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Bae S, Yoon YG, Kim JY, Park IC, An S, Lee JH, Bae S. Melatonin increases growth properties in human dermal papilla spheroids by activating AKT/GSK3β/β-Catenin signaling pathway. PeerJ 2022; 10:e13461. [PMID: 35607451 PMCID: PMC9123888 DOI: 10.7717/peerj.13461] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 04/28/2022] [Indexed: 01/14/2023] Open
Abstract
Background Melatonin, a neurohormone, maybe involved in physiological processes, such as antioxidation, anti-inflammation, and hair growth. In the present study, we investigated the effects of melatonin on proliferation and intracellular signaling in DP cells using a three-dimensional (3D) spheroid culture system that mimics the in vivo hair follicle system. Methods DP cells were incubated in monolayer (2D) and 3D spheroid culture systems. The expression levels of melatonin receptors in DP cells were analyzed using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blotting. The effect of melatonin on the hair-inductive property of DP cells was analyzed using a WST-1-based proliferation assay, determination of DP spheroid size, expression analysis of DP signature genes, and determination of β-catenin stabilization in DP cells. The AKT/GSK3β/β-catenin signaling pathway associated with melatonin-induced β-catenin stabilization in DP cells was investigated by analyzing changes in upstream regulator proteins, including AKT, GSK3β, and their phosphorylated forms. Results The expression levels of the melatonin receptors were higher in human DP cells than in human epidermal keratinocytes and human dermal fibroblast cells. Comparing the expression level according to the human DP cell culture condition, melatonin receptor expression was upregulated in the 3D culture system compared to the traditional two-dimensional monolayer culture system. Cell viability analysis showed that melatonin concentrations up to 1 mM did not affect cell viability. Moreover, melatonin increased the diameter of DP cell 3D spheroids in a dose-dependent manner. Immunoblotting and qRT-PCR analysis revealed that melatonin upregulated the expression of hair growth-related genes, including alkaline phosphatase, bone morphogenetic protein 2, versican, and wingless-int 5A, in a melatonin receptor-dependent manner. Cell fractionation analysis showed that melatonin increased the nuclear localization of β-catenin. This result correlated with the increased transcriptional activation of T-cell factor/lymphoid enhancer factor-responsive luciferase induced by melatonin treatment. Interestingly, melatonin induced the phosphorylation of protein kinase B/AKT at serine 473 residue and GSK-3β at serine 9 residue. To determine whether AKT phosphorylation at serine 473 induced β-catenin nuclear translocation through GSK3β phosphorylation at serine 9, the PI3K/AKT inhibitor LY294002 was cotreated with melatonin. Immunoblotting showed that LY294002 inhibited melatonin-induced phosphorylation of GSK3β at serine 9 residue and β-catenin activation. Conclusion Collectively, this report suggests that melatonin promotes growth properties by activating the AKT/GSK3β/β-catenin signaling pathway through melatonin receptors.
