Abnormal ganglioside accumulation in cultured fibroblasts from patients with mucolipidosis IV

Bach, Gideon; Cohen, Maimon M.; Kohn, Gertrude

doi:10.1016/0006-291x(75)90526-4

Cited by 75 publications

(48 citation statements)

References 10 publications

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“…According to previous reports, analysis of fibroblasts from MLIV patients by electron microscopy revealed the accumulation of enlarged vacuolar structures that contain mucopolysaccharides and lipids forming characteristic multiconcentric lamellae (Bach et al, 1975;Bach et al, 1977;Crandall et al, 1982;Tellez-Nagel et al, 1976). These enlarged vacuoles are present not only in fibroblasts but in every tissue and organ of MLIV patients, suggesting a general impairment of lysosomal function.…”

Section: Introductionmentioning

confidence: 86%

LAPTMs regulate lysosomal function and interact with mucolipin 1: new clues for understanding mucolipidosis type IV

Vergarajaúregui

Martina

Puertollano

2011

Journal of Cell Science

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SummaryLoss-of-function mutations in mucolipin 1 (MCOLN1) result in mucolipidosis type IV (MLIV), a lysosomal storage disorder characterized by severe mental and psychomotor retardation. MCOLN1 is a lysosomal ion channel that belongs to the transient receptor potential (TRP) superfamily. To better understand the cellular function of MCOLN1, a split-ubiquitin yeast two-hybrid screen was performed with the purpose of revealing new MCOLN1 interaction partners. The screen identified two members of the lysosomeassociated protein transmembrane (LAPTM) family as novel interaction partners of MCOLN1. The binding between MCOLN1 and LAPTM members (LAPTMs) was confirmed by co-immunoprecipitation and yeast two-hybrid assays. In addition, MCOLN1 and LAPTMs extensively colocalize at late endosomes and lysosomes. Overexpression of LAPTM4b caused enlargement of lysosomes and defective lysosomal degradation, indicating that LAPTMs are important for proper lysosomal function. Interestingly, lysosomal swelling induced by LAPTM4b was rescued by expression of MCOLN1, suggesting a functional connection between the two proteins. Finally, depletion of endogenous LAPTMs by siRNA induced accumulation of concentric multi-lamellar structures and electron-dense inclusions that closely resemble the structures found in MLIV cells. Overall, our data provide new insight into the molecular mechanisms of MCOLN1 function and suggest a potential role for LAPTMs in MLIV pathogenesis.

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Section: Introductionmentioning

confidence: 86%

LAPTMs regulate lysosomal function and interact with mucolipin 1: new clues for understanding mucolipidosis type IV

Vergarajaúregui

Martina

Puertollano

2011

Journal of Cell Science

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“…Since the initial description of mannosidosis in 1967 (14), the biochemistry of this disorder has been characterized in several laboratories (1)(2)(3)(9)(10)(11)(12)(13)(14)(15)(16)(17). Heterogeneity has been observed in both the clinical severity and the biochemistry of this entity.…”

Section: Discussionmentioning

confidence: 99%

A New Variant of Mannosidosis with Increased Residual Enzymatic Activity and Mild Clinical Manifestation

