[Age-dependent changes in mRNA transport (nucleus-cytoplasm)]

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• Nuclear mRNA export is an essential ATP-dependent process for gene expression.
• This transport involves mRNA release, translocation through the nuclear pore, and cytoskeletal binding.

Purpose of the Study:

• To identify and characterize components involved in mRNA translocation through the nuclear pore.
• To investigate the impact of aging on mRNA transport mechanisms.

Main Methods:

• Purification of nuclear envelope (NE) proteins involved in mRNA translocation.
• Assays to measure NE nucleoside triphosphatase (NTPase) activity, protein kinase, and phosphatase activities.
• Assessment of poly(A) tail binding affinity and RNA helicase activity in the NE.

Main Results:

• Identified NE NTPase (stimulated by poly(A) tail), a poly(A)-recognizing mRNA carrier, NE protein kinase, and NE phosphatase.
• Discovered RNA helicase activity in the NE potentially involved in RNA transport.
• Demonstrated that double-stranded RNA structures, in addition to poly(A), can modulate RNA export.
• Observed a significant age-dependent decrease in mRNA release from nuclei, linked to impaired polyadenylation, hnRNA processing, nuclear matrix release, and translocation.

Conclusions:

• Key NE components regulating mRNA translocation have been identified.
• Aging impairs mRNA transport through decreased activity of NE NTPase, kinase, phosphatase, and reduced poly(A)-binding affinity.
• These age-related deficits contribute to reduced mRNA release and translocation, impacting gene expression.