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Affiliation(s)
- Sowon Bae
- Research Institute for Molecular-Targeted Drugs, Department of Cosmetics Engineering, Konkuk University, Seoul, Republic of Korea
| | - Yoo Gyeong Yoon
- Research Institute for Molecular-Targeted Drugs, Department of Cosmetics Engineering, Konkuk University, Seoul, Republic of Korea,R&D Planning Dept., Dermalab Co., Ltd, Suwon-si, Gyeonggi-do, Republic of Korea
| | - Ji Yea Kim
- Division of Fusion Radiology Research, Korea Institute of Radiological & Medical Sciences, Seoul, Republic of Korea
| | - In-Chul Park
- Division of Fusion Radiology Research, Korea Institute of Radiological & Medical Sciences, Seoul, Republic of Korea
| | - Sungkwan An
- Research Institute for Molecular-Targeted Drugs, Department of Cosmetics Engineering, Konkuk University, Seoul, Republic of Korea
| | - Jae Ho Lee
- Research Institute for Molecular-Targeted Drugs, Department of Cosmetics Engineering, Konkuk University, Seoul, Republic of Korea
| | - Seunghee Bae
- Research Institute for Molecular-Targeted Drugs, Department of Cosmetics Engineering, Konkuk University, Seoul, Republic of Korea
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Amstrup AK, Sikjaer T, Heickendorff L, Mosekilde L, Rejnmark L. Melatonin improves bone mineral density at the femoral neck in postmenopausal women with osteopenia: a randomized controlled trial. J Pineal Res 2015; 59:221-9. [PMID: 26036434 DOI: 10.1111/jpi.12252] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 05/29/2015] [Indexed: 01/11/2023]
Abstract
Melatonin is known for its regulation of circadian rhythm. Recently, studies have shown that melatonin may have a positive effect on the skeleton. By increasing age, the melatonin levels decrease, which may lead to a further imbalanced bone remodeling. We aimed to investigate whether treatment with melatonin could improve bone mass and integrity in humans. In a double-blind RCT, we randomized 81 postmenopausal osteopenic women to 1-yr nightly treatment with melatonin 1 mg (N = 20), 3 mg (N = 20), or placebo (N = 41). At baseline and after 1-yr treatment, we measured bone mineral density (BMD) by dual X-ray absorptiometry, quantitative computed tomography (QCT), and high-resolution peripheral QCT (HR-pQCT) and determined calciotropic hormones and bone markers. Mean age of the study subjects was 63 (range 56-73) yr. Compared to placebo, femoral neck BMD increased by 1.4% in response to melatonin (P < 0.05) in a dose-dependent manner (P < 0.01), as BMD increased by 0.5% in the 1 mg/day group (P = 0.55) and by 2.3% (P < 0.01) in the 3 mg/day group. In the melatonin group, trabecular thickness in tibia increased by 2.2% (P = 0.04), and volumetric bone mineral density (vBMD) in the spine, by 3.6% (P = 0.04) in the 3 mg/day. Treatment did not significantly affect BMD at other sites or levels of bone turnover markers; however, 24-hr urinary calcium was decreased in response to melatonin by 12.2% (P = 0.02). In conclusion, 1-yr treatment with melatonin increased BMD at femoral neck in a dose-dependent manner, while high-dose melatonin increased vBMD in the spine. Further studies are needed to assess the mechanisms of action and whether the positive effect of nighttime melatonin will protect against fractures.
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Affiliation(s)
- Anne Kristine Amstrup
- Department of Endocrinology and Internal Medicine (MEA), Aarhus University Hospital, THG, Aarhus, Denmark
| | - Tanja Sikjaer
- Department of Endocrinology and Internal Medicine (MEA), Aarhus University Hospital, THG, Aarhus, Denmark
| | - Lene Heickendorff
- Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark
| | - Leif Mosekilde
- Department of Endocrinology and Internal Medicine (MEA), Aarhus University Hospital, THG, Aarhus, Denmark
| | - Lars Rejnmark
- Department of Endocrinology and Internal Medicine (MEA), Aarhus University Hospital, THG, Aarhus, Denmark
