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Hashimoto H, Mandai S, Shikuma S, Kimura M, Toma H, Sakaguchi Y, Shiraishi S, Toshima N, Hoshino M, Kimura M, Ota J, Horiuchi S, Adachi S, Uchida S. The Effect of Antihypertensive Therapy on Skeletal Muscle Mass and Bone Mineral Density in Patients With End-Stage Kidney Disease. J Ren Nutr 2024; 34:223-234. [PMID: 37918643 DOI: 10.1053/j.jrn.2023.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 09/12/2023] [Accepted: 10/18/2023] [Indexed: 11/04/2023] Open
Abstract
OBJECTIVE Sarcopenia and osteoporosis substantially influence health and lifespan. However, the variables affecting skeletal muscle mass (SMM) or bone mineral density (BMD) remain unknown. DESIGN AND METHODS From August 1, 2018 to July 31, 2019, we conducted a single-center, observational cohort study with 291 Japanese adult patients on maintenance hemodialysis due to end-stage kidney disease, who had their femoral neck BMD measured using dual-energy X-ray absorptiometry. After 1-year follow-up, we measured annual changes of BMD (ΔBMD) and SMM (ΔSMM), which were calculated through a modified creatinine index (mg/kg/day) using age, sex, serum creatinine, and single-pooled Kt/V for urea. The factors associated with ΔSMM/ΔBMD or progressive loss of SMM/BMD, defined as ΔSMM/ΔBMD < 0 per year, respectively, were analyzed with multivariable, linear regression or logistic regression models. RESULTS The median age of the patients was 66 years and 33% were female. Dialysis vintage and β-blocker-use were inversely correlated to ΔSMM. In comparison to nonusers, β-blockers users had 2.5-fold higher SMM loss odd ratios [95% confidence interval, 1.3-4.8]. The risk for SMM loss caused by β-blockers was not increased in users of renin-angiotensin system inhibitors. The ΔBMD was negatively correlated to the usage of calcium channel blockers. The risk of developing osteosarcopenia, which was defined as annual loss of both SMM and BMD, increased in calcium channel blockers users. CONCLUSIONS The use of β-blockers is associated with an elevated risk of developing sarcopenia, whereas renin-angiotensin system inhibitors may minimize this effect in patients with end-stage kidney disease. Use of calcium channel blocker therapy was associated with a faster decline of BMD.
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Affiliation(s)
- Hiroko Hashimoto
- Department of Nephrology, Shuuwa General Hospital, Kasukabe, Saitama, Japan; Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
| | - Shintaro Mandai
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan.
| | - Satomi Shikuma
- Department of Nephrology, Shuuwa General Hospital, Kasukabe, Saitama, Japan
| | - Mai Kimura
- Department of Nephrology, Shuuwa General Hospital, Kasukabe, Saitama, Japan
| | - Hayato Toma
- Department of Nephrology, Shuuwa General Hospital, Kasukabe, Saitama, Japan
| | - Yuki Sakaguchi
- Department of Nephrology, Shuuwa General Hospital, Kasukabe, Saitama, Japan
| | - Sayuka Shiraishi
- Department of Nephrology, Shuuwa General Hospital, Kasukabe, Saitama, Japan
| | - Noriyuki Toshima
- Department of Nephrology, Shuuwa General Hospital, Kasukabe, Saitama, Japan
| | - Motoki Hoshino
- Department of Nephrology, Shuuwa General Hospital, Kasukabe, Saitama, Japan
| | - Moe Kimura
- Department of Nephrology, Shuuwa General Hospital, Kasukabe, Saitama, Japan
| | - Jun Ota
- Department of Nephrology, Shuuwa General Hospital, Kasukabe, Saitama, Japan
| | - Susumu Horiuchi
- Department of Urology, Shuuwa General Hospital, Kasukabe, Saitama, Japan
| | - Susumu Adachi
- Department of Cardiology, Shuuwa General Hospital, Kasukabe, Saitama, Japan
| | - Shinichi Uchida
- Department of Nephrology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo, Japan
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Golz AC, Bergemann C, Hildebrandt F, Emmert S, Nebe B, Rebl H. Selective adhesion inhibition and hyaluronan envelope reduction of dermal tumor cells by cold plasma-activated medium. Cell Adh Migr 2023; 17:1-19. [PMID: 37743639 PMCID: PMC10521339 DOI: 10.1080/19336918.2023.2260642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 06/06/2023] [Indexed: 09/26/2023] Open
Abstract
The sensitivity to cold plasma is specific to tumor cells while leaving normal tissue cells unaffected. This is the desired challenge in cancer therapy. Therefore, the focus of this work was a comparative study concerning the plasma sensitivity of dermal tumor cells (A-431) versus non-tumorigenic dermal cells (HaCaT) regarding their adhesion capacity. We found a selective inhibiting effect of plasma-activated medium on the adhesion of tumor cells while hardly affecting normal cells. We attributed this to a lower basal gene expression for the adhesion-relevant components CD44, hyaluronan synthase 2 (HAS2), HAS3, and the hyaluronidases in A431. Noteworthy, after plasma exposure, we revealed a significantly higher expression and synthesis of the hyaluronan envelope, the HAS3 gene, and the transmembrane adhesion receptors in non-tumorigenic HaCaTs.
