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Dingwell LS, Shikatani EA, Besla R, Levy AS, Dinh DD, Momen A, Zhang H, Afroze T, Chen MB, Chiu F, Simmons CA, Billia F, Gommerman JL, John R, Heximer S, Scholey JW, Bolz SS, Robbins CS, Husain M. B-Cell Deficiency Lowers Blood Pressure in Mice. Hypertension 2019; 73:561-570. [DOI: 10.1161/hypertensionaha.118.11828] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Luke S. Dingwell
- From the Toronto General Hospital Research Institute, University Health Network, Canada (L.S.D., E.A.S., A.M., T.A., F.B., M.H.)
- Heart and Stroke Richard Lewar Centre of Excellence, Ted Rogers Centre for Heart Research, Peter Munk Cardiac Centre (L.S.D., E.A.S., C.S.R., M.H.), University of Toronto, Canada
- Department of the Institute of Medical Science (L.S.D., M.H.), University of Toronto, Canada
| | - Eric A. Shikatani
- From the Toronto General Hospital Research Institute, University Health Network, Canada (L.S.D., E.A.S., A.M., T.A., F.B., M.H.)
- Heart and Stroke Richard Lewar Centre of Excellence, Ted Rogers Centre for Heart Research, Peter Munk Cardiac Centre (L.S.D., E.A.S., C.S.R., M.H.), University of Toronto, Canada
- Department of Laboratory Medicine and Pathobiology (E.A.S., R.B., F.C., R.J., C.S.R., M.H.), University of Toronto, Canada
| | - Rickvinder Besla
- Department of Laboratory Medicine and Pathobiology (E.A.S., R.B., F.C., R.J., C.S.R., M.H.), University of Toronto, Canada
| | - Andrew S. Levy
- Department of Physiology (A.S.L., D.D.D., H.Z., S.H., J.W.S., S.-S.B., M.H.), University of Toronto, Canada
| | - Danny D. Dinh
- Department of Physiology (A.S.L., D.D.D., H.Z., S.H., J.W.S., S.-S.B., M.H.), University of Toronto, Canada
| | - Abdul Momen
- From the Toronto General Hospital Research Institute, University Health Network, Canada (L.S.D., E.A.S., A.M., T.A., F.B., M.H.)
| | - Hangjun Zhang
- Department of Physiology (A.S.L., D.D.D., H.Z., S.H., J.W.S., S.-S.B., M.H.), University of Toronto, Canada
| | - Talat Afroze
- From the Toronto General Hospital Research Institute, University Health Network, Canada (L.S.D., E.A.S., A.M., T.A., F.B., M.H.)
| | - Michelle B. Chen
- Department of Mechanical and Industrial Engineering (M.B.C., C.A.S.), University of Toronto, Canada
| | - Felix Chiu
- Department of Laboratory Medicine and Pathobiology (E.A.S., R.B., F.C., R.J., C.S.R., M.H.), University of Toronto, Canada
| | - Craig A. Simmons
- Department of Mechanical and Industrial Engineering (M.B.C., C.A.S.), University of Toronto, Canada
| | - Filio Billia
- From the Toronto General Hospital Research Institute, University Health Network, Canada (L.S.D., E.A.S., A.M., T.A., F.B., M.H.)
| | | | - Rohan John
- Department of Laboratory Medicine and Pathobiology (E.A.S., R.B., F.C., R.J., C.S.R., M.H.), University of Toronto, Canada
| | - Scott Heximer
- Department of Physiology (A.S.L., D.D.D., H.Z., S.H., J.W.S., S.-S.B., M.H.), University of Toronto, Canada
| | - James W. Scholey
- Department of Mechanical and Industrial Engineering (M.B.C., C.A.S.), University of Toronto, Canada
| | - Steffen-Sebastian Bolz
- Department of Mechanical and Industrial Engineering (M.B.C., C.A.S.), University of Toronto, Canada
| | - Clinton S. Robbins
- Heart and Stroke Richard Lewar Centre of Excellence, Ted Rogers Centre for Heart Research, Peter Munk Cardiac Centre (L.S.D., E.A.S., C.S.R., M.H.), University of Toronto, Canada
- Department of Laboratory Medicine and Pathobiology (E.A.S., R.B., F.C., R.J., C.S.R., M.H.), University of Toronto, Canada
- Department of Immunology (J.L.G., C.S.R.), University of Toronto, Canada
| | - Mansoor Husain
- From the Toronto General Hospital Research Institute, University Health Network, Canada (L.S.D., E.A.S., A.M., T.A., F.B., M.H.)