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Domingue JC, Ao M, Sarathy J, George A, Alrefai WA, Nelson DJ, Rao MC. HEK-293 cells expressing the cystic fibrosis transmembrane conductance regulator (CFTR): a model for studying regulation of Cl- transport. Physiol Rep 2014; 2:2/9/e12158. [PMID: 25263207 PMCID: PMC4270233 DOI: 10.14814/phy2.12158] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The Human Embryonic Kidney 293 cell line (HEK‐293) readily lends itself to genetic manipulation and is a common tool for biologists to overexpress proteins of interest and study their function and molecular regulation. Although these cells have some limitations, such as an inability to form resistive monolayers necessary for studying transepithelial ion transport, they are nevertheless valuable in studying individual epithelial ion transporters. We report the use of HEK‐293 cells to study the cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel. While HEK‐293 cells endogenously express mRNA for the Cl− channels, ClC‐2 and TMEM16A, they neither express CFTR mRNA nor protein. Therefore, we stably transfected HEK‐293 cells with EGFP‐CFTR (HEK‐CFTR) and demonstrated CFTR function by measuring forskolin‐stimulated iodide efflux. This efflux was inhibited by CFTRinh172, and the protein kinase A inhibitor H89, but not by Ca2+ chelation. In contrast to intestinal epithelia, forskolin stimulation does not increase surface CFTR expression and does not require intact microtubules in HEK‐CFTR. To investigate the role of an endogenous GαS‐coupled receptor, we examined the bile acid receptor, TGR5. Although HEK‐CFTR cells express TGR5, the potent TGR5 agonist lithocholic acid (LCA; 5–500 μmol/L) did not activate CFTR. Furthermore, forskolin, but not LCA, increased [cAMP]i in HEK‐CFTR suggesting that endogenous TGR5 may not be functionally linked to GαS. However, LCA did increase [Ca2+]i and interestingly, abolished forskolin‐stimulated iodide efflux. Thus, we propose that the stable HEK‐CFTR cell line is a useful model to study the multiple signaling pathways that regulate CFTR. In this study, we characterize a HEK‐293 cell line, stably transfected with EGFP‐CFTR (HEK‐CFTR). We examined its regulation by endogenously expressed signaling pathways, in particular the cAMP and the GαS‐coupled bile acid receptor, TGR5, signaling pathways.
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Affiliation(s)
- Jada C Domingue
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois
| | - Mei Ao
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois
| | - Jayashree Sarathy
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois Department of Biological Sciences, Benedictine University, Lisle, Illinois
| | - Alvin George
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois
| | - Waddah A Alrefai
- Department of Medicine, University of Illinois at Chicago, Chicago, Illinois Jesse Brown V.A. Medical Center, Chicago, Illinois
| | - Deborah J Nelson
- Department of Pharmacological and Physiological Sciences, The University of Chicago, Chicago, Illinois
| | - Mrinalini C Rao
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, Illinois Department of Medicine, University of Illinois at Chicago, Chicago, Illinois
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Chen L, He X, Zhang Y, Chen X, Lai X, Shao J, Shi Y, Zhou N. Melatonin receptor type 1 signals to extracellular signal-regulated kinase 1 and 2 via Gi and Gs dually coupled pathways in HEK-293 cells. Biochemistry 2014; 53:2827-39. [PMID: 24724723 DOI: 10.1021/bi500092e] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The pineal gland hormone melatonin exerts its regulatory roles in a variety of physiological and pathological responses through two G protein-coupled receptors, melatonin receptor type 1 (MT1) and melatonin receptor type 2 (MT2), which have been recognized as promising targets in the treatment of a number of human diseases and disorders. The MT1 receptor was identified nearly 20 years ago; however, the molecular mechanisms by which MT1-mediated signaling affects physiology remain to be further elucidated. In this study, using HEK293 cells stably expressing the human MT1 receptor, melatonin induced a concentration-dependent activation of extracellular signal-regulated kinase 1 and 2 (ERK1/2). The melatonin-mediated phosphorylation of ERK1/2 at later time points (≥5 min) was strongly suppressed by pretreatment with pertussis toxin, but only a slight, if any, inhibition of ERK1/2 activation at early time points (≤2 min) was detected. Further experiments demonstrated that the Gβγ subunit, phosphoinositide 3-kinase, and calcium-insensitive protein kinase C were involved in the MT1-mediated activation of ERK1/2 at later time points (≥5 min). Moreover, results derived from cAMP assays combined with a MT1 mutant indicated that the human MT1 receptor could also couple to Gs protein, stimulating intracellular cAMP formation, and that the MT1-induced activation of ERK1/2 at early time points (≤2 min) was mediated by the Gs/cAMP/PKA cascade. Our findings may provide new insights into the pharmacological effects and physiological functions modulated by the MT1-mediated activation of ERK1/2.