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Affiliation(s)
- Anna-Christin Golz
- Department of Cell Biology, Rostock University Medical Center, Rostock, Germany
| | - Claudia Bergemann
- Department of Cell Biology, Rostock University Medical Center, Rostock, Germany
| | - Finja Hildebrandt
- Department of Cell Biology, Rostock University Medical Center, Rostock, Germany
| | - Steffen Emmert
- Clinic and Polyclinic for Dermatology and Venerology, Rostock University Medical Center, Rostock, Germany
| | - Barbara Nebe
- Department of Cell Biology, Rostock University Medical Center, Rostock, Germany
| | - Henrike Rebl
- Department of Cell Biology, Rostock University Medical Center, Rostock, Germany
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Liu Z, Wang Q, Zhang J, Qi S, Duan Y, Li C. The Mechanotransduction Signaling Pathways in the Regulation of Osteogenesis. Int J Mol Sci 2023; 24:14326. [PMID: 37762629 PMCID: PMC10532275 DOI: 10.3390/ijms241814326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 09/14/2023] [Accepted: 09/19/2023] [Indexed: 09/29/2023] Open
Abstract
Bones are constantly exposed to mechanical forces from both muscles and Earth's gravity to maintain bone homeostasis by stimulating bone formation. Mechanotransduction transforms external mechanical signals such as force, fluid flow shear, and gravity into intracellular responses to achieve force adaptation. However, the underlying molecular mechanisms on the conversion from mechanical signals into bone formation has not been completely defined yet. In the present review, we provide a comprehensive and systematic description of the mechanotransduction signaling pathways induced by mechanical stimuli during osteogenesis and address the different layers of interconnections between different signaling pathways. Further exploration of mechanotransduction would benefit patients with osteoporosis, including the aging population and postmenopausal women.
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Affiliation(s)
- Zhaoshuo Liu
- School of Engineering Medicine, Beihang University, Beijing 100191, China
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Qilin Wang
- School of Engineering Medicine, Beihang University, Beijing 100191, China
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Junyou Zhang
- School of Engineering Medicine, Beihang University, Beijing 100191, China
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Sihan Qi
- School of Engineering Medicine, Beihang University, Beijing 100191, China
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Yingying Duan
- School of Engineering Medicine, Beihang University, Beijing 100191, China
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Chunyan Li
- School of Engineering Medicine, Beihang University, Beijing 100191, China
- School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
- Key Laboratory of Big Data-Based Precision Medicine (Ministry of Industry and Information Technology), Beihang University, Beijing 100191, China
- Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beihang University, Beijing 100191, China
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4
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Primary human chondrocytes respond to compression with phosphoproteomic signatures that include microtubule activation. J Biomech 2019; 97:109367. [PMID: 31607375 DOI: 10.1016/j.jbiomech.2019.109367] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 09/14/2019] [Accepted: 09/22/2019] [Indexed: 12/20/2022]
Abstract
Chondrocytes are responsible for maintaining the cartilage that helps joints bear load and move smoothly. These cells typically respond to physiological compression with pathways consistent with matrix synthesis, and chondrocyte mechanotransduction is essential for homeostasis. In osteoarthritis (OA), chondrocyte mechanotransduction appears to be dysregulated, yet the mechanisms remain poorly understood. The objective of this study is to document the phosphoproteomic responses of primary osteoarthritic chondrocytes to physiological sinusoidal compression. We show that OA chondrocytes respond to physiological compression by first activating proteins consistent with cytoskeletal remodeling and decreased transcription, and then later activating proteins for transcription. These results show that several microtubule-related proteins respond to compression. Our results demonstrate that compression is a relevant physiological stimulus for osteoarthritic chondrocytes. Future analyses may build on these results to find differences in compression-induced phosphoproteins between normal and OA cells that lead to druggable targets to restore homeostasis to diseased joints.
