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Cell Membrane Protein (cell + membrane_protein)
Selected AbstractsExpression of the caveolins in dermal vascular tumorsJOURNAL OF CUTANEOUS PATHOLOGY, Issue 1 2001Michael B. Morgan Introduction: Histopathologic criteria are usually sufficient for the accurate distinction of benign from malignant dermal vascular tumors. A minority of cases, however, pose a vexing diagnostic dilemma. Recent studies suggest that caveolin, a scaffolding cell membrane protein, may prove helpful in predicting the biologic behavior of endothelial-derived neoplasms. Methods: We analyzed a series of 30 dermal vascular tumors including 12 lobular capillary hemangiomas (LCH), 4 cases of targetoid hemosiderotic hemangiomas (TH), 4 cases of tufted angioma (TA), 12 cases of Kaposi's sarcoma (KS), 4 epithelioid (EH) and 1 spindle cell hemangioendothelioma (SH), and 4 cases of angiosarcoma (AS). The distribution of immunoreactivity was analyzed by quantifying cell membrane staining in each case. Results: There was a statistically significant difference in the expression of caveolin between LCH (mean labeling index=91.6), TH (mean labeling index=89.7), and TA (mean labeling index=87.2) and the cases of KS (mean labeling index=21.6, EH mean labeling index=23.1), and the AS ( mean labeling index=6.3). Conclusions: These results indicate that antibodies to caveolin may be useful in separating benign and malignant dermal vascular tumors and possibly implicates this peptide in their pathogenesis. [source] Disposition of axonal caspr with respect to glial cell membranes: Implications for the process of myelinationJOURNAL OF NEUROSCIENCE RESEARCH, Issue 15 2009Liliana Pedraza Abstract Neurofascin-155 (NF155) and caspr are transmembrane proteins found at discrete locations early during development of the nervous system. NF155 is present in the oligodendrocyte cell body and processes, whereas caspr is on the axonal surface. In mature nerves, these proteins are clustered at paranodes, flanking the node of Ranvier. To understand how NF155 and caspr become localized to the paranodal regions of myelinated nerves, we have studied their distribution over time in myelinating cultures. Our observations indicate that these two proteins are recruited to the cell surface at the contact zone between axons and oligodendrocytes, where they trans-interact. This association explains the early pattern of caspr distribution, a helical coil that winds around the axon, resembling the turns of the myelin sheath. Caspr, an axonal membrane protein, therefore seems to move in register with the overlying myelinating cell via its interactions with myelin proteins. We suggest that NF155 is the glial cell membrane protein responsible for caspr distribution. The pair act as interacting partners on either side of the axoglial contact area. Most likely, there are other proteins on the axonal surface whose distribution is equally influenced by interaction with the nascent myelin sheath. The fact that caspr follows the movement of the spiraling membrane has a direct affect on the interpretation of the way in which myelin is formed. © 2009 Wiley-Liss, Inc. [source] Differential sensitivity in the survival of oligodendrocyte cell lines to overexpression of myelin proteolipid protein gene productsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 6 2001Ernesto R. Bongarzone Abstract The proteolipid (PLP) gene encodes at least four proteins, including the classic PLP and DM20, which are important components of the myelin sheath, and the recently identified soma-restricted (sr) isoforms, srPLP and srDM20. The classic PLP and DM20 gene products have been implicated in oligodendrocyte survival by overexpression studies in vitro and in vivo. The classic and sr proteolipids are targeted to different cellular compartments in the oligodendrocyte, suggesting different cellular functions. Accordingly, we examined the effects of in vitro overexpression of the sr-PLP/DM20 isoforms on the survival of stably transfected, conditionally immortalized, oligodendroglial cell lines and compared this to overexpression of the classic and the jimpy-mutated proteolipids. The results indicate that overexpression of either normal or jimpy classic PLP/DM20 resulted in a dramatic reduction in the survival of the oligodendrocyte cell lines at the nonpermissive temperature, but not the COS-7 cell line, a cell line expressing the same oncogene constitutively. Survival of the oligodendrocyte cell lines was significantly less affected when either the sr-PLP/DM20 or the dopamine D-2 receptor, another cell membrane protein, was overexpressed in the cell lines. These results suggest that overexpression of the "classic" PLP or DM20 can compromise the survival of oligodendrocytes whether or not they are mutated. Furthermore, they suggest that the internal mechanisms for normal targeting of the PLP/DM20 isoforms of either the "classic" or the "sr" types influence the oligodendrocyte's ability to survive when these proteolipids are overexpressed. J. Neurosci. Res. 65:485,492, 2001. © 2001 Wiley-Liss, Inc. [source] Effects of ELF magnetic field on membrane protein structure of living HeLa cells studied by Fourier transform infrared spectroscopyBIOELECTROMAGNETICS, Issue 7 2003Toshitaka Ikehara Abstract The effects of exposure to a 50 Hz magnetic field (maximum of 41.7 to 43.6 mT) on the membrane protein structures of living HeLa cells were studied using attenuated total reflection infrared spectroscopy. One min of such exposure shifted peak absorbance of the amide I band to a smaller wave number, reduced peak absorbance of the amide II band, and increased absorbance at around 1600 cm,1. These results suggest that exposure to the ELF magnetic field has reversible effects on the N,H inplane bending and C,N stretching vibrations of peptide linkages, and changes the secondary structures of ,-helix and ,-sheet in cell membrane proteins. Bioelectromagnetics 24:457,464, 2003. © 2003 Wiley-Liss, Inc. [source] Involvement of a novel ADP-ribosylation factor GTPase-activating protein, SMAP, in membrane trafficking: Implications in cancer cell biologyCANCER SCIENCE, Issue 9 2006Kenji Tanabe The endocytosis of cell membrane proteins is initiated by the binding of activated Arf6, a member of Ras-related GTPases, to the PM. A GAP specific for Arf6 triggers the budding of endocytotic vesicles from the PM by inactivating GTP-bound Arf6. We recently identified the SMAP gene that encodes an ArfGAP and is involved in the endocytosis of TfnR and possibly E-cadherin. In this review, we summarize the process of intracellular membrane trafficking, highlighting the roles played by the SMAP gene. Progression of cancer to malignancy occurs in parallel with the disappearance of E-cadherin, a central component of the adherens junction in epithelial cells. Therefore, elucidation of the molecular mechanism of E-cadherin endocytosis should be one of the key elements in tumor cell biology. (Cancer Sci 2006; 97: 801,806) [source] | |||||||||||||