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At least 19 recordsLinked to original sources
PubMed2026

RPL32: From housekeeping gene to potential biomarker and therapeutic target in cancer and multiple system diseases.

Ribosomal protein L32 (RPL32) is a core component of the 60S ribosomal subunit and a stable reference gene. Mounting evidence shows that RPL32 is upregulated in hepatocellular carcinoma, lung cancer, breast cancer, prostate cancer, and other malignancies, correlating with poor prognosis. RPL32 promotes cancer cell proliferation, invasion, and progression partly through the MDM2-p53-autophagy axis, and its expression is regulated by promoter methylation, copy number variations, and transcription factors. RPL32 represents a promising prognostic biomarker and candidate intervention target for cancer. However, its clinical translation requires further validation regarding intervention efficacy, systemic toxicity, druggability, and companion diagnostics. This narrative review summarizes the structure, function, and regulatory mechanisms of RPL32, emphasizes its oncogenic roles and translational potential in cancer, and briefly describes its pathological implications in non-cancer diseases, providing a framework for future cancer research.

Humans↗
PubMed1989

Localization of transcriptional regulatory elements and nuclear factor binding sites in mouse ribosomal protein gene rpL32.

The DNA sequences required for expression of the ribosomal protein gene rpL32 were identified by transient-expression assays of chimeric rpL32-chloramphenicol acetyltransferase genes. These studies showed that maximal rpL32 expression requires sequences in a 150- to 200-base-pair region spanning the transcriptional start site. Three discrete regions of importance were identified: one between positions -79 and -69 and two others located downstream of the transcriptional start site. Progressive 5' or 3' deletions caused stepwise decreases in expression, which suggested a complex interplay of redundant or compensatory elements. Gel mobility shift assays were used to identify trans-acting nuclear factors which bind to segments of the rpL32 promoter that are known to be important for transcription. Evidence for several distinct nuclear factors is presented. The binding sites for these factors were localized to the following regions: -79 to -69, -36 to -19, -19 to +11, +11 to +46 in exon I, and within the first 31 base pairs of intron 1. One of these factors may bind to multiple sites within the promoter region. Interestingly, the factor that binds to a sequence motif in the first exon also binds to similar motifs in a comparable region of the c-myc gene.

Animals↗
PubMed1989

Importance of introns for expression of mouse ribosomal protein gene rpL32.

The importance of intronic sequences for expression of the mouse ribosomal protein gene rpL32 was evaluated by transfection experiments with a series of mutant constructs in which one or more of the three rpL32 introns was totally or partially deleted. When transiently transfected into monkey kidney (COS) cells or stably transfected into mouse L cells, a mutant that lacked all three introns was completely inactive. Constructs that contained intron 1, either alone or in combination with another intron, were expressed as efficiently as was the normal intact rpL32 gene. Constructs that lacked intron 1 but contained another spliceable intron, even one from a foreign gene, were expressed at about 10 to 20% of the maximum level. These results indicated that intron 1 contains an element that increases the level of expression by 5- to 10-fold. A comparison of internal deletion mutants localized the element to within the first 27 base pairs of intron 1. Nuclear run-on experiments with stably transfected COS cells demonstrated that this element functions at the transcriptional level. The element was inactive when translocated to a position upstream of the transcriptional start site or to a position within intron 3, which indicated that it does not have the properties of a typical enhancer. From these and other results, we conclude that introns have both a general and a specific role in rpL32 expression. The general role, which can be satisfied by any spliceable intron, is to ensure an efficient yield of RNA transcripts. The specific role is uniquely attributable to intron 1, which contains a transcriptional regulatory element near its 5' end.

Animals↗
PubMed1992

Active transcription from a promoter positioned within the coding region of a divergently oriented gene: the tobacco chloroplast rpl32 gene.

A new transcription unit has been identified and characterized in the small single-copy region of tobacco chloroplast DNA. A primary transcript (1550 nucleotides) spanning the entire transcription unit contains no significant open reading frames (ORFs), other than ORF55, recently identified as the gene encoding the ribosomal protein CL32 (rpl32). The leader sequence extends 1101 nucleotides from the rpl32 initiation codon. Primer extension and in vitro capping experiments in combination with ribonuclease protection assays, revealed a promoter situated more than 322 bp inside the coding region of ndhF, which is divergently oriented with respect to rpl32. A canonical Pribnow-box is found just upstream of the transcription start site, but a typical -35 motif was not detected. This is the first internal divergent promoter to be characterized in the chloroplast genome.

Autoradiography↗
PubMed1992

A downstream sequence of the rpL32 promoter competes with the glucocorticoid responsive element for a protein factor.

The murine ribosomal protein (rp) L32 gene contains essential promoter sequences located both upstream and downstream of the cap site. A combination of gel mobility shift, UV cross-linking, and cell-free transcription assays were used to analyze the interaction of factors binding to a downstream element (located at position +25 to +37). The rpL32 downstream element identified polypeptides (transcription factors) ranging in size from 45 to 25 kilodaltons (kDa). Four base pair changes in the wild-type sequence of the downstream element eliminated binding. An oligonucleotide containing the glucocorticoid responsive element sequence competed specifically for the 45-kDa protein in both the gel mobility shift assay and in the UV cross-linking studies. Our data also indicate that the downstream binding factors contribute to cell-free transcription of the rpL32 gene.

Animals↗
PubMed1992

Yeast transcription factor IID participates in cell-free transcription of a mammalian ribosomal protein TATA-less promoter.

We analysed transcription of the gene for the ribosomal protein (rp) L32 of the mouse, which is transcribed in mouse L1210 nuclear extracts in vitro. The rpL32 gene lacks a canonical TATA box. Hence it has been suggested that this gene has an alternative transcription pathway not requiring transcription factor IID (TFIID). Selective inactivation of TFIID in nuclear extract completely abolished the transcription of rpL32 in vitro. Selective inactivation was restored by the addition of cloned and purified yeast TFIID (yTFIID), indicating that this TATA-less rpL32 promoter utilizes TFIID for its transcription initiation. Furthermore, addition of an oligonucleotide-containing TATA sequence interfered with the rpL32 transcription and this was overcome by the addition of yTFIID. To further examine the stage of involvement of TFIID in rpL32 transcription, TATA oligonucleotide was added to nuclear extract before and after the formation of the transcription complex. The results reveal that TFIID associates with the pre-initiation complex and that this complex is largely resistant to added TATA oligonucleotide. Our results show, for the first time, that the TATA-less rpL32 gene utilizes TFIID for transcription initiation.

Animals↗
PubMed1985

A processed pseudogene in an intron of the HLA-DP beta 1 chain gene is a member of the ribosomal protein L32 gene family.

A sequence in an intron of the human HLA-DP beta 1 gene was identified by its homology to the gene encoding ribosomal protein L32 (rpL32). It lacked introns indicating that it was derived from a processed rpL32 mRNA transcript. A human cDNA clone encoding rpL32 was isolated and compared to this human pseudogene and to several related mouse sequences, one of which is contained in an intron of the murine dihydrofolate reductase gene. Comparison of these sequences revealed that they were more related within species than between, suggesting that they became inserted in the genome after man and mouse diverged.

Animals↗
PubMed1987

The yeast ribosomal protein L32 and its gene.

