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Biomedical subjects

M Burnatowska-Hledin

Publications and source records attributed to M Burnatowska-Hledin.

10 recordsLinked to original sources
PubMed2003

VACM-1, a cul-5 gene, inhibits cellular growth by a mechanism that involves MAPK and p53 signaling pathways.

Vasopressin-activated Ca2+-mobilizing (VACM)-1 gene product is a 780-amino acid membrane protein that shares sequence homology with cullins, a family of genes involved in the regulation of cell cycle. However, when expressed in vitro, VACM-1 attenuates basal and vasopressin- and forskolin-induced cAMP production. Mutating the PKA-dependent phosphorylation site in the VACM-1 sequence (S730AVACM-1) prevents this inhibitory effect. To further examine the biological role of VACM-1, we studied the effect of VACM-1 and S730AVACM-1 proteins on cellular proliferation and gene expression in Chinese hamster ovary and COS-1 cells. Cellular proliferation of VACM-1-expressing cell lines was significantly lower compared with that of the vector-transfected cells, whereas it was significantly increased in S730AVACM-1-derived cell lines. Furthermore, expression of VACM-1 but not S730AVACM-1 protein retarded cytokinesis and prevented MAPK phosphorylation. Screening with the Human PathwayFinder-1 GEArray system and subsequent Western blot analysis demonstrated that VACM-1 induces p53 mRNA and protein expression. In summary, VACM-1 inhibits cellular growth by a mechanism that involves cAMP, MAPK phosphorylation, and p53 expression.

Animals↗
PubMed2000

VACM-1, a cullin gene family member, regulates cellular signaling.

Vasopressin-activated Ca(2+)-mobilizing (VACM-1) receptor binds arginine vasopressin (AVP) but does not have amino acid sequence homology with the traditional AVP receptors. VACM-1, however, is homologous with a newly discovered cullin family of proteins that has been implicated in the regulation of cell cycle through the ubiquitin-mediated degradation of cyclin-dependent kinase inhibitors. Because cell cycle processes can be regulated by the transmembrane signal transduction systems, the effects of VACM-1 expression on the Ca(2+) and cAMP-dependent signaling pathway were examined in a stable cell line expressing VACM-1 in VACM-1 transfected COS-1 cells and in cells cotransfected with VACM-1 and the adenylyl cyclase-linked V(2) AVP receptor cDNAs. Expression of the VACM-1 gene reduced basal as well as forskolin- and AVP-stimulated cAMP production. In cells cotransfected with VACM-1 and the V(2) receptor, the AVP- and forskolin-induced increases in adenylyl cyclase activity and cAMP production were inhibited. The inhibitory effect of VACM-1 on cAMP production could be reversed by pretreating cells with staurosporin, a protein kinase A (PKA) inhibitor, or by mutating S730A, the PKA-dependent phosphorylation site in the VACM-1 sequence. The protein kinase C specific inhibitor Gö-6983 further enhanced the inhibitory effect of VACM-1 on AVP-stimulated cAMP production. Finally, AVP stimulated D-myo-inositol 1,4, 5-trisphosphate production both in the transiently transfected COS-1 cells and in the stable cell line expressing VACM-1, but not in the control COS-1 and Chinese hamster ovary cells. Our data demonstrate that VACM-1, the first mammalian cullin protein to be characterized, is involved in the regulation of signaling.

Adenylyl Cyclase Inhibitors↗
PubMed1999

VACM-1 receptor is specifically expressed in rabbit vascular endothelium and renal collecting tubule.

The vasopressin-activated calcium-mobilizing (VACM-1) protein is a novel arginine vasopressin (AVP) receptor that shares sequence homology with a cullin multigene family but not with the AVP receptors. To characterize the VACM-1 receptor, we examined its tissue-specific expression using Northern blot, RT-PCR, and immunostaining analyses. Northern blot hybridization identified a 6. 4-kb cRNA species that was expressed in the rabbit kidney medulla, brain, heart, and ovaries. In human tissue, VACM-1 mRNA is a larger (7.5 kb) cRNA found in the kidney, brain, heart, placenta, and skeletal muscle. VACM-1-specific RT-PCR products were detected in mRNA from rabbit kidney medulla, brain, heart, and mesenteric arteries. No expression of VACM-1 could be detected in rabbit aorta, gastrointestinal tract, or liver. Coimmunostaining with anti-VACM-1 antibodies (Ab) and a specific vascular endothelial cell marker, CD31 monoclonal Ab, localized VACM-1 expression to the vasculature in specific tissues. We identified the kidney cells expressing VACM-1 receptor by coimmunostaining with the following monoclonal Ab, which recognize epitopes in specific segments of the nephron: rct-30 Ab, reactive against the cortical and medullary collecting tubule (CT) cells; mr-omct Ab, reactive against the mitochondria-rich cells of the outer medullary CT; and an Ab specific against the loop of Henle segment. These studies indicated that the VACM-1 receptor is expressed only in the medullary CT. Kidney coimmunostaining with anti-VACM-1 and CD31 Ab identified VACM-1-receptor expression in glomeruli and medullary vascular bundles. These results demonstrate that the novel VACM-1 receptor, expressed in many organs, is localized to the endothelial cells. In the kidney, it is also expressed in the medullary CT cells. Thus VACM-1 may be involved in the regulation of endothelial permeability and water transport in the CT.

Animals↗
PubMed1993

Cloning of an adenosine A1 receptor-encoding gene from rabbit.

A partial cDNA encoding the A1 adenosine receptor (A1AR), which lacks nucleotides coding for the first 74 amino acids (aa), was isolated from a rabbit kidney cDNA library. The missing 5' end sequence was obtained from an overlapping rabbit genomic clone which was found to contain the flanking 5' untranslated region (5'UTR), the first exon and part of the first intron. Together, the cDNA and genomic clones provide the entire open reading frame (ORF) encoding rabbit A1AR. The deduced aa sequence is highly homologous to the canine, rat and bovine A1ARs. These data also indicate that the A1AR gene belongs to the family of intron-containing G-protein-linked receptor genes.

Adenosine↗
PubMed1988

Immunodissection of cortical and medullary thick ascending limb cells from rabbit kidney.

A procedure was developed for isolating thick ascending limb cells from either the outer medulla or the inner cortex from rabbit kidneys. Dispersed cells derived from the medulla or cortex were incubated with goat anti-human uromucoid (Tamm-Horsfall glycoprotein) serum, washed, and applied to culture dishes coated with affinity-purified anti-goat immunoglobulin G. Nonadherent cells were removed by washing. Routinely, 10(6) or 7 X 10(4) adherent cells were obtained per gram of rabbit outer medulla or inner cortex, respectively. Greater than 97% of the adherent cells stained for Tamm-Horsfall antigen, and examination of freshly isolated cells by transmission electron microscopy established that they had morphological properties expected for thick limb cells. Freshly isolated medullary thick limb (MTALH) cells consistently accumulated cAMP in response to arginine vasopressin (AVP), thyrocalcitonin, prostaglandin E2 (PGE2), and glucagon. PGE2, thyrocalcitonin, parathyroid hormone, and AVP, but not isoproterenol or glucagon, reproducibly stimulated cAMP accumulation in freshly isolated cortical thick limb (CTALH) cells. MTALH cells produced immunoreactive PGE2 when incubated with 10 microM arachidonic acid. In summary, large numbers of highly purified and hormonally responsive rabbit MTALH and CTALH cells can be obtained by immunodissection using commercially available antibody preparations. Because the Tamm-Horsfall antigen is present as an extracellular determinant on thick ascending limb epithelia from many species, this general approach likely can be used to isolate CTALH and MTALH cells from most mammalian kidneys.

Animals↗
PubMed1988

Serum and urinary aluminum levels in patients receiving alum-precipitated allergenic extracts.

Indications of aluminum (Al) loading and possible toxicity were sought on three occasions in each of six otherwise healthy patients on maintenance therapy with alum-precipitated allergenic extracts. As compared with age-matched controls receiving conventional aqueous immunotherapy, alum-treated patients had slightly higher levels of serum and urinary Al, suggesting slightly increased body burdens. Neither serum Al levels nor calculated urinary aluminum:creatinine ratios fell outside the broad normal ranges currently accepted for these determinations. Furthermore, no patient showed laboratory or clinical evidence of aluminum toxicity.

Adjuvants, Immunologic↗
PubMed1987

Microcytic anemia in dialysis patients: reversible marker of aluminum toxicity.

Improvement of microcytic anemia after deferoxamine treatment is described in eight long-term dialysis patients with high serum aluminum concentration and other clinical signs of aluminum toxicity. Hematocrit increase of 3 to 19 vol% was associated with correction of microcytosis, significant reduction in abnormal levels of free erythrocyte protoporphyrins, and amelioration of the bone-related symptoms and neurologic signs of aluminum intoxication. Increase in hematocrit, reversal of microcytosis, and reduction in protoporphyrin levels all correlated with the aluminum burden as indicated by the pretreatment serum aluminum levels and by the peak serum aluminum levels during mobilization with deferoxamine. Furthermore, deferoxamine resulted in marked improvement in anemia despite significant reduction in serum ferritin levels. This reversal of microcytosis with deferoxamine provides objective evidence verifying the toxicity of aluminum, and suggests that microcytosis may be an easily detected marker for both clinical diagnosis as well as response to treatment in some cases of aluminum intoxication.

Adult↗
PubMed1986

The metabolism of aluminum and aluminum-related encephalopathy.

The dialysis encephalopathy syndrome is at once the most widely recognized and most severe manifestation of aluminum toxicity. Evidence linking this syndrome and aluminum intoxication is virtually incontrovertible. The syndrome is characterized by speech and motor difficulties, dementia, and seizures. Less widely recognized symptoms include subtle changes in cognition and personality and directional disorientation. Since the widespread use of water treatment, aluminum exposure in the dialysis population has been primarily via intravenous (IV) medications and oral aluminum-containing, phosphate-binding antacid gels. In addition to the encephalopathy syndrome, aluminum has been linked to toxicity in bone, parathyroid gland, RBC, and kidney. These organ toxicities seem to be the result of specific protein enzyme inhibition. Currently identified factors that affect aluminum accumulation and modulate aluminum balance include uremia, renal function, parathyroid hormone withdrawal and suppression, 1,25-dihydroxycholecalciferol, and serum aluminum binding. Impaired renal function is not a prerequisite for increased tissue aluminum burdens. It is likely that aluminum-related disease will be increasingly observed in populations other than those with chronic renal failure.

Aluminum↗
PubMed1985

Effect of aluminum on the renal handling of phosphate in the rat.

The effects of aluminum (Al) on the renal handling of phosphate (Pi) were studied by clearance techniques in the presence and absence of endogenous parathyroid hormone (PTH) and after Pi infusion. In all groups, a 1-h control period was followed by three 1-h experimental periods in which controls continued to receive saline and experimental animals received Al. Glomerular filtration rate, urine flow rate, and plasma sodium (Na) were not significantly changed between periods in any group. In the presence of endogenous PTH, the fractional excretion of phosphate (FEPi) increased significantly after 3 h of Al infusion (6.1 +/- 0.9 to 15.0 +/- 1.8%, P less than 0.05, n = 8), but not in controls (n = 7), while plasma calcium and Pi decreased, suggesting a PTH effect. However, in acutely thyroparathyroidectomized (TPTX) rats the FEPi also increased significantly after 3 h of Al infusion (4.3 +/- 3.0 to 10.6 +/- 4.2%, P less than 0.05, n = 7), but not in controls (n = 6). In TPTX rats infused with Pi where plasma Pi was increased to 10 mg/dl, FEPi increased significantly after 2 and 3 h of Al (7.0 +/- 1.4 to 15.5 +/- 2.1 to 16.9 +/- 2.2%, P less than 0.01, n = 15), but not in controls (n = 8). In this group, changes in FEPi were accompanied by a small but significant increase in FENa but not urinary cAMP. Blood pH was not significantly different between saline and Al-infused rats. These studies indicate that Al infusion inhibits renal Pi reabsorption by a mechanism independent of PTH, blood pH, or cAMP.

Aluminum↗