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Detection of Neu1 Sialidase Activity in Regulating TOLL-like Receptor Activation
Published on: September 7, 2010
Saposins (sap) A and C activate the degradation of galactosylsphingosine
K Harzer1, M Hiraiwa, B C Paton
1Institut für Hirnforschung, Universität Tübingen, D-72070 Tübingen, Germany.
Abstract:
As previously shown for [(3)H-galactosyl]ceramide, the breakdown of [(3)H-galactosyl]sphingosine was reduced in prosaposin-deficient skin fibroblast homogenates. Galactosylsphingosine hydrolysis was also deficient in cell homogenates from Krabbe's disease (beta-galactocerebrosidase-deficient) patients, but not acid beta-galactosidase-deficient patients. Moreover, hydrolysis of galactosylsphingosine in the prosaposin-deficient cell homogenates could be partially restored by adding pure saposin A or C, thereby identifying these saposins as essential facilitators of galactosylsphingosine hydrolysis. By contrast, saposins B and D had little effect on galactosylsphingosine hydrolysis in the prosaposin-deficient cells. The reduced galactosylsphingosine turnover in prosaposin-deficiency suggests that there could be a pathogenetic cerebral accumulation of galactosylsphingosine in this disorder.
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