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Fluid flow facilitates inward rectifier K + current by convectively restoring [K +] at the cell membrane surface. Sci Rep 2016; 6:39585. [PMID: 28004830 PMCID: PMC5177964 DOI: 10.1038/srep39585] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 11/24/2016] [Indexed: 01/25/2023] Open
Abstract
The inward rectifier Kir2.1 current (IKir2.1) was reported to be facilitated by fluid flow. However, the mechanism underlying this facilitation remains uncertain. We hypothesized that during K+ influx or efflux, [K+] adjacent to the outer mouth of the Kir2.1 channel might decrease or increase, respectively, compared with the average [K+] of the bulk extracellular solution, and that fluid flow could restore the original [K+] and result in the apparent facilitation of IKir2.1. We recorded the IKir2.1 in RBL-2H3 cells and HEK293T cells that were ectopically over-expressed with Kir2.1 channels by using the whole-cell patch-clamp technique. Fluid-flow application immediately increased the IKir2.1, which was not prevented by either the pretreatment with inhibitors of various protein kinases or the modulation of the cytoskeleton and caveolae. The magnitudes of the increases of IKir2.1 by fluid flow were driving force-dependent. Simulations performed using the Nernst-Planck mass equation indicated that [K+] near the membrane surface fell markedly below the average [K+] of the bulk extracellular solution during K+ influx, and, notably, that fluid flow restored the decreased [K+] at the cell surface in a flow rate-dependent manner. These results support the “convection-regulation hypothesis” and define a novel interpretation of fluid flow-induced modulation of ion channels.
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Marques R, Peres CG, Vaz CV, Gomes IM, Figueira MI, Cairrão E, Verde I, Maia CJ, Socorro S. 5α-Dihydrotestosterone regulates the expression of L-type calcium channels and calcium-binding protein regucalcin in human breast cancer cells with suppression of cell growth. Med Oncol 2015; 32:228. [PMID: 26255063 DOI: 10.1007/s12032-015-0676-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 08/03/2015] [Indexed: 12/20/2022]
Abstract
Androgens have been associated with the development of normal breast, and their role in mammary gland carcinogenesis has also been described. Several studies reported that androgens inhibit breast cancer cell growth, whereas others linked their action with the modulation of calcium (Ca(2+)) pumps, Ca(2+) channels and Ca(2+)-binding proteins. Also, it is known that deregulated Ca(2+) homeostasis has been implicated in the pathophysiology of breast. The L-type Ca(2+) channels (LTCCs) were found to be up-regulated in colon, colorectal and prostate cancer, but their presence in breast tissues remains uncharacterized. On the other hand, regucalcin (RGN) is a Ca(2+)-binding protein involved in the control of mammary gland cell proliferation, which has been identified as an androgen target gene in distinct tissues except breast. This study aimed to confirm the expression and activity of LTCCs in human breast cancer cells and investigate the effect of androgens in regulating the expression of α1C subunit (Cav1.2) of LTCCs and Ca(2+)-binding protein RGN. PCR, Western blot, immunofluorescence and electrophysiological experiments demonstrated the expression and activity of Cav1.2 subunit in MCF-7 cells. The MCF-7 cells were treated with 1, 10 or 100 nM of 5α-dihydrotestosterone (DHT) for 24-72 h. The obtained results showed that 1 nM DHT up-regulated the expression of Cav1.2 subunit while diminishing RGN protein levels, which was underpinned by reduced cell viability. These findings first confirmed the presence of LTCCs in breast cancer cells and opened new perspectives for the development of therapeutic approaches targeting Ca(2+) signaling.
