Abnormal autophagy, ubiquitination, inflammation and apoptosis are dependent upon lysosomal storage and are useful biomarkers of mucopolysaccharidosis VI
© Tessitore et al.; licensee BioMed Central Ltd. 2009
Received: 20 February 2009
Accepted: 16 June 2009
Published: 16 June 2009
Lysosomal storage diseases are characterized by intracellular accumulation of metabolites within lysosomes. Recent evidence suggests that lysosomal storage impairs autophagy resulting in accumulation of polyubiquitinated proteins and dysfunctional mitochondria, ultimately leading to apoptosis. We studied the relationship between lysosome storage and impairment of different intracellular pathways and organelle function in mucopolysaccharidosis VI, which is characterized by accumulation of dermatan sulfate and signs of visceral and skeletal but not cerebral involvement.
We show lysosomal storage, impaired autophagy, accumulation of polyubiquitinated proteins, and mitochondrial dysfunction in fibroblasts from mucopolysaccharidosis VI patients. We observe similar anomalies, along with inflammation and cell death, in association with dermatan sulfate storage in the visceral organs of mucopolysaccharidosis VI rats, but not in their central nervous system where dermatan sulfate storage is absent. Importantly, we show that prevention of dermatan sulfate storage in the mucopolysaccharidosis VI rat visceral organs by gene transfer results in correction of abnormal autophagy, inflammation, and apoptosis, suggesting that dermatan sulfate accumulation impairs lysosomal ability to receive and degrade molecules and organelles from the autophagic pathway, thus leading to cell toxicity.
These results indicate that the non-lysosomal degradation pathways we found activated in mucopolysaccharidosis VI can be both targets of new experimental therapies and biomarkers for follow-up of existing treatments.
Lysosomal storage diseases (LSDs) are severe disorders mostly inherited as autosomal recessive traits in which a lysosomal enzyme defect causes intracellular accumulation of cellular debris within the lysosomes . Little is known about the molecular pathways underlying pathology in LSDs. Degradation and recycling of the building blocks of organelles, proteins, and other cytoplasm components is required for the maintenance of cellular homeostasis . Two general mechanisms are used for large-scale degradation of components of the cytoplasm; short-lived regulatory proteins are degraded via the ubiquitin-proteasome system, and long-lived structures and proteins are targeted to the lysosome by autophagy . Several forms of autophagy have been described . In macroautophagy, henceforth referred to as autophagy, double-membrane vesicles called autophagosomes sequester part of the cytoplasm and then fuse with lysosomes to form hybrid-like organelles called autophagolysosomes . Several proteins are implicated in the formation of autophagosomes. Beclin-1 (BCN1, homologue of yeast ATG6), a protein of the Class III phosphatidylinositol 3 kinase (PI3K) complex, mediates autophagy induction . The microtubule-associated protein 1 light chain 3 (LC3I, homologue of yeast ATG8) is cleaved at its carboxy-terminal, and further modified to the lipid-conjugated LC3II, which is associated to autophagosome membranes [2, 4]. In particular, the ratio between the two forms of LC3 (measured as LC3II/LC3I) correlates with the number of autophagosomes . Perturbation of autophagy (that is, blocking of the fusion of autophagosomes to lysosomes, or an increased number of autophagosomes) results in prolonged nutrient starvation, accumulation of toxic intracellular ubiquitin-related protein aggregations which contain polyubiquitinated proteins, and the critical multifunctional protein p62/A170/sequestosome1 (SQSTM1; hereafter referred to as p62) [5, 6], and dysfunctional mitochondria, ultimately leading to over-production of reactive oxygen species (ROS), inflammation, and cell death . Abnormal autophagy has been described in human skin fibroblasts and mice models of LSDs, such as Niemann-Pick C1 (NPC1) , Danon disease , neuronal ceroid lipofuscinosis 2 , Pompe disease , mucolipidosis type IV [12–14], multiple sulfatase deficiency , mucopolysaccharidosis type IIIA , and GM1 gangliosidosis , indicating that LSDs might be considered as 'disorders of autophagy'. Recently, a model has been proposed suggesting that lysosomal accumulation of undegraded substrates results in defective fusion between autophagosomes and lysosomes [15, 17], which, in turn, leads to a progressive accumulation of poly-ubiquitinated protein aggregates and of dysfunctional mitochondria, eventually leading to cell death [17, 18]. However, the evidence that substrate accumulation is the primary mediator of these anomalies is still missing.
