RESUMO
In many cell types, nuclear A-type lamins regulate multiple cellular functions, including higher-order genome organization, DNA replication and repair, gene transcription, and signal transduction; however, their role in specialized immune cells remains largely unexplored. We showed that the abundance of A-type lamins was almost negligible in resting naïve T lymphocytes, but was increased upon activation of the T cell receptor (TCR). The increase in lamin-A was an early event that accelerated formation of the immunological synapse between T cells and antigen-presenting cells. Polymerization of F-actin in T cells is a critical step for immunological synapse formation, and lamin-A interacted with the linker of nucleoskeleton and cytoskeleton (LINC) complex to promote F-actin polymerization. We also showed that lamin-A expression accelerated TCR clustering and led to enhanced downstream signaling, including extracellular signal-regulated kinase 1/2 (ERK1/2) signaling, as well as increased target gene expression. Pharmacological inhibition of the ERK pathway reduced lamin-A-dependent T cell activation. Moreover, mice lacking lamin-A in immune cells exhibited impaired T cell responses in vivo. These findings underscore the importance of A-type lamins for TCR activation and identify lamin-A as a previously unappreciated regulator of the immune response.
Assuntos
Citoesqueleto de Actina/imunologia , Actinas/imunologia , Sinapses Imunológicas/imunologia , Lamina Tipo A/imunologia , Ativação Linfocitária/fisiologia , Linfócitos T/imunologia , Citoesqueleto de Actina/genética , Actinas/genética , Animais , Humanos , Sinapses Imunológicas/genética , Células Jurkat , Lamina Tipo A/genética , Sistema de Sinalização das MAP Quinases/genética , Sistema de Sinalização das MAP Quinases/imunologia , Camundongos , Camundongos Knockout , Proteína Quinase 1 Ativada por Mitógeno/genética , Proteína Quinase 1 Ativada por Mitógeno/imunologia , Proteína Quinase 3 Ativada por Mitógeno/genética , Proteína Quinase 3 Ativada por Mitógeno/imunologia , Receptores de Antígenos de Linfócitos T/genética , Receptores de Antígenos de Linfócitos T/imunologia , Linfócitos T/citologiaRESUMO
Gene mutations that cause defects in the nuclear envelope are responsible for progeroid syndromes, characterized by exacerbated cell senescence and accelerated aging. Consequently, morphological abnormalities of the nucleus represent a cellular phenotype whose analysis allows for both the characterization of the consequences of particular mutations and the assessment of the impact of approaches aimed at reversing their pathological effects. To obtain reliable results, systematic and reproducible procedures are required. Here, we describe a simple fluorescence microscopy-based protocol to detect nuclear envelope alterations in the study of cellular senescence.
