Perturbation of neuronal cobalamin transport by lysosomal enzyme inhibition
| Autor: | Hongyun Li, Brett Garner, Kalani Ruberu, Hua-Wei Zhao |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2014 |
| Předmět: |
Leupeptins
TCA trichloro acetic acid lcsh:Life lcsh:QR1-502 Mitochondrion Biochemistry lcsh:Microbiology DMEM Dulbecco’s modified Eagle’s medium chemistry.chemical_compound hemic and lymphatic diseases MS methionine synthase AdoCbl adenosyl cobalamin subcellular-fractionation VDAC1 voltage-dependent anion channel 1 chemistry.chemical_classification Neurons leupeptin N-acetyl-L-leucyl-L-leucyl-L-argininal Neurodegeneration neurodegeneration MMCM mitochondrial methylmalonyl-coenzyme A mutase Chloroquine vitamin B12 Cell biology TC transcobalamin mitochondria Vitamin B 12 medicine.anatomical_structure lysosome MeCbl methyl cobalamin Cell fractionation hormones hormone substitutes and hormone antagonists HS human serum TCR transcobalamin receptor Cobalamin transport Biophysics Biological Transport Active Biology Cysteine Proteinase Inhibitors S2 Lysosome Cell Line Tumor Lysosomal-Associated Membrane Protein 2 medicine Humans LAMP2 lysosomal-associated membrane protein 2 Molecular Biology Original Paper Mannose 6-phosphate receptor Leupeptin fungi Cell Biology Cbl cobalamin cpm counts per minute Hcy homocysteine medicine.disease lcsh:QH501-531 enzymes and coenzymes (carbohydrates) chemistry Propionate Lysosomes |
| Zdroj: | Bioscience Reports Bioscience Reports, Vol 34, Iss 1, p e00092 (2014) |
| ISSN: | 1573-4935 0144-8463 |
| Popis: | Cbl (cobalamin) utilization as an enzyme cofactor is dependent on its efficient transit through lysosomes to the cytosol and mitochondria. We have previously proposed that pathophysiological perturbations in lysosomal function may inhibit intracellular Cbl transport with consequences for down-stream metabolic pathways. In the current study, we used both HT1080 fibroblasts and SH-SY5Y neurons to assess the impact that protease inhibitors, chloroquine and leupeptin (N-acetyl-L-leucyl-L-leucyl-L-argininal), have on the distribution of [57Co]Cbl in lysosomes, mitochondria and cytosol. Under standard cell culture conditions the distribution of [57Co]Cbl in both neurons and fibroblasts was ~5% in lysosomes, 14% in mitochondria and 81% in cytosol. Treatment of cells with either 25 μM chloroquine or 40 μM leupeptin for 48 h significantly increased the lysosomal [57Co]Cbl levels, by 4-fold in fibroblasts and 10-fold in neurons, and this was associated with reduced cytosolic and mitochondrial [57Co]Cbl concentrations. Based on Western blotting of LAMP2 in fractions recovered from an OptiPrep density gradient, lysosomal Cbl trapping was associated with an expansion of the lysosomal compartment and an increase in a subpopulation of lysosomes with increased size and density. Moreover, the decreased mitochondrial Cbl that was associated with lysosomal Cbl trapping was correlated with decreased incorporation of [14C] propionate into cellular proteins/macromolecules, indicating an inhibition of Cbl-dependent Mm-CoA (methylmalonyl-coenzyme A) mutase activity. These results add support to the idea that lysosomal dysfunction may significantly impact upon Cbl transport and utilization. Vitamin B12 (cobalamin) passes through lysosomes to function inside the cell. We show that lysosomal enzyme impairment causes lysosomal vitamin B12 trapping. Conditions such as ageing and Alzheimer's disease involve lysosome dysfunction and may similarly suffer from vitamin B12 trapping. |
| Databáze: | OpenAIRE |
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