Mucopolysaccharidosis VI (MPS VI), also known as Maroteaux-Lamy syndrome, is caused by deficiency of the lysosomal enzyme N-acetylgalactosamine-4-sulfatase (arylsulfatase B, ARSB) . ARSB hydrolyzes sulfate esters from glycosaminoglycans, mainly dermatan sulfate (DS). ARSB deficiency prevents the sequential degradation of DS leading to its accumulation in various cells and tissues . Clinically, MPS VI is characterized by coarse faces, short stature, dysostosis multiplex, stiffness and functional impairment of joints, hepatosplenomegaly, cardiac valve anomalies and corneal clouding . No clinical signs of central nervous system (CNS) involvement are evident in clinically severe MPS VI . Spontaneous animal models of MPS VI, which closely resemble the human disease, have been described in cats , dogs , and rats . In agreement with the absence of CNS disease in patients, MPS VI animal models do not show behavioral anomalies nor significant DS accumulation in CNS, although some ultrastructural anomalies in MPS VI cat neurons have been reported . Taking advantage of the difference in storage in visceral organs versus CNS of MPS VI and of the possibility to revert storage by gene transfer, we have studied the relationship between storage and autophagy, polyubiquitination, mitochondrial function, inflammation and apoptosis in MPS VI cells and tissues.
Storage accumulation leads to impaired autophagy, abnormal protein ubiquitination and mitochondrial function in human MPS VI cells
Dermatan sulfate accumulation in visceral organs of MPS VI rats results in abnormal autophagy, ubiquitination, mitochondrial function, inflammation, and apoptosis
Despite the differences in the type and the amount of metabolites accumulated in LSDs as well as the cells or tissues where storage occurs, the clinical and pathological manifestations are to some extent similar among LSDs, thus suggesting common mechanisms of disease triggered by different genetic defects [8–16, 30–36]. Identification of critical cellular mediators within these processes may help develop therapies to target them and biomarkers for follow-up of disease progression and therapeutic intervention.
A growing body of evidence suggests that lysosomal storage leads to reduced functionality of lysosomes and consequent autophagy deregulation [15–17]. In this study, we showed impaired autophagy with increased levels of autophagic proteins, increased polyubiquitination and abnormal mitochondrial function in human MPS VI fibroblasts as well as in affected tissues of an MPS VI rodent model. In vivo, this was associated with inflammation and apoptosis. This adds to what has been observed in other LSDs [8–16], where abnormal autophagy has been described, proving that common mechanisms are downstream of different genetic defects in LSDs. The increased amount of autophagosomes in MPS VI fibroblasts might be explained by the inability of lysosomes engulfed with DS to recycle. Indeed, disruption of lysosome function inhibits the fulfillment of autophagy with consequent massive accumulation of autophagosomes. This is indirectly suggested by the slow EGF/EGFR turnover observed in MPS VI fibroblasts. Interestingly, the EGF/EGFR complex is recycled in lysosomes by cathepsin B . Glycosaminoglycans are reported to inhibit cathepsin activity  and cathepsin-activity deficiency results in impaired autophagy .
Alterations in the autophagy-lysosomal degradation pathway have been linked to normal brain aging , to age-related neurodegenerative diseases including Alzheimer's (AD) , Parkinson's (PD) , and Huntington's (HD) diseases  in addition to several LSDs [8–16]. Since deregulation of autophagy is associated with disease progression, it has been speculated that modulating autophagy activity may result in therapeutic efficacy. Enhancement of autophagy (that is, through treatment with rapamycin) may help clear aggregated proteins, as observed in neurodegenerative disorders ; however, because autophagy relies on intact lysosomes for appropriate autophagosome-lysosome fusion, the progressive impairment of lysosome function, as it occurs in LSDs, may reverse any long-term benefits derived from the over-stimulation of autophagy, resulting in nutrient starvation and ultimately in autophagic cell death . Indeed, although induction of autophagy in AD has an initial protective role, long-term over-stimulation of autophagy induces neuronal cell death. Conversely, inhibiting autophagy either pharmacologically or via RNA interference of specific genes significantly attenuates cell death in AD and PD, respectively [40, 45]. Therefore, agents that attenuate autophagy might be similarly useful for treatment of LSDs with increased levels of autophagic markers, that is, NPC, GM1, and now, based on the results of this study, MPS VI.
