A novel receptor function for the heat shock protein Grp78: silencing of Grp78 gene expression attenuates alpha2M*-induced signalling.

Published

Journal Article

The activated proteinase inhibitor alpha2-macroglobulin (alpha2M*) binds to two receptors, the low density lipoprotein receptor-related protein (LRP-1) and the alpha2M* signalling receptor (alpha2MSR). Silencing LRP-1 gene expression in macrophages by RNA interference does not block alpha2M* activation of signalling cascades. We now demonstrate that transfection of macrophages with a double-stranded RNA homologous in sequence to the Grp78 gene markedly decreased induction of inositol 1,4,5-trisphosphate (IP3) and subsequent IP3-dependent elevation of [Ca2+]i induced by alpha2M*. Concomitantly, alpha2M*-induced increase in [3H]thymidine uptake was abolished in these transfected cells. Insulin treatment significantly upregulates alpha2MSR and it also caused a marked increase in Grp78 expression which could be blocked by RNA interference. alpha2M* treatment of cells activates the Ras- and PI 3-kinase-dependent signalling pathways. Suppressing Grp78 expression leads to the loss of these activation events in transfected macrophages. We thus conclude that Grp78 is the alpha2M* signalling receptor.

Full Text

Duke Authors

Cited Authors

  • Misra, UK; Gonzalez-Gronow, M; Gawdi, G; Wang, F; Pizzo, SV

Published Date

  • August 2004

Published In

Volume / Issue

  • 16 / 8

Start / End Page

  • 929 - 938

PubMed ID

  • 15157672

Pubmed Central ID

  • 15157672

International Standard Serial Number (ISSN)

  • 0898-6568

Digital Object Identifier (DOI)

  • 10.1016/j.cellsig.2004.01.003

Language

  • eng

Conference Location

  • England