Publication: Products of unusual microtubule dynamics in monocyte-derived giant cells. An immunohistochemical study
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Date
1994
Authors
Gadde, P.S. ; Moscovic, E.A.
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Publisher
Murcia : F. Hernández
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DOI
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info:eu-repo/semantics/article
Description
Abstract
We have studied asteroid bodies (ABs) of
multinucleated giant cells (MGCs) in a series of sarcoid
and foreign body granulomas with a standard
streptavidin-biotin peroxidase technique, using
commercial antibodies against collagen, vimentin and
tubulin on routinely processed tissue as well as, in one
case, on fresh frozen sections (FS). Our findings clearly
indicate that ABs are products of the microtubule (MT)
system and lack collagen. The tubulin in them stains in
fresh FS but is «masked» in formalin-fixed tissue. It can
be fully «unmasked» by dephosphorylation and partially
by trypsinization. Compared to single microtubule
organizing centers (MTOCs) in mononuclear cells
serving as interna1 controls, ABs are obvious replicas of
centrosome-nucleated MT assemblies from which they
differ principally by the disproportionate size of their
components and by the invariable vacuolation of the
surrounding cytoplasm. Relying on bits of relevant
information gleaned from the literature, our observations
support the following preliminary conclusions: 1) spokes
are massive bundles of MTs nch in tyrosinated a-tubulin
coassembled in phosphorylated linkages with yet
unidentified microtubule associated proteins (MAPs) and probably microfilament proteins; cores are masses
of pericentriolar material including amorphous tubulins,
MAPs, phosphoproteins and phospholipids; 2) their size,
at least in some ABs, appears to indicate the presence of
overlapping centrosome-nucleated MTOCs which in
monocyte-derived MGCs are known to be multiple; 3)
the cytoplasmic vacuolations around them reflect a
collapse and retraction of intermediate filaments (IFs),
indicating substantial ongoing MT depolymerization
with disruption of MT-IF interactions; 4) ABs are
products of unusual MTOC dynamics characterized by
simultaneous MT assembly and depolymerization; such
a phenomenon, temed «microtubule catastrophec, has
been recognized in vitro with centrosome-nucleated MT assemblies under conditions of low tubulin
concentrations.
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