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1.
Cell Death Dis ; 9(8): 797, 2018 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-30038238

RESUMO

DDHD2/KIAA0725p is a mammalian intracellular phospholipase A1 that exhibits phospholipase and lipase activities. Mutation of the DDHD2 gene causes hereditary spastic paraplegia (SPG54), an inherited neurological disorder characterized by lower limb spasticity and weakness. Although previous studies demonstrated lipid droplet accumulation in the brains of SPG54 patients and DDHD2 knockout mice, the cause of SPG54 remains elusive. Here, we show that ablation of DDHD2 in mice induces age-dependent apoptosis of motor neurons in the spinal cord. In vitro, motor neurons and embryonic fibroblasts from DDHD2 knockout mice fail to survive and are susceptible to apoptotic stimuli. Chemical and probe-based analysis revealed a substantial decrease in cardiolipin content and an increase in reactive oxygen species generation in DDHD2 knockout cells. Reactive oxygen species production in DDHD2 knockout cells was reversed by the expression of wild-type DDHD2, but not by an active-site DDHD2 mutant, DDHD2 mutants related to hereditary spastic paraplegia, or DDHD1, another member of the intracellular phospholipase A1 family whose mutation also causes spastic paraplegia (SPG28). Our results demonstrate the protective role of DDHD2 for mitochondrial integrity and provide a clue to the pathogenic mechanism of SPG54.


Assuntos
Apoptose , Fosfolipases A1/genética , Espécies Reativas de Oxigênio/metabolismo , Paraplegia Espástica Hereditária/patologia , Trifosfato de Adenosina/metabolismo , Animais , Apoptose/efeitos dos fármacos , Cardiolipinas/metabolismo , Células Cultivadas , Modelos Animais de Doenças , Fibroblastos/citologia , Fibroblastos/metabolismo , Humanos , Camundongos , Camundongos Knockout , Mitocôndrias/metabolismo , Neurônios Motores/citologia , Neurônios Motores/metabolismo , Fosfolipases , Fosfolipases A1/deficiência , Paraplegia Espástica Hereditária/genética , Medula Espinal/metabolismo , Medula Espinal/patologia , Estaurosporina/farmacologia
2.
Biochemistry ; 57(5): 827-838, 2018 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-29278326

RESUMO

Deleterious mutations in the serine lipase DDHD2 are a causative basis of complex hereditary spastic paraplegia (HSP, subtype SPG54) in humans. We recently found that DDHD2 is a principal triglyceride hydrolase in the central nervous system (CNS) and that genetic deletion of this enzyme in mice leads to ectopic lipid droplet (LD) accumulation in neurons throughout the brain. Nonetheless, how HSP-related mutations in DDHD2 relate to triglyceride metabolism and LD formation remains poorly understood. Here, we have characterized a set of HSP-related mutations in DDHD2 and found that they disrupt triglyceride hydrolase activity in vitro and impair the capacity of DDHD2 to protect cells from LD accumulation following exposure to free fatty acid, an outcome that was also observed with a DDHD2-selective inhibitor. We furthermore isolated and characterized LDs from brain tissue of DDHD2-/- mice, revealing that they contain both established LD-associated proteins identified previously in other organs and CNS-enriched proteins, including several proteins with genetic links to human neurological disease. These data, taken together, indicate that the genetic inactivation of DDHD2, as caused by HSP-associated mutations, substantially perturbs lipid homeostasis and the formation and content of LDs, underscoring the importance of triglyceride metabolism for normal CNS function and the key role that DDHD2 plays in this process.


