51
|
Bachs O, Agell N, Carafoli E. Calcium and calmodulin function in the cell nucleus. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1113:259-70. [PMID: 1510999 DOI: 10.1016/0304-4157(92)90041-8] [Citation(s) in RCA: 132] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- O Bachs
- Department of Cell Biology, University of Barcelona, Spain
| | | | | |
Collapse
|
52
|
Abstract
Antibodies raised to two membrane proteins present in rat liver endosomal fractions were used to study changes occurring in the endocytic compartment of hepatocytes during liver regeneration. Antibodies to the 42-kDa subunit (RHL-1) of the asialoglycoprotein receptor showed, by Western blotting of liver microsomes and endosomes, that there was a reduced expression of the receptor in liver 24 h following a partial hepatectomy. Immunocytochemical staining of thin sections of regenerating livers using these antibodies indicated that there was an intracellular relocation of endocytic structures in hepatocytes. The two main endocytic regions immunocytochemically stained in normal liver--one located beneath the sinusoidal plasma membrane and the other abutting the bile canaliculus--were replaced, in regenerating liver, by staining more closely associated with a region underlying the baso-lateral plasma membrane. A 140-kDa pI 4.3 calmodulin-binding protein located in endocytic and plasma membranes was also demonstrated, using a radio-iodinated calmodulin-binding assay, to be present at reduced levels in endosomes isolated from regenerating livers. Antibodies to this calmodulin-binding protein stained the hepatocyte's cytoplasm in a punctate manner. However, in regenerating liver, the staining was located in regions underlying the baso-lateral and apical plasma membrane of hepatocytes. Together, the results demonstrate that a reorganization of the endocytic compartment has occurred in hepatocytes 24 h following hepatectomy, with two endosomal proteins becoming relocated to a region below the baso-lateral-apical surface regions of hepatocytes.
Collapse
Affiliation(s)
- C Enrich
- Departamento de Biología Celular, Facultad de Medicina, Universidad de Barcelona, Spain
| | | | | |
Collapse
|
53
|
Basheeruddin K, Rechtoris C, Mazzone T. Transcriptional and post-transcriptional control of apolipoprotein E gene expression in differentiating human monocytes. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)48417-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
|
54
|
Cocco L, Martelli AM, Gilmour RS, Rana RA, Barnabei O, Manzoli FA. Changes in inositol lipid metabolism and protein kinase C translocation in nuclei of mitogen stimulated Swiss 3T3 cells. ADVANCES IN ENZYME REGULATION 1992; 32:91-103. [PMID: 1323206 DOI: 10.1016/0065-2571(92)90010-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The correlation between changes in nuclear polyphosphoinositide levels preceding PKC translocation to the nucleus and the onset of DNA synthesis has been discussed. Using two different clones of Swiss 3T3 fibroblasts belonging to the same original cell line, one of which is unresponsive to mitogenic stimulation with IGF-I on its own or in combination with bombesin, it has been observed that a rapid and transient breakdown of nuclear PIP and PIP2 occurs only in responsive cells and this precedes the translocation of PKC to the nucleus, as evidenced by immunochemical analysis as well as by enzymatic activity. Therefore, it seems that a direct link exists between nuclear polyphosphoinositide metabolism, PKC translocation to the nucleus and cell division. Since IGF-I acts at the plasma membrane through a tyrosine kinase receptor it seems that the mitogenic stimulation induced by this factor utilizes different signalling pathways at the plasma membrane and at the nucleus. Because of the evidence that type I IGF receptor is expressed in both responsive and unresponsive cells and that the receptor machinery at the plasma membrane is active the lack of the transient changes in nuclear inositol lipids and of PKC translocation in unresponsive cells further suggests that the cell nucleus is capable of an autonomous signalling system based on polyphosphoinositide metabolism.
Collapse
Affiliation(s)
- L Cocco
- Institute of Human Anatomy, University of Bologna, Italy
| | | | | | | | | | | |
Collapse
|
55
|
Berezney R. The nuclear matrix: a heuristic model for investigating genomic organization and function in the cell nucleus. J Cell Biochem 1991; 47:109-23. [PMID: 1757479 DOI: 10.1002/jcb.240470204] [Citation(s) in RCA: 195] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Despite significant advances in deciphering the molecular events underlying genomic function, our understanding of these integrated processes inside the functioning cell nucleus has, until recently, met with only very limited success. A major conundrum has been the "layers of complexity" characteristic of all cell structure and function. To understand how the cell nucleus functions, we must also understand how the cell nucleus is put together and functions as a whole. The value of this neo-holistic approach is demonstrated by the enormous progress made in recent years in identifying a wide variety of nuclear functions associated with the nuclear matrix. In this article we summarize basic properties of in situ nuclear structure, isolated nuclear matrix systems, nuclear matrix-associated functions, and DNA replication in particular. Emphasis is placed on identifying current problems and directions of research in this field and illustrating the intrinsic heuristic value of this global approach to genomic organization and function.
Collapse
Affiliation(s)
- R Berezney
- Department