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Smith MA, Blankman E, Jensen CC, Hoffman LM, Ullman KS, Beckerle MC. Nuclear pore complexes concentrate on Actin/LINC/Lamin nuclear lines in response to mechanical stress in a SUN1 dependent manner. Heliyon 2022; 8:e12147. [PMID: 36619427 PMCID: PMC9816990 DOI: 10.1016/j.heliyon.2022.e12147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 11/14/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022] Open
Abstract
Formation of robust actomyosin stress fibers (SF) in response to cell stretch plays a key role in the transfer of information from the cytoplasm into the nucleus. Actin/LINC/Lamin (ALL) nuclear lines provide mechanical linkage between the actin cytoskeleton and the lamin nucleoskeleton across the nuclear envelope. To understand the establishment of ALL lines, we used live cell imaging of cells exposed to cyclic stretch. We discovered that nuclear pore complexes (NPCs) concentrate along ALL lines that are generated in response to uniaxial cyclic stretch. The ALL-associated NPCs display increased fluorescence intensity of nucleoporins Pom121, TPR and Nup153 relative to nucleoporins that are distal to the ALL lines. Here we test the hypothesis that a LINC complex component of ALL lines, SUN1 is involved in the integration of NPCs with ALL lines. We generated CRISPR SUN1 knockdown and knockout cell lines and show that SUN1 is essential for normal integration of NPCs to ALL lines. Loss or elimination of SUN1 significantly diminishes NPC/ALL line integration, demonstrating a key role for SUN1 in the recruitment or stabilization of NPCs to a discrete subdomain of the nuclear envelope at ALL lines. This work provides new insight into the mechanism by which cells respond to mechanical force through nuclear envelope remodeling.
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Affiliation(s)
- Mark A. Smith
- University of Utah Health Huntsman Cancer Institute, Salt Lake City, UT 84112, United States
- Department of Biology, Salt Lake City, UT 84112, United States
| | - Elizabeth Blankman
- University of Utah Health Huntsman Cancer Institute, Salt Lake City, UT 84112, United States
| | - Christopher C. Jensen
- University of Utah Health Huntsman Cancer Institute, Salt Lake City, UT 84112, United States
| | - Laura M. Hoffman
- University of Utah Health Huntsman Cancer Institute, Salt Lake City, UT 84112, United States
- Department of Biology, Salt Lake City, UT 84112, United States
| | - Katharine S. Ullman
- University of Utah Health Huntsman Cancer Institute, Salt Lake City, UT 84112, United States
| | - Mary C. Beckerle
- University of Utah Health Huntsman Cancer Institute, Salt Lake City, UT 84112, United States
- Department of Biology, Salt Lake City, UT 84112, United States
- Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112, United States
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LaJoie D, Turkmen AM, Mackay DR, Jensen CC, Aksenova V, Niwa M, Dasso M, Ullman KS. A role for Nup153 in nuclear assembly reveals differential requirements for targeting of nuclear envelope constituents. Mol Biol Cell 2022; 33:ar117. [PMID: 36044344 PMCID: PMC9634965 DOI: 10.1091/mbc.e22-05-0189] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Assembly of the nucleus following mitosis requires rapid and coordinate recruitment of diverse constituents to the inner nuclear membrane. We have identified an unexpected role for the nucleoporin Nup153 in promoting the continued addition of a subset of nuclear envelope (NE) proteins during initial expansion of nascent nuclei. Specifically, disrupting the function of Nup153 interferes with ongoing addition of B-type lamins, lamin B receptor, and SUN1 early in telophase, after the NE has initially enclosed chromatin. In contrast, effects on lamin A and SUN2 were minimal, pointing to differential requirements for the ongoing targeting of NE proteins. Further, distinct mistargeting phenotypes arose among the proteins that require Nup153 for NE targeting. Thus, disrupting the function of Nup153 in nuclear formation reveals several previously undescribed features important for establishing nuclear architecture: 1) a role for a nuclear basket constituent in ongoing recruitment of nuclear envelope components, 2) two functionally separable phases of NE formation in mammalian cells, and 3) distinct requirements of individual NE residents for continued targeting during the expansion phase of NE reformation.
