1
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Field CJ, Perez AM, Samet T, Ricles V, Iovine MK, Lowe-Krentz LJ. Involvement of transmembrane protein 184a during angiogenesis in zebrafish embryos. Front Physiol 2022; 13:845407. [PMID: 36117693 PMCID: PMC9478037 DOI: 10.3389/fphys.2022.845407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 08/09/2022] [Indexed: 11/13/2022] Open
Abstract
Angiogenesis, the outgrowth of new blood vessels from existing vasculature, is critical during development, tissue formation, and wound healing. In response to vascular endothelial growth factors (VEGFs), endothelial cells are activated to proliferate and move towards the signal, extending the vessel. These events are directed by VEGF-VEGF receptor (Vegfr2) signal transduction, which in turn is modulated by heparan sulfate proteoglycans (HSPGs). HSPGs are glycoproteins covalently attached to HS glycosaminoglycan chains. Transmembrane protein 184a (Tmem184a) has been recently identified as a heparin receptor, which is believed to bind heparan sulfate chains in vivo. Therefore, Tmem184a has the potential to fine-tune interactions between VEGF and HS, modulating Vegfr2-dependent angiogenesis. The function of Tmem184a has been investigated in the regenerating zebrafish caudal fin, but its role has yet to be evaluated during developmental angiogenesis. Here we provide insights into how Tmem184a contributes to the proper formation of the vasculature in zebrafish embryos. First, we find that knockdown of Tmem184a causes a reduction in the number of intact intersegmental vessels (ISVs) in the zebrafish embryo. This phenotype mimics that of vegfr2b knockout mutants, which have previously been shown to exhibit severe defects in ISV development. We then test the importance of HS interactions by removing the binding domain within the Tmem184a protein, which has a negative effect on angiogenesis. Tmem184a is found to act synergistically with Vegfr2b, indicating that the two gene products function in a common pathway to modulate angiogenesis. Moreover, we find that knockdown of Tmem184a leads to an increase in endothelial cell proliferation but a decrease in the amount of VE-cadherin present. Together, these findings suggest that Tmem184a is necessary for ISVs to organize into mature, complete vessels.
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2
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Dong C, Choi YK, Lee J, Zhang XF, Honerkamp-Smith A, Widmalm G, Lowe-Krentz LJ, Im W. Structure, Dynamics, and Interactions of GPI-Anchored Human Glypican-1 with Heparan Sulfates in a Membrane. Glycobiology 2020; 31:593-602. [PMID: 33021626 DOI: 10.1093/glycob/cwaa092] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 09/24/2020] [Accepted: 09/24/2020] [Indexed: 12/12/2022] Open
Abstract
Glypican-1 and its heparan sulfate (HS) chains play important roles in modulating many biological processes including growth factor signaling. Glypican-1 is bound to a membrane surface via a glycosylphosphatidylinositol (GPI)-anchor. In this study, we used all-atom molecular modeling and simulation to explore the structure, dynamics, and interactions of GPI-anchored glypican-1, three HS chains, membranes, and ions. The folded glypican-1 core structure is stable, but has substantial degrees of freedom in terms of movement and orientation with respect to the membrane due to the long unstructured C-terminal region linking the core to the GPI-anchor. With unique structural features depending on the extent of sulfation, high flexibility of HS chains can promote multi-site interactions with surrounding molecules near and above the membrane. This study is a first step toward all-atom molecular modeling and simulation of the glycocalyx, as well as its modulation of interactions between growth factors and their receptors.
