title: Characterization of acid sphingomyelinase activity in human cerebrospinal fluid.
abstract: BACKGROUND
  As a key enzyme in sphingolipid metabolism, acid sphingomyelinase (ASM) is involved in the regulation of cell fate and signaling via hydrolysis of sphingomyelin to form ceramide. While increased activity of the lysosomal form has been associated with various pathological conditions, there are few studies on secretory ASM limited only to cell models, plasma or serum.
  
  
  METHODS
  An optimized assay based on a fluorescent substrate was applied to measure the ASM activity in cerebrospinal fluid (CSF) collected from mice and from 42 patients who were classified as controls based on normal routine CSF values.
  
  
  RESULTS
  We have detected ASM activity in human CSF, established a sensitive quantitative assay and characterized the enzyme's properties. The enzyme resembles plasmatic ASM including protein stability and Zn(2+)-dependence but the assays differ considerably in the optimal detergent concentration. Significantly increased activities in the CSF of ASM transgenic mice and undetectable levels in ASM knock-out mice prove that the measured ASM activity originates from the ASM-encoding gene SMPD1. CSF localized ASM activities were comparable to corresponding serum ASM levels at their respective optimal reaction conditions, but no correlation was observed. The large variance in ASM activity was independent of sex, age or analyzed routine CSF parameters.
  
  
  CONCLUSIONS
  Human and mouse CSF contain detectable levels of secretory ASM, which are unrelated to serum ASM activities. Further investigations in humans and in animal models will help to elucidate the role of this enzyme in human disease and to assess its value as a potential biomarker for disease type, severity, progress or therapeutic success.
authors: Department of Psychiatry and Psychotherapy, Friedrich-Alexander-University of Erlangen-Nuremberg, Erlangen, Germany. christiane.muehle@uk-erlangen.de
authors: Christiane
authors: C
authors: Mühle
authors: Hagen B
authors: HB
authors: Huttner
authors: Silke
authors: S
authors: Walter
authors: Martin
authors: M
authors: Reichel
authors: Fabio
authors: F
authors: Canneva
authors: Piotr
authors: P
authors: Lewczuk
authors: Erich
authors: E
authors: Gulbins
authors: Johannes
authors: J
authors: Kornhuber
mesh_terms: D000328:Adult; D000818:Animals; D057075:Enzyme Assays / Q000379:methods*; D005260:Female; D005456:Fluorescent Dyes / Q000378:metabolism; D055786:Gene Knockout Techniques; D006801:Humans; D007700:Kinetics; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008875:Middle Aged; D013108:Sphingomyelin Phosphodiesterase / Q000134:cerebrospinal fluid* / Q000172:deficiency / Q000235:genetics / Q000378:metabolism
chemical_list: D005456:Fluorescent Dyes; D013108:Sphingomyelin Phosphodiesterase
references: J Alzheimers Dis. 2011;27(2):259-69
references: 21841258
references: PLoS One. 2011;6(8):e23852
references: 21909365
references: Trends Cardiovasc Med. 2002 Jan;12(1):37-42
references: 11796243
references: Epilepsy Res. 2008 Oct;81(2-3):161-6
references: 18603412
references: Neurobiol Aging. 2004 Mar;25(3):273-81
references: 15123331
references: Biol Pharm Bull. 2004 Nov;27(11):1725-9
references: 15516713
references: Hum Mol Genet. 2000 Aug 12;9(13):1967-76
references: 10942425
references: Biochim Biophys Acta. 2009 Jan;1788(1):178-83
references: 18786504
references: Acta Pharmacol Sin. 2009 Oct;30(10):1454-61
references: 19749786
references: Biochim Biophys Acta. 2006 Dec;1758(12):2016-26
references: 16996023
references: Biochem J. 1981 May 1;195(2):373-82
references: 6274305
references: Am J Physiol Regul Integr Comp Physiol. 2006 Jan;290(1):R11-26
references: 16352856
references: J Inherit Metab Dis. 2007 Oct;30(5):654-63
references: 17632693
references: J Neurosci Methods. 1986 Jul;17(1):63-8
references: 3747592
references: Cell Physiol Biochem. 2010;26(1):9-20
references: 20502000
references: Neuroscience. 2005;130(3):657-66
references: 15590150
references: Alcohol Clin Exp Res. 2011 Oct;35(10):1852-9
references: 21595704
references: Alcohol Clin Exp Res. 2010 Jan;34(1):46-50
references: 19860808
references: J Neuroinflammation. 2012 Jul 02;9:151
references: 22747753
references: J Biol Chem. 2002 Jul 19;277(29):25851-4
references: 12011102
references: J Biol Chem. 1998 Jul 17;273(29):18250-9
references: 9660788
references: J Biol Chem. 1998 Feb 13;273(7):4081-8
references: 9461601
references: PLoS One. 2012;7(4):e35467
references: 22558155
references: J Lipid Res. 2009 Mar;50(3):574-585
references: 18832345
references: J Neural Transm (Vienna). 2009 Sep;116(9):1163-7
references: 19653063
references: J Alzheimers Dis. 2011;24 Suppl 2:127-41
references: 21422517
references: J Biol Chem. 2002 Jul 19;277(29):25847-50
references: 12011103
references: J Alzheimers Dis. 2012;29(3):537-47
references: 22258513
references: Adv Enzyme Regul. 2011;51(1):51-8
references: 21035485
references: J Vis Exp. 2008 Nov 10;(21):
references: 19066529
references: Cell Physiol Biochem. 2010;26(1):1-8
references: 20501999
references: Alzheimers Dement. 2012 Jan;8(1):65-73
references: 22047631
references: Nat Genet. 1995 Jul;10(3):288-93
references: 7670466
references: Mech Ageing Dev. 2001 Jul 15;122(9):895-908
references: 11348657
references: J Invest Dermatol. 1978 Jun;70(6):331-5
references: 25935
references: Biochem J. 2003 Jan 15;369(Pt 2):199-211
references: 12408751
references: Tohoku J Exp Med. 2000 Sep;192(1):61-6
references: 11128869
references: J Neural Transm (Vienna). 2005 Nov;112(11):1583-90
references: 16245071
references: J Biol Chem. 2003 Aug 29;278(35):32744-52
references: 12801930
references: Neurobiol Aging. 2010 Mar;31(3):398-408
references: 18547682