The yeast ribosomal protein gene RPL32 of Saccharomyces cerevisiae is of particular interest for two reasons: 1) it is adjacent to another ribosomal protein gene, RP29, whose divergent transcription may be driven from the same control sequences, and 2) it appears that the splicing of its transcript is regulated by the product of the gene, ribosomal protein in L32. RPL32 has been analyzed in detail. It is essential for cell growth. Its sequence predicts L32 to be a protein of 105 amino acids, somewhat basic near the NH2 terminus, rather acidic near the COOH terminus, and homologous to ribosomal protein L30 of mammals. The reading frame has been confirmed by partial NH2-terminal analysis of L32. The nucleotide sequence also predicts an intron of 230 nucleotides, which begins with the unusual sequence GTCAGT and ends 40 nucleotides downstream of the consensus sequence TAC-TAAC. The intron has been confirmed by determination of the sequence of a cDNA clone. Transcription initiates 58 nucleotides upstream of the AUG initiation codon, and the polyadenylation site occurs 100 nucleotides downstream of the termination codon. Regulation of the transcription of ribosomal protein genes has been linked to two related consensus sequences. Analysis of the intergenic region between RP29 and RPL32 reveals three copies of these sequences. A deletion removing all three sequences reduces synthesis of a L32-LacZ fusion protein by more than 90%. Some residual activity, however, remains.

Amino Acid Sequence↗
PubMed1991

Structural basis for the regulation of splicing of a yeast messenger RNA.

In S. cerevisiae, ribosomal protein L32 regulates the splicing of the transcript of its own gene, RPL32. We have identified an RNA structure within the transcript that is responsible for this regulation. Initial deletions limited essential sequences to the 5' exon and the first few nucleotides of the intron. To take advantage of phylogenetic comparison of RNA structures, RPL32 was cloned from the closely related species, Kluyveromyces lactis. The splicing of its transcript is similarly regulated. Sequences conserved between the S. cerevisiae and K. lactis transcripts suggested a structure involving base pairing of a region encompassing the 5' splice site with another near the 5' end of the transcript. Analysis of numerous site-directed mutations supports this structure. We infer that stabilization of this structure by L32 inhibits splicing by precluding the interaction of U1 RNA with the 5' splice site.

Base Sequence↗
PubMed1989

An element downstream of the cap site is required for transcription of the gene encoding mouse ribosomal protein L32.

To identify the elements that regulate transcription of the mouse gene encoding ribosomal protein L32 (rpL32), we transfected monkey kidney (COS or CV-1) cells with mutants bearing progressive 5' deletions or an internal deletion in exon I and measured their transient expression by S1 nuclease protection analysis. When the mutant genes were tested in the vector pi SVHSplac, which contains a short segment of the oriregion of simian virus 40, maximum expression was observed with as little as 36 base pairs of 5' flanking sequence, and the mutant bearing the exon I deletion was expressed very efficiently. However, when the genes were tested in a simple prokaryotic (pUC) vector, the expression was increased 3- to 4-fold by sequences between -36 and -159, and the exon I segment was absolutely required for expression. Gel mobility-shift and methylation interference analyses revealed that a nuclear factor specifically binds to a GGCTGCCATC sequence within this exon I segment. These results, taken together with other recent findings, indicate that the elements involved in transcriptional regulation of the rpL32 gene are distributed over a 200-base-pair region that spans the cap site. The contributions of some of these elements are apparently masked in the presence of simian virus 40 ori-region elements.

Animals↗
PubMed1989

Equipotent mouse ribosomal protein promoters have a similar architecture that includes internal sequence elements.

The promoters of the mouse ribosomal protein genes rpL30, rpL32, and rpS16 are of equal strength, as indicated by in vivo measurements of polymerase loading and by their relative efficiency in driving the expression of a linked reporter gene. The equipotency of these promoters appears to derive from a remarkably similar architecture in which five or more elements are distributed over a 200-bp region that spans a polypyrimidine-embedded cap site. Three trans-acting factors are shared by the rpL30 and rpL32 promoters, one of which, delta, recognizes a common CNGCCATCT motif in the first (untranslated) exons. Site-specific mutagenesis demonstrated that delta-factor binding is critical for rpL30 promoter function. The repeated occurrence of this novel promoter architecture among ribosomal protein genes with very different coding specificities is most readily explained by convergent evolution.

