins for 3iL binding. We hypothesized that SPL mediates constitutive signaling of 247R and examined whether SPL directly interacts with α1aAR-WT or 247R. Our preliminary results demonstrate a distinct interaction of α1aAR-WT and 247R with SPL, although the SPL-α1AR-WT interaction appears to be strongest. SPL 1-480aa fragment demonstrates stronger interaction with α1aAR-WT indicating that this domain is responsible for interaction with 3iL. Interestingly the SPL 480-817 fragment has stronger interaction with 247R. Thus, expression of the naturally occurring human α1aAR Genetic Variant in vascular cells activates distinct signaling pathways leading to aberrant hyperproliferation and hypertrophy, and may eventually result in hypertension and other CV diseases suggesting a possible novel mechanism underlying some forms of human hypertension.

Ekaterina Babaeva - One of the best experts on this subject based on the ideXlab platform.

  • alpha1a adrenoceptor Genetic Variant triggers vascular smooth muscle cell hyperproliferation and agonist induced hypertrophy via egfr transactivation pathway
    PLOS ONE, 2015
    Co-Authors: Irina Gradinaru, Ekaterina Babaeva, Debra A Schwinn, Anush Oganesian
    Abstract:

    α1a Adrenergic receptors (α1aARs) are the predominant AR subtype in human vascular smooth muscle cells (SMCs). α1aARs in resistance vessels are crucial in the control of blood pressure, yet the impact of naturally occurring human α1aAR Genetic Variants in cardiovascular disorders remains poorly understood. To this end, we present novel findings demonstrating that 3D cultures of vascular SMCs expressing human α1aAR-247R (247R) Genetic Variant demonstrate significantly increased SMC contractility compared with cells expressing the α1aAR-WT (WT) receptor. Stable expression of 247R Genetic Variant also triggers MMP/EGFR-transactivation dependent serum- and agonist-independent (constitutive) hyperproliferation and agonist-dependent hypertrophy of SMCs. Agonist stimulation reduces contractility Using pathway-specific inhibitors we determined that the observed hyperproliferation of 247R-expressing cells is triggered via β-arrestin1/Src/MMP-2/EGFR/ERK-dependent mechanism. MMP-2-specific siRNA inhibited 247R-triggered hyperproliferation indicating MMP-2 involvement in 247R-triggered hyperproliferation in SMCs. β-arrestin1-specific shRNA also inhibited 247R-triggered hyperproliferation but did not affect hypertrophy in 247R-expressing SMCs, indicating that agonist-dependent hypertrophy is independent of β-arrestin1. Our data reveal that in different cardiovascular cells the same human receptor Genetic Variant can activate alternative modulators of the same signaling pathway. Thus, our findings in SMCs demonstrate that depending on the type of cells expressing the same receptor (or receptor Variant), different target-specific inhibitors could be used to modulate aberrant hyperproliferative or hypertrophic pathways in order to restore normal phenotype.

  • abstract 052 alpha1a adrenoceptor Genetic Variant triggered hyperproliferation in cardiovascular cells is mediated by novel interacting protein spinophilin
    Hypertension, 2014
    Co-Authors: Ekaterina Babaeva, Irina Gradinaru, Debra A Schwinn, Anush Oganesian
    Abstract:

    Objectives: Alpha1-Adrenergic Receptors (α1ARs), members of the G protein-coupled receptor (GPCR) superfamily, play a major role in regulating cardiovascular (CV) function. Recently, we discovered that naturally occurring human α1aAR-G247R (247R) Genetic Variant, identified in the 3rd intracellular loop (3iL) of the receptor in highly hypertensive patient, triggers constitutive hyperproliferation in fibroblasts, cardiomyoblasts and smooth muscle cells (SMC). Specific proteins mediating this signaling remain unknown. Spinophilin (SPL) is a ubiquitously expressed protein controlling GPCR signaling by binding its 3rd intracellular loop (3iL). We hypothesize that SPL mediates α1aAR signaling and examined whether SPL directly interacts with α1aAR-WT (WT) and 247R. Methods: Cells were co-transfected with HA-α1ARs and full length Myc-SPL or its fragments to determine SPL domains responsible for binding to α1ARs. Cell lysates were co-immunoprecipitated with HA-tag antibodies. SPL levels were analyzed by Western blotting. SPL knockdown experiments were performed by transiently transfecting cells with SPL or scrambled siRNA, cell proliferation was determined by cell counting. Results: We demonstrate a distinct interaction of SPL with WT and 247R, WT interaction being the strongest. Different domains of SPL differentially interact with WT or 247R. SPL 1-480aa fragment interacts stronger with WT indicating interaction with 3iL, while SPL 480-817 fragment interacts stronger with 247R. Endogenous SPL levels are increased in 247R cells compared to WT or control cells. Inhibition of SPL expression in SMC with siRNA reduces 247R-triggered hyperproliferation to near normal levels and has no effect in WT cells. Conclusions: We identified SPL as a novel interacting protein involved in mediating intracellular signaling of α1aAR and its Genetic Variant in CV cells. Different domains of SPL differentially bind to WT or 247R indicating that SPL has a distinct role in regulation of their signaling pathways. Our findings also reveal that SPL is critical for 247R-triggered EGFR transactivation pathways. Thus SPL could be considered as a potentially novel target in α1aAR-mediated cardiovascular disorders.

