RESUMEN
Expansion of the lysosomal apparatus occurs in subcortical white matter in brains from persons with AIDS. This study examined whether HIV-associated subcortical dementia (HAD) is significantly related to this lysosomal anomaly. Brain cortex and adjacent white matter from the middle frontal gyrus were obtained from the National NeuroAIDS Tissue Consortium. Lysosomal hydrolase activity was assayed in 57 subjects who underwent neuropsychological testing within 6 months prior to autopsy. Decedents were evaluated from 4 geographical sites in the United States: Galveston/Houston, Texas (n = 36), Los Angeles, California (n = 5), New York, New York (n = 5), and San Diego, California (n = 11). Increased beta-glucuronidase activity, a representative lysosomal glycosidase, was correlated with the amount of neurocognitive impairment. Significant correlation was present in 5 of 7 functional testing domains, including some that draw upon frontal lobe output (r = 0.419; P < 0.002). The biochemical anomaly was negligible in cerebral cortex and cerebrospinal fluid and was not correlated with brain dysfunction in those compartments. Glycosidase activation was associated significantly with increased HIV RNA concentration in brain tissue (r = 0.469; P < 0.021) and possibly with HIV RNA in cerebrospinal fluid (r = 0.266; P < 0.067). HIV RNA in blood plasma was not correlated. These results support the suggestion that abnormal metabolism in white matter glial cells contributes to cognitive slowing in persons with HAD. Because membrane turnover is routed through the endosome-lysosome apparatus, these data are in agreement with brain spectroscopic data that have suggested that there is an increase in membrane turnover in white matter glia.
Asunto(s)
Complejo SIDA Demencia/fisiopatología , Lóbulo Frontal/fisiopatología , Lisosomas/enzimología , Complejo SIDA Demencia/enzimología , Terapia Antirretroviral Altamente Activa , Trastornos del Conocimiento/fisiopatología , Lóbulo Frontal/enzimología , Lóbulo Frontal/ultraestructura , VIH-1 , Humanos , ARN Viral/líquido cefalorraquídeoRESUMEN
A gene expression profile of the human brain cortex was performed in people with HIV-1-associated dementia (HAD) using Affymetrix HG-U133 chips. Messenger RNA transcripts in middle frontal gyrus from subjects with HAD or milder neurocognitive dysfunction were compared to HIV-negative people. The analysis focused on ionic conductance carriers that control membrane excitation. Overexpressed ionic channel genes in brain cortex of subjects with dementia included (1) a calcium-driven K+ channel that prolongs afterhyperpolarization (AHP) current, (2) a leak type of K+ channel that prolongs the AHP, (3) an adenosine receptor that modulates cationic current via G proteins, (4) a G protein-coupled serotonin receptor that modulates cyclic AMP-linked current transduction, (5) a G protein-coupled dopamine receptor, (6) a GABA receptor subunit that conducts chloride current. Underexpressed current generators in the demented subjects included (1) two voltage-gated K+ channels that influence refractory periods and the onset of AHP, (2) a Na+ channel subunit that modifies current inactivation and the onset of the AHP, (3) a neuronal type of voltage-sensitive Ca+ channel that controls postsynaptic membrane excitability, (4) a metabotropic glutamate receptor that regulates cationic gating via G protein coupling, (5) A specific Galpha protein that transduces metabotropic cationic current, (6) an NMDA receptor subunit, (7) a glycine receptor subunit that modulates chloride current. These gene expression shifts probably occurred in neurons because they were not present in gyral white matter. Acquired neuronal channelopathies were not associated with a generalized shift of neuronal or glial cell markers, which suggest that they were not an artifact produced by neurodegeneration and/or glial cell proliferation. Channelopathies were not correlated with a generalized increase of inflammatory cell transcripts and were present in demented people without, and with HIV encephalitis (HIVE). We surveyed experimentally induced perturbations of these channels to determine the implications for brain function. Eleven experimental channelopathies produced decreased neuronal firing frequencies and pacemaker rates in model neurons; seven channelopathies increase neuronal firing rates experimentally. The implied disruption of neuronal excitability is consistent with some features of HAD, including its potential reversibility after HIV-1 replication is suppressed, the abnormal electroencephalographic recordings, the lack of clear-cut correlation with neurodegeneration and the lack of strict correlation with brain inflammation. The channelopathy concept may have wide relevance to the subcortical dementias.
