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Neuroprotective effects of calmodulin peptide 76-121aa: disruption of calmodulin binding to mutant huntingtin

Nichole L Dudek1, Ying Dai, Nancy A Muma

  • 1Department of Pharmacology and Experimental Therapeutics, Loyola University Chicago School of Medicine, Maywood, IL, USA.

Brain Pathology (Zurich, Switzerland)
|April 3, 2009
PubMed

Insights

A novel peptide targeting the interaction between calmodulin and mutant huntingtin protein reduced toxicity in Huntington's disease (HD) models. This specific disruption offers a potential new therapeutic strategy for HD by selectively inhibiting harmful protein modifications.

Area of Science:

  • Neuroscience
  • Molecular Biology
  • Genetics

Background:

  • Huntington's disease (HD) is a neurodegenerative disorder linked to mutant huntingtin protein with expanded polyglutamine tracts.
  • Abnormal protein-protein interactions, including increased association with calmodulin (CaM), are implicated in HD pathogenesis.
  • Previous studies showed a CaM-peptide (amino acids 76-121) reduced mutant huntingtin cytotoxicity and transglutaminase (TG)-modified huntingtin in HEK293 cells.

Purpose of the Study:

  • To investigate the therapeutic potential of a CaM-peptide in a cellular model of Huntington's disease.
  • To determine if CaM-peptide expression can reduce TG-modified huntingtin and cytotoxicity in neuronal cells.
  • To assess the selectivity of the CaM-peptide's effect on CaM-dependent interactions.

Main Methods:

  • Adeno-associated virus (AAV)-mediated expression of CaM-peptide in differentiated SH-SY5Y neuroblastoma cells stably expressing mutant huntingtin.
  • Quantification of TG-modified huntingtin and assessment of cytotoxicity.
  • In vitro binding assays using recombinant huntingtin exon 1 (htt-exon1-44Q), CaM-agarose, and CaM-peptide to evaluate interaction specificity.

Main Results:

  • AAV-mediated CaM-peptide expression significantly decreased TG-modified huntingtin and attenuated cytotoxicity in HD model cells.
  • The CaM-peptide selectively disrupted the CaM-huntingtin interaction without altering total TG activity or CaM kinase II activity.
  • In vitro assays confirmed that CaM-peptide specifically inhibited htt-exon1-44Q binding to CaM, but not CaM binding to calcineurin.

Conclusions:

  • Calmodulin (CaM) plays a regulatory role in TG-catalyzed modifications of mutant huntingtin.
  • Specific and selective disruption of the CaM-huntingtin interaction using CaM-peptide is a promising therapeutic target for Huntington's disease.
  • This approach offers a targeted strategy to mitigate HD-associated neurotoxicity by interfering with key pathological interactions.

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