’15 PREVENTION AND TREATMENT OF NEURODEGENERATIVE DISEASES THROUGH AUTOPHAGY ACTIVITY MEDIATED BY LIGAND OR ARGINYLATED BIP BINDING TO P62 ZZ DOMAIN(KR, WO)
The drug action mechanisms and core techniques of the present invention are summarized in figure 1.
Specifically, malignant denatured proteins, such as mutant Huntingtin protein or α-synuclein,
stick together to grow into oligomer aggregates (①, ②), fibrillar aggregates (③), and ultimately inclusion bodies (④).
Young neuronal cells produce a large quantity of Nt-Arg through N-terminal arginylation (⑤) of endoplasmic reticulum chaperones,
such as BiP, and thereafter, arginylated BiP (R-BiP) comes into the cytoplasm and binds with denatured proteins (⑥).
Nt-Arg of R-BiP, as a ligand, binds with the ZZ domain of p62 (⑦) to induce the structural activation of p62 (⑧) while the ordinarily closed inactive form
of p62 is changed with an open form thereof, and thus PB1 and LC3-binding domains are exposed.
On the basis of oligomerization (⑨) by the PB1 domain, p62 binds with the denatured protein aggregates to be concentrated to autophagically degradable aggregates, that is, p62 bodies (⑩).
Thereafter, p62 completes autophagy targeting (⑪) and lysosomal proteolysis through binding with LC3 protruding on the autophagosomal membranes.
In young neuronal cells, the autophagic proteolysis occurring through steps ⑤-⑪ is strong, and thus the cytotoxic protein aggregates (①-⑤) do not
accumulate, but in aged neuronal cells, the autophagic proteolysis occurring through steps ⑤-⑪ is weakened,
and thus the protein aggregates (①-⑤) accumulate, resulting in a vicious cycle.
The present invention attempts to effectively remove Huntingtin and α-synuclein protein aggregates and
the like by artificially activating p62 using low-mass ligands of the p62 ZZ domain (⑫, ⑬).
Specifically, p62 binding the ligands through step ⑫ promotes p62-R-BiP-denatured protein oligomerization (⑨) and autophagy aggregate formation (⑩).
In addition, the ligand-62 conjugates step ⑬ act as autophagy activators (⑭), to promote LC3 synthesis,
the conversion of LC3-I into LC3-II, and the like, thereby promoting the formation of autophagosomes (⑮).