Many bodily functions are based on the force and displacement generated by contraction of muscles. The switch from rest to contraction and back is dictated by the rapid movements of calcium (Ca) ions between compartments — or organelles — in the muscle cell. We want to understand the mechanisms that control these movements in skeletal and cardiac muscles.
Our work
We study the molecules that control Ca movements. Key to their role are their interactions, which can be mutual, and with Ca and other ions in the environment of the cell.
In early work, the lab contributed to the identification of the main two proteins dedicated to these tasks: a “voltage sensor” in the outer membrane of the contractile cell and the “RyR,” a channel in the membrane of the organelle where Ca is stored, the sarcoplasmic reticulum. The voltage sensor detects the command to contract, an electrical action potential coming from the brain through nerves, and converts this to a control signal to the RyR channel. The signal causes the channel to open, so that Ca is released and can switch contraction on.
In later years, we have studied how this “forward” signal, from nerve to voltage sensor to RyR channel, is complemented by “feedback” signals, whereby the process of Ca release is finely controlled and eventually terminated. This revealed mechanisms inside the Ca store, including important roles of calsequestrin, a protein located inside the store with unique abilities to bind Ca ions and release them when needed.
As with other studies in the Department of Physiology & Biophysics, the focus on normal functions leads to an understanding of basic disease mechanisms that come about when the proteins are altered, by inheritable mutations or other causes. Recently, in collaboration with a Toronto clinic, we have described abnormalities in the three molecules mentioned, associated with several diseases of skeletal and cardiac muscle. The Toronto clinic sees the greatest numbers of these patients in the Americas.
Technology
Our lab uses techniques of electrophysiology, imaging of live specimens and optical monitoring of function, combined with ancillary molecular biology and protein chemistry. The data obtained experimentally are interpreted with quantitative modeling and simulation.
In addition, we have developed novel techniques:
- A 4-gap voltage clamp for single muscle cells
- A novel biosensor for imaging Ca concentration in the sarcoplasmic reticulum
- A “Snap-TAG” method to target small synthetic monitors to different cellular organelles
- Shifted Excitation and Emission Ratioing (SEER) of fluorescence, which is a method that increases the sensitivity of ratioing fluorescent monitors of concentration
- SEER applied to increase the sensitivity of monitors of membrane voltage
- A method to enhance the range of measurable concentrations using two monitors with the same fluorophore and different affinities.
- 3D-printed flow chambers for combining multiple operations in single- or multi-cell preparations, or cell cultures, including fast laminar perfusion, electrical stimulation, patch clamp and thermal control (patent pending #62149976).
Publications
Recent
Manno, Figueroa, et al. (2017.) “Calsequestrin depolymerizes when calcium is depleted in the sarcoplasmic reticulum of working muscle.” Proc Natl Acad Sci U S A. 2017 Jan 24;114(4):E638-E647.
Lewis, Munske, et al. (2016.) “Characterization of Post-Translational Modifications to Calsequestrins of Cardiac and Skeletal Muscle.” Int J Mol Sci. 2016 Sep 13;17(9).
Campos, Rios, et al. (2016.) “Alterations in zebrafish development induced by simvastatin: Comprehensive morphological and physiological study, focusing on muscle.” Exp Biol Med (Maywood). 2016 Nov;241(17):1950-1960.
Lewis, Ríos, Kang, et al. (2015.) “Human Calsequestrin Mutants in MH and VAg Myopathy.” J Biol Chem. 290: 28665-74.
Ríos, Figueroa, Manno, et al. (2015.) “The Couplonopathies. A Class of Diseases of Skeletal and Cardiac Muscle.” J. Gen. Physiol. 145: 459-74.
Breakthroughs
Ríos and Brum. (1987.) “Involvement of DHPRs in Excitation‑Contraction Coupling in Skeletal Muscle.” Nature. 325:717‑720.
Ríos and Pizarro. (1991.) “The Voltage Sensor of E‑C Coupling in Skeletal Muscle.” Physiol. Rev. 71:849-908.
Tsugorka, Ríos and Blatter. (1995.) “Imaging Elementary Events of Ca Release in Muscle…” Science. 269:1723-1726.
Stern, Pizarro and Ríos. (1997.) “A Local Control Model of Skeletal… Excitation-Contraction Coupling.” J. Gen. Physiol. 110:415-440.
Stern, Ríos, et al. (1999.) “Local control models of cardiac excitation-contraction coupling…” J. Gen. Physiol., 113:469-489.
González, Ríos, et al. (2000.) “Involvement of Multiple Release Channels in Ca Sparks of Muscle.” PNAS USA. 97:4380-4385.
Launikonis, Ríos, et al. (2005.) “Confocal Imaging of [Ca2+] in Cellular Organelles by SEER…” J. Physiol. 567:523-543.
