Essential role for autophagy protein VMP1 in maintaining neuronal homeostasis and preventing axonal degeneration

Cell Death Dis. 2021 Jan 22;12(1):116. doi: 10.1038/s41419-021-03412-5.

Abstract

Vacuole membrane protein 1 (VMP1), the endoplasmic reticulum (ER)-localized autophagy protein, plays a key role during the autophagy process in mammalian cells. To study the impact of VMP1-deficiency on midbrain dopaminergic (mDAergic) neurons, we selectively deleted VMP1 in the mDAergic neurons of VMP1fl/fl/DATCreERT2 bigenic mice using a tamoxifen-inducible CreERT2/loxp gene targeting system. The VMP1fl/fl/DATCreERT2 mice developed progressive motor deficits, concomitant with a profound loss of mDAergic neurons in the substantia nigra pars compacta (SNc) and a high presynaptic accumulation of α-synuclein (α-syn) in the enlarged terminals. Mechanistic studies showed that VMP1 deficiency in the mDAergic neurons led to the increased number of microtubule-associated protein 1 light chain 3-labeled (LC3) puncta and the accumulation of sequestosome 1/p62 aggregates in the SNc neurons, suggesting the impairment of autophagic flux in these neurons. Furthermore, VMP1 deficiency resulted in multiple cellular abnormalities, including large vacuolar-like structures (LVSs), damaged mitochondria, swollen ER, and the accumulation of ubiquitin+ aggregates. Together, our studies reveal a previously unknown role of VMP1 in modulating neuronal survival and maintaining axonal homeostasis, which suggests that VMP1 deficiency might contribute to mDAergic neurodegeneration via the autophagy pathway.

Publication types

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

MeSH terms

  • Animals
  • Autophagy
  • Axons / pathology*
  • Homeostasis
  • Membrane Proteins / pharmacology
  • Membrane Proteins / therapeutic use*
  • Mice
  • Nerve Degeneration / pathology
  • Nerve Degeneration / prevention & control*

Substances

  • Membrane Proteins
  • VMP1 protein, mouse