scholarly journals ALCAM-EGFR Interaction Regulates Myelomagenesis

Author(s):  
Hongmei Luo ◽  
Dan Zhang ◽  
Fangfang Wang ◽  
Qiang Wang ◽  
Yu Wu ◽  
...  

Multiple myeloma, a plasma cell malignancy in the bone marrow, remains largely incurable with currently available therapeutics. In this study, we discovered that the activated-leukocyte-cell-adhesion-molecule (ALCAM) interacted with epidermal growth factor receptor (EGFR), and regulated myelomagenesis. ALCAM was a negative regulator of myeloma clonogenicity. ALCAM expression was positively correlated with patients' survival. ALCAM-knockdown myeloma cells displayed enhanced colony formation in the presence of bone marrow stromal cells (BMSCs). BMSCs supported myeloma colony formation by secreted epidermal growth factor (EGF), which bound with its receptor (EGFR) on myeloma cells and activated Mek/Erk cell signaling, PI3K/Akt cell signaling and hedgehog pathway. ALCAM could also bind with EGFR, block EGF from binding to EGFR, and abolish EGFR-initiated cell signaling. Hence, our study identifies ALCAM as a novel negative regulator of myeloma pathogenesis.

2009 ◽  
Vol 51 (6) ◽  
pp. 1010-1020 ◽  
Author(s):  
Ana Pardo-Saganta ◽  
Maria Ujue Latasa ◽  
Josefa Castillo ◽  
Laura Alvarez-Asiain ◽  
María J. Perugorría ◽  
...  

2008 ◽  
Vol 19 (3) ◽  
pp. 1252-1260 ◽  
Author(s):  
Elsa-Noah N'Diaye ◽  
Aylin C. Hanyaloglu ◽  
Kimberly K. Kajihara ◽  
Manojkumar A. Puthenveedu ◽  
Ping Wu ◽  
...  

The activity of many signaling receptors is regulated by their endocytosis via clathrin-coated pits (CCPs). For G protein-coupled receptors (GPCRs), recruitment of the adaptor protein arrestin to activated receptors is thought to be sufficient to drive GPCR clustering in CCPs and subsequent endocytosis. We have identified an unprecedented role for the ubiquitin-like protein PLIC-2 as a negative regulator of GPCR endocytosis. Protein Linking IAP to Cytoskeleton (PLIC)-2 overexpression delayed ligand-induced endocytosis of two GPCRs: the V2 vasopressin receptor and β-2 adrenergic receptor, without affecting endocytosis of the transferrin or epidermal growth factor receptor. The closely related isoform PLIC-1 did not affect receptor endocytosis. PLIC-2 specifically inhibited GPCR concentration in CCPs, without affecting membrane recruitment of arrestin-3 to activated receptors or its cellular levels. Depletion of cellular PLIC-2 accelerated GPCR endocytosis, confirming its regulatory function at endogenous levels. The ubiquitin-like domain of PLIC-2, a ligand for ubiquitin-interacting motifs (UIMs), was required for endocytic inhibition. Interestingly, the UIM-containing endocytic adaptors epidermal growth factor receptor protein substrate 15 and Epsin exhibited preferential binding to PLIC-2 over PLIC-1. This differential interaction may underlie PLIC-2 specific effect on GPCR endocytosis. Identification of a negative regulator of GPCR clustering reveals a new function of ubiquitin-like proteins and highlights a cellular requirement for exquisite regulation of receptor dynamics.


2005 ◽  
Vol 280 (43) ◽  
pp. 36185-36194 ◽  
Author(s):  
Fumi Mikami ◽  
He Gu ◽  
Hirofumi Jono ◽  
Ali Andalibi ◽  
Hirofumi Kai ◽  
...  

Epidermal growth factor receptor (EGFR) has been shown to play important roles in regulating diverse biological processes, including cell growth, differentiation, apoptosis, adhesion, and migration. Its role in regulating human Toll-like receptors (TLRs), key host defense receptors that recognize invading bacterial pathogens, however, remains unknown. Here we show for the first time that EGFR acts as a negative regulator for TLR2 induction by the bacterium nontypeable Haemophilus influenzae (NTHi) in vitro and in vivo. The negative regulation of TLR2 induction by EGFR is mediated via an Src-MKK3/6-p38 α/β MAP kinase-dependent mechanism. Moreover, direct activation of EGFR signaling by the bacterium NTHi-derived EGF-like factor appears to be responsible for triggering the downstream Src-MKK3/6-p38 MAPK signaling, which in turn leads to the negative regulation of TLR2 induction. Finally, exogenous EGF increases NTHi invasion of host epithelial cells, thereby demonstrating the biological significance of TLR2 regulation by EGFR signaling. The evidence we provided in the present study may suggest a novel strategy utilized by bacteria to attenuate host defensive and immune response by negatively regulating the expression of host defense receptor TLR2. These studies may bring new insight for fully understanding the important role of EGFR signaling in regulating host defense and immune response by tightly controlling TLR2 induction during bacterial infections.


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