isolation-quantification-axonal-mrnas-using-porous-membrane-inserts

Isolation and Quantification of Axonal mRNAs Using Porous Membrane Inserts and RTddPCR

The spatial dynamics of mRNA localization and translation within neurons are essential for various mechanisms of neuronal function, including neuronal ...

Rutgers University- Newark

Stress granules are membraneless organelles that serve as a protective cellular response to external stressors by sequestering non-translating messenger RNAs (mRNAs) and regulating protein synthesis. Stress granules formation mechanism is conserved across species, from yeast to mammals, and they play a critical role in minimizing cellular damage during stress. Composed of heterogeneous ribonucleoprotein complexes, stress granules are enriched not only in mRNAs but also in noncoding RNAs and various proteins, including translation initiation factors and RNA-binding proteins. Genetic mutations affecting stress granule assembly and disassembly can lead to abnormal stress granule accumulation, contributing to the progression of several diseases. Recent research indicates that stress granule dynamics are pivotal in determining their physiological and pathological functions, with acute stress granule formation offering protection and chronic stress granule accumulation being detrimental. This review focuses on the multifaceted roles of stress granules under diverse physiological conditions, such as regulation of mRNA transport, mRNA translation, apoptosis, germ cell development, phase separation processes that govern stress granule formation, and their emerging implications in pathophysiological scenarios, such as viral infections, cancer, neurodevelopmental disorders, neurodegeneration, and neuronal trauma.

Stress granules: Guardians of cellular health and triggers of disease.

Depletion or inhibition of core stress granule proteins, G3BP1 in mammals and TIAR-2 in , increases the growth of spontaneously regenerating axons. Inhibition of G3BP1 by expression of its acidic or "B-domain" accelerates axon regeneration after nerve injury, bringing a potential therapeutic strategy for peripheral nerve repair. Here, we asked whether G3BP1 inhibition is a viable strategy to promote regeneration in injured mammalian central nervous system (CNS) where axons do not regenerate spontaneously. G3BP1 B-domain expression was found to promote axon regeneration in the transected spinal cord provided with a permissive peripheral nerve graft (PNG) as well as in crushed optic nerve. Moreover, a cell-permeable peptide (CPP) to a subregion of B-domain (rodent G3BP1 amino acids 190 to 208) accelerated axon regeneration after peripheral nerve injury and promoted regrowth of reticulospinal axons into the distal transected spinal cord through a bridging PNG. G3BP1 CPP promoted axon growth from rodent and human neurons cultured on permissive substrates, and this function required alternating Glu/Asp-Pro repeats that impart a unique predicted tertiary structure. The G3BP1 CPP disassembles axonal G3BP1, G3BP2, and FMRP, but not FXR1, granules and selectively increases axonal protein synthesis in cortical neurons. These studies identify G3BP1 granules as a key regulator of axon growth in CNS neurons and demonstrate that disassembly of these granules promotes retinal axon regeneration in injured optic nerve and reticulospinal axon elongation into permissive environments after CNS injury. This work highlights G3BP1 granule disassembly as a potential therapeutic strategy for enhancing axon growth and neural repair.

Disruption of G3BP1 granules promotes mammalian CNS and PNS axon regeneration.

Neuronal growth and regeneration are regulated by local translation of mRNAs in axons. We examined RNA polyadenylation changes upon sensory neuron injury and found upregulation of a subset of polyadenylated B2-SINE repeat elements, hereby termed GI-SINEs (growth-inducing B2-SINEs). GI-SINEs are induced from ATF3 and other AP-1 promoter-associated extragenic loci in injured sensory neurons but are not upregulated in lesioned retinal ganglion neurons. Exogenous GI-SINE expression elicited axonal growth in injured sensory, retinal, and corticospinal tract neurons. GI-SINEs interact with ribosomal proteins and nucleolin, an axon-growth-regulating RNA-binding protein, to regulate translation in neuronal cytoplasm. Finally, antisense oligos against GI-SINEs perturb sensory neuron outgrowth and nucleolin-ribosome interactions. Thus, a specific subfamily of transposable elements is integral to a physiological circuit linking AP-1 transcription with localized RNA translation.

Article	Year
Stress granules: Guardians of cellular health and triggers of disease. Neural regeneration research\| PubMed ID: 39995077	2026
Disruption of G3BP1 granules promotes mammalian CNS and PNS axon regeneration. Proceedings of the National Academy of Sciences of the United States of America\| PubMed ID: 40014573	2025
Repeat-element RNAs integrate a neuronal growth circuit. Cell\| PubMed ID: 40381624	2025
Stress Granules as Molecular Echoes of Gut Inflammation. Cellular and molecular gastroenterology and hepatology\| PubMed ID: 41386481	2025

Pabitra K. Sahoo

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