- Heart and Stroke Richard Lewar Centre of Excellence, Ted Rogers Centre for Heart Research, Peter Munk Cardiac Centre (L.S.D., E.A.S., C.S.R., M.H.), University of Toronto, Canada
- Department of the Institute of Medical Science (L.S.D., M.H.), University of Toronto, Canada
- Department of Laboratory Medicine and Pathobiology (E.A.S., R.B., F.C., R.J., C.S.R., M.H.), University of Toronto, Canada
- Department of Physiology (A.S.L., D.D.D., H.Z., S.H., J.W.S., S.-S.B., M.H.), University of Toronto, Canada
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2
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Oralová V, Matalová E, Janečková E, Drobná Krejčí E, Knopfová L, Šnajdr P, Tucker AS, Veselá I, Šmarda J, Buchtová M. Role of c-Myb in chondrogenesis. Bone 2015; 76:97-106. [PMID: 25845979 DOI: 10.1016/j.bone.2015.02.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 02/20/2015] [Accepted: 02/21/2015] [Indexed: 12/22/2022]
Abstract
The Myb locus encodes the c-Myb transcription factor involved in controlling a broad variety of cellular processes. Recently, it has been shown that c-Myb may play a specific role in hard tissue formation; however, all of these results were gathered from an analysis of intramembranous ossification. To investigate a possible role of c-Myb in endochondral ossification, we carried out our study on the long bones of mouse limbs during embryonic development. Firstly, the c-myb expression pattern was analyzed by in situ hybridization during endochondral ossification of long bones. c-myb positive areas were found in proliferating as well as hypertrophic zones of the growth plate. At early embryonic stages, localized expression was also observed in the perichondrium and interdigital areas. The c-Myb protein was found in proliferating chondrocytes and in the perichondrium of the forelimb bones (E14.5-E17.5). Furthermore, protein was detected in pre-hypertrophic as well as hypertrophic chondrocytes. Gain-of-function and loss-of-function approaches were used to test the effect of altered c-myb expression on chondrogenesis in micromass cultures established from forelimb buds of mouse embryos. A loss-of-function approach using c-myb specific siRNA decreased nodule formation, as well as downregulated the level of Sox9 expression, a major marker of chondrogenesis. Transient c-myb overexpression markedly increased the formation of cartilage nodules and the production of extracellular matrix as detected by intense staining with Alcian blue. Moreover, the expression of early chondrogenic genes such as Sox9, Col2a1 and activity of a Col2-LUC reporter were increased in the cells overexpressing c-myb while late chondrogenic markers such as Col10a1 and Mmp13 were not significantly changed or were downregulated. Taken together, the results of this study demonstrate that the c-Myb transcription factor is involved in the regulation and promotion of endochondral bone formation.
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Affiliation(s)
- V Oralová
- Institute of Animal Physiology and Genetics CAS, v.v.i., Brno, Czech Republic; Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic.
