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Obregón-Mendoza MA, Arias-Olguín II, Estévez-Carmona MM, Meza-Morales W, Alvarez-Ricardo Y, Toscano RA, Arenas-Huertero F, Cassani J, Enríquez RG. Non-Cytotoxic Dibenzyl and Difluoroborate Curcuminoid Fluorophores Allow Visualization of Nucleus or Cytoplasm in Bioimaging. Molecules 2020; 25:molecules25143205. [PMID: 32674349 PMCID: PMC7397183 DOI: 10.3390/molecules25143205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/10/2020] [Accepted: 07/11/2020] [Indexed: 01/27/2023] Open
Abstract
Curcumin, the most important secondary metabolite isolated from Curcuma longa, is known for its numerous purported therapeutic properties and as a natural dye. Herein, based on curcumin's intrinsic fluorescence, a search for improved curcumin-based fluorophores was conducted. Within the set of semi-synthetic curcumin derivatives i.e. mono (1), di (2), tri (3), tetra (4) benzylated and dibenzyl-fluoroborate (5), the fluorescence properties of 2 and 5 in solution outstood with a two-fold quantum yield compared to curcumin. Furthermore, all benzylated derivatives showed a favorable minimal cytotoxic activity upon screening at 25 μM against human cancer and non-tumoral COS-7 cell lines, with a reduction of its cytotoxic effect related to the degree of substitution. Fluorophores 2 and 5 are versatile bioimaging tools, as revealed by Confocal Fluorescence Microscopy (CFM), and showed permeation of living cell membranes of astrocytes and astrocytomas. When 2 is excited with a 405- (blue) or 543-nm (green) laser, it is possible to exclusively and intensively visualize the nucleus. However, the fluorescence emission fades as the laser wavelength moves towards the red region. In comparison, 5 allows selective visualization of cytoplasm when a 560-nm laser is used, showing emission in the NIR region, while it is possible to exclusively observe the nucleus at the blue region with a 405-nm laser.
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Affiliation(s)
- Marco A. Obregón-Mendoza
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de México 04510, Mexico; (M.A.O.-M.); (I.I.A.-O.); (W.M.-M.); (Y.A.-R.); (R.A.T.)
| | - Imilla I. Arias-Olguín
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de México 04510, Mexico; (M.A.O.-M.); (I.I.A.-O.); (W.M.-M.); (Y.A.-R.); (R.A.T.)
| | - M. Mirian Estévez-Carmona
- Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Wilfrido Massieu SN, Ciudad de México 07738, Mexico;
| | - William Meza-Morales
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de México 04510, Mexico; (M.A.O.-M.); (I.I.A.-O.); (W.M.-M.); (Y.A.-R.); (R.A.T.)
| | - Yair Alvarez-Ricardo
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de México 04510, Mexico; (M.A.O.-M.); (I.I.A.-O.); (W.M.-M.); (Y.A.-R.); (R.A.T.)
| | - Rubén A. Toscano
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de México 04510, Mexico; (M.A.O.-M.); (I.I.A.-O.); (W.M.-M.); (Y.A.-R.); (R.A.T.)
| | - Francisco Arenas-Huertero
- Laboratorio de Investigación en Patología Experimental, Hospital Infantil de México Federico Gómez, Ciudad de México 06720, Mexico;
| | - Julia Cassani
- Departamento de Sistemas Biológicos, Universidad Autónoma Metropolitana, Unidad Xochimilco, Ciudad de México 04960, Mexico;
| | - Raúl G. Enríquez
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de México 04510, Mexico; (M.A.O.-M.); (I.I.A.-O.); (W.M.-M.); (Y.A.-R.); (R.A.T.)
