RESUMO
Mutations of CD95 and CD95L, lpr and gld, respectively, are associated with spontaneous autoimmune disease and alteration of immune privilege. In lpr or gld animals these processes would be expected to exacerbate experimental allergic encephalomyelitis (EAE), an animal model of the autoimmune demyelinating disease multiple sclerosis. However, here we show that the lpr and gld mutations did not overcome the MHC-defined limits of disease and, surprisingly, did not exacerbate the pathology of EAE on a sensitive haplotype. In fact, the mutations dramatically ameliorated clinical signs of EAE without affecting the development of a Th1 response or inflammatory cell infiltration into the central nervous system. Fewer apoptotic cells were detected in inflammatory lesions of lpr mice than in wild-type lesions of similar severity. Our results indicate that CD95L is not an instrumental component of immune privilege in the central nervous system, and that functional CD95 and CD95L are important for the progression of clinical disease.
Assuntos
Apoptose/imunologia , Encefalomielite Autoimune Experimental/etiologia , Encefalomielite Autoimune Experimental/imunologia , Glicoproteínas de Membrana/fisiologia , Medula Espinal/imunologia , Receptor fas/fisiologia , Animais , Apoptose/genética , Movimento Celular/genética , Movimento Celular/imunologia , Encefalomielite Autoimune Experimental/genética , Proteína Ligante Fas , Cobaias , Ligantes , Ativação Linfocitária/genética , Transtornos Linfoproliferativos/genética , Transtornos Linfoproliferativos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos MRL lpr , Camundongos Mutantes , Proteína Básica da Mielina/imunologia , Medula Espinal/patologia , Células Th1/imunologiaRESUMO
We have taken a combined genetic and biochemical approach to study TATA-binding protein (TBP) structure-function relationships. Using site-directed mutagenesis coupled with a screen for conditional lethal growth, we have isolated a number of temperature-sensitive TBP alleles in the region of amino acid positions 188, 189, and 190. Conditional growth is not a result of increased TBP turnover as most of the mutant proteins are stable in vivo as evidenced by immunoblot detection of TBP steady-state levels. DNA binding assays reveal that mutations at position 188 do not affect DNA binding activity of these mutants, even at high temperatures. Utilizing whole cell extracts which contain mutant TBPs in in vitro transcription experiments, we confirm that TBP is required for transcription by all three nuclear polymerases. However, certain of our TBP mutants are only compromised for RNA polymerase II transcription.