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Affiliation(s)
- Dollie LaJoie
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112
| | - Ayse M. Turkmen
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112
| | - Douglas R. Mackay
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112
| | - Christopher C. Jensen
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112
| | - Vasilisa Aksenova
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Maho Niwa
- Division of Biological Sciences, Section of Molecular Biology, University of California, San Diego, La Jolla, CA 92093
| | - Mary Dasso
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
| | - Katharine S. Ullman
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112,*Address correspondence to: Katharine S. Ullman (
.edu)
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Hoffman LM, Jensen CC, Beckerle MC. Phosphorylation of the small heat shock protein HspB1 regulates cytoskeletal recruitment and cell motility. Mol Biol Cell 2022; 33:ar100. [PMID: 35767320 DOI: 10.1091/mbc.e22-02-0057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The small heat shock protein HspB1, also known as Hsp25/27, is a ubiquitously expressed molecular chaperone that responds to mechanical cues. Uniaxial cyclic stretch activates the p38 mitogen-activated protein kinase (MAPK) signaling cascade and increases the phosphorylation of HspB1. Similar to the mechanosensitive cytoskeletal regulator zyxin, phospho-HspB1 is recruited to features of the stretch-stimulated actin cytoskeleton. To evaluate the role of HspB1 and its phosphoregulation in modulating cell function, we utilized CRISPR/Cas9-edited HspB1-null cells and determined they were altered in behaviors such as actin cytoskeletal remodeling, cell spreading, and cell motility. In our model system, expression of WT HspB1, but not nonphosphorylatable HspB1, rescued certain characteristics of the HspB1-null cells including the enhanced cell motility of HspB1-null cells and the deficient actin reinforcement of stretch-stimulated HspB1-null cells. The recruitment of HspB1 to high-tension structures in geometrically constrained cells, such as actin comet tails emanating from focal adhesions, also required a phosphorylatable HspB1. We show that mechanical signals activate posttranslational regulation of the molecular chaperone, HspB1, and are required for normal cell behaviors including actin cytoskeletal remodeling, cell spreading, and cell migration.
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Affiliation(s)
- Laura M Hoffman
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112.,Department of Biology, University of Utah, Salt Lake City, UT 84112
| | | | - Mary C Beckerle
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112.,Department of Biology, University of Utah, Salt Lake City, UT 84112.,Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112
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4
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Hoffman LM, Smith MA, Jensen CC, Yoshigi M, Blankman E, Ullman KS, Beckerle MC. Mechanical stress triggers nuclear remodeling and the formation of transmembrane actin nuclear lines with associated nuclear pore complexes. Mol Biol Cell 2020; 31:1774-1787. [PMID: 31967947 PMCID: PMC7521858 DOI: 10.1091/mbc.e19-01-0027] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Mechanical stimulation of fibroblasts induces changes in the actin cytoskeleton including stress fiber (SF) reinforcement and realignment. Here we characterize the nuclear response to mechanical stimulation (uniaxial cyclic stretch). Using fluorescence microscopy and quantitative image analysis we find that stretch-induced nuclear elongation and alignment perpendicular to the stretch vector are dependent on formin-regulated actin polymerization. The mechanosensitive transcription factors Yes-associated protein/Transcriptional coactivator with PDZ domain (YAP/TAZ) and myocardin-related transcription factor (MRTF-A, also known as MKL1 and MAL1) accumulate in the nucleus and activate their target genes in response to uniaxial cyclic stretch. We show that transmembrane actin nuclear (TAN) lines are induced by stretch stimulation and nuclear envelope (NE) proteins including nesprins, SUN2, and lamins form Linkers of the Nucleoskeleton and Cytoskeleton (LINC) complexes aligned with actin SFs. These NE structures are altered by pharmacological treatments (Cytochalasin D and Jasplakinolide) or genetic disruption (zyxin gene deletion) that alter actin, and their persistence requires maintenance of stretch stimulation. Nuclear pore complexes (NPCs) accumulate at TAN lines providing a potential mechanism for linking mechanical cues to NPC function.
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Affiliation(s)
- Laura M Hoffman
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112.,Department of Biology, University of Utah, Salt Lake City, UT 84112
| | - Mark A Smith
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112.,Department of Biology, University of Utah, Salt Lake City, UT 84112
| | | | - Masaaki Yoshigi
- Department of Pediatrics, University of Utah, Salt Lake City, UT 84112
| | | | - Katharine S Ullman
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112.,Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112
| | - Mary C Beckerle
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112.,Department of Biology, University of Utah, Salt Lake City, UT 84112.,Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112
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5
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Hoffman L, Jensen CC, Yoshigi M, Beckerle M. Mechanical signals activate p38 MAPK pathway-dependent reinforcement of actin via mechanosensitive HspB1. Mol Biol Cell 2017; 28:2661-2675. [PMID: 28768826 PMCID: PMC5620374 DOI: 10.1091/mbc.e17-02-0087] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 07/24/2017] [Accepted: 07/28/2017] [Indexed: 01/12/2023] Open
Abstract
Mechanical force induces protein phosphorylations, subcellular redistributions, and actin remodeling. We show that mechanical activation of the p38 MAPK pathway leads to phosphorylation of HspB1 (hsp25/27), which redistributes to cytoskeletal structures, and contributes to the actin cytoskeletal remodeling induced by mechanical stimulation. Despite the importance of a cell’s ability to sense and respond to mechanical force, the molecular mechanisms by which physical cues are converted to cell-instructive chemical information to influence cell behaviors remain to be elucidated. Exposure of cultured fibroblasts to uniaxial cyclic stretch results in an actin stress fiber reinforcement response that stabilizes the actin cytoskeleton. p38 MAPK signaling is activated in response to stretch, and inhibition of p38 MAPK abrogates stretch-induced cytoskeletal reorganization. Here we show that the small heat shock protein HspB1 (hsp25/27) is phosphorylated in stretch-stimulated mouse fibroblasts via a p38 MAPK-dependent mechanism. Phosphorylated HspB1 is recruited to the actin cytoskeleton, displaying prominent accumulation on actin “comet tails” that emanate from focal adhesions in stretch-stimulated cells. Site-directed mutagenesis to block HspB1 phosphorylation inhibits the protein’s cytoskeletal recruitment in response to mechanical stimulation. HspB1-null cells, generated by CRISPR/Cas9 nuclease genome editing, display an abrogated stretch-stimulated actin reinforcement response and increased cell migration. HspB1 is recruited to sites of increased traction force in cells geometrically constrained on micropatterned substrates. Our findings elucidate a molecular pathway by which a mechanical signal is transduced via activation of p38 MAPK to influence actin remodeling and cell migration via a zyxin-independent process.
