Abstracts (complete list) - Wissenschaft Online

Thorsten Stroh, Arvind Batra, Rainer Glauben, Inka Fedke, Stephen Girardin, Martin
Zeitz, Britta Siegmund
Expression of NOD2 but not NOD1 is modulated by proinflammatory
cytokines in murine preadipocytes
Preadipocytes are linked to the innate immune system indicated by their expression of
functional Toll-like receptors (TLR) and ability to phagocytosis. Recent studies of our
group revealed the expression of members of the nucleotide-binding site and leucinerich
repeat (NBS-LRR) proteins. These proteins belong to the family of intracellular
pattern recognition receptors which act as sensors for motifs found in the
peptidoglycans (PG) from bacteria. NOD1 binds to Lactyl-Tetra-DAP a peptidoglycan
motif mainly found in PG from Gram-negative bacteria, NOD2 detects muramyl
dipeptide (MDP) a motif contained in PG derived from Gram-positive bacteria.
This study aimed to investigate the expression of NOD1 and NOD2 and their
functionality in murine preadipocytes. Changes in expression were analysed after ligandspecific
stimulation and stimulation with pro-inflammatory cytokines using quantitative
real-time RT-PCR. Functionality of these receptors was tested by ligand-specific
stimulation, and the subsequent response was evaluated by IL-6 production and
activation of the NF-κB pathway. Specificity of stimulation was confirmed by RNA
interference (RNAi) strategies. NOD1 mRNA was detectable in all samples. The
expression was not altered after ligand–specific stimulation or stimulation with the
proinflammatory cytokines IL-1β and TNFα. In contrast, NOD2 was slightly increased by
NOD1-specific stimulation but could significantly be upregulated by stimulation with IL-
1β. The strongest upregulation was observed after stimulation with LPS but different
from stimulation with IL-1β or TNFα, LPS-induced upregulation was only present after
4h of stimulation. Specific stimulation of NOD1 by LT-DAP resulted in a strong activation
of the NF-κB pathway and a significant IL-6 production could be observed.
Our data provide evidence that functional NBS-LRR proteins are expressed in
preadipocytes and that expression of NOD2 can be modulated by pro-inflammatory
cytokines. Thus underlining the position of preadipocytes in the innate immune system.