RESUMEN
In bilaterally symmetric animals, many axons cross the midline to interconnect the left and right sides of the central nervous system (CNS). This process is critical for the establishment of neural circuits that control the proper integration of information perceived by the organism and the resulting response. While neurons at different levels of the CNS project axons across the midline, the molecules that regulate this process are common to many if not all midline-crossing regions. This article reviews the molecules that function as guidance cues at the midline in the developing vertebrate spinal cord, cortico-spinal tract and corpus callosum. As well, we describe the mutations that have been identified in humans that are linked to axon guidance and midline-crossing defects.
Asunto(s)
Axones/fisiología , Cuerpo Calloso/metabolismo , Regulación del Desarrollo de la Expresión Génica , Malformaciones del Sistema Nervioso/genética , Neurogénesis/genética , Médula Espinal/metabolismo , Vertebrados/metabolismo , Animales , Cuerpo Calloso/citología , Receptor DCC , Genética Médica , Humanos , Ratones , Ratones Noqueados , Mutación , Factores de Crecimiento Nervioso/genética , Factores de Crecimiento Nervioso/metabolismo , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/metabolismo , Malformaciones del Sistema Nervioso/metabolismo , Malformaciones del Sistema Nervioso/patología , Netrina-1 , Receptores de Superficie Celular/genética , Receptores de Superficie Celular/metabolismo , Receptores Inmunológicos/genética , Receptores Inmunológicos/metabolismo , Médula Espinal/citología , Proteínas Supresoras de Tumor/genética , Proteínas Supresoras de Tumor/metabolismo , Vertebrados/genética , Proteínas RoundaboutRESUMEN
The Smad family of proteins are critical components of the TGFbeta superfamily signalling pathway. Ligand addition induces phosphorylation of specific receptor-regulated Smads, which then form heteromeric complexes with the common mediator Smad, Smad4. This complex then translocates from the cytoplasm into the nucleus. Once there, the R-Smad/Smad4 complex interacts with a variety of DNA binding proteins and is thereby targetted to a diverse array of gene promoters. The Smad-containing DNA binding complex can then positively or negatively regulate gene expression through the recruitment of co-activators and co-repressors. Xenopus FAST (now known as FoxH1) was the first Smad DNA binding partner identified and the FoxH1 family now includes related proteins from mouse, human and Zebrafish. In all organisms examined, FoxH1 is expressed primarily during the earliest stages of development and thus FoxH1 is thought to play a critical role in mediating TGFbeta superfamily signals during these early developmental stages. Other Smad partners range from those that are ubiquitously expressed to others that are present only in specific cell types or developmental stages. Thus, it is the interaction of Smads with a wide range of specific transcriptional partners that is important for the generation of diverse biological responses to TGFbeta superfamily members.
Asunto(s)
Activinas/farmacología , Proteínas de Unión al ADN/farmacología , Transactivadores/farmacología , Factores de Transcripción/farmacología , Transcripción Genética/efectos de los fármacos , Factor de Crecimiento Transformador beta/farmacología , Proteínas de Xenopus , Proteínas de Pez Cebra , Activinas/fisiología , Animales , Proteínas de Unión al ADN/metabolismo , Proteínas de Unión al ADN/fisiología , Factores de Transcripción Forkhead , Humanos , Factores de Crecimiento Nervioso , Fosfoproteínas , Unión Proteica , Transducción de Señal/efectos de los fármacos , Proteínas Smad , Proteína Smad1 , Proteína Smad2 , Proteína smad3 , Proteína Smad4 , Proteína Smad5 , Proteína smad6 , Proteína smad7 , Proteína Smad8 , Transactivadores/metabolismo , Transactivadores/fisiología , Factores de Transcripción/metabolismo , Factores de Transcripción/fisiología , Transcripción Genética/fisiologíaRESUMEN
