Regulation of the prereplicative changes in the synthesis and transport of messenger and ribosomal RNA in regenerating livers of normal and hypocalcemic rats

Pr, Walker; Jf, Whitfield

doi:10.1002/jcp.1041080317

Cited by 20 publications

(20 citation statements)

References 36 publications

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“…Using hybridization studies with [3H]-poly(U), we have observed that there is approximately a 25% increase in poly(A)+ containing RNA by 24 hr after unilateral nephrectomy (data not shown). This result is consistent with the reported increases in poly(A)+ mRNA following partial hepatectomy (Atryzek and Fausto, 1979;Glazer, 1976;Walker and Whitfield, 1981) and in mammalian cells stimulated to grow in vitro Johnson et al, 1974). The rapid accumulation of poly(A)+ RNA during the transition from the resting to the growing state may represent an increased efficiency of HnRNA transcription and conversion into cytoplasmic poly(A)+ mRNA (Atryzek and Fausto, 1979).…”

Section: Discussionsupporting

confidence: 91%

Specific gene expression during compensatory renal hypertrophy in the rat

Beer

Zweifel

Simpson

et al. 1987

Journal Cellular Physiology

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The compensatory growth of the kidney which is induced by unilateral nephrectomy is a highly regulated process resulting principally in hypertrophy of the remaining kidney. The events which regulate this process are unknown. We have examined the levels of transcripts for the proto-oncogenes, myc, H-ras, K-ras, and fos, and the cellular genes, H4 histone, ornithine aminotransferase, and gamma-glutamyl transpeptidase, following unilateral nephrectomy in the rat. The pattern of expression of c-myc, c-H-ras, and c-K-ras during compensatory growth of the kidney differs from the pattern of expression of these proto-oncogenes during liver regeneration, in which, unlike the kidney, hyperplasia rather than hypertrophy predominates. The lack of change in the abundance of these proto-oncogene transcripts following unilateral nephrectomy suggests a primary relationship between the expression of these proto-oncogenes and DNA synthesis and indicates there may be separate signals for cell growth, one to double cell size and one to replicate DNA. Increased mRNA transcripts for the enzymes ornithine aminotransferase and gamma-glutamyl transpeptidase were induced in the contralateral kidney after nephrectomy. The time course of expression for these two enzymes differs. The early expression of the gamma-glutamyl transpeptidase gene may indicate an involvement of this glutathione-metabolizing enzyme during renal compensatory growth, while the function of the delayed increase in ornithine aminotransferase transcripts in the remaining kidney is not apparent.

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Section: Discussionsupporting

confidence: 91%

Specific gene expression during compensatory renal hypertrophy in the rat

Beer

Zweifel

Simpson

et al. 1987

Journal Cellular Physiology

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“…The total RNA concentrations both in the nucleus and in the cytoplasm (including cytoplasmic poly A + mRNA) reached to a maximum level within 24 hrs of RH., but their level decreased sharply within 48 hrs of RH. Whereas the nuclear poly A § mRNA level remained unaltered during this period [37,38]. Though, there was no remarkable change in liver specific mRNA transcription rate or its concentration within first 24 hrs of RH.…”

Section: Discussionmentioning

confidence: 77%

Changes in UsnRNA biosynthesis during rat liver regeneration

et al. 1994

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Partial hepatectomy (P.H.) induces a partially synchronized growth response of liver under normal regulation of growth. In this phase changes in cellular morphology, radial distribution pattern of cells and other biological as well as major biochemical changes are well documented [24]. Here, we have shown that the cellular content of UsnRNAs altered during this proliferative phase as well. The level of spliceosomal UsnRNAs (U1, U2, U4-U6) gradually decreased by 30-50 % upto 48 hrs of RH. followed by gradual increase to reach the normal level within one month of R H. The U3 snRNA level on the other hand, was nearly equal to that in normal liver at 48 hrs of RH. but in 24 and 72 hrs of RH. its level was high (4 fold) in contrast to that in other UsnRNAs. Thus, it is clear from our data that the level of all the six UsnRNAs decreased during 48 hrs of RH. compared to that after first 24 hrs. This has been correlated in the kinetics of UsnRNAs' synthesis (in terms of labelling) in isolated hepatocytes, where the rate of labelling of all the six UsnRNAs increased 20-30% in 24 hrs regenerating hepatocytes (R.H.) followed by sharp decrease by 30-50% within next 24 hrs, compared to that in the normal hepatocytes. But from 72 hrs onwards in R.H. the rate of labelling of all the six UsnRNAs again increased by 30-50% (compared to that in normal hepatocytes) followed by decrease of their labelling-rate to reach the normal level in R.H. within one month of RH. Thus, it may be concluded that the changes in UsnRNAs' level during th e proliferative phase of liver regeneration may be either due to the alteration in the rate of synthesis (in terms of labelling) or along with it differential turn over rate; this phenomenon may have some consequences with the regenerative process of liver. (Mol Cell Biochem 141: 71-77, 1994).

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“…The process leading to DNA synthesis is inhibited by indomethacin, but is not mediated by products of arachidonic acid metabolism, while the mitosis-determining process is inhibited by mefenamic acid and gluwcorticoids and mediated by prostaglandins or thromboxane. Although the nature of these separate processes are completely unknown, the mitosis-determining event in liver cells coincides with a transient surge of messenger RNA, which also peaks 2 to 3 hours after partial hepatectomy and is inhibited by indomethacin (Walker and Whitfield, 1981). Whether or not this surge of messenger RNA is related to the mitosisdetermining process or the events leading to DNA synthesis, or both, remains to be determined.…”

Section: Discussionmentioning

confidence: 99%

An early mitosis‐determining event in regenerating rat liver and its possible mediation by prostaglandins or thromboxane

Rixon

Whitfield

1982

Journal Cellular Physiology

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Inhibitors of prostaglandin and thromboxane production such as mefenamic acid, hydrocortisone, and dexamethasone prevented a large proportion of the parenchymal cells of rat liver, proliferatively activated by a two-thirds partial hepatectomy, from entering mitosis without preventing them from initiating or completing DNA synthesis. This specific mitosis-inhibiting action was maximum when the drugs were present during the first few hours after partial hepatectomy. In contrast, indomethacin, another inhibitor of prostaglandin and thromboxane production, maximally inhibited both DNA synthetic and mitotic activities when present during the same early period of prereplicative development, which showed that it had an action not shared by the other inhibitors. Arachidonic acid completely reversed the hydrocortisone- or dexamethasone-induced inhibition of mitotic activity, but it did so only when it was injected between 2 and 3 hours after partial hepatectomy and glucocorticoid injection. Arachidonate's reversal of the hydrocortisone-induced inhibition did not occur in the presence of mefenamic acid. These observations indicate that there is an early, prostaglandin- or thromboxane-mediated, prereplicative process in proliferatively activated hepatocytes which determines their later entry into mitosis and which is separate from the early events leading to DNA synthesis.

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Regulation of the prereplicative changes in the synthesis and transport of messenger and ribosomal RNA in regenerating livers of normal and hypocalcemic rats

Cited by 20 publications

References 36 publications

Specific gene expression during compensatory renal hypertrophy in the rat

Specific gene expression during compensatory renal hypertrophy in the rat

Changes in UsnRNA biosynthesis during rat liver regeneration

An early mitosis‐determining event in regenerating rat liver and its possible mediation by prostaglandins or thromboxane

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