Stress granules regulate stress-induced paraspeckle assembly

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Eukaryotic cells utilize RNA-protein (RNP) granules for cellular regulation.
• Paraspeckles (nuclear) and stress granules (cytoplasmic) are distinct RNP granules implicated in diseases like amyotrophic lateral sclerosis.
• The crosstalk between spatially separated RNP granules is largely unexplored.

Purpose of the Study:

• To investigate the relationship and potential crosstalk between paraspeckles and stress granules.
• To determine if stress granules influence paraspeckle formation or function.
• To elucidate the molecular mechanisms underlying SG-paraspeckle interactions.

Main Methods:

• Proteomic analysis of affinity-purified paraspeckle-like structures.
• Induction of stress granules using chemical and genetic methods.
• Microscopy to observe paraspeckle and stress granule assembly.
• Assessment of protein interactions and regulatory roles, including UBAP2L.

Main Results:

• Significant proteomic overlap identified between paraspeckles and stress granules.
• Stress-induced conditions promote paraspeckle hyperassembly.
• Formation of visible stress granules is essential for triggering and sustaining stress-induced paraspeckle assembly.
• Stress granules may sequester negative regulators like UBAP2L, thereby promoting paraspeckle formation.

Conclusions:

• Stress granules function as positive regulators of nuclear RNP granule assembly, specifically paraspeckles.
• A novel crosstalk mechanism between cytoplasmic stress granules and nuclear paraspeckles has been revealed.
• Disruption of this SG-paraspeckle crosstalk may contribute to the pathogenesis of human diseases.