Dissemin is shutting down on January 1st, 2025

Published in

Elsevier, Journal of Biological Chemistry, 32(289), p. 22401-22412, 2014

DOI: 10.1074/jbc.m114.589648

Links

Tools

Export citation

Search in Google Scholar

Defining a Role for Acid Sphingomyelinase in the p38/Interleukin-6 Pathway

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

Full text: Download

Green circle
Preprint: archiving allowed
Green circle
Postprint: archiving allowed
Green circle
Published version: archiving allowed
Data provided by SHERPA/RoMEO

Abstract

Acid sphingomyelinase (ASM) is one of the key enzymes involved in regulating the metabolism of the bioactive sphingolipid ceramide in the sphingolipid salvage pathway, yet defining signaling pathways by which ASM exerts its effects has proven difficult. Previous literature has implicated sphingolipids in the regulation of cytokines such as interleukin-6 (IL-6), but the specific sphingolipid pathways and mechanisms involved in inflammatory signaling need to be further elucidated. In this work we sought to define the role of ASM in IL-6 production as our previous work showed that a parallel pathway of ceramide metabolism, acid β-glucosidase 1 (GBA1), negatively regulates IL-6. First, silencing ASM with siRNA abrogated IL-6 production in response to the tumor promoter, 4β-phorbol 12-myristate 13-acetate (PMA), in MCF-7 cells, in distinction to GBA1 and acid ceramidase (ACD), suggesting specialization of the pathways. Moreover, treating cells with siRNA to ASM or with the indirect pharmacologic inhibitor desipramine resulted in significant inhibition of TNF-α- and PMA-induced IL-6 production in MDA-MB-231 and HeLa cells. Knockdown of ASM was found to significantly inhibit PMA-dependent IL-6 induction at the mRNA level, likely ruling out mechanisms of translation or secretion of IL-6. Further, ASM knockdown or desipramine blunted p38 MAPK activation in response to TNFα, revealing a key role for ASM in activating p38, a signaling pathway known to regulate IL-6 induction. Lastly, knockdown of ASM dramatically blunted invasion of HeLa and MDA-MB-231 cells through matrigel. Taken together, these results demonstrate that ASM plays a critical role in p38 signaling and IL-6 synthesis with implications for tumor pathobiology.