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Role of durg sensitive and resistant form of Leishmania donovani in controlling exosomal cargo release by host cell

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Title Role of durg sensitive and resistant form of Leishmania donovani in controlling exosomal cargo release by host cell
 
Creator Ganguly, Satarupa
 
Subject Molecular & Human Genetics
 
Description Post-transcriptional regulation of different mRNAs is one of the ways to control particular
gene expression and this type of regulation is mediated by a group of small RNAs known
as MicroRNAs (miRNA). These miRNAs are 20-22 nucleotide long and they can bind to
the 3’ UTR of target mRNA to initiate the translational repression or mRNA degradation.
They are found to be involve in the regulation of almost all biological phenomenon & their
alteration of expression is associated with various disease condition. miRNAs not only
regulate the expression of mRNAs of host cell but also can regulate expression of target
mRNAs in neighboring cell when it gets transferred by exosome. Exosomes are small
membrane bound vesicle of 30-100nm size and they are originated from Multivesicular
Bodies (MVB). But exosomes not only known to carry miRNAs but also carries different
proteins & lipids.
However, different pathological conditions can lead to alteration of exosomal cargoes and
their effect on neighboring cells. EVs play diverse role during a disease condition. It either
provides host protective molecules to neighboring cells or provide disease spreading
molecules or some virulence factors. Pathogens can regulate miRNA machinery as well as
EV secretion & cargo contents in order to survive within host cell. Leishmania donovani
(Ld) is an intracellular parasite that resides in macrophage and regulate its innate immune
system for their own survival. Ld affects endosome maturation thereby hampered miRNP
recycling which resulted in altered cytokine production. Also, it regulates cholesterol
metabolism by targeting miR-122 in liver cells and increases miRNA stability by targeting
mitochondrial dynamics in order to regulate the inflammatory response of macrophages.
Emergence of parasite resistance against anti-leishmanial drugs are adding new hurdles in
VL in nowadays. This made us interested in studying the effect of drug sensitive & resistant
parasite in regulating miRNA mediated immune response in host macrophage and also in
neighboring cells by regulating host cell exosomal machinery.
We have shown that both the strains reciprocally regulate PP2A and HuR expression. PP2A
dephosphorylates Ago2 to increase its association with miRNAs. This increased miRNAAgo2
association maintains the anti-inflammatory environment that favors parasite
survival within host cells. Several RNA binding proteins are known to regulate miRNA
mediated gene regulation. Such RNA binding protein is HuR which is a miRNA
derepressor protein responsible for miRNA-Ago2 uncoupling to favor the proinflammatory
environment that promote parasite killing.
In this study, we find that HuR overexpression decreases parasite load for the LdS strain in
in vivo. But cannot reduce parasite load for LdR strain. However, simultaneous inhibition
of PP2A by Okadaic acid treatment shows clearance of LdR parasites in in vivo mice model.
Upregulation of PP2A hampered miRNP recycling which might regulate the exosomal
release of miRNAs. Hence, we check the exosomal contents of macrophages after infection
with both strains and find increased level of miR-146a in exosome but interestingly miR-
155 is not detected. The neighboring macrophages showed M2 phenotype after exosome
treatment for LdS strain derived exosomes and it reduces LdS internalization. But
macrophages treated with LdR infected cell derive exosomes does not showed M2
phenotype but suppress both pro and anti-inflammatory cytokine production. However,
exosome treatment reduces LdR parasites internalization in naïve macrophages more
vigorously than their sensitive counterpart. We also found that exosomal transfer of miR-
146a not only regulate immune response of naïve macrophages but also show effect on
hepatic cells by downregulating miR-122 which involves in inflammatory response.
Our findings show a novel protective role of exosome in preventing Ld infection caused by
both drug sensitive & resistant strains, by means of increased exosomal export of miR-146a
from infected cell to uninfected macrophages and hepatocyte. Also, in this study we find a
new therapeutic role of HuR & okadaic acid in preventing the infection caused by the
aggressive drug resistant strain of Ld.
 
Date 2022
 
Type Thesis
NonPeerReviewed
 
Format application/pdf
 
Identifier http://www.eprints.iicb.res.in/2853/1/1646206560867_Thesis_for_Evaluation_Satarupa_Ganguly.pdf
Ganguly, Satarupa (2022) Role of durg sensitive and resistant form of Leishmania donovani in controlling exosomal cargo release by host cell. PhD thesis, UNIVERSITY OF CALCUTTA.
 
Relation http://www.eprints.iicb.res.in/2853/