A pathway involving HDAC5, cFLIP and caspases regulates expression of the splicing regulator polypyrimidine tract...

Area of Science:

• Molecular Biology
• Developmental Biology
• Cardiovascular Research

Background:

• Polypyrimidine tract binding protein (PTB) is crucial for pre-mRNA splicing, particularly in differentiating muscle.
• PTB protein levels decrease during heart development, independent of its transcript levels.
• Reduced histone deacetylase (HDAC) expression accompanies PTB reduction, suggesting a link.

Purpose of the Study:

• To investigate the regulatory pathway controlling PTB protein abundance during cardiac muscle development.
• To elucidate the roles of HDAC, cFLIP, and caspases in PTB regulation.
• To understand how PTB regulation impacts alternative splicing in the heart.

Main Methods:

• Utilizing HDAC5-deficient mice and myocyte cultures to study PTB regulation.
• Employing HDAC inhibition and cFLIP overexpression experiments.
• Analyzing PTB cleavage, fragmentation, and accumulation using proteasome inhibitors.
• Assessing changes in alternative splicing of TPM1, TPM2, and MEF2 genes.

Main Results:

• HDAC5 deficiency reduces cardiac PTB protein.
• HDAC inhibition in myocytes decreases cFLIP and promotes PTB cleavage by caspases.
• Cardiac PTB is elevated in caspase-deficient mice and protected by cFLIP.
• PTB cleavage leads to fragmentation and altered alternative splicing of key cardiac genes.

Conclusions:

• A novel pathway involving HDAC, cFLIP, and caspases regulates PTB disappearance during cardiac development.
• This pathway is essential for the switch to adult cardiac gene splicing patterns.
• The findings provide insights into the molecular mechanisms governing heart maturation and function.