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Affiliation(s)
- Linjie Chen
- Institute of Biochemistry, College of Life Sciences, Zhejiang University , Hangzhou, Zhejiang 310058, China
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Esposito T, Rendina D, Aloia A, Formicola D, Magliocca S, De Filippo G, Muscariello R, Mossetti G, Gianfrancesco F, Strazzullo P. The melatonin receptor 1A (MTNR1A) gene is associated with recurrent and idiopathic calcium nephrolithiasis. Nephrol Dial Transplant 2011; 27:210-8. [PMID: 21652546 DOI: 10.1093/ndt/gfr216] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Experimental evidence indicate that melatonin regulates some renal tubular functions via specific melatonin receptors (MTNRs) located in the kidney of several avian and mammalian species, including humans. We hypothesized that single nucleotide polymorphisms (SNPs) in the melatonin receptor 1A gene (MTNR1A) might influence the risk of calcium nephrolithiasis. METHODS We performed a systematic analysis of the MTNR1A gene in 246 recurrent calcium stone formers (136 men, 110 women; mean age 40.2 ± 12.0 years; body mass index 25.8 ± 4.5 kg/m2) and 269 healthy controls comparable for age and gender without a history of nephrolithiasis. RESULTS Two SNPs in Intron 1 of MTNR1A were significantly associated with calcium nephrolithiasis: rs13140012 (P = 0.0004) and rs6553010 (P = 0.009). The haplotypes resulting from the two SNPs were also differently distributed between stone formers and controls, the haplotype A-T being more represented among stone formers (P = 0.00001) and the haplotype T-C being more common in healthy controls (P = 0.00001). Preliminary functional studies showed that the SNP rs13140012 could modify the binding sites for transcription factors. CONCLUSION The results of this case-control study indicate a strong association between allelic variants of MTNR1A and recurrent calcium nephrolithiasis.
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Affiliation(s)
- Teresa Esposito
- Institute of Genetics and Biophysics, Italian National Research Council, Naples, Italy.
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Richter HG, Torres-Farfan C, Garcia-Sesnich J, Abarzua-Catalan L, Henriquez MG, Alvarez-Felmer M, Gaete F, Rehren GE, Seron-Ferre M. Rhythmic expression of functional MT1 melatonin receptors in the rat adrenal gland. Endocrinology 2008; 149:995-1003. [PMID: 18039783 DOI: 10.1210/en.2007-1009] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We previously demonstrated that melatonin is involved in the regulation of adrenal glucocorticoid production in diurnal primates through activation of MT1 membrane-bound melatonin receptors. However, whether melatonin has a similar role in nocturnal rodents remains unclear. Using an integrative approach, here we show that the adult rat adrenal gland expresses a functional MT1 melatonin receptor in a rhythmic fashion. We found that: 1) expression of the cognate mRNA encoding for the MT1 membrane-bound melatonin receptor, displaying higher levels in the day/night transition (1800-2200 h); 2) expression of the predicted 37-kDa MT1 polypeptide in immunoblots from adrenals collected at 2200 h but not 1000 h; 3) no expression of the MT2 melatonin receptor mRNA and protein; 4) specific high-affinity 2-[(125)I]iodomelatonin binding in membrane fractions and frozen sections from adrenals collected at 2200 h but not 0800 h (dissociation constant = 14.22 +/- 1.23 pm; maximal binding capacity = 0.88 +/- 0.02 fmol/mg protein); and 5) in vitro clock time-dependent inhibition of ACTH-stimulated corticosterone production by 1-100 nm melatonin, which was reversed by 1 microm luzindole (a melatonin membrane receptor antagonist). Our findings indicate not only expression but also high amplitude diurnal variation of functional MT1 melatonin receptors in the rat adrenal gland. It is conceivable that plasma melatonin may play a role to fine-tune corticosterone production in nocturnal rodents, probably contributing to the down slope of the corticosterone rhythm.
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Affiliation(s)
- Hans G Richter
- Instituto de Anatomia, Histologia, y Patologia, Facultad de Medicina, Universidad Austral de Chile, Casilla (P.O. Box) 567, Valdivia, Chile.
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Rahman MA, Azuma Y, Fukunaga H, Murakami T, Sugi K, Fukushi H, Miura K, Suzuki H, Shirai M. Serotonin and melatonin, neurohormones for homeostasis, as novel inhibitors of infections by the intracellular parasite chlamydia. J Antimicrob Chemother 2005; 56:861-8. [PMID: 16172105 DOI: 10.1093/jac/dki331] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES Chlamydiae are obligate intracellular bacteria, causing a variety of diseases, i.e. pneumonia, sexually transmitted disease, conjunctivitis and zoonosis. Tryptophan depletion by interferon-gamma (IFN-gamma) is the most important host defence system against chlamydial infection. Thus chlamydial tryptophan metabolism is thought to play key roles for IFN-gamma resistance, persistent infection and host/tissue tropisms. We tested tryptophan derivatives for activity against chlamydia-infected cells. METHODS Rates of chlamydial infection and sizes of the inclusions were evaluated by in vitro infection using three Chlamydiaceae species, Chlamydia trachomatis, Chlamydophila pneumoniae and Chlamydophila felis, which show significant divergence of tryptophan synthesis genes and different susceptibilities to IFN-gamma. RESULTS Melatonin and serotonin, which are recognized as neural hormones for maintenance of organism homeostasis, reduced chlamydial infection but not other bacterial growth tested here. Unlike IFN-gamma, melatonin limited infection of all three chlamydiae and the effects were not recovered by tryptophan supplementation. Melatonin treatment only of host cells could diminish infection and the infection reduction was neutralized by a pertussis toxin, an inhibitor of G proteins. Ligands of melatonin and serotonin receptors also hampered infection. CONCLUSIONS Inhibition mechanisms of chlamydial infection by melatonin and serotonin appear to be different from those of IFN-gamma and involve specific G-protein-coupled receptors. Melatonin is deemed to inhibit early progression of the chlamydial development cycle, such as establishment of intracellular infection and/or conversion from elementary body to reticulate body. Utilization of melatonin, serotonin or their derivatives may be advantageous for harmless prevention of chlamydial infection.
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Affiliation(s)
- Mohd Akhlakur Rahman
- Department of Microbiology, Yamaguchi University School of Medicine, 1-1-1, Minamikogushi, Ube, Yamaguchi 755-8505, Japan
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Rivera-Bermúdez MA, Masana MI, Brown GM, Earnest DJ, Dubocovich ML. Immortalized cells from the rat suprachiasmatic nucleus express functional melatonin receptors. Brain Res 2004; 1002:21-7. [PMID: 14988029 DOI: 10.1016/j.brainres.2003.12.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2003] [Indexed: 12/15/2022]
Abstract
Immortalized SCN2.2 cells retain most biochemical and biophysical characteristics of the native rat SCN including the expression of clock genes and circadian regulatory proteins, and its distinctive pacemaker function. This study assessed the expression and signaling of MT(1) and MT(2) melatonin receptors in SCN2.2 cells. SCN2.2 cells express MT(1) and MT(2) receptors mRNA as detected by RT-PCR. In situ hybridization with digoxigenin-labeled probes demonstrated that mRNA for MT(1) and MT(2) melatonin receptors is expressed mostly in cells with neuronal-like morphology, representing 10.8+/-2.2% and 9.8+/-0.2%, respectively, of the SCN2.2 cell population. MT(1) and MT(2) melatonin receptor proteins are expressed in both rat SCN2.2 cells and rat SCN tissue as demonstrated by Western blot analysis with specific receptor antiserum. Melatonin (0.1-100 nM) inhibited forskolin (20 microM)-stimulated cAMP formation in a dose-dependent manner and this effect was blocked by the competitive melatonin receptor antagonist luzindole (100-1000 nM). Furthermore, melatonin (1 nM) stimulated protein kinase C (PKC) activity by approximately 2-fold. The selective MT(2) receptor antagonist 4P-PDOT (100 nM) blocked this effect, indicating that the melatonin-mediated increase in PKC activity occurs through activation of MT(2) melatonin receptors. We conclude that SCN2.2 cells express functional melatonin receptors, providing an in vitro model to unveil the melatonin signaling pathway(s) involved in the regulation of circadian rhythms.
