The design and delivery of a PKA inhibitory polypeptide to treat SCA1
Article first published online: 23 JUN 2014
© 2014 International Society for Neurochemistry
Journal of Neurochemistry
Volume 131, Issue 1, pages 101–114, October 2014
How to Cite
J. Neurochem. (2014) 131, 101–114.
- Issue published online: 24 SEP 2014
- Article first published online: 23 JUN 2014
- Accepted manuscript online: 5 JUN 2014 10:24AM EST
- Manuscript Accepted: 2 JUN 2014
- Manuscript Revised: 13 MAY 2014
- Manuscript Received: 5 DEC 2013
- National Institutes of Health
- ataxin-1 phosphorylation;
- intranasal peptide delivery;
- PKA inhibitory peptide;
- Purkinje cell;
- spinocerebellar ataxia-1
Spinocerebellar ataxia-1 (SCA1) is a neurodegenerative disease that primarily targets Purkinje cells (PCs) of the cerebellum. The exact mechanism of PC degeneration is unknown, however, it is widely believed that mutant ataxin-1 becomes toxic because of the phosphorylation of its serine 776 (S776) residue by cAMP-dependent protein kinase A (PKA). Therefore, to directly modulate mutant ATXN1 S776 phosphorylation and aggregation, we designed a therapeutic polypeptide to inhibit PKA. This polypeptide comprised of a thermally responsive elastin-like peptide (ELP) carrier, which increases peptide half-life, a PKA inhibitory peptide (PKI), and a cell-penetrating peptide (Synb1). We observed that our therapeutic polypeptide, Synb1-ELP-PKI, inhibited PKA activity at concentrations similar to the PKI peptide. Additionally, Synb1-ELP-PKI significantly suppressed mutant ATXN1 S776 phosphorylation and intranuclear inclusion formation in cell culture. Further, Synb1-ELP-PKI treatment improved SCA1 PC morphology in cerebellar slice cultures. Furthermore, the Synb1-ELP peptide carrier crossed the blood–brain barrier and localized to the cerebellum via the i.p. or intranasal route. Here, we show the intranasal delivery of ELP-based peptides to the brain as a novel delivery strategy. We also demonstrate that our therapeutic polypeptide has a great potential to target the neurotoxic S776 phosphorylation pathway in the SCA1 disease.
Protein kinase A (PKA) phosphorylates mutant ataxin-1 and makes it resistant to degradation. We designed a PKA inhibitory polypeptide. Our polypeptide comprised a thermally responsive elastin-like peptide (ELP) carrier, a PKA inhibitory peptide (PKI) and a cell-penetrating peptide (Synb1). Synb1-ELP-PKI, inhibited PKA activity in various in vitro models. The polypeptide crossed the blood–brain barrier when administered intraperitoneally or intranasally. We demonstrate that our polypeptide is a potential candidate for Spinocerebellar ataxia-1 (SCA1) therapy.