Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Enhancer RNAs”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 667 records · Page 37Linked to original sources
PubMed2001

Increased expression of the INK4a/ARF locus in polycythemia vera.

The retinoblastoma (Rb), cyclin-dependent kinase (CDK), and CDK inhibitor genes regulate cell generation, and deregulation can produce increased cell growth and tumorigenesis. Polycythemia vera (PV) is a clonal myeloproliferative disease where the mechanism producing increased hematopoiesis is still unknown. To investigate possible defects in cell-cycle regulation in PV, the expression of Rb and CDK inhibitor gene messenger RNAs (mRNAs) in highly purified human erythroid colony-forming cells (ECFCs) was screened using an RNase protection assay (RPA) and 11 gene probes. It was found that RNA representing exon 2 of p16(INK4a) and p14(ARF) was enhanced by 2.8- to 15.9-fold in 11 patients with PV. No increase of exon 2 mRNA was evident in the T cells of patients with PV, or in the ECFCs and T cells from patients with secondary polycythemia. p27 also had elevated mRNA expression in PV ECFCs, but to a lesser degree. Because the INK4a/ARF locus encodes 2 tumor suppressors, p16(INK4a) and p14(ARF) with the same exon 2 sequence, the increased mRNA fragment could represent either one. To clarify this, mRNA representing the unique first exons of INK4a and ARF were analyzed by semiquantitative reverse transcription-polymerase chain reaction. This demonstrated that mRNAs from the first exons of both genes were increased in erythroid and granulocyte-macrophage cells and Western blot analysis showed that the INK4a protein (p16(INK4a)) was increased in PV ECFCs. Sequencing revealed no mutations of INK4a or ARF in 10 patients with PV. p16(INK4a) is an important negative cell-cycle regulator, but in contrast with a wide range of malignancies where inactivation of the INK4a gene is one of the most common carcinogenetic events, in PV p16( INK4a) expression was dramatically increased without a significant change in ECFC cell cycle compared with normal ECFCs. It is quite likely that p16(INK4a) and p14(ARF) are not the pathogenetic cause of PV, but instead represent a cellular response to an abnormality of a downstream regulator of proliferation such as cyclin D, CDK4/CDK6, Rb, or E2F. Further work to delineate the function of these genes in PV is in progress. (Blood. 2001;97:3424-3432)

Aged↗
PubMed2003

Vascular endothelial growth factor-C and vascular endothelial growth factor-d messenger RNA expression in breast cancer: association with lymph node metastasis.

Lymph node metastasis is a major prognostic factor for patients with breast cancer. Vascular endothelial growth factors (VEGF)-C and VEGF-D are capable of stimulating lymphangiogenesis, and VEGF-C enhances lymphatic metastasis. The aim of the present study was to determine whether VEGF-C and VEGF-D messenger RNA (mRNA) expression is correlated with lymphatic invasion and lymph node metastasis in patients with breast cancer. Total RNAs were isolated from 33 surgical specimens of breast cancer tissue and 7 samples of normal breast tissue. VEGF-C and VEGF-D mRNA expression was measured by quantitative reverse transcription-polymerase chain reaction analysis. There was no correlation between VEGF-C mRNA expression and lymphatic invasion or lymph node metastasis. However, VEGF-D mRNA expression was decreased in cancer tissue, and it was inversely correlated with lymphatic invasion and the number of metastatic lymph nodes. An increased VEGF-C/VEGF-D ratio was also correlated with lymph node metastasis and the number of metastatic lymph nodes. Our results suggest that a decrease in VEGF-D mRNA or an increase in the VEGF-C/VEGF-D ratio may have an association with tumorigenesis and/or lymph node metastasis in breast cancer.

Adult↗
PubMed2004

A novel oncoprotein RNF43 functions in an autocrine manner in colorectal cancer.

