[Glutamic acid as a universal extracellular signal]

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Context:

• Traditionally, glutamic acid (Glu) and gamma-aminobutyric acid (GABA) are recognized as primary neurotransmitters within the central nervous system.
• The role and expression of amino acidergic signaling machinery in non-neuronal cells remain underexplored.
• Recent research indicates the presence and function of Glu receptors outside the brain.

Purpose:

• To review recent findings on the physiological and pathological significance of neuronal amino acids as extracellular signals in diverse cell types.
• To highlight the role of amino acid signaling in maintaining homeostasis and its implications in disease.
• To explore the functional expression of glutamatergic and GABAergic signaling in non-neuronal cells.

Summary:

• Functional glutamatergic and GABAergic signaling pathways are present in undifferentiated neural progenitor cells.
• Glu is involved in suppressing proliferation in undifferentiated mesenchymal stem cells.
• Accumulating evidence supports the role of neuronal amino acids as common extracellular autocrine or paracrine signals in various cell types.

Impact:

• Demonstrates that amino acids like Glu and GABA act as vital extracellular signals in a wide range of cells, essential for homeostasis.
• Suggests potential therapeutic strategies by evaluating existing drugs for conditions related to amino acid signaling disturbances.
• Opens new avenues for understanding and treating diseases linked to dysregulated amino acid neurotransmission in diverse organs.