| | - E Matalová
- Institute of Animal Physiology and Genetics CAS, v.v.i., Brno, Czech Republic; Department of Physiology, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
| | - E Janečková
- Institute of Animal Physiology and Genetics CAS, v.v.i., Brno, Czech Republic; Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - E Drobná Krejčí
- Institute of Anatomy, Charles University, Prague, Czech Republic
| | - L Knopfová
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - P Šnajdr
- Institute of Anatomy, Charles University, Prague, Czech Republic
| | - A S Tucker
- Department of Craniofacial Development and Stem Cell Biology, King's College London, London, UK
| | - I Veselá
- Department of Anatomy, Histology and Embryology, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic
| | - J Šmarda
- Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - M Buchtová
- Institute of Animal Physiology and Genetics CAS, v.v.i., Brno, Czech Republic; Department of Experimental Biology, Faculty of Science, Masaryk University, Brno, Czech Republic
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3
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Kopecki Z, Luchetti MM, Adams DH, Strudwick X, Mantamadiotis T, Stoppacciaro A, Gabrielli A, Ramsay RG, Cowin AJ. Collagen loss and impaired wound healing is associated with c-Myb deficiency. J Pathol 2007; 211:351-61. [PMID: 17152050 DOI: 10.1002/path.2113] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Collagen type I serves as an abundant structural and signalling component of skin. It is also an established target gene of the transcription factor, c-Myb. When c-myb-/- embryos were examined it was observed that their skin was markedly thinner than normal. Importantly, immunohistochemical investigation showed complete absence of collagen type I. Although these homozygous knock-out embryos fail to develop beyond day 15, fibroblasts established from these embryos (mouse embryonic fibroblasts [MEFs]) show defective proliferative responses. Furthermore, in vitro scratch wound assays demonstrated that these c-myb-/- MEFs also exhibit slower closure than their wild-type counterparts. Embryonic lethality has meant that examination of the role of c-Myb in adult mouse skin has not been reported to date. However, in view of the abundance of collagen type I in normal skin, its role in skin integrity and the in vitro data showing proliferative and migration defects in c-myb-/- MEFs, we investigated the consequences of heterozygous c-myb loss in adult mice on the complex process of skin repair in response to injury. Our studies clearly demonstrate that heterozygous c-myb deficiency has a functional effect on wound repair, collagen type I levels and, in response to wounding, transforming growth factor-beta1 (an important collagen stimulating factor) induction expression is aberrantly high. Manipulation of c-Myb may therefore provide new therapeutic opportunities for improving wound repair while uncontrolled expression may underpin some fibrotic disorders.
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Affiliation(s)
- Z Kopecki
- Child Health Research Institute, North Adelaide, South Australia and School of Pharmacy and Medical Sciences, University of South Australia, Australia
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4
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Afroze T, Yang LL, Wang C, Gros R, Kalair W, Hoque AN, Mungrue IN, Zhu Z, Husain M. Calcineurin-independent regulation of plasma membrane Ca2+ ATPase-4 in the vascular smooth muscle cell cycle. Am J Physiol Cell Physiol 2003; 285:C88-95. [PMID: 12660151 DOI: 10.1152/ajpcell.00518.2002] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Calcineurin mediates repression of plasma membrane Ca2+-ATPase-4 (PMCA4) expression in neurons, whereas c-Myb is known to repress PMCA1 expression in vascular smooth muscle cells (VSMC). Here, we describe a novel mouse VSMC line (MOVAS) in which 45Ca efflux rates decreased 50%, fura 2-AM-based intracellular Ca2+ concentrations ([Ca2+]i) increased twofold, and real-time RT-PCR and Western blot revealed a approximately 40% decrease in PMCA4 expression levels from G0 to G1/S in the cell cycle, where PMCA4 constituted approximately 20% of total PMCA protein. Although calcineurin activity increased fivefold as MOVAS progressed from G0 to G1/S, inhibition of this increase with either BAPTA or retroviral transduction with peptide inhibitors of calcineurin (CAIN), or its downstream target nuclear factor of activated T cells (NFAT) (VIVIT), had no effect on the repression of PMCA4 mRNA expression at G1/S. By contrast, Ca2+-independent activity of the calmodulin-dependent protein kinase-II (CaMK-II) increased eightfold as MOVAS progressed from G0 to G1/S, and treatment with an inhibitor of CaMK-II (KN-93) or transduction of a c-Myb-neutralizing antibody significantly alleviated the G1/S-associated repression of PMCA4. These data show that G1/S-specific PMCA4 repression in proliferating VSMC is brought about by c-Myb and CaMK-II and that calcineurin may regulate cell cycle-associated [Ca2+]i through alternate targets.
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Affiliation(s)
- Talat Afroze
- Department of Medicine, University of Toronto, Toronto, Ontario, Canada M5G-2C4
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5
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Abstract
Bicarbonate is not freely permeable to membranes. Yet, bicarbonate must be moved across membranes, as part of CO2 metabolism and to regulate cell pH. Mammalian cells ubiquitously express bicarbonate transport proteins to facilitate the transmembrane bicarbonate flux. These bicarbonate transporters, which function by different transport mechanisms, together catalyse transmembrane bicarbonate movement. Recent advances have allowed the identification of several new bicarbonate transporter genes. Bicarbonate transporters cluster into two separate families: (i) the anion exachanger (AE) family of Cl-/HCO3- exchangers is related in sequence to the NBC family of Na+/HCO3- cotransporters and the Na(+)-dependent Cl/HCO3- exchangers and (ii) some members of the SLC26a family of sulfate transporters will also transport bicarbonate but are not related in sequence to the AE/NBC family of transporters. This review summarizes our understanding of the mammalian bicarbonate transporter superfamily.
