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Shan SW, Do CW, Lam TC, Li HL, Stamer WD, To CH. Thrombospondin-1 mediates Rho-kinase inhibitor-induced increase in outflow-facility. J Cell Physiol 2021; 236:8226-8238. [PMID: 34180057 PMCID: PMC9292191 DOI: 10.1002/jcp.30492] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 05/24/2021] [Accepted: 06/08/2021] [Indexed: 12/30/2022]
Abstract
Rho‐kinase (ROCK) inhibitors, a novel class of anti‐glaucoma agents, act by increasing the aqueous humor outflow through the conventional trabecular meshwork pathway. However, the downstream signaling consequences of the ROCK inhibitor are not completely understood. Our data show that Y39983, a selective ROCK inhibitor, could induce filamentous actin remodeling, reduced cell motility (as measured by cell migration), and transepithelial resistance in primary human TM (hTM) cells. After 2 days Y39983 treatment of hTM cells, a proteomic study identified 20 proteins whose expression was significantly altered. Pathway analysis of those proteins revealed the involvement of the p53 pathway, integrin signaling pathway, and cytoskeletal pathway regulation by Rho GTPase. Thrombospondin‐1 (TSP1), a matricellular protein that is increased in glaucoma patients, was downregulated fivefold following Y39983 treatment. More importantly, both TSP1 antagonist leucine–serine–lysine–leucine (LSKL) and small interfering RNA (siRNA) reduced TSP1 gene and protein expressions as well as hTM cell migration. In the presence of Y39983, no further inhibition of cell migration resulted after LSKL and TSP1 siRNA knockdown. Likewise, LSKL triggered a dose‐dependent increase in outflow facility in ex vivo mouse eyes, to a similar extent as Y39983 (83.8% increase by Y39983 vs. 71.2% increase by LSKL at 50 µM). There were no additive effects with simultaneous treatment with LSKL and Y39983, supporting the notion that the effects of ROCK inhibition were mediated by TSP1.
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Affiliation(s)
- Sze-Wan Shan
- Laboratory of Experimental Optometry, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
| | - Chi-Wai Do
- Laboratory of Experimental Optometry, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China.,Centre for Eye and Vision Research, Hong Kong, China
| | - Thomas Chuen Lam
- Laboratory of Experimental Optometry, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China.,Centre for Eye and Vision Research, Hong Kong, China.,The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, Guangdong, China
| | - Hoi-Lam Li
- Laboratory of Experimental Optometry, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina, USA.,Department of Biomedical Engineering, Duke University, Durham, North Carolina, USA
| | - Chi-Ho To
- Laboratory of Experimental Optometry, School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China.,Centre for Eye and Vision Research, Hong Kong, China
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Gunning P, O'Neill G, Hardeman E. Tropomyosin-based regulation of the actin cytoskeleton in time and space. Physiol Rev 2008; 88:1-35. [PMID: 18195081 DOI: 10.1152/physrev.00001.2007] [Citation(s) in RCA: 352] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Tropomyosins are rodlike coiled coil dimers that form continuous polymers along the major groove of most actin filaments. In striated muscle, tropomyosin regulates the actin-myosin interaction and, hence, contraction of muscle. Tropomyosin also contributes to most, if not all, functions of the actin cytoskeleton, and its role is essential for the viability of a wide range of organisms. The ability of tropomyosin to contribute to the many functions of the actin cytoskeleton is related to the temporal and spatial regulation of expression of tropomyosin isoforms. Qualitative and quantitative changes in tropomyosin isoform expression accompany morphogenesis in a range of cell types. The isoforms are segregated to different intracellular pools of actin filaments and confer different properties to these filaments. Mutations in tropomyosins are directly involved in cardiac and skeletal muscle diseases. Alterations in tropomyosin expression directly contribute to the growth and spread of cancer. The functional specificity of tropomyosins is related to the collaborative interactions of the isoforms with different actin binding proteins such as cofilin, gelsolin, Arp 2/3, myosin, caldesmon, and tropomodulin. It is proposed that local changes in signaling activity may be sufficient to drive the assembly of isoform-specific complexes at different intracellular sites.
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Affiliation(s)
- Peter Gunning
- Oncology Research Unit, The Children's Hospital at Westmead, and Muscle Development Unit, Children's Medical Research Institute, Westmead; New South Wales, Australia.
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Miller T, Szczesna D, Housmans PR, Zhao J, de Freitas F, Gomes AV, Culbreath L, McCue J, Wang Y, Xu Y, Kerrick WG, Potter JD. Abnormal contractile function in transgenic mice expressing a familial hypertrophic cardiomyopathy-linked troponin T (I79N) mutation. J Biol Chem 2001; 276:3743-55. [PMID: 11060294 DOI: 10.1074/jbc.m006746200] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
This study characterizes a transgenic animal model for the troponin T (TnT) mutation (I79N) associated with familial hypertrophic cardiomyopathy. To study the functional consequences of this mutation, we examined a wild type and two I79N-transgenic mouse lines of human cardiac TnT driven by a murine alpha-myosin heavy chain promoter. Extensive characterization of the transgenic I79N lines compared with wild type and/or nontransgenic mice demonstrated: 1) normal survival and no cardiac hypertrophy even with chronic exercise; 2) large increases in Ca(2+) sensitivity of ATPase activity and force in skinned fibers; 3) a substantial increase in the rate of force activation and an increase in the rate of force relaxation; 4) lower maximal force/cross-sectional area and ATPase activity; 5) loss of sensitivity to pH-induced shifts in the Ca(2+) dependence of force; and 6) computer simulations that reproduced experimental observations and suggested that the I79N mutation decreases the apparent off rate of Ca(2+) from troponin C and increases cross-bridge detachment rate g. Simulations for intact living fibers predict a higher basal contractility, a faster rate of force development, slower relaxation, and increased resting tension in transgenic I79N myocardium compared with transgenic wild type. These mechanisms may contribute to mortality in humans, especially in stimulated contractile states.
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Affiliation(s)
- T Miller
- University of Miami School of Medicine, Departments of Molecular and Cellular Pharmacology and Physiology and Biophysics, Miami, Florida 33136 and the Department of Anesthesiology, Mayo Foundation, Rochester, Minnesota 55905
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Abstract
Gain- and loss-of-function strategies using transgenic over-expression and targeted ablation of candidate genes in in the mouse have provided important mechanistic insights into cardiovascular development, physiology and disease. An essential, but challenging step is the functional analysis of the resultant phenotype. The methods described in this review permit the study of integrated cardiovascular physiology in the adult mouse. A critical review of the available in vivo methods that assay cardiac volume (echocardiography, conductance volumetry, sonomicrometry, magnetic resonance imaging) pressure (micromanometers), flow (Doppler echocardiography), and bioelectricity (electrophysiologic studies) are presented.
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Affiliation(s)
- B D Hoit
- Department of Medicine, University Hospitals of Cleveland and Case Western Reserve University, Cleveland, Ohio, USA.
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