The Length of 5′-Untranslated Leader Sequences Influences Distribution of 3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase mRNA in Polysomes: Effects of Lovastatin, Oxysterols, and Mevalonate

Gayen, Apurba K.; Peffley, Dennis M.

doi:10.1006/abbi.1995.1491

Cited by 19 publications

(15 citation statements)

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“…Because the postulated self-priming occurs within the segment of antisense RNA corresponding to the 5'-untranslated region of globin mRNA, the resulting sense strand would retain an intact coding capacity, as well as the 3'-untranslated beneficial for the translational efficiency of mRNA (20,21). Principally, similar self-priming might occur within a portion of an antisense molecule corresponding to the coding region of an mRNA, thus generating sense strand with truncated coding region.…”

Section: Discussionmentioning

confidence: 99%

Antisense globin RNA in mouse erythroid tissues: structure, origin, and possible function.

Volloch

Schweitzer

Rits

1996

Proc. Natl. Acad. Sci. U.S.A.

148

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The aim of the experiments described in this paper was to test for the presence of antisense globin RNA in mouse erythroid tissues and, if found, to characterize these molecules. The present study made use of a multistep procedure in which a molecular tag is attached to cellular RNA by ligation with a defined ribooligonucleotide. The act of ligation preserves the termini of RNA molecules, which become the junctions between cellular RNAs and the ligated ribooligonucleotide. It also unambiguously preserves the identity of cellular RNA as a sense or antisense molecule through all subsequent manipulations. Using this approach, we identified and characterized antisense 8-globin RNA in erythroid spleen cells and reticulocytes from anemic mice. We show in this paper that the antisense globin RNA is fully complementary to spliced globin mRNA, indicative of the template/transcript relationship. It terminates at the 5' end with a uridylate stretch, reflecting the presence of poly(A) at the 3' end of the sense globin mRNA. With respect to the structure of their 3' termini, antisense globin RNA can be divided into three categories: full-size molecules corresponding precisely to globin mRNA, truncated molecules lacking predominantly 14 3'-terminal nucleotides, and extended antisense RNA containing 17 additional 3'-terminal nucleotides. The full-size antisense globin RNA contains two 14-nt-long complementary sequences within its 3'-terminal segment corresponding to the 5'-untranslated region of globin mRNA. This, together with the nature of the predominant truncation, suggests a mechanism by which antisense RNA might give rise to new sensestrand globin mRNA.Earlier, we reported the detection and partial characterization of antisense globin RNA in murine erythroleukemia (MEL) cells (1). This RNA appeared to be a complement of the corresponding sense globin mRNA. Indeed, antisense globin RNA had an electrophoretic mobility similar to that of globin mRNA, and it hybridized with probes corresponding to the 5'-and 3'-terminal segments of globin mRNA, as well as with probes corresponding to the entire globin mRNA. Experiments with whole cells (1) and with cytoplasts obtained by enucleation of MEL cells (2) indicated that antisense globin RNA, as well as its sense counterpart, is synthesized in the cytoplasm and suggested that it may serve as an intermediate in cytoplasmic globin mRNA synthesis by RNA-dependent RNA polymerase, an activity that has been detected in erythroleukemia cells (1), as well as in normal reticulocytes (3). If such a process indeed occurred physiologically, one would expect (i) to find the antisense globin RNA molecule not only in MEL cells but also in animal erythroid tissues, and (ii) that these molecules are precise complements of their sense counterparts. Accordingly, the present study was undertaken to test for the occurrence of antisense globin RNA in erythroid cells from mouse tissues and to analyze its primary structure, The publication costs of this article were defrayed in part by page charge...

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Section: Discussionmentioning

confidence: 99%

Antisense globin RNA in mouse erythroid tissues: structure, origin, and possible function.

Volloch

Schweitzer

Rits

1996

Proc. Natl. Acad. Sci. U.S.A.

148

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“…These results suggest that the effects of 22R and RA on APP processing might depend not only on ABCA1-mediated cholesterol efflux but on additional factors. Oxysterols regulate other genes affecting cholesterol homeostasis, including ABCG1, sterol regulatory element-binding protein processing, and hydroxymethylglutaryl-CoA reductase (60,61). Furthermore, oxysterols and cholesterol decrease the expression of low density lipoprotein receptors including low density receptor-related protein (LRP) (62).…”

Section: Distribution and Localization Of Abca1 In Ratmentioning

confidence: 99%

22R-Hydroxycholesterol and 9-cis-Retinoic Acid Induce ATP-binding Cassette Transporter A1 Expression and Cholesterol Efflux in Brain Cells and Decrease Amyloid β Secretion

Koldamova

Lefterov

Ikonomović

et al. 2003

Journal of Biological Chemistry

224

209

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The ATP-binding cassette transporter A1 (ABCA1) is a major regulator of peripheral cholesterol efflux and plasma high density lipoprotein metabolism. In adult rat brain we found high expression of ABCA1 in neurons in the hypothalamus, thalamus, amygdala, cholinergic basal forebrain, and hippocampus. Large neurons of the cholinergic nucleus basalis together with CA1 and CA3 pyramidal neurons were among the most abundantly immunolabeled neurons. Glia cells were largely negative. Because cholesterol homeostasis may have an essential role in central nervous system function and neurodegeneration, we examined ABCA1 expression and function in different brain cell types using cultures of primary neurons, astrocytes, and microglia isolated from embryonic rat brain. The basal ABCA1 mRNA and protein levels detected in these cell types were increased markedly after exposure to oxysterols and 9-cis-retinoic acid, which are ligands for the nuclear hormone liver X receptors and retinoic X receptors, respectively. Functionally, the increased ABCA1 expression caused by these ligands was followed by elevated apoA-I-and apoE-specific cholesterol efflux in neurons and glia. In non-neuronal and neuronal cells overexpressing a human Swedish variant of amyloid precursor protein, 22R-hydroxycholesterol and 9-cis-retinoic acid induced ABCA1 expression and increased apoA-I-mediated cholesterol efflux consequently decreasing cellular cholesterol content. More importantly, we demonstrated that these ligands alone or in combination with apoA-I caused a substantial reduction in the stability of amyloid precursor protein C-terminal fragments and decreased amyloid ␤ production. These effects of 22R-hydroxycholesterol may provide a novel strategy to decrease amyloid ␤ secretion and consequently reduce the amyloid burden in the brain.

