RESUMEN
Beta-amyloid (Abeta) deposition and senile plaque-associated astrocytes are common neuropathological features of Alzheimer's disease (AD). Although the molecular mechanisms by which Abeta contributes to the progression of neuropathologic changes have not been entirely established, there is little doubt that the association of Abeta with astrocytes, the predominant cell type in brain, significantly influences exacerbation of the disease. In an effort to identify astrocyte-derived molecules that may be intimately associated with progression of AD, we identified a novel Abeta-induced rat gene, designated Mib, whose human counterpart covers KIAA0233. Mib-transfected C6 cells express Mib protein in the endoplasmic reticulum and endplasmic reticulum-Golgi-intermediate compartment. To evaluate roles of Mib in AD, we investigated its expression in the AD brain. In non-AD brains, Mib mRNA has been detected in neurons but not in quiescent astrocytes. On the contrary, in AD brains, Mib mRNA is expressed in activated astrocytes associated with senile plaques, but not expressed in neurons around lesions. From these observations, Mib appears to be a novel Abeta-responsive gene that may play a role in astrocyte inflammatory activation around senile plaques in the AD brain.
Asunto(s)
Enfermedad de Alzheimer/metabolismo , Astrocitos/metabolismo , Encefalitis/metabolismo , Gliosis/metabolismo , Proteínas de la Membrana/metabolismo , Placa Amiloide/metabolismo , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/fisiopatología , Animales , Secuencia de Bases , Línea Celular Tumoral , Células Cultivadas , Encefalitis/genética , Encefalitis/fisiopatología , Retículo Endoplásmico/metabolismo , Retículo Endoplásmico/ultraestructura , Regulación de la Expresión Génica/genética , Gliosis/genética , Gliosis/fisiopatología , Aparato de Golgi/metabolismo , Aparato de Golgi/ultraestructura , Humanos , Canales Iónicos , Proteínas de la Membrana/genética , Proteínas de la Membrana/aislamiento & purificación , Datos de Secuencia Molecular , Placa Amiloide/genética , ARN Mensajero/metabolismo , Ratas , Homología de Secuencia de Aminoácido , Activación Transcripcional/genética , Regulación hacia Arriba/genéticaRESUMEN
Lib, first identified as a novel beta-amyloid responsive gene in rat astrocytes, has an extracellular domain of 15 leucine-rich repeats (LRRs) followed by a transmembrane domain and a short cytoplasmic region. It is a distinctly inducible gene and is thought to play a key role in inflammatory states via the LRR extracellular motif, an ideal structural framework for protein-protein and protein-matrix interactions. To evaluate potential roles of Lib, we screened various tumors for Lib expression. Lib mRNA expression was high and uniquely expressed in breast tumor tissues, compared to paired normal breast tissues. Lib mRNA was localized in the ductal carcinoma cells and Lib protein displayed a homophilic association on the surface of cultured cells. These data suggest that Lib may play a role in the progression of breast carcinomas and may be a diagnostic marker for breast tumors.
Asunto(s)
Neoplasias de la Mama/genética , Carcinoma/genética , Proteínas de la Membrana/genética , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/patología , Carcinoma/metabolismo , Carcinoma/patología , Femenino , Humanos , Proteínas de la Membrana/biosíntesis , ARN Mensajero/metabolismoRESUMEN
The information conveyed from dendritic cells (DCs) to naïve CD4(+) T cells has crucial influence on their differentiation toward effector T cells. In an effort to identify DC-derived molecules directly contributing to T cell differentiation, we searched for molecules distinctively expressed between two DC subtypes, which were differentiated from peripheral monocytes by cultivation with GM-CSF (for DC1) or IL-3 (for DC2) in the presence of IL-4 and had the ability to induce naïve T cells to differentiate into Th1 or Th2 cells, respectively. As the first step to address this issue, we subtracted DC1 transcripts from those of DC2 and compiled the gene profile dominantly expressed in DC2, whose products are known to reside in other than the nucleus. Intriguingly, many of them were molecules involved in Th2-skewed disease pathologies, such as FN1, ITGAE, GPNMB, PLAUR, FPRL2, LILRB4, SERPINE1, ALOX15, TBXAS1, NCF2, CCL3, IL1RN, SPARC, and STAB1, suggesting that DCs function not only as antigen presenting cells but also as producers of Th2 pathology specific milieus leading to disease deteriorations. We also found that expressions of CYP27A1, PPAP2B, RSAD2, and ABCC3 were up-regulated in DC2, implying their significant function in Th2-deviated states. The identification of differentially expressed genes between DC subtypes provides new insights into their functions and our comparative gene expression profile will be highly useful for the identification of DC-derived key molecules for T cell differentiation.
