Cell behavior is a tightly regulated, finely tuned process where various different signals work together to elicit a specific response. Unraveling these mechanisms allows us to understand how cells are usually regulated when the cell is in a normal state. These insights can then be used to understand how these processes are disrupted in the initiation and progression of oncological, neurodegenerative, and immunological diseases, as well as identify novel biomarkers and therapeutic treatment targets.
Tissue culture cells are often used as a model system to investigate the pathways that regulate these pathways. However, it may be necessary to treat your cells with modulators because the event being studied may not exist in the cell’s natural state. After all, looking for the mechanisms involved in cell senescence will be challenging if the cells are still proliferating and investigating apoptosis can be difficult in cells that aren’t apoptotic. For example, caspase-3 is a crucial mediator of apoptosis that is activated once it is cleaved at Asp175. The cleaved form of caspase-3 is only detected in apoptotic cells, so cells must be treated by a modulator (like staurosporine) to drive the cells into apoptosis and explore the role of caspase-3 effector proteins and downstream signaling events.
Other examples include HIF-1a, a protein that is only expressed in hypoxic cells. Cells need to be modulated with a hydroxylase inhibitor (like cobalt chloride) to drive normal cells into hypoxia to induce expression before HIF-1a and related signaling proteins and pathways can be studied. On the flip side, nuclear lysates can also be enriched by using the proteosome inhibitor MG132 to inhibit HIF-1α ubiquitination.
Treating cells with a modulator modifies proteins that play a part in a specific cellular event, so the protein or cell will exhibit conditions you need to advance your research. With the complexity in how processes are regulated and the crosstalk that occurs between different signaling pathways, you’ll most likely have to perform multiple experiments in order to generate all of the necessary information needed to definitively confirm your hypothesis. For the same reason, peer reviewers often require both stimulatory and inhibitory effects prove a theory. For example, if activating a protein causes a cell to migrate, then you’ll also need to show that inhibiting the protein prevents the cell from migrating.
Modulators include chemical inhibitors and activators, which are synthetic molecules that can promote or inhibit a specific cellular event, and cytokines or growth factors, which are biological molecules that exist and function in vivo. All modulators are an important tool in your research arsenal. They can be used to stimulate proteins into the activated form, inhibit a protein if it is normally activated, or enrich for a specific protein state if it is undetectable under normal conditions. Using modulators help you:
- Answer questions about the role of specific signaling nodes in disease
- Study cancer resistance mechanisms by inhibiting a primary pathway to look at the activation of alternative pathways
- Investigate factors related to Alzheimer’s disease progression by stimulating amyloid β
- Explore how cytokine storms are triggered by modulating the behavior of immune cells like macrophages, neutrophils, and NK cells
- Identify protein interactions or kinase substrates through the activation or inhibition of an individual signaling node.
Just to name a few!