OBJECTIVE: Endomysial autoantibodies (EmA) are specific for celiac disease. The target antigen has been identified as tissue tranglutaminase (tTG). Our aim was to study the accuracy of a newly developed enzyme-linked immunosorbent assay (ELISA) for easy detection of tTG autoantibodies. METHODS: Thirty-one sera from patients with histologically proven celiac disease and 23 healthy controls were examined for EmA using monkey esophagus and human umbilical cord as substrate. IgA-tTG autoantibodies were determined by newly developed ELISA. Additionally, sera from patients with dermatitis herpetiformis (n = 20), inflammatory bowel disease (IBD; n = 32), chronic liver disease (n = 36), and diabetes mellitus (n = 19) were tested. RESULTS: The sensitivity of the tTG autoantibody ELISA accounted for 90% detection in patients with untreated celiac disease. The specificity was 76% owing to positive values in the lower range in patients with IBD (15%), chronic liver disease (36%), and diabetes (22%), all of whom were negative for EmA. In dermatitis herpetiformis patients 90% were EmA-positive. Of these, only 47% showed elevated tTG autoantibodies. Preincubation of sera from dermatitis patients with tTG abolished immunofluorescent staining of endomysial structures. CONCLUSION: Detection of mid- to high-titer tTG autoantibodies is highly specific for celiac disease. However, in the low-titer range, overlap exists with liver disease, IBD, and diabetes. Tissue transglutaminase autoantibodies may evolve as a new screening and follow-up method for celiac disease. Although tTG seems to be a major autoantigen in dermatitis herpetiformis, the low sensitivity of both tTG ELISA and immunofluorescence using human umbilical cord suggests differential involvement of tTG in this disease.
Asunto(s)
Autoanticuerpos/análisis , Enfermedad Celíaca/inmunología , Dermatitis Herpetiforme/inmunología , Transglutaminasas/inmunología , Animales , Ensayo de Inmunoadsorción Enzimática , Esófago/inmunología , Técnica del Anticuerpo Fluorescente , Haplorrinos/inmunología , Humanos , Técnicas In Vitro , Sensibilidad y Especificidad , Cordón Umbilical/inmunologíaRESUMEN
CEACAM1, also known as C-CAM, BGP and CD66a, is a member of the carcinoembryonic antigen (CEA) family which is itself part of the immunoglobulin supergene family. CEACAM1 is involved in intercellular adhesion, signal transduction and tumor cell growth regulation. CEACAM1 is down-regulated in colon and prostate carcinomas, as well as in endometrial, bladder and hepatic tumors, and 30% of breast cancers. We have shown in a mouse colon tumor model that CEACAM1 with a long cytoplasmic domain inhibited the development of tumors whereas a splice variant lacking the cytoplasmic domain did not. In this study, we define the subregions of the long cytoplasmic domain participating in the tumor inhibition phenotype of CEACAM1. We show that a single point mutation of Tyr488, conforming to an Immunoreceptor Tyrosine Inhibition Motif (ITIM), was sufficient to reverse the in vivo tumor cell growth inhibition. Substitution or deletion of residues in the C-terminal region of the CEACAM1 cytoplasmic domain also led to reversal of tumor cell growth inhibition. This result is in agreement with our previous studies demonstrating the C-terminal region of the cytoplasmic domain influences the levels of CEACAM1 Tyr phosphorylation and its association with the protein Tyr phosphatases SHP-1 and SHP-2. Furthermore, removal of the N-terminal domain of CEACAM1, essential for intercellular adhesion, did not impair the tumor inhibitory effect. These results suggest that Tyr phosphorylation or dephosphorylation of the CEACAM1 cytoplasmic domain represents a crucial step in the control of epithelial cell proliferation.
