scholarly journals A Direct Interaction of Axonin-1 with Ngcam-Related Cell Adhesion Molecule (Nrcam) Results in Guidance, but Not Growth of Commissural Axons

2000 ◽  
Vol 149 (4) ◽  
pp. 951-968 ◽  
Author(s):  
Dora Fitzli ◽  
Esther T. Stoeckli ◽  
Stefan Kunz ◽  
Kingsley Siribour ◽  
Christoph Rader ◽  
...  

An interaction of growth cone axonin-1 with the floor-plate NgCAM-related cell adhesion molecule (NrCAM) was shown to play a crucial role in commissural axon guidance across the midline of the spinal cord. We now provide evidence that axonin-1 mediates a guidance signal without promoting axon elongation. In an in vitro assay, commissural axons grew preferentially on stripes coated with a mixture of NrCAM and NgCAM. This preference was abolished in the presence of anti–axonin-1 antibodies without a decrease in neurite length. Consistent with these findings, commissural axons in vivo only fail to extend along the longitudinal axis when both NrCAM and NgCAM interactions, but not when axonin-1 and NrCAM or axonin-1 and NgCAM interactions, are perturbed. Thus, we conclude that axonin-1 is involved in guidance of commissural axons without promoting their growth.

2020 ◽  
Vol 295 (49) ◽  
pp. 16691-16699
Author(s):  
Razie Amraei ◽  
Tooba Alwani ◽  
Rachel Xi-Yeen Ho ◽  
Zahra Aryan ◽  
Shawn Wang ◽  
...  

Autophagy plays critical roles in the maintenance of endothelial cells in response to cellular stress caused by blood flow. There is growing evidence that both cell adhesion and cell detachment can modulate autophagy, but the mechanisms responsible for this regulation remain unclear. Immunoglobulin and proline-rich receptor-1 (IGPR-1) is a cell adhesion molecule that regulates angiogenesis and endothelial barrier function. In this study, using various biochemical and cellular assays, we demonstrate that IGPR-1 is activated by autophagy-inducing stimuli, such as amino acid starvation, nutrient deprivation, rapamycin, and lipopolysaccharide. Manipulating the IκB kinase β activity coupled with in vivo and in vitro kinase assays demonstrated that IκB kinase β is a key serine/threonine kinase activated by autophagy stimuli and that it catalyzes phosphorylation of IGPR-1 at Ser220. The subsequent activation of IGPR-1, in turn, stimulates phosphorylation of AMP-activated protein kinase, which leads to phosphorylation of the major pro-autophagy proteins ULK1 and Beclin-1 (BECN1), increased LC3-II levels, and accumulation of LC3 punctum. Thus, our data demonstrate that IGPR-1 is activated by autophagy-inducing stimuli and in response regulates autophagy, connecting cell adhesion to autophagy. These findings may have important significance for autophagy-driven pathologies such cardiovascular diseases and cancer and suggest that IGPR-1 may serve as a promising therapeutic target.


2001 ◽  
Vol 12 (9) ◽  
pp. 2699-2710 ◽  
Author(s):  
Evelyn B. Voura ◽  
Ravi A. Ramjeesingh ◽  
Anthony M.P. Montgomery ◽  
Chi-Hung Siu

Tumor metastasis involves many stage-specific adhesive interactions. The expression of several cell adhesion molecules, notably the integrin αvβ3, has been associated with the metastatic potential of tumor cells. In this study, we used a novel in vitro assay to examine the role of αvβ3 in the transmigration of melanoma cells through a monolayer of human lung microvascular endothelial cells. Confocal microscopy revealed the presence of the integrin αvβ3 on melanoma membrane protrusions and pseudopods penetrating the endothelial junction. αvβ3 was also enriched in heterotypic contacts between endothelial cells and melanoma cells. Transendothelial migration of melanoma cells was inhibited by either a cyclic Arg-Gly-Asp peptide or the anti-αvβ3monoclonal antibody LM609. Although both platelet endothelial cell adhesion molecule-1 and L1 are known to bind integrin αvβ3, only L1 serves as a potential ligand for αvβ3 during melanoma transendothelial migration. Also, polyclonal antibodies against L1 partially inhibited the transendothelial migration of melanoma cells. However, addition of both L1 and αvβ3 antibodies did not show additive effects, suggesting that they are components of the same adhesion system. Together, the data suggest that interactions between the integrin αvβ3 on melanoma cells and L1 on endothelial cells play an important role in the transendothelial migration of melanoma cells.


Angiogenesis ◽  
2004 ◽  
Vol 7 (3) ◽  
pp. 213-223 ◽  
Author(s):  
Heike Hall ◽  
Valentin Djonov ◽  
Martin Ehrbar ◽  
Matthias Hoechli ◽  
Jeffrey A. Hubbell

2021 ◽  
Author(s):  
Linzi Sun ◽  
Razie Amraei ◽  
Nader Rahimi

ABSTRACTThe cell adhesion molecule immunoglobulin and proline-rich receptor-1 (IGPR-1) regulates various critical cellular processes including, cell-cell adhesion, mechanosensing and autophagy. However, the molecular mechanisms governing IGPR-1 cell surface expression levels remains unknown. In the present study, we used an in vitro ubiquitination assay and identified ubiquitin E3 ligase NEDD4 and the ubiquitin conjugating enzyme UbcH6 involved in the ubiquitination of IGPR-1. In vitro GST-pulldown and in vivo co-immunoprecipitation assays demonstrated that NEDD4 binds to IGPR-1. Over-expression of wild-type NEDD4 downregulated IGPR-1 and deletion of WW domains (1-4) of NEDD4 revoked its effects on IGPR-1. Similarly, knockdown of NEDD4 increased IGPR-1 levels in A375 melanoma cells. Furthermore, deletion of 57 amino acids encompassing polyproline rich (PPR) motif on the C-terminus of IGPR-1 nullified the binding of NEDD4 with IGPR-1. Moreover, we demonstrate that NEDD4 promotes K48- and K63-dependent polyubiquitination of IGPR-1. The NEDD4-mediated polyubiquitination of IGPR-1 stimulated lysosomal degradation of IGPR-1 as the treatment of cells with the lysosomal inhibitors, bafilomycine and ammonium chloride increased IGPR-1 levels in the HEK-293 cells ectopically expressing IGPR-1 and in multiple human skin melanoma cell lines. Hence, these findings suggest that ubiquitin E3 ligase NEDD4 is a key regulator of IGPR-1 with a significant implication in the therapeutic targeting of IGPR-1.


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