Effects of extracellular matrix on the expression of peroxisomes in primary rat hepatocyte cultures.
OBJECTIVE
Peroxisomes in wild-type cells vary between tissues and developmental stages. In the liver of some peroxisomal deficiency disorder patients, rare parenchymal cells express normal peroxisomes (mosaics); the mechanism is unknown. Our aim was to find factors regulating peroxisome expression.


METHODS
Liver-specific as well as peroxisome characteristics were studied in three types of primary rat hepatocyte cultures.


RESULTS
Total glutathione S-transferase activity and albumin secretion both increased in the collagen I sandwich and immobilization gel cultures. In contrast, in monolayers cultured on plastic, total glutathione S-transferase activity decreased and albumin secretion was only 30-40% compared to the collagen cultures. Glycogen rosettes typical of liver parenchymal cells were always abundant. Laminin and collagen IV-producing stellate cells were numerous in the monolayer but almost absent in the sandwich cultures. In 6-day-monolayer cultures, the number of liver-specific peroxisomes had decreased while atypical small or elongated peroxisomes appeared. Immunolabeling density for catalase and three beta-oxidation enzymes was decreased compared to adult rat liver; catalase specific activity in homogenates had dropped to 15% and 4% in the sandwich and monolayer cultures, respectively. In 17-day-sandwich cultures, some peroxisomes showed a very weak catalase reaction; total activity was 5%. Supplementation of the collagen type I cultures with several extracellular matrix factors could not prevent peroxisome dedifferentiation.


CONCLUSIONS
The presence of these extracellular matrix components is not sufficient for normal peroxisome expression. It is suggested that hepatocyte-specific and peroxisomal features are regulated differently. The sandwich preserves hepatocyte differentiation better than the monolayer.
Depreter
M
M
University of Ghent, Department of Anatomy, Embryology and Histology, Belgium. marianne.depreter@rug.ac.be
Tytgat
T
T
Beken
S
S
Espeel
M
M
De Smet
K
K
Rogiers
V
V
Roels
F
F
D000818:Animals; D002374:Catalase / Q000378:metabolism; D002478:Cells, Cultured; D003094:Collagen; D003584:Cytological Techniques; D005109:Extracellular Matrix / Q000502:physiology*; D005782:Gels; D005982:Glutathione Transferase / Q000378:metabolism; D007150:Immunohistochemistry; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008297:Male; D020675:Peroxisomes / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D012709:Serum Albumin / Q000378:metabolism; D014018:Tissue Distribution
D005782:Gels; D012709:Serum Albumin; D003094:Collagen; D002374:Catalase; D005982:Glutathione Transferase