Although additional studies are required to prove the mechanisms linking autophagy impairment to polyubiquitination anomalies, mitochondrial dysfunction, inflammation, and apoptosis in MPS VI, some hypotheses can be drawn. For instance, mitochondria produce metabolic energy and free radicals (that is, reactive oxygen species (ROS)), serve as biosensors for oxidative stress, and eventually become effectors of apoptosis [12, 46]. In turn the accumulation of fragmented mitochondria we have observed in MPS VI cells and tissues may cause increasing oxidative stress resulting in inflammation, which finally triggers cell death responses as observed in different disorders . Most importantly, our data support a strong association between lysosomal storage and abnormal degradation pathways, inflammation, and apoptosis in vivo. These were present in liver, spleen, and kidney of MPS VI rats where we detect significant DS storage and were absent in the CNS of the same animals where DS storage is absent. In addition, when DS storage is reduced in liver, spleen, and kidney following somatic AAV-mediated gene transfer, levels of autophagic markers, polyubiquitinated proteins, fragmented mitochondria, inflammation, and apoptosis are normalized, demonstrating a therapeutic efficacy on autophagy deregulation and mitochondrial dysfunction in addition to apoptosis and inflammation, as previously described . Similar data have been reported in cartilage and synovial tissues of MPS VI rats, where authors ascribe the onset of inflammation and apoptosis to glycosaminoglycan storage [48, 49]. Moreover, autophagic markers, polyubiquitinated proteins, fragmented mitochondria, inflammation, and apoptosis can be used as biomarkers for follow-up of disease progression. This may be relevant to understanding the clinical history of the disease and to defining the endpoint assessment of therapeutic regimens such as enzyme replacement therapy, bone marrow transplantation, and gene therapy.
In this paper we have studied the relationship between storage and secondary events, such as autophagy, polyubiquitination, mitochondrial function, inflammation, and apoptosis, in MPS VI cells and tissues. We have demonstrated a direct link between substrate storage and abnormal cellular pathways which contribute to the pathophysiology of MPS VI, and we have identified new useful biomarkers for follow-up of disease progression. Our data may help in the development of new therapies which act downstream of the genetic defect in this and other LSDs.
Tissue cultures, animal colonies, and tissue collection
Fibroblasts from MPS VI patients and from normal subjects were grown at 37°C with 5% CO2, in RPMI (Gibco-Invitrogen, Grand Island, NY, USA) and 10% fetal bovine serum (FBS, Sigma-Aldrich, St Louis, MO, USA), supplemented with 100 U/ml penicillin, 100 μg/ml streptomycin (Gibco-Invitrogen, USA). The cell lines were used between passage 2 and 8, and maintained at the same passage number in each experiment performed.
MPS VI rats were maintained at the Cardarelli Hospital's Animal House (Naples, Italy) in an appropriate environment according to the Italian Ministry of Health regulation. Normal and affected offspring were obtained and genotyped as previously described . Tissues were collected from 6-month-old rats in accordance to the Italian Ministry of Health guidelines as previously described . Each tissue collected was divided in pieces and fixed for plastic and paraffin embedding or frozen in dry ice for ARSB activity, GAG quantitative assays, and protein extraction.
Primary antibodies were: rabbit polyclonal anti-LC3 (Novus Biological, Littleton, Colorado, USA), rabbit polyclonal anti-beclin 1 (Santa Cruz Biotechnology, Santa Cruz, California, USA), goat monoclonal anti-LAMP2 (Santa Cruz Biotechnology, USA), mouse monoclonal anti-ubiquitin (Cell Signaling, Danvers, Massachusetts, USA), mouse monoclonal anti-P62/SQSTM1 (BD, Franklin Lakes, New Jersey, USA), mouse monoclonal anti-actin (Sigma-Aldrich, St Louis, Missouri, USA) and rabbit polyclonal anti-COXIV (Cell Signaling, USA). Secondary antibodies were: goat anti-rabbit or anti-mouse conjugated to Alexa Fluor 488 or 594 (Molecular Probes – Invitrogen, Eugene, Oregon, USA). HRP-conjugated anti-mouse or anti-rabbit IgG (Amersham, Freiburg, Germany); biotinylated donkey anti-rabbit (Jackson ImmunoReasearch, West Grove, Pennsylvania, USA).
Protein extraction and western blot analysis
Cells were lysed in cold lysis buffer (50 mM Tris-HCl, pH 7.5; 150 mM NaCl; 0.5% DOC; 0.5% NP-40; 2% sodium azide) in the presence of protease (Roche Diagnostics, Mannheim, Germany) and phosphatase (cocktails I and II by Sigma-Aldrich, St Louis, Missouri, USA) inhibitors for 30 min on ice. Tissue samples (50 μg) were homogenized in 3 volumes of lysis buffer and proteins were quantified using the BCA protein assay reagent kit (Pierce Chemical Co, Rockford, Illinois, USA) according to the manufacturer's instructions. Primary and (HRP)-conjugated antibodies were diluted in 5% milk. Bands were visualized using the ECL detection reagent (Pierce Chemical Co, USA).
