Faculty Collaboration Database

Unmethylated CpG motifs in the L. donovani DNA regulate TLR9-dependent delay of programmed cell death in macrophages. J Leukoc Biol 2015 Feb;97(2):363-78

Date

12/05/2014

Pubmed ID

25473100

DOI

10.1189/jlb.4A0713-378RR

Scopus ID

2-s2.0-84925372254 (requires institutional sign-in at Scopus site)   15 Citations

Abstract

Regulation of macrophage PCD plays an important role in pathogenesis of leishmaniasis. However, the precise involvement of any parasite molecule in this process remains uncertain. In the current study, in silico wide analysis demonstrated that genes in the Leishmania donovani genome are highly enriched for CpG motifs, with sequence frequency of 8.7%. Here, we show that unmethylated species-specific CpG motifs in LdDNA significantly (P = 0.01) delay macrophage PCD by endosomal interaction with TLR9 via the adaptor protein MyD88. Importantly, LdDNA triggered high levels of luciferase activity (P = 0.001) under NF-κB-dependent transcription in HEK-TLR9 cells. Furthermore, the activation of caspases in macrophages was inhibited (P = 0.001) in the presence of LdDNA. Notably, the delay of PCD was mediated by modulation of the antiapoptotic proteins, Mcl-1 and Bfl-1, and impairment of loss of Δψm in macrophages through the neutralization of oxidative and nitrosative stress. The inhibition of caspase activation and up-regulation of Mcl-1 by LdDNA were TLR9 dependent. Analysis of the targets of LdDNA identified an early activation of the TLR9-dependent PI3K/Akt and SFK pathways, which were required for the observation of the antiapoptotic effects in macrophages. Moreover, we demonstrate that LdDNA modulates the TLR9-IκB-α pathway by promoting the tyrosine phosphorylation of TLR9 and the TLR9-mediated recruitment of Syk kinase. The results have identified a novel, TLR9-dependent antiapoptotic function of LdDNA, which will provide new opportunities for discovering and evaluating molecular targets for drug and vaccine designing against VL.

Author List

Das S, Ghosh AK, Singh S, Saha B, Ganguly A, Das P

Author

Ayan K. Ghosh PhD Research Scientist I in the Pediatrics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Apoptosis
Caspases
CpG Islands
DNA Methylation
DNA, Protozoan
Enzyme Activation
Female
HEK293 Cells
Humans
Leishmania donovani
Macrophages
Male
Myeloid Cell Leukemia Sequence 1 Protein
Myeloid Differentiation Factor 88
Phosphorylation
Toll-Like Receptor 9
Up-Regulation