- Correspondence: ; Tel.: +52-55-5622-4404
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González-Andrade M, Rodríguez-Sotres R, Madariaga-Mazón A, Rivera-Chávez J, Mata R, Sosa-Peinado A, Del Pozo-Yauner L, Arias-Olguín II. Insights into molecular interactions between CaM and its inhibitors from molecular dynamics simulations and experimental data. J Biomol Struct Dyn 2015; 34:78-91. [PMID: 25702612 DOI: 10.1080/07391102.2015.1022225] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [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: 10/24/2022]
Abstract
In order to contribute to the structural basis for rational design of calmodulin (CaM) inhibitors, we analyzed the interaction of CaM with 14 classic antagonists and two compounds that do not affect CaM, using docking and molecular dynamics (MD) simulations, and the data were compared to available experimental data. The Ca(2+)-CaM-Ligands complexes were simulated 20 ns, with CaM starting in the "open" and "closed" conformations. The analysis of the MD simulations provided insight into the conformational changes undergone by CaM during its interaction with these ligands. These simulations were used to predict the binding free energies (ΔG) from contributions ΔH and ΔS, giving useful information about CaM ligand binding thermodynamics. The ΔG predicted for the CaM's inhibitors correlated well with available experimental data as the r(2) obtained was 0.76 and 0.82 for the group of xanthones. Additionally, valuable information is presented here: I) CaM has two preferred ligand binding sites in the open conformation known as site 1 and 4, II) CaM can bind ligands of diverse structural nature, III) the flexibility of CaM is reduced by the union of its ligands, leading to a reduction in the Ca(2+)-CaM entropy, IV) enthalpy dominates the molecular recognition process in the system Ca(2+)-CaM-Ligand, and V) the ligands making more extensive contact with the protein have higher affinity for Ca(2+)-CaM. Despite their limitations, docking and MD simulations in combination with experimental data continue to be excellent tools for research in pharmacology, toward a rational design of new drugs.
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Affiliation(s)
- Martin González-Andrade
- a Facultad de Medicina , Universidad Nacional Autónoma de México (UNAM) , México Distrito Federal , CP 04510 , México.,c Unidad de Vinculación de la Facultad de Medicina , UNAM en el INMEGEN , Secretaría de Salud, México Distrito Federal , CP 14610 , México
| | - Rogelio Rodríguez-Sotres
- b Facultad de Química , Universidad Nacional Autónoma de México (UNAM) , México Distrito Federal , CP 04510 , México
| | - Abraham Madariaga-Mazón
- b Facultad de Química , Universidad Nacional Autónoma de México (UNAM) , México Distrito Federal , CP 04510 , México
| | - José Rivera-Chávez
- b Facultad de Química , Universidad Nacional Autónoma de México (UNAM) , México Distrito Federal , CP 04510 , México
| | - Rachel Mata
- b Facultad de Química , Universidad Nacional Autónoma de México (UNAM) , México Distrito Federal , CP 04510 , México
| | - Alejandro Sosa-Peinado
- a Facultad de Medicina , Universidad Nacional Autónoma de México (UNAM) , México Distrito Federal , CP 04510 , México
| | - Luis Del Pozo-Yauner
- c Unidad de Vinculación de la Facultad de Medicina , UNAM en el INMEGEN , Secretaría de Salud, México Distrito Federal , CP 14610 , México
| | - Imilla I Arias-Olguín
- d Unidad de Biología Molecular y Medicina Genómica del Instituto de Investigaciones Biomédicas de la Universidad Nacional Autónoma de México (UNAM) , México Distrito Federal , CP 04510 , México.,e Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán , México Distrito Federal , CP 14000 , México
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Abstract
We have recently examined slow inactivation of Shab channels. Here we extend our characterization of Shab slow inactivation by presenting the properties of recovery from inactivation. The observations support our proposal that Shab reaches the same inactivated state either from open or closed states and suggest that closed and open state inactivation share the same mechanism. Regarding the latter, we also show that external K (+) and TEA slow down recovery from inactivation in agreement with the hypothesis that the mechanism of Shab inactivation qualitatively differs from C-type inactivation.