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Affiliation(s)
- Deborah Sterling
- Department of Physiology, University of Alberta, Edmonton, Canada
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6
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You XM, Mungrue IN, Kalair W, Afroze T, Ravi B, Sadi AM, Gros R, Husain M. Conditional expression of a dominant-negative c-Myb in vascular smooth muscle cells inhibits arterial remodeling after injury. Circ Res 2003; 92:314-21. [PMID: 12595344 DOI: 10.1161/01.res.0000056758.73215.5a] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Inhibiting activity of the c-Myb transcription factor attenuates G1 to S phase cell cycle transitions in vascular smooth muscle cells (SMCs) in vitro. To determine the effects of arterial SMC-specific expression of a dominant-negative c-Myb molecule (Myb-Engrailed) on vascular remodeling in vivo, we performed carotid artery wire-denudation in 2 independent lines of binary transgenic mice with SM22alpha promoter-defined Doxycycline-suppressible expression of Myb-Engrailed. Adult mice with arterial SMC-specific expression of Myb-Engrailed were overtly normal in appearance and did not display any changes in cardiovascular structure or physiology. However, bromodeoxyuridine-defined arterial SMC proliferation, neointima formation, medial hyperplasia, and arterial remodeling were markedly decreased in mice expressing arterial SMC-restricted Myb-Engrailed after arterial injury. These data suggest that c-Myb activity in arterial SMCs is not essential for arterial structure or function during development, but is involved in the proliferation of arterial SMCs as occurs in vascular pathology, and that the expression of a dominant-negative c-Myb can dramatically reduce adverse arterial remodeling in an in vivo model of restenosis. As such, this model represents a novel tissue-specific strategy for the potential gene therapy of diseases characterized by arterial SMC proliferation.
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MESH Headings
- Animals
- Bromodeoxyuridine
- Carotid Stenosis/pathology
- Carotid Stenosis/prevention & control
- Cell Division/genetics
- Disease Models, Animal
- Gene Expression/drug effects
- Genes, Dominant
- Homeodomain Proteins/genetics
- Mice
- Mice, Transgenic
- Microfilament Proteins/genetics
- Muscle Proteins/genetics
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Promoter Regions, Genetic
- Proto-Oncogene Proteins c-myb/biosynthesis
- Proto-Oncogene Proteins c-myb/genetics
- Proto-Oncogene Proteins c-myb/pharmacology
- Tetracycline/pharmacology
- Transcription Factors
- Tunica Intima/drug effects
- Tunica Intima/metabolism
- Tunica Intima/pathology
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Affiliation(s)
- Xiao-Mang You
- Division of Cellular and Molecular Biology, The Toronto General Hospital Research Institute, Ontario, Canada
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7
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Bödding M. Reduced store-operated Ca(2+) currents in rat basophilic leukaemia cells cultured under serum-free conditions. Cell Calcium 2001; 30:141-50. [PMID: 11440471 DOI: 10.1054/ceca.2001.0222] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Influx of Ca(2+) represents an important regulatory signal in the process of cell proliferation. However, little is known about how Ca(2+) entry changes during the cell-cycle. Patch-clamp experiments and microfluorimetry show that store-operated Ca(2+) entry was substantially reduced in rat basophilic leukaemia cells cultured for 24h under serum-free conditions. Likewise, retinoic acid treatment blocked Ca(2+) influx activated by store depletion via inositol 1,4,5-trisphosphate. Both procedures are known to arrest cells at the G0/G1 boundary of the cell-cycle and induced a reduction in 5-bromo 2'-deoxyuridine incorporation into DNA. Ca(2+) release from the stores remained unaltered and two types of K(+) currents were not affected in cells after serum starvation. The specific reduction in Ca(2+) entry was not detected when using aphidicolin, 5-fluorouracil or thymidine to synchronise the cell-cycle. These data suggest that store-operated Ca(2+) influx changed during cell-cycle progression which might have important implications for cell growth.
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Affiliation(s)
- M Bödding
- University Laboratory of Physiology, Parks Road, Oxford, UK.