We previously analyzed expression profiles of 20 colorectal tumors by means of genome-wide cDNA microarray. Among the genes that were commonly up-regulated in the CRCs, we further characterized biological importance of a novel human gene termed RNF43 (RING finger protein 43) in colorectal carcinogenesis. Multiple-tissue northern blot analysis revealed undetectable expression of RNF43 in normal adult tissues examined and low levels of expression in fetal kidney and lung. Its exogenous expression conferred a growth-promoting effect in COS7 and NIH3T3 cells, and suppression of its expression by specific short interfering RNAs retarded the growth of colon cancer cells. Interestingly, RNF43 protein was shown to be a secreted protein, and addition of the conditioned media of the RNF43-transfected cells into culture media of NIH3T3 cells revealed a significant enhancement of cell growth. These data suggest that RNF43 may exert its growth promoting effect in an antocrine manner, and that it may be a novel diagnostic marker for colorectal cancer.

Blotting, Northern↗
PubMed1991

Translational efficiency and competitive ability of mRNAs with 5'-untranslated alpha beta-leader of potato virus X RNA.

The 5'-untranslated leader sequence of potato virus X (PVX) RNA (63 nucleotides apart from cap-structure) consists of two sub-sequences referred to as alpha-sequence (41 nucleotides with no G) and beta-sequence (42 nucleotides upstream from the first AUG). Computer-based folding predictions suggest that the 5'-proximal region of alpha beta-leader is unstructured. The second structural feature of alpha beta-leader is the presence of the sequences apparently complementary to the 3'-terminal region of 18S rRNA. The alpha beta-leader has been shown to strongly enhance the translation of the contiguous foreign gene (NPT1) transcripts in cell-free translation systems from rabbit reticulocytes (RRL), wheat germ (WG) and Krebs-2 ascite cell extract (KA). In competitive translation PVX, RNA strongly inhibited tobacco mosaic virus (TMV) RNA, in RRL and WG systems. No competition occurred between PVX and TMV RNAs in KA system. There was no correlation between the translational efficiency and competitive ability of PVX RNA in different cell-free translation systems. The competitive ability did not solely depend on the presence of alpha beta-leader in mRNA. We present evidence to suggest that alpha beta-leader together with about 150 bases of the coding sequence is responsible for the translation competitive ability of PVX RNA.

Base Sequence↗
PubMed2002

Modulation of homo- and heterodimerization of Harvey sarcoma virus RNA by GACG tetraloops and point mutations in palindromic sequences.

Retroviruses harbour a diploid genome of two plus-strand RNAs linked non-covalently at the dimer linkage structure. Co-packaging of two parental RNAs is a prerequisite for recombination in retroviruses, but formation of heterodimers has not been demonstrated directly in vivo. Here, we explore elements in Harvey sarcoma virus (HaSV) RNA involved in homodimerization and heterodimerization with RNA of Moloney (Mo) and Akv murine leukemia viruses (MLV). By an in vitro assay, we found that HaSV dimerization specificity could be modulated by mutations in a decanucleotide palindrome (Pal) probably folded into a kissing-loop. Autocomplementary and non-autocomplementary sequences introduced into the putative loop directed the specificity towards formation of homodimers and heterodimers, respectively. Two stem-loop (SL) structures, both exposing a GACG tetraloop, enhanced the formation of stable HaSV dimers.A similar decanucleotide palindrome has been implicated in homodimerization of MLVs. Heterodimers between HaSV RNA and Mo- or Akv MLV were unstable, but could be stabilized by introduction of two point mutations in the putative HaSV kissing-loop, creating exact complementarity with Mo/Akv MLV palindromes. Moreover, such changes increased the HaSV RNA affinity for the two MLV RNAs. Similar to HaSV RNA homodimers, formation of heterodimers with Mo- or Akv MLV RNAs was induced by the presence of GACG loops. On the basis of these results, we propose that palindromic sequences act as variable determinants of specificity and GACG tetraloops as conserved determinants in the formation of homodimers and heterodimers of gamma-retrovirus retroviral RNAs in vivo. The complementarity of loop sequences in the packaging signal upstream of the GACG tetraloops might therefore determine homo- and heterodimerization specificity and recombination activity of these viruses.

Base Pairing↗
PubMed2002

Transvection effects in Drosophila.

An unusual feature of the Diptera is that homologous chromosomes are intimately synapsed in somatic cells. At a number of loci in Drosophila, this pairing can significantly influence gene expression. Such influences were first detected within the bithorax complex (BX-C) by E.B. Lewis, who coined the term transvection to describe them. Most cases of transvection involve the action of enhancers in trans. At several loci deletion of the promoter greatly increases this action in trans, suggesting that enhancers are normally tethered in cis by the promoter region. Transvection can also occur by the action of silencers in trans or by the spreading of position effect variegation from rearrangements having heterochromatic breakpoints to paired unrearranged chromosomes. Although not demonstrated, other cases of transvection may involve the production of joint RNAs by trans-splicing. Several cases of transvection require Zeste, a DNA-binding protein that is thought to facilitate homolog interactions by self-aggregation. Genes showing transvection can differ greatly in their response to pairing disruption. In several cases, transvection appears to require intimate synapsis of homologs. However, in at least one case (transvection of the iab-5,6,7 region of the BX-C), transvection is independent of synapsis within and surrounding the interacting gene. The latter example suggests that transvection could well occur in organisms that lack somatic pairing. In support of this, transvection-like phenomena have been described in a number of different organisms, including plants, fungi, and mammals.

Animals↗
PubMed2000

Functions of the 126- and 183-kDa proteins of tobacco mosaic virus.

Tobacco mosaic virus produces two proteins that contain domains similar to the methyltransferase (MT) and helicase (HEL)-like domains of the replicase-associated proteins of other RNA viruses. The more abundant 126-kDa protein contains only the MT and HEL-like domains, whereas the 183-kDa readthrough protein additionally contains the polymerase domain. We examined the functions of these proteins by constructing a bipartite system to express the 126- and 183-kDa proteins from separate RNAs. Mutants expressing the 183-kDa protein recognized promoters for negative- and positive-stranded RNA synthesis, transcribed subgenomic mRNAs, capped RNAs, synthesized proteins, moved cell to cell within the plant, and replicated defective RNAs (dRNAs). The principal function of the 126-kDa protein was to increase the rate of replication approximately tenfold. The 126-kDa protein appeared to function primarily in cis, and production of the 126-kDa protein in trans did not enhance replication of the helper virus. dRNAs producing a functional 126-kDa protein were replicated efficiently by helper viruses that produced only the 183-kDa protein but not by wild-type virus, suggesting that efficient replication required the 183-kDa protein to form a heterodimer with the 126-kDa protein already bound to the target dRNA.

Frameshift Mutation↗
PubMed2004

Regulation of nuclear receptor activity by a pseudouridine synthase through posttranscriptional modification of steroid receptor RNA activator.

Nuclear receptors (NRs) induce transcription through association with coactivator complexes. We identified a pseudouridine synthase (PUS), mPus1p, as a coactivator for retinoic acid receptor (mRAR)gamma and other NR-dependent transactivation. mPus1p is a member of the truA subfamily of PUSs, a class of enzymes that isomerize uridine to pseudouridine in noncoding RNAs, such as tRNA, to ensure proper folding and function. mPus1p binds the first zinc finger of mRARgamma and also associates with other NRs. Interestingly, mPus1p pseudouridylates coactivator Steroid Receptor RNA Activator (SRA), and when coexpressed, mPus1p and SRA cooperatively enhance mRARgamma-mediated transcription. mPus1p, mRARgamma, and SRA exist in a retinoid-independent, promoter bound complex in the nucleus although mPus1p is also expressed in the nucleolus, where it likely modifies tRNA. Finally, we show that mPus1p-coactivator function required SRA, mPus1p-associated mRARgamma binding, and PUS activities. mPus1p-dependent pseudouridylation of SRA represents an additional type of posttranscriptional modification of a NR-coactivator complex that is important for NR signaling.

Animals↗
PubMed2004

The syndecan-1 ectodomain regulates alphavbeta3 integrin activity in human mammary carcinoma cells.

The alpha(v)beta(3) integrin participates in cell morphogenesis, growth factor signaling, and cell survival. Activation of the integrin is central to these processes and is influenced by specific ECM components, which engage both integrins and syndecans. This paper demonstrates that the alpha(v)beta(3) integrin and syndecan-1 (S1) are functionally coupled. The integrin is dependent on the syndecan to become activated and to mediate signals required for MDA-MB-231 and MDA-MB-435 human mammary carcinoma cell spreading on vitronectin or S1-specific antibody. Coupling of the syndecan to alpha(v)beta(3) requires the S1 ectodomain (ED), as ectopic expression of glycosylphosphatidylinositol-linked S1ED enhances alpha(v)beta(3) recognition of vitronectin; and treatments that target this domain, including competition with recombinant S1ED protein or anti-S1ED antibodies, mutation of the S1ED, or down-regulation of S1 expression by small-interfering RNAs, disrupt alpha(v)beta(3)-dependent cell spreading and migration. Thus, S1 is likely to be a critical regulator of many cellular behaviors that depend on activated alpha(v)beta(3) integrins.

Breast Neoplasms↗
PubMed2004

tRNASer(CGA) differentially regulates expression of wild-type and codon-modified papillomavirus L1 genes.

Exogenous transfer RNAs (tRNAs) favor translation of bovine papillomavirus 1 wild-type (wt) L1 mRNA in in vitro translation systems (Zhou et al. 1999, J. Virol., 73, 4972-4982). We, therefore, investigated whether papillomavirus (PV) wt L1 protein expression could be enhanced in eukaryotic cells following exogenous tRNA supplementation. Both Chinese hamster ovary (CHO) and Cos1 cells, transfected with PV1 wt L1 genes, effectively transcribed the genes but did not translate them. However, L1 protein translation was demonstrated following co-transfection with the L1 gene and a gene expressing tRNA(Ser)(CGA). Cell lines, stably transfected with a bovine papillomavirus 1 (BPV1) wt L1 expression construct, produced L1 protein after the transfection of the tRNA(Ser)(CGA) gene, but not following the transfection with basal vectors, suggesting that tRNA(Ser)(CGA) gene enhanced wt L1 translation as a result of endogenous tRNA alterations and phosphorylation of translation initiation factors elF4E and elF2alpha in the tRNA(Ser)(CGA) transfected L1 cell lines. The tRNA(Ser)(CGA) gene expression significantly reduced translation of L1 proteins expressed from codon-modified (HB) PV L1 genes utilizing mammalian preferred codons, but had variable effects on translation of green fluorescent proteins (GFPs) expressed from six serine GFP variants. The changes of tRNA pools appear to match the codon composition of PV wt and HB L1 genes and serine GFP variants to regulate translation of their mRNAs. These findings demonstrate for the first time in eukaryotic cells that translation of the target genes can be differentially influenced by the provision of a single tRNA expression construct.

Animals↗
PubMed2002

A Y639F/H784A T7 RNA polymerase double mutant displays superior properties for synthesizing RNAs with non-canonical NTPs.

A T7 RNA polymerase in which Tyr639 is mutated to Phe readily utilizes 2'-deoxy, 2'-NH2 and 2'-F NTPs as substrates and has been widely used to synthesize modified RNAs for a variety of applications. This mutant does not readily utilize NTPs with bulkier 2'-substituents, nor does it facilitate incorporation of NTPs with modifications at other positions. Introduction of a second mutation (H784A) into the Y639F background markedly enhances utilization of NTPs with bulky 2'-substituents (2'-OMe and 2'-N3), and may also enhance use of NTPs with modifications at other than the 2'-position. The Y639F/H784A double mutant may therefore be exceptionally useful for incorporation of a variety of non-canonical NMPs into RNA.

Amino Acid Substitution↗
PubMed1987

Transformation of differentiated rat hepatocytes with adenovirus and adenovirus DNA.

Primary cultures of hepatocytes isolated by collagenase perfusion of adult rats were transformed by infection with adenovirus type 5 or transfection with adenovirus DNA. Total virion DNA or recombinant plasmid DNA containing the adenovirus E1A and E1B genes transformed hepatocytes at comparable frequencies. No foci of replicating hepatocytes were detected after transfection with a plasmid containing the E1A gene alone. The frequency of transformation by the adenovirus E1A and E1B genes was dependent on the composition of the culture medium. Transformation occurred at a low frequency when the transfected hepatocytes were maintained in a chemically defined medium (CDM), but the frequency was enhanced 8- to 10-fold when the cells were maintained in (i) serum-supplemented medium or (ii) CDM supplemented with epidermal growth factor. Cell lines derived from the adenovirus-transformed colonies of hepatocytes expressed adenovirus E1A and E1B RNAs. When hepatocytes were maintained in CDM supplemented with dimethyl sulfoxide and transfected with plasmids containing the E1A and E1B genes, it was possible to derive cell lines that retained the ability to express several liver-specific genes, including albumin, transferrin, hemopexin, and the third component of complement. The amount of albumin secreted per cell varied from 1 to 5 pg per cell per 24 h, and in one cell line it was below detectable levels by passage 9. Adenovirus-transformed hepatocytes were not tumorigenic when inoculated subcutaneously into neonatal syngeneic rats. We conclude that the adenovirus E1A and E1B genes are capable of transforming adult rat hepatocytes, a differentiated epithelial cell type.

Adenoviruses, Human↗
PubMed1994

Effect of 5-fluoro- and 5-bromouracil substitution on the translation of human thymidylate synthase mRNA.

The synthesis of thymidylate synthase (TS) from 5-fluorouracil (FUra)- and 5-bromouracil (BrUra)-substituted mRNAs was examined to investigate the effect of incorporation of uracil (Ura) analogs on translation. Human TS cDNA was transcribed in the presence of Ura-, FUra-, or BrUTP to obtain 100% substituted mRNA. The mRNAs were translated in a rabbit reticulocyte lysate system. The TS protein that was formed from each of the templates reacted identically with TS antibody in Western blots. Time courses of TS formation revealed a characteristic peak which occurred at 45 min for the Ura- and FUra-RNAs and at 2 h for the BrUra-RNA. Substitution of Ura with FUra did not alter the rate of translation, while substitution of BrU for Ura decreased the rate of translation. Substitution of Ura with FUra or BrUra enhanced the stability of the mRNAs in the rabbit reticulocyte lysate by 3- and 10-fold, respectively. Incorporation of BrUra influenced the binding and catalysis on the ribosome, resulting in a 3.5-fold greater rate of activation (Kact) and 6-fold lower Vmax than the equivalent values for the Ura- and FUra-substituted mRNAs. Nondenaturing gel electrophoresis revealed that different conformations exist among the mRNAs. These data show that translation can be influenced by the incorporation of fraudulent bases into mRNA and those bases that stabilize RNA secondary structure will have the greatest inhibitory effect on translation.

Base Sequence↗
PubMed2003

Small interfering RNA (siRNA) targeting VEGF effectively inhibits ocular neovascularization in a mouse model.

PURPOSE: RNA interference mediated by small interfering RNAs (siRNAs) is a powerful technology allowing the silencing of mamalian genes with great specificity and potency. The purpose of this study was to demonstrate the feasibility of RNA interference mediated by siRNA in retinal cells in vitro and in the murine retina in vivo. METHODS: siRNAs specific for enhanced green fluorescent protein (EGFP) and murine and human vascular endothelial growth factor (VEGF) were designed. In vitro studies in human cell lines entailed modulation of endogenous VEGF levels through chemically induced hypoxia. Effects of siRNA treatment on these levels were measured by ELISA. In vivo studies evaluating effects of siRNA on levels of EGFP and VEGF were performed by co-injecting recombinant viruses carrying EGFP or hVEGF cDNAs along with the appropriate siRNAs subretinally in mice. Additional studies aimed at blocking production of endogenous mVEGF were performed using laser-induced choroidal neovascularization (CNV) in mice. Effects of in vivo treatments were evaluated ophthalmoscopically. Retinal/choroidal flat mounts were evaluated after perfusion with dextran-fluorescein. Alternatively, retinas were evaluated in histological sections or VEGF levels were measured in intact eyes using ELISA. RESULTS: Successful delivery of siRNA to the subretinal space was confirmed by observing significantly reduced levels of EGFP in eyes treated with Ad.CMV.EGFP plus EGFP-directed siRNA. siRNAs directed against hVEGF effectively and specifically inhibit hypoxia-induced VEGF levels in human cell lines and after adenoviral induced hVEGF transgene expression in vivo. In addition, subretinal delivery of siRNA directed against murine Vegf significantly inhibited CNV after laser photocoagulation. CONCLUSIONS: Delivery of siRNA can be used in vitro and in vivo to target specific RNAs and to reduce the levels of the specific protein product in the targeted cells. This work suggests that RNA interference has potential for application to studies of retinal biology and for the treatment of a variety of retinal diseases, including those involving abnormal blood vessel growth.

Adenoviruses, Human↗
PubMed1994

A B-type cyclin negatively regulates conjugation via interacting with cell cycle 'start' genes in fission yeast.

In the fission yeast Schizosaccharomyces pombe, the cdc10+/SWI family members constitute the cell cycle 'start' genes. res1+ and res2+ are the newly identified members of this family and encode putative association partners of the Cdc10 protein. The Pat1 kinase plays a pivotal role in switching between vegetative growth and sexual development, and its inactivation in haploid cells induces unconditional growth arrest and subsequent meiosis. We have identified as an extragenic suppressor of a temperature sensitive pat1-114 mutant, a new B-type cyclin that negatively regulates conjugation by interacting with these 'start' genes. This cyclin, named Cyc17, is highly homologous with Cdc13, but has no detectable activity as a mitotic cyclin. Deletion of cyc17+ markedly enhances conjugation, despite the presence of nitrogen source, and accelerates growth arrest in G1 upon nitrogen starvation. Conversely, overexpression of the cyc17+ gene strongly inhibits conjugation. The cyc17+ gene is transcribed into 3.2 kb poly(A)+ and 3.0 kb poly(A)- RNAs. Only the poly(A)+ species is expressed during vegetative growth and periodically with a peak in the G1 and S phases of the cell cycle. On the other hand, the poly(A)- transcript is highly induced during conjugation. This induction is lost in res2- cells, whereas the poly(A)+ transcript is significantly reduced in res1- cells. However, the mating inhibition as well as the ability to rescue the pat1 mutation by overexpression of res1+ and res2+ are totally abolished in cyc17- cells. Thus, in S.pombe, a B-type cyclin, regulated by the newly identified cell cycle 'start' genes, plays a crucial role in the control of sexual development.

Amino Acid Sequence↗
PubMed2001

Down-regulation of translation driven by hepatitis C virus internal ribosomal entry site by the 3' untranslated region of RNA.

The genome of hepatitis C virus (HCV) is a single-stranded RNA of positive polarity that has a poly(U/C) tract followed by a highly conserved 98-nt sequence, termed the X region, in the 3' untranslated region (UTR). To investigate the effect of the 3'UTR on the HCV translation that depends on the internal ribosomal entry site (IRES), we prepared a deletion HCV RNA, MA delta, that lacked the RNA region from nt 1286 to 8785. A series of MA delta RNAs that differ in the primary structure of their 3'UTR, were generated and examined for their translation efficiencies in reticulocyte lysates. Deletion of the poly(U/C) tract and/or stem-loop structure (SL) 3 region of 3'X resulted in enhancement of the translation efficiency. Translation of MA delta RNA was inhibited by the addition of recombinant polypyrimidine tract-binding protein (PTB). A similar inhibition by PTB, however, was observed when an RNA lacking the poly(U/C) tract or SL3 region was used. The inhibitory effect by PTB was not obvious for MA delta (1041) RNA composed of nt 1 to 1041 but MA delta (8928) RNA composed of nt 1 to 1285 and nt 8786 to 8928. These results suggest that the observed down-regulation of HCV translation by the 3'UTR is mediated by some host factor(s) other than PTB, and that a PTB site for inhibition resides in the coding sequence of nt 1042 to 8928 of MA delta RNA.

3' Untranslated Regions↗
PubMed1991

Regulation of extracellular matrix production by chemically synthesized subfragments of type I collagen carboxy propeptide.

The complete COOH-propeptide of human alpha 1(I) procollagen was chemically synthesized as a series of overlapping subfragments which were then tested for their effect on extracellular matrix protein production by subconfluent human lung fibroblasts (HFL-1). One peptide (R11; residues 197-241) stimulated production of both collagen and fibronectin by 6-8-fold while a second peptide with a partial overlap with R11 (R9; residues 182-216) enhanced collagen accumulation. The peptide R12 (residues 197-216), which has a sequence common to both R9 and R11, also stimulated collagen production, suggesting that this 20-residues peptide alone contains the required structure for activity. The other synthetic peptides, R1-R13, were inactive in their ability to alter collagen or fibronectin production. Consistent with previously published data, the COOH-terminal peptide, R14, inhibited extracellular matrix production [Aycock, R.A., Raghow, R., Stricklin, G.P., Seyer, J.M., & Kang, A.H. (1986) J. Biol. Chem. 261, 14355-14360]. Both R9 and R11 preferentially stimulated production of collagen types I and III and fibronectin in dose-dependent manner. Elevated collagen and fibronectin production was evident at 4-h posttreatment, and maximal enhancement was seen at 8 h after exposure to peptides. Interestingly, subconfluent cultures of HFL-1 fibroblasts responded vigorously to the stimulatory action of R9 and R11 while confluent cells failed to show any response. Steady-state levels of messenger RNAs encoding type I procollagen and fibronectin were not measurably altered by treatment with R9 or R11, suggesting that the regulation of procollagens and fibronectin by these peptides involves posttranscriptional mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Protein kinase C isozymes epsilon and alpha in murine erythroleukemia cells.

Protein kinase C (PKC) has a role in signal transduction during hexamethylene bisacetamide (HMBA)-induced differentiation of murine erythroleukemia cells (MELC). Separation of MELC PKC isozymes by hydroxylapatite chromatography yields a major peak (III) and a minor peak (II) of PKC activity, previously reported to contain the PKC alpha and beta isozymes, respectively. In the present study, we confirm that peak III activity is PKC alpha but show that peak II contains PKC epsilon and little or no PKC beta. Immunoblot analysis with isozyme-specific anti-alpha and anti-epsilon PKC antibodies detected PKC alpha in peak III and PKC epsilon in peak II. Peak III activity was markedly enhanced (up to 20-fold) by phosphatidylserine, diolein, and Ca2+, whereas addition of these cofactors to the reaction mixture stimulated peak II activity only 2- to 4-fold. RNase protection analysis of MELC RNA showed that PKC alpha and PKC epsilon RNAs were in a ratio of approximately 2:1, but PKC beta RNA was barely detectable. Taken together, these data indicate that MELC contain PKC alpha and PKC epsilon but little or no PKC beta.

Animals↗