HKUST Engineers Create CarGAP: Innovative Vitamin B₁₂ and Light-Controlled Molecular Valve for Precise Cell Communication Regulation
Researchers at The Hong Kong University of Science and Technology (HKUST) have introduced a novel chemo-optogenetic tool named CarGAP, designed to regulate gap junctions—microscopic channels that enable direct communication between cells. This approach employs vitamin B₁₂ and green light to precisely open and close these intercellular channels, facilitating enhanced control over important cellular molecules and electrical signals.
Significance of CarGAP in Biological Research
CarGAP has been demonstrated in both mammalian cells and living fruit flies, providing a significant resource for investigating critical biological processes such as development, immunity, and neural activities. The tool holds potential implications for understanding various diseases and advancing regenerative medicine.
The Role of Gap Junctions
Gap junctions are essential for numerous physiological functions, acting as conduits for ions, second messengers, and small molecules necessary for coordinating cellular activities, including heart rhythms and brain functions. Dysfunction in these channels has been associated with several health issues, such as cardiovascular diseases and certain forms of cancer.
Challenges in Conventional Research
Traditional research methods have encountered challenges; for example, gene knockouts are permanent and indiscriminate, while chemical inhibitors may produce non-specific and toxic effects. Consequently, a precise mechanism capable of activating or deactivating gap junctions with minimal side effects has been a persistent need in cell and neurobiology.
Development of CarGAP
The primary challenge faced by the research team involved creating a biocompatible method for controlling gap junctions without disrupting cellular processes. Conventional optogenetic tools often rely on blue light, which can be harmful over prolonged exposure. The HKUST team sought a solution that would function across various species, from human cells to more complex organisms, while responding to non-toxic stimuli and allowing for genetic encoding.
Innovative Mechanism of Action
Guided by Professors Sun Fei and Xie Ting from the Department of Chemical and Biological Engineering and the Division of Life Science at HKUST, and in collaboration with Professor Zou Peng from Peking University, CarGAP was developed by integrating gap junction proteins with a light-sensitive vitamin B₁₂-binding domain derived from a bacterial protein. In the absence of light, the addition of vitamin B₁₂ leads to the aggregation of these domains, effectively blocking the channel. However, exposure to gentle green light causes disassembly of these protein aggregates, reopening the channel. This innovative design enables researchers to deactivate gap junctions using vitamin B₁₂ and reactivate them through light exposure.
Applications and Validation
The effectiveness of CarGAP has been validated across various applications, including the regulation of signaling molecule transfer in mammalian cells and the restoration of electrical coupling among cells. For example, the tool has been utilized to control the flow of the key signaling molecule cAMP between stem cells and their supporting niche cells in the ovaries of fruit flies, directly affecting stem cell behavior and egg development.
Publication of Findings
The research findings have been published in the *Proceedings of the National Academy of Sciences* (PNAS) under the title “Controllable gap junctions by vitamin B₁₂ and light.” The co-first authors of the study include HKUST PhD students Cui Duo and Huang Xinyu, along with Dr. Liu Shuzhang, a postdoctoral fellow from Peking University.
(Source: HKUST)
