AQP1-Driven Migration Is Independent of Other Known Adverse Factors but Requires a Hypoxic Undifferentiated Cell Profile in Neuroblastoma

Neuroblastoma is a biologically very heterogeneous tumor with its clinical manifestation ranging from spontaneous regression to highly aggressive metastatic disease. Several adverse factors have been linked to oncogenesis, tumor progression and metastases of neuroblastoma including NMYC amplification, the neural adhesion molecule NCAM, as well as CXCR4 as a promoter of metastases. In this study, we investigate to what extent the expression of AQP1 in neuroblastoma correlates with changing cellular factors such as the hypoxic status, differentiation, expression of known adverse factors such as NMYC and NCAM, and CXCR4-related metastatic spread. Our results show that while AQP1 expression leads to an increased migratory behavior of neuroblastoma cells under hypoxic conditions, we find that hypoxia is associated with a reduction of NMYC in the same cells. A similar effect can be observed when using the tetracycline driven mechanism of SH-EP/Tet cells. When NMYC is not expressed, the expression of AQP1 is increased together with an increased expression of HIF-1α and HIF-2α. We furthermore show that when growing cells in different cell densities, they express AQP1, HIF-1α, HIF-2α, NMYC and NCAM to different degrees. AQP1 expression correlates with a hypoxic profile of these cells with increased HIF-1α and HIF-2α expression, as well as with NMYC and NCAM expression in two out of three neuroblastoma cell lines. When investigating cell properties of the cells that actually migrate, we find that the increased APQ1 expression in the migrated cells correlates with an increased NMYC and NCAM expression again in two out of three cell lines. Expression of the tumor cell homing marker CXCR4 varies between different tumor areas and between cell lines. While some migrated tumor cells highly express CXCR4, cells of other origin do not. In the initial phase of migration, we determined a dominant role of AQP1 expression of migrating cells in the scratch assay.

Neural Adhesion Molecule Close Homolog of L1 Deficiency Exacerbates DSS-Induced Colitis in Mice

Background: The cell adhesion molecule CHL1, which belongs to the immunoglobulin superfamily, functions in a variety of physiological and pathological processes including neural development, tissue injury and repair. Recently, we found CHL1 was co-localized with GFAP positive cells in mouse colon tissue. Methods: Here, Colon tissues were collected from CHL1+/+ , CHL1+/- and CHL1-/- mice after dextran sodium sulfate (DSS) induced to investigate the effects of CHL1 on the development of DSS-induced colitis. Results: The data showed that CHL1 expression was increased in distal colon in a time-dependent manner after DSS-treatment. CHL1 deficiency induced more pronounced colitis features, an exacerbation of inflammation and damage to colonic tissues in DSS-induced mouse than that of wild type mouse. Moreover, CHL1-/- mice showed a remarkable increase of neutrophil and macrophage infiltration into colonic tissues, and then result in more severe damage to the intestinal epithelial cells and FITC leakage in CHL1 deficiency mice than that in WT mouse. Conclusions: Our results revealed a distinct colonic role for CHL1 in regulating DSS-induced colitis, CHL1 deficiency exacerbates DSS-induced colitis in mice, indicating that CHL1 may be an attractive therapeutic target for IBD.

3D Images of Neuronal Adhesion Molecule Contactin-2 Reveal an Unanticipated Two-State Architecture

ABSTRACTContactins (CNTNs) are important cell adhesion molecules that mediate neuronal and axoglial contacts, and lesions in these molecules are linked to neuropsychiatric disorders. The extracellular domain of CNTNs contains six Ig domains and four FNIII domains. Crystal structures have shown that Ig1-Ig4 forms a horseshoe-shaped headpiece, in which the N-terminal domains might fold back on the C-terminal domains to form molecular super-U shaped architecture. The arrangement of these domains has been controversial, which may due to the structural dynamics and conformation heterogeneity of the protein. Here, we used a single-molecule 3D imaging method, individual-particle electron tomography (IPET), to study the extracellular domain of CNTN2 that forms monomers with a broad spectrum of conformations, and obtained 60 three-dimensional (3D) reconstructions. In addition to the known horseshoe-shaped headpiece, ~75% headpieces unexpectedly adopt an open (elongated) or a semi-open conformations contributed to our understanding about structural dynamics. The ectodomains formed curve but not double-back in any uniform way, with an averaged molecular dimension of ~255 Å. The first-time demonstration of the dynamic nature and conformational preferences of the full-length CNTN2 ectodomain suggest that the headpiece exists in equilibrium in the ‘closed’ or ‘not-closed’ states. The important architecture may provide a structural platform for protein partners to influence this balance regulating the function of CNTN2. Encoding the ability of this neural adhesion molecule to form both homomers with itself, as well as recruit different protein partner to neuronal and axoglial contact points play the key role in mediating cell-cell interactions.