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Affiliation(s)
- Chuqiao Dong
- Department of Mechanical Engineering and Mechanicss, Lehigh University, Bethlehem, PA, 18015, United States
| | - Yeol Kyo Choi
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, 18015, United States
| | - Jumin Lee
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, 18015, United States
| | - X Frank Zhang
- Department of Mechanical Engineering and Mechanicss, Lehigh University, Bethlehem, PA, 18015, United States.,Department of Bioengineering, Lehigh University, Bethlehem, PA, 18015, United States
| | | | - Göran Widmalm
- Department of Organic Chemistry, Stockholm University, S-106 91 Stockholm, Sweden
| | - Linda J Lowe-Krentz
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, 18015, United States
| | - Wonpil Im
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, 18015, United States.,Department of Bioengineering, Lehigh University, Bethlehem, PA, 18015, United States.,Department of Chemistry, Lehigh University, Bethlehem, PA, 18015, United States
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3
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Talotta-Altenburg LM, Ciabattoni GO, Laessig MA, Lowe-Krentz LJ. TMEM184A: Evidence for a Potential Link Between HSPGs and Mechanotransduction. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.07092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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4
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Li Y, Talotta-Altenburg LM, Silimperi KA, Ciabattoni GO, Lowe-Krentz LJ. Endothelial nitric oxide synthase activation is required for heparin receptor effects on vascular smooth muscle cells. Am J Physiol Cell Physiol 2019; 318:C463-C475. [PMID: 31891520 DOI: 10.1152/ajpcell.00284.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Published studies indicate that TMEM184A is a heparin receptor that interacts with and transduces stimulation from heparin in vascular cells. Previous studies have indicated that heparin increases endothelial nitric oxide synthase (eNOS) activity in bovine endothelial cells. However, the precise mechanism remains unknown. In this study, we investigated the impact of heparin treatment and TMEM184A on eNOS's activation and the role of eNOS in heparin signaling in the cloned A7r5 rat vascular smooth muscle cell line and confirmed results in endothelial cells. We employed a combination of TMEM184A knockdown A7r5 cells along with transient eNOS knockdown and enzyme inhibitor strategies. The results indicate that heparin induces phosphorylation of eNOS. eNOS can be immunoprecipitated with TMEM184A and is internalized to the perinuclear region in a TMEM184A-dependent manner in response to heparin. We also examined how heparin treatment leads to phosphorylation of eNOS and confirmed that TMEM184A and Ca2+ were required to mediate heparin-elicited eNOS phosphorylation. Evidence supporting the involvement of transient receptor potential cation channel subfamily V member 4 with TMEM184A in this eNOS activation process is also presented.
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Affiliation(s)
- Yaqiu Li
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania
| | | | - Kayli A Silimperi
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania
| | - Grace O Ciabattoni
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania
| | - Linda J Lowe-Krentz
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania
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5
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Farwell SLN, Reylander KG, Iovine MK, Lowe-Krentz LJ. Novel Heparin Receptor Transmembrane Protein 184a Regulates Angiogenesis in the Adult Zebrafish Caudal Fin. Front Physiol 2017; 8:671. [PMID: 28936181 PMCID: PMC5594097 DOI: 10.3389/fphys.2017.00671] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 08/23/2017] [Indexed: 12/22/2022] Open
Abstract
Transmembrane protein 184A (TMEM184A) was recently identified as the heparin receptor in vascular cells. Heparin binds specifically to TMEM184A and induces anti-proliferative signaling in vitro. Though it is highly conserved, the physiological function of TMEM184A remains unknown. The objective of this study was to investigate the expression and effects on vascular regeneration of TMEM184A using the adult zebrafish regenerating caudal fin as an in vivo model. Here, we show that Tmem184a is expressed in vascular endothelial cells (ECs) of mature and regenerating zebrafish fins. Transient morpholino (MO)-mediated knockdown of Tmem184a using two validated MOs results in tangled regenerating vessels that do not grow outward and limit normal overall fin regeneration. A significant increase in EC proliferation is observed. Consistent with in vitro work with tissue culture vascular cells, heparin has the opposite effect and decreases EC proliferation which also hinders overall fin regeneration. Collectively, our study suggests that Tmem184a is a novel regulator of angiogenesis.
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Affiliation(s)
- Sara Lynn N Farwell
- Department of Biological Sciences, Lehigh UniversityBethlehem, PA, United States
| | - Kimberly G Reylander
- Department of Biological Sciences, Lehigh UniversityBethlehem, PA, United States
| | - M Kathryn Iovine
- Department of Biological Sciences, Lehigh UniversityBethlehem, PA, United States
| | - Linda J Lowe-Krentz
- Department of Biological Sciences, Lehigh UniversityBethlehem, PA, United States
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6
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Abstract
When novel proteins are identified through affinity-based isolation and bioinformatics analysis, they are often largely uncharacterized. Antibodies against specific peptides within the predicted sequence allow some localization experiments. However, other possible interactions with the antibodies often cannot be excluded. This situation provided an opportunity to develop a set of assays dependent on the protein sequence. Specifically, a construct containing the gene sequence coupled to the GFP coding sequence at the C-terminal end of the protein was obtained and employed for these purposes. Experiments to characterize localization, ligand affinity, and gain of function were originally designed and carried out to confirm the identification of TMEM184A as a heparin receptor1. In addition, the construct can be employed for studies addressing membrane topology questions and detailed protein-ligand interactions. The present report presents a range of experimental protocols based on the GFP-TMEM184A construct expressed in vascular cells that could easily be adapted for other novel proteins.