Pouvreau, Zhou, et al. (2007.) “Ca2+ Sparks Operated by Voltage Require RyR3 in Skeletal Muscle.” PNAS USA. 104:5235-40.
Morgan, DeCoursey, et al. (2009.) “Proton Channels Maintain pH in Neutrophils During Phagocytosis.” PNAS USA. 106:18022-7.
Bannwarth, Johnsson, et al. (2010.) “Indo-1 Derivatives for Local Calcium Sensing.” ACS Chem. Biol. 4, 179-190.
Ríos E. (2010.) “The Cell Boundary Theorem: A Simple Law of the Control of Cytosolic [Ca2+].” J Physiol Sci. 60:81-4.
Zhou, Deng, et al. (2010.) “Hyperactive Ca Signaling … in Model of Amyotrophic Lateral Sclerosis.” J Biol Chem. 285:705-12.
Sztretye, Ríos, et al. (2011.) “D4cpv-Calsequestrin: …Targeted to the Ca Store of Skeletal Muscle.” J. Gen. Physiol. 138:211-229.
Figueroa, Ríos, et al. (2012.) “Synthetic Localized Ca Transients Probe Mechanisms in Muscle …” J. Physiol. 590: 1389-1411.
Shkryl, Blatter and Ríos. (2012.) “Properties of Ca2+ Sparks Revealed by 4D Imaging of Cardiac Muscle.” J. Gen. Physiol. 139:189–207.
Manno, Ríos, et al. (2013.) “Dynamic Measurement of the Ca Buffering of the SR.” J Physiol. 591:423-42.
Manno and Ríos. (2013.) “Confocal Imaging of Transmembrane Voltage by SEER of di-8-ANEPPS.” J Gen Physiol. 141:371-87.
Stern, Ríos and Maltsev. (2013.) “Life and Death of a Cardiac Calcium Spark.” J Gen Physiol. 142:257-74. 2013.
A novel invited multimedia presentation
Ríos, E. (2012.) "Cell Boundary Theorem" in Simpson, A. (ed.), Ca Signaling…, The Biomedical & Life Sciences Collection, Henry Stewart Talks Ltd.
Funding
Ongoing
National Institute of General Medical Sciences 1R01GM111254-01: “Roles of Calsequestrin in the Control of Calcium Signals in Health and Disease” (10/01/14 – 09/31/18) . Principal investigator: Rios
Goal: Define the roles of calsequestrin in Ca signaling of skeletal and cardiac muscle. In particular we ask whether several properties of the reactions of calsequestrin with Ca, demonstrated in vitro—as well as the changes in these reactions brought about by disease linked mutations—actually apply in vivo, and help determine the disease phenotypes.
Recently completed
NIH/National Center for Research Resources (NCCR) S10 RR024707-01: “A Dual Scanner Confocal Microscope.” Principal investigator: Rios. In this shared instrumentation grant, we purchased a novel laser scanner to allow for detailed photostimulation of cells (for purposes like photorelease of Ca or other signals at specific locations), while imaging the response with high temporal resolution. This project was supplemented by the $750,000 Hasterlik Award from Rush University Philanthropy.
NIH/National Institute of Arthritis, Musculoskeletal and Skin Diseases (NIAMS) R01 AR032808-28: "Calcium Movements in Excitation-Contraction Coupling." Principal investigator: Rios. Implemented as a 10-year MERIT (Method to Extend Research in Time) award in 1996-2006. The project’s main goal was to understand the global or whole cell calcium signal of excitation contraction coupling in terms of the properties of the molecules involved.
NIH/NIAMS R01 AR049184-06: “Skeletal Muscle: Control of Calcium Release Within the Sarcoplasmic Reticulum.” Principal investigator: Rios. The main goal was to understand the role of calcium levels inside the sarcoplasmic reticulum in the control of the calcium signal of excitation-contraction coupling. A technical accomplishment was to dynamically measure/image the concentration of calcium inside the sarcoplasmic reticulum and other organelles.
Our team
The lab, alone or jointly with other groups within our Section of Cellular Signaling, has trained five senior faculty members, three assistant professors, 27 postdocs, eight graduate students and five physicians in cross-training. Most of these team members continue to contribute to the academic and scientific endeavors of our group.
Contact us
Eduardo Rios, PhD
Professor
Rush University
Department of Physiology & Biophysics
Jelke Building
1750 W. Harrison St., Room 1279
Chicago, IL 60612
Phone: (312) 942-2081
Fax: (312) 942-8711
Email: eduardo_rios@rush.edu
Carolina Figueroa, PhD
Assistant Professor
Jelke Building, Room 1267
Phone: (312) 942-4458
Email: lourdes_figueroa@rush.edu
Carlo Manno, PhD
Assistant Professor
Jelke Building, Room 1271
Phone: (312) 942-4464
Email: carlos_manno@rush.edu