Regulation of CC Ligand 5/RANTES by Acid Sphingomyelinase and Acid Ceramidase

Abstract

In the present study using a chemokine/cytokine screen, we identified the chemokine CCL5 (formerly known as RANTES) as a candidate-specific downstream target for aSMase. Regulation of CCL5 by aSMase was subsequently validated using both loss-offunction and gain-of-function models indicating that aSMase is both necessary and sufficient for CCL5 production. Interestingly, cells deficient in acid ceramidase (aCDase) also exhibited defects in CCL5 induction, whereas cells deficient in sphingosine kinase-1 and -2 exhibited higher levels of CCL5, suggesting that sphingosine and not sphingosine 1-phosphate (S1P) is responsible for the positive signal to CCL5. Consistent with this, co-expression of aSMase and aCDase was sufficient to strongly induce CCL5. Taken together, these data identify a novel role for aSMase (particularly S-SMase) in chemokine elaboration by pro-inflammatory cytokines and highlight a novel and shared function for aSMase and aCDase.

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

“…Previous work from our laboratory has demonstrated a role for ASM in the production of the chemokine, CCL5/RANTES (17). Interestingly, this is probably a distinct pathway of regulation from that by which ASM regulates IL-6.…”

“…The primer set, which would amplify both species, was only used for semiquantitative PCR, whereas the others were used for qRT-PCR. ASM, CCL5/RANTES, and ␤-actin primer sequences were described previously (12,17).…”

“…Moreover, the availability of fibroblasts from patients with NPD, which have significantly decreased ASM activity (17), allows evaluation of the role of ASM in a genetic model. Here we found that NPD fibroblasts have profoundly defective IL-6 SCHEME 1.…”

“…in our laboratory (8,17) and were further validated either by Western blot or real-time PCR (Fig. 1, E and F).…”

“…Previous work has demonstrated a role for ASM in the regulation of CCL5/RANTES in response to the cytokines, TNF␣ and IL-1␤ (17). In order to assess the possibility that PMA is also inducing RANTES through a novel mechanism, MCF-7 cells were treated with PMA and IL-6, and CCL5 mRNA was measured.…”