Inactivation of the proximal NPXY motif impairs early steps in LRP1 biosynthesis

Reekmans, Sara; Pflanzner, Thorsten; Gordts, Philip L.S.M.; Isbert, Simone; Zimmermann, Pascale; Annaert, Wim; Weggen, Sascha; Roebroek, Anton; Pietrzik, Claus U.

doi:10.1007/s00018-009-0171-7

Cited by 29 publications

(28 citation statements)

References 36 publications

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“…Based on these results we now investigated the surface expression of LRP1 and NMDA receptor subunits in primary cortical neurons derived of LRP1ΔNPxY2 mice and observed an increase in LRP1 surface expression compared to control neurons (Figure 1A, B). Since the knock-in in the NPxY2 motif overlaps with YxxL endocytosis motif of LRP1, which is also affected by the alanine substitution, the reduction in neuronal endocytosis of LRP1 mimics the reduced internalization of LRP1 recorded already in other cell types [2,4,28]. Most interestingly, we observed an additional increase in the surface expression of the NMDA receptor subunits NR1 and NR2B, but not of NR2A in primary LRP1ΔNPxY2 neurons (Figure 1A).…”

Section: Discussionsupporting

confidence: 57%

“…Previously it was shown that internalization of LRP1 is altered in mouse embryonic fibroblasts harboring a knock-in mutation in the distal NPxY motif of LRP1 [2,4,28]. Accordingly, we extended our analysis to primary cortical neurons (DIV14) derived from LRP1ΔNPxY2 mice or from wild type controls, employing the surface biotinylation technique.…”

Section: Resultsmentioning

confidence: 99%

“…The α-subunit contains four ligand binding domains for more than 30 ligands while the β-subunit contains two intracellular NPxY motifs [1]. Generation of cells from mice carrying a knock-in mutation in the NPxYxxL (NPxY2) sequence revealed a reduced internalization rate for LRP1 [2-4]. The NPxY2 motif has been shown to interact with the majority of known intracellular interaction partners of LRP1, many of which only bound the tyrosine phosphorylated form [5,6].…”

Section: Introductionmentioning

confidence: 99%

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LRP1 is critical for the surface distribution and internalization of the NR2B NMDA receptor subtype

Maier

Bednorz

Meister

et al. 2013

Mol Neurodegeneration

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BackgroundThe N-methyl-D-aspartate receptors are key mediators of excitatory transmission and are implicated in many forms of synaptic plasticity. These receptors are heterotetrameres consisting of two obligatory NR1 and two regulatory subunits, usually NR2A or NR2B. The NR2B subunits are abundant in the early postnatal brain, while the NR2A/NR2B ratio increases during early postnatal development. This shift is driven by NMDA receptor activity. A functional interplay of the Low Density Lipoprotein Receptor Related Protein 1 (LRP1) NMDA receptor has already been reported. Such abilities as interaction of LRP1 with NMDA receptor subunits or its important role in tPa-mediated NMDA receptor signaling were already demonstrated. Moreover, mice harboring a conditional neuronal knock-out mutation of the entire Lrp1 gene display NMDA-associated behavioral changes. However, the exact role of LRP1 on NMDA receptor function remains still elusive.ResultsTo provide a mechanistic explanation for such effects we investigated whether an inactivating knock-in mutation into the NPxY2 motif of LRP1 might influence the cell surface expression of LRP1 and NMDA receptors in primary cortical neurons. Here we demonstrate that a knock-in into the NPxY2 motif of LRP1 results in an increased surface expression of LRP1 and NR2B NMDA receptor subunit due to reduced endocytosis rates of LRP1 and the NR2B subunit in primary neurons derived from LRP1ΔNPxY2 animals. Furthermore, we demonstrate an altered phosphorylation pattern of S1480 and Y1472 in the NR2B subunit at the surface of LRP1ΔNPxY2 neurons, while the respective kinases Fyn and casein kinase II are not differently regulated compared with wild type controls. Performing co-immunoprecipitation experiments we demonstrate that binding of LRP1 to NR2B might be linked by PSD95, is phosphorylation dependent and this regulation mechanism is impaired in LRP1ΔNPxY2 neurons. Finally, we demonstrate hyperactivity and changes in spatial and reversal learning in LRP1ΔNPxY2 mice, confirming the mechanistic interaction in a physiological readout.ConclusionsIn summary, our data demonstrate that LRP1 plays a critical role in the regulation of NR2B expression at the cell surface and may provide a mechanistic explanation for the behavioral abnormalities detected in neuronal LRP1 knock-out animals reported earlier.

