RESUMO
Here we characterize leukocyte mono-Ig-like receptor 7 (LMIR7)/CLM-3 and compare it with an activating receptor, LMIR4/CLM-5, that is a counterpart of an inhibitory receptor LMIR3/CLM-1. LMIR7 shares high homology with LMIR4 in the amino acid sequences of its Ig-like and transmembrane domains. Flow cytometric analysis demonstrated that LMIR4 was predominantly expressed in neutrophils, whereas LMIR7 was highly expressed in mast cells and monocytes/macrophages. Importantly, LMIR7 engagement induced cytokine production in bone marrow-derived mast cells (BMMCs). Although FcRγ deficiency did not affect surface expression levels of LMIR7, it abolished LMIR7-mediated activation of BMMCs. Consistently we found significant interaction of LMIR7-FcRγ, albeit with lower affinity compared with that of LMIR4-FcRγ. Our results showed that LMIR7 transmits an activating signal through interaction with FcRγ. In addition, like LMIR4, LMIR7 synergizes with TLR4 in signaling. Analysis of several chimera receptors composed of LMIR4 and LMIR7 revealed these findings: 1) the transmembrane of LMIR7 with no charged residues maintained its surface expression at high levels in the absence of FcRγ; 2) the extracellular juxtamembrane region of LMIR7 had a negative effect on its surface expression levels; and 3) the strong interaction of LMIR4 with FcRγ depended on the extracellular juxtamembrane region as well as the transmembrane domain of LMIR4. Thus, LMIR7 shares similarities with LMIR4, although they are differentially regulated in their distribution, expression, and function.
Assuntos
Perfilação da Expressão Gênica , Receptores Imunológicos/genética , Sequência de Aminoácidos , Animais , Western Blotting , Células da Medula Óssea/metabolismo , Linhagem Celular , Células Cultivadas , Quimiocinas/metabolismo , Citocinas/metabolismo , Citometria de Fluxo , Células HEK293 , Humanos , Macrófagos/citologia , Macrófagos/metabolismo , Mastócitos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Dados de Sequência Molecular , Monócitos/citologia , Monócitos/metabolismo , Ligação Proteica , Receptores de IgG/genética , Receptores de IgG/metabolismo , Receptores Imunológicos/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Homologia de Sequência de AminoácidosRESUMO
The current medical examinations for detecting endometrial cancer can sometimes be stressful and inconvenient for examinees and examiners. Therefore, we attempted to develop an autoscan-virtual cytology system for detecting endometrial cancer without relying on judgment by the human eye. Exfoliated cells from the uterus were retrieved using a tampon inserted for 3 h. More than 100 monoclonal antibodies (mAb) developed by us were screened in three steps of immunohistochemistry to find mAb sets that would enable the cancer and normal endometrium to be perfectly distinguished. The exfoliated cells provided by 30 endometrial cancer patients and a total of 37 samples of 14 non-malignant volunteers including the menstrual cycle were analyzed using imaging cytometry. All samples contained epithelial cells and dysplasia cells, but the pathologist could not definitively diagnose all of them as endometrial cancer cells because most cells had degenerated. Twenty-two of 28 endometrial cancer tissues (79%) were positive with four mAb sets, CRELD1, GRK5, SLC25A27 and STC2, and 22 of 22 normal endometriums (100%) were negative. Our newly developed autoscan-virtual cytology for exfoliated endometrial cells showed overall sensitivity for endometrial cancer patients and overall specificity for volunteers of 50% (15/30) and 95% (35/37), respectively. Our autoscan-virtual cytology combined with cancer-specific mAb and imaging cytometry could be useful for endometrial cancer detection. Autoscan-virtual cytology for endometrial cancer deserves further evaluation for future endometrial cancer screening.