Characterization of a Neutral Sphingomyelinase Activity in Human Serum and Plasma
Alterations of sphingolipids and their metabolizing enzymes play a role in various diseases. However, peripheral biomarkers for such changes are limited. Particularly, in the increasingly reported involvement of neutral sphingomyelinase (NSM) with four described isoforms in tissues or cells, a perip...
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| Format: | Article |
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MDPI AG
2023-01-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/24/3/2467 |
| _version_ | 1797624321318846464 |
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| author | Christiane Mühle Johannes Kornhuber |
| author_facet | Christiane Mühle Johannes Kornhuber |
| author_sort | Christiane Mühle |
| collection | DOAJ |
| description | Alterations of sphingolipids and their metabolizing enzymes play a role in various diseases. However, peripheral biomarkers for such changes are limited. Particularly, in the increasingly reported involvement of neutral sphingomyelinase (NSM) with four described isoforms in tissues or cells, a peripheral marker is lacking. We here describe the detection of an NSM activity in human serum and plasma samples which hydrolyses fluorescently labeled sphingomyelin to ceramide in a time- and volume-dependent manner. Reaction rates were linear up to 10 days, and serum volumes above 2 vol-% were inhibitory. Biochemical properties were different from acid sphingomyelinase (ASM) with respect to detergent specificity (sodium deoxycholate), pH profile (pH 7–9), and cation dependence: Serum NSM activity was inhibited by EDTA ≥ 1 µM and restored in EDTA-anticoagulated plasma with the addition of ≥ 100 µM Co<sup>2+</sup>. It was independent of Mg<sup>2+</sup>, the typical cofactor of cellular NSM species, and even inhibited by [Mg<sup>2+</sup>] ≥ 20 mM. Serum NSM activity was not correlated with ASM activity and was independent of sex and age in 24 healthy adults. Since human peripheral NSM activity is very low and activities in rodents are even lower or undetectable, future research should aim to increase the reaction rate and determine the source of this enzymatic activity. The established activity could serve as a future biomarker or therapeutic target in diseases affected by sphingolipid derangements. |
| first_indexed | 2024-03-11T09:40:44Z |
| format | Article |
| id | doaj.art-449f06d84ef0415db78c1bd1d4411bd5 |
| institution | Directory Open Access Journal |
| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-11T09:40:44Z |
| publishDate | 2023-01-01 |
| publisher | MDPI AG |
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| series | International Journal of Molecular Sciences |
| spelling | doaj.art-449f06d84ef0415db78c1bd1d4411bd52023-11-16T16:57:41ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672023-01-01243246710.3390/ijms24032467Characterization of a Neutral Sphingomyelinase Activity in Human Serum and PlasmaChristiane Mühle0Johannes Kornhuber1Department of Psychiatry and Psychotherapy, Universitätsklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, D-91054 Erlangen, GermanyDepartment of Psychiatry and Psychotherapy, Universitätsklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Schwabachanlage 6, D-91054 Erlangen, GermanyAlterations of sphingolipids and their metabolizing enzymes play a role in various diseases. However, peripheral biomarkers for such changes are limited. Particularly, in the increasingly reported involvement of neutral sphingomyelinase (NSM) with four described isoforms in tissues or cells, a peripheral marker is lacking. We here describe the detection of an NSM activity in human serum and plasma samples which hydrolyses fluorescently labeled sphingomyelin to ceramide in a time- and volume-dependent manner. Reaction rates were linear up to 10 days, and serum volumes above 2 vol-% were inhibitory. Biochemical properties were different from acid sphingomyelinase (ASM) with respect to detergent specificity (sodium deoxycholate), pH profile (pH 7–9), and cation dependence: Serum NSM activity was inhibited by EDTA ≥ 1 µM and restored in EDTA-anticoagulated plasma with the addition of ≥ 100 µM Co<sup>2+</sup>. It was independent of Mg<sup>2+</sup>, the typical cofactor of cellular NSM species, and even inhibited by [Mg<sup>2+</sup>] ≥ 20 mM. Serum NSM activity was not correlated with ASM activity and was independent of sex and age in 24 healthy adults. Since human peripheral NSM activity is very low and activities in rodents are even lower or undetectable, future research should aim to increase the reaction rate and determine the source of this enzymatic activity. The established activity could serve as a future biomarker or therapeutic target in diseases affected by sphingolipid derangements.https://www.mdpi.com/1422-0067/24/3/2467ceramidesphingomyelinsphingolipid metabolismenzyme inhibitorsblood biomarkercobalt cofactor |
| spellingShingle | Christiane Mühle Johannes Kornhuber Characterization of a Neutral Sphingomyelinase Activity in Human Serum and Plasma International Journal of Molecular Sciences ceramide sphingomyelin sphingolipid metabolism enzyme inhibitors blood biomarker cobalt cofactor |
| title | Characterization of a Neutral Sphingomyelinase Activity in Human Serum and Plasma |
| title_full | Characterization of a Neutral Sphingomyelinase Activity in Human Serum and Plasma |
| title_fullStr | Characterization of a Neutral Sphingomyelinase Activity in Human Serum and Plasma |
| title_full_unstemmed | Characterization of a Neutral Sphingomyelinase Activity in Human Serum and Plasma |
| title_short | Characterization of a Neutral Sphingomyelinase Activity in Human Serum and Plasma |
| title_sort | characterization of a neutral sphingomyelinase activity in human serum and plasma |
| topic | ceramide sphingomyelin sphingolipid metabolism enzyme inhibitors blood biomarker cobalt cofactor |
| url | https://www.mdpi.com/1422-0067/24/3/2467 |
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