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2015 ; 112
(48
): E6654-62
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Post-conversion sialylation of prions in lymphoid tissues
#MMPMID26627256
Srivastava S
; Makarava N
; Katorcha E
; Savtchenko R
; Brossmer R
; Baskakov IV
Proc Natl Acad Sci U S A
2015[Dec]; 112
(48
): E6654-62
PMID26627256
show ga
Sialylated glycans on the surface of mammalian cells act as part of a
"self-associated molecular pattern," helping the immune system to recognize
"self" from "altered self" or "nonself." To escape the host immune system, some
bacterial pathogens have evolved biosynthetic pathways for host-like sialic
acids, whereas others recruited host sialic acids for decorating their surfaces.
Prions lack nucleic acids and are not conventional pathogens. Nevertheless,
prions might use a similar strategy for invading and colonizing the
lymphoreticular system. Here we show that the sialylation status of the
infectious, disease-associated state of the prion protein (PrP(Sc)) changes with
colonization of secondary lymphoid organs (SLOs). As a result, spleen-derived
PrP(Sc) is more sialylated than brain-derived PrP(Sc). Enhanced sialylation of
PrP(Sc) is recapitulated in vitro by incubating brain-derived PrP(Sc) with
primary splenocytes or cultured macrophage RAW 264.7 cells. General inhibitors of
sialyltranserases (STs), the enzymes that transfer sialic acid residues onto
terminal positions of glycans, suppressed extrasialylation of PrP(Sc). A
fluorescently labeled precursor of sialic acid revealed ST activity associated
with RAW macrophages. This study illustrates that, upon colonization of SLOs, the
sialylation status of prions changes by host STs. We propose that this mechanism
is responsible for camouflaging prions in SLOs and has broad implications.
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