A designed recombinant fusion protein for targeted delivery of siRNA to the mouse brain
Mohamed Mohamed Haroon, Ghulam Hassan Dar, Durga Jeyalakshmi, Uthra Venkatraman, Kamal Saba, Nandini Rangaraj, Anant Bahadur Patel, Vijaya Gopal
Journal of Controlled Release
RNA interference represents a novel therapeutic approach to modulate several neurodegenerative disease-related genes. However, exogenous delivery of siRNA restricts their transport into different tissues and specifically into the brain mainly due to its large size and the presence of the blood–brain barrier (BBB). To overcome these challenges, we developed here a strategy wherein a peptide known to target specific gangliosides was fused to a double-stranded RNA binding protein to deliver siRNA to the brain parenchyma. The designed fusion protein designated as TARBP-BTP consists of a double-stranded RNA-binding domain (dsRBD) of human Trans Activation response element (TAR) RNA Binding Protein (TARBP2) fused to a brain targeting peptide that binds to monosialoganglioside GM1. Conformation-specific binding of TARBP2 domain to siRNA led to the formation of homogenous serum-stable complex with targeting potential. Further, uptake of the complex in Neuro-2a, IMR32 and HepG2 cells analyzed by confocal microscopy and fluorescence activated cell sorting, revealed selective requirement of GM1 for entry. Remarkably, systemic delivery of the fluorescently labeled complex (TARBP-BTP:siRNA) in ΑβPP-PS1 mouse model of Alzheimer's disease (AD) led to distinctive localization in the cerebral hemisphere. Further, the delivery of siRNA mediated by TARBP-BTP led to significant knockdown of BACE1 in the brain, in both ΑβPP-PS1 mice and wild type C57BL/6. The study establishes the growing importance of fusion proteins in delivering therapeutic siRNA to brain tissues.
Circular dichroism, Secondary structure, Pharmaceutical, Biochemistry