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8
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Afroze T, Husain M. c-Myb-binding sites mediate G(1)/S-associated repression of the plasma membrane Ca(2+)-ATPase-1 promoter. J Biol Chem 2000; 275:9062-9. [PMID: 10722757 DOI: 10.1074/jbc.275.12.9062] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We demonstrate that two Myb-binding sites of the mouse plasma membrane Ca(2+)-ATPase-1 (PMCA1) promoter are required for G(1)/S cell cycle stage-associated repression of PMCA1 promoter activity. Nuclear run-on experiments revealed G(1)/S-associated repression of PMCA1 transcription. Ribonuclease protection assays revealed two transcription initiation sites between two Myb-binding sites in the PMCA1 promoter. Gel shift assays showed that c-Myb can bind to wild-type but not point mutated Myb binding sequences of the PMCA1 promoter. Transient transfection assays using cell cycle-synchronized vascular smooth muscle cells (VSMC) and PMCA1 promoter-luciferase constructs showed a 2-fold decrease in reporter activity at G(1)/S as compared with G(0). Overexpression of wild-type c-Myb severely repressed PMCA1 promoter activity at both G(0) and G(1)/S while co-transfection of a dominant negative c-Myb, or a construct encoding an anti-c-Myb neutralizing antibody, completely abolished the repression seen at G(1)/S. Single nucleotide substitutions in the first, second, or both Myb-binding sites alleviated the G(1)/S-associated repression of PMCA1 promoter activity in transformed rat VSMC and primary mouse VSMC cultures. We conclude that c-Myb mediates G(1)/S-associated transcriptional repression of the PMCA1 Ca(2+) pump in rodent VSMC by direct binding to the PMCA1 promoter.
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Affiliation(s)
- T Afroze
- Centre for Cardiovascular Research, Toronto General Hospital, Toronto, Ontario, Canada
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9
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Golovina VA. Cell proliferation is associated with enhanced capacitative Ca(2+) entry in human arterial myocytes. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:C343-9. [PMID: 10444411 DOI: 10.1152/ajpcell.1999.277.2.c343] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Depletion of Ca(2+) stores in the sarcoplasmic reticulum (SR) activates extracellular Ca(2+) influx via capacitative Ca(2+) entry (CCE). Here, CCE levels in proliferating and growth-arrested human pulmonary artery smooth muscle cells (PASMCs) were compared by digital imaging fluorescence microscopy. Resting cytosolic free Ca(2+) concentration ([Ca(2+)](cyt)) in proliferating PASMCs was twofold higher than that in growth-arrested cells. Cyclopiazonic acid (CPA; 10 microM), which inhibits SR Ca(2+)-ATPase and depletes inositol 1,4,5-trisphosphate-sensitive Ca(2+) stores, transiently increased [Ca(2+)](cyt) in the absence of extracellular Ca(2+). The addition of 1.8 mM Ca(2+) to the extracellular solution in the presence of CPA induced large increases in [Ca(2+)](cyt), indicative of CCE. The CPA-induced SR Ca(2+) release in proliferating PASMCs was twofold higher than that in growth-arrested cells, whereas the transient rise of [Ca(2+)](cyt) due to CCE was fivefold greater in proliferating cells. CCE was insensitive to nifedipine but was significantly inhibited by 50 mM K(+), which reduces the driving force for Ca(2+) influx, and by 0.5 mM Ni(2+), a putative blocker of store-operated Ca(2+) channels. These data show that augmented CCE is associated with proliferation of human PASMCs and may be involved in stimulating and maintaining cell growth.
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Affiliation(s)
- V A Golovina
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
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10
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Abstract
For the past several years, we have been engaged in developing a therapeutically effective strategy for disrupting gene function with reverse complementary, or so called 'antisense', oligodeoxynucleotides (ODN). This pursuit has focused on finding appropriate diseases in which to apply this approach, and suitable gene targets. Of the genes that we have targeted for disruption using the antisense ODN strategy (Clevenger et al., 1995; Gewirtz and Calabretta, 1988; Ratajczak et al., 1992c; Small et al., 1994) one that has been of particular interest, and one where therapeutically motivated disruptions are now in clinical trial, is the myb gene (reviewed in Lyon et al., 1994). These trials involve treatment of human leukemias. These diseases are a logical choice for developing oncogene targeted therapies because of easy access to tissues, and the abundance of knowledge about the cell and molecular biology of these diseases. Nevertheless, as will be touched on below, other malignancies have also been examined as models for Myb targeted therapy with some surprisingly encouraging results. Finally, while we have focused our efforts on the ODN strategy, I will allude briefly to other strategies for disrupting Myb function with therapeutic intent.