A Leica inverted DMIRE2 epifluorescence microscope equipped with a Leica laser-scanning confocal image system TCS SP2 AOBS (Leica Microsystems, Heidelberg, Germany) was used for data acquisition. Samples were excited with a 488 nm Ar laser and 594 nm He-Ne laser. Samples were vertically scanned from the bottom coverslip with a total depth of 50 mm and a 63× (1.32 NA) HP PLAPO oil-immersion objective. A total of 10 z-line scans with a step distance of 0.2 mm was collected and maximum intensity projections were generated with Leica Confocal Software (Leica Microsystems, Wetzlar, Germany).
EGF loading, time-lapse microscopy and immuno-fluorescent analysis
For time-lapse microscopy, skin fibroblasts from normal and MPS VI patients were plated in 35-mm glass-bottom dishes (Willco BV, Amsterdam, the Netherlands) and were incubated at 37°C in 5% CO2 for 16 h, after which they where starved for 2 h with no-serum medium. Following starvation, cells were loaded with 1 μg of Alexa Fluor 488-labeled EGF (Molecular Probes, Invitrogen, USA) and 0.1 μM LysoTacker Red DND-99 (Molecular Probes, Invitrogen, USA) for 1 h at 4°C. After incubation, cells were washed three times with 1 × PBS and medium was replaced with fresh 10% FBS medium. Cells were mounted on Leica AF6000 LX multiposition advanced fluorescence imaging and live cell analysis system (Leica Microsystems, Wetzlar, Germany). The live imaging was performed using an inverted microscope system (Leica DMI6000; Leica, Heidelberg, Germany) equipped with environment control boxes and digital camera (CCD). Images were acquired in fluorescence (GFP and RFP) and transmission (DIC) channels with a 63× glycerin-immersion objective. Usually, stacks about 10 μm thick, composed of sections separated by 0.22 μm, were taken every 15 min during an average period of 24 h. To avoid fading of the fluorescence, the intensity levels were fixed at less than position 2. The 4D captured images thus obtained were deconvoluted using the blind algorithm and adjusted using the brightness switch implemented in the software package AF6000 (Leica, Heidelberg, Germany). Maximum intensity projection of Z-stacks was done for 4D images. Online material (Additional files 1 and 2) contains live-cell imaging.
For immuno-fluorescent microscopy, skin fibroblasts from normal and MPS VI patients were plated in chamber slides (LabTek International, Naperville, Illinois, USA) and loaded with 1 μg of Alexa Fluor 488-labeled EGF (Molecular Probes, Invitrogen, USA) as described above. After washing, 10% FBS fresh medium was added onto the cells, which were incubated at 37°C in 5% CO2, until fixed at different time points with 4% PFA and mounted with Vectashield with DAPI (Vector Laboratories, Burlingame, California, USA).
Mitochondrial membrane potential measurements
PBS-washed 1 × 106 cells were incubated in 1.3 nM DiOC6 (Sigma-Aldrich, St Louis, Missouri, USA) and 1 mg/ml propidium iodide (PI, Sigma-Aldrich, St Louis, Missouri, USA) for 15 min at 37°C. After washing, cells were suspended in 1 ml PBS (pH 7.4) and were subsequently analyzed using flow cytometry. PI was used as counterstain to exclude dead cells from the analyses. At least 10,000 cells in both normal and MPS VI were analyzed for each sample. The experiments were performed in triplicate, and all statistical analyses were performed using Stat-View 5.0 (Statsoft, Tulsa, Oklahoma, USA).
Assay of proteasome activity
20S proteasome activity was assayed on total lysates of cultured fibroblasts and rat tissues (liver, spleen, kidney, and brain) using the Chemicon (Temecula, California, USA) assay kit, according to the manufacturer's recommended protocol.
Semi-thin sections and immuno-histochemistry
For semi-thin sections, tissues were collected and fixed in 2.5% PFA and 2% glutaraldehyde for 12 h; post-fixed in osmium tetroxide, block stained with 1% uranyl acetate, dehydrated in ethanol, and embedded in plastic. Semi-thin sections (1 μm thick) were stained with 0.1% toluidine blue (Fisher Scientific, Pittsburgh, Pennslyvania, USA). For immuno-histochemistry, tissues were fixed in 4% PFA for 12 h and embedded in paraffin (Sigma-Aldrich, St Louis, Missouri, USA) after their dehydration with a 70% to 100% ethanol gradient. Finally, the tissues were sectioned to 5 μm serial sections on a microtome. CD68 staining was performed as previously described .
Electron microscopy analysis
Animal tissues (brains and livers) were fixed with 1% glutaraldehyde, washed, stained with uranylacetate and OsO4, dehydrated in ethanol and embedded in Epon. Resin blocks were sectioned using Ultracut UCT ultramicrotome (Leica Microsystems, Wetzlar, Germany). EM images were acquired from thin sections under a Philips Tecnai-12 electron microscope (Philips, Eindhoven, the Netherlands) using an ULTRA VIEW CCD digital camera (Soft Imaging Systems GmbH, Münster, Germany).
Quantitative analysis of GAG accumulation in tissues and urine
The urine and the protein extracts were assayed with the dimethylmethylene blue-based spectrophotometry of glycosaminoglycans. Briefly, tissues were homogenized in water and centrifuged. After protein quantification, 10 μg of protein extracts or 5 μl of urine were used for the colorimetric assay as previously described . The samples were read at 520 nm and the GAG concentrations were determined using the dermatan sulfate standard curve (Sigma-Aldrich, St Louis, Missouri, USA). Tissue GAG was expressed as μg GAG/mg protein.
TUNEL assay was performed on 5-μm fixed liver sections. Apoptotic cells were detected by using the ApopTag In Situ Apoptosis Detection Kit (Chemicon-Millipore, Temecula, California, USA), as previously described .
Data were analyzed by one-way ANOVA (analysis of variance) and are expressed as the mean ± standard error. For all statistical testing, a P value less than 0.05 was considered significant.
analysis of variance
central nervous system
Epidermal Growth Factor
Epidermal Growth Factor Receptor
lysosome-associated membrane protein-2
lysosomal storage disease
- MPS VI:
reactive oxygen species.
We thank the Telethon Electron Microscopy Core Facility (TeEMCoF) and Dr Roman Polishchuk, Department of Cell Biology and Oncology, Consorzio Mario Negri Sud, Santa Maria Imbaro, Chieti, Italy for performing the electron microscopy; Dr Laura Pisapia and Dr Pasquale Barra, Institute of Genetics and Biophysics, Naples, Italy for FACS analysis; Maurizio Di Tommaso for technical support with the rat colony and the TIGEM Bioinformatics and AAV Vector Cores. MPS VI fibroblasts were provided by the Telethon Cell line and DNA Bank from Patients with Genetic Diseases (Dr Mirella Filocamo, Gaslini Hospital Genoa, Italy) supported by the Telethon Foundation (Telethon grant GTF04002). We are grateful to Professor Andrea Ballabio, Dr Graciana Diez-Roux, and Dr Carmine Settembre for helpful discussion and for critically reviewing the manuscript.
This work was supported by Telethon Grant TIGEM P33, the EC-FP6-projects LSHB-CT-2005-512146 DiMI and 018933 Clinigene from the European Community, grant PRIN 2006064337 from the Italian Ministry of University and Research, grant Regione Campania L.R. n. 5/02 and the European Union, 7th Frame Program 'Euclyd – a European Consortium for Lysosomal Storage Diseases' (health F2/2008 grant agreement 201678 to G.A.).
- Desnick RJ, Schuchman EH: Enzyme replacement and enhancement therapies: lessons from lysosomal disorders. Nat Rev Genet. 2002, 3: 954-966.View ArticlePubMedGoogle Scholar
- Klionsky DJ, Emr SD: Autophagy as a regulated pathway of cellular degradation. Science. 2000, 290: 1717-1721.PubMed CentralView ArticlePubMedGoogle Scholar
- Klionsky DJ, Cuervo AM, Seglen PO: Methods for monitoring autophagy from yeast to human. Autophagy. 2007, 3: 181-206.View ArticlePubMedGoogle Scholar
- Kabeya Y, Mizushima N, Ueno T, Yamamoto A, Kirisako T, Noda T, Kominami E, Ohsumi Y, Yoshimori T: LC3, a mammalian homologue of yeast Apg8p, is localized in autophagosome membranes after processing. Embo J. 2000, 19: 5720-5728.PubMed CentralView ArticlePubMedGoogle Scholar
- Komatsu M, Waguri S, Koike M, Sou YS, Ueno T, Hara T, Mizushima N, Iwata J, Ezaki J, Murata S, Hamazaki J, Nishito Y, Iemura S, Natsume T, Yanagawa T, Uwayama J, Warabi E, Yoshida H, Ishii T, Kobayashi A, Yamamoto M, Yue Z, Uchiyama Y, Kominami E, Tanaka K: Homeostatic levels of p62 control cytoplasmic inclusion body formation in autophagy-deficient mice. Cell. 2007, 131: 1149-1163.View ArticlePubMedGoogle Scholar
- Zatloukal K, Stumptner C, Fuchsbichler A, Heid H, Schnoelzer M, Kenner L, Kleinert R, Prinz M, Aguzzi A, Denk H: p62 Is a common component of cytoplasmic inclusions in protein aggregation diseases. Am J Pathol. 2002, 160: 255-263.PubMed CentralView ArticlePubMedGoogle Scholar
- Boya P, Gonzalez-Polo RA, Casares N, Perfettini JL, Dessen P, Larochette N, Metivier D, Meley D, Souquere S, Yoshimori T, Pierron G, Codogno P, Kroemer G: Inhibition of macroautophagy triggers apoptosis. Mol Cell Biol. 2005, 25: 1025-1040.PubMed CentralView ArticlePubMedGoogle Scholar
- Pacheco CD, Kunkel R, Lieberman AP: Autophagy in Niemann-Pick C disease is dependent upon Beclin-1 and responsive to lipid trafficking defects. Hum Mol Genet. 2007, 16: 1495-1503.View ArticlePubMedGoogle Scholar
- Tanaka Y, Guhde G, Suter A, Eskelinen EL, Hartmann D, Lullmann-Rauch R, Janssen PM, Blanz J, von Figura K, Saftig P: Accumulation of autophagic vacuoles and cardiomyopathy in LAMP-2-deficient mice. Nature. 2000, 406: 902-906.View ArticlePubMedGoogle Scholar
- Koike M, Shibata M, Waguri S, Yoshimura K, Tanida I, Kominami E, Gotow T, Peters C, von Figura K, Mizushima N, Saftig P, Uchiyama Y: Participation of autophagy in storage of lysosomes in neurons from mouse models of neuronal ceroid-lipofuscinoses (Batten disease). Am J Pathol. 2005, 167: 1713-1728.PubMed CentralView ArticlePubMedGoogle Scholar
- Fukuda T, Ewan L, Bauer M, Mattaliano RJ, Zaal K, Ralston E, Plotz PH, Raben N: Dysfunction of endocytic and autophagic pathways in a lysosomal storage disease. Ann Neurol. 2006, 59: 700-708.View ArticlePubMedGoogle Scholar
- Jennings JJ, Zhu JH, Rbaibi Y, Luo X, Chu CT, Kiselyov K: Mitochondrial aberrations in mucolipidosis type IV. J Biol Chem. 2006, 281: 39041-39050.View ArticlePubMedGoogle Scholar
- Vergarajauregui S, Connelly PS, Daniels MP, Puertollano R: Autophagic dysfunction in mucolipidosis type IV patients. Hum Mol Genet. 2008, 17: 2723-37.PubMed CentralView ArticlePubMedGoogle Scholar
- Vergarajauregui S, Puertollano R: Mucolipidosis type IV: the importance of functional lysosomes for efficient autophagy. Autophagy. 2008, 4: 832-34.PubMed CentralView ArticlePubMedGoogle Scholar
- Settembre C, Fraldi A, Jahreiss L, Spampanato C, Venturi C, Medina D, de Pablo R, Tacchetti C, Rubinsztein DC, Ballabio A: A block of autophagy in lysosomal storage disorders. Hum Mol Genet. 2008, 17: 119-129.View ArticlePubMedGoogle Scholar
- Takamura A, Higaki K, Kajimaki K, Otsuka S, Ninomiya H, Matsuda J, Ohno K, Suzuki Y, Nanba E: Enhanced autophagy and mitochondrial aberrations in murine G(M1)-gangliosidosis. Biochem Biophys Res Commun. 2008, 367: 616-622.View ArticlePubMedGoogle Scholar
