Acquisition of antigens characteristic of adult pericentral hepatocytes by differentiating fetal hepatoblasts in vitro.

Abstract

Abstract. Antigens specific to pericentral hepatocytes have been studied in adult mouse liver, during fetal development, and in cultured fetal hepatoblasts. Antibody reactive with glutamine synthetase stained all fetal liver cells but almost all cells lost this antigen after birth; only a single layer of pericentral cells retained it in adulthood. In contrast, monoclonal antibodies to major urinary protein (MUP) did not detect the antigen until •3 wk after birth, after which time the cells within 6-10 call diameters of the central veins were positive. Cultured fetal liver cells from embryos at 13 + 1 d of gestation were capable of differentiating in vitro to mimic events that would occur had the cells remained in the animal. About 10-20 % of the explanted cells grew into clusters of hepatocyte-like cells, all of which stained with albumin antibodies. MUP monoclonals were reactive with one-half of the differentiated fetal hepatocytes. Glutamine synthetase was present in all hepatocytes after several days in culture and gradually decreased and remained in only occasional cells, all of which also contained the MUP antigen.These findings suggest that a sequence of gene controis characterizes expression of specific genes in developing liver, and that differentiating fetal hepatoblasts are capable of undergoing similar patterns of gene activity in culture.T rIE adult liver is arranged in acini with the afferent blood supply from the portal vein and the portal artery entering branching vessels at the microscopic level deliver blood to capillary-sized vessels, termed sinusoids, which conduct blood between cords (or plates) of hepatocytes to empty into a central vein. Thus hepatocytes are divided into two zones or regions: periportal (close to the portal afferent circulation) or pericentral (close to the efferent central vein) (51). It is widely accepted that all hepatocytes in rodents and humans contain certain proteins (for example albumin), while other proteins are found at higher levels in cells of one or the other zone (4,8,23,24,32,33,42,55,58,59), perhaps related to the higher nutrient, hormone, and/or oxygen content of blood in periportal compared with the pericentral region. However recent work using immunohistochemical labeling shows a distinct pericentral location for a number of different detoxification enzymes whose regulation is not obviously related to nutrient or oxygen supply (2, 52, 62). These antigens are present either exclusively or predominantly in the 6-10 cell layers immediately surrounding the central vein in adult rodents. In addition, antibodies to glutamine synthetase show this enzyme to be present in rats in a single layer of pericentral cells (22). To supplement our studies on gene expression in mouse hepatocytes, which have emphasized the importance of cell surface contacts in maintaining hepatocyte specific transcription (12), and to begin to examine hepatocytes during fetal development, we prepared a series of mAbs against mouse liver tissue. Many of the first group ofmAbs we obtained rec...

Positional and developmental regulation of glutamine synthetase expression in mouse liver.

“…Differentiation of hepatocytes is characterized by the coordinated expression of many secreted proteins, such as those found in serum and enzymes active in gluconeogenesis, the urea cycle, or detoxification (16). A good many of these products, serum albumin being the classic example (2,21), appear to be produced equally by all hepatocytes in accord with the idea of there being a single cell lineage for all hepatocytes. However, it has also been recognized for many years that the concentration of some specialized hepatic proteins was not uniform throughout the liver acini (9,16).…”

“…In the past, this heterogeneity has been attributed largely to gradients of metabolites that exist across the hepatic acini (12, 15) which might be expected to generate gradients of protein concentrations. However, recent examinations have revealed sharp demarcations in the distribution of some specific proteins and mRNAs so that all-or-none positional effects on gene expression seem possible (1,2,9,21). This is perhaps most dramatically illustrated by the presence in adult mouse (2) and rat (10) liver of glutamine synthetase (GS) in a single-cell layer surrounding the central vein.…”

Heterogeneous expression of glutamine synthetase mRNA in rat liver parenchyma revealed by in situ hybridization and Northern blot analysis of RNA from periportal and perivenous hepatocytes

“…The unique restriction of this enzyme to small rings of hepatocytes encircling the terminal hepatic venules has now been convincingly demonstrated for the rat [2][3][4][5][6] as well as for other mammalian species [7,8] including man [9]. In addition, the localization of GS is distinct from that of other hepatic enzymes by its apparent inflexibility preventing an adaptive shift or an enlargement of the enzyme-positive zone under a variety Of physiological as well as experimental conditions [3,6,10].…”

Position-dependent activity of α-fetoprotein enhancer element III in the adult liver is due to negative regulation

“…7). For example, glutamine synthetase and ornithine aminotransferase are expressed exclusively in a narrow band of cells surrounding the central veins (8)(9)(10).…”