RESUMO
Leukocytes are constantly produced in the bone marrow and released into the circulation. Many different leukocyte subpopulations exist that exert distinct functions. Leukocytes are recruited to sites of inflammation and combat the cause of inflammation via many different effector functions. Virtually all of these processes depend on dynamic actin remodeling allowing leukocytes to adhere, migrate, phagocytose, and release granules. However, actin dynamics are not possible without actin-binding proteins (ABP) that orchestrate the balance between actin polymerization, branching, and depolymerization. The homologue of the ubiquitous ABP cortactin in hematopoietic cells is hematopoietic cell-specific lyn substrate-1, often called hematopoietic cell-specific protein-1 (HCLS1 or HS1). HS1 has been reported in different leukocytes to regulate Arp2/3-dependent migration. However, more evidence is emerging that HS1 functions go far beyond just being a direct actin modulator. For example, HS1 is important for the activation of GTPases and integrins, and mediates signaling downstream of many receptors including BCR, TCR, and CXCR4. In this review, we summarize current knowledge on HS1 functions and discuss them in a pathophysiologic context.
Assuntos
Complexo 2-3 de Proteínas Relacionadas à Actina/genética , Actinas/genética , Leucemia/genética , Leucócitos/imunologia , Quinases da Família src/genética , Complexo 2-3 de Proteínas Relacionadas à Actina/imunologia , Actinas/imunologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/imunologia , Animais , Células da Medula Óssea/imunologia , Células da Medula Óssea/patologia , Adesão Celular , Linhagem da Célula/genética , Linhagem da Célula/imunologia , Movimento Celular , Proliferação de Células , Cortactina/genética , Cortactina/imunologia , Regulação da Expressão Gênica , Humanos , Leucemia/imunologia , Leucemia/patologia , Leucócitos/classificação , Leucócitos/patologia , Fagocitose , Ligação Proteica , Transdução de Sinais , Quinases da Família src/imunologiaRESUMO
The intestinal epithelium constitutes a first line of defense of the innate immune system. Epithelial dysfunction is a hallmark of intestinal disorders such as inflammatory bowel diseases (IBDs). The actin cytoskeleton controls epithelial barrier integrity but the function of actin regulators such as cortactin is poorly understood. Given that cortactin controls endothelial permeability, we hypothesized that cortactin is also important for epithelial barrier regulation. We found increased permeability in the colon of cortactin-KO mice that was accompanied by reduced levels of ZO-1, claudin-1, and E-cadherin. By contrast, claudin-2 was upregulated. Cortactin deficiency increased RhoA/ROCK1-dependent actomyosin contractility, and inhibition of ROCK1 rescued the barrier defect. Interestingly, cortactin deficiency caused increased epithelial proliferation without affecting apoptosis. KO mice did not develop spontaneous colitis, but were more susceptible to dextran sulfate sodium colitis and showed severe colon tissue damage and edema formation. KO mice with colitis displayed strong mucus deposition and goblet cell depletion. In healthy human colon tissues, cortactin co-localized with ZO-1 at epithelial cell contacts. In IBDs patients, we observed decreased cortactin levels and loss of co-localization with ZO-1. Thus, cortactin is a master regulator of intestinal epithelial barrier integrity in vivo and could serve as a suitable target for pharmacological intervention in IBDs.
Assuntos
Actomiosina/metabolismo , Colite/imunologia , Cortactina/metabolismo , Doenças Inflamatórias Intestinais/imunologia , Mucosa Intestinal/patologia , Quinases Associadas a rho/metabolismo , Proteína rhoA de Ligação ao GTP/metabolismo , Animais , Apoptose , Proliferação de Células , Colite/induzido quimicamente , Cortactina/genética , Citoesqueleto/metabolismo , Sulfato de Dextrana , Modelos Animais de Doenças , Humanos , Imunidade Inata , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína da Zônula de Oclusão-1/metabolismo , Proteína rhoA de Ligação ao GTP/genéticaRESUMO
Changes in vascular permeability occur during inflammation and the actin cytoskeleton plays a crucial role in regulating endothelial cell contacts and permeability. We demonstrated recently that the actin-binding protein cortactin regulates vascular permeability via Rap1. However, it is unknown if the actin cytoskeleton contributes to increased vascular permeability without cortactin. As we consistently observed more actin fibres in cortactin-depleted endothelial cells, we hypothesised that cortactin depletion results in increased stress fibre contractility and endothelial barrier destabilisation. Analysing the contractile machinery, we found increased ROCK1 protein levels in cortactin-depleted endothelium. Concomitantly, myosin light chain phosphorylation was increased while cofilin, mDia and ERM were unaffected. Secretion of the barrier-stabilising hormone adrenomedullin, which activates Rap1 and counteracts actomyosin contractility, was reduced in plasma from cortactin-deficient mice and in supernatants of cortactin-depleted endothelium. Importantly, adrenomedullin administration and ROCK1 inhibition reduced actomyosin contractility and rescued the effect on permeability provoked by cortactin deficiency in vitro and in vivo. Our data suggest a new role for cortactin in controlling actomyosin contractility with consequences for endothelial barrier integrity.
