Nucleus-dependent regulation of tyrosine aminotransferase degradation in hepatoma tissue culture cells.

Fan, W W; Ivarie, Robert; Levinson, Barbara

doi:10.1016/s0021-9258(17)41042-8

Cited by 19 publications

(4 citation statements)

References 25 publications

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“…Furthermore, AIB uptake by cytoplasts prepared from cells previously incubated with dexamethasone does not increase to its uninhibited level when the cytoplasts are washed free of the steroid, in contrast to the case with intact cells. In these same experiments, we have also shown that tyrosine aminotransferase activity of cytoplasts is neither induced by dexamethasone nor deinduced by removal of steroid from the incubation medium, confirming previous reports (7,10,12) .…”

Section: Discussionsupporting

confidence: 92%

“…It had been reported previously that dexamethasone did not induce tyrosine aminotransferase activity in rat hepatoma cells enucleated while attached to plastic plates, demonstrating the essential role of the nucleus in the steroid-mediated induction of this enzyme (7,10,12). The data of Table II illustrate the effect of dexamethasone on tyrosine aminotransferase induction in our cytoplast preparations and confirm these earlier reports .…”

Section: Aib Transport In Htc Cytoplastssupporting

confidence: 91%

“…There is evidence that protein degradation in HTC cells is dependent upon protein synthesis and can be blocked by cycloheximide (5,9). In addition, in HTC cells enucleation results in a reduction in the rate of degradation of tyrosine aminotransferase and a small number of other unstable proteins (7) . These results imply the involvement of some nuclear component in the turnover of HTC cell proteins.…”

Section: Discussionmentioning

confidence: 99%

“…The recovery of transport is blocked by addition of cycloheximide (16) . Tyrosine aminotransferase activity of cells from which dexamethasone has been removed decreases with a half-time of ~2 .5 h (7) . We therefore examined the reversibility of the dexamethasone-inhibited AM transport in cytoplasts prepared from dexamethasone-treated cells.…”

Section: Reversibility Of Dexamethasone Inhibition Of Transportmentioning

confidence: 99%

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Glucocorticoid regulation of amino acid transport in anucleate rat hepatoma (HTC) cells.

McDonald¹,

Gelehrter²

1981

The Journal of Cell Biology

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The transport of a-aminoisobutyric acid (AIB) by rat hepatoma tissue culture (HTC) cells is rapidly and reversibly inhibited by dexamethasone and other glucocorticoids . To investigate the role of the nucleus in the regulation of transport and to determine whether steroid hormones or steroid-receptor complexes may have direct effects on cytoplasmic or membrane functions, we have examined the regulation of transport by dexamethasone in anucleate HTC cells. Cytoplasts prepared from suspension cultures of HTC cells fully retain active transport of AIB with the same kinetic properties as intact cells. However, the uptake of AIB is not inhibited by dexamethasone or other corticosteroids . Neither is the inhibited rate of transport, manifested by cytoplasts prepared from dexamethasone-treated cells, restored to normal upon removal of the hormone . Anucleate cells exhibit specific, saturable binding of [3H]dexamethasone ; however, the binding is reduced compared with that of intact cells. The nucleus is thus required for the glucocorticoid regulation of amino acid transport in HTC cells .

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Section: Discussionsupporting

confidence: 92%

Section: Aib Transport In Htc Cytoplastssupporting

confidence: 91%