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Affiliation(s)
- Laura Hoffman
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112.,Department of Biology, University of Utah, Salt Lake City, UT 84112
| | | | - Masaaki Yoshigi
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112.,Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112
| | - Mary Beckerle
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112 .,Department of Biology, University of Utah, Salt Lake City, UT 84112.,Department of Pediatrics, University of Utah, Salt Lake City, UT 84112
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Rosner SR, Pascoe CD, Blankman E, Jensen CC, Krishnan R, James AL, Elliot JG, Green FH, Liu JC, Seow CY, Park JA, Beckerle MC, Paré PD, Fredberg JJ, Smith MA. The actin regulator zyxin reinforces airway smooth muscle and accumulates in airways of fatal asthmatics. PLoS One 2017; 12:e0171728. [PMID: 28278518 PMCID: PMC5344679 DOI: 10.1371/journal.pone.0171728] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 01/24/2017] [Indexed: 01/21/2023] Open
Abstract
Bronchospasm induced in non-asthmatic human subjects can be easily reversed by a deep inspiration (DI) whereas bronchospasm that occurs spontaneously in asthmatic subjects cannot. This physiological effect of a DI has been attributed to the manner in which a DI causes airway smooth muscle (ASM) cells to stretch, but underlying molecular mechanisms-and their failure in asthma-remain obscure. Using cells and tissues from wild type and zyxin-/- mice we report responses to a transient stretch of physiologic magnitude and duration. At the level of the cytoskeleton, zyxin facilitated repair at sites of stress fiber fragmentation. At the level of the isolated ASM cell, zyxin facilitated recovery of contractile force. Finally, at the level of the small airway embedded with a precision cut lung slice, zyxin slowed airway dilation. Thus, at each level zyxin stabilized ASM structure and contractile properties at current muscle length. Furthermore, when we examined tissue samples from humans who died as the result of an asthma attack, we found increased accumulation of zyxin compared with non-asthmatics and asthmatics who died of other causes. Together, these data suggest a biophysical role for zyxin in fatal asthma.
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Affiliation(s)
- Sonia R. Rosner
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Christopher D. Pascoe
- University of British Columbia Center for Heart Lung Innovation, St Paul Hospital, Vancouver, British Columbia, Canada
| | - Elizabeth Blankman
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, United States of America
| | - Christopher C. Jensen
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, United States of America
| | - Ramaswamy Krishnan
- Center for Vascular Biology Research, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States of America
| | - Alan L. James
- Department of Pulmonary Physiology and Sleep Medicine, West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, West Australia, Australia
- School of Medicine and Pharmacology, University of Western Australia, Perth, Western Australia, Australia
| | - John G. Elliot
- Department of Pulmonary Physiology and Sleep Medicine, West Australian Sleep Disorders Research Institute, Sir Charles Gairdner Hospital, Nedlands, West Australia, Australia
| | - Francis H. Green
- Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Jeffrey C. Liu
- University of British Columbia Center for Heart Lung Innovation, St Paul Hospital, Vancouver, British Columbia, Canada
| | - Chun Y. Seow
- University of British Columbia Center for Heart Lung Innovation, St Paul Hospital, Vancouver, British Columbia, Canada
| | - Jin-Ah Park
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Mary C. Beckerle
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, United States of America
- Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
| | - Peter D. Paré
- University of British Columbia Center for Heart Lung Innovation, St Paul Hospital, Vancouver, British Columbia, Canada
| | - Jeffrey J. Fredberg
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, United States of America
| | - Mark A. Smith
- Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah, United States of America
- Department of Biology, University of Utah, Salt Lake City, Utah, United States of America
- * E-mail:
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7
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Abstract
No patient benefit yet
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Affiliation(s)
- C C Jensen
- Division of Colon and Rectal Surgery, University of Minnesota, MMC 450, 420 Delaware Street SE, Minneapolis, Minnesota 55455, USA
| | - R D Madoff
- Division of Colon and Rectal Surgery, University of Minnesota, MMC 450, 420 Delaware Street SE, Minneapolis, Minnesota 55455, USA.
