RESUMO
There is increasing evidence that inducing neuronal mitophagy can be used as a therapeutic intervention for Alzheimer's disease. Here, we screen a library of 2024 FDA-approved drugs or drug candidates, revealing UMI-77 as an unexpected mitophagy activator. UMI-77 is an established BH3-mimetic for MCL-1 and was developed to induce apoptosis in cancer cells. We found that at sub-lethal doses, UMI-77 potently induces mitophagy, independent of apoptosis. Our mechanistic studies discovered that MCL-1 is a mitophagy receptor and directly binds to LC3A. Finally, we found that UMI-77 can induce mitophagy in vivo and that it effectively reverses molecular and behavioral phenotypes in the APP/PS1 mouse model of Alzheimer's disease. Our findings shed light on the mechanisms of mitophagy, reveal that MCL-1 is a mitophagy receptor that can be targeted to induce mitophagy, and identify MCL-1 as a drug target for therapeutic intervention in Alzheimer's disease.
Assuntos
Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Mitofagia/efeitos dos fármacos , Mitofagia/fisiologia , Proteína de Sequência 1 de Leucemia de Células Mieloides/efeitos dos fármacos , Proteína de Sequência 1 de Leucemia de Células Mieloides/metabolismo , Animais , Apoptose/efeitos dos fármacos , Proteína 5 Relacionada à Autofagia/economia , Sobrevivência Celular , Modelos Animais de Doenças , Técnicas de Inativação de Genes , Glucose , Células HEK293 , Células HeLa , Ensaios de Triagem em Larga Escala , Humanos , Peptídeos e Proteínas de Sinalização Intracelular , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas Associadas aos Microtúbulos/metabolismo , Proteína de Sequência 1 de Leucemia de Células Mieloides/genética , Proteínas de Neoplasias , Proteínas do Tecido Nervoso , Neurônios/metabolismo , Oxigênio , Receptores Citoplasmáticos e Nucleares , Sulfonamidas/farmacologia , Tioglicolatos/farmacologiaRESUMO
The islet in type 2 diabetes (T2D) is characterized by amyloid deposits derived from islet amyloid polypeptide (IAPP), a protein co-expressed with insulin by ß-cells. In common with amyloidogenic proteins implicated in neurodegeneration, human IAPP (hIAPP) forms membrane permeant toxic oligomers implicated in misfolded protein stress. Here, we establish that hIAPP misfolded protein stress activates HIF1α/PFKFB3 signaling, this increases glycolysis disengaged from oxidative phosphorylation with mitochondrial fragmentation and perinuclear clustering, considered a protective posture against increased cytosolic Ca2+ characteristic of toxic oligomer stress. In contrast to tissues with the capacity to regenerate, ß-cells in adult humans are minimally replicative, and therefore fail to execute the second pro-regenerative phase of the HIF1α/PFKFB3 injury pathway. Instead, ß-cells in T2D remain trapped in the pro-survival first phase of the HIF1α injury repair response with metabolism and the mitochondrial network adapted to slow the rate of cell attrition at the expense of ß-cell function.
Assuntos
Diabetes Mellitus Tipo 2/patologia , Estresse do Retículo Endoplasmático/fisiologia , Células Secretoras de Insulina/patologia , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Resposta a Proteínas não Dobradas/fisiologia , Adulto , Animais , Animais Geneticamente Modificados , Apoptose , Linhagem Celular Tumoral , Diabetes Mellitus Tipo 2/metabolismo , Modelos Animais de Doenças , Glicólise/fisiologia , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Polipeptídeo Amiloide das Ilhotas Pancreáticas/genética , Masculino , Pessoa de Meia-Idade , Mitofagia/fisiologia , Fosforilação Oxidativa , Fosfofrutoquinase-2/metabolismo , Agregados Proteicos/fisiologia , RatosRESUMO
Mitophagy has been implicated in mitochondrial quality control and in various human diseases. However, the study of in vivo mitophagy remains limited. We previously explored in vivo mitophagy using a transgenic mouse expressing the mitochondria-targeted fluorescent protein Keima (mt-Keima). Here, we generated mt-Keima Drosophila to extend our efforts to study mitophagy in vivo. A series of experiments confirmed that mitophagy can be faithfully and quantitatively measured in mt-Keima Drosophila. We also showed that alterations in mitophagy upon environmental and genetic perturbation can be measured in mt-Keima Drosophila. Analysis of different tissues revealed a variation in basal mitophagy levels in Drosophila tissues. In addition, we found a significant increase in mitophagy levels during Drosophila embryogenesis. Importantly, loss-of-function genetic analysis demonstrated that the phosphatase and tensin homolog-induced putative kinase 1 (PINK1)-Parkin pathway is essential for the induction of mitophagy in vivo in response to hypoxic exposure and rotenone treatment. These studies showed that the mt-Keima Drosophila system is a useful tool for understanding the role and molecular mechanism of mitophagy in vivo. In addition, we demonstrated the essential role of the PINK1-Parkin pathway in mitophagy induction in response to mitochondrial dysfunction.-Kim, Y. Y., Um, J.-H., Yoon, J.-H., Kim, H., Lee, D.-Y., Lee, Y. J., Jee, H. J., Kim, Y. M., Jang, J. S., Jang, Y.-G., Chung, J., Park, H. T., Finkel, T., Koh, H., Yun, J. Assessment of mitophagy in mt-Keima Drosophila revealed an essential role of the PINK1-Parkin pathway in mitophagy induction in vivo.