Heterogeneous distribution of glutamine synthetase during rat liver development.

Abstract

Two days before birth, immunohistochemical detection of glutamine synthetase already reveals a heterogeneous distribution pattern related to the vascular architecture of the liver. Only a small number of hepatocytes in the vicinity of the efferent venules show relatively high staining intensity. Before that age, only megakaryocytes show intense staining, while liver parenchyma is only faintly stained. The developmental profile of glutamine synthetase activity shows two periods of increasing enzyme activity: one in the perinatal period and one in the second and third postnatal week. Both periods are correlated with high levels of circulating corticosteroid hormones. Although the relative number of intensely stained hepatocytes increases during the first rise in enzyme activity, the second rise is correlated with a decreasing number of glutamine synthetase-positive hepatocytes which, however, show a considerable increase in staining intensity. Carbamoylphosphate synthetase shows a homogeneous distribution pattern in the perinatal period. Conditions that lead during development to a relatively high level of glutamine synthetase expression in the pericentral compartment apparently originate before the appearance of conditions that lead to a relatively high level of carbamoylphosphate synthetase gene expression in the periportal compartment. Our results indicate that downstream localization of glutamine synthetase in liver acinus is essential from the perinatal period onwards, whereas reciprocal distribution of glutamine synthetase and carbamoylphosphate synthetase gene expression (that is found in adult rat liver) is not.

Human Umbilical Cord Blood as a Source of Transplantable Hepatic Progenitor Cells

“…GS mRNA, as well as ALB mRNA, was detected in 9 of 10 samples from different donors, CK-18 mRNA was detected in 4 of 10 samples, and AFP mRNA was seen in 2 of 10 samples. GS is known to be expressed in mature hepatocytes [19,20], CK-18 is expressed in the hepatocyte lineage [21,22], and AFP is expressed in hepatic progenitor cells, including oval cells [23,24]. These previous reports support our findings that the cultured cells had the same characteristics as the hepatocyte lineage.…”

Deletion of the γ-Aminobutyric Acid Transporter 2 (GAT2 and SLC6A13) Gene in Mice Leads to Changes in Liver and Brain Taurine Contents

“…Double labeling with antibodies to glutamine synthetase (Fig. 7B), which is a marker for perivenous hepatocytes (58), showed that GAT2 was expressed at the highest levels in periportal hepatocytes. (The antibody used here to label glutamine synthetase also labeled endothelial cells.)…”

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

“…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]. Thus, GS serves as a marker for a specialized hepatocyte population [11,12] arising before birth [4] and characterized further by a distinct growth potential in vitro Correspondence address: R. Gebhardt, Physiologischchemisches Institut, Universit~.t Ttibingen, Hoppe-Seyler-Str. 4, D-7400 Tiibingen, FRG [13,14] and presumably by a separate cellular lineage during hepatocarcinogenesis [15].…”