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8
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Chaturvedi A, Hoffman LM, Jensen CC, Lin YC, Grossmann AH, Randall RL, Lessnick SL, Welm AL, Beckerle MC. Molecular dissection of the mechanism by which EWS/FLI expression compromises actin cytoskeletal integrity and cell adhesion in Ewing sarcoma. Mol Biol Cell 2014; 25:2695-709. [PMID: 25057021 PMCID: PMC4161506 DOI: 10.1091/mbc.e14-01-0007] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Ewing sarcoma is the second-most-common bone cancer in children. Driven by an oncogenic chromosomal translocation that results in the expression of an aberrant transcription factor, EWS/FLI, the disease is typically aggressive and micrometastatic upon presentation. Silencing of EWS/FLI in patient-derived tumor cells results in the altered expression of hundreds to thousands of genes and is accompanied by dramatic morphological changes in cytoarchitecture and adhesion. Genes encoding focal adhesion, extracellular matrix, and actin regulatory proteins are dominant targets of EWS/FLI-mediated transcriptional repression. Reexpression of genes encoding just two of these proteins, zyxin and α5 integrin, is sufficient to restore cell adhesion and actin cytoskeletal integrity comparable to what is observed when the EWS/FLI oncogene expression is compromised. Using an orthotopic xenograft model, we show that EWS/FLI-induced repression of α5 integrin and zyxin expression promotes tumor progression by supporting anchorage-independent cell growth. This selective advantage is paired with a tradeoff in which metastatic lung colonization is compromised.
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Affiliation(s)
- Aashi Chaturvedi
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112 Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112
| | - Laura M Hoffman
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112 Department of Biology, University of Utah, Salt Lake City, UT 84112
| | | | - Yi-Chun Lin
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112 Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112
| | - Allie H Grossmann
- Department of Pathology, University of Utah, Salt Lake City, UT 84112
| | - R Lor Randall
- Center for Children's Cancer Research, Huntsman Cancer Institute, Division of Pediatric Hematology/Oncology, University of Utah School of Medicine, Salt Lake City, UT 84132 Department of Orthopaedics, Sarcoma Services, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112
| | - Stephen L Lessnick
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112 Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112 Center for Children's Cancer Research, Huntsman Cancer Institute, Division of Pediatric Hematology/Oncology, University of Utah School of Medicine, Salt Lake City, UT 84132
| | - Alana L Welm
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112 Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112
| | - Mary C Beckerle
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112 Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112 Department of Biology, University of Utah, Salt Lake City, UT 84112
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Hoffman LM, Jensen CC, Chaturvedi A, Yoshigi M, Beckerle MC. Stretch-induced actin remodeling requires targeting of zyxin to stress fibers and recruitment of actin regulators. Mol Biol Cell 2012; 23:1846-59. [PMID: 22456508 PMCID: PMC3350550 DOI: 10.1091/mbc.e11-12-1057] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Mechanical stimulation induces zyxin-dependent actin cytoskeletal reinforcement. Stretch induces MAPK activation, zyxin phosphorylation, and recruitment to actin stress fibers, independent of p130Cas. Zyxin's C-terminal LIM domains are required for stretch-induced targeting to stress fibers, and zyxin's N-terminus is necessary for actin remodeling. Reinforcement of actin stress fibers in response to mechanical stimulation depends on a posttranslational mechanism that requires the LIM protein zyxin. The C-terminal LIM region of zyxin directs the force-sensitive accumulation of zyxin on actin stress fibers. The N-terminal region of zyxin promotes actin reinforcement even when Rho kinase is inhibited. The mechanosensitive integrin effector p130Cas binds zyxin but is not required for mitogen-activated protein kinase–dependent zyxin phosphorylation or stress fiber remodeling in cells exposed to uniaxial cyclic stretch. α-Actinin and Ena/VASP proteins bind to the stress fiber reinforcement domain of zyxin. Mutation of their docking sites reveals that zyxin is required for recruitment of both groups of proteins to regions of stress fiber remodeling. Zyxin-null cells reconstituted with zyxin variants that lack either α-actinin or Ena/VASP-binding capacity display compromised response to mechanical stimulation. Our findings define a bipartite mechanism for stretch-induced actin remodeling that involves mechanosensitive targeting of zyxin to actin stress fibers and localized recruitment of actin regulatory machinery.
