Presenilin/γ-Secretase-mediated Cleavage Regulates Association of Leukocyte-Common Antigen-related (LAR) Receptor Tyrosine Phosphatase with β-Catenin

Abstract

Leukocyte-common antigen-related (LAR) receptor tyrosine phosphatase regulates cell adhesion and formation of functional synapses and neuronal networks. Here we report that LAR is sequentially cleaved by ␣-and presenilin (PS)/␥-secretases, which also affect signaling and/or degradation of type-I membrane proteins including the Alzheimer disease-related ␤-amyloid precursor protein. Similar to the previously characterized PS/␥-secretase substrates, inhibition of ␥-secretase activity resulted in elevated LAR C-terminal fragment (LAR-CTF) levels in stably LAR-overexpressing Chinese hamster ovary (CHO) cells, human neuroglioma cells, and mouse cortical neurons endogenously expressing LAR. Furthermore, LAR-CTF levels increased in cells lacking functional PS, indicating that ␥-secretase-mediated cleavage of LAR was PS-dependent. Inhibition of ␣-secretase activity by TAPI-1 treatment blocked LAR-CTF accumulation, demonstrating that prior ectodomain shedding was prerequisite for PS/␥-secretase-mediated cleavage of LAR. Moreover, we identified the product of PS/␥-secretase cleavage, LAR intracellular domain (LICD), both in vitro and in cells overexpressing full-length (FL) LAR or LAR-CTFs. LAR localizes to cadherin-␤-catenin-based cellular junctions. Assembly and disassembly of these junctions are regulated by tyrosine phosphorylation. We found that endogenous tyrosine-phosphorylated ␤-catenin coimmunoprecipitated with LAR in CHO cells. However, when PS/␥-secretase activity was inhibited, the association between LAR and ␤-catenin significantly diminished. In addition to cell adhesion, ␤-catenin is involved in transcriptional regulation. We observed that LICD significantly decreased transcription of cyclin D1, one of the ␤-catenin target genes. Thus, our results show that PS/␥-secretase-mediated cleavage of LAR controls LAR-␤-catenin interaction, suggesting an essential role for PS/␥-secretase in the regulation of LAR signaling. Presenilin (PS)2 /␥-secretase is a high molecular weight enzymatic complex composed of PS1 or PS2, nicastrin, Aph-1, and Pen-2 (1-5). PS/␥-secretase plays a key role in the pathogenesis of Alzheimer disease (AD) by cleaving ␤-amyloid precursor protein (APP) by regulated intramembraneous processing (RIP) at two adjacent sites (6 -8). Following ectodomain shedding of APP, the ␥-cleavage generates the A␤-peptide, the major constituent of amyloid plaques in AD brain, and a small p3 fragment. The product of the ⑀-cleavage is the APP intracellular domain (AICD) (9 -11). APP ectodomain shedding is mediated by either ␣-secretases of the ADAM family metalloproteases (12, 13) or BACE (␤-site APP cleaving enzyme) (14 -17), producing membrane-bound APP C-terminal fragments (CTFs). In addition to APP, other type-I membrane proteins are known to undergo PS/␥-secretase-mediated RIP (18). Among these are Notch (8), cadherins (19), nectin-1␣ (20), and voltagegated sodium channel ␤2-subunit (21, 22). Similar to APP, these proteins undergo ectodomain shedding prior to ␥-secretase-mediated cleavage and release intrace...

Transmembrane Proteins UNC-40/DCC, PTP-3/LAR, and MIG-21 Control Anterior–Posterior Neuroblast Migration with Left–Right Functional Asymmetry in Caenorhabditis elegans

“…It is also possible that the extracellular domain of PTP-3 is cleaved and serves as a diffusible signaling molecule. Indeed, the extracellular domain of mammalian LAR is shed in response to calcium ionophores, phorbol esters, and EGF receptor activity mediated by the alpha-secretase matrix metalloprotease ADAM-17/TACE (Aicher et al 1997;Ruhe et al 2006;Haapasalo et al 2007). These studies show that ectodomain shedding is important for the regulation of the intracellular domain of LAR (an autonomous function), but it is possible that the cleaved ectodomain plays a nonautonomous signaling role.…”

Inactivation of LAR family phosphatase genesPtprsandPtprfcauses craniofacial malformations resembling Pierre-Robin sequence

“…Hendriks et al, 2013). LAR family phosphatases have been implicated in several key embryonic signaling pathways, including those involved in the negative regulation of growth factor receptors such as EGFR, RET and MET, and potentially modulate canonical Wnt/β-catenin signaling (Kypta et al, 1996;Müller et al, 1999;Tisi et al, 2000;Wang et al, 2000; Ensslen-Craig and BradyKalnay, 2004;Machide et al, 2006;Haapasalo et al, 2007;Uetani et al, 2009;Zheng et al, 2011). Although LAR family phosphatases are expressed in several embryonic and adult tissues (Schaapveld et al, 1998), mice mutant for single family members generally survive to adulthood, reflecting a functional redundancy within the family (Schaapveld et al, 1997; Elchebly et al, 1999;Wallace et al, 1999;Uetani et al, 2000;Thompson et al, 2003;Wang et al, 2011).…”

The cytoplasmic tail of CD45 is released from activated phagocytes and can act as an inhibitory messenger for T cells

“…[21][22][23][24][25] A growing number of PTPs are now known to undergo posttranslational proteolytic processing. [26][27][28][29][30] For instance, the CD45-related receptor-type PTP (RPTP) leukocyte-common antigenrelated (LAR) has been reported to be cleaved by the presenilin/␥-secretase complex. 27 Cleavage of the intracellular parts of type I cell surface receptors by presenilin/␥-secretase is typically executed after the receptors have undergone ectodomain shedding.…”

“…[26][27][28][29][30] For instance, the CD45-related receptor-type PTP (RPTP) leukocyte-common antigenrelated (LAR) has been reported to be cleaved by the presenilin/␥-secretase complex. 27 Cleavage of the intracellular parts of type I cell surface receptors by presenilin/␥-secretase is typically executed after the receptors have undergone ectodomain shedding. 26,27,29,30 It is noteworthy that proteolysis by the presenilin/␥-secretase is not only a simple degradation process but frequently generates fragments of cell surface receptors with novel biologic functions.…”

“…27 Cleavage of the intracellular parts of type I cell surface receptors by presenilin/␥-secretase is typically executed after the receptors have undergone ectodomain shedding. 26,27,29,30 It is noteworthy that proteolysis by the presenilin/␥-secretase is not only a simple degradation process but frequently generates fragments of cell surface receptors with novel biologic functions. 29,30 Whether CD45 is proteolytically processed in leukocytes has not yet been investigated.…”