Bach

Kohn

Lasch³

et al. 1978

Pediatr Res

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SummaryA partial deficiency of a-mannosidase was found in cultured skin fibroblasts, serum, and extracts of leukocytes in two siblings with mild mental retardation, delayed speech, a suggestion of coarse or full facies, and limited mobility of the large joints. All other lysosomal enzymes tested were within the normal range. Their father demonstrated intermediate a-mannosidase activity. The addition of 2 mM Zn++ caused a 40% increase of the amannosidase activity in cell extracts of both patients and control subjects. pH profiles and Cellogel electrophoresis of the patients' cells indicated 20% residual activity of the acidic a-mannosidase isoenzyme (pH optimum at 4.0), whereas the activity of the isozyme with pH optimum of 6.0 was normal. Increasing substrate concentration (1-10 mM) demonstrated a 4to 5-fold increase in the a~~a r e n t K, of the acidic a-mannosidase in the patients' fibrobiasts. This residual activity, however, was apparently not sufficient for the normal catabolism of mannose-containing molecules, since electron microscopic examination of the culture; fibroblasts demonstrated numerous lysosomal storage bodies. SpeculationThis family supports the concept that mannosidosis is not a homogeneous syndrome but manifests clinical as well as biochemical heterogeneity. The partial activity of acidic a-mannosidase observed in the cultured fibroblasts (approximately 20%) was insufficient for normal catabolism and allows accumulation of amannoside-containing substrates leading to the abnormal phenctype. Nevertheless, this deduction is based on in vitro studies using a synthetic substrate. The observation that Znf+ causes a 40% stimulation of acidic a-mannosidase activity in the patients' cells agrees with previous findings and may be of significance in the treatment of such cases.Mannosidosis, a deficiency of the acidic form of a-mannosidase (EC 3.3.1.24) (14, 15), results in the accumulation of mannose-rich glycosylated compounds in the lysosomes of various tissues (1,12,15) and the excretion of similar compounds in the urine (13,17,18). Clinically, the disorder presents with mildly coarse facies, mild hepatosplenomegaly, skeletal changes, and psychomotor retardation. Human a-mannosidase is separable into two distinct isoenzymes in fibroblasts (16) and three distinct isoenzymes in liver (7). In the liver, two isoenzymes, supposedly lysosomal, have acidic optimal activity (pH 4.0-4.5), whereas the third, a nonlysosomal component, is optimally active at pH 6.0 (7). Patients with mannosidosis demonstrate either a complete deficiency or reduced activity of the acidic isoenzymes. Structural changes in the acidic isoenzyme demonstrate a 25-to 50-fold increase in apparent K, values and high susceptibility to heat inactivation 10 (4, 6, 8), whereas neutral a-mannosidase is normal (7, 11). The normal neutral a-mannosidase activity may explain the differing residual enzyme activities in various tissues of these patients. We wish to describe a family whose clinical and biochemical findings suggest a new variant of ...

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“…Thus, it is unlikely that a corrective effect will remove one group of substances and not the other. Furthermore, previous reports indicated that the correction of lysosomal storage of glycosaminoglycans in mucopolysaccharidoses, which are also the major stored water-soluble substances in MLIV (19), by the deficient enzyme is easily achieved, whereas the correction of lipidic materials is much more difficult to achieve. The use of CQ in this study had only very mild corrective effect and basically it showed an effect of the storage in lower concentrations only with the mild patient, whereas higher concentrations (1-5 M) increased the content of storage vesicles.…”

Section: Discussionmentioning

confidence: 99%

“…Cells were harvested by trypsin (19) and then were washed three times with PBS and fixed for 4 h in 2.5% glutaraldehyde at room temperature. The cells were washed with 0.1 M sodium cacodylate buffer (pH 7.4) and postfixed with 2% osmium tetroxide for 1 h. Then cells were dehydrated in a graded ethanol series and embedded in araldite epon that was allowed to polymerize for 48 h at 60°C.…”

Section: Methodsmentioning

confidence: 99%

Mucolipidosis Type IV: The Effect of Increased Lysosomal pH on the Abnormal Lysosomal Storage

et al. 2009

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Mucolipidosis type IV (MLIV) is a neurodegenerative channelopathy that is caused by the deficiency of TRPML1 activity, a nonselective cation channel. TRPML1 is a lysosomal membrane protein, and thus, MLIV is a lysosomal storage disorder. The basic, specific function of TRPML1 has not been yet clarified. A recent report (Soyombo AA, Tjon-Kon-Sang S, Rbaibi Y, Bashllari E, Bisceglia J, Muallem S, Kiselyov K: J Biol Chem 281:7294 -7301, 2006) indicated that TRPML1 functions as an outwardly proton channel whose function is the prevention of overacidification of these organelles. Thus, in MLIV the lysosomal pH is lower than normal. Furthermore, attempts by these investigators to increase slightly the lysososmal pH with either Nigericin or Chloroquine suggested corrective effect of the abnormal storage in MLIV cells. We investigated this approach using these agents with cultured fibroblasts from severely affected and milder patients. Our data indicated that there was no reduction in the total number of storage vesicles by either agent, although Nigericin resulted in a change in the nature of the storage materials, reducing the presence of lamellated substances (lipids) so that the storage vesicles contained predominantly granulated substances. On the other hand, transfection with the normal MCOLN1 cDNA (the gene coding for TRPML1) resulted in the removal of almost all the storage materials. (Pediatr Res 65: 686-690, 2009)

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Abnormal ganglioside accumulation in cultured fibroblasts from patients with mucolipidosis IV

Cited by 75 publications

References 10 publications

LAPTMs regulate lysosomal function and interact with mucolipin 1: new clues for understanding mucolipidosis type IV

LAPTMs regulate lysosomal function and interact with mucolipin 1: new clues for understanding mucolipidosis type IV

A New Variant of Mannosidosis with Increased Residual Enzymatic Activity and Mild Clinical Manifestation

Mucolipidosis Type IV: The Effect of Increased Lysosomal pH on the Abnormal Lysosomal Storage

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