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Affiliation(s)
- Laura M Hoffman
- Departments of Biology and Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA
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10
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Abstract
Zyxin is a dual-function LIM domain protein that regulates actin dynamics in response to mechanical stress and shuttles between focal adhesions and the cell nucleus. Here we show that zyxin contributes to UV-induced apoptosis. Exposure of wild-type fibroblasts to UV-C irradiation results in apoptotic cell death, whereas cells harboring a homozygous disruption of the zyxin gene display a statistically significant survival advantage. To gain insight into the molecular mechanism by which zyxin promotes apoptotic signaling, we expressed an affinity-tagged zyxin variant in zyxin-null cells and isolated zyxin-associated proteins from cell lysates under physiological conditions. A 130-kDa protein that was co-isolated with zyxin was identified by microsequence analysis as the Cell Cycle and Apoptosis Regulator Protein-1 (CARP-1). CARP-1 associates with the LIM region of zyxin. Zyxin lacking the CARP-1 binding region shows reduced proapoptotic activity in response to UV-C irradiation. We demonstrate that CARP-1 is a nuclear protein. Zyxin is modified by phosphorylation in cells exposed to UV-C irradiation, and nuclear accumulation of zyxin is induced by UV-C exposure. These findings highlight a novel mechanism for modulating the apoptotic response to UV irradiation.
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Affiliation(s)
- Martial Hervy
- Huntsman Cancer Institute, Departments of Biology and Oncological Sciences, University of Utah, Salt Lake City, UT, USA
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Hoffman LM, Jensen CC, Kloeker S, Wang CLA, Yoshigi M, Beckerle MC. Genetic ablation of zyxin causes Mena/VASP mislocalization, increased motility, and deficits in actin remodeling. ACTA ACUST UNITED AC 2006; 172:771-82. [PMID: 16505170 PMCID: PMC2063708 DOI: 10.1083/jcb.200512115] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Focal adhesions are specialized regions of the cell surface where integrin receptors and associated proteins link the extracellular matrix to the actin cytoskeleton. To define the cellular role of the focal adhesion protein zyxin, we characterized the phenotype of fibroblasts in which the zyxin gene was deleted by homologous recombination. Zyxin-null fibroblasts display enhanced integrin-dependent adhesion and are more migratory than wild-type fibroblasts, displaying reduced dependence on extracellular matrix cues. We identified differences in the profiles of 75- and 80-kD tyrosine-phosphorylated proteins in the zyxin-null cells. Tandem array mass spectrometry identified both modified proteins as isoforms of the actomyosin regulator caldesmon, a protein known to influence contractility, stress fiber formation, and motility. Zyxin-null fibroblasts also show deficits in actin stress fiber remodeling and exhibit changes in the molecular composition of focal adhesions, most notably by severely reduced accumulation of Ena/VASP proteins. We postulate that zyxin cooperates with Ena/VASP proteins and caldesmon to influence integrin-dependent cell motility and actin stress fiber remodeling.
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Affiliation(s)
- Laura M Hoffman
- The Huntsman Cancer Institute and the Department of Biology,University of Utah, Salt Lake City, UT 84112, USA
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12
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Yoshigi M, Hoffman LM, Jensen CC, Yost HJ, Beckerle MC. Mechanical force mobilizes zyxin from focal adhesions to actin filaments and regulates cytoskeletal reinforcement. ACTA ACUST UNITED AC 2006; 171:209-15. [PMID: 16247023 PMCID: PMC2171187 DOI: 10.1083/jcb.200505018] [Citation(s) in RCA: 283] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Organs and tissues adapt to acute or chronic mechanical stress by remodeling their actin cytoskeletons. Cells that are stimulated by cyclic stretch or shear stress in vitro undergo bimodal cytoskeletal responses that include rapid reinforcement and gradual reorientation of actin stress fibers; however, the mechanism by which cells respond to mechanical cues has been obscure. We report that the application of either unidirectional cyclic stretch or shear stress to cells results in robust mobilization of zyxin from focal adhesions to actin filaments, whereas many other focal adhesion proteins and zyxin family members remain at focal adhesions. Mechanical stress also induces the rapid zyxin-dependent mobilization of vasodilator-stimulated phosphoprotein from focal adhesions to actin filaments. Thickening of actin stress fibers reflects a cellular adaptation to mechanical stress; this cytoskeletal reinforcement coincides with zyxin mobilization and is abrogated in zyxin-null cells. Our findings identify zyxin as a mechanosensitive protein and provide mechanistic insight into how cells respond to mechanical cues.
