The primary structure of rat ribosomal protein L37a

Identification of cytokine-induced nuclear factor-kappaB target genes in ovarian and breast cancer cells

NF-kappaB is a pleiotropic transcription factor controlling the expression of many genes and viruses. NF-kappaB plays a role in immune response, cellular adhesion or acute phase response. It also inhibits apoptosis and favors cancer cell survival. We studied the expression of genes controlled by NF-kappaB in ovarian and breast adenocarcinoma cancer cells. We stably transfected OVCAR-3 and MCF7 A/Z cells with an expression vector coding for the mutated inhibitor IkappaBalpha, which sequesters NF-kappaB in the cytoplasm. We stimulated control and IkappaBalpha expressing cells with IL-1beta or TNF-alpha and extracted the RNA, which was reverse-transcribed and hybridized to DNA microarrays. Several of the genes identified were not known as NF-kappaB target genes. Among them, we confirmed the differential expression of ephrin-A1 and caveolin-1 by quantitative real-time polymerase chain reaction. Our results showed an NF-kappaB-dependent induction of ephrin-A1 and caveolin-1 mRNAs after stimulation with TNF-alpha and IL-1beta, confirming that NF-kappaB controls target genes implied in tumor angiogenesis and cell transformation.

An enhancer trap line identifies the Drosophila homolog of the L37a ribosomal protein

A gene identified from an enhancer trap screen is shown to encode the Drosophila melanogaster homolog of the L37a ribosomal protein. The predicted 92 amino-acid sequence of this protein is 78% identical to mammalian L37a proteins, and contains a conserved Cys-X2 Cys-X14-Cys-X2-Cys zinc finger motif that may be involved in interactions with ribosomal RNA. The Drosophila L37a homolog is a single copy gene comprised of four exons and is ubiquitously expressed throughout the animal. Cytological localization reveals that Drosophila L37a maps to position 25C1-3, very near the previously described Minute mutation M(2)25C.

The cDNA for the ubiquitin-52-amino-acid fusion protein from rat encodes a previously unidentified 60 S ribosomal subunit protein

Rat cDNAs for a 52-amino-acid ribosomal protein (CEP52) that is typically formed as a ubiquitin fusion protein, were cloned following reverse transcription and PCR amplification. CEP52 sequence conservation is demonstrated by the similarity of the human and rat cDNA sequences and the identity of the predicted proteins. Amplification of rat cDNA with a primer specific for the 3' non-coding region of the CEP52 gene, in combination with a consensus primer for the 5' end of the ubiquitin coding sequence, provided evidence that the rat CEP52 gene is fused to a ubiquitin reading frame. Direct sequence analysis of this PCR product confirmed the in-frame fusion of a ubiquitin coding sequence to the rat CEP52 gene. Antibodies against a synthetic CEP52 peptide were used to show that expressed CEP52 is associated with the 60 S ribosomal subunit, and that is is not linked to ubiquitin. The quantity of CEP52 found in different tissues is quite variable, but appears to correspond to the amount of ribosomes present. Although the human, Arabidopsis thaliana and Nicotiana tabacum CEP52 genes contain introns within the CEP52 coding region, the rat CEP52 coding sequence appears to lack insertions.

Human ribosomal protein L37a: cloning of the cDNA and analysis of differential gene expression in tissues and cell lines

A cDNA corresponding to human ribosomal protein L37a (hL37a) was obtained by screening a SHSY5Y neuroblastoma library. The full-length cDNA contained 366 nucleotides (nt) in addition to a poly(A) tail. The pyrimidine-rich sequence, CTTTCT, that is common to many ribosomal protein-encoding cDNAs was present at the 5' terminus. The nt sequence displayed 85% identity with rat L37a (rL37a) cDNA. The predicted protein contains 92 amino acids with a M(r) of 10,277, is highly basic, and has 100% sequence identity with rL37a. A putative zinc-finger domain is present in the central region of the protein. Human lymphocytes and several human cell lines express hL37a mRNA at significantly higher levels than the rat cell lines and rat tissues tested. The hL37a gene does not contain introns.

Zinc finger-like motifs in rat ribosomal proteins S27 and S29

The primary structures of the rat 40S ribosomal subunit proteins S27 and S29 were deduced from the sequences of nucleotides in recombinant cDNAs and confirmed by determination of amino acid sequences in the proteins. Ribosomal protein S27 has 83 amino acids and the molecular weight is 9,339. Hybridization of cDNA to digests of nuclear DNA suggests that there are 4-6 copies of the S27 gene; the mRNA for the protein is about 620 nucleotides in length. Ribosomal protein S29 has 55 amino acids and the molecular weight is 6,541. There are 14-17 copies of the S29 gene and its mRNA is about 500 nucleotides in length. Rat ribosomal protein S29 is related to several members of the archaebacterial and eubacterial S14 family of ribosomal proteins. S27 and S29 have zinc finger-like motifs as do other proteins from eukaryotic, archaebacterial, eubacterial, and mitochondrial ribosomes. Moreover, ribosomes and ribosomal subunits appear to contain zinc and iron as well.