Protein kinase C-delta is involved in the inflammatory effect of IL-6 in mouse adipose cells.
OBJECTIVE
The aim of the study was to address the role of protein kinase C-delta (PKCdelta) on phosphorylation of signal transducer and activator of transcription 3 (STAT3) and activation of inflammatory genes in response to IL-6 in adipose cells.


METHODS
Differentiated mouse 3T3-L1 adipocytes preincubated with the PKCdelta inhibitor rottlerin and mouse embryonic fibroblasts (MEFs) lacking PKCdelta were incubated with IL-6 and/or insulin. RNA was extracted and the gene expression was analysed by real-time PCR, while the proteins from total, nuclear and cytoplasmic lysates were analysed by immunoblotting.


RESULTS
Inhibition of PKCdelta by rottlerin significantly reduced both Ser-727 and Tyr-705 phosphorylation of STAT3. Consequently, nuclear translocation of STAT3 and the IL-6-induced gene transcription and protein release of the inflammatory molecule serum amyloid A 3 (SAA3) were reduced. Similarly, the IL-6-regulated gene transcription of Il-6 (also known as Il6) to Hp and the feedback inhibitor of IL-6, Socs3, were also attenuated by rottlerin. Furthermore, PKCdelta was found to translocate to the nucleus following IL-6 treatment and this was also reduced by rottlerin. In agreement with the effect of rottlerin, Pkcdelta (also known as Prkcd) ( -/- ) MEFs also displayed a markedly reduced ability of IL-6 to activate the transcription of Saa3, Hp, Socs3 and Il6 genes compared with wild-type MEFs. These results correlated with a reduced nuclear translocation and phosphorylation of STAT3.


CONCLUSIONS
These results show that PKCdelta plays a key role in the inflammatory effect of IL-6 in adipose cells and may be a suitable target for novel anti-inflammatory agents.
The Lundberg Laboratory for Diabetes Research, Center of Excellence for Cardiovascular and Metabolic Research, Department of Molecular and Clinical Medicine/Diabetes, The Sahlgrenska Academy at University of Gothenburg, Blå Stråket 5, SE-413 45, Gothenburg, Sweden.
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Wallerstedt
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Smith
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Andersson
D000098:Acetophenones / Q000494:pharmacology; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001578:Benzopyrans / Q000494:pharmacology; D015153:Blotting, Western; D002460:Cell Line; D002478:Cells, Cultured; D015870:Gene Expression / Q000187:drug effects / Q000235:genetics; D007249:Inflammation / Q000235:genetics / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism* / Q000494:pharmacology; D051379:Mice; D010766:Phosphorylation / Q000187:drug effects / Q000235:genetics; D051745:Protein Kinase C-delta / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism; D000685:Serum Amyloid A Protein / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D018709:Statistics, Nonparametric; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics
D000098:Acetophenones; D001578:Benzopyrans; D015850:Interleukin-6; D050796:STAT3 Transcription Factor; C076498:Saa3 protein, mouse; D000685:Serum Amyloid A Protein; C085746:rottlerin; D051745:Protein Kinase C-delta