Asunto(s)
Adenosina Trifosfatasas/fisiología , Moléculas de Adhesión Celular/fisiología , Neoplasias Colorrectales/enzimología , Proteínas de Neoplasias/fisiología , Isoformas de Proteínas/fisiología , Células 3T3 , Adenosina Trifosfatasas/biosíntesis , Adenosina Trifosfatasas/química , Adenosina Trifosfatasas/genética , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Animales , Antígenos CD , Antígeno Carcinoembrionario/genética , Carcinoma/genética , Carcinoma/metabolismo , Carcinoma/patología , Adhesión Celular , Moléculas de Adhesión Celular/biosíntesis , Moléculas de Adhesión Celular/química , Moléculas de Adhesión Celular/genética , Cromosomas Humanos Par 19/genética , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/metabolismo , Neoplasias Colorrectales/patología , Regulación Neoplásica de la Expresión Génica , Glicoproteínas , Humanos , Péptidos y Proteínas de Señalización Intracelular , Masculino , Ratones , Ratones Endogámicos BALB C , Datos de Secuencia Molecular , Familia de Multigenes , Mutagénesis Sitio-Dirigida , Proteínas de Neoplasias/biosíntesis , Proteínas de Neoplasias/genética , Fosforilación , Mutación Puntual , Neoplasias de la Próstata/genética , Neoplasias de la Próstata/metabolismo , Neoplasias de la Próstata/patología , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Procesamiento Proteico-Postraduccional , Proteína Tirosina Fosfatasa no Receptora Tipo 11 , Proteína Tirosina Fosfatasa no Receptora Tipo 6 , Proteínas Tirosina Fosfatasas/metabolismo , Eliminación de Secuencia , Transducción de Señal , Relación Estructura-Actividad , Células Tumorales CultivadasRESUMEN
Biliary glycoproteins are members of the carcinoembryonic antigen (CEA) family and behave as cell adhesion molecules. The mouse genome contains two very similar Bgp genes, Bgp1 and Bgp2, whereas the human and rat genomes contain only one BGP gene. A Bgp2 isoform was previously identified as an alternative receptor for the mouse coronavirus mouse hepatitis virus. This isoform consists of two extracellular immunoglobulin domains, a transmembrane domain and a cytoplasmic tail of five amino acids. In this report, we have examined whether the Bgp2 gene can express other isoforms in different mouse tissues. We found only one other isoform, which has a long cytoplasmic tail of 73 amino acids. The long cytodomain of the Bgp2 protein is highly similar to that of the Bgp1/4L isoform. The Bgp2 protein is expressed in low amounts in kidney and in a rectal carcinoma cell line. Antibodies specific to Bgp2 detected a 42-kDa protein, which is expressed at the cell surface of these samples. Bgp2 was found by immunocytochemistry in smooth muscle layers of the kidney, the uterus, in gut mononuclear cells and in the crypt epithelia of intestinal tissues. Transfection studies showed that, in contrast with Bgp1, the Bgp2 glycoprotein was not directly involved in intercellular adhesion. However, this protein is found in the proliferative compartment of the intestinal crypts and in cells involved in immune recognition. This suggests that the Bgp2 protein represents a distinctive member of the CEA family; its unusual expression patterns in mouse tissues and the unique functions it may be fulfilling may provide novel clues about the multiple functions mediated by a common BGP protein in humans and rats.
Asunto(s)
Adhesión Celular/efectos de los fármacos , Glicoproteínas/genética , Secuencia de Aminoácidos , Animales , Antígenos CD , Moléculas de Adhesión Celular/genética , Línea Celular , Clonación Molecular , Regulación de la Expresión Génica , Glicoproteínas/metabolismo , Inmunohistoquímica , Ratones , Ratones Endogámicos BALB C , Datos de Secuencia Molecular , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Alineación de SecuenciaRESUMEN
Biliary glycoprotein (Bgp, C-CAM, or CD66a) is an immunoglobulin-like cell adhesion molecule and functions as a tumor suppressor protein. We have previously shown that the Bgp1 isoform responsible for inhibition of colonic, liver, prostate, and breast tumor cell growth contains within its cytoplasmic domain two tyrosine residues positioned in immunoreceptor tyrosine-based inhibition motif (ITIM) consensus sequences. Moreover, we determined that these residues, upon phosphorylation, associate with the protein-tyrosine phosphatase SHP-1. In this report, we have further evaluated the structural bases of the association of Bgp1 with Tyr phosphatases. First, we demonstrate that Bgp1 also associates with the SHP-2 Tyr phosphatase, but not with an unrelated Tyr phosphatase, PTP-PEST. Association of Bgp1 and SHP-2 involves the Tyr residues within the Bgp1 ITIM sequences, Val at position +3 relative to the second Tyr (Tyr-515), and the SHP-2 N-terminal SH2 domain. In addition, our results indicate that residues +4, +5, and +6 relative to Tyr-515 in the Bgp1 cytoplasmic domain play a significant role in these interactions, as their deletion reduced Bgp1 Tyr phosphorylation and association with SHP-1 and SHP-2 by as much as 80%. Together, these results indicate that both SHP-1 and SHP-2 interact with the Bgp1 cytoplasmic domain via ITIM-like sequences. Furthermore, they reveal that the C-terminal amino acids of Bgp1 are critical for these interactions.