- Settembre C, Fraldi A, Rubinsztein DC, Ballabio A: Lysosomal storage diseases as disorders of autophagy. Autophagy. 2008, 4: 113-114.View ArticlePubMedGoogle Scholar
- Kiselyov K, Jennigs JJ, Rbaibi Y, Chu CT: Autophagy, mitochondria and cell death in lysosomal storage diseases. Autophagy. 2007, 3: 259-262.PubMed CentralView ArticlePubMedGoogle Scholar
- Neufeld E, Muenzer J: The mucopolysaccharidoses. The Metabolic and Molecular Basis of Inherited Disease. Edited by: Scriver CR, Beaudet AL, Sly WS, Valle D. 2001, New York: McGraw-Hill, 3421-3454. 8Google Scholar
- Hopwood JJ, Morris CP: The mucopolysaccharidoses. Diagnosis, molecular genetics and treatment. Mol Biol Med. 1990, 7: 381-404.PubMedGoogle Scholar
- Jezyk PF, Haskins ME, Patterson DF, Mellman WJ, Greenstein M: Mucopolysaccharidosis in a cat with arylsulfatase B deficiency: a model of Maroteaux-Lamy syndrome. Science. 1977, 198: 834-836.View ArticlePubMedGoogle Scholar
- Neer TM, Dial SM, Pechman R, Wang P, Oliver JL, Giger U: Clinical vignette. Mucopolysaccharidosis VI in a miniature pinscher. J Vet Intern Med. 1995, 9: 429-433.View ArticlePubMedGoogle Scholar
- Yoshida M, Noguchi J, Ikadai H, Takahashi M, Nagase S: Arylsulfatase B-deficient mucopolysaccharidosis in rats. J Clin Invest. 1993, 91: 1099-1104.PubMed CentralView ArticlePubMedGoogle Scholar
- Walkley SU, Thrall MA, Haskins ME, Mitchell TW, Wenger DA, Brown DE, Dial S, Seim H: Abnormal neuronal metabolism and storage in mucopolysaccharidosis type VI (Maroteaux-Lamy) disease. Neuropathol Appl Neurobiol. 2005, 31: 536-544.View ArticlePubMedGoogle Scholar
- Alwan HA, van Zoelen EJ, van Leeuwen JE: Ligand-induced lysosomal epidermal growth factor receptor (EGFR) degradation is preceded by proteasome-dependent EGFR de-ubiquitination. J Biol Chem. 2003, 278: 35781-35790.View ArticlePubMedGoogle Scholar
- Authier F, Metioui M, Bell AW, Mort JS: Negative regulation of epidermal growth factor signaling by selective proteolytic mechanisms in the endosome mediated by cathepsin B. J Biol Chem. 1999, 274: 33723-33731.View ArticlePubMedGoogle Scholar
- Macouillard-Poulletier de G, Belaud-Rotureau MA, Voisin P, Leducq N, Belloc F, Canioni P, Diolez P: Flow cytometric analysis of mitochondrial activity in situ: application to acetylceramide-induced mitochondrial swelling and apoptosis. Cytometry. 1998, 33: 333-339.View ArticleGoogle Scholar
- Boland B, Nixon RA: Neuronal macroautophagy: from development to degeneration. Mol Aspects Med. 2006, 27: 503-519.View ArticlePubMedGoogle Scholar
- Eskelinen EL: Fine structure of the autophagosome. Methods Mol Biol. 2008, 445: 11-28.View ArticlePubMedGoogle Scholar
- Tessitore A, Faella A, O'Malley T, Cotugno G, Doria M, Kunieda T, Matarese G, Haskins M, Auricchio A: Biochemical, pathological, and skeletal improvement of mucopolysaccharidosis VI after gene transfer to liver but not to muscle. Mol Ther. 2008, 16: 30-37.View ArticlePubMedGoogle Scholar
- Jeyakumar M, Thomas R, Elliot-Smith E, Smith DA, Spoel van der AC, d'Azzo A, Perry VH, Butters TD, Dwek RA, Platt FM: Central nervous system inflammation is a hallmark of pathogenesis in mouse models of GM1 and GM2 gangliosidosis. Brain. 2003, 126: 974-987.View ArticlePubMedGoogle Scholar
- Mizukami H, Mi Y, Wada R, Kono M, Yamashita T, Liu Y, Werth N, Sandhoff R, Sandhoff K, Proia RL: Systemic inflammation in glucocerebrosidase-deficient mice with minimal glucosylceramide storage. J Clin Invest. 2002, 109: 1215-1221.PubMed CentralView ArticlePubMedGoogle Scholar
- Ohmi K, Greenberg DS, Rajavel KS, Ryazantsev S, Li HH, Neufeld EF: Activated microglia in cortex of mouse models of mucopolysaccharidoses I and IIIB. Proc Natl Acad Sci USA. 2003, 100: 1902-1907.PubMed CentralView ArticlePubMedGoogle Scholar
