title: The functional role of the second NPXY motif of the LRP1 beta-chain in tissue-type plasminogen activator-mediated activation of N-methyl-D-aspartate receptors.
abstract: The low density lipoprotein receptor-related protein 1 (LRP1) emerges to play fundamental roles in cellular signaling pathways in the brain. One of its prominent ligands is the serine proteinase tissue-type plasminogen activator (tPA), which has been shown to act as a key activator of neuronal mitogen-activated protein kinase pathways via the N-methyl-D-aspartate (NMDA) receptor. However, here we set out to examine whether LRP1 and the NMDA receptor might eventually act in a combined fashion to mediate tPA downstream signaling. By blocking tPA from binding to LRP1 using the receptor-associated protein, we were able to completely inhibit NMDA receptor activation. Additionally, inhibition of NMDA receptor calcium influx with MK-801 resulted in dramatic reduction of tPA-mediated downstream signaling. This indicates a functional interaction between the two receptors, since both experimental approaches resulted in strongly reduced calcium influx and Erk1/2 phosphorylation. Additionally, we were able to inhibit Erk1/2 activation by competing for the LRP1 C-terminal binding motif with a truncated PSD95 construct resembling its PDZ III domain. Furthermore, we identified the distal NPXY amino acid motif in the C terminus of LRP1 as the crucial element for LRP1-NMDA receptor interaction via the adaptor protein PSD95. These results provide new insights into the mechanism of a tPA-induced, LRP1-mediated gating mechanism for NMDA receptors.
authors.affiliation: Institute of Physiological Chemistry and Pathobiochemistry, Molecular Neurodegeneration and Institute of Physiology, Johannes-Gutenberg-University Mainz, D-55099 Mainz, Germany.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Martin
authors.forename: Christoph
authors.initials: C
authors.lastname: Kuhlmann
authors.forename: Svenja
authors.initials: S
authors.lastname: Trossbach
authors.forename: Sebastian
authors.initials: S
authors.lastname: Jaeger
authors.forename: Elaine
authors.initials: E
authors.lastname: Waldron
authors.forename: Anton
authors.initials: A
authors.lastname: Roebroek
authors.forename: Heiko J
authors.initials: HJ
authors.lastname: Luhmann
authors.forename: Alexander
authors.initials: A
authors.lastname: Laatsch
authors.forename: Sascha
authors.initials: S
authors.lastname: Weggen
authors.forename: Volkmar
authors.initials: V
authors.lastname: Lessmann
authors.forename: Claus U
authors.initials: CU
authors.lastname: Pietrzik
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D000076122:Disks Large Homolog 4 Protein; D004789:Enzyme Activation / Q000187:drug effects; D051528:Guanylate Kinases; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D026503:Low Density Lipoprotein Receptor-Related Protein-1 / Q000037:antagonists & inhibitors / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000201:enzymology; D010766:Phosphorylation / Q000187:drug effects; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D017433:Protein Structure, Secondary; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020239:Receptor Cross-Talk / Q000187:drug effects; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013329:Structure-Activity Relationship; D010959:Tissue Plasminogen Activator / Q000494:pharmacology*
chemical_list: D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D016194:Receptors, N-Methyl-D-Aspartate; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D051528:Guanylate Kinases; D010959:Tissue Plasminogen Activator; D002118:Calcium