Inside-Out Regulation of L1 Conformation, Integrin Binding, Proteolysis, and Concomitant Cell Migration

Abstract

The ectodomain structure and function of the neural cell adhesion molecule L1 is shown to be regulated by the intracellular phosphorylation of a novel threonine, T1172. In pancreatic cancer cells, T1172 exhibits steady-state saturated phosphorylation, an event regulated by CKII and PKC, and which further regulates cell migration.

Mitogen-activated protein kinase modulates ethanol inhibition of cell adhesion mediated by the L1 neural cell adhesion molecule

“…Phosphorylation of the L1-CD has also been shown to modify the structure and function of the L1-ECD. Chen et al (35) reported that phosphorylation of T1172 in the L1-CD altered L1 binding to integrins and masked or unmasked specific epitopes in the L1-ECD. Of note, L1 adhesion in the absence of ethanol was not altered by pharmacological inhibition of MEK1, ERK2 knockdown, or mutation of S1248 to leucine, although each of these interventions reduced or abolished ethanol inhibition of L1 adhesion.…”

“…The L1 cytoplasmic domain (L1-CD) is highly conserved across species and contains numerous sites for phosphorylation by casein kinase II, p90 ribosomal S6 kinase, extracellular signal-regulated kinase 2 (ERK2) [a member of the mitogen-activated protein kinase (MAPK) family], pp60c-src, chicken embryonic kinase 5, and potentially other kinases (32)(33)(34)(35). Phosphorylation of the L1-CD regulates the conformation and function of the extracellular domain (ECD) (36, 37), a phenomenon known as "inside-out" signaling and could conceivably modify the conformation of the alcohol binding pocket in the L1-ECD.…”

The Adhesion Molecule L1CAM as a Novel Therapeutic Target for Treatment of Pancreatic Cancer Patients?

“…On the other hand, numerous in vitro and in vivo studies provide compelling evidence for the role of L1CAM in cell migration of various tumor entities such as ovarian cancer (Arlt et al, 2006;Gast et al, 2005;Zecchini et al, 2008), colon cancer (Gavert et al, 2005;Gavert et al, 2011), melanoma (Meier et al, 2006), glioma (Yang et al, 2009;Yang et al, 2011), glioblastoma stem cells , breast cancer (Li & Galileo, 2010) and PDAC (Chen et al, 2010;Geismann et al, 2009). Cleavage of L1CAM seemed to be a prequisite for promoting the adhesion and migration of breast cancer cells (Li & Galileo, 2010) as well as for the motility of glioma (Yang et al, 2009), ovarian cancer (Mechtersheimer et al 2001) and colon cancer cells (Gavert et al, 2005).…”

Kinase Activity is Required for Growth Regulation but not Invasion Suppression by Syk Kinase in Pancreatic Adenocarcinoma Cells

“…Immunoblotting was performed essentially as described previously (Chen et al, 2010). Briefly, cells were lysed on the plate in NP40 lysis buffer (50mM Tris pH7.4, 150mM NaCl, 1% NP-40) containing Complete™ Protease Inhibitor Cocktail (Roche, Indianapolis, IN) supplemented with 10mM PMSF, 1mM NaF and 10mM Na 3 VO 4 .…”

“…FACS was performed on a FACScalibur (BD Biosciences, Bedford, MA) at the Moores UCSD Cancer Center Flow Cytometry Shared Resource as described previously (Chen et al, 2010). Cells were harvested with 0.1% trypsin/versene, inactivated with 0.1% soybean trypsin inhibitor and resuspended in FACS buffer (1mM MgCl 2 , 1mM CaCl 2 , 0.1% NaN 3 0.5% BSA in PBS pH 7.4) before sequential labelling with primary and FITC-conjugated secondary antibodies.…”