Assuntos
Proteínas Associadas a Gotículas Lipídicas/análise , Gotículas Lipídicas/química , Proteínas do Tecido Nervoso/fisiologia , Fosfolipases/fisiologia , Animais , Química Encefálica , Domínio Catalítico/efeitos dos fármacos , Ácidos Graxos/metabolismo , Homeostase , Humanos , Camundongos , Camundongos Knockout , Microscopia Confocal , Mutagênese Sítio-Dirigida , Proteínas do Tecido Nervoso/antagonistas & inibidores , Proteínas do Tecido Nervoso/genética , Especificidade de Órgãos , Fosfolipases/antagonistas & inibidores , Fosfolipases/genética , Fosfolipases A1/deficiência , Proteínas Recombinantes/metabolismo , Paraplegia Espástica Hereditária/genética , Triglicerídeos/metabolismo
3.
Proc Natl Acad Sci U S A ; 111(41): 14924-9, 2014 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-25267624

RESUMO

Complex hereditary spastic paraplegia (HSP) is a genetic disorder that causes lower limb spasticity and weakness and intellectual disability. Deleterious mutations in the poorly characterized serine hydrolase DDHD2 are a causative basis for recessive complex HSP. DDHD2 exhibits phospholipase activity in vitro, but its endogenous substrates and biochemical functions remain unknown. Here, we report the development of DDHD2(-/-) mice and a selective, in vivo-active DDHD2 inhibitor and their use in combination with mass spectrometry-based lipidomics to discover that DDHD2 regulates brain triglycerides (triacylglycerols, or TAGs). DDHD2(-/-) mice show age-dependent TAG elevations in the central nervous system, but not in several peripheral tissues. Large lipid droplets accumulated in DDHD2(-/-) brains and were localized primarily to the intracellular compartments of neurons. These metabolic changes were accompanied by impairments in motor and cognitive function. Recombinant DDHD2 displays TAG hydrolase activity, and TAGs accumulated in the brains of wild-type mice treated subchronically with a selective DDHD2 inhibitor. These findings, taken together, indicate that the central nervous system possesses a specialized pathway for metabolizing TAGs, disruption of which leads to massive lipid accumulation in neurons and complex HSP syndrome.


Assuntos
Lipase/metabolismo , Fosfolipases A1/metabolismo , Paraplegia Espástica Hereditária/enzimologia , Animais , Encéfalo/metabolismo , Encéfalo/ultraestrutura , Cognição , Ativação Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Deleção de Genes , Marcação de Genes , Células HEK293 , Humanos , Lipase/antagonistas & inibidores , Gotículas Lipídicas/metabolismo , Gotículas Lipídicas/ultraestrutura , Locomoção , Camundongos Endogâmicos C57BL , Neurônios/metabolismo , Fosfolipases , Fosfolipases A1/antagonistas & inibidores , Fosfolipases A1/deficiência , Reprodutibilidade dos Testes , Paraplegia Espástica Hereditária/genética , Triglicerídeos/metabolismo
4.
FEBS Lett ; 584(21): 4389-95, 2010 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-20932832

RESUMO

Mammals have three members of the intracellular phospholipase A(1) protein family (phosphatidic acid preferring-phospholipase A(1), p125, and KIAA0725p). In this study, we showed that KIAA0725p is localized in the Golgi, and is rapidly cycled between the Golgi and cytosol. Catalytic activity is important for targeting of KIAA0725p to Golgi membranes. RNA interference experiments suggested that KIAA0725p contributes to efficient membrane trafficking from the Golgi apparatus to the plasma membrane, but is not involved in brefeldin A-induced Golgi-to-endoplasmic reticulum retrograde transport.


Assuntos
Membrana Celular/metabolismo , Complexo de Golgi/metabolismo , Fosfolipases A1/metabolismo , Animais , Biocatálise , Brefeldina A/farmacologia , Citosol/metabolismo , Retículo Endoplasmático/efeitos dos fármacos , Retículo Endoplasmático/metabolismo , Técnicas de Silenciamento de Genes , Células HeLa , Humanos , N-Acetil-Lactosamina Sintase/metabolismo , Fosfolipases A1/deficiência , Fosfolipases A1/genética , Transporte Proteico/efeitos dos fármacos
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