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Section: Discussionsupporting

confidence: 57%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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LRP1 is critical for the surface distribution and internalization of the NR2B NMDA receptor subtype

Maier

Bednorz

Meister

et al. 2013

Mol Neurodegeneration

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“…Western Blot analysis revealed a 2-fold reduction of LRP1 expression in PCN treated with Tat-Cre for 48 h compared to neurons incubated with the vehicle (Figure 7A). We assume that the incomplete reduction of LRP1 was due to its long half-life (24 h) (Reekmans et al, 2010). Interestingly, the sAPP dimer/APP dimer ratio of neurons with a partial Lrp1 knock-out showed a more than 2-fold increase in comparison to the buffer treated PCN (Figure 7B).…”

Section: Resultsmentioning

confidence: 99%

LRP1 Modulates APP Intraneuronal Transport and Processing in Its Monomeric and Dimeric State

Herr

Strecker

Storck

et al. 2017

Front. Mol. Neurosci.

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The low-density lipoprotein receptor-related protein 1, LRP1, interacts with APP and affects its processing. This is assumed to be mostly caused by the impact of LRP1 on APP endocytosis. More recently, also an interaction of APP and LRP1 early in the secretory pathway was reported whereat retention of LRP1 in the ER leads to decreased APP cell surface levels and in turn, to reduced Aβ secretion. Here, we extended the biochemical and immunocytochemical analyses by showing via live cell imaging analyses in primary neurons that LRP1 and APP are transported only partly in common (one third) but to a higher degree in distinct fast axonal transport vesicles. Interestingly, co-expression of LRP1 and APP caused a change of APP transport velocities, indicating that LRP1 recruits APP to a specific type of fast axonal transport vesicles. In contrast lowered levels of LRP1 facilitated APP transport. We further show that monomeric and dimeric APP exhibit similar transport characteristics and that both are affected by LRP1 in a similar way, by slowing down APP anterograde transport and increasing its endocytosis rate. In line with this, a knockout of LRP1 in CHO cells and in primary neurons caused an increase of monomeric and dimeric APP surface localization and in turn accelerated shedding by meprin β and ADAM10. Notably, a choroid plexus specific LRP1 knockout caused a much higher secretion of sAPP dimers into the cerebrospinal fluid compared to sAPP monomers. Together, our data show that LRP1 functions as a sorting receptor for APP, regulating its cell surface localization and thereby its processing by ADAM10 and meprin β, with the latter exhibiting a preference for APP in its dimeric state.

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“…LRP1 contains two NPxY motifs in its cytoplasmic tail. The proximal NPxY motif was shown to be essential for proper maturation of LRP1 along the secretory pathway, whereas the distal NPxY2 (NPx-YXXL) motif seems to be responsible for the internalization of LRP1 into endocytic vesicles (Li et al 2000;Reekmans et al 2010). LRP1 is abundantly present in the developing and adult brain.…”

Section: Lrp1 Function In App Metabolismmentioning

confidence: 98%

The role of lipoprotein receptors on the physiological function of APP

Wagner

Pietrzik

2011

Exp Brain Res

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In this review, we will primarily focus on the role of members of the low-density lipoprotein receptor (LDL-R) family that are involved in trafficking and processing of the amyloid precursor protein (APP). We will discuss the role of the LDL-receptor family members, low-density lipoprotein receptor-related protein 1 (LRP1), LRP1b, apolipoprotein E receptor 2, sortilin-related receptor (SorLA/LR11) and megalin/LRP2 on the physiological function of APP and its cellular localization. Additionally, we will focus on adaptor proteins that have been shown to influence the physiological function of LDL-R family members in combination with APP processing. The results in this review emphasize that the physiological function of APP cannot be explained by the focus on the APP protein alone but rather in combination with various direct or indirect interaction partners within the cellular environment.

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Inactivation of the proximal NPXY motif impairs early steps in LRP1 biosynthesis

Cited by 29 publications

References 36 publications

LRP1 is critical for the surface distribution and internalization of the NR2B NMDA receptor subtype

LRP1 is critical for the surface distribution and internalization of the NR2B NMDA receptor subtype

LRP1 Modulates APP Intraneuronal Transport and Processing in Its Monomeric and Dimeric State

The role of lipoprotein receptors on the physiological function of APP

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