Dataset Information

Leishmania donovani infection enhances lateral mobility of macrophage membrane protein which is reversed by liposomal cholesterol.

ABSTRACT:

Background

The protozoan parasite Leishmania donovani (LD) reduces cellular cholesterol of the host possibly for its own benefit. Cholesterol is mostly present in the specialized compartment of the plasma membrane. The relation between mobility of membrane proteins and cholesterol depletion from membrane continues to be an important issue. The notion that leishmania infection alters the mobility of membrane proteins stems from our previous study where we showed that the distance between subunits of IFN? receptor (R1 and R2) on the cell surface of LD infected cell is increased, but is restored to normal by liposomal cholesterol treatment.

Methodology/principal findings

We determined the lateral mobility of a membrane protein in normal, LD infected and liposome treated LD infected cells using GFP-tagged PLC?1 as a probe. The mobility of PLC?1 was computationally analyzed from the time lapse experiment using boundary distance plot and radial profile movement. Our results showed that the lateral mobility of the membrane protein, which is increased in infection, is restored to normal upon liposomal cholesterol treatment. The results of FRAP experiment lent further credence to the above notion. The membrane proteins are intimately linked with cellular actin and alteration of cellular actin may influence lateral mobility. We found that F-actin is decreased in infection but is restored to normal upon liposomal cholesterol treatment as evident from phalloidin staining and also from biochemical analysis by immunoblotting.

Conclusions/significances

To our knowledge this is the first direct demonstration that LD parasites during their intracellular life cycle increases lateral mobility of membrane proteins and decreases F-actin level in infected macrophages. Such defects may contribute to ineffective intracellular signaling and other cellular functions.

SUBMITTER: Ghosh M

PROVIDER: S-EPMC4256160 | biostudies-literature | 2014 Dec

REPOSITORIES: biostudies-literature

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Publications

Leishmania donovani infection enhances lateral mobility of macrophage membrane protein which is reversed by liposomal cholesterol.

Ghosh Moumita M Roy Koushik K Das Mukherjee Dipanwita D Chakrabarti Gopal G Roy Choudhury Kingshuk K Roy Syamal S

PLoS neglected tropical diseases 20141204 12

<h4>Background</h4>The protozoan parasite Leishmania donovani (LD) reduces cellular cholesterol of the host possibly for its own benefit. Cholesterol is mostly present in the specialized compartment of the plasma membrane. The relation between mobility of membrane proteins and cholesterol depletion from membrane continues to be an important issue. The notion that leishmania infection alters the mobility of membrane proteins stems from our previous study where we showed that the distance between ...[more]

PMID: 25474261

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Project description:Despite the presence of significant levels of systemic Interferon gamma (IFNγ), the host protective cytokine, Kala-azar patients display high parasite load with downregulated IFNγ signaling in Leishmania donovani (LD) infected macrophages (LD-MØs); the cause of such aberrant phenomenon is unknown. Here we reveal for the first time the mechanistic basis of impaired IFNγ signaling in parasitized murine macrophages. Our study clearly shows that in LD-MØs IFNγ receptor (IFNγR) expression and their ligand-affinity remained unaltered. The intracellular parasites did not pose any generalized defect in LD-MØs as IL-10 mediated signal transducer and activator of transcription 3 (STAT3) phosphorylation remained unaltered with respect to normal. Previously, we showed that LD-MØs are more fluid than normal MØs due to quenching of membrane cholesterol. The decreased rigidity in LD-MØs was not due to parasite derived lipophosphoglycan (LPG) because purified LPG failed to alter fluidity in normal MØs. IFNγR subunit 1 (IFNγR1) and subunit 2 (IFNγR2) colocalize in raft upon IFNγ stimulation of normal MØs, but this was absent in LD-MØs. Oddly enough, such association of IFNγR1 and IFNγR2 could be restored upon liposomal delivery of cholesterol as evident from the fluorescence resonance energy transfer (FRET) experiment and co-immunoprecipitation studies. Furthermore, liposomal cholesterol treatment together with IFNγ allowed reassociation of signaling assembly (phospho-JAK1, JAK2 and STAT1) in LD-MØs, appropriate signaling, and subsequent parasite killing. This effect was cholesterol specific because cholesterol analogue 4-cholestene-3-one failed to restore the response. The presence of cholesterol binding motifs [(L/V)-X(1-5)-Y-X(1-5)-(R/K)] in the transmembrane domain of IFNγR1 was also noted. The interaction of peptides representing this motif of IFNγR1 was studied with cholesterol-liposome and analogue-liposome with difference of two orders of magnitude in respective affinity (K(D): 4.27×10(-9) M versus 2.69×10(-7) M). These observations reinforce the importance of cholesterol in the regulation of function of IFNγR1 proteins. This study clearly demonstrates that during its intracellular life-cycle LD perturbs IFNγR1 and IFNγR2 assembly and subsequent ligand driven signaling by quenching MØ membrane cholesterol.

