Assuntos
Antígenos CD4/história , Linfócitos T CD4-Positivos/enzimologia , Linfócitos T CD4-Positivos/imunologia , Receptores Proteína Tirosina Quinases/história , Sequência de Aminoácidos , Animais , Antígenos CD4/metabolismo , Linfócitos T CD4-Positivos/virologia , Linhagem Celular Transformada , Detergentes , HIV/imunologia , HIV/patogenicidade , História do Século XX , Humanos , Ativação Linfocitária/imunologia , Camundongos , Dados de Sequência Molecular , Receptores Proteína Tirosina Quinases/metabolismo , Transdução de Sinais/imunologia , Frações Subcelulares/enzimologia , Frações Subcelulares/imunologia , Especificidade por Substrato/imunologia , Células U937RESUMO
The immune system works through leukocytes interacting with each other, with other cells, with tissue matrices, with infectious agents, and with other antigens. These interactions are mediated by cell-surface glycoproteins and glycolipids. Antibodies against these leukocyte molecules have provided powerful tools for analysis of their structure, function, and distribution. Antibodies have been used widely in hematology, immunology, and pathology, and in research, diagnosis, and therapy. The associated CD nomenclature is commonly used when referring to leukocyte surface molecules and antibodies against them. It provides an essential classification for diagnostic and therapeutic purposes. The most recent (8th) Workshop and Conference on Human Leukocyte Differentiation Antigens (HLDA), held in Adelaide, Australia, in December 2004, allocated 95 new CD designations and made radical changes to its aims and future operational strategy in order to maintain its relevance to modern human biology and clinical practice.
Assuntos
Antígenos CD/classificação , Terminologia como Assunto , Antígenos CD/imunologia , Diferenciação Celular , Humanos , Reprodutibilidade dos TestesRESUMO
We previously cloned Siva-1 by using the cytoplasmic tail of CD27, a member of the tumor necrosis factor receptor family, as the bait in the yeast two-hybrid system. The Siva gene is organized into four exons that code for the predominant full-length Siva-1 transcript, whereas its alternate splice form, Siva-2, lacks exon 2 coding sequence. Various groups have demonstrated a role for Siva-1 in several apoptotic pathways. Interestingly, the proapoptotic properties of Siva-1 are lacking in Siva-2. The fact that Siva-1 is partly localized to mitochondria despite the absence of any mitochondrial targeting signal, it harbors a 20-aa-long putative amphipathic helical structure that is absent in Siva-2, and that its expression is restricted to double-positive (CD3(+), CD4(+), CD8(+)) thymocytes like BCL-X(L), prompted us to test for a potential interaction between Siva-1 and BCL-X(L). Here, we show that Siva-1 binds to and inhibits BCL-X(L)-mediated protection against UV radiation-induced apoptosis. Indeed, the unique amphipathic helical region (SAH) present in Siva-1 is required for its binding to BCL-X(L) and sensitizing cells to UV radiation. Natural complexes of Siva-1/BCL-X(L) are detected in HUT78 and murine thymocyte, suggesting a potential role for Siva-1 in regulating T cell homeostasis.