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Affiliation(s)
| | | | - Yaqiu Li
- Department of Biological Sciences, Lehigh University
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7
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Farwell SLN, Kanyi D, Hamel M, Slee JB, Miller EA, Cipolle MD, Lowe-Krentz LJ. Heparin Decreases in Tumor Necrosis Factor α (TNFα)-induced Endothelial Stress Responses Require Transmembrane Protein 184A and Induction of Dual Specificity Phosphatase 1. J Biol Chem 2016; 291:5342-54. [PMID: 26769965 DOI: 10.1074/jbc.m115.681288] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Indexed: 11/06/2022] Open
Abstract
Despite the large number of heparin and heparan sulfate binding proteins, the molecular mechanism(s) by which heparin alters vascular cell physiology is not well understood. Studies with vascular smooth muscle cells (VSMCs) indicate a role for induction of dual specificity phosphatase 1 (DUSP1) that decreases ERK activity and results in decreased cell proliferation, which depends on specific heparin binding. The hypothesis that unfractionated heparin functions to decrease inflammatory signal transduction in endothelial cells (ECs) through heparin-induced expression of DUSP1 was tested. In addition, the expectation that the heparin response includes a decrease in cytokine-induced cytoskeletal changes was examined. Heparin pretreatment of ECs resulted in decreased TNFα-induced JNK and p38 activity and downstream target phosphorylation, as identified through Western blotting and immunofluorescence microscopy. Through knockdown strategies, the importance of heparin-induced DUSP1 expression in these effects was confirmed. Quantitative fluorescence microscopy indicated that heparin treatment of ECs reduced TNFα-induced increases in stress fibers. Monoclonal antibodies that mimic heparin-induced changes in VSMCs were employed to support the hypothesis that heparin was functioning through interactions with a receptor. Knockdown of transmembrane protein 184A (TMEM184A) confirmed its involvement in heparin-induced signaling as seen in VSMCs. Therefore, TMEM184A functions as a heparin receptor and mediates anti-inflammatory responses of ECs involving decreased JNK and p38 activity.
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Affiliation(s)
- Sara Lynn N Farwell
- From the Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015
| | - Daniela Kanyi
- From the Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, the Department of Chemistry, Lehigh University, Allentown, Pennsylvania 18103
| | - Marianne Hamel
- From the Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015
| | - Joshua B Slee
- From the Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, the Department of Natural Sciences, DeSales University, Center Valley, Pennsylvania 18034
| | - Elizabeth A Miller
- From the Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015
| | - Mark D Cipolle
- the Department of Surgery, Lehigh Valley Hospital Center, Allentown, Pennsylvania 18103, and
| | - Linda J Lowe-Krentz
- From the Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015,
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8
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Pugh RJ, Slee JB, Farwell SLN, Li Y, Barthol T, Patton WA, Lowe-Krentz LJ. Transmembrane Protein 184A Is a Receptor Required for Vascular Smooth Muscle Cell Responses to Heparin. J Biol Chem 2016; 291:5326-41. [PMID: 26769966 DOI: 10.1074/jbc.m115.681122] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Indexed: 11/06/2022] Open
Abstract
Vascular cell responses to exogenous heparin have been documented to include decreased vascular smooth muscle cell proliferation following decreased ERK pathway signaling. However, the molecular mechanism(s) by which heparin interacts with cells to induce those responses has remained unclear. Previously characterized monoclonal antibodies that block heparin binding to vascular cells have been found to mimic heparin effects. In this study, those antibodies were employed to isolate a heparin binding protein. MALDI mass spectrometry data provide evidence that the protein isolated is transmembrane protein 184A (TMEM184A). Commercial antibodies against three separate regions of the TMEM184A human protein were used to identify the TMEM184A protein in vascular smooth muscle cells and endothelial cells. A GFP-TMEM184A construct was employed to determine colocalization with heparin after endocytosis. Knockdown of TMEM184A eliminated the physiological responses to heparin, including effects on ERK pathway activity and BrdU incorporation. Isolated GFP-TMEM184A binds heparin, and overexpression results in additional heparin uptake. Together, these data support the identification of TMEM184A as a heparin receptor in vascular cells.
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Affiliation(s)
- Raymond J Pugh
- Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015
| | - Joshua B Slee
- From the Departments of Biological Sciences and the Department of Natural Sciences, DeSales University, Center Valley, Pennsylvania 18034
| | | | - Yaqiu Li
- From the Departments of Biological Sciences and
| | | | - Walter A Patton
- the Department of Chemistry, Lebanon Valley College, Annville, Pennsylvania 17003, and
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9
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Farwell SLN, Barthol T, Slee JB, Lowe-Krentz LJ. Abstract 645: Heparin’s Effects on Vascular Cells Require Transmembrane Receptor 184A. Arterioscler Thromb Vasc Biol 2015. [DOI: 10.1161/atvb.35.suppl_1.645] [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: 11/16/2022]
Abstract
Introduction:
Though heparin has been used in the clinic for decades, molecular mechanism(s) underlying heparin’s functions independent of anti-coagulation are still unclear. Transmembrane protein 184A (TMEM184A) is conserved, yet its physiological and molecular functions remain unknown. There are few studies reporting its expression and potential role in membrane trafficking in exocrine cells, and involvement in signaling during male germ cell differentiation. Sequence analysis reveals that the C terminal domain includes a putative binding site for heparin. We have previously shown that heparin decreases proliferation in vascular smooth muscle cells (VSMCs) by inducing expression of MKP-1 that decreases Elk-1 and ERK activation.
Hypothesis:
We hypothesized that TMEM184A plays a role in mediating heparin effects in vascular cells.
Methods and Results:
We observed TMEM184A expression in vascular cells through immunofluorescence and western blotting using three primary antibodies against different regions in TMEM184A, and visualized cells with confocal microscopy. To investigate whether heparin effects were dependent on TMEM184A, VSMCs were electroporated with 20 μg/ml control or TMEM184A shRNA. Control and knockdown VSMCs were treated with 200 μg/ml heparin for 20 min followed by 2 μg/ml platelet-derived growth factor (PDGF). Activated ERK or Elk-1 in the nucleus was compared to untreated controls or cells treated with PDGF alone. Quantitative immunofluorescence of over 100 cells for each treatment from at least three independent experiments showed that heparin treatment prior to 20 min PDGF stimulation significantly decreased active ERK by nearly 50% in control shRNA cells compared to cells treated with PDGF alone (20 min PDGF = 100.0% ± 3.76%, heparin pre-treatment = 55.5% ± 2.20%; p<0.001). In TMEM184A knockdown cells, heparin pre-treatment did not decrease ERK activation (20 min PDGF = 100.0% ± 3.27%, heparin pre-treatment = 109.8% ± 3.06%). Similar results were observed for Elk-1. Heparin also did not decrease proliferation in response to PDGF in knockdown VSMCs as shown with BrdU incorporation assays.
Conclusions:
Our results provide functional evidence that heparin signaling in VSMCs is mediated at least in part by TMEM184A.
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10
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Gilotti AC, Nimlamool W, Pugh R, Slee JB, Barthol TC, Miller EA, Lowe-Krentz LJ. Heparin responses in vascular smooth muscle cells involve cGMP-dependent protein kinase (PKG). J Cell Physiol 2014; 229:2142-52. [PMID: 24911927 DOI: 10.1002/jcp.24677] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Accepted: 05/20/2014] [Indexed: 11/08/2022]
Abstract
Published data provide strong evidence that heparin treatment of proliferating vascular smooth muscle cells results in decreased signaling through the ERK pathway and decreases in cell proliferation. In addition, these changes have been shown to be mimicked by antibodies that block heparin binding to the cell surface. Here, we provide evidence that the activity of protein kinase G is required for these heparin effects. Specifically, a chemical inhibitor of protein kinase G, Rp-8-pCPT-cGMS, eliminates heparin and anti-heparin receptor antibody effects on bromodeoxyuridine incorporation into growth factor-stimulated cells. In addition, protein kinase G inhibitors decrease heparin effects on ERK activity, phosphorylation of the transcription factor Elk-1, and heparin-induced MKP-1 synthesis. Although transient, the levels of cGMP increase in heparin treated cells. Finally, knock down of protein kinase G also significantly decreases heparin effects in growth factor-activated vascular smooth muscle cells. Together, these data indicate that heparin effects on vascular smooth muscle cell proliferation depend, at least in part, on signaling through protein kinase G.
