| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||
,
* Centre for Microbial Diseases and Immunity Research,
Michael Smith Laboratories, and
Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
The human cationic host defense peptide LL-37 has a broad range of immunomodulatory, anti-infective functions. A synthetic innate defense regulator peptide, innate defense regulator 1 (IDR-1), based conceptually on LL-37, was recently shown to selectively modulate innate immunity to protect against a wide range of bacterial infections. Using advanced proteomic techniques, ELISA, and Western blotting procedures, GAPDH was identified as a direct binding partner for LL-37 in monocytes. Enzyme kinetics and mobility shift studies also indicated LL-37 and IDR-1 binding to GAPDH. The functional relevance of GAPDH in peptide-induced responses was demonstrated by using gene silencing of GAPDH with small interfering RNA (siRNA). Previous studies have established that the induction of chemokines and the anti-inflammatory cytokine IL-10 are critical immunomodulatory functions in the anti-infective properties of LL-37 and IDR-1, and these functions are modulated by the MAPK p38 pathway. Consistent with that, this study demonstrated the importance of the GAPDH interactions with these peptides since gene silencing of GAPDH resulted in impaired p38 MAPK signaling, downstream chemokine and cytokine transcriptional responses induced by LL-37 and IDR-1, and LL-37-induced cytokine production. Bioinformatic analysis, using InnateDB, of the major interacting partners of GAPDH indicated the likelihood that this protein can impact on innate immune pathways including p38 MAPK. Thus, this study has demonstrated a novel function for GAPDH as a mononuclear cell receptor for human cathelicidin LL-37 and immunomodulatory IDR-1 and conclusively demonstrated its relevance in the functioning of cationic host defense peptides.
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 We appreciate the financial support from the Foundation for the National Institutes of Health and Canadian Institutes for Health Research through the Grand Challenges in Global Health Initiative and Genome British Columbia and Genome Prairie for the Pathogenomics of Innate Immunity Research Program. R.E.W.H. and L.J.F. are recipients of Canada Research Chairs and L.J.F. is also a Michael Smith Foundation Scholar.
2 Current address: Manitoba Centre for Proteomics and Systems Biology, Department of Internal Medicine, University of Manitoba, MB, Canada.
3 Address correspondence and reprint requests to Dr. Robert E. W. Hancock, Centre for Microbial Diseases and Immunity Research, University of British Columbia, Vancouver, British Columbia, Canada. E-mail address: bob{at}cmdr.ubc.ca
4 Abbreviations used in this paper: FPRL-1, formyl peptide receptor-like 1; IDR-1, innate defense regulator 1;SILAC, stable isotope labeling of amino acids in cell culture; siRNA, small interfering RNA; MS, mass spectrometry; qRT-PCR, quantitative real-time PCR; WT, wild type; KD, knockdown; Ct, cycle threshold; MT, mock transfected; LTA, lipoteichoic acid.
5 The online version of this article contains supplemental material.
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