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Affiliation(s)
- Masaaki Yoshigi
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
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Hoffman LM, Nix DA, Benson B, Boot-Hanford R, Gustafsson E, Jamora C, Menzies AS, Goh KL, Jensen CC, Gertler FB, Fuchs E, Fässler R, Beckerle MC. Targeted disruption of the murine zyxin gene. Mol Cell Biol 2003; 23:70-9. [PMID: 12482962 PMCID: PMC140673 DOI: 10.1128/mcb.23.1.70-79.2003] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Zyxin is an evolutionarily conserved protein that is concentrated at sites of cell adhesion, where it associates with members of the Enabled (Ena)/vasodilator-stimulated phosphoprotein (VASP) family of cytoskeletal regulators and is postulated to play a role in cytoskeletal dynamics and signaling. Zyxin transcripts are detected throughout murine embryonic development, and the protein is widely expressed in adults. Here we used a reverse genetic approach to examine the consequences of loss of zyxin function in the mouse. Mice that lack zyxin function are viable and fertile and display no obvious histological abnormalities in any of the organs examined. Because zyxin contributes to the localization of Ena/VASP family members at certain subcellular locations, we carefully examined the zyxin(-/-) mice for evidence of defects that have been observed when Ena/VASP proteins are compromised in the mouse. Specifically, we evaluated blood platelet function, nervous system development, and skin architecture but did not detect any defects in these systems. Zyxin is the founding member of a family of proteins that also includes the lipoma preferred partner (LPP) and thyroid receptor-interacting protein 6 (TRIP6). These zyxin family members display patterns of expression that significantly overlap that of zyxin. Western blot analysis indicates that there is no detectable upregulation of either LPP or TRIP6 expression in tissues derived from zyxin-null mice. Because zyxin family members may have overlapping functions, a comprehensive understanding of the role of these proteins in the mouse will require the generation of compound mutations in which multiple zyxin family members are simultaneously compromised.
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Affiliation(s)
- Laura M Hoffman
- Huntsman Cancer Institute and Department of Biology, University of Utah, Salt Lake City 84112, USA
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Yi J, Kloeker S, Jensen CC, Bockholt S, Honda H, Hirai H, Beckerle MC. Members of the Zyxin family of LIM proteins interact with members of the p130Cas family of signal transducers. J Biol Chem 2002; 277:9580-9. [PMID: 11782456 DOI: 10.1074/jbc.m106922200] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Integrin binding to extracellular matrix proteins induces formation of signaling complexes at focal adhesions. Zyxin co-localizes with integrins at sites of cell-substratum adhesion and is postulated to serve as a docking site for the assembly of multimeric protein complexes involved in regulating cell motility. Recently, we identified a new member of the zyxin family called TRIP6. TRIP6 is localized at focal adhesions and overexpression of TRIP6 slows cell migration. In an effort to define the molecular mechanism by which TRIP6 affects cell migration, the yeast two-hybrid assay was employed to identify proteins that directly bind to TRIP6. This assay revealed that both TRIP6 and zyxin interact with CasL/HEF1, a member of the Cas family. This association is mediated by the LIM region of the zyxin family members and the SH2 domain-binding region of CasL/HEF1. Furthermore, the association between p130(Cas) and the two zyxin family members was demonstrated to occur in vivo by co-immunoprecipitation. Zyxin and Cas family members may cooperate to regulate cell motility.
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Affiliation(s)
- Jinseong Yi
- Huntsman Cancer Institute and Department of Biology, University of Utah, Salt Lake City, Utah 84112 and the University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
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Matilla A, Gorbea C, Einum DD, Townsend J, Michalik A, van Broeckhoven C, Jensen CC, Murphy KJ, Ptácek LJ, Fu YH. Association of ataxin-7 with the proteasome subunit S4 of the 19S regulatory complex. Hum Mol Genet 2001; 10:2821-31. [PMID: 11734547 DOI: 10.1093/hmg/10.24.2821] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Spinocerebellar ataxia type 7 (SCA7) is a neurodegenerative disorder characterized by ataxia and selective neuronal cell loss caused by the expansion of a translated CAG repeat encoding a polyglutamine tract in ataxin-7, the SCA7 gene product. To gain insight into ataxin-7 function and to decipher the molecular mechanisms of neurodegeneration in SCA7, a two-hybrid assay was performed to identify ataxin-7 interacting proteins. Herein, we show that ataxin-7 interacts with the ATPase subunit S4 of the proteasomal 19S regulatory complex. The ataxin-7/S4 association is modulated by the length of the polyglutamine tract whereby S4 shows a stronger association with the wild-type allele of ataxin-7. We demonstrate that endogenous ataxin-7 localizes to discrete nuclear foci that also contain additional components of the proteasomal complex. Immunohistochemical analyses suggest alterations either of the distribution or the levels of S4 immunoreactivity in neurons that degenerate in SCA7 brains. Immunoblot analyses demonstrate reduced levels of S4 in SCA7 cerebella without evident alterations in the levels of other proteasome subunits. These results suggest a role for S4 and ubiquitin-mediated proteasomal proteolysis in the molecular pathogenesis of SCA7.
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Affiliation(s)
- A Matilla
- Howard Hughes Medical Institute, University of Utah, Salt Lake City, UT 84112-5331, USA
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16
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Dewald CL, Jensen CC, Park YH, Hanks SE, Harrell DS, Peters GL, Katz MD. Vena cavography with CO(2) versus with iodinated contrast material for inferior vena cava filter placement: a prospective evaluation. Radiology 2000; 216:752-7. [PMID: 10966706 DOI: 10.1148/radiology.216.3.r00au15752] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE To determine whether carbon dioxide (CO(2)) vena cavography can safely guide the placement of inferior vena cava (IVC) filters. MATERIALS AND METHODS One hundred nineteen patients were prospectively enrolled in this study. CO(2 )cavograms were obtained and evaluated for IVC diameter, location of renal veins, and presence of thrombus and venous anomalies. If CO(2 )cavography was judged to be adequate, an IVC filter was deployed. After filter placement, cavography was performed with iodinated contrast material; these images were compared with the CO(2) cavograms. RESULTS Two patients experienced mild side effects related to venous CO(2) injection. Comparison of cavograms obtained with CO(2) and iodinated contrast-enhanced material showed the caval size to be within 3 mm in all 119 patients. In 116 patients (97.5%), CO(2) cavography was judged to be adequate, and in 115 patients, filters were placed. In three (2.5%) patients, it was necessary to perform iodinated contrast-enhanced cavography before filter deployment. All six cases of venous anomaly and 11 (78.6%) of 14 cases of thrombosis were clearly identified with CO(2) cavography. One filter was maldeployed owing to misinterpretation of the CO(2) cavogram. CONCLUSION CO(2) cavography is well tolerated, safe, and adequate for identification of the parameters necessary for filter deployment. It is especially valuable in patients with a history of reaction to iodinated contrast material or renal insufficiency.
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Affiliation(s)
- C L Dewald
- Department of Radiology, Division of Vascular and Interventional Radiology, Los Angeles County-University of Southern California Medical Center, CA 90033, USA
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Abstract
The purpose of this study was to review our institutional experience with colorflow duplex scanning in detecting significant renal artery stenosis and to validate the criteria used: renal artery peak systolic velocity (PSV) >/=200 cm/sec and renal-to-aortic peak systolic ratio (RAR) >/=3.5. The results of renal artery duplex and arteriography in 58 patients (107 kidneys) who underwent both exams were reviewed. Arteriography revealed 32 main renal arteries with >/=60% stenosis. The PSV criterion detected 29, for a sensitivity of 91%, specificity of 75%, positive predictive value (PPV) of 60%, negative predictive value (NPV) of 95%, and accuracy of 79%. Using RAR >/=3.5 provided a sensitivity of 72%, specificity of 92%, PPV of 79%, NPV of 88%, and accuracy of 86%. In a subset of 36 kidneys that had hilar scans, the criteria of acceleration time (AT) >/=100 cm/sec and index (AI) </=3.78 kHz/sec were evaluated. The AT and AI yielded sensitivity of 50% and 36%, specificity of 86% and 100%, PPV of 70% and 100%, NPV of 73% and 71%, and accuracy of 72% and 75%, respectively. Colorflow duplex scanning is clinically useful in screening for hemodynamically significant renal artery stenosis. The renal artery PSV criterion is highly sensitive, with a high NPV that obviates the need for arteriography in most cases of a negative duplex. The criteria of RAR, AT, and AI are of less value.
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Affiliation(s)
- H T Hua
- Department of Surgery, Division of Vascular Surgery, University of Southern California, School of Medicine, Los Angeles, CA, USA
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Zhang Z, Clawson A, Realini C, Jensen CC, Knowlton JR, Hill CP, Rechsteiner M. Identification of an activation region in the proteasome activator REGalpha. Proc Natl Acad Sci U S A 1998; 95:2807-11. [PMID: 9501171 PMCID: PMC19650 DOI: 10.1073/pnas.95.6.2807] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Proteasomes can be markedly activated by associating with 19S regulatory complexes to form the 26S protease or by binding 11S protein complexes known as REG or PA28. Three REG subunits, alpha, beta, and gamma, have been expressed in Escherichia coli, and each recombinant protein can activate human proteasomes. Combining PCR mutagenesis with an in vitro activity assay, we have isolated and characterized 36 inactive, single-site mutants of recombinant REGalpha. Most are monomers that produce functional proteasome activators when mixed with REGbeta subunits. Five REGalpha mutants that remain inactive in the mixing assay contain amino acid substitutions clustered between Arg-141 and Gly-149. The crystal structure of the REGalpha heptamer shows that this region forms a loop at the base of each REGalpha subunit. One mutation in this loop (N146Y) yields a REGalpha heptamer that binds the proteasome as tightly as wild-type REGalpha but does not activate peptide hydrolysis. Corresponding amino acid substitutions in REGbeta (N135Y) and REGgamma (N151Y) produce inactive proteins that also bind the proteasome and inhibit proteasome activation by their normal counterparts. Our studies clearly demonstrate that REG binding to the proteasome can be separated from activation of the enzyme. Moreover, the dominant negative REGs identified here should prove valuable for elucidating the role(s) of these proteins in antigen presentation.
