The design and delivery of a PKA inhibitory polypeptide to treat SCA1

Authors

  • Scoty M. Hearst,

    1. Department of Neurology, University of Mississippi Medical Center, Jackson, Mississippi, USA
    2. Department of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi, USA
    Search for more papers by this author
  • Qingmei Shao,

    1. Department of Neurology, University of Mississippi Medical Center, Jackson, Mississippi, USA
    Search for more papers by this author
  • Mariper Lopez,

    1. Department of Neurology, University of Mississippi Medical Center, Jackson, Mississippi, USA
    Search for more papers by this author
  • Drazen Raucher,

    1. Department of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi, USA
    Search for more papers by this author
  • Parminder J. S. Vig

    Corresponding author
    1. Department of Neurology, University of Mississippi Medical Center, Jackson, Mississippi, USA
    2. Department of Biochemistry, University of Mississippi Medical Center, Jackson, Mississippi, USA
    • Address correspondence and reprint requests to Parminder J. S. Vig, Department of Neurology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA. E-mail: pvig@umc.edu

    Search for more papers by this author

Abstract

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.

image

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.

Ancillary