  • abstract 200 novel interaction of spinophilin with alpha1a adrenergic receptor and its Genetic Variant in cardiovascular cells
    Circulation Research, 2014
    Co-Authors: Ekaterina Babaeva, Irina Gradinaru, Debra A Schwinn, Anush Oganesian
    Abstract:

    Activation of α1-Adrenergic Receptors (α1ARs), members of the G protein-coupled receptor (GPCR) superfamily, in response to stimulation of the sympathetic nervous system by catecholamines plays a major role in regulating cardiovascular (CV) function. Among three α1AR subtypes (α1a,α1b,α1d), α1aARs predominate in human resistant vessels and in heart. Recently, we discovered that naturally occurring human α1aAR-G247R (247R) Genetic Variant, identified in the 3rd intracellular loop (3iL) of the receptor in highly hypertensive patient, triggers constitutive hyperproliferation in CV cells (cardiomyoblasts, smooth muscle cells (SMC) and fibroblasts), which may lead to myocardial fibrosis and remodeling. In fibroblasts and cardiomyoblasts 247R triggered hyperproliferation is due to constitutive active coupling to Gq-independent βarrestin1/MMP/EGFR/ERK dependent pathway, while in SMC it is Gq- and MMP/EGFR/ERK-dependent. Here we report that α1aAR-WT (WT) and 247R differentially interact with ubiquitous multi-doma...

  • abstract 348 α1a adrenoceptor Genetic Variant triggered hyperproliferation is mediated through aberrant interaction with spinophilin in smooth muscle cells
    Arteriosclerosis Thrombosis and Vascular Biology, 2014
    Co-Authors: Ekaterina Babaeva, Irina Gradinaru, Debra A Schwinn, Anush Oganesian
    Abstract:

    Activation of α1-Adrenergic Receptors (α1ARs), members of the G protein-coupled receptor (GPCR) superfamily, in response to stimulation of the sympathetic nervous system by catecholamines plays a major role in regulating cardiovascular (CV) function and blood pressure (BP). Among three α1AR subtypes (α1a,α1b,α1d) expressed in vasculature α1aARs predominate in human vascular smooth muscle cells (SMC), particularly in resistant vessels most involved in BP control. Polymorphisms in the α1aAR gene are also related to hypertension (HTN), one of the major CV risk factors. Recently, we discovered a novel, unique mechanism of hypertension triggered by naturally occurring human α1aAR-G247R (247R) Genetic Variant, identified in the 3rd intracellular loop (3iL) of the receptor in hypertensive patient. In fibroblasts, 247R signals via constitutive active coupling to the βarrestin1/MMP7/EGFR pathway. Here we report that 247R expression in SMC triggers constitutive, Gq- and MMP/EGFR/ERK-dependent hyperproliferation. Agonist (phenylephrine) treatment of cells inhibits hyperproliferation and induces hypertrophy and α1aAR inverse agonist prazosin inhibits hyperproliferation and hypertrophy indicating Gq-dependent pathway. Expression of 247R in SMC also triggers upregulation of spinophilin (SPL), a ubiquitous multi-domain scaffold protein that binds to 3iL of several GPCRs and competes with βarrestins for 3iL binding. We hypothesized that SPL mediates constitutive signaling of 247R and examined whether SPL directly interacts with α1aAR-WT or 247R. Our preliminary results demonstrate a distinct interaction of α1aAR-WT and 247R with SPL, although the SPL-α1AR-WT interaction appears to be strongest. SPL 1-480aa fragment demonstrates stronger interaction with α1aAR-WT indicating that this domain is responsible for interaction with 3iL. Interestingly the SPL 480-817 fragment has stronger interaction with 247R. Thus, expression of the naturally occurring human α1aAR Genetic Variant in vascular cells activates distinct signaling pathways leading to aberrant hyperproliferation and hypertrophy, and may eventually result in hypertension and other CV diseases suggesting a possible novel mechanism underlying some forms of human hypertension.

