Neutral Sphingomyelinase-3 Mediates TNF-Stimulated Oxidant Activity in Skeletal Muscle

Authors

Jennifer S. Moylan, University of KentuckyFollow
Jeffrey D. Smith, University of KentuckyFollow
Erin M. Wolf Horrell, University of Kentucky
Julie B. McLean, University of Kentucky
Gergana M. Deevska, University of KentuckyFollow
Mark R. Bonnell, University of Kentucky
Mariana N. Nikolova‑Karakashian, University of KentuckyFollow
Michael B. Reid, University of KentuckyFollow

Abstract

AIMS: Sphingolipid and oxidant signaling affect glucose uptake, atrophy, and force production of skeletal muscle similarly and both are stimulated by tumor necrosis factor (TNF), suggesting a connection between systems. Sphingolipid signaling is initiated by neutral sphingomyelinase (nSMase), a family of agonist-activated effector enzymes. Northern blot analyses suggest that nSMase3 may be a striated muscle-specific nSMase. The present study tested the hypothesis that nSMase3 protein is expressed in skeletal muscle and functions to regulate TNF-stimulated oxidant production.

RESULTS: We demonstrate constitutive nSMase activity in skeletal muscles of healthy mice and humans and in differentiated C2C12 myotubes. nSMase3 (Smpd4 gene) mRNA is highly expressed in muscle. An nSMase3 protein doublet (88 and 85 kD) is derived from alternative mRNA splicing of exon 11. The proteins partition differently. The full-length 88 kD isoform (nSMase3a) fractionates with membrane proteins that are resistant to detergent extraction; the 85 kD isoform lacking exon 11 (nSMase3b) is more readily extracted and fractionates with detergent soluble membrane proteins; neither variant is detected in the cytosol. By immunofluorescence microscopy, nSMase3 resides in both internal and sarcolemmal membranes. Finally, myotube nSMase activity and cytosolic oxidant activity are stimulated by TNF. Both if these responses are inhibited by nSMase3 knockdown.

INNOVATION: These findings identify nSMase3 as an intermediate that links TNF receptor activation, sphingolipid signaling, and skeletal muscle oxidant production.

CONCLUSION: Our data show that nSMase3 acts as a signaling nSMase in skeletal muscle that is essential for TNF-stimulated oxidant activity.

Document Type

Article

Publication Date

7-30-2014

Notes/Citation Information

Published in Redox Biology, v. 2, p. 910-920.

Published by Elsevier B. V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/).

Digital Object Identifier (DOI)

http://dx.doi.org/10.1016/j.redox.2014.07.006

Funding Information

This work was supported by NIH,USA (3R01AR055974,R01AR062083,and T32 CA165990).

Repository Citation

Moylan, Jennifer S.; Smith, Jeffrey D.; Wolf Horrell, Erin M.; McLean, Julie B.; Deevska, Gergana M.; Bonnell, Mark R.; Nikolova‑Karakashian, Mariana N.; and Reid, Michael B., "Neutral Sphingomyelinase-3 Mediates TNF-Stimulated Oxidant Activity in Skeletal Muscle" (2014). Physiology Faculty Publications. 64.
https://uknowledge.uky.edu/physiology_facpub/64