LPS depletes PHLPP levels in macrophages through the inhibition of SP1 dependent transcriptional regulation.
We have previously reported that bacterial endotoxin LPS attenuates expression of PHLPP, a ser/thr phosphatase, at both transcript and protein levels in different immune cells, however the underlying molecular mechanism is unknown and is of significant interest. Here, in line with the decreased transcript levels upon LPS treatment, we observed that LPS caused significant reduction in PHLPP promoter activity. We observed that SP1, a transcription factor frequently associated with inflammation, was recruited to the PHLPP promoter region. Ectopic expression of SP1 enhanced both transcript and protein levels of PHLPP while knockdown of SP1 or pharmacological inhibition of SP1 DNA binding by mithramycin reduced PHLPP expression. Moreover, over-expression of SP1 co-activators CBP/p300 augmented SP1 driven PHLPP promoter activity. Of note, LPS treatment depleted SP1 and CBP protein levels due to which recruitment of SP1 to PHLPP promoter was reduced. Further, we found that re-introduction of SP1 restored promoter activity and transcript levels of PHLPP in LPS stimulated cells. Collectively, our data revealed the molecular mechanism underlying the regulation of PHLPP expression during LPS induced macrophage inflammatory response.
Department of Biology, Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Hyderabad, Telangana, India.
Neeraja P
NP
Alamuru-Yellapragada
Department of Biology, Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Hyderabad, Telangana, India.
Sanghamitra
S
Vundyala
Department of Biology, Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Hyderabad, Telangana, India.
Soma
S
Behera
Department of Biology, Dr. Reddy's Institute of Life Sciences, University of Hyderabad Campus, Hyderabad, Telangana, India. Electronic address: kishorep@drils.org.
Kishore V L
KV
Parsa
D000818:Animals; D002460:Cell Line; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D057809:HEK293 Cells; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D051379:Mice; D009000:Monocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000276:immunology; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000276:immunology; D008926:Plicamycin / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics* / Q000276:immunology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D016329:Sp1 Transcription Factor / Q000235:genetics* / Q000276:immunology; D014158:Transcription, Genetic; D050880:p300-CBP Transcription Factors / Q000235:genetics / Q000276:immunology
D008070:Lipopolysaccharides; D009687:Nuclear Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016329:Sp1 Transcription Factor; C108209:SP1 protein, human; D008156:Luciferases; D050880:p300-CBP Transcription Factors; C400601:PHLPP1 protein, human; D010749:Phosphoprotein Phosphatases; D008926:Plicamycin
Inflammation; LPS; Macrophages; PHLPP; SP1