Henry Houlden - One of the best experts on this subject based on the ideXlab platform.

  • Charcot-Marie-Tooth type 4B2 demyelinating neuropathy in miniature Schnauzer dogs caused by a novel splicing SBF2 (MTMR13) Genetic Variant: a new spontaneous clinical model.
    PeerJ, 2019
    Co-Authors: Nicolas Granger, Alejandro Luján Feliu-pascual, Charlotte Spicer, Sally L. Ricketts, Rebekkah J. Hitti, Oliver P. Forman, Joshua Hersheson, Henry Houlden
    Abstract:

    Background Charcot-Marie-Tooth (CMT) disease is the most common neuromuscular disorder in humans affecting 40 out of 100,000 individuals. In 2008, we described the clinical, electrophysiological and pathological findings of a demyelinating motor and sensory neuropathy in Miniature Schnauzer dogs, with a suspected autosomal recessive mode of inheritance based on pedigree analysis. The discovery of additional cases has followed this work and led to a genome-wide association mapping approach to search for the underlying Genetic cause of the disease. Methods For genome wide association screening, genomic DNA samples from affected and unaffected dogs were genotyped using the Illumina CanineHD SNP genotyping array. SBF2 and its Variant were sequenced using primers and PCRs. RNA was extracted from muscle of an unaffected and an affected dog and RT-PCR performed. Immunohistochemistry for myelin basic protein was performed on peripheral nerve section specimens. Results The genome-wide association study gave an indicative signal on canine chromosome 21. Although the signal was not of genome-wide significance due to the small number of cases, the SBF2 (also known as MTMR13) gene within the region of shared case homozygosity was a strong positional candidate, as 22 Genetic Variants in the gene have been associated with demyelinating forms of Charcot-Marie-Tooth disease in humans. Sequencing of SBF2 in cases revealed a splice donor site Genetic Variant, resulting in cryptic splicing and predicted early termination of the protein based on RNA sequencing results. Conclusions This study reports the first Genetic Variant in Miniature Schnauzer dogs responsible for the occurrence of a demyelinating peripheral neuropathy with abnormally folded myelin. This discovery establishes a genotype/phenotype correlation in affected Miniature Schnauzers that can be used for the diagnosis of these dogs. It further supports the dog as a natural model of a human disease; in this instance, Charcot-Marie-Tooth disease. It opens avenues to search the biological mechanisms responsible for the disease and to test new therapies in a non-rodent large animal model. In particular, recent gene editing methods that led to the restoration of dystrophin expression in a canine model of muscular dystrophy could be applied to other canine models such as this before translation to humans.

Irina Gradinaru - One of the best experts on this subject based on the ideXlab platform.

  • alpha1a adrenoceptor Genetic Variant triggers vascular smooth muscle cell hyperproliferation and agonist induced hypertrophy via egfr transactivation pathway
    PLOS ONE, 2015
    Co-Authors: Irina Gradinaru, Ekaterina Babaeva, Debra A Schwinn, Anush Oganesian
    Abstract:

    α1a Adrenergic receptors (α1aARs) are the predominant AR subtype in human vascular smooth muscle cells (SMCs). α1aARs in resistance vessels are crucial in the control of blood pressure, yet the impact of naturally occurring human α1aAR Genetic Variants in cardiovascular disorders remains poorly understood. To this end, we present novel findings demonstrating that 3D cultures of vascular SMCs expressing human α1aAR-247R (247R) Genetic Variant demonstrate significantly increased SMC contractility compared with cells expressing the α1aAR-WT (WT) receptor. Stable expression of 247R Genetic Variant also triggers MMP/EGFR-transactivation dependent serum- and agonist-independent (constitutive) hyperproliferation and agonist-dependent hypertrophy of SMCs. Agonist stimulation reduces contractility Using pathway-specific inhibitors we determined that the observed hyperproliferation of 247R-expressing cells is triggered via β-arrestin1/Src/MMP-2/EGFR/ERK-dependent mechanism. MMP-2-specific siRNA inhibited 247R-triggered hyperproliferation indicating MMP-2 involvement in 247R-triggered hyperproliferation in SMCs. β-arrestin1-specific shRNA also inhibited 247R-triggered hyperproliferation but did not affect hypertrophy in 247R-expressing SMCs, indicating that agonist-dependent hypertrophy is independent of β-arrestin1. Our data reveal that in different cardiovascular cells the same human receptor Genetic Variant can activate alternative modulators of the same signaling pathway. Thus, our findings in SMCs demonstrate that depending on the type of cells expressing the same receptor (or receptor Variant), different target-specific inhibitors could be used to modulate aberrant hyperproliferative or hypertrophic pathways in order to restore normal phenotype.

  • abstract 052 alpha1a adrenoceptor Genetic Variant triggered hyperproliferation in cardiovascular cells is mediated by novel interacting protein spinophilin
    Hypertension, 2014
    Co-Authors: Ekaterina Babaeva, Irina Gradinaru, Debra A Schwinn, Anush Oganesian
    Abstract:

    Objectives: Alpha1-Adrenergic Receptors (α1ARs), members of the G protein-coupled receptor (GPCR) superfamily, play a major role in regulating cardiovascular (CV) function. Recently, we discovered that naturally occurring human α1aAR-G247R (247R) Genetic Variant, identified in the 3rd intracellular loop (3iL) of the receptor in highly hypertensive patient, triggers constitutive hyperproliferation in fibroblasts, cardiomyoblasts and smooth muscle cells (SMC). Specific proteins mediating this signaling remain unknown. Spinophilin (SPL) is a ubiquitously expressed protein controlling GPCR signaling by binding its 3rd intracellular loop (3iL). We hypothesize that SPL mediates α1aAR signaling and examined whether SPL directly interacts with α1aAR-WT (WT) and 247R. Methods: Cells were co-transfected with HA-α1ARs and full length Myc-SPL or its fragments to determine SPL domains responsible for binding to α1ARs. Cell lysates were co-immunoprecipitated with HA-tag antibodies. SPL levels were analyzed by Western blotting. SPL knockdown experiments were performed by transiently transfecting cells with SPL or scrambled siRNA, cell proliferation was determined by cell counting. Results: We demonstrate a distinct interaction of SPL with WT and 247R, WT interaction being the strongest. Different domains of SPL differentially interact with WT or 247R. SPL 1-480aa fragment interacts stronger with WT indicating interaction with 3iL, while SPL 480-817 fragment interacts stronger with 247R. Endogenous SPL levels are increased in 247R cells compared to WT or control cells. Inhibition of SPL expression in SMC with siRNA reduces 247R-triggered hyperproliferation to near normal levels and has no effect in WT cells. Conclusions: We identified SPL as a novel interacting protein involved in mediating intracellular signaling of α1aAR and its Genetic Variant in CV cells. Different domains of SPL differentially bind to WT or 247R indicating that SPL has a distinct role in regulation of their signaling pathways. Our findings also reveal that SPL is critical for 247R-triggered EGFR transactivation pathways. Thus SPL could be considered as a potentially novel target in α1aAR-mediated cardiovascular disorders.

  • abstract 200 novel interaction of spinophilin with alpha1a adrenergic receptor and its Genetic Variant in cardiovascular cells
    Circulation Research, 2014
    Co-Authors: Ekaterina Babaeva, Irina Gradinaru, Debra A Schwinn, Anush Oganesian
    Abstract:

    Activation of α1-Adrenergic Receptors (α1ARs), members of the G protein-coupled receptor (GPCR) superfamily, in response to stimulation of the sympathetic nervous system by catecholamines plays a major role in regulating cardiovascular (CV) function. Among three α1AR subtypes (α1a,α1b,α1d), α1aARs predominate in human resistant vessels and in heart. Recently, we discovered that naturally occurring human α1aAR-G247R (247R) Genetic Variant, identified in the 3rd intracellular loop (3iL) of the receptor in highly hypertensive patient, triggers constitutive hyperproliferation in CV cells (cardiomyoblasts, smooth muscle cells (SMC) and fibroblasts), which may lead to myocardial fibrosis and remodeling. In fibroblasts and cardiomyoblasts 247R triggered hyperproliferation is due to constitutive active coupling to Gq-independent βarrestin1/MMP/EGFR/ERK dependent pathway, while in SMC it is Gq- and MMP/EGFR/ERK-dependent. Here we report that α1aAR-WT (WT) and 247R differentially interact with ubiquitous multi-doma...