Animals↗
PubMed1992

Visualization of a mammalian transcription initiation complex.

Various proteins required for the initiation of eukaryotic gene transcription by RNA polymerase II have been identified and characterized, but little is known about their organization into a functional unit. Here, we describe the appearance of the murine ribosomal protein (rp) L32 gene transcription initiation complex as determined by transmission electron microscopy. Using a fractionated nuclear extract enriched for transcription factors necessary for rpL32 gene transcription in vitro and a DNA fragment containing the rpL32 gene promoter, the transcription initiation complex was imaged by standard transmission electron microscopy. Quantitative image analysis demonstrated that the complex is a multilobed structure whose two-dimensional projections are approximately 24 x 34 nm in size. Looping of the DNA seen in these images suggests that the proteins residing at the promoter region associate with proteins several hundred base pairs distant to the RNA start site, with bending of the DNA allowing these interactions to occur.

Animals↗
PubMed2026

Plastome evolution and phylogenomic relationships in Ajuga (Lamiaceae, Ajugoideae).

BACKGROUND: Ajuga is currently known to include approximately 69 species, with a combined distribution extending throughout Eurasia, Africa, and Australia. Its popularity and significance are largely based on an extensive history of medicinal and horticultural use. It is divided into two sections based on morphological characters, and this sectional classification is also reflected in pronounced geographic patterns. Although previous studies have largely focused on Ajuga sect. Ajuga in East Asia, A. sect. Chamaepithys, which ranges from the Mediterranean to Central Asia, remains insufficiently sampled, thereby limiting a comprehensive understanding of infrageneric sectional relationships within the genus. Here, we generated complete plastid genomes for 12 species representing both sections of the genus and used these data to characterize plastome structure and infer evolutionary relationships. RESULTS: In this study, 21 Ajuga plastomes were analyzed, including 12 newly sequenced plastomes and 9 previously published plastomes representing 19 species. Comparative analyses showed that all plastomes exhibited a highly conserved quadripartite structure, with genome sizes ranging from 149,963 to 150,740 bp and GC contents varying from 38.2% to 38.3%. Each plastome contained 133 genes, including 88 protein-coding genes, 37 transfer RNA genes, and 8 ribosomal RNA genes. The boundaries between the inverted repeat (IR) and single-copy (SC) regions were also highly conserved across species. In addition, 796 simple sequence repeats (SSRs), 874 long repeat sequences (LRSs), and 12 highly variable regions (ccsA-ndhD, ndhF-rpl32, petA-psbJ, rpl32-trnL-UAG, rps2-rpoC2, trnH-GUG-psbA, trnK-UUU-rps16, trnP-UGG-psaJ, trnT-UGU-trnL-UAA, ycf15-trnL-CAA, ndhF, and ycf1) were identified among the 21 plastomes. Phylogenetic analyses based on four datasets and conducted using Maximum Likelihood and Bayesian Inference recovered two major clades corresponding to the traditionally recognized sectional classification, with one distributed from the Mediterranean to Central Asia and the other in East Asia. CONCLUSION: This study represents the most comprehensive plastome-based sampling of Ajuga to date, including representative species from the Mediterranean, Central Asia, and East Asia. Our results have significantly enhanced our understanding of its infrageneric relationships. The plastome resources generated in this study provide a valuable foundation for future research on species delimitation, phylogeny, and the evolutionary history of Ajuga.

Phylogeny↗
PubMed2026

Insights into phylogenetic relationships of Veronica species (Plantaginaceae) based on comparative chloroplast genomics.

