Hydrolysis of sphingosylphosphocholine by neutral sphingomyelinases

Abstract

Sphingosylphosphocholine (SPC), the N-deacylated form of sphingomyelin (SM), is a naturally occurring lipid mediator. However, little is known about the metabolism of SPC. We here report an in vitro assay system for SPC-phospholipase C (PLC). Using this assay system, we demonstrated that nSMase1 and nSMase2, human neutral sphingomyelinases (SMases), are capable of hydrolyzing SPC e⁄ciently under detergent-free conditions. Bacterial and plasmodial neutral SMases also showed SPC-PLC activity. The substrate speci¢c-ity of neutral SMases that hydrolyze SM, SPC, and monoradyl glycerophosphocholine, but not diradyl glycerophosphocholine, suggested that a hydrogen-bond donor at the C-2 or sn-2 position in the substrate is required for recognition by the enzymes. ß 2004 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.

Chromogenic Assay for the Activity of Sphingomyelinase from Bacillus cereus and Its Application to the Enzymatic Hydrolysis of Lysophospholipids

“…Recently, the enzyme activities of nSMase 1 and nSMase 2 toward several phospholipids have been reported. 24) These two nSMases hydrolyzed SM more predominantly than lysoPAF in the presence of Triton X-100 and phosphatidylserine. We found that the hydrolysis of lysoPAF catalyzed by B. cereus SMase was restrained to the same extent as that of lysoPC in the presence of Triton X-100 (data not shown).…”

Bone-related gene profiles in developing calvaria

“…The fifth largest increase was observed for sphingomyelin phosphodiesterase 3 neutral (Smpd3), which is a member of a large superfamily of magnesium-dependent phosphohydrolases. Smpd3 is an enzyme which hydrolyzes sphingosylphosphocholine in the plasma membrane to produce ceramide (Marchesini et al, 2003;Miura et al, 2004). It was originally identified as a brainspecific neutral sphingomylelinase (Hofmann et al, 2000).…”

Upregulation of smpd3 via BMP2 stimulation and Runx2

“…Neutral SMasess are ubiquitously expressed but are expressed at higher levels in the brain and in the embryonic bone growth plate (21). The phenotype of smpd3 −/− mice mimics that of human chondrodysplasia, which manifests as a genetic disorder with clinical heterogeneity (2,12).…”