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N Selvamurugan

Publications and source records attributed to N Selvamurugan.

7 recordsLinked to original sources
PubMed1998

Parathyroid hormone regulates the rat collagenase-3 promoter in osteoblastic cells through the cooperative interaction of the activator protein-1 site and the runt domain binding sequence.

Parathyroid hormone induces collagenase-3 gene transcription in rat osteoblastic cells. Here, we characterized the basal, parathyroid hormone regulatory regions of the rat collagenase-3 gene and the proteins involved in this regulation. The minimal parathyroid hormone-responsive region was observed to be between base pairs -38 and -148. Deleted and mutated constructs showed that the activator protein-1 and the runt domain binding sites are both required for basal expression and parathyroid hormone activation of this gene. The runt domain site is identical to an osteoblast-specific element-2 or acute myelogenous leukemia binding sequence in the mouse and rat osteocalcin genes, respectively. Overexpression of an acute myelogenous leukemia-1 repressor protein inhibited parathyroid hormone activation of the promoter, indicating a requirement of acute myelogenous leukemia-related factor(s) for this activity. Overexpression of c-Fos, c-Jun, osteoblast-specific factor-2, and core binding factor-beta increased the response to parathyroid hormone of the wild type (-148) promoter but not with mutation of either or both the activator protein-1 and runt domain binding sites. In summary, we conclude that there is a cooperative interaction of acute myelogenous leukemia/polyomavirus enhancer-binding protein-2-related factor(s) binding to the runt domain binding site with members of the activator protein-1 transcription factor family binding to the activator protein-1 site in the rat collagenase-3 gene in response to parathyroid hormone in osteoblastic cells.

Animals↗
PubMed1997

Intracellular localization and unique conserved sequences of three small nucleolar RNAs.

Three human small nucleolar RNAs (snoRNAs), E1, E2 and E3, were reported earlier that have unique sequences, interact directly with unique segments of pre-rRNA in vivo and are encoded in introns of protein genes. In the present report, human and frog E1, E2 and E3 RNAs injected into the cytoplasm of frog oocytes migrated to the nucleus and specifically to the nucleolus. This indicates that the nucleolar and nuclear localization signals of these snoRNAs reside within their evolutionarily conserved segments. Homologs of these snoRNAs from several vertebrates were sequenced and this information was used to develop RNA secondary structure models. These snoRNAs have unique phylogenetically conserved sequences.

Animals↗
PubMed1995

Intron-encoded small nucleolar RNAs: new RNA sequence variants and genomic loci.

Three small nucleolar RNAs (snoRNAs) whose 5' termini are monophosphorylated, termed E1, E2 and E3, were reported earlier, and E1 and E3 are encoded in pre-mRNA gene introns. In the present work, the ends of these snoRNAs were identified by analysis of terminal mononucleotides, and heterogeneity was observed at the 3' ends of E1 and E2 RNAs. Two new E1 RNA species were detected in HeLa cells by cDNA cloning. Four novel human genomic loci were identified that have E1 or E3 sequence homology. The sequence CTAGAGCACYSAATCTGGAT (where S = C or G and Y = C or T), that is present three nucleotides downstream from the coding region of an E1 RNA-encoding gene, lies in the same location in a different human genomic locus (which has a E1-homology sequence whose expression has not been detected yet), suggesting that this sequence may be functional.

Base Sequence↗
PubMed1993

Genes for E1, E2, and E3 small nucleolar RNAs.

We have found earlier three small nucleolar RNA (snoRNA) species, named E1, E2, and E3, that have unique nucleotide sequences and may participate in ribosome formation. The present report shows that there is a monophosphate at the 5' end of each of these three snoRNAs, suggesting that their 5' termini are formed by RNA processing. E1, E2, and E3 human genomic sequences were isolated. Apparently, the E2 and E3 loci are genes for the main E2 and E3 RNA species, based on their full homology, while the E1 locus is a gene for an E1 RNA sequence variant in HeLa cells. These loci do not have any of the intragenic or flanking sequences known to be functional in other genes. The E1 gene is located within the first intron of the gene for RCC1, a protein that regulates onset of mitosis. There is substantial sequence homology between the human E3 gene and flanking regions, and intron 8 and neighboring exons of the gene for mouse translation initiation factor 4AII. Injection of the human E1, E2, and E3 genes into Xenopus oocytes generated sequence-specific transcripts of the approximate sizes of the respective snoRNAs. We discuss why the available results are compatible with specific transcription and processing occurring in frog oocytes.

Animals↗
PubMed1992

Effect of cytosol on the regulation of expression of myosin heavy chain genes during cardiac hypertrophy.

In vitro translation of RNA transported from the rat heart nuclei has suggested that the transport of translatable messages from hypertrophic heart nuclei is greater than from sham-operated heart nuclei. An increased translation activity was observed in cell-free system with RNA transported from sham-operated heart nuclei in presence of hypertrophic heart cytosol, than from sham-operated heart cytosol. Similar results were obtained when myosin heavy chain (MHC) mRNA in the transported RNA was analyzed by slot-blot hybridization using beta cDNA probe. Immunoprecipitation analysis of the translated products using beta MHC isozyme specific antibody indicated that the increased levels of beta MHC specific mRNA in the RNA transported from sham-operated heart nuclei in presence of hypertrophic heart cytosol than sham-operated heart cytosol. Direct quantitation of alpha and beta MHC messengers by slot-blot hybridization analysis of transported RNA using oligomeric probes corresponding to the 3' untranslated regions of alpha and beta MHC mRNAs revealed that an increased transport of both alpha and beta MHC specific mRNAs from sham-operated heart nuclei in the presence of hypertrophic heart cytosol occurs, of which beta MHC mRNA is more than that of alpha MHC. In contrast, slot-blot hybridization analysis of the radioactive RNA synthesized during transcription in vitro in nuclei obtained from sham-operated as well as hypertrophic hearts has shown an increased synthesis of alpha in sham nuclei and that of beta in hypertrophic heart nuclei. These results suggest that both transcriptional and post-transcriptional regulation may be operative in the expression of alpha and beta MHC genes during the development of cardiac hypertrophy.

Animals↗
PubMed1990

Purification and characterization of a high-molecular-weight protein induced in rat serum during the development of cardiac hypertrophy.

A relatively high-molecular-weight polypeptide was found in rat serum within 6 h after aortic constriction in experimental animals. This polypeptide persists for about 7 days of the postoperative period and disappears at later stage of hypertrophy (40%). Further, fractionation and purification of this protein through DEAE-Sepharose and gel filtration chromatography have revealed that this protein is a single polypeptide and its relative molecular weight is 135 kDa. Immunoprecipitation and immunofluorescence microscopic analysis have indicated the presence of the above polypeptide in the nuclear fraction of heart cells. Studies on phosphorylation in vitro have revealed that this protein is a phosphoprotein. DNase I sensitivity and hybridization using a muscle specific gene probe have indicated the involvement of this protein in template associated changes in heart nuclei. Further the possibility of this protein being synthesized by heart cells indicates that this protein could traverse back and forth between heart cells and the extracellular fluid, suggesting an autocrine/paracrine role for this protein during the development of cardiac hypertrophy.

Animals↗