Asunto(s)
Células Dendríticas/metabolismo , Monocitos/metabolismo , Linfocitos T/metabolismo , Células Th2/metabolismo , Antígenos CD/genética , Antígenos CD/metabolismo , Antígeno B7-2/metabolismo , Diferenciación Celular/efectos de los fármacos , Células Cultivadas , Colestanotriol 26-Monooxigenasa/genética , Técnicas de Cocultivo , Células Dendríticas/citología , Células Dendríticas/efectos de los fármacos , Fibronectinas/genética , Perfilación de la Expresión Génica , Factor Estimulante de Colonias de Granulocitos y Macrófagos/farmacología , Humanos , Inmunoglobulinas/metabolismo , Cadenas alfa de Integrinas/genética , Interferón gamma/metabolismo , Interleucina-3/farmacología , Interleucina-4/metabolismo , Interleucina-5/metabolismo , Prueba de Cultivo Mixto de Linfocitos , Glicoproteínas de Membrana/metabolismo , Monocitos/citología , Monocitos/efectos de los fármacos , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Linfocitos T/citología , Linfocitos T/efectos de los fármacos , Células TH1/citología , Células TH1/efectos de los fármacos , Células TH1/metabolismo , Células Th2/citología , Células Th2/efectos de los fármacos , Antígeno CD83RESUMEN
In an effort to identify astrocyte-derived molecules that may be intimately associated with progression of Alzheimer's disease (AD), Lib, a type I transmembrane protein belonging to leucine-rich repeat superfamily, has been identified as a distinctly inducible gene, responsive to beta-amyloid as well as pro-inflammatory cytokines in astrocytes. To evaluate the roles of Lib in AD, we investigated Lib expression in AD brain. In non-AD brain, Lib mRNA has been detected in neurons but not in quiescent astrocytes. On the contrary, in AD brain, Lib mRNA is expressed in activated astrocytes associated with senile plaques, but not expressed in neurons around lesions. Lib-expressing glioma cells displayed promotion of migration ability through reconstituted extracellular matrix and recombinant Lib protein bound to constituents of extracellular matrix. These observations suggest that Lib may contribute to regulation of cell-matrix adhesion interactions with respect to astrocyte recruitment around senile plaques in AD brain.
Asunto(s)
Astrocitos/metabolismo , Matriz Extracelular/metabolismo , Proteínas de la Membrana/química , Proteínas de la Membrana/fisiología , Neuroglía/citología , Placa Amiloide/metabolismo , Transcripción Genética , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/metabolismo , Astrocitos/citología , Western Blotting , Encéfalo/metabolismo , Estudios de Casos y Controles , Adhesión Celular , Línea Celular Tumoral , Movimiento Celular , Femenino , Humanos , Hibridación in Situ , Leucina/química , Masculino , Persona de Mediana Edad , Neuronas/metabolismo , ARN Mensajero/metabolismo , Proteínas Recombinantes/química , TransfecciónRESUMEN
beta-Amyloid (Abeta) deposition and senile plaque-associated astrocytes are common neuropathological features of Alzheimer's disease (AD). Although the molecular mechanisms by which Abeta contributes to the progression of neuropathologic changes have not been established entirely, there is little doubt that the association of Abeta with astrocytes, the predominant cell type in brain, has significant influence on exacerbation of the disease. In an effort to identify key molecules involved in AD, we investigated Abeta-responsive genes using rat astrocytes. In this study, we identified a novel Abeta-induced rat gene, designated as Lib, encoding a type I transmembrane protein with an extracellular domain that contains fifteen leucine-rich repeats (LRRs). Human counterpart of rat Lib is located on chromosome 3q29 and human Lib mRNA found in particularly placenta. Lib mRNA levels in rat C6 astrocytoma cells can be increased by pro-inflammatory cytokines and the rat Lib-transfected cells express Lib protein on the cell surfaces. Lib appears to be a member of the LRR superfamily which is involved in cell-cell and/or -extracellular matrix interactions including adhesion or target recognition in neuroinflammatory states.