Immediate early genes (IEGs) are genes which are activated transiently and rapidly in response to a wide variety of cellular stimuli. They represent a standing response mechanism that is activated at the transcription level in the first round of response to stimuli, before any new proteins are synthesized. IEGs are distinct from "late response" genes, which can only be activated later, following the synthesis of early response gene products. Thus IEGs have been called the "gateway to the genomic response". The term can describe viral regulatory proteins that are synthesized following viral infection of a host cell, or cellular proteins that are made immediately following stimulation of a resting cell by extracellular signals.
In their role as "gateways to genomic response", many IEG products are natural transcription factors or other DNA-binding proteins. However, other important classes of IEG products include secreted proteins, cytoskeletal proteins, and receptor subunits. Neuronal IEGs are used prevalently as a marker to track brain activities in the context of memory formation and development of psychiatric disorders. IEGs are also of interest as a therapeutic target for treatment of human cytomegalovirus.
The earliest identified and best characterized IEGs include c-fos, c-myc and c-jun, genes that were found to be homologous to retroviral oncogenes. Thus IEGs are well known as early regulators of cell growth and differentiation signals. However, other findings suggest roles for IEGs in many other cellular processes.
Expression of IEGs occurs in response to internal and external cell signals, occurring rapidly without the need to synthesize new transcription factors. The genetic sequences of IEGs are generally shorter in length (~19kb) and exhibit an enrichment of specific transcription factor binding sites, offering redundancy in transcription initiation. Translation of IEG mRNA into proteins occurs regardless of protein synthesis inhibitors which disrupts the process of protein production.
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Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, it would be impossible for language, relationships, or personal identity to develop. Memory loss is usually described as forgetfulness or amnesia. Memory is often understood as an informational processing system with explicit and implicit functioning that is made up of a sensory processor, short-term (or working) memory, and long-term memory.
While the cellular and molecular mechanisms of learning and memory have long been a central focus of neuroscience, it is only in recent years that attention has turned to the epigenetic mechanisms behind the dynamic changes in gene transcription responsible for memory formation and maintenance. Epigenetic gene regulation often involves the physical marking (chemical modification) of DNA or associated proteins to cause or allow long-lasting changes in gene activity.
Learning is the process of acquiring new understanding, knowledge, behaviors, skills, values, attitudes, and preferences. The ability to learn is possessed by humans, animals, and some machines; there is also evidence for some kind of learning in certain plants. Some learning is immediate, induced by a single event (e.g. being burned by a hot stove), but much skill and knowledge accumulate from repeated experiences. The changes induced by learning often last a lifetime, and it is hard to distinguish learned material that seems to be "lost" from that which cannot be retrieved.
Explores optogenetic tools for probing neuronal activity using light and calcium-gated tools, discussing their applications in neuroscience and beyond.
A memory engram is thought to be the physical substrate of the memory trace within the brain, which is generally depicted as a neuronal ensemble activated by learning to fire together during encoding and retrieval. It has been postulated that engram cell e ...
FRONTIERS MEDIA SA2023
Information derived from experiences is incorporated into the brain as changes to ensembles of cells, termed engram cells, which allow memory storage and recall. The mechanism by which those changes hold specific information is unclear. Here, we test the h ...
The lateral amygdala (LA) encodes fear memories by potentiating sensory inputs associated with threats and, in the process, recruits 10-30% of its neurons per fear memory engram. However, how the local network within the LA processes this information and w ...