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Affiliation(s)
- A M Gewirtz
- Department of Internal Medicine, Institute for Human Gene Therapy, University of Pennsylvania School of Medicine, Philadelphia 19104, USA
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11
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Abstract
Heparan sulfates in the extracellular matrix are required for a variety of biological processes, including cellular response to heparin-binding growth factors. However, little is known regarding the regulation of their expression and composition under pathophysiological conditions. In the present study, we have investigated the regulation of expression of two key heparan sulfate chain-carrying core proteins, syndecan-1 and syndecan-4, in a mouse/rat infarct model of tissue injury and repair. Induction of myocardial infarction was associated with a prompt increase in expression of both syndecan genes. Although infiltrating macrophages accounted for a substantial increase in syndecan expression, increased expression was noted in the levels of syndecan-1 mRNA in endothelial cells and syndecan-4 mRNA in cardiac myocytes. This increase in expression was limited to the immediate peri-infarct region and was absent from remote areas of the left or right ventricles. The influx of blood-derived macrophages in the heart correlated with the appearance of PR-39 peptide, which has previously been shown to increase syndecan expression in vitro. Studies in the op/op mice strain (which demonstrates sharply reduced levels of circulating monocytes) showed that myocardial infarction was associated with markedly reduced levels of macrophage influx and corresponding reduction in the expression of PR-39 and both syndecan genes. Pretreatment of op/op mice with granulocyte macrophage colony-stimulating factor restored myocardial macrophage content with corresponding restoration of PR-39/syndecan expression. In summary, myocardial infarction is associated with a distinct spatial and temporal pattern of syndecan-1 and -4 gene expression, which is induced by an influx of blood-derived macrophages.
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Affiliation(s)
- J Li
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
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12
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Husain M, Jiang L, See V, Bein K, Simons M, Alper SL, Rosenberg RD. Regulation of vascular smooth muscle cell proliferation by plasma membrane Ca(2+)-ATPase. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 272:C1947-59. [PMID: 9227424 DOI: 10.1152/ajpcell.1997.272.6.c1947] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have previously shown that reductions in c-Myb-dependent transcription inhibit cell cycle progression and decrease intracellular Ca2+ concentrations in vascular smooth muscle cells (VSMC). We now report that these effects are largely mediated by a 4- to 10-fold increased rate of La(3+)-sensitive 45Ca extrusion, which is associated with 2- to 4-fold increased levels of plasma membrane Ca(2+)-ATPase 1 (PMCA1) mRNA and protein. PMCA4 mRNA, present at much lower concentrations, undergoes similar changes during suppression of c-Myb activity. We also report that PMCA1 expression is regulated during VSMC cell cycle progression, such that levels of PMCA1 are 40% lower at the G1/S interface than at G0. Moreover, transient overexpression of PMCA1a in VSMC elevates the 45Ca efflux rate by approximately 2-fold, decreases resting and peak thapsigargin-releasable Ca2+ concentrations at G1/S by 43% (68 nM) and 52% (160 nM), respectively, and reduces the rate of cell proliferation by over 2.5-fold. These data define a mechanism for c-Myb-dependent Ca2+ homeostasis and support a critical role for PMCA in the regulation of VSMC growth.
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Affiliation(s)
- M Husain
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA
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13
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14
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Affiliation(s)
- S A Ness
- Northwestern University, Department of Biochemistry, Molecular Biology and Cell Biology, Evanston, IL 60208-3500, USA.