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“…p␤Gal-neo was constructed by ligating the 3.47-kb ␤-galactosidase fragment from pNASS␤ (CLONTECH; Palo Alto, CA) into the NotI site of pcDNA3. pRPS17 (17) was provided by D. Peffley (Finch University of Health Sciences/the Chicago Medical School), and full-length cDNA of human LDLR (44) was provided by E. Leitersdorf (Hebrew University/ Haddassah Medical School).…”

Section: -Hydroxycholesterol Was From Steraloids (Wilton Nhmentioning

confidence: 99%

“…RNase Protection Assay-To prepare an antisense RNA probe for HMGR, we amplified a 206-base pair DNA fragment from the cytoplasmic domain of Chinese hamster HMGR using pDGS6 plasmid as the template and oligonucleotides 5Ј-CGGAATTCGTGCCTGGATGGTA-AAGAG-3Ј ( (46) 32 P-labeled antisense RNA probe for the S17 ribosomal protein was transcribed using the AvaII-digested pRPS17 plasmid (17). Total cellular RNA was extracted with RNAzol B reagent (Biotecx Laboratories, Houston, TX) and hybridized overnight at 50°C with gel-purified antisense probes, accord-ing to the instructions provided by the manufacturer (RPAII TM kit; Ambion).…”

Section: -Hydroxycholesterol Was From Steraloids (Wilton Nhmentioning

confidence: 99%

Impaired Regulation of 3-Hydroxy-3-methylglutaryl-Coenzyme A Reductase Degradation in Lovastatin-resistant Cells

Ravid

Avner

Polak‐Charcon

et al. 1999

Journal of Biological Chemistry

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L-90 cells were selected to grow in the presence of serum lipoproteins and 90 M lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR). L-90 cells massively accumulate HMGR, a result of >10-fold amplification of the gene and 40-fold rise in mRNA, and also overexpress other enzymes of the mevalonate pathway. Western blot and promoter-luciferase analyses indicate that transcriptional regulation of sterol-responsive genes by 25-hydroxycholesterol or mevalonate is normal. Yet, none of these genes is regulated by lipoproteins, a result of severe impairment in the low density lipoprotein receptor pathway. Moreover, L-90 cells do not accelerate the degradation of HMGR or transfected HMGal chimera in response to 25-hydroxycholesterol or mevalonate. This aberrant phenotype persists when cells are grown without lovastatin for up to 37 days. The inability to regulate HMGR degradation is not due to its overproduction since in LP-90 cells, which were selected for lovastatin resistance in lipoprotein-deficient serum, HMGR is overexpressed, yet its turnover is regulated normally. Also, the rapid degradation of transfected ␣ subunit of T cell receptor is markedly retarded in L-90 cells. These results show that in addition to gene amplification and overexpression of cholesterogenic enzymes, statin resistance can follow loss of regulated HMGR degradation. Mevalonate (MVA)1 is the first committed precursor for biosynthesis of cholesterol and a variety of essential nonsterol isoprenoids such as ubiquinone, dolichol, isopentenyl-modified tRNAs, side chain of heme A, and the farnesyl and geranylgeranyl moieties of many cellular proteins (1-4). Cells must constantly synthesize MVA yet avoid accumulation of these products to toxic levels. This problem is especially acute in mammalian cells since cholesterol, the bulk end product of the MVA pathway, can be obtained also by receptor-mediated endocytosis of low density lipoproteins (LDL). Classical experiments by Brown and Goldstein (5) and their co-workers have demonstrated that the increase in intracellular levels of LDLderived cholesterol triggers a feedback response that downregulates the expression of the LDL receptor (LDLR) and represses endogenous cholesterol synthesis. Conversely, depletion of cholesterol leads to increased surface expression of LDLR and enhanced rate of cholesterol synthesis (6).The major regulatory step in the MVA pathway is the conversion of HMG-CoA to MVA by the enzyme HMGR. Early experiments have shown that cultured mammalian cells maintain low rate of endogenous MVA production even in the presence of saturating amounts of sterols. HMGR activity can be fully repressed only if the synthesis of MVA-derived nonsterol is allowed, suggesting that HMGR activity (hence MVA synthesis) is controlled through multivalent feedback regulation by sterol and nonsterol MVA-derived metabolite(s) (7). These studies were greatly advanced by the discovery of statins, potent HMGR inhibitors, such as compactin and lovastatin (8, 9). When naive cells are...

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The Length of 5′-Untranslated Leader Sequences Influences Distribution of 3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase mRNA in Polysomes: Effects of Lovastatin, Oxysterols, and Mevalonate

Cited by 19 publications

References 0 publications

Antisense globin RNA in mouse erythroid tissues: structure, origin, and possible function.

Antisense globin RNA in mouse erythroid tissues: structure, origin, and possible function.

22R-Hydroxycholesterol and 9-cis-Retinoic Acid Induce ATP-binding Cassette Transporter A1 Expression and Cholesterol Efflux in Brain Cells and Decrease Amyloid β Secretion

Impaired Regulation of 3-Hydroxy-3-methylglutaryl-Coenzyme A Reductase Degradation in Lovastatin-resistant Cells

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