  • abstract 348 α1a adrenoceptor Genetic Variant triggered hyperproliferation is mediated through aberrant interaction with spinophilin in smooth muscle cells
    Arteriosclerosis Thrombosis and Vascular Biology, 2014
    Co-Authors: Ekaterina Babaeva, Irina Gradinaru, Debra A Schwinn, Anush Oganesian
    Abstract:

    Activation of α1-Adrenergic Receptors (α1ARs), members of the G protein-coupled receptor (GPCR) superfamily, in response to stimulation of the sympathetic nervous system by catecholamines plays a major role in regulating cardiovascular (CV) function and blood pressure (BP). Among three α1AR subtypes (α1a,α1b,α1d) expressed in vasculature α1aARs predominate in human vascular smooth muscle cells (SMC), particularly in resistant vessels most involved in BP control. Polymorphisms in the α1aAR gene are also related to hypertension (HTN), one of the major CV risk factors. Recently, we discovered a novel, unique mechanism of hypertension triggered by naturally occurring human α1aAR-G247R (247R) Genetic Variant, identified in the 3rd intracellular loop (3iL) of the receptor in hypertensive patient. In fibroblasts, 247R signals via constitutive active coupling to the βarrestin1/MMP7/EGFR pathway. Here we report that 247R expression in SMC triggers constitutive, Gq- and MMP/EGFR/ERK-dependent hyperproliferation. Agonist (phenylephrine) treatment of cells inhibits hyperproliferation and induces hypertrophy and α1aAR inverse agonist prazosin inhibits hyperproliferation and hypertrophy indicating Gq-dependent pathway. Expression of 247R in SMC also triggers upregulation of spinophilin (SPL), a ubiquitous multi-domain scaffold protein that binds to 3iL of several GPCRs and competes with βarrestins for 3iL binding. We hypothesized that SPL mediates constitutive signaling of 247R and examined whether SPL directly interacts with α1aAR-WT or 247R. Our preliminary results demonstrate a distinct interaction of α1aAR-WT and 247R with SPL, although the SPL-α1AR-WT interaction appears to be strongest. SPL 1-480aa fragment demonstrates stronger interaction with α1aAR-WT indicating that this domain is responsible for interaction with 3iL. Interestingly the SPL 480-817 fragment has stronger interaction with 247R. Thus, expression of the naturally occurring human α1aAR Genetic Variant in vascular cells activates distinct signaling pathways leading to aberrant hyperproliferation and hypertrophy, and may eventually result in hypertension and other CV diseases suggesting a possible novel mechanism underlying some forms of human hypertension.

Houlden H - One of the best experts on this subject based on the ideXlab platform.

  • Charcot-Marie-Tooth type 4B2 demyelinating neuropathy in miniature Schnauzer dogs caused by a novel splicing SBF2 (MTMR13) Genetic Variant: a new spontaneous clinical model
    'PeerJ', 2019
    Co-Authors: Granger N, Feliu-pascual A, Spicer C, Ricketts S, Hitti R, Forman O, Hersheson J, Houlden H
    Abstract:

    This study reports the first Genetic Variant in Miniature Schnauzer dogs responsible for the occurrence of a demyelinating peripheral neuropathy with abnormally folded myelin. This discovery establishes a genotype/phenotype correlation in affected Miniature Schnauzers that can be used for the diagnosis of these dogs. It further supports the dog as a natural model of a human disease; in this instance, Charcot-Marie-Tooth disease. It opens avenues to search the biological mechanisms responsible for the disease and to test new therapies in a non-rodent large animal model. In particular, recent gene editing methods that led to the restoration of dystrophin expression in a canine model of muscular dystrophy could be applied to other canine models such as this before translation to humans