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Affiliation(s)
- Imilla I Arias-Olguín
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad Universitaria, México D.F., México
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Carrillo E, Arias-Olguín II, Islas LD, Gómez-Lagunas F. Shab K (+) channel slow inactivation: a test for U-type inactivation and a hypothesis regarding K (+) -facilitated inactivation mechanisms. Channels (Austin) 2013; 7:97-108. [PMID: 23419584 DOI: 10.4161/chan.23569] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Herein, we report the first characterization of Shab slow inactivation. Open Shab channels inactivate within seconds, with two voltage-independent time constants. Additionally, Shab presents significant closed-state inactivation. We found that with short depolarizing pulses, shorter than the slowest inactivation time constant, the resulting inactivation curve has a marked U-shape, but as pulse duration increases, approaching steady-state conditions, the U-shape vanishes, and the resulting inactivation curves converge to the classical Boltzmann h∞ curve. Regarding the mechanism of inactivation, we found that external K (+) and TEA facilitate both open- and closed-state inactivation, while the cavity blocker quinidine hinders inactivation. These results together with our previous observations regarding the K (+) -dependent stability of the K (+) conductance, suggest the novel hypothesis that inactivation of Shab channels, and possibly that of other Kv channels whose inactivation is facilitated by K (+) , does not involve a significant narrowing of the extracellular entry of the pore. Instead, we hypothesize that there is only a rearrangement of a more internal segment of the pore that affects the central cavity and halts K (+) conduction.
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Affiliation(s)
- Elisa Carrillo
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México UNAM, México, D F México
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Arias-Olguín II, Carrillo E, Meza B, Balleza D, Gomez-Lagunas F. Celecoxib Promotes a Fast Inactivation Gating in Shab K+ Channels. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.2537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Arias-Olguín II, Soriano-García M, Gomez-Lagunas F. K+ Occupancy of the Pore Critically Determines the Selectivity-Stability of K+ Channels. A Study with Shab Channels. Biophys J 2010. [DOI: 10.1016/j.bpj.2009.12.636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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Salazar H, Jara-Oseguera A, Hernández-García E, Llorente I, Arias-Olguín II, Soriano-García M, Islas LD, Rosenbaum T. Structural determinants of gating in the TRPV1 channel. Nat Struct Mol Biol 2009; 16:704-10. [PMID: 19561608 DOI: 10.1038/nsmb.1633] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Accepted: 06/04/2009] [Indexed: 12/23/2022]
Abstract
Transient receptor potential vanilloid 1 (TRPV1) channels mediate several types of physiological responses. Despite the importance of these channels in pain detection and inflammation, little is known about how their structural components convert different types of stimuli into channel activity. To localize the activation gate of these channels, we inserted cysteines along the S6 segment of mutant TRPV1 channels and assessed their accessibility to thiol-modifying agents. We show that access to the pore of TRPV1 is gated by S6 in response to both capsaicin binding and increases in temperature, that the pore-forming S6 segments are helical structures and that two constrictions are present in the pore: one that impedes the access of large molecules and the other that hampers the access of smaller ions and constitutes an activation gate of these channels.
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Affiliation(s)
- Héctor Salazar
- Departamento de Biofísica, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México, D.F., México
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Arias-Olguín II, Vitko I, Fortuna M, Baumgart JP, Sokolova S, Shumilin IA, Van Deusen A, Soriano-García M, Gomora JC, Perez-Reyes E. Characterization of the gating brake in the I-II loop of Ca(v)3.2 T-type Ca(2+) channels. J Biol Chem 2008; 283:8136-44. [PMID: 18218623 DOI: 10.1074/jbc.m708761200] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutations in the I-II loop of Ca(v)3.2 channels were discovered in patients with childhood absence epilepsy. All of these mutations increased the surface expression of the channel, whereas some mutations, and in particular C456S, altered the biophysical properties of channels. Deletions around C456S were found to produce channels that opened at even more negative potentials than control, suggesting the presence of a gating brake that normally prevents channel opening. The goal of the present study was to identify the minimal sequence of this brake and to provide insights into its structure. A peptide fragment of the I-II loop was purified from bacteria, and its structure was analyzed by circular dichroism. These results indicated that the peptide had a high alpha-helical content, as predicted from secondary structure algorithms. Based on homology modeling, we hypothesized that the proximal region of the I-II loop may form a helix-loop-helix structure. This model was tested by mutagenesis followed by electrophysiological measurement of channel gating. Mutations that disrupted the helices, or the loop region, had profound effects on channel gating, shifting both steady state activation and inactivation curves, as well as accelerating channel kinetics. Mutations designed to preserve the helical structure had more modest effects. Taken together, these studies showed that any mutations in the brake, including C456S, disrupted the structural integrity of the brake and its function to maintain these low voltage-activated channels closed at resting membrane potentials.
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