Asunto(s)
Glicoproteínas/metabolismo , Proteínas Tirosina Fosfatasas/metabolismo , Tirosina/metabolismo , Secuencia de Aminoácidos , Animales , Antígenos CD , Secuencia de Bases , Moléculas de Adhesión Celular , Línea Celular , Citoplasma/metabolismo , Citosol/metabolismo , Cartilla de ADN , Células Epiteliales/enzimología , Glicoproteínas/química , Humanos , Péptidos y Proteínas de Señalización Intracelular , Ratones , Datos de Secuencia Molecular , Fosforilación , Proteína Tirosina Fosfatasa no Receptora Tipo 11 , Proteína Tirosina Fosfatasa no Receptora Tipo 6 , Proteínas Tirosina Fosfatasas con Dominio SH2 , Células Tumorales CultivadasRESUMEN
We have prospectively searched for IgA anti-transglutaminase antibodies by an enzyme-linked immunosorbent assay test in 20 untreated coeliacs and 21 patients with small bowel diseases other than coeliac disease consecutively referred to our Malabsorption Clinic. All the untreated coeliacs and one out of 21 disease controls turned out to be positive for the presence of these antibodies. The use of the enzyme-linked immunosorbent assay test for anti-transglutaminase antibodies could represent a new screening test for coeliac disease, in fact, this new enzyme-linked immunosorbent assay test has an absolute sensitivity and a satisfactory specificity and, in comparison to antiendomysial antibodies, is less expensive and avoids the ethical problems related to the use of monkey oesophagus.
Asunto(s)
Enfermedad Celíaca/diagnóstico , Inmunoglobulina A/análisis , Tamizaje Masivo/métodos , Transglutaminasas/inmunología , Adulto , Especificidad de Anticuerpos , Ensayo de Inmunoadsorción Enzimática , Femenino , Técnica del Anticuerpo Fluorescente Indirecta , Humanos , Masculino , Estudios Prospectivos , Sensibilidad y EspecificidadRESUMEN
The evidence suggests that the propagation of neoplastic cells by solid tumors, seem the platelets have a protective role on the neoplastic cells respect to immunocompetent system. In this study, the AA. valued the variation of platelet aggregation induced by collagen when PRP was incubated with liquid culture of neoplastic cells K562. The preliminary results, show the platelet aggregation induced by collagen, increase alter interaction with this liquid culture.
Asunto(s)
Colágeno/farmacología , Medios de Cultivo/farmacología , Agregación Plaquetaria/efectos de los fármacos , Adulto , Humanos , Leucemia Eritroblástica Aguda/patología , Masculino , Metástasis de la Neoplasia , Células Tumorales CultivadasRESUMEN
In this study, the authors wanted to investigate the volume, density, and percentage of three platelet subpopulations present in adult and geriatric males. Ninety subjects, between the ages of 20 and 40, were chosen for the adult group and 50 subjects, all older than age 70, were used for the geriatric group. The platelet subpopulations were separated with discontinuous gradients of Percoll. The results obtained from the three platelet subpopulations--low, intermediate, and high density--show different volumes and percentages in both the groups studied. From the information that larger platelets can be expected to have a longer life span, it was possible to hypothesize that platelets found in geriatric males have a reduced average life span. It is also clear that platelets exist that have similar volumes but different densities.
Asunto(s)
Plaquetas/clasificación , Adulto , Anciano , Envejecimiento/sangre , Humanos , Persona de Mediana Edad , Recuento de PlaquetasRESUMEN
The study of platelet aggregation is normally carried out with the use of "Platelet Rich Plasma" (PRP) in which is grouped the overall platelets population. We have divided this population in three defined subclasses by gradients with discontinuous density, so as to test their own functional response towards three aggregant agents: adenosine diphosphate, epinephrine and collagen. The obtained results have been compared by an Aggregation Index, calculated as a ratio between the maximum percentage of aggregation and platelets mass. In this way it is pointed out a discriminating behaviour in three groups of thrombocytes relative to a functional different attitude towards different inducers and associated to an activation of heterogeneous way.