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15
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Hammes A, Oberdorf-Maass S, Jenatschke S, Pelzer T, Maass A, Gollnick F, Meyer R, Afflerbach J, Neyses L. Expression of the plasma membrane Ca2+-ATPase in myogenic cells. J Biol Chem 1996; 271:30816-22. [PMID: 8940063 DOI: 10.1074/jbc.271.48.30816] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
To study the physiological function of the plasma membrane calmodulin-dependent calcium ATPase (PMCA) in intact cells, L6 myogenic cell lines stably overexpressing the human PMCA isoform 4CI (= human PMCA isoform 4b) were generated. Several independent L6 clones and controls stably transfected with the empty expression vector were analyzed in detail. The resting cytosolic calcium level in hPMCA4CI-overexpressing muscle cells (measured by the Fura-2 method) was significantly reduced by 20-30% compared with controls. This was shown in a cytosolic window of 1322 single cells (p < 0.01). Furthermore, the differentiation process of these cells was remarkably accelerated compared with control myoblasts and parental nontransfected L6 cells as assessed by multinucleated myotube formation and creatine phosphokinase activity elevation. After 4 and 6 days of differentiation, PMCA-overexpressing L6 cells from four independent clones displayed a 3- and 4-fold higher creatine phosphokinase activity compared with controls (n = 5, p < 0.02). These results may extend the concept of the function of the PMCA from simple prevention of calcium overload to an active involvement in intracellular calcium regulation with potentially important consequences for cellular functions.
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Affiliation(s)
- A Hammes
- Department of Medicine, University of Würzburg, D-97080 Würzburg, Germany
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Simons M. Therapeutic manipulation of cell cycle in smooth muscle cells: implications for restenosis. THE JOURNAL OF LABORATORY AND CLINICAL MEDICINE 1996; 128:361-6. [PMID: 8833884 DOI: 10.1016/s0022-2143(96)80007-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- M Simons
- Department of Medicine, Harvard Medical School and Beth Israel Hospital, Boston, MA 02215, USA
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Affiliation(s)
- S Nikol
- Medizinische Klinik I, Klinikum Grosshadern, Ludwig-Maximilians University, Munich, Germany
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Catalioto RM, Renzetti AR, Criscuoli M, Morbidelli L, Subissi A. Role of calcium in angiotensin II-induced prostaglandin release and DNA synthesis in rat vascular smooth muscle cells. J Cardiovasc Pharmacol 1996; 27:195-200. [PMID: 8720417 DOI: 10.1097/00005344-199602000-00004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Cellular calcium modulates enzyme activity, cell proliferation, and differentiation. In vascular smooth muscle cells (VSMC), calcium may contribute to increased vascular contractility and structural alterations in both hypertension and atherosclerosis. We investigated the role of calcium in angiotensin II (AII)-induced prostaglandin release and DNA synthesis in VSMC. Prostaglandin levels were determined by radioimmunoassay, and DNA synthesis was determined by the incorporation of [3H]thymidine. AII dose-dependently stimulated the release of prostaglandin E2 and prostaglandin I2, and this effect was synergistically enhanced by the Ca2+ ionophore A23187. Conversely, the AII response was inhibited by EGTA, a chelator of Ca2+ ions and by verapamil and nifedipine, two Ca2+ channel blockers or by incubation of the cells without exogenous Ca2+. TMB-8, an inhibitor of calcium mobilization, also strongly reduced angiotensin response. Similar results were obtained for angiotensin III (AIII) and vasopressin, two other agonists of prostaglandin production. AII- or serum-stimulated DNA synthesis was almost abolished by EGTA, whereas TMB-8, verapamil, and nifedipine had little or no effect. The production of prostaglandins triggered by angiotensins and vasopressin in VSMC is dependent on both intracellular and extracellular calcium, with calcium entering through L-type Ca2+ channels. Extracellular calcium is important for AII and serum mitogenic activity, but L-type Ca2+ channels do not appear to be implicated.
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Affiliation(s)
- R M Catalioto
- Department of Pharmacology, Laboratori Guidotti SpA, Pisa
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Abstract
The orderly sequence of events that constitutes the cell cycle is carefully regulated. A part of this regulation depends upon the ubiquitous calcium signalling system. Many growth factors utilize the messenger inositol trisphosphate (InsP3) to set up prolonged calcium signals, often organized in an oscillatory pattern. These repetitive calcium spikes require both the entry of external calcium and its release from internal stores. One function of this calcium signal is to activate the immediate early genes responsible for inducing resting cells (G0) to re-enter the cell cycle. It may also promote the initiation of DNA synthesis at the G1/S transition. Finally, calcium contributes to the completion of the cell cycle by stimulating events at mitosis. The role of calcium in cell proliferation is highlighted by the increasing number of anticancer therapies and immunosuppressant drugs directed towards this calcium signalling pathway.