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Affiliation(s)
- Albert C Gilotti
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania
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11
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Slee JB, Lowe-Krentz LJ. Actin realignment and cofilin regulation are essential for barrier integrity during shear stress. J Cell Biochem 2013; 114:782-95. [PMID: 23060131 DOI: 10.1002/jcb.24416] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 10/01/2012] [Indexed: 12/12/2022]
Abstract
Vascular endothelial cells and their actin microfilaments align in the direction of fluid shear stress (FSS) in vitro and in vivo. To determine whether cofilin, an actin severing protein, is required in this process, the levels of phospho-cofilin (serine-3) were evaluated in cells exposed to FSS. Phospho-cofilin levels decreased in the cytoplasm and increased in the nucleus during FSS exposure. This was accompanied by increased nuclear staining for activated LIMK, a cofilin kinase. Blocking stress kinases JNK and p38, known to play roles in actin realignment during FSS, decreased cofilin phosphorylation under static conditions, and JNK inhibition also resulted in decreased phospho-cofilin during FSS exposure. Inhibition of dynamic changes in cofilin phosphorylation through cofilin mutants decreased correct actin realignment. The mutants also decreased barrier integrity as did inhibition of the stress kinases. These results identify the importance of cofilin in the process of actin alignment and the requirement for actin realignment in endothelial barrier integrity during FSS.
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Affiliation(s)
- Joshua B Slee
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA
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12
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Nimlamool W, Bean BS, Lowe-Krentz LJ. Human sperm CRISP2 is released from the acrosome during the acrosome reaction and re-associates at the equatorial segment. Mol Reprod Dev 2013; 80:488-502. [DOI: 10.1002/mrd.22189] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 05/02/2013] [Indexed: 12/30/2022]
Affiliation(s)
- Wutigri Nimlamool
- Department of Biological Sciences; Lehigh University; Bethlehem Pennsylvania
| | - Barry S. Bean
- Department of Biological Sciences; Lehigh University; Bethlehem Pennsylvania
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13
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Phopin K, Nimlamool W, Lowe-Krentz LJ, Douglass EW, Taroni JN, Bean BS. Roles of mouse sperm-associated alpha-L-fucosidases in fertilization. Mol Reprod Dev 2013; 80:273-85. [DOI: 10.1002/mrd.22164] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 02/05/2013] [Indexed: 01/26/2023]
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14
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Blaukovitch CI, Pugh R, Gilotti AC, Kanyi D, Lowe-Krentz LJ. Heparin treatment of vascular smooth muscle cells results in the synthesis of the dual-specificity phosphatase MKP-1. J Cell Biochem 2010; 110:382-91. [PMID: 20235148 DOI: 10.1002/jcb.22543] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [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: 01/02/2023]
Abstract
The ability of heparin to block proliferation of vascular smooth muscle cells has been well documented. It is clear that heparin treatment can decrease the level of ERK activity in vascular smooth muscle cells that are sensitive to heparin. In this study, the mechanism by which heparin induces decreases in ERK activity was investigated by evaluating the dual specificity phosphatase, MKP-1, in heparin treated cells. Heparin induced MKP-1 synthesis in a time and concentration dependent manner. The time-course of MKP-1 expression correlated with the decrease in ERK activity. Over the same time frame, heparin treatment did not result in decreases in MEK-1 activity which could have, along with constitutive phosphatase activity, accounted for the decrease in ERK activity. Antibodies against a heparin receptor also induced the synthesis of MKP-1 along with decreasing ERK activity. Blocking either phosphatase activity or synthesis also blocked heparin-induced decreases in ERK activity. Consistent with a role for MKP-1, a nuclear phosphatase, heparin treated cells exhibited decreases in nuclear ERK activity more rapidly than cells not treated with heparin. The data support MKP-1 as a heparin-induced phosphatase that dephosphorylates ERK, decreasing ERK activity, in vascular smooth muscle cells.
