RESUMO
Neuregulin (NRG) stimulation of ErbB4 signaling is important for type II cell surfactant synthesis. ErbB4 may mediate gene expression via a non-canonical pathway involving enzymatic cleavage releasing its intracellular domain (4ICD) for nuclear trafficking and gene regulation. The accepted model for release of 4ICD is consecutive cleavage by Tumor necrosis factor alpha Converting Enzyme (TACE) and γ-secretase enzymes. Here, we show that 4ICD mediates surfactant synthesis and its release by γ-secretase is not dependent on previous TACE cleavage. We used siRNA to silence Presenilin-1 (PSEN-1) expression in a mouse lung type II epithelial cell line (MLE12 cells), and both siRNA knockdown and chemical inhibition of TACE. Knockdown of PSEN-1 significantly decreased baseline and NRG-stimulated surfactant phospholipid synthesis, expression of the surfactant proteins SP-B and SP-C, as well as 4ICD levels, with no change in ErbB4 ectodomain shedding. Neither siRNA knockdown nor chemical inhibition of TACE inhibited 4ICD release or surfactant synthesis. PSEN-1 cleavage of ErbB4 for non-canonical signaling through 4ICD release does not require prior cleavage by TACE.
Assuntos
Proteínas ADAM/genética , Diferenciação Celular/genética , Receptores ErbB/metabolismo , Presenilina-1/genética , Proteínas ADAM/antagonistas & inibidores , Proteína ADAM17 , Células Epiteliais Alveolares/metabolismo , Secretases da Proteína Precursora do Amiloide/metabolismo , Animais , Linhagem Celular , Receptores ErbB/genética , Regulação da Expressão Gênica , Camundongos , Neuregulina-1/genética , Presenilina-1/antagonistas & inibidores , Alvéolos Pulmonares/citologia , Alvéolos Pulmonares/metabolismo , Surfactantes Pulmonares/metabolismo , RNA Interferente Pequeno , Receptor ErbB-4RESUMO
The complex nature and difficult-to-establish aetiology of chronic pruritus (CP) makes it challenging to provide medical care for patients with CP. This challenge can only be met with a multidisciplinary approach. The first multidisciplinary Itch Centre in Germany was established at the University of Münster in 2002 to meet the needs of this patient population. More than 2,500 outpatients and 400 inpatients are diagnosed and receive treatment each year. To ensure evidence-based medical care, an electronic system for medical documentation and patient-reported outcomes was established. Automated data transfer to a research database enables comprehensive data analysis. Our translational research has characterized peripheral and central itch mechanisms, provided novel clustering of CP patients, and identified novel target-specific therapies (e.g. neurokinin 1 receptor-antagonist). The multidisciplinary approach, combined with basic, clinical and translational research, enables comprehensive medical care of patients as well as implementation of high-quality experimental and clinical studies.