RESUMEN
After traumatic spinal cord injury (SCI), there is an opportunity for preserving function by attenuating secondary cell loss. Astrocytes play crucial roles in the adult CNS and are responsible for the vast majority of glutamate buffering, potentially preventing excitotoxic loss of neurons and oligodendrocytes. We examined spatial and temporal changes in gene expression of the major astrocyte glutamate transporter GLT1 following moderate thoracic contusion SCI using transgenic BAC-GLT1-eGFP promoter reporter mice. In dorsal column white matter, total intensity of GLT1-eGFP expression per region was significantly reduced following SCI at both lesion epicenter and at rostral and caudal areas where no tissue loss occurred. This regional decrease in GLT1 expression was due to significant loss of GLT1-eGFP(+) cells, partially accounted for by apoptosis of eGFP(+) /GFAP(+) astrocytes in both white and gray matter. There were also decreased numbers of GLT1-eGFP-expressing cells in multiple gray matter regions following injury; nevertheless, there was sustained or even increased regional GLT1-eGFP expression in gray matter as a result of up-regulation in astrocytes that continued to express GLT1-eGFP. Although there were increased numbers of GFAP(+) cells both at the lesion site and in surrounding intact spinal cord following SCI, the majority of proliferating Ki67(+) /GFAP(+) astrocytes did not express GLT1-eGFP. These findings demonstrate that spatial and temporal alterations in GLT1 expression observed after SCI result from both astrocyte death and gene expression changes in surviving astrocytes. Results also suggest that following SCI a significant portion of astrocytes lacks GLT1 expression, possibly compromising the important role of astrocytes in glutamate homeostasis.
Asunto(s)
Astrocitos/metabolismo , Transportador 2 de Aminoácidos Excitadores/genética , Ácido Glutámico/fisiología , Regiones Promotoras Genéticas/genética , Traumatismos de la Médula Espinal/genética , Médula Espinal/metabolismo , Animales , Astrocitos/patología , Proliferación Celular , Supervivencia Celular/genética , Modelos Animales de Enfermedad , Transportador 2 de Aminoácidos Excitadores/metabolismo , Regulación de la Expresión Génica/fisiología , Proteínas Fluorescentes Verdes/genética , Ratones , Ratones Transgénicos , Médula Espinal/patología , Traumatismos de la Médula Espinal/metabolismo , Traumatismos de la Médula Espinal/patología , Factores de TiempoRESUMEN
Here, we report two complete genome sequences of human adenovirus 55 (HAdV-55) isolates, from a patient in Pennsylvania in 2006 and a U.S. military member in South Korea in 2019. The findings demonstrate the continued global transmission of HAdV-55 viruses in both military and civilian populations.