Project description:Infection with antimony resistant (SbR) but not with sentitive (SbS) Leishmania donovani (LD) gives rise to aggressive pathology in mammalian hosts, the cause of which is far from clear. Some intracellular pathogens exploit autophagy for their own benefit. Here we show that induction of autophagy in normal macrophages (MF) by pharmacological mediators prior to infection with SbRLD (SbRLD-MF) enhanced their growth as compared to untreated MF, unlike SbSLD-MF. Autophagy was evident in SbRLD-MF from electron microscopical studies showing double membrane-bound compartment around amastigote. In SbRLD-MF there is induction of beclin 1, which forms the platform to recruit other interacting molecules to initiate autophagy. Knocking down the beclin 1 transcription factor Nrf2 and subsequent infection with SbRLD showed significantly lower organ parasites as compared to wild type BALB/c mice. Cessation of autophagy in SbRLD-MF at the later stage of infection is coupled with induction of miR-30a, whose binding to 3'UTR of beclin 1 leads to its post-transcriptional attenuation followed by rise in intracellular Ca++ and apoptosis. SbRLD mediated translocation of AP-1 transcription factor to the nucleus induce pri-miR-30a over-expression. Rise in Ca++ causes caspase 8 activtion leading to the cleavage of beclin 1 and initiation of apoptosis in SbRLD-MF. Apoptosis may favor parasite egress for cell to cell transmission. We also found that beclin 1 expression is present in splenocytes of kala-azar patients harbouring SbRLD but not SbSLD. Our results suggest that SbRLD has evolved a unique mechanism for its own benefit which explains, in part, the cause of aggressive pathology. Peritoneal exudate macrophages were isolated from mouse, grown in 60mm plates and infected with Leishmania donovani and total RNA was isolated from cells at 12, 18 and 24 hrs post infection. Leishmania infected macrophage miRNA expression signature was generated. Cells grown on 60mm plates and infected with Leishmania. The main objective of the microarray analysis of mmu-miRNA in antimony resistant and antimony sensitive Leishmania donovani infected macrophages are as follows: 1. To study how the expression of miRNA varies in either antimony resistant or antimony sensitive Leishmania infected macrophages as compared to the normal macrophages as a function of time. LPS was used as control. 2. To study the expression of those miRNAs which are differentially expressed in antimony resistant and antimony sensitive Leishmania infected macrophages at each time point post infection. 3. To identify those miRNAs which are responsible for degradation of autophagy initiating protein beclin 1 mRNA

Dataset Information

Leishmania donovani infection enhances lateral mobility of macrophage membrane protein which is reversed by liposomal cholesterol.

Background

Methodology/principal findings

Conclusions/significances

Publications

Leishmania donovani infection enhances lateral mobility of macrophage membrane protein which is reversed by liposomal cholesterol.

Similar Datasets

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