- Sano R, Tessitore A, Ingrassia A, d'Azzo A: Chemokine-induced recruitment of genetically modified bone marrow cells into the CNS of GM1-gangliosidosis mice corrects neuronal pathology. Blood. 2005, 106: 2259-2268.PubMed CentralView ArticlePubMedGoogle Scholar
- Settembre C, Annunziata I, Spampanato C, Zarcone D, Cobellis G, Nusco E, Zito E, Tacchetti C, Cosma MP, Ballabio A: Systemic inflammation and neurodegeneration in a mouse model of multiple sulfatase deficiency. Proc Natl Acad Sci USA. 2007, 104: 4506-4511.PubMed CentralView ArticlePubMedGoogle Scholar
- Wada R, Tifft CJ, Proia RL: Microglial activation precedes acute neurodegeneration in Sandhoff disease and is suppressed by bone marrow transplantation. Proc Natl Acad Sci USA. 2000, 97: 10954-10959.PubMed CentralView ArticlePubMedGoogle Scholar
- Li Z, Yasuda Y, Li W, Bogyo M, Katz N, Gordon RE, Fields GB, Bromme D: Regulation of collagenase activities of human cathepsins by glycosaminoglycans. J Biol Chem. 2004, 279: 5470-5479.View ArticlePubMedGoogle Scholar
- Boland B, Kumar A, Lee S, Platt FM, Wegiel J, Yu WH, Nixon RA: Autophagy induction and autophagosome clearance in neurons: relationship to autophagic pathology in Alzheimer's disease. J Neurosci. 2008, 28: 6926-6937.PubMed CentralView ArticlePubMedGoogle Scholar
- Cuervo AM: Autophagy: in sickness and in health. Trends Cell Biol. 2004, 14: 70-77.View ArticlePubMedGoogle Scholar
- Yu WH, Cuervo AM, Kumar A, Peterhoff CM, Schmidt SD, Lee JH, Mohan PS, Mercken M, Farmery MR, Tjernberg LO, Jiang Y, Duff K, Uchiyama Y, Naslund J, Mathews PM, Cataldo AM, Nixon RA: Macroautophagy – a novel Beta-amyloid peptide-generating pathway activated in Alzheimer's disease. J Cell Biol. 2005, 171: 87-98.PubMed CentralView ArticlePubMedGoogle Scholar
- Webb JL, Ravikumar B, Atkins J, Skepper JN, Rubinsztein DC: Alpha-Synuclein is degraded by both autophagy and the proteasome. J Biol Chem. 2003, 278: 25009-25013.View ArticlePubMedGoogle Scholar
- Ravikumar B, Rubinsztein DC: Role of autophagy in the clearance of mutant huntingtin: a step towards therapy?. Mol Aspects Med. 2006, 27: 520-527.View ArticlePubMedGoogle Scholar
- Berger Z, Ravikumar B, Menzies FM, Oroz LG, Underwood BR, Pangalos MN, Schmitt I, Wullner U, Evert BO, O'Kane CJ, Rubinsztein DC: Rapamycin alleviates toxicity of different aggregate-prone proteins. Hum Mol Genet. 2006, 15: 433-442.View ArticlePubMedGoogle Scholar
- Baehrecke EH: Autophagy: dual roles in life and death?. Nat Rev Mol Cell Biol. 2005, 6: 505-510.View ArticlePubMedGoogle Scholar
- Malagelada C, Ryu EJ, Biswas SC, Jackson-Lewis V, Greene LA: RTP801 is elevated in Parkinson brain substantia nigral neurons and mediates death in cellular models of Parkinson's disease by a mechanism involving mammalian target of rapamycin inactivation. J Neurosci. 2006, 26: 9996-10005.View ArticlePubMedGoogle Scholar
- Terman A, Gustafsson B, Brunk UT: Autophagy, organelles and ageing. J Pathol. 2007, 211: 134-143.View ArticlePubMedGoogle Scholar
- Mancuso C, Scapagini G, Curro D, Giuffrida Stella AM, De Marco C, Butterfield DA, Calabrese V: Mitochondrial dysfunction, free radical generation and cellular stress response in neurodegenerative disorders. Front Biosci. 2007, 12: 1107-1123.View ArticlePubMedGoogle Scholar
- Simonaro CM, D'Angelo M, Haskins ME, Schuchman EH: Joint and bone disease in mucopolysaccharidoses VI and VII: identification of new therapeutic targets and biomarkers using animal models. Pediatr Res. 2005, 57: 701-707.View ArticlePubMedGoogle Scholar
- Simonaro CM, D'Angelo M, He X, Eliyahu E, Shtraizent N, Haskins ME, Schuchman EH: Mechanism of glycosaminoglycan-mediated bone and joint disease: implications for the mucopolysaccharidoses and other connective tissue diseases. Am J Pathol. 2008, 172: 112-122.PubMed CentralView ArticlePubMedGoogle Scholar
This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.