β-Hexosaminidase over-expression affects lysosomal glycohydrolases expression and glycosphingolipid metabolism in mammalian cells
Lysosomes are not only degrading organelles but also involved in other critical cellular processes. In addition, active lysosomal glycohydrolases have been detected in an extra-lysosomal compartment: the presence of glycohydrolases on the plasma membrane (PM) has been widely demonstrated, and a possible role on the modification of the cell surface glycosphingolipids (GSL) participating in the modulation of cell functions such as cell-to-cell interactions and signal transduction pathways has been proposed. On this basis, the coordinated expression of lysosomal glycohydrolases and their translocation to the PM appear to be crucial for many cellular events. In this paper, we report evidence for the existence of a coordinated mechanism regulating the expression/activity of both lysosomal and PM-associated glycohydrolases. We show that the over-expression of the acidic glycohydrolase β-hexosaminidase α-subunit in mouse NIH/3T3 fibroblasts induces the increased expression of the Hex β-subunit necessary to form the active isoenzyme dimers as well as of other glycohydrolases participating in the GSL catabolism, such as β-galactosidase and β-glucocerebrosidase. More interestingly, this regulatory effect was also extended to the PM-associated hydrolases. In addition, transfected cells displayed a rearrangement of the GSL expression pattern that cannot be simply explained by the increased activity of a single enzyme. These observations clearly indicate that the expression level of metabolically related glycohydrolases is regulated in a coordinated manner and this regulation mechanism also involves the PM-associated isoforms.
KeywordsFibroblasts Glycohydrolases Glycosphingolipid metabolism β-Hexosaminidase over-expression Lysosomes PM-associated hydrolases
High-performance thin layer chromatography
This work was supported by grants from: Fondazione Cassa di Risparmio di Perugia [2010.011.0434]; Azzurra, Associazione Malattie Rare O.N.L.U.S. to G.M.S and COFIN-PRIN 2010–2012 to S.S.
- 11.Mencarelli S, Cavalieri C, Magini A, Tancini B, Basso L, Lemansky P, Hasilik A, Li YT, Chigorno V, Orlacchio A, Emiliani C, Sonnino S (2005) Identification of plasma membrane associated mature beta-hexosaminidase A, active towards GM2 ganglioside, in human fibroblasts. FEBS Lett 579:5501–5506PubMedCrossRefGoogle Scholar
- 32.Martino S, Marconi P, Tancini B, Dolcetta D, De Angelis MG, Montanucci P, Bregola G, Sandhoff K, Bordignon C, Emiliani C, Manservigi R, Orlacchio A (2005) A direct gene transfer strategy via brain internal capsule reverses the biochemical defect in Tay-Sachs disease. Hum Mol Genet 14:2113–2123PubMedCrossRefGoogle Scholar
- 35.Arfi A, Bourgoin C, Basso L, Emiliani C, Tancini B, Chigorno V, Li YT, Orlacchio A, Poenaru L, Sonnino S, Caillaud C (2005) Bicistronic lentiviral vector corrects B-hexosaminidase deficiency in transduced and cross-corrected human Sandhoff fibroblasts. Neurobiol Dis 20:583–593PubMedCrossRefGoogle Scholar
- 39.Magini A, Polchi A, Tancini B, Urbanelli L, Hasilik A, Emiliani C (2011) Glycohydrolases β-hexosaminidase and β-galactosidase are associated with lipid microdomains of Jurkat T-lymphocytes. Biochimie. doi: 10.1016/j.biochi.2011.09.021