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MESH Headings
- Animals
- Antibodies/immunology
- Blotting, Western
- Cells, Cultured
- Dual Specificity Phosphatase 1/biosynthesis
- Dual Specificity Phosphatase 1/metabolism
- Enzyme Activation
- Heparin/pharmacology
- Microscopy, Fluorescence
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Receptors, Cell Surface/immunology
- Swine
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15
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Vassallo JD, Janovitz EB, Wescott DM, Chadwick C, Lowe-Krentz LJ, Lehman-McKeeman LD. Biomarkers of Drug-Induced Skeletal Muscle Injury in the Rat: Troponin I and Myoglobin. Toxicol Sci 2009; 111:402-12. [DOI: 10.1093/toxsci/kfp166] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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Savage JM, Gilotti AC, Granzow CA, Molina F, Lowe-Krentz LJ. Antibodies against a putative heparin receptor slow cell proliferation and decrease MAPK activation in vascular smooth muscle cells. J Cell Physiol 2001; 187:283-93. [PMID: 11319752 DOI: 10.1002/jcp.1076] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [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: 11/12/2022]
Abstract
Heparin has long been known to slow the growth of vascular smooth muscle cells. However, the mechanism(s) by which heparin acts has yet to be resolved. The identification of a putative heparin receptor in endothelial cells with antibodies that blocked heparin binding to the cells provided the means to further examine the possible involvement of a heparin receptor in smooth muscle cell responses to heparin. Immunoprecipitation of a smooth muscle cell protein with the anti-heparin receptor antibodies provided evidence that the protein was present in smooth muscle cells. Experiments with the anti-heparin receptor antibodies indicate that the antibodies can mimic heparin in decreasing PDGF induced thymidine and BrdU incorporation. The anti-heparin receptor antibodies were also found to decrease MAPK activity levels after activation similarly to heparin. These results support the identification of a heparin receptor and its role in heparin effects on vascular smooth muscle cell growth.
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Affiliation(s)
- J M Savage
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015, USA
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17
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Abstract
Heparin is a natural anticoagulant molecule that can alter the activity and/or levels of other molecules involved in blood coagulation. Protein S, an anticoagulant protein, is synthesized and released into the plasma by endothelial cells. Immunological assays revealed a significant increase in protein S found in the media and in the endothelial cells after heparin treatment. Time assays revealed a rapid heparin effect on protein S levels in the media. Upon treatment with chondroitin sulfate, a small increase in the amount of protein S in the conditioned medium was also detected but the change in the cell-associated protein S levels after chondroitin sulfate treatment was a decrease rather than the increase implying that heparin and chondroitin sulfate are operating through different mechanisms. Radioimmunoprecipitations and cycloheximide treatments indicated no significant difference in protein S synthesis in heparin treated cells. In experiments comparing heparin and ammonium chloride effects, heparin seems to mimic the ammonium chloride effect on the levels of protein S in the media. Together, the data indicate that heparin increases the levels of protein S found in the media of cultured endothelial cells by producing a specific block in protein S degradation.
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Affiliation(s)
- C S Dougherty
- Department of Biological Sciences, Lehigh University, Bethlehem, Pa. 18015, USA
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18
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Patton WA, Granzow CA, Getts LA, Thomas SC, Zotter LM, Gunzel KA, Lowe-Krentz LJ. Identification of a heparin-binding protein using monoclonal antibodies that block heparin binding to porcine aortic endothelial cells. Biochem J 1995; 311 ( Pt 2):461-9. [PMID: 7487882 PMCID: PMC1136022 DOI: 10.1042/bj3110461] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [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: 01/25/2023]
Abstract
The binding of heparin or heparan sulphate to a variety of cell types results in specific changes in cell function. Endothelial cells treated with heparin alter their synthesis of heparan sulphate proteoglycans and extracellular matrix proteins. In order to identify a putative endothelial cell heparin receptor that could be involved in heparin signalling, anti-(endothelial cell) monoclonal antibodies that significantly inhibit heparin binding to endothelial cells were prepared. Four of these antibodies were employed in affinity-chromatographic isolation of a heparin-binding protein from detergent-solubilized endothelial cells. The heparin-binding protein isolated from porcine aortic endothelial cells using four different monoclonal antibodies has an M(r) of 45,000 assessed by SDS/PAGE. The 45,000-M(r) heparin-binding polypeptide is isolated as a multimer. The antibody-isolated protein binds to heparin-affinity columns as does the pure 45,000-M(r) polypeptide, consistent with its identification as a putative endothelial heparin receptor.
