Dataset Information

Acid sphingomyelinase modulates the autophagic process by controlling lysosomal biogenesis in Alzheimer's disease.

ABSTRACT: In Alzheimer's disease (AD), abnormal sphingolipid metabolism has been reported, although the pathogenic consequences of these changes have not been fully characterized. We show that acid sphingomyelinase (ASM) is increased in fibroblasts, brain, and/or plasma from patients with AD and in AD mice, leading to defective autophagic degradation due to lysosomal depletion. Partial genetic inhibition of ASM (ASM(+/-)) in a mouse model of familial AD (FAD; amyloid precursor protein [APP]/presenilin 1 [PS1]) ameliorated the autophagocytic defect by restoring lysosomal biogenesis, resulting in improved AD clinical and pathological findings, including reduction of amyloid-β (Aβ) deposition and improvement of memory impairment. Similar effects were noted after pharmacologic restoration of ASM to the normal range in APP/PS1 mice. Autophagic dysfunction in neurons derived from FAD patient induced pluripotent stem cells (iPSCs) was restored by partial ASM inhibition. Overall, these results reveal a novel mechanism of ASM pathogenesis in AD that leads to defective autophagy due to impaired lysosomal biogenesis and suggests that partial ASM inhibition is a potential new therapeutic intervention for the disease.

SUBMITTER: Lee JK

PROVIDER: S-EPMC4113944 | biostudies-literature | 2014 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Acid sphingomyelinase modulates the autophagic process by controlling lysosomal biogenesis in Alzheimer's disease.

Lee Jong Kil JK Jin Hee Kyung HK Park Min Hee MH Kim Bo-ra BR Lee Phil Hyu PH Nakauchi Hiromitsu H Carter Janet E JE He Xingxuan X Schuchman Edward H EH Bae Jae-sung JS

The Journal of experimental medicine 20140721 8

In Alzheimer's disease (AD), abnormal sphingolipid metabolism has been reported, although the pathogenic consequences of these changes have not been fully characterized. We show that acid sphingomyelinase (ASM) is increased in fibroblasts, brain, and/or plasma from patients with AD and in AD mice, leading to defective autophagic degradation due to lysosomal depletion. Partial genetic inhibition of ASM (ASM(+/-)) in a mouse model of familial AD (FAD; amyloid precursor protein [APP]/presenilin 1 [ ...[more]

PMID: 25049335

Similar Datasets

Project description:BackgroundAutophagy is a major pathway of protein and organelle degradation in the lysosome. Autophagy exists at basal constitutive level and can be induced as a defense mechanism under stress conditions. Molecular relationships between autophagy and inflammation at the periphery were recently evidenced, highlighting a role of autophagy in the regulation of inflammation. Impairment of autophagy (with accumulation of autophagic vacuoles) and substantial inflammation are found in neurodegenerative diseases such as Alzheimer's Disease (AD). However, the links between autophagy and inflammation in AD remain to be determined.MethodsHere, we examined the inflammatory reaction and autophagy in murine tri-cultures of neurons, astrocytes, and microglia. Tri-cultures were exposed to various inflammatory stresses (lipopolysaccharide (LPS), amyloid peptide (A?42) with or without cytokines) for 48 hours. Furthermore, the relationships between inflammation and autophagy were also analyzed in astrocyte- and microglia-enriched cultures. Data for multiple variable comparisons were analyzed by a one-way ANOVA followed by a Newman-keuls' test.ResultsA?42 induced a low inflammation without accumulation of acidic vesicles contrary to moderate or severe inflammation induced by LPS or the cytokine cocktail (IL-1?, TNF-?, and IL-6) or IL-1? alone which led to co-localization of p62 and LC3, two markers of autophagy, with acidic vesicles stained with Lyso-ID Red dye. Moreover, the study reveals a major role of IL-1? in the induction of autophagy in tri-cultures in the presence or absence of A?42. However, the vulnerability of the autophagic process in purified microglia to IL-1? was prevented by A?42.ConclusionThese findings show a close relationship between inflammation and autophagy, in particular a major role of IL-1? in the induction of the microglial autophagy which could be the case in AD. New therapeutic strategies could target inflammasome and autophagy in microglia to maintain its role in the amyloid immunosurveillance.

