RBM3 is a protein found within human cells. Formally known as RNA-Binding Motif Protein 3, it is encoded by the RBM3 gene. It is present across all human tissues, though its concentration can vary depending on conditions. RBM3 is involved in fundamental biological processes, making it important for understanding cellular function and various health conditions.
Understanding RBM3’s Molecular Role
At a molecular level, RBM3 functions as an RNA-binding protein, directly interacting with RNA molecules within the cell. It belongs to the cold-shock domain family of RNA-binding proteins and possesses an RNA recognition motif (RRM) domain, specialized for binding to RNA. RBM3 is primarily located in the cytoplasm, the jelly-like substance filling the cell, where it regulates messenger RNA (mRNA).
Its general function involves influencing gene expression and protein synthesis, which are fundamental processes for cell life. RBM3 modulates the efficiency of translation, the process by which genetic information from mRNA is converted into proteins. It also affects mRNA stability and localization, ensuring that genetic instructions are available and correctly positioned for protein production. The protein achieves this by interacting with various mRNAs and other RNA-binding proteins, and enhances protein synthesis.
RBM3 as a Cellular Protector
Beyond its general molecular functions, RBM3 plays a notable role in helping cells respond to and survive various challenging conditions. It is recognized as a “cold-shock protein” because its expression increases significantly when cells are exposed to cooler temperatures, such as mild to moderate hypothermia. This heightened expression under cold stress promotes cell survival by enhancing protein synthesis, which is often inhibited during such conditions.
The protein also contributes to cellular resilience under other stressors, including low oxygen levels, known as hypoxia. RBM3 helps protect cells against various forms of damage, including those induced by hyperthermia, serum deprivation, radiation, and exposure to certain toxins and drugs. Its presence is associated with anti-apoptotic effects, meaning it helps prevent programmed cell death, maintaining cell viability under duress. This protective capacity underscores its broader role in maintaining cellular integrity and function in adverse environments.
RBM3’s Influence on Brain Health
RBM3 holds significant implications for neurological function and disease, largely due to its neuroprotective properties. This protein is abundantly expressed in the brain, particularly in younger individuals. It has been shown to mitigate cell death in models of neurodegenerative conditions.
RBM3 is involved in structural plasticity, the continuous remodeling of synapses, which are the connections between brain cells. In mouse models of neurodegenerative diseases, such as prion-infected and Alzheimer’s-type mice, the ability to regenerate synapses after cooling declines with a failure to induce RBM3. Boosting RBM3 expression in the hippocampus, a brain region involved in memory, has been observed to prevent this deficit and restore the capacity for synapse reassembly after cooling.
Enhanced RBM3 levels, whether induced by cooling or direct delivery, have resulted in sustained synaptic protection in these mouse models, preventing behavioral deficits, reducing neuronal loss, and significantly prolonging survival. RBM3 achieves some of its neuroprotective effects by increasing local protein synthesis in dendrites and global protein synthesis. The induction of RBM3 in neurons during cooling is regulated by the activation of TrkB receptors, suggesting a specific pathway for its neuroprotective effects.
RBM3 and Cancer
The role of RBM3 in various cancers is complex and can appear contradictory, often depending on the specific type of cancer. In some contexts, RBM3 can act as a proto-oncogene, promoting cell proliferation and preventing a process called mitotic catastrophe, where cells die during cell division. Its expression has been linked to increased cell growth and the development of anchorage-independent growth, a hallmark of cancer.
Studies have shown elevated RBM3 levels in more aggressive prostate cancer and high-grade astrocytoma, where it can predict earlier recurrence. Furthermore, RBM3 has been demonstrated to confer resistance to certain chemotherapeutic agents like cisplatin and doxorubicin. Conversely, in other cancer types, such as colorectal cancer, breast cancer, and melanoma, high RBM3 expression has been associated with a favorable prognosis, indicating decreased tumor progression or increased disease-free survival. This dual nature highlights the ongoing research efforts to fully understand RBM3’s precise mechanisms in different cancers and its potential as a diagnostic marker or a target for therapeutic interventions.