What is c-Fos?
c-Fos is an immediate-early gene that is activated in central nervous system (CNS) neurons upon exposure to neurotransmitters or activating stimulation. The c-Fos protein is a member of a transcription factor complex that will activate other genes to respond to the initiated neuronal activity. The unique rapid response of c-Fos to activating signals makes it an excellent marker of cell activation within the CNS.
Looking at c-Fos in a new light
Being an established marker of neuronal activation, c-Fos has been used for decades in classical immunohistochemistry. Countless studies have demonstrated how c-Fos protein is upregulated in response to changes in physiology or drug treatment. However, due to the time-consuming process of tissue sectioning, these studies usually focuses on pre-selected brain regions. A breakthrough came in 2016 where Renier et al. combined c-Fos detection with light sheet microscopy and generated the first whole brain map of c-Fos activity.
Innovations in c-Fos Imaging
Gubra’s approach to c-Fos imaging
Being a contract research organization (CRO) in the metabolic space we initially focused on c-Fos activation in response to obesity drugs, as seen in Hansen et al., 2021. But in recent years we have also applied whole brain c-Fos imaging to a range of fields including psychedelic drugs, schizophrenia research, and even physiological responses. Common for all studies is that we are able to map each individual c-Fos cell to our in-house atlas to determine where in the brain it was activated. By utilizing c-Fos imaging, we are able to identify regions of the brain that could be crucial for targeting a variety of diseases and disease states.
How does it work?
To achieve high-quality 3D c-Fos maps, samples are cleared to allow light penetration to even the deepest regions of the brain. Antibodies targeting c-Fos protein are then introduced to the transparent brain tissue and allowed to fully saturate the tissue. Following this, the brains are imaged, the data are grouped by condition, and the results are registered into our brain 3D atlas.
After quantification and mapping, the data are made available via our cloud based platform, GubraView, and curated videos of your images are generated by our 3D imaging team for use in presentations and to further analyze your data.
Creating a Comprehensive Brain Atlas
Significance of the Gubra mouse brain atlas
The Gubra atlas that we use for mapping of c-Fos activity was created using autofluorescence scans from 140 young, male mouse brains (Perens et al 2020). Leveraging the anatomical segmentation from the Allen brain atlas, we can identify individual neurons within each of the 1000+ brain regions annotated in the mouse brain.
Overlaying the data from each c-Fos group into this atlas allows for quantification of the expression profiles of each condition. We can then combine the expression profiles of each brain to create an “average” brain for each group. These “average” brains are then compared, and z-scores are generated to determine significance of the c-Fos signals in any region of interest, and by proxy identify regions of the brain that are activated by a therapy significantly more than the vehicle or other controls.
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- Download the publication: “An Optimized Mouse Brain Atlas for Automated Mapping and Quantification of Neuronal Activity Using iDISCO+ and Light Sheet Fluorescence Microscopy” here
Using c-Fos to map the activity of obesity drugs
An example of this c-Fos activation mapping is found in our publication focusing on identifying regions of the brain activated by obesity treatments for future targeting. The maps can be browsed at www.neuropedia.dk which is an open access version of GubraView.
- Download the publication: “Whole-brain activation signatures of weight-lowering drugs” here
Order c-Fos imaging for your projects or talk to one of our scientists to design a study using 3D imaging of c-Fos
c-Fos imaging stands as a powerful tool in neuroscience, providing unparalleled insights into brain activity and function. Researchers can leverage Gubra’s expertise in 3D imaging and c-Fos quantification for their projects. By contacting Gubra’s scientists, you can design studies utilizing 3D imaging of c-Fos and other markers, pushing the boundaries of CNS research. For more information or to discuss project ideas, reach out to Gubra’s experts here.
