Structural aspects of HDAC8 mechanism and dysfunction in Cornelia de Lange syndrome spectrum disorders

Area of Science:

• Biochemistry
• Genetics
• Molecular Biology

Background:

• Cornelia de Lange Syndrome (CdLS) is a genetic disorder with diverse symptoms, including developmental delays and physical abnormalities.
• CdLS is often caused by mutations in genes related to the cohesin complex, a crucial regulator of gene expression and DNA repair.
• HDAC8, a zinc-dependent hydrolase, plays a key role in cohesin regulation by deacetylating SMC3, a process vital for cell cycle progression.

Purpose of the Study:

• To investigate the impact of missense mutations in the HDAC8 gene, identified in CdLS patients, on its catalytic activity and stability.
• To explore potential therapeutic strategies by assessing the efficacy of chemical activators in restoring HDAC8 function.

Main Methods:

• Enzymological assays to measure the catalytic activity of wild-type and mutant HDAC8 proteins.
• Biophysical techniques to evaluate protein stability and structural changes induced by mutations.
• Structural studies to elucidate the molecular mechanisms underlying compromised enzyme function.

Main Results:

• 23 missense mutations in HDAC8 found in CdLS patients were analyzed.
• Most mutations resulted in structural alterations affecting substrate binding and catalytic efficiency.
• Several mutations significantly reduced the thermostability of the HDAC8 protein.
• An N-acylthiourea activator partially or fully restored catalytic activity in many HDAC8 mutants.

Conclusions:

• Mutations in HDAC8 disrupt its crucial role in cohesin biology, contributing to CdLS phenotypes.
• Chemical rescue using specific activators presents a promising therapeutic avenue for CdLS patients with HDAC8 mutations.
• Further research into HDAC8 activators could lead to novel treatments for cohesinopathies.