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Affiliation(s)
- Moisés A Rivera-Bermúdez
- Department of Molecular Pharmacology and Biological Chemistry, The Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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Ramírez-Rodríguez G, Meza I, Hernández ME, Castillo A, Benítez-King G. Melatonin induced cyclic modulation of vectorial water transport in kidney-derived MDCK cells. Kidney Int 2003; 63:1356-64. [PMID: 12631351 DOI: 10.1046/j.1523-1755.2003.00872.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Melatonin, newly synthesized by the pineal gland, is rapidly released to general circulation reaching a nanomolar concentration. Cyclic production of melatonin synchronizes body rhythms with the photoperiod. Moreover, changes in urine production and osmolarity have been observed in the kidney during the night. However, the precise mechanisms by which plasma-circulating melatonin modifies renal physiology are not clearly understood. METHODS Madin-Darby canine kidney (MDCK) cell monolayers transport water vectorially from the apical to the basolateral side forming blisters or domes. Transport in epithelial cells is regulated by tight junction sealing, ion pumps and channels, and cytoskeleton organization, among other processes. MDCK cells were used to study vectorial water transport to determine the role of microfilament organization and protein kinase C (PKC) in dome formation in culture conditions that mimic the cyclic pattern of melatonin circulation in plasma. RESULTS Melatonin cyclically increased dome formation by 50% and caused enlargement and thickening of stress fibers in cells surrounding the domes. Optimal increase in dome formation was observed at nanomolar concentrations of melatonin after 6 hours, concomitantly with a 28% decrease in the transepithelial electrical resistance, which remained low for up to 12 hours, without apparent change in fluorescein isothiocyanate (FITC)-dextran flux. A blockage in dome formation elicited by melatonin was observed in monolayers preincubated with the Na+-K+-ATPase or PKC inhibitors. CONCLUSION The results obtained indicate that melatonin cyclically modifies the transepithelial permeability in kidney-derived cells through PKC activation and microfilament reorganization, and supports the hypothesis that melatonin may synchronize daily body rhythms through cyclic cytoskeletal rearrangements.
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Affiliation(s)
- Gerardo Ramírez-Rodríguez
- Departamento de Neurofarmacología, Subdirección de Investigaciones Clínicas, Instituto Nacional de Psiquiatría, Ramón de la Fuente Muñiz, México D.F. México
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Zhao H, Pang SF, Poon AMS. Variations of mt1 melatonin receptor density in the rat uterus during decidualization, the estrous cycle and in response to exogenous steroid treatment. J Pineal Res 2002; 33:140-5. [PMID: 12220327 DOI: 10.1034/j.1600-079x.2002.02898.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The expression of mt1 receptor protein in the rat uterus was investigated using an anti-mt1 polyclonal antibody against the rat mt1 receptor. A melatonin receptor protein of 37 kDa was detectable by Western blotting in the rat uterine membrane preparations. Autoradiography with the melatonin ligand, 2-[125I]iodomelatonin, was used to localize melatonin receptors in the uterus of the estrous rats and to study the changes of melatonin receptors in pregnancy. Melatonin receptors were found to be localized in the estrous rat uterine antimesometrial stroma. As decidualization of the uterine stroma progressed during pregnancy, the melatonin binding sites were progressively reduced and became confined to the antimesometrial non-decidualized outer stroma. 2-[125I]Iodomelatonin binding sites were not seen in the mesometrial stromal cells during pregnancy. The role of ovarian hormones in the regulation of uterine melatonin receptors was examined by studying the binding at various phases of the estrous cycle, after ovariectomy with and without follow-on treatment of estradiol (E2), progesterone (P4) or both. 2-[125I]Iodomelatonin binding in the rat uterus fluctuated during the estrous cycle, being lowest during metestrus. Ovariectomy caused an almost 70% reduction of 2-[125I]iodomelatonin binding compared with the control. Injections of ovariectomized (OVX) rats with E2 or P4 alone or in combination for 11 days induced a partial restoration of 2-[125I]iodomelatonin binding in the OVX rats. The results show that mt1 melatonin receptors in the rat antimesometrial stroma are regulated by ovarian hormones.
