Expression of microfibrillar proteins by bovine bladder urothelium.
OBJECTIVE
To determine the occurrence and potential function of proteins composing elastic microfibrils in the developing bovine bladder.


METHODS
Monospecific antibodies, generated against two well-characterized microfibrillar proteins, microfibril-associated glycoprotein (MAGP) and fibrillin-1 (FBN1), were used in immunohistochemical analysis of full-thickness frozen sections of fetal bovine bladder. The localization of these two antibodies was compared with that of anti-type IV collagen antibody. Adjacent serial sections were stained for routine light microscopy. Cultured urothelial cells were fixed in 3.7% formaldehyde and permeabilized with 0.5% Triton X-100 before immunoanalysis. Control reactions used either preimmune serum or a monoclonal antibody to a nonmatrix protein. Poly(A+) ribonucleic acid was isolated from cultured urothelial cells and subjected to Northern analysis using specific complementary deoxyribonucleic acid probes for MAGP and FBN1.


RESULTS
Both MAGP and FBN1 are expressed by the urothelium and are found in association with the underlying basement membrane, as visualized by their co-localization with type IV collagen. Furthermore, urothelial cells in culture continue to express both microfibrillar proteins.


CONCLUSIONS
The developing bovine urothelium expresses major microfibrillar protein components. The role of these microfibrils in the urothelium remains to be determined, but they may have an important anchoring function.
Rosenbloom
J
J
Department of Anatomy and Histology, School of Dental Medicine, University of Pennsylvania, Philadelphia 19104, USA.
Abrams
W R
WR
Rosenbloom
J
J
Kucich
U
U
Decker
S
S
Mecham
R
R
Macarak
E
E
Howard
P
P
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D003285:Contractile Proteins / Q000096:biosynthesis*; D004547:Elastic Tissue / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis*; D000071837:Fibrillins; D007150:Immunohistochemistry; D008840:Microfilament Proteins / Q000096:biosynthesis*; D000072260:RNA Splicing Factors; D001743:Urinary Bladder / Q000378:metabolism*; D019459:Urothelium / Q000378:metabolism
D003285:Contractile Proteins; D016326:Extracellular Matrix Proteins; D000071837:Fibrillins; D008840:Microfilament Proteins; D000072260:RNA Splicing Factors; C016598:microfibrillar protein