Targeted manipulation of the sortilin-progranulin axis rescues progranulin haploinsufficiency

Hum Mol Genet. 2014 Mar 15;23(6):1467-78. doi: 10.1093/hmg/ddt534. Epub 2013 Oct 26.

Abstract

Progranulin (GRN) mutations causing haploinsufficiency are a major cause of frontotemporal lobar degeneration (FTLD-TDP). Recent discoveries demonstrating sortilin (SORT1) is a neuronal receptor for PGRN endocytosis and a determinant of plasma PGRN levels portend the development of enhancers targeting the SORT1-PGRN axis. We demonstrate the preclinical efficacy of several approaches through which impairing PGRN's interaction with SORT1 restores extracellular PGRN levels. Our report is the first to demonstrate the efficacy of enhancing PGRN levels in iPSC neurons derived from frontotemporal dementia (FTD) patients with PGRN deficiency. We validate a small molecule preferentially increases extracellular PGRN by reducing SORT1 levels in various mammalian cell lines and patient-derived iPSC neurons and lymphocytes. We further demonstrate that SORT1 antagonists and a small-molecule binder of PGRN₅₈₈₋₅₉₃, residues critical for PGRN-SORT1 binding, inhibit SORT1-mediated PGRN endocytosis. Collectively, our data demonstrate that the SORT1-PGRN axis is a viable target for PGRN-based therapy, particularly in FTD-GRN patients.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Vesicular Transport / genetics*
  • Adaptor Proteins, Vesicular Transport / metabolism
  • Cell Line, Tumor
  • Endocytosis / drug effects*
  • Frontotemporal Dementia / genetics*
  • Frontotemporal Dementia / pathology
  • Genetic Variation
  • HEK293 Cells
  • Haploinsufficiency
  • Humans
  • Induced Pluripotent Stem Cells / metabolism*
  • Intercellular Signaling Peptides and Proteins / genetics
  • Intercellular Signaling Peptides and Proteins / metabolism*
  • Lymphocytes / metabolism
  • Progranulins
  • Pyridines / pharmacology*
  • Reproducibility of Results

Substances

  • Adaptor Proteins, Vesicular Transport
  • GRN protein, human
  • Intercellular Signaling Peptides and Proteins
  • Progranulins
  • Pyridines
  • 6-methyl-2-(phenylethynyl)pyridine
  • sortilin