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Affiliation(s)
- Ricardo Marques
- Faculdade de Ciências da Saúde, CICS-UBI - Health Sciences Research Center, University of Beira Interior, Av. Infante D. Henrique, 6200-506, Covilhã, Portugal
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Zhang X, Li F, Guo L, Hei H, Tian L, Peng W, Cai H. Forskolin Regulates L-Type Calcium Channel through Interaction between Actinin 4 and β3 Subunit in Osteoblasts. PLoS One 2015; 10:e0124274. [PMID: 25902045 PMCID: PMC4406748 DOI: 10.1371/journal.pone.0124274] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 03/11/2015] [Indexed: 12/23/2022] Open
Abstract
Voltage-dependent L-type calcium channels that permit cellular calcium influx are essential in calcium-mediated modulation of cellular signaling. Although the regulation of voltage-dependent L-type calcium channels is linked to many factors including cAMP-dependent protein kinase A (PKA) activity and actin cytoskeleton, little is known about the detailed mechanisms underlying the regulation in osteoblasts. Our present study investigated the modulation of L-type calcium channel activities through the effects of forskolin on actin reorganization and on its functional interaction with actin binding protein actinin 4. The results showed that forskolin did not significantly affect the trafficking of pore forming α1c subunit and its interaction with actin binding protein actinin 4, whereas it significantly increased the expression of β3 subunit and its interaction with actinin 4 in osteoblast cells as assessed by co-immunoprecipitation, pull-down assay, and immunostaining. Further mapping showed that the ABD and EF domains of actinin 4 were interaction sites. This interaction is independent of PKA phosphorylation. Knockdown of actinin 4 significantly decreased the activities of L-type calcium channels. Our study revealed a new aspect of the mechanisms by which the forskolin activation of adenylyl cyclase - cAMP cascade regulates the L-type calcium channel in osteoblast cells, besides the PKA mediated phosphorylation of the channel subunits. These data provide insight into the important role of interconnection among adenylyl cyclase, cAMP, PKA, the actin cytoskeleton, and the channel proteins in the regulation of voltage-dependent L-type calcium channels in osteoblast cells.
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Affiliation(s)
- Xuemei Zhang
- Department of Pharmacology, School of Pharmacy, Fudan University, 826 Zhangheng Road, Pudong New District, Shanghai, 201203, China
- * E-mail: (XZ); (WP)
| | - Fangping Li
- Department of Pharmacy, Jing’an District Center Hospital of Shanghai (Huashan Hospital, Fudan University, Jing’an Branch), 259 Xikang Road, Shanghai, 200040, China
| | - Lin Guo
- Department of Pharmacology, School of Pharmacy, Fudan University, 826 Zhangheng Road, Pudong New District, Shanghai, 201203, China
| | - Hongya Hei
- Department of Pharmacology, School of Pharmacy, Fudan University, 826 Zhangheng Road, Pudong New District, Shanghai, 201203, China
| | - Lulu Tian
- Department of Pharmacology, School of Pharmacy, Fudan University, 826 Zhangheng Road, Pudong New District, Shanghai, 201203, China
| | - Wen Peng
- Department of Nephrology, Putuo Hospital, Shanghai University of Traditional Chinese Medicine,164 Lanxi Road, Shanghai, 200062, PR China
- * E-mail: (XZ); (WP)
| | - Hui Cai
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, GA, 30322, United States of America
- Renal Section, Atlanta Veteran Administration Medical Center, Decatur, GA, 30033, United States of America
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8
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Cui X, Gooch H, Groves NJ, Sah P, Burne TH, Eyles DW, McGrath JJ. Vitamin D and the brain: key questions for future research. J Steroid Biochem Mol Biol 2015; 148:305-9. [PMID: 25448739 DOI: 10.1016/j.jsbmb.2014.11.004] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 10/30/2014] [Accepted: 11/04/2014] [Indexed: 12/21/2022]
Abstract