Project description:BackgroundLysosomal homeostasis and functions are essential for the survival of neural cells. Impaired lysosomal biogenesis and acidification in Alzheimer's disease (AD) pathogenesis leads to proteolytic dysfunction and neurodegeneration. However, the key regulatory factors and mechanisms of lysosomal homeostasis in AD remain poorly understood.MethodsROCK1 expression and its co-localization with LAMP1 and SQSTM1/p62 were detected in post-mortem brains of healthy controls and AD patients. Lysosome-related fluorescence probe staining, transmission electron microscopy and immunoblotting were performed to evaluate the role of ROCK1 in lysosomal biogenesis and acidification in various neural cell types. The interaction between ROCK1 and TFEB was confirmed by surface plasmon resonance and in situ proximity ligation assay (PLA). Moreover, we performed AAV-mediated ROCK1 downregulation followed by immunofluorescence, enzyme-linked immunosorbent assay (ELISA) and behavioral tests to unveil the effects of the ROCK1-TFEB axis on lysosomes in APP/PS1 transgenic mice.ResultsROCK1 level was significantly increased in the brains of AD individuals, and was positively correlated with lysosomal markers and Aβ. Lysosomal proteolysis was largely impaired by the high abundance of ROCK1, while ROCK1 knockdown mitigated the lysosomal dysfunction in neurons and microglia. Moreover, we verified ROCK1 as a previously unknown upstream kinase of TFEB independent of m-TOR or GSK-3β. ROCK1 elevation resulted in abundant extracellular Aβ deposition which in turn bound to Aβ receptors and activated RhoA/ROCK1, thus forming a vicious circle of AD pathogenesis. Genetically downregulating ROCK1 lowered its interference with TFEB, promoted TFEB nuclear distribution, lysosomal biogenesis and lysosome-mediated Aβ clearance, and eventually prevented pathological traits and cognitive deficits in APP/PS1 mice.ConclusionIn summary, our results provide a mechanistic insight into the critical role of ROCK1 in lysosomal regulation and Aβ clearance in AD by acting as a novel upstream serine kinase of TFEB.

Project description:Farber disease is a rare lysosomal storage disorder resulting from acid ceramidase deficiency and subsequent ceramide accumulation. No treatments for Farber disease are clinically available, and affected patients have a severely shortened lifespan. We have recently reported a novel acid ceramidase deficiency model that mirrors the human disease closely. Acid sphingomyelinase is the enzyme that generates ceramide upstream of acid ceramidase in the lysosomes. Using our acid ceramidase deficiency model, we tested if acid sphingomyelinase could be a potential novel therapeutic target for the treatment of Farber disease. A number of functional acid sphingomyelinase inhibitors are clinically available and have been used for decades to treat major depression. Using these as a therapeutic for Farber disease, thus, has the potential to improve central nervous symptoms of the disease as well, something all other treatment options for Farber disease can't achieve so far. As a proof-of-concept study, we first cross-bred acid ceramidase deficient mice with acid sphingomyelinase deficient mice in order to prevent ceramide accumulation. Double-deficient mice had reduced ceramide accumulation, fewer disease manifestations, and prolonged survival. We next targeted acid sphingomyelinase pharmacologically, to test if these findings would translate to a setting with clinical applicability. Surprisingly, the treatment of acid ceramidase deficient mice with the acid sphingomyelinase inhibitor amitriptyline was toxic to acid ceramidase deficient mice and killed them within a few days of treatment. In conclusion, our study provides the first proof-of-concept that acid sphingomyelinase could be a potential new therapeutic target for Farber disease to reduce disease manifestations and prolong survival. However, we also identified previously unknown toxicity of the functional acid sphingomyelinase inhibitor amitriptyline in the context of Farber disease, strongly cautioning against the use of this substance class for Farber disease patients.

Dataset Information

Acid sphingomyelinase modulates the autophagic process by controlling lysosomal biogenesis in Alzheimer's disease.

Publications

Acid sphingomyelinase modulates the autophagic process by controlling lysosomal biogenesis in Alzheimer's disease.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets