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mRNA Content (mrna + content)
Selected AbstractsMineralocorticoid Receptor Is Overexpressed in Cardiomyocytes of Patients With Congestive Heart FailureCONGESTIVE HEART FAILURE, Issue 1 2005Masahiro Yoshida MD Mineralocorticoid receptors (MRs) have been identified in the human cardiovascular tissues. We determined MR expression in the failing heart to clarify the mechanism of action of aldosterone antagonist in the treatment of congestive heart failure. MR protein and MR mRNA content were detected by immunohistochemical staining and in situ hybridization in the cardiac tissues. Immunohistochemical staining of the receptor, as well as in situ hybridization of MR mRNA, was dense in cardiomyocytes of the failing left ventricle as compared with the controls. The staining ratio of the cytoplasm to the interstitium showed that MRs were located mainly in the cytoplasm. The cytoplasm to the interstitium in the failing left ventricle was 1.53±0.13, which was significantly higher than that of the controls 1.25±0.19 (p<0.05). These findings suggest that the efficacy of aldosterone antagonists in treating congestive heart failure may be in part through blocking the MRs, which are upregulated in the failing heart. [source] Increased fat oxidation and regulation of metabolic genes with ultraendurance exerciseACTA PHYSIOLOGICA, Issue 1 2007J. W. Helge Abstract Aim:, Regular endurance exercise stimulates muscle metabolic capacity, but effects of very prolonged endurance exercise are largely unknown. This study examined muscle substrate availability and utilization during prolonged endurance exercise, and associated metabolic genes. Methods:, Data were obtained from 11 competitors of a 4- to 5-day, almost continuous ultraendurance race (seven males, four females; age: 36 ± 11 years; cycling o2peak: males 57.4 ± 5.9, females 48.1 ± 4.0 mL kg,1 min,1). Before and after the race muscle biopsies were obtained from vastus lateralis, respiratory gases were sampled during cycling at 25 and 50% peak aerobic power output, venous samples were obtained, and fat mass was estimated by bioimpedance under standardized conditions. Results:, After the race fat mass was decreased by 1.6 ± 0.4 kg (11%; P < 0.01). Respiratory exchange ratio at the 25 and 50% workloads decreased (P < 0.01) from 0.83 ± 0.06 and 0.93 ± 0.03 before, to 0.71 ± 0.01 and 0.85 ± 0.02, respectively, after the race. Plasma fatty acids were 3.5 times higher (from 298 ± 74 to 1407 ± 118 ,mol L,1; P < 0.01). Muscle glycogen content fell 50% (from 554 ± 28 to 270 ± 25 nmol kg,1 d.w.; n = 7, P < 0.01), whereas the decline in muscle triacylglycerol (from 32 ± 5 to 22 ± 3 mmol kg,1 d.w.; P = 0.14) was not statistically significant. After the race, muscle mRNA content of lipoprotein lipase and glycogen synthase increased (P < 0.05) 3.9- and 1.7-fold, respectively, while forkhead homolog in rhabdomyosarcoma, pyruvate dehydrogenase kinase 4 and vascular endothelial growth factor mRNA tended (P < 0.10) to be higher, whereas muscle peroxisome proliferator-activated receptor , co-activator-1, mRNA tended to be lower (P = 0.06). Conclusion:, Very prolonged exercise markedly increases plasma fatty acid availability and fat utilization during exercise. Exercise-induced regulation of genes encoding proteins involved in fatty acid recruitment and oxidation may contribute to these changes. [source] Effects of rapamycin on accumulation of , -, , - and , -globin mRNAs in erythroid precursor cells from , -thalassaemia patientsEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 5 2006Eitan Fibach Abstract:, We studied the effects of rapamycin on cultures of erythroid progenitors derived from the peripheral blood of 10 , -thalassaemia patients differing widely with respect to their potential to produce foetal haemoglobin (HbF). For this, we employed the two-phase liquid culture procedure for growing erythroid progenitors, high performance liquid chromatography for analysis of HbF production and reverse transcription polymerase chain reaction for quantification of the accumulation of globin mRNAs. The results demonstrated that rapamycin induced an increase of HbF in cultures from all the , -thalassaemia patients studied and an increase of their overall Hb content/cell. The inducing effect of rapamycin was restricted to , -globin mRNA accumulation, being only minor for , -globin and none for , -globin mRNAs. The ability of rapamycin to preferentially increase , -globin mRNA content and production of HbF in erythroid precursor cells from , -thalassaemia patients is of great importance as this agent (also known as sirolimus or rapamune) is already in clinical use as an anti-rejection agent following kidney transplantation. These data suggest that rapamycin warrants further evaluation as a potential therapeutic drug in , -thalassaemia and sickle cell anaemia. [source] Neuronal nitric oxide synthase (nNOS) mRNA is down-regulated, and constitutive NOS enzymatic activity decreased, in thoracic dorsal root ganglia and spinal cord of the rat by a substance P N-terminal metaboliteEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2001Katalin J. Kovacs Abstract Nitric oxide (NO) in the spinal cord plays a role in sensory and autonomic activity. Pain induced by acetic acid in the abdominal stretch (writhing) assay and hyperalgesia associated with chronic pain are highly sensitive to NO synthase (NOS) inhibitors. Because substance P (SP) is released and up-regulated in some models of chronic pain, we hypothesized that an accumulation of SP metabolites may influence NOS expression and activity. To test this hypothesis, we examined the effect of intrathecally (i.t.) injected substance P (1-7) [SP(1-7)], the major metabolite of SP in the rat, on neuronal NOS (nNOS) mRNA in the thoracic and lumbar spinal cord, dorsal root ganglia (DRG) and on the corresponding constitutive NOS (cNOS) enzyme activity. Detected using quantitative RT-PCR, nNOS mRNA content in the thoracic spinal cord was decreased 6 h after injection of 5 µmol of SP(1-7) and returned to control 2 days later. In thoracic DRG, nNOS mRNA was reduced 48 h after SP(1-7). The cNOS enzymatic activity in thoracic spinal tissue was gradually decreased to a minimum at 72 h. Down-regulation of NOS by SP(1-7) in the thoracic area appears to be highly associated with capsaicin-sensitive primary afferent neurons. No similar changes in either parameter were measured in the lumbar area after SP(1-7). These data suggest that N-terminal SP fragments, which are known to cause long-term antinociception in the writhing assay, may do so by their ability to down-regulate NO synthesis along nociceptive pathways. [source] The role of steroid hormones in the regulation of vasopressin and oxytocin release and mRNA expression in hypothalamo neurohypophysial explants from the ratEXPERIMENTAL PHYSIOLOGY, Issue 2000Celia D. Sladek Vasopressin and oxytocin release from the neural lobe, and the vasopressin and oxytocin mRNA contents of the supraoptic and paraventricular nuclei are increased by hypertonicity of the extracellular fluid. The factors regulating these parameters can be conveniently studied in perifused explants of the hypothalamo-neurohypophysial system that include the supraoptic nucleus (but not the paraventricular nucleus) with its axonal projections to the neural lobe. Vasopressin and oxytocin release and the mRNA content of these explants respond appropriately to increases in the osmolality of the perifusate. This requires synaptic input from the region of the organum vasculosum of the lamina terminalis. Glutamate is a likely candidate for transmitting osmotic information from the organum vasculosum of the lamina terminalis to the magnocellular neurones, because agonists for excitatory amino acid receptors stimulate vasopressin and oxytocin release, and because increased vasopressin release and mRNA content induced in hypothalamo-neurohypophysial explants by a ramp increase in osmolality are blocked by antagonists of both NMDA (N -methyl-D-aspartate) and non-NMDA glutamate receptors. Osmotically stimulated vasopressin release is also blocked by testosterone, dihydrotestosterone, oestradiol and corticosterone. Both oestrogen and dihydrotestosterone block NMDA stimulation of vasopressin release, and in preliminary studies oestradiol blocked AMPA stimulation of vasopressin release. Thus, steroid inhibition of osmotically stimulated vasopressin secretion may reflect inhibition of mechanisms mediated by excitatory amino acids. Recent studies have demonstrated numerous mechanisms by which steroid hormones may impact upon neuronal function. Therefore, additional work is warranted to understand these effects of the steroid hormones on vasopressin and oxytocin secretion and to elucidate the potential contribution of these mechanisms to regulation of hormone release in vivo. [source] [Na+]i -induced c-Fos expression is not mediated by activation of the 5,-promoter containing known transcriptional elementsFEBS JOURNAL, Issue 14 2007Mounsif Haloui In vascular smooth muscle cells and several other cell types, inhibition of Na+/K+ -ATPase leads to the expression of early response genes, including c-Fos. We designed this study to examine whether or not a putative Na+i/K+i -sensitive element is located within the c-Fos 5,-UTR from ,,650 to +,103 containing all known response elements activated by ,classic' stimuli, such as growth factors and Ca2+i -raising compounds. In HeLa cells, the highest increment of c-Fos mRNA content was noted after 6 h of Na+/K+ -ATPase inhibition with ouabain that was abolished by actinomycin D, an inhibitor of RNA synthesis. c-Fos protein accumulation in ouabain-treated cells correlated with a gain of Na+i and loss of K+i. Augmented c-Fos expression was also observed under inhibition of Na+/K+ -ATPase in K+ -free medium and in the presence of the Na+ ionophore monensin. The effect of ouabain on c-Fos expression was sharply attenuated under dissipation of the transmembrane Na+ gradient, but was preserved in the presence of Ca2+ chelators and the extracellular regulated kinase inhibitor PD98059, thus indicating an Na+i -mediated, Ca2+i - and extracellular regulated kinase-independent mechanism of gene expression. In contrast to massive c-Fos expression, we failed to detect any effect of ouabain on accumulation of luciferase driven by the c-Fos 5,-UTR. Negative results were also obtained in ouabain-treated vascular smooth muscle cells and C11 Madin,Darby canine kidney cells possessing augmented c-Fos expression. Our results reveal that Na+i -induced c-Fos expression is not mediated by the 5,-UTR containing transcriptional elements activated by growth factors and other ,classic stimuli'. [source] ABCG2 overexpression in colon cancer cells resistant to SN38 and in irinotecan-treated metastasesINTERNATIONAL JOURNAL OF CANCER, Issue 6 2004Laurent Candeil Abstract Overcoming drug resistance has become an important issue in cancer chemotherapy. Among all known mechanisms that confer resistance, active efflux of chemotherapeutic agents by proteins from the ATP-binding cassette family has been extensively reported. The aim of the present study was to determine the involvement of ABCG2 in resistance to SN38 (the active metabolite of irinotecan) in colorectal cancer. By progressive exposure to increasing concentrations of SN38, we isolated 2 resistant clones from the human colon carcinoma cell line HCT116. These clones were 6- and 53-fold more resistant to SN38 than the HCT116-derived sensitive clone. Topoisomerase I expression was unchanged in our resistant variants. The highest resistance level correlated with an ABCG2 amplification. This overexpression was associated with a marked decrease in the intracellular accumulation of SN38. The inhibition of ABCG2 function by Ko143 demonstrated that enhanced drug efflux from resistant cells was mediated by the activity of ABCG2 protein and confirmed that ABCG2 is directly involved in acquired resistance to SN38. Furthermore, we show, for the first time in clinical samples, that the ABCG2 mRNA content in hepatic metastases is higher after an irinotecan-based chemotherapy than in irinotecan-naive metastases. In conclusion, this study supports the potential involvement of ABCG2 in the development of irinotecan resistance in vivo. © 2004 Wiley-Liss, Inc. [source] Characterization of the porcine Kisspeptins receptor gene and evaluation as candidate for timing of puberty in sowsJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 4 2008S. Li Summary Kisspeptins receptor (KISS1R), also called GPR54, is a key regulator of puberty in many species. KISS1R and its genetics in pigs remain unexplored. The objective of this study was to characterize the porcine KISS1R gene and evaluate the association of KISS1R mutations with age at puberty in sows. KISS1R was assigned to pig chromosome 2q21-24 by radiation hybrid mapping. It has a 1438 bp full-length cDNA and spans 3349 bp genomic sequence consisting of five exons and four introns. Semi-quantitative RT-PCR showed that KISS1R transcripts was particularly abundant in the adrenal, prostate, testis, thymus, pituary and hypothalamus. KISS1R mRNA content in the hypothalamus was determined by real-time quantitative RT-PCR, and it fluctuated during the oestrous cycle with the highest level in the luteal phase. Anoestrus sows had markedly lower hypothalamic KISS1R mRNA content than cyclic animals. Seven KISS1R SNPs were identified in the founder animals of a White Duroc × Erhualian intercross. One missense mutation (T/C245) showed quite different allele distribution in Chinese and Western breeds. All F0, F1 animals and 367 detailed phenotyped cyclic F2 sows in the White Duroc × Erhualian intercross were genotyped for three KISS1R polymorphisms. No significant association of KISS1R haplotypes and haplotype pairs with age at puberty was observed in the resource population, indicating that mutations in KISS1R are not responsible for divergent age at puberty in White Duroc and Erhualian pigs. [source] Roles of Corticotropin-Releasing Factor, Neuropeptide Y and Corticosterone in the Regulation of Food Intake In Xenopus laevisJOURNAL OF NEUROENDOCRINOLOGY, Issue 3 2004E. J. Crespi Abstract In mammals, hypothalamic control of food intake involves counterregulation of appetite by anorexigenic peptides such as corticotropin-releasing factor (CRF), and orexigenic peptides such as neuropeptide Y (NPY). Glucocorticoids also stimulate food intake by inhibiting CRF while facilitating NPY actions. To gain a better understanding of the diversity and evolution of neuroendocrine feeding controls in vertebrates, we analysed the effects of CRF, NPY and glucocorticoids on food intake in juvenile Xenopus laevis. We also analysed brain CRF and NPY mRNA content and plasma corticosterone concentrations in relation to nutritional state. Intracerebroventricular (i.c.v.) injection of ovine CRF suppressed food intake while CRF receptor antagonist ,helical CRF(9,41) significantly increased food intake relative to uninjected and placebo controls. By contrast, i.c.v. injection of frog NPY and short-term corticosterone treatment increased food intake. Semi-quantitative reverse transcription-polymerase chain reaction analyses showed that CRF and NPY mRNA fluctuated with food intake in the brain region containing the mid-posterior hypothalamus, pretectum, and optic tectum: CRF mRNA decreased 6 h after a meal and remained low through 31 days of food deprivation; NPY mRNA content also decreased 6 h after a meal, but increased to prefeeding levels by 24 h. Plasma corticosterone concentration increased 6 h after a meal, returned to prefeeding levels by 24 h, and did not change with prolonged food deprivation. This postprandial increase in plasma corticosterone may be related to the subsequent increase in plasma glucose and body water content that occurs 24 h postfeeding. Overall, our data support the conclusion that, similar to other vertebrates, CRF is anorexigenic while NPY is orexigenic in X. laevis, and CRF secretion modulates food intake in the absence of stress by exerting an inhibitory tone on appetite. Furthermore, the stress axis is activated in response to food intake, but in contrast to mammals and birds is not activated during periods of food deprivation. [source] Synaptic mRNAs are modulated by learningJOURNAL OF NEUROSCIENCE RESEARCH, Issue 9 2009Eugenia Ferrara Abstract We have recently demonstrated that brain plastic events significantly modify synaptic protein synthesis measured by the incorporation of [35S]methionine in brain synaptosomal proteins. Notably, in rats learning a two-way active avoidance task, the local synthesis of two synaptic proteins was selectively enhanced. Because this effect may be attributed to transcriptional modulation, we used reverse transcriptase,polymerase chain reaction methods to determine the content of discrete synaptosomal mRNAs in rats exposed to the same training protocol. Correlative analyses between behavioral responses and synaptosomal mRNA content showed that GAT-1 mRNA (a prevalent presynaptic component) correlates with avoidances and escapes in rat cerebellum, while glial fibrillary acid protein mRNA (an astrocytic component) correlates with freezings in cerebellum and cerebral cortex. These observations support the hypothesis that synaptic protein synthesis may be transcriptionally regulated. The cellular origin of synaptic transcripts is briefly discussed, with special regard to those present at large distances from neuron somas. © 2009 Wiley-Liss, Inc. [source] Oxytocin mRNA content in the endometrium of non-pregnant womenBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 3 2004Margareta Steinwall Objective To study oxytocin mRNA in the human endometrium at different phases of the menstrual cycle. Design An exploratory study in non-pregnant women. Setting The Department of Obstetrics and Gynecology, Lund University Hospital, Sweden. Participants Thirty-three women of fertile age undergoing hysterectomy or endometrial curettage on routine benign gynaecologic indications. Methods Endometrial tissue was obtained throughout the menstrual cycle. The presence of oxytocin mRNA was investigated by in situ hybridisation and by real time PCR. Main outcome measures Oxytocin mRNA signalling intensity found by in situ hybridisation of tissue obtained at different times of the menstrual cycle. Relative amounts of oxytocin mRNA measured by real time PCR. Results The signal for oxytocin mRNA obtained by in situ hybridisation was more pronounced in glandular epithelial cells than in stromal cells. Furthermore, it was most marked around mid-cycle. The expression of oxytocin mRNA was confirmed by real time PCR. Conclusions The results indicate that oxytocin may be synthesised in the endometrium of non-pregnant women, particularly in the glandular epithelial cells. Hormone released from these sources may have a paracrine action on the uterus. Oxytocin mRNA expression seems to be ovarian hormone dependent with the highest concentration around mid-cycle. [source] Diabetes downregulates presynaptic proteins and reduces basal synapsin I phosphorylation in rat retinaEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2008Heather D. VanGuilder Abstract Diabetic retinopathy can result in vision loss and involves progressive neurovascular degeneration of the retina. This study tested the hypothesis that diabetes decreases the retinal expression of presynaptic proteins involved in synaptic function. The protein and mRNA contents for synapsin I, synaptophysin, vesicle-associated membrane protein 2, synaptosomal-associated protein of 25 kDa and postsynaptic density protein of 95 kDa were measured by immunohistochemistry, immunoblotting and real-time quantitative polymerase chain reaction in whole retinas and retinal synaptosomes from streptozotocin-diabetic and control Sprague,Dawley rats. There was less presynaptic protein immunoreactivity after 1 and 3 months of diabetes than in controls. Discrete synaptophysin-immunoreactive puncta were significantly smaller and fewer in sections from 1- and 3-month diabetic rat retinas than in those from controls. The content of presynaptic proteins was significantly less in whole retinas of 1- and 3-month diabetic rats, and in synaptosomes from 1-month diabetic rats, than in controls. Whole retinas had significantly less mRNA for these genes after 3 months but not 1 month of diabetes, as compared to controls (with the exception of postsynaptic density protein of 95 kDa). In contrast, there was significantly less mRNA for synaptic proteins in synaptosomes of 1-month diabetic rats than in controls, suggesting a localized depletion at synapses. Protein and mRNA for ,-actin and neuron-specific enolase were unchanged by diabetes. The ratio of phosphorylated to total synapsin I was also reduced in whole retina and isolated synaptosomes from 1-month diabetic rats, as compared to controls. These data suggest that diabetes has a profound impact on presynaptic protein expression in the retina, and may provide a mechanism for the well-established defects in vision and the electrophysiological response of the retina in diabetes. [source] The role of steroid hormones in the regulation of vasopressin and oxytocin release and mRNA expression in hypothalamo neurohypophysial explants from the ratEXPERIMENTAL PHYSIOLOGY, Issue 2000Celia D. Sladek Vasopressin and oxytocin release from the neural lobe, and the vasopressin and oxytocin mRNA contents of the supraoptic and paraventricular nuclei are increased by hypertonicity of the extracellular fluid. The factors regulating these parameters can be conveniently studied in perifused explants of the hypothalamo-neurohypophysial system that include the supraoptic nucleus (but not the paraventricular nucleus) with its axonal projections to the neural lobe. Vasopressin and oxytocin release and the mRNA content of these explants respond appropriately to increases in the osmolality of the perifusate. This requires synaptic input from the region of the organum vasculosum of the lamina terminalis. Glutamate is a likely candidate for transmitting osmotic information from the organum vasculosum of the lamina terminalis to the magnocellular neurones, because agonists for excitatory amino acid receptors stimulate vasopressin and oxytocin release, and because increased vasopressin release and mRNA content induced in hypothalamo-neurohypophysial explants by a ramp increase in osmolality are blocked by antagonists of both NMDA (N -methyl-D-aspartate) and non-NMDA glutamate receptors. Osmotically stimulated vasopressin release is also blocked by testosterone, dihydrotestosterone, oestradiol and corticosterone. Both oestrogen and dihydrotestosterone block NMDA stimulation of vasopressin release, and in preliminary studies oestradiol blocked AMPA stimulation of vasopressin release. Thus, steroid inhibition of osmotically stimulated vasopressin secretion may reflect inhibition of mechanisms mediated by excitatory amino acids. Recent studies have demonstrated numerous mechanisms by which steroid hormones may impact upon neuronal function. Therefore, additional work is warranted to understand these effects of the steroid hormones on vasopressin and oxytocin secretion and to elucidate the potential contribution of these mechanisms to regulation of hormone release in vivo. [source] Gene Expression Profiles of Intracellular and Membrane Progesterone Receptor Isoforms in the Mediobasal Hypothalamus During Pro-OestrusJOURNAL OF NEUROENDOCRINOLOGY, Issue 12 2009B. Liu Progesterone action is mediated by its binding to specific receptors. Two progesterone receptor (PR) isoforms (PRA and PRB), three membrane progesterone receptor (mPR) subtypes (mPR,, mPR, and mPR,) and at least one progesterone membrane-binding protein [PR membrane component 1 (PRmc1)] have been identified in reproductive tissues and brain of various species. In the present study, we examined gene expression patterns for PR isoforms, mPR subtypes and PRmc1 in the rat mediobasal hypothalamus (MBH) during pro-oestrus. The mRNA level for each receptor subtype was quantified by a real-time reverse transcriptase-polymerase chain reaction (RT-PCR) at the time points: 13.00 h on dioestrous day 2; 09.00, 13.00, 17.00 and 22.00 h on pro-oestrus; and 13.00 h on oestrus. For PR, one primer set amplified PRA+PRB, whereas a second primer set amplified PRB. As expected, PRA+PRB mRNA expression was greater than PRB in MBH tissue. PRB mRNA levels increased throughout the day on pro-oestrus, with the highest levels being observed at 17.00 h. PRB mRNA levels in the MBH were increased by 2.4- and 3.0-fold at 13.00 and 17.00 h, respectively, on pro-oestrus compared to 13.00 h on dioestrous day 2. There were differential mRNA expression levels for mPRs and PRmc1 in the MBH, with the highest expression for PRmc1 and the lowest for mPR,. The mPR, mRNA contents at 13.00 and 17.00 h on pro-oestrus were increased by 1.5-fold compared to that at 13.00 h on dioestrous day 2. The mPR, mRNA levels at 13.00 and 17.00 h on pro-oestrus were 2.5- and 2.4-fold higher compared to that at 13.00 h on dioestrous day 2, respectively. PRA+PRB, mPR, and PRmc1 mRNA levels did not vary on pro-oestrus. These findings suggest that the higher expression of PRB, mPR, and mPR, in the MBH on pro-oestrous afternoon may influence both genomic and nongenomic mechanisms of progesterone action during the critical pre-ovulatory period. [source] Tobacco Mg protoporphyrin IX methyltransferase is involved in inverse activation of Mg porphyrin and protoheme synthesisTHE PLANT JOURNAL, Issue 2 2005Ali E. Alawady Summary Protoporphyrin, a metabolic intermediate of tetrapyrrole biosynthesis, is metabolized by Mg chelatase and ferrochelatase and is directed into the Mg-branch for chlorophyll synthesis and in the Fe-branch for protoheme synthesis respectively. Regulation of the enzyme activities at the beginning of this branchpoint ensures accurate partition of protoporphyrin, but is still not entirely understood. Transgenic tobacco plants were generated that express antisense or sense RNA for inhibited and excessive expression of Mg protoporphyrin methyltransferase (MgPMT) respectively. This enzyme accepts Mg protoporphyrin from Mg chelatase and catalyses the transfer of a methyl group to the carboxyl group of the C13-propionate side chain. Low MgPMT activity is correlated with reduced Mg chelatase activity and a low synthesis rate of 5-aminolevulinate, but with enhanced ferrochelatase activity. In contrast, high MgPMT activity leads to inverse activity profiles: high activities of Mg chelatase and for 5-aminolevulinate synthesis, but reduced activity of ferrochelatase, indicating a direct influence of MgPMT in combination with Mg chelatase on the metabolic flux of ALA and the distribution of protoporphyrin into the branched pathway. The modified enzyme activities in tetrapyrrole biosynthesis in the transgenic plants can be explained with changes of certain corresponding mRNA contents: increased 5-aminolevulinate synthesis and Mg chelatase activity correlate with enhanced transcript levels of the HemA, Gsa, and CHLH gene encoding glutamyl-tRNA reductase, glutamate-1-semialdehyde aminotransferase and a Mg chelatase subunit respectively. It is proposed that reduced and increased MgPMT activity in chloroplasts is communicated to the cytoplasm for modulating transcriptional activities of regulatory enzymes of the pathway. [source] HLA-A and HLA-B transcription decrease with ageing in peripheral blood leucocytesCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 2 2001C. Le Morvan Immunosenescence involves modifications of humoral and cellular immunity. In a previous study, we have shown a locus-dependent reduction of HLA class-I cell surface expression on peripheral lymphocytes and monocytes with advancing age. Here we report the quantitative analysis of HLA-A and -B transcripts from PBL of 54 healthy subjects aged 21,90 years. Using a competitive RT-PCR method, we observed a significant decrease of HLA-A (P < 0·0001) and -B (P = 0·0025) mRNA contents with increasing age. Secondly, to investigate this locus-dependent alteration of HLA class-I transcription, we performed EMSA using nuclear extracts from PBL of five young (24,31-year-old) and 5 elderly (58,69 years old) donors with locus A and B sequences of the Enh-A as probes. No qualitative variation of EMSA profiles appeared between the two groups of donors with 6 and 4 bandshift for the locus A and B, respectively. Quantitatively, we observed a significant increase of B4 intensity in the elderly group compared to the young group (P < 0·05). These results suggest that the variation of DNA binding protein could contribute to the lower transcription of HLA-A and -B with ageing. These alterations of HLA class-I expression at the transcriptional level could lead to the unresponsiveness of CD8 T cells due to default of antigen presentation with ageing. [source] | |||||||||||||