INTRODUCTION: Veronica L. is one of the most species-rich genera in Plantaginaceae and several species have medicinal, horticultural, or ecological value. METHODS: In this study, the complete chloroplast genomes of three Veronica species were assembled and annotated using Illumina sequencing data. RESULTS: The plastomes exhibited a typical quadripartite structures, with total lengths of 150,202 bp for Veronica biloba L., 151,159 bp for Veronica ciliata Fisch. and 151,098 bp for Veronica vandellioides Maxim. Each genome contained 130-132 unique genes, including 86-87 protein-coding genes, 36-37 tRNA genes, and 8 rRNA genes. Comparative analyses of 24 Veronica plastomes indicated that the IR/SC junctions were largely conserved, although slight boundary shifts occurred around rps19, ndhF, and ycf1. Forward, palindromic, complement, and reverse repeats were detected, and A/T mononucleotide repeats were the dominant SSR type. Nucleotide diversity analysis identified rpl32-trnL, trnK-rps16, rpl32, ycf1, ndhF, accD, matK, and rpoB as highly variable regions. Phylogenetic analyses recovered Veronica as a well-supported monophyletic lineage and clarified the plastid positions of the three newly sequenced species. Divergence time estimation suggested that the estimation suggested of Veronica was around 14.9 Ma, with V. biloba, V. ciliata and V. vandellioides diverging approximately 3.9 Ma, 0.6 Ma, and 6.9 Ma, respectively. DISCUSSION: Because the analyses were based on plastid genomes, the inferred topology should be interpreted as chloroplast phylogenetic evidence rather than a complete species-history reconstruction. These results provide plastome resources and molecular evidence for taxonomy, species identification, and future evolutionary studies of Veronica.

Plantaginaceae↗
PubMed1992

Multivariate statistical analysis of electron micrographs of a mammalian transcription initiation complex.

We describe the appearance of the murine ribosomal protein (rp) L32 gene transcription initiation complex as determined by electron image analysis. Using a fractionated nuclear extract enriched for transcription factors necessary for rpL32 gene transcription in vitro and a DNA fragment containing the rpL32 gene promoter, the transcription initiation complex was prepared and viewed by standard transmission electron microscopy. Image analysis demonstrated that the complex was a multilobed structure.

Cells, Cultured↗
PubMed1992

Combination of in vitro capping and ribonuclease protection improves the detection of transcription start sites in chloroplasts.

A primary transcript from the chloroplast rpl32 gene was labelled at its 5' end using a capping enzyme and [alpha-32P]GTP followed by hybridization to a cold RNA probe. A RNase protection assay gave a clear protected band and its initiation site of transcription could thus be estimated, which had not been possible by using DNA probes. The combination of in vitro capping and RNase protection is an excellent method for mapping transcription initiation sites on the chloroplast genome and shows a high improvement relative to the DNA-employing strategies.

Chloroplasts↗
PubMed1990

Chloroplast ribosomal protein L32 is encoded in the chloroplast genome.

The 50 S subunit of chloroplast ribosomes was prepared from tobacco leaves. The proteins were fractionated and the N-terminal amino acid sequence of a 14 kDa protein was determined. This sequence matches the N-terminal sequence deduced from ORF55 located between ndhF and trnL on the small single-copy region of tobacco chloroplast DNA. The deduced protein shows homology to E. coli and B. stearothermophilus L32 proteins, and it has been named as CL32 and ORF55 as rpl32. The tobacco chloroplast genome therefore contains 21 different ribosomal protein genes.

Amino Acid Sequence↗
PubMed1992

A positive regulator of the ribosomal protein gene, beta factor, belongs to the ETS oncoprotein family.

The beta factor, which interacts with the rpL32 promoter, binds to the sequence 5'-GAGCCGGAAGTG and trans-activates this gene. Comparison of the DNA sequences bound by the beta factor with those bound by other known DNA-binding proteins revealed that the ETS proteins interact with similar DNA sequences. Consequently we have examined the relationship of the beta factor to the several ETS proteins so far reported. Antibody and oligonucleotide competition experiments, performed by using electrophoretic shift analysis, revealed that the beta factor contains ETS epitopes and that it is immunologically related to both of the GA-binding proteins (GABPs), implying that the beta factor may consist of two separate protein subunits.

Amino Acid Sequence↗