Asunto(s)
Complejo SIDA Demencia/complicaciones , Trastornos del Conocimiento/etiología , Canales Iónicos/metabolismo , Receptores de Superficie Celular/metabolismo , Complejo SIDA Demencia/genética , Complejo SIDA Demencia/metabolismo , Adulto , Trastornos del Conocimiento/genética , Trastornos del Conocimiento/metabolismo , Femenino , Perfilación de la Expresión Génica/métodos , Humanos , Canales Iónicos/clasificación , Canales Iónicos/genética , Masculino , Persona de Mediana Edad , Examen Neurológico , Pruebas Neuropsicológicas , Cambios Post Mortem , ARN Mensajero/biosíntesis , ARN Mensajero/metabolismo , Receptores de Superficie Celular/clasificación , Receptores de Superficie Celular/genéticaRESUMEN
The thrombin peptide, TP508, accelerates tissue repair and initiates a cascade of cellular events. We have previously shown that alpha-thrombin induces cytokine expression in human mononuclear cells. We, therefore, investigated the possibility that TP508 might activate cytokine production and intracellular signaling pathways associated with cytokine activation. Our results show that TP508 induces cytokine expression in human mononuclear cells. TP508 treatment enhances extracellular signal-regulated kinase (Erk1/2) activities in U937 cells, as well as Erk1/2 and p38 activation in Jurkat T cells. These data support the hypothesis that TP508 may accelerate tissue repair through the activation of the inflammatory response.
Asunto(s)
Citocinas/metabolismo , Péptidos/farmacología , Transducción de Señal/efectos de los fármacos , Trombina/farmacología , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Relación Dosis-Respuesta a Droga , Activación Enzimática/efectos de los fármacos , Ensayo de Inmunoadsorción Enzimática , Humanos , Immunoblotting , Interleucina-1/metabolismo , Interleucina-2/metabolismo , Células Jurkat , Cinética , Leucocitos Mononucleares/efectos de los fármacos , Lipopolisacáridos/farmacología , Proteína Quinasa 1 Activada por Mitógenos/efectos de los fármacos , Proteína Quinasa 3 Activada por Mitógenos/efectos de los fármacos , Oligonucleótidos Antisentido/farmacología , Péptidos/química , Fosforilación , Fitohemaglutininas/farmacología , Trombina/química , Células U937 , Proteínas Quinasas p38 Activadas por Mitógenos/efectos de los fármacosRESUMEN
The matrin 3 family of nuclear proteins consists of members with potentially diverse activities. Matrin 3 and NP220 share RNA-binding domains, and NP220 has been shown to recognize and bind to the DNA sequence, CCCCC (G/C). We have isolated and characterized another member of the matrin 3 family, designated NP94, from a medulloblastoma. This protein, also named Ciz1, has previously been characterized for its ability to interact with p21(Cip1/Waf1) and contains 3 zinc finger domains and a matrin 3-homologous domain 3. Our immunofluorescence and Northern blot analysis data indicate that Ciz1 is localized in the nucleus and is expressed in a wide range of tissues, especially the pancreas and the brain; within the brain, the highest message levels are found in the cerebellum. A modified selected and amplified binding (SAAB) sequence method was used to identify DNA sequences recognized by Ciz1. From the analysis of the retrieved SAAB sequences and verification using electrophoretic mobility shift assays, we formulated a consensus DNA sequence, ARYSR(0-2)YYAC, recognized by Ciz1. The potential activities of Ciz1, including those involved in brain tumorigenesis, are discussed.