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Affiliation(s)
- M J Berridge
- Babraham Institute Laboratory of Molecular Signalling, Department of Zoology, Cambridge, UK
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Simons M, Ariyoshi H, Salzman EW, Rosenberg RD. c-myb affects intracellular calcium handling in vascular smooth muscle cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1995; 268:C856-68. [PMID: 7733234 DOI: 10.1152/ajpcell.1995.268.4.c856] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The protooncogene c-myb is responsible for elevating intracellular calcium concentration ([Ca2+]i) at the G1/S interface in vascular smooth muscle cells (VSMC). However, the molecular components of this pathway are undefined, and the biological effects of increased levels of divalent cation are unknown. We have demonstrated that growth-arrested c-myb-transfected VSMC, compared with wild type VSMC, exhibit a fourfold increased number of insulin-like growth factor I (IGF-I) receptors, increased amount of secreted IGF-I activity, and a twofold increased level of [Ca2+]. The c-myb transfected cells, compared with wild type cells, also possess a twofold increased rate of calcium influx and a twofold decreased rate of calcium efflux. The elevated calcium influx rate of transfected cells is decreased to that of wild type cells with IGF-I neutralizing antibody, whereas the decreased calcium efflux rate of transfected cells is increased to that of wild type cells with antisense c-myb oligonucleotides. Proliferating wild type VSMC exhibit an increased calcium influx rate in late G1, which is dependent on production of augmented amounts of IGF-I activity but not increased levels of IGF-I receptors. The wild type VSMC also show a decreased calcium efflux rate at the same point in the cell cycle, which is dependent on expression of c-myb. The treatment of wild type cells with antisense c-myb or IGF-I receptor oligonucleotides induces a late G1 block in cell proliferation, which can be overcome by exposure to the calcium ionophore, 4-bromo-A-27318, in amounts sufficient to raise [Ca2+]i to levels observed at the G1/S interface. We conclude that IGF-I/IGF-I receptors and c-myb are involved in control of [Ca2+]i at the G1/S interface by separately regulating the rates of calcium influx and efflux and that elevated levels of divalent cation are necessary for progression of VSMC into the S phase of the cell cycle.
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Affiliation(s)
- M Simons
- Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA
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Early transient suppression of c-myb mRNA levels and induction of differentiation in Friend erythroleukemia cells by the [Ca2+]i-increasing agents cyclopiazonic acid and thapsigargin. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37037-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Bennett AM, Williams GM. Calcium as a permissive factor but not an initiation factor in DNA synthesis induction in cultured rat hepatocytes by the peroxisome proliferator ciprofibrate. Biochem Pharmacol 1993; 46:2219-27. [PMID: 8274155 DOI: 10.1016/0006-2952(93)90612-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The non-genotoxic hepatocarcinogen and peroxisome proliferating agent, ciprofibrate, is a liver mitogen both in vivo and in cultured adult rat hepatocytes, but the mechanisms of its mitogenicity have not been elucidated. We previously observed that ciprofibrate rapidly increased hepatocyte free intracellular Ca2+ concentration ([Ca2+]i), suggesting that this effect may play a role in the initiation of DNA synthesis. In the present study, we have identified a relationship between Ca2+ and the stimulation of hepatocyte DNA synthesis by ciprofibrate. Exposure of cultured adult rat hepatocytes to ciprofibrate (200 microM) for 48 hr increased DNA synthesis by approximately 2-fold, and this response was attenuated in a Ca(2+)-deficient medium and by the Ca2+ channel blockers nicardipine and verapamil. To examine the relationship between the stimulation of hepatocyte DNA synthesis and increases in [Ca2+]i by ciprofibrate, the intracellular Ca2+ chelator 5,5'-dimethyl-1,2-bis(2-aminophenoxyethane)-N,N,N',N'-tetraacetic acid (dimethyl-BAPTA) was employed. Pretreatment of hepatocytes with dimethyl-BAPTA blocked ciprofibrate-induced [Ca2+]i increase, but did not block ciprofibrate-induced hepatocyte DNA synthesis. Dimethyl-BAPTA was only effective in reducing ciprofibrate-induced DNA synthesis when present during the latter 24 hr of a 48-hr culture period. These data suggest that the early mobilization of hepatocyte [Ca2+]i by ciprofibrate does not play an initiating role in the induction of hepatocyte DNA synthesis but rather may operate as a permissive factor for the entry of ciprofibrate-treated adult rat hepatocytes into S-phase.
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Affiliation(s)
- A M Bennett
- Department of Experimental Pathology, New York Medical College, Valhalla 10595
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