Expression of the mouse serum albumin gene introduced into differentiated and dedifferentiated rat hepatoma cells.

Abstract

A 23-kilobase-pair segment of DNA containing the entire mouse serum albumin gene as well as 2.2 kilobase pairs of 5' and 4.3 kilobase pairs of 3' flanking sequences has been introduced into pSV2dhfr, a plasmid in which expression of the mouse dihydrofolate reductase cDNA is under the control of simian virus 40 sequences. This vector, pSV2dhfr-alb, was used to transfect differentiated and variant dedifferentiated rat hepatoma cells. Nine independent clones of transfected differentiated cells secrete considerable amounts of mouse albumin, while the expression of the normal rat albumin is the same as in nontransfected cells. In contrast, only small amounts of mouse and rat albumin are produced by transfected dedifferentiated cells. The amounts of albumin mRNA present in the cells are consistent with the amounts of albumin produced. These results show that a transfected gene can be regulated in a fashion consistent with the overall differentiation profile of the cell.

A mouse minialbumin gene is specifically expressed in differentiated hepatoma cells but not in transgenic mice

“…Introduction into cultured cells of cloned genes encoding for tissue-specific functions results in preferential expression in the appropriate cell types [5,8,20,351. The mouse albumin gene is specifically expressed in stably transfected differentiated rat hepatoma clones, while in transfected dedifferentiated variants the level of expression is significantly lower [8].…”

“…Introduction into cultured cells of cloned genes encoding for tissue-specific functions results in preferential expression in the appropriate cell types [5,8,20,351. The mouse albumin gene is specifically expressed in stably transfected differentiated rat hepatoma clones, while in transfected dedifferentiated variants the level of expression is significantly lower [8]. Analysis of gene-specific expression performed in short-term transfection experiments has shown that DNA sequences a few ten or hundred nucleotides in length are instrumental in enhancement of expression in differentiated cells of specific lineages [9, 11, 18, 421. In the case of the rat albumin gene, the immediate 5'-flanking region of the gene fused to the chloramphenicol acetyltrans$erase (CAT) gene specifically elicits high CAT activity in transfected hepatoma cells [28].…”

“…The present experiments had already been completed when Pinkert et al [30] reported expression in transgenic mice of a human growth hormone reporter gene fused to various lengths of the 5'-flanking region of the mouse albumin gene. High-level expression of the human growth hormone reporter gene in adult liver required the presence of a DNA element located 8.5-10.4 kb upstream of the albumin promoter, and that was absent in the transfection experiments mentioned above [8,281. However, conclusions based on chimeric genes, especially with the growth hormone gene, are open to debate, because DNA sequence elements within reporter genes may act in a combinatorial fashion with the regulatory DNA elements under study, and unexpected expression can result [37].…”

Immunity to melanoma in mice immunized with transfected allogeneic mouse fibroblasts expressing melanoma-associated antigens

“…In addition to those that transform nonmalignant cells [23,31], the successful transfer of genes that specify specific proteins [7,10], and alter the hormonal responsiveness of neoplastic cells [19,28], has been accomplished. The transfer and expression of genes specifying membrane-associated proteins was achieved as well, indicating that complex intracellular processing mechanisms could be applied by the recipient cells to express the products of exogenous DNAs [9,18].…”

Binding of a liver-specific factor to the human albumin gene promoter and enhancer.

“…However, additional sequences may be required for transcriptional control during development, since an enhancer located at -10 kilobases (kb) from the cap site is essential for high-level expression of the albumin gene in transgenic mice (40). Comparison of the rodent albumin 5'-flanking sequences with the human counterpart demonstrates more than 90%o sequence conservation up to position -250, indicating that these promoter sequences are recognized by evolutionarily conserved proteins (7,13). The characterized DNA-binding proteins interacting with these cis-acting sequences in the rat albumin promoter (2, 7) and in the mouse promoter (28, 29) include the liver-specific LF-Bl/HNF1 (1Sa) and C/EBP (26), and the ubiquitous CTF/NF1 (39, 45) and NFY (43).…”