Over the last decade a convergent body of evidence has emerged from epidemiology, animal experiments and clinical trials which links low vitamin D status with a range of adverse neuropsychiatric outcomes. This research demonstrates that the timing of exposure to low vitamin D influences the nature of brain phenotypes, as exposures during gestation versus adulthood result in different phenotypes. With respect to early life exposures, there is robust evidence from rodent experiments indicating that transient developmental vitamin D (DVD) deficiency is associated with changes in brain structure, neurochemistry, gene and protein expression and behavior. In particular, DVD deficiency is associated with alterations in the dopaminergic neurotransmitter systems. In contrast, recently published animal experiments indicate that adult vitamin D (AVD) deficiency is associated with more subtle neurochemical and behavioral phenotypes. This paper explores key issues that need to be addressed in future research. There is a need to define the timing and duration of the 'critical window' during which low vitamin D status is associated with differential and adverse brain outcomes. We discuss the role for 'two-hit hypotheses', which propose that adult vitamin D deficiency leaves the brain more vulnerable to secondary adverse exposures, and thus may exacerbate disease progression. Finally, we explore the evidence implicating a role for vitamin D in rapid, non-genomic mechanisms that may involve L-type calcium channels and brain function. This article is part of a Special Issue entitled '17th Vitamin D Workshop'.
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Affiliation(s)
- Xiaoying Cui
- Queensland Brain Institute, University of Queensland, Qld 4072, Australia.
| | - Helen Gooch
- Queensland Brain Institute, University of Queensland, Qld 4072, Australia
| | - Natalie J Groves
- Queensland Brain Institute, University of Queensland, Qld 4072, Australia
| | - Pankaj Sah
- Queensland Brain Institute, University of Queensland, Qld 4072, Australia
| | - Thomas H Burne
- Queensland Brain Institute, University of Queensland, Qld 4072, Australia; Queensland Centre for Mental Health Research, Wacol, Qld 4076, Australia
| | - Darryl W Eyles
- Queensland Brain Institute, University of Queensland, Qld 4072, Australia; Queensland Centre for Mental Health Research, Wacol, Qld 4076, Australia
| | - John J McGrath
- Queensland Brain Institute, University of Queensland, Qld 4072, Australia; Queensland Centre for Mental Health Research, Wacol, Qld 4076, Australia; Discipline of Psychiatry, University of Queensland, QLD 4072, Australia
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9
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Intracellular calcium dynamics dependent on defined microtopographical features of titanium. Biomaterials 2015; 46:48-57. [DOI: 10.1016/j.biomaterials.2014.12.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 12/10/2014] [Accepted: 12/16/2014] [Indexed: 02/06/2023]
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Davis TA, Loos B, Engelbrecht AM. AHNAK: the giant jack of all trades. Cell Signal 2014; 26:2683-93. [PMID: 25172424 DOI: 10.1016/j.cellsig.2014.08.017] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 08/08/2014] [Accepted: 08/18/2014] [Indexed: 12/19/2022]
Abstract
The nucleoprotein AHNAK is an unusual and somewhat mysterious scaffolding protein characterised by its large size of approximately 700 kDa. Several aspects of this protein remain uncertain, including its exact molecular function and regulation on both the gene and protein levels. Various studies have attempted to annotate AHNAK and, notably, protein interaction and expression analyses have contributed greatly to our current understanding of the protein. The implicated biological processes are, however, very diverse, ranging from a role in the formation of the blood-brain barrier, cell architecture and migration, to the regulation of cardiac calcium channels and muscle membrane repair. In addition, recent evidence suggests that AHNAK might be yet another accomplice in the development of tumour metastasis. This review will discuss the different functional roles of AHNAK, highlighting recent advancements that have added foundation to the proposed roles while identifying ties between them. Implications for related fields of research are noted and suggestions for future research that will assist in unravelling the function of AHNAK are offered.