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Affiliation(s)
- H Zhao
- Department of Physiology, Faculty of Medicine, The University of Hong Kong, Hong Kong, China
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Pang CS, Xi SC, Brown GM, Pang SF, Shiu SYW. 2[125I]Iodomelatonin binding and interaction with beta-adrenergic signaling in chick heart/coronary artery physiology. J Pineal Res 2002; 32:243-52. [PMID: 11982794 DOI: 10.1034/j.1600-079x.2002.01860.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
2[125I]Iodomelatonin ([125I]Mel) binding sites were characterized on membrane preparations of young chick hearts. [125I]Mel binding was rapid, saturable, stable, reversible, specific and of picomolar affinity and femtomolar density. Guanosine 5'-O-(3-thiotriphosphate) significantly lowered the binding affinity by one- to twofold, supporting G-protein linkage of melatonin receptors. Binding was detected as early as embryonic day-9 (E9), and increased steadily peaking at E13 before it slowly declined to about 15% of the peak level a week posthatch. Specific [125I]Mel binding was significantly increased by in ovo administration of inotropic agents dopamine and isoproterenol. Melatonin or 2-iodo-N-butanoyl-tryptamine inhibited isoproterenol-stimulated cAMP accumulation in primary heart cell cultures and the effect was attenuated after pretreatment with pertussis toxin (PTX). Localization of melatonin receptors using autoradiography showed intense labeling in the coronary arteries in all age groups whereas those in the myoblasts decreased as the heart matured. While the myoblasts and undifferentiated developing coronary arteries expressed melatonin MT1 receptor subtype in E11 hearts as detected by immunostaining with anti-MT1 receptor serum, immunoreactivities were observed mostly on the endothelium/subendothelium and smooth muscle cells of the well developed coronary vessels in posthatch hearts. Collectively, our data suggest the presence of PTX-sensitive, G protein-coupled melatonin receptors, whose expression is up-regulated by dopamine and isoproterenol, in the chick heart. Activation of these receptors, which include MT1 subtype, may modulate beta-adrenergic receptor-mediated cAMP signaling in the control of chick heart and coronary artery physiology.
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Affiliation(s)
- Celia S Pang
- Department of Physiology, University of Hong Kong, Hong Kong, China
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Abstract
Using 2[125I]iodomelatonin as the radioligand, we characterized 2[125I]iodomelatonin binding sites in guinea pig platelet membrane preparations. Saturation radioreceptor studies indicated that these 2[125I]iodomelatonin binding sites were of picomolar affinity and femtomolar density. The dissociation constant (Kd) and maximum number of receptor sites (Bmax) were 42.5 +/- 1.79 pM and 11.8 +/- 0.8 fmol/mg protein (n = 6), respectively. 2[125I]Iodomelatonin competition studies with indoles or drugs indicate the following rank order of potency: 2-iodomelatonin > melatonin > 6-chloromelatonin > 6-hydroxymelatonin > N-acetylserotonin > 5-methoxytryptophol, whereas serotonin and its analogs had less than 20% inhibition at 0.1 mM. Guanosine 5'-O-(3-thiotriphosphate) significantly increased the Kd by twofold suggesting that these binding sites are coupled to the guanine nucleotide binding proteins. Immunoblotting studies using anti-MT(1) IgG demonstrated one peptide blockable band with an apparent molecular mass of 37 kDa. Melatonin had no effect on prostacyclin or forskolin-stimulated intracellular 3',5'-cyclic adenosine monophosphate accumulation. A diurnal variation in binding density, which was abolished after the animals were adapted to constant light conditions, was observed. Age related studies demonstrated that Bmax increased as the animal matured. Physiological melatonin concentrations potentiated whereas those at pharmacological levels inhibited adenosine diphosphate- or arachidonic acid-stimulated platelet aggregation. Our study demonstrated G-protein coupled, saturable, reversible and highly specific picomolar affinity 2[125I]iodomelatonin binding sites in guinea pig platelets. Pharmocological and physiological data indicate that they may be different from the nanomolar [3H]melatonin binding sites in human platelets previously reported.
