Presence of a 300-kDa intermediate-filament-associated protein (IFAP-300kDa) in bovine chromaffin cells.
Intermediate filaments (IFs) are cell-type-specific filaments that constitute a major part of the cellular cytoskeleton. Neurofilaments (NFs) are representative of a class of IFs which are excellent markers for neurons. NFs are also present in some cells of neural crest origin. A number of proteins have now been identified as being associated with IFs. Previously, a 300-kDa intermediate-filament-associated protein (IFAP-300kDa) was identified in baby hamster kidney cells (BHK-21). This IFAP is developmentally regulated and is not found in the adult CNS. To learn more about the expression of IFAP-300kDa, this study investigated the expression of IFAP-300kDa in neural-crest-derived chromaffin cells, both in situ and in vitro. Immunofluorescence localization of IFAP-300kDa in cryosections of bovine adrenal gland demonstrated IFAP-300kDa immunoreactivity in the dopamine-beta-hydroxylase-positive chromaffin cells of the adrenal medulla. When rounded chromaffin cells in culture were examined, double-label immunofluorescence microscopy revealed an IFAP-300kDa/NF-L-positive juxtanuclear aggregate. The plasma membrane was also IFAP-300kDa positive, but NF-L immunoreactivity was lacking. In cells which have spread under the influence of NGF, slender IFAP-300kDa-positive immunofluorescent strands were frequently seen radiating from a juxtanuclear area of immunoreactivity. Double-labeling revealed these filaments and juxtanuclear area to also be positive for NF-L immunoreactivity. The presence of IFAP-300kDa in situ and in vitro was further confirmed by immunoblot analysis. This study is the first demonstration of an IFAP in neuron-like cells located outside the central nervous system. In addition, these data indicate that the developmentally regulated IFAP-300kDa may persist in some cells of neural crest origin.
Department of Anatomy, Medical Colleges, University of Illinois at Chicago, 60612, USA.
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D000311:Adrenal Glands / Q000737:chemistry / Q000166:cytology; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured / Q000737:chemistry / Q000648:ultrastructure; D019439:Chromaffin Cells / Q000737:chemistry* / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D015151:Immunoblotting; D007150:Immunohistochemistry; D007381:Intermediate Filament Proteins / Q000032:analysis*; D016253:Microscopy, Immunoelectron
D007381:Intermediate Filament Proteins