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Optogenetic control of the ER calcium store release by a novel ER-localized photoactivated cation channel

English title Optogenetic control of the ER calcium store release by a novel ER-localized photoactivated cation channel
Applicant Hediger Matthias A.
Number 190714
Funding scheme Spark
Research institution Abteilung für Nephrologie Medizinische Universitäts-Kinderklinik Inselspital
Institution of higher education University of Berne - BE
Main discipline Molecular Biology
Start/End 01.12.2019 - 31.01.2021
Approved amount 117'326.00
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All Disciplines (3)

Discipline
Molecular Biology
Genetics
Physiology : other topics

Keywords (5)

Ion channels; Bioengineering; Optogenetics; Calcium signaling ; Store-Operated Calicum Entry

Lay Summary (German)

Lead
Um die genaue Rolle der Calcium-Signalgebung in der Zellphysiologie zu untersuchen, ist eine Methode zur Steuerung der Freisetzung von Calcium aus dem endoplasmatischen Retikulum (ER) wünschenswert. Zu diesem Zweck soll in diesem Projekt ein neuartiger Ansatz zur Auslösung der ER-Calciumfreisetzung über einen optogenetischen Regler entwickelt werden.
Lay summary

Die Freisetzung von Calcium aus dem endoplasmatischen Retikulum (ER) in das Cytosol unterliegt einer feinen Regulation zwecks Steuerung der normalen physiologischen Abläufe. Hierbei sind Calcium-Ionen im Cytosol ein wichtiger „second messenger“, da sie die intrazelluläre Signalgebung vermitteln. Um die genaue Rolle dieser Calcium-Signale in der Zellphysiologie zu untersuchen, ist ein Ansatz zur genauen Steuerung der Calcium-Freisetzung aus den ER-Speichern wünschenswert. Zu diesem Zweck soll in diesem Projekt eine neuartiger Methode zur raschen Auslösung der ER-Calciumfreisetzung über einen sogenannten optogenetischen Regler entwickelt werden. Die Steuerung dieser Freisetzung soll aus einer veränderten Version des Kationenkanals «Channelrhodopsin 2» bestehen, welcher sich in der ER-Membran befindet. Es wird erwartet, dass das Ergebnis dieses Bioengineering-Projekts für die biomedizinischen Forschung von grosser Nützlichkeit sein wird.

Direct link to Lay Summary Last update: 17.12.2019

Responsible applicant and co-applicants

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Associated projects

Number Title Start Funding scheme
204972 Modulation of calcium influx by Orai channel isoforms and pharmaceutical interventions 01.11.2021 Project funding (Div. I-III)

Abstract

Ca2+ regulates a wide array of physiological processes, from gene expression to cell differentiation, proliferation, muscle contraction and neurotransmission. The endoplasmic reticulum (ER) is a major intracellular Ca2+ store, which buffers excessive Ca2+ ions from cytoplasm and rapidly releases them when needed. The steep Ca2+ concentration gradient between cytoplasm and ER (up to 1:5000) is maintained through orchestrated cooperation of specialized Ca2+ pumps (SERCAs) and release channels in the ER (e.g. IP3, or ryanodine receptors), as well as the refilling mechanism called store-operated calcium entry (SOCE). The spatiotemporal patterning of Ca2+ signals and the localization of Ca2+-dependent effectors efficient translation into specific physiological responses. The highly dynamic nature of ER and membrane tethering proteins allows the ER to establish transient physical contacts with other organelles, thereby shaping the spatiotemporal patterns of Ca2+ signals within the eukaryotic cell. To investigate the role of ER-mediated Ca2+ signaling in cellular physiology, an approach to accurately control Ca2+ release from ER stores would be most desirable. Although numerous approaches to mobilize ER Ca2+ stores exist, none of them is entirely satisfactory. Thus, a specific tool that rapidly accomplishes this task in a well-controlled manner, without affecting other physiological processes that are ongoing in the cell, is definitively lackingThis SNF Spark project aims to bioengineer a novel optogenetic-controller for Ca2+ release from the ER stores. This envisioned tool will consist of an engineered cation channel, channelrhodopsin 2, which will be specifically targeted to the ER membrane (ER-ChR2). The channel can be effectively and transiently activated by pulses of blue light (470 nm). The main deliverables to be generated are 1) a new DNA mammalian expression vector encoding the ER-ChR2 channel and 2) a HEK293 cell line stably expressing this protein. While the widely-used pharmacological tools triggering release of ER Ca2+ stores (e.g. thapsigargin) only allow massive and largely uncontrolled release of Ca2+ ions into the cytosol, the herein proposed tool is expected to permit a level of fine-control of Ca2+release as never seen before. In fact, it will even likely allow the simulation of Ca2+ oscillations, mimicking physiological quantization of Ca2+ release. This is a high-risk/high-reward type of project that aims to generate an unconventional way to trigger ER calcium release, as a novel scientific tool to study the precise mechanisms of Ca2+ signaling. While preliminary data to demonstrate effectiveness of this optogenetic ER calcium release is still lacking, precluding financing through generally-available funding schemes, the outcome of this bioengineering project is expected to generate great benefits to the scientific community.
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