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Affiliation(s)
- T A Davis
- Department of Physiological Sciences, University of Stellenbosch, Mike de Vries Building, c/o Merriman Avenue and Bosman Street, Stellenbosch 7600, South Africa.
| | - B Loos
- Department of Physiological Sciences, University of Stellenbosch, Mike de Vries Building, c/o Merriman Avenue and Bosman Street, Stellenbosch 7600, South Africa
| | - A-M Engelbrecht
- Department of Physiological Sciences, University of Stellenbosch, Mike de Vries Building, c/o Merriman Avenue and Bosman Street, Stellenbosch 7600, South Africa
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11
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Kodama D, Togari A. Store-operated calcium entry induced by activation of Gq-coupled alpha1B adrenergic receptor in human osteoblast. Biochem Biophys Res Commun 2013; 437:239-44. [PMID: 23806689 DOI: 10.1016/j.bbrc.2013.06.047] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 06/15/2013] [Indexed: 11/26/2022]
Abstract
Recent studies have revealed that the sympathetic nervous system is involved in bone metabolism. We previously reported that noradrenaline (NA) suppressed K(+) currents via Gi/o protein-coupled alpha1B-adrenergic receptor (α1B-AR) in human osteoblast SaM-1 cells. Additionally, it has been demonstrated that the intracellular Ca(2+) level ([Ca(2+)]i) was increased by NA via α1B-AR. In this study, we investigated the signal pathway of NA-induced [Ca(2+)]i elevation by using Ca(2+) fluorescence imaging in SaM-1 cells. NA-induced [Ca(2+)]i elevation was suppressed by pretreatment with a PLC inhibitor, U73122. This suggested that the [Ca(2+)]i elevation was mediated by Gq protein-coupled α1B-AR. On the other hand, NA-induced [Ca(2+)]i elevation was completely abolished in Ca(2+)-free solution, which suggested that Ca(2+) influx is the predominant pathway of NA-induced [Ca(2+)]i elevation. Although the inhibition of K(+) channel by NA caused membrane depolarization, the [Ca(2+)]i elevation was not affected by voltage-dependent Ca(2+) channel blockers, nifedipine and mibefradil. Meanwhile, NA-induced [Ca(2+)]i elevation was abolished following activation of store-operated Ca(2+) channel by thapsigargin. Additionally, the [Ca(2+)]i elevation was suppressed by store-operated channel inhibitors, 2-APB, flufenamate, GdCl3 and LaCl3. These results suggest that Ca(2+) influx through store-operated Ca(2+) channels plays a critical role in the signal transduction pathway of Gq protein-coupled α1B-AR in human osteoblasts.
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Affiliation(s)
- Daisuke Kodama
- Department of Pharmacology, School of Dentistry, Aichi-Gakuin University, 1-100 Kusumoto-cho, Chikusa-ku, Nagoya 464-8650, Japan.
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12
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Abstract
Micro- and nanotopography as well as the surface chemistry of biomaterials affect cell adhesion, proliferation and cell differentiation. Furthermore, the organization and localization of intracellular adhesion components such as the actin cytoskeleton are also altered dependent on the material surface topography. However, the detailed influence of the material micro-structure on cellular mechanisms on the molecular level is still unknown. This study is intended to elucidate such effects using regular pillar structures to characterize the modulation of cell responses like the regulation of voltage-sensitive calcium channels as well as signaling molecules in human osteoblasts. To analyze cell behavior on defined biomaterial surfaces, human osteoblastic MG 63 cells were cultured on geometrically micro textured titanium coated silicon wafers, as opposed to planar titanium references. Samples were fabricated by a photolithographic process using the negative tone resist SU 8 and sputter-coated with 100 nm titanium. Immunofluorescence staining and flow cytometry are used to detect the expression levels and the function of T type calcium channels. Knowledge about the biocomplexity of cell behavior dependent on topographical characteristics is of clinical relevance for the development of implant designs in tissue engineering.
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