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Affiliation(s)
- Z Zhang
- Department of Biochemistry, University of Utah, 50 North Medical Drive, Salt Lake City, UT 84132, USA
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Realini C, Jensen CC, Zhang Z, Johnston SC, Knowlton JR, Hill CP, Rechsteiner M. Characterization of recombinant REGalpha, REGbeta, and REGgamma proteasome activators. J Biol Chem 1997; 272:25483-92. [PMID: 9325261 DOI: 10.1074/jbc.272.41.25483] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Full-length cDNAs for three human proteasome activator subunits, called REGalpha, REGbeta, and REGgamma, have been expressed in Escherichia coli, and the purified recombinant proteins have been characterized. Recombinant alpha or gamma subunits form heptameric species; recombinant beta subunits are found largely as monomers or small multimers. Each recombinant REG stimulates cleavage of fluorogenic peptides by human red cell proteasomes. The pattern of activated peptide hydrolysis is virtually identical for REGalpha and REGbeta. These two subunits, alone or in combination, stimulate cleavage after basic, acidic, and most hydrophobic residues in many peptides. Recombinant alpha and beta subunits bind each other with high affinity, and the REGalpha/beta heteromeric complex activates hydrolysis of LLVY-methylcoumaryl-7-amide (LLVY-MCA) and LLE-beta-nitroanilide (LLE-betaNA) more than REGalpha or REGbeta alone. Using filter binding and gel filtration assays, recombinant REGgamma subunits were shown to bind themselves but not alpha or beta subunits. REGgamma differs from REGalpha and REGbeta in that it markedly stimulates hydrolysis of peptides with basic residues in the P1 position but only modestly activates cleavage of LLVY-MCA or LLE-betaNA by the proteasome. REGgamma binds the proteasome with higher affinity than REGalpha or REGbeta yet with lower affinity than complexes containing both REGalpha and REGbeta. In summary, each of the three REG homologs is a proteasome activator with unique biochemical properties.
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Affiliation(s)
- C Realini
- Department of Biochemistry, University of Utah School of Medicine, Salt Lake City, Utah 84132, USA
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Abstract
The saturation properties of an UV laser dye, 3,5,3,5-tetra-t-butyl-p-sexiphenyl (TBS), pumped by a XeCl laser were studied. The experimental data included measurements of the optical saturation of transmission and amplifier gain. The data were fit directly to photon propagation differential equations to obtain the saturation intensities for absorption and emission. From the measured saturation parameters a complete determination was made of the optical constants of the singlet states in TBS. The results presented include the absorption spectrum, fluorescence spectrum, fluorescence lifetime, excitedstate absorption cross sections at the pump laser and dye laser wavelengths, quantum yield, wavelength dependence of the stimulated emission cross section, and an upper bound for the intersystem crossing rate. The saturation analysis method provides a rapid experimental evaluation of a laser dye with high accuracy. A two-photon excited transition at the long wavelengths of the laser oscillator tuning range of TBS produces photochemical degradation. The photochemical degradation rate increases with increasing wavelength.
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Abstract
A detailed coagulation and thromboelastographic study was done on the first 50 liver transplantation procedures performed at the Mayo Clinic between March 1985 and June 1986. Most of the patients suffered from primary sclerosing cholangitis, primary biliary cirrhosis, or chronic active hepatitis. Seven patients required a second liver transplantation, and six patients died, none intraoperatively. Most of the patients had distorted hemostatic mechanisms preoperatively, as would be expected because the liver generates most of the clotting factors. The outstanding exception was factor VIII, which was usually in the high-normal range or even more elevated. Substantial deterioration of coagulation factors occurred regularly during reperfusion of the donor liver. In some instances, this trend was corrected within 1 hour, but platelet counts continued to decrease, and some coagulation factors rebounded only partially. Because thromboelastographic tracings are quickly available to the liver transplant team and because they tend to forewarn of impending hemostatic problems, we believe that thromboelastography is a reasonably effective procedure for monitoring coagulation during liver transplantation.
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Heidorn SD, Jensen CC. Generalization and maintenance of the reduction of self-injurious behavior maintained by two types of reinforcement. Behav Res Ther 1984; 22:581-6. [PMID: 6508708 DOI: 10.1016/0005-7967(84)90062-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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