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Affiliation(s)
- Mabel Y C Yau
- Department of Physiology, The University of Hong Kong, China
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Kiefer T, Ram PT, Yuan L, Hill SM. Melatonin inhibits estrogen receptor transactivation and cAMP levels in breast cancer cells. Breast Cancer Res Treat 2002; 71:37-45. [PMID: 11859872 DOI: 10.1023/a:1013301408464] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We have previously demonstrated that the pineal hormone, melatonin, can inhibit the growth of estrogen receptor-alpha (ERalpha)-positive breast cancer cells and suppress ERalpha gene transcription. To investigate the relationship between the estrogen response pathway and melatonin's growth inhibition, ERalpha-positive MCF-7 human breast cancer cells were transiently transfected with an estrogen response element (ERE) luciferase reporter construct and then treated with melatonin (10(-9)-10(-6) M) for 30 min followed by 10(-9) M 17-beta-estradiol (E2) or treated with each compound alone. Melatonin pre-treatment significantly reduced E2-induced ERalpha transactivation and ERalpha-ERE binding activity. We also conducted experiments to determine if melatonin modulates cAMP levels in MCF-7 cells. Melatonin inhibited the forskolin-induced and E2-induced elevation of cAMP levels by 57 and 45%, respectively. These data indicate that melatonin can act as a biological modifier to affect ERalpha transcriptional activity by regulating signal transduction pathways which impinge on the ERalpha and by altering E2-mediated ERalpha transactivation and ERalpha DNA binding activity.
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Affiliation(s)
- T Kiefer
- Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, LA 70112, USA
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Ching AC, Hughes MR, Poon AM, Pang SF. Melatonin receptors and melatonin inhibition of duck salt gland secretion. Gen Comp Endocrinol 1999; 116:229-40. [PMID: 10562453 DOI: 10.1006/gcen.1999.7362] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Most of the NaCl ingested by marine birds is reabsorbed from renal filtrate and excreted by the cephalic salt glands as a hypertonic NaCl secretion (SGS). Ducks have salt glands and their kidney cells have melatonin receptors. Melatonin affects glomerular filtration rate and tubular uptake of sodium (Na(+)) in mammals. We hypothesized that (1) duck salt glands also have melatonin receptors and (2) melatonin affects extrarenal Na(+) secretion. Both hypotheses were accepted because putative melatonin receptors were identified by 2¿(125)Iĭodomelatonin binding in salt glands of Pekin ducks, Anas platyrhynchos, and because melatonin inhibited SGS in these ducks. Saline ingestion increased B(max), but not K(d), of salt gland receptors. The duration of NaCl infusion needed to stimulate SGS was positively related with preinfusion plasma melatonin concentration (¿mel(pl)). Raising ¿mel(pl) prior to NaCl infusion further delayed onset of secretion and decreased secretion rate and concentration without affecting plasma volume and Na(+) concentration. Abrupt increase in ¿mel(pl) during SGS immediately decreased the rate by 43%. Secretion rate remained lower than the control rate during the subsequent hour; secretion concentration was not affected. This is the first report of putative melatonin binding sites in avian salt glands. Melatonin slowed the onset of NaCl-induced salt gland secretion and decreased its rate.
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Affiliation(s)
- A C Ching
- Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, British Columbia, V6T 1Z4, Canada
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