ABSTRACT
Mondini dysplasia is rare, but has an important association with recurrent bacterial meningitis. We herein describe the case of a 3-year-old girl with unilateral sensorineural hearing loss who presented with three independent episodes of bacterial meningitis within 8 months. Temporal bone computed tomography indicated the characteristic features of Mondini dysplasia in the right inner ear. This was treated by surgical closure of the inner ear defect via oval window and additional vaccination was administered. Appropriate vaccination might prevent the recurrent bacterial meningitis associated with Mondini dysplasia.
Subject(s)
Bacteria/isolation & purification , Hearing Loss, Sensorineural/complications , Histiocytosis, Langerhans-Cell/complications , Immunocompromised Host , Meningitis, Bacterial/complications , Child, Preschool , Female , Hearing Loss, Sensorineural/diagnosis , Histiocytosis, Langerhans-Cell/diagnosis , Humans , Meningitis, Bacterial/diagnosis , Meningitis, Bacterial/microbiology , Tomography, X-Ray ComputedABSTRACT
Mutation in Cu/Zn-superoxide dismutase (SOD1) is a cause of familial amyotrophic lateral sclerosis (ALS). Mutant SOD1 protein (SOD1(mut)) induces motor neuron death, although the molecular mechanism of SOD1(mut)-induced cell death remains controversial. Here we show that SOD1(mut) specifically interacted with Derlin-1, a component of endoplasmic reticulum (ER)-associated degradation (ERAD) machinery and triggered ER stress through dysfunction of ERAD. SOD1(mut)-induced ER stress activated the apoptosis signal-regulating kinase 1 (ASK1)-dependent cell death pathway. Perturbation of binding between SOD1(mut) and Derlin-1 by Derlin-1-derived oligopeptide suppressed SOD1(mut)-induced ER stress, ASK1 activation, and motor neuron death. Moreover, deletion of ASK1 mitigated the motor neuron loss and extended the life span of SOD1(mut) transgenic mice. These findings demonstrate that ER stress-induced ASK1 activation, which is triggered by the specific interaction of Derlin-1 with SOD1(mut), is crucial for disease progression of familial ALS.
Subject(s)
Amyotrophic Lateral Sclerosis/genetics , Amyotrophic Lateral Sclerosis/pathology , Endoplasmic Reticulum/pathology , MAP Kinase Kinase Kinase 5/metabolism , Motor Neurons/pathology , Superoxide Dismutase/genetics , Animals , Cell Death , Cell Line , Enzyme Activation , Gene Expression Regulation , Humans , Membrane Proteins/metabolism , Mice , Mice, Transgenic , Mutation , Signal TransductionABSTRACT
Extracellular ATP, an autocrine or paracrine intercellular transmitter, is known to induce apoptosis in macrophages. However, the precise signaling mechanisms of ATP-induced apoptosis remain to be elucidated. Here we showed that activation of p38 mitogen-activated protein kinase (MAPK) plays a critical role in ATP-induced apoptosis. p38 activation and apoptosis in macrophages were induced by ATP. ATP-induced apoptosis was mediated in part by production of reactive oxygen species (ROS) derived from NOX2/gp91(phox), a component of the NADPH oxidase complex expressed in macrophages and neutrophils. Furthermore, ATP-induced ROS generation, p38 activation, and apoptosis were almost completely inhibited by selective P2X(7) receptor antagonists. We also found that ATP-induced apoptosis were diminished in ASK1-deficient macrophages accompanied by the lack of p38 activation. These results demonstrate that ROS-mediated activation of the ASK1-p38 MAPK pathway downstream of P2X(7) receptor is required for ATP-induced apoptosis in macrophages.