Assuntos
Adrenomedulina/metabolismo , Permeabilidade Capilar/fisiologia , Cortactina/deficiência , Células Endoteliais/fisiologia , Actomiosina/fisiologia , Animais , Proteínas Contráteis/biossíntese , Proteínas Contráteis/genética , Cortactina/antagonistas & inibidores , Cortactina/genética , Cortactina/fisiologia , Células Endoteliais da Veia Umbilical Humana , Humanos , Pulmão/citologia , Masculino , Camundongos , Interferência de RNA , RNA Interferente Pequeno/genética , Complexo Shelterina , Proteínas de Ligação a Telômeros/metabolismo , Proteínas rap1 de Ligação ao GTP/metabolismo , Quinases Associadas a rho/antagonistas & inibidores , Quinases Associadas a rho/fisiologiaRESUMO
The endothelium is the first barrier that leukocytes have to overcome during recruitment to sites of inflamed tissues. The leukocyte extravasation cascade is a complex multistep process that requires the activation of various adhesion molecules and signaling pathways, as well as actin remodeling, in both leukocytes and endothelial cells. Endothelial adhesion molecules, such as E-selectin or ICAM-1, are connected to the actin cytoskeleton via actin-binding proteins (ABPs). Although the contribution of receptor-ligand interactions to leukocyte extravasation has been studied extensively, the contribution of endothelial ABPs to the regulation of leukocyte adhesion and transendothelial migration remains poorly understood. This review focuses on recently published evidence that endothelial ABPs, such as cortactin, myosin, or α-actinin, regulate leukocyte extravasation by controlling actin dynamics, biomechanical properties of endothelia, and signaling pathways, such as GTPase activation, during inflammation. Thus, ABPs may serve as targets for novel treatment strategies for disorders characterized by excessive leukocyte recruitment.
Assuntos
Actinas/imunologia , Cortactina/imunologia , Endotélio Vascular/imunologia , Leucócitos/imunologia , Miosinas/imunologia , Migração Transendotelial e Transepitelial/imunologia , Actinas/genética , Animais , Adesão Celular/genética , Adesão Celular/imunologia , Cortactina/genética , Endotélio Vascular/patologia , Humanos , Inflamação/genética , Inflamação/imunologia , Molécula 1 de Adesão Intercelular/genética , Molécula 1 de Adesão Intercelular/imunologia , Leucócitos/patologia , Miosinas/genética , Pirofosfatases/genética , Pirofosfatases/imunologia , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Migração Transendotelial e Transepitelial/genéticaRESUMO
The cortactin gene, mapped at 11q13, has been associated with an aggressive clinical course in many cancers because of its function of invasiveness. This study evaluated CTTN protein and its prognostic value in the deep invasive front and superficial areas of laryngeal squamous cell carcinomas. The transcript expression levels were evaluated in a subset of cases. Overexpression of CTTN cytoplasmatic protein (80% of cases in both the deep invasive front and superficial areas) and transcript (30% of samples) was detected in a significant number of cases. In more than 20% of cases, observation verified membrane immunostaining in the deep invasive front and superficial areas. Perineural invasion was significantly associated with N stage and recurrence (P = .0058 and P = .0037, respectively). Higher protein expression levels were correlated with perineural invasion (P = .004) in deep invasive front cells, suggesting that this area should be considered a prognostic tool in laryngeal carcinomas. Although most cases had moderate to strong CTTN expression on the tumor surface, 2 sets of cases revealed a differential expression pattern in the deep invasive front. A group of cases with absent to weak expression of CTTN in the deep invasive front showed good prognosis parameters, and a second group with moderate to strong expression of CTTN were associated with an unfavorable prognosis, suggesting an association with worse outcome. Taken together, these results suggest that the deep invasive front might be considered a grading system in laryngeal carcinomas and that cortactin is a putative marker of worse outcome in the deep invasive front of laryngeal carcinomas.