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MESH Headings
- Animals
- Antibodies, Monoclonal/pharmacology
- Aorta, Thoracic
- Cells, Cultured
- Chromatography, Affinity
- Chromatography, Gel
- Electrophoresis, Polyacrylamide Gel
- Endothelium, Vascular/cytology
- Endothelium, Vascular/immunology
- Endothelium, Vascular/metabolism
- Female
- Heparin/metabolism
- Hybridomas
- Mice
- Mice, Inbred BALB C
- Molecular Weight
- Protein Binding/drug effects
- Receptors, Cell Surface/analysis
- Receptors, Cell Surface/isolation & purification
- Receptors, Cell Surface/metabolism
- Swine
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Affiliation(s)
- W A Patton
- Department of Chemistry, Lehigh University, Bethlehem, PA 18015, USA
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19
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Lowe-Krentz LJ, Thompson K, Patton WA. Heparin releasable and nonreleasable forms of heparan sulfate proteoglycan are found on the surfaces of cultured porcine aortic endothelial cells. Mol Cell Biochem 1992; 109:51-60. [PMID: 1614420 DOI: 10.1007/bf00230873] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [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: 12/27/2022]
Abstract
Evidence suggests that endothelial cell layer heparan sulfate proteoglycans include a variety of different sized molecules which most likely contain different protein cores. In the present report, approximately half of endothelial cell surface associated heparan sulfate proteoglycan is shown to be releasable with soluble heparin. The remaining cell surface heparan sulfate proteoglycan, as well as extracellular matrix heparan sulfate proteoglycan, cannot be removed from the cells with heparin. The heparin nonreleasable cell surface proteoglycan can be released by membrane disrupting agents and is able to intercalate into liposomes. When the heparin releasable and nonreleasable cell surface heparan sulfate proteoglycans are compared, differences in proteoglycan size are also evident. Furthermore, the intact heparin releasable heparan sulfate proteoglycan is closer in size to proteoglycans isolated from the extracellular matrix and from growth medium than to that which is heparin nonreleasable. These data indicate that cultured porcine aortic endothelial cells contain at least two distinct types of cell surface heparan sulfate proteoglycans, one of which appears to be associated with the cells through its glycosaminoglycan chains. The other (which is more tightly associated) is probably linked via a membrane intercalated protein core.
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Affiliation(s)
- L J Lowe-Krentz
- Department of Chemistry, Lehigh University, Bethlehem, PA 18015
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20
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Lowe-Krentz LJ, Joyce JG. Venous and aortic porcine endothelial cells cultured under standardized conditions synthesize heparan sulfate chains which differ in charge. Anal Biochem 1991; 193:155-63. [PMID: 1872461 DOI: 10.1016/0003-2697(91)90001-a] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [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]
Abstract
The identification of a specific required carbohydrate structure for the antithrombin III binding site on heparin suggests that there may be specific structures in glycosaminoglycan chains which are necessary for other vascular functions of these carbohydrates. Determining that such differences exist requires a mechanism to isolate heparan sulfates from endothelial cells of specific vascular beds. The present report indicates that cultured venous and aortic endothelial cells synthesize heparan sulfate chains differing in charge density. There are two important conclusions from this work. (i) Endothelial cells from different blood vessels (i.e., vena cava and thoracic aorta) synthesize heparan sulfates which differ in negative charge and sulfation pattern. Specifically, aortic endothelial heparan sulfates have a higher negative charge than venous heparan sulfates. Differences are also observed in the nitrous acid degradation products of the heparan sulfates. (ii) Endothelial cells in culture retain the ability to synthesize different heparan sulfates in vitro after months of subculture under defined conditions. These results indicate that it is feasible to characterize heparan sulfates using cultured endothelial cells from a variety of vascular beds.
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Affiliation(s)
- L J Lowe-Krentz
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015
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21
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Abstract
Heparin is known to bind to cultured endothelial cells. This report documents that addition of heparin to endothelial cells results in an alteration of the heparan sulfate proteoglycan synthetic pattern. Specifically, the addition of saturating amounts of heparin to confluent cultures of porcine aortic endothelial cells results in an increase in the amount of radiolabeled heparan sulfate proteoglycan secreted into the growth medium. The increase is apparent as early as 8 h after heparin administration. Although there is often a decrease in the amount of cell surface heparan sulfate proteoglycan produced, it is not sufficient to account for the increase in the secreted form. Of the other glycosaminoglycans tested, only dextran sulfate and commercial heparan sulfate induce changes in heparan sulfate proteoglycan synthesis and secretion. Chondroitin sulfate glycosaminoglycans do not elicit this synthetic change. These data indicate that endothelial cells can alter the synthesis of heparan sulfate proteoglycans in response to extracellular signals including heparin and related glycosaminoglycans.
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Affiliation(s)
- P Morrison
- Department of Chemistry, Center for Molecular Biosciences and Biotechnology, Bethlehem, Pennsylvania 18015
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22
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Abstract
Heparan sulfate proteoglycans have been isolated from Swiss mouse 3T3 cells by using two nondegradative techniques: extraction with 4 M guanidine or 2.5% 1-butanol. These proteoglycans were separated from copurifying chondroitin sulfate proteoglycans by using ion-exchange chromatography on DEAE-cellulose in the presence of 2 M urea. The purified heparan sulfate proteoglycans are substantially smaller, ca. Mr 20 000, than those isolated from these same cells with trypsin, ca. Mr 720 000 [Johnston, L.S., Keller, K. L., & Keller, J. M. (1979) Biochim. Biophys. Acta 583, 81-94]. However, all of the heparan sulfate proteoglycans extracted by these three methods contain similar glycosaminoglycan chains (Mr 7500) and are derived from the same pool of cell surface associated molecules. The trypsin-released heparan sulfate proteoglycan (ca. Mr 720 000) can be significantly reduced in size (ca. Mr 33 000) under strong denaturing conditions in the presence of the disulfide reducing agent dithiothreitol, which suggests that this form of the molecule is a disulfide-bonded aggregate. The heparan sulfate proteoglycan isolated from the medium also undergoes a significant size reduction in the presence of dithiothreitol, indicating that a similar aggregate is formed as part of the normal release of heparan sulfate proteoglycans into the medium. These results suggest that well-shielded disulfide bonds between individual heparan sulfate proteoglycan monomers may account for the large variation in sizes which has been reported for heparan sulfate proteoglycans isolated from a variety of cells and tissues with a variety of extraction procedures.
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23
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Lowe-Krentz LJ, Keller JM. Multiple heparan sulfate proteoglycans synthesized by a basement membrane producing murine embryonal carcinoma cell line. Biochemistry 1983; 22:4412-9. [PMID: 6226313 DOI: 10.1021/bi00288a011] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The murine embryonal carcinoma derived cell line M1536-B3 secretes the basement membrane components laminin and entactin and, when grown in bacteriological dishes, produces and adheres to sacs of basement membrane components. Heparan sulfate proteoglycans have been isolated from these sacs, the cells, and the medium. At least three different heparan sulfate proteoglycans are produced by these cells as determined by proteoglycan size, glycosaminoglycan chain length, and charge density. The positions of the N- and O-sulfate groups in the glycosaminoglycan chains from each proteoglycan appear to be essentially the same despite differences in the size and culture compartment locations of the heparan sulfate proteoglycan. Additionally, small quantities of chondroitin sulfate proteoglycans are found in each fraction and copurify with each heparan sulfate proteoglycan. Because this cell line appears to synthesize at least three different heparan sulfate proteoglycans which are targeted to different final locations (basement membrane, cell surface, and medium), this will be a useful system in which to study the factors which determine final heparan sulfate proteoglycan structures and culture compartment targeting and the possible effects of the protein core(s) on heparan sulfate carbohydrate chain synthesis and secretion.
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