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Zn 2+ -stimulated Sphingomyelinase Is Secreted by Many Cell Types and Is a Product of the Acid Sphingomyelinase Gene *

Journal of Biological Chemistry, ISSN: 0021-9258, Vol: 271, Issue: 31, Page: 18431-18436
1996
  • 260
    Citations
  • 0
    Usage
  • 55
    Captures
  • 1
    Mentions
  • 0
    Social Media
Metric Options:   Counts1 Year3 Year

Metrics Details

  • Citations
    260
  • Captures
    55
  • Mentions
    1
    • References
      1
      • Wikipedia
        1

Article Description

Mammalian sphingomyelinases have been implicated in many important physiological and pathophysiological processes. Although several mammalian sphingomyelinases have been identified and studied, one of these, an acidic Zn 2+ -stimulated sphingomyelinase (Zn-SMase) originally found in fetal bovine serum, has received little attention since its first and only report 7 years ago. We now show that Zn-SMase activity is secreted by human and murine macrophages, human skin fibroblasts, microglial cells, and several other cells in culture and is markedly up-regulated during differentiation of human monocytes to macrophages. Remarkably, peritoneal macrophages from mice in which the acid SMase gene had been disrupted by homologous recombination secreted no Zn-SMase activity, indicating that this enzyme and the intracellular lysosomal SMase, which is Zn-independent, arise from the same gene. Furthermore, skin fibroblasts from patients with types A and B Niemann-Pick disease, which are known to lack lysosomal SMase activity, also lack Zn-SMase activity in their conditioned media. Chinese hamster ovary cells stably transfected with a cDNA encoding lysosomal SMase massively overexpress both cellular lysosomal SMase and secreted Zn-SMase activities. Thus, Zn-SMase arises independently of alternative splicing, suggesting a post-translational process. In summary, a wide variety of cell types secrete Zn-SMase activity, which arises from the same gene as lysosomal SMase. This secreted enzyme may play roles in physiological and pathophysiological processes involving extracellular sphingomyelin hydrolysis.

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