RESUMEN
The neuronal apoptosis inhibitory protein (NAIP) is a constituent of the inflammasome and a key component of the innate immune system. Here we use immunofluorescence to position NAIP within the cytokinetic apparatus, contiguous to chromosomal passenger complex (CPC), Centralspindlin, PRC1 and KIF4A. During metaphase, NAIP accumulates in the mitotic spindle poles and is shown in spindle microtubules; in anaphase NAIP is detected in the middle of the central spindle. At the end of cytokinesis, NAIP is localized in the outlying region of the stem body, the center of the intercellular bridge formed between daughter cells prior to cellular abscission. We also describe the sustained presence of NAIP mRNA and protein throughout the cell cycle with a significant increase observed in the G2/M phase. Consistent with a role for NAIP in cytokinesis, NAIP overexpression in HeLa cells promotes the acquisition of a multinuclear phenotype. Conversely, NAIP siRNA gene silencing results in an apoptotic lethal phenotype. Our confocal and super resolution stimulated-emission-depletion (STED) examination of mammalian cell cytokinesis demonstrate a potential new role for NAIP in addition to anti-apoptotic and innate immunology functions.
Asunto(s)
Citocinesis , Proteína Inhibidora de la Apoptosis Neuronal/genética , Proteína Inhibidora de la Apoptosis Neuronal/metabolismo , Huso Acromático/metabolismo , Proteínas de Ciclo Celular/metabolismo , Supervivencia Celular , Células HeLa , Humanos , Cinesinas/metabolismo , Microscopía Confocal , Mitosis , Fenotipo , Polos del Huso/metabolismo , Regulación hacia ArribaRESUMEN
BACKGROUND: Spinal Muscular Atrophy (SMA) is one of the most common inherited causes of infant death and is caused by the loss of functional survival motor neuron (SMN) protein due to mutations or deletion in the SMN1 gene. One of the treatment strategies for SMA is to induce the expression of the protein from the homologous SMN2 gene, a rescuing paralog for SMA. METHODS AND RESULTS: Here we demonstrate the promise of pharmacological modulation of SMN2 gene by BAY 55-9837, an agonist of the vasoactive intestinal peptide receptor 2 (VPAC2), a member of G protein coupled receptor family. Treatment with BAY 55-9837 lead to induction of SMN protein levels via activation of MAPK14 or p38 pathway in vitro. Importantly, BAY 55-9837 also ameliorated disease phenotype in severe SMA mouse models. CONCLUSION: Our findings suggest the VPAC2 pathway is a potential SMA therapeutic target.
Asunto(s)
Atrofia Muscular Espinal/tratamiento farmacológico , Fragmentos de Péptidos/uso terapéutico , Receptores de Tipo II del Péptido Intestinal Vasoactivo/agonistas , Proteína 1 para la Supervivencia de la Neurona Motora/metabolismo , Animales , Modelos Animales de Enfermedad , Ratones , Péptido Intestinal Vasoactivo/uso terapéuticoRESUMEN
BACKGROUND: Autosomal recessive spinal muscle atrophy (SMA) is characterized by the loss of α motor neurons resulting in progressive muscle loss and respiratory failure. SMA is one of the most common inherited causes of infant death with a carrier frequency of 1 in 50 and a calculated prevalence of about 1 in 11,000 live births in the US. The low amount of functional survival motor neuron (SMN) protein due to mutations or deletion in the SMN1 gene causes SMA. OBJECTIVE: A potential treatment strategy for SMA is to upregulate levels of SMN protein originating from the paralog SMN2 gene compensating in part for the absence of the SMN1 gene. Our group has previously shown that activation of the STAT5 pathway by lactation hormone prolactin (PRL) increased SMN levels, improved motor function and enhanced survival in a severe SMA mouse model. Given that human growth hormone (HGH) is also known to activate the STAT5 signalling pathway and is already used extensively in clinical settings, we thus elected to assess its impact on SMN levels. METHODS AND RESULTS: Administration of HGH in NT2 cells activated STAT5 pathway which resulted into significant induction in SMN protein levels. Furthermore, systemic administration of HGH to transgenic SMA mice induced SMN protein levels in the brain and spinal cord samples. Critically, HGH treatment improved disease phenotype and increased survival in two severe SMA mouse models. CONCLUSIONS: Our results confirm earlier work suggesting STAT5 pathway activators as potential therapeutic compounds for the treatment of SMA and identify HGH as one such promising agent.
RESUMEN
The loss of functional Survival Motor Neuron (SMN) protein due to mutations or deletion in the SMN1 gene causes autosomal recessive neurodegenerative spinal muscle atrophy (SMA). A potential treatment strategy for SMA is to upregulate the amount of SMN protein originating from the highly homologous SMN2 gene, compensating in part for the absence of the functional SMN1 gene. We have previously shown that in vitro activation of the p38 pathway stabilizes and increases SMN mRNA levels leading to increased SMN protein levels. In this report, we explore the impact of the p38 activating, FDA-approved, blood brain barrier permeating compound celecoxib on SMN levels in vitro and in a mouse model of SMA. We demonstrate a significant induction of SMN protein levels in human and mouse neuronal cells upon treatment with celecoxib. We show that activation of the p38 pathway by low doses celecoxib increases SMN protein in a HuR protein-dependent manner. Furthermore, celecoxib treatment induces SMN expression in brain and spinal cord samples of wild-type mice in vivo. Critically, celecoxib treatment increased SMN levels, improved motor function and enhanced survival in a severe SMA mouse model. Our results identify low dose celecoxib as a potential new member of the SMA therapeutic armamentarium.