Activated α2-Macroglobulin Regulates LRP1 Levels at the Plasma Membrane through the Activation of a Rab10-dependent Exocytic Pathway in Retinal Müller Glial Cells

Sci Rep. 2019 Sep 13;9(1):13234. doi: 10.1038/s41598-019-49072-6.

Abstract

Activated α2-macroglobulin (α2M*) and its receptor, low-density lipoprotein receptor-related protein 1 (LRP1), have been linked to proliferative retinal diseases. In Müller glial cells (MGCs), the α2M*/LRP1 interaction induces cell signaling, cell migration, and extracellular matrix remodeling, processes closely associated with proliferative disorders. However, the mechanism whereby α2M* and LRP1 participate in the aforementioned pathologies remains incompletely elucidated. Here, we investigate whether α2M* regulates both the intracellular distribution and sorting of LRP1 to the plasma membrane (PM) and how this regulation is involved in the cell migration of MGCs. Using a human Müller glial-derived cell line, MIO-M1, we demonstrate that the α2M*/LRP1 complex is internalized and rapidly reaches early endosomes. Afterward, α2M* is routed to degradative compartments, while LRP1 is accumulated at the PM through a Rab10-dependent exocytic pathway regulated by PI3K/Akt. Interestingly, Rab10 knockdown reduces both LRP1 accumulation at the PM and cell migration of MIO-M1 cells induced by α2M*. Given the importance of MGCs in the maintenance of retinal homeostasis, unravelling this molecular mechanism can potentially provide new therapeutic targets for the treatment of proliferative retinopathies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Membrane / metabolism*
  • Cell Movement
  • Cells, Cultured
  • Ependymoglial Cells / cytology
  • Ependymoglial Cells / metabolism*
  • Exocytosis*
  • Humans
  • Low Density Lipoprotein Receptor-Related Protein-1 / metabolism*
  • Protein Transport
  • Signal Transduction
  • alpha-Macroglobulins / metabolism*
  • rab GTP-Binding Proteins / metabolism*

Substances

  • LRP1 protein, human
  • Low Density Lipoprotein Receptor-Related Protein-1
  • alpha-Macroglobulins
  • Rab10 protein, human
  • rab GTP-Binding Proteins