Structural basis of a small molecule targeting RNA for a specific splicing correction

Area of Science:

• Molecular Biology
• Genetics
• Drug Discovery

Background:

• Spinal muscular atrophy (SMA) is a severe genetic disorder caused by low levels of survival motor neuron (SMN) protein.
• Enhancing SMN2 exon 7 inclusion is a therapeutic strategy for SMA.
• Splicing modifiers offer potential for SMA treatment by targeting SMN2 splicing.

Purpose of the Study:

• To elucidate the atomic mechanism by which splicing modifiers promote SMN2 exon 7 inclusion.
• To understand the drug's selective interaction with the SMN2 pre-mRNA.
• To characterize the structural basis of enhanced 5' splice site recognition.

Main Methods:

• Determining the solution structure of the RNA duplex at atomic resolution.
• Investigating the interaction between the splicing modifier and the SMN2 pre-mRNA.
• Analyzing the effect of the drug on U1 snRNP recognition of the 5' splice site.

Main Results:

• The splicing modifier selectively binds to and stabilizes a bulged adenine at the SMN2 exon 7 5' splice site.
• This stabilization converts the weak 5' splice site into a stronger one, promoting exon 7 inclusion.
• The drug acts as a specific splicing enhancer, working cooperatively with the cellular splicing machinery.

Conclusions:

• A novel mechanism for gene-specific alternative splicing correction, termed '5' splice site bulge repair', has been uncovered.
• Splicing modifiers can be designed to specifically target and correct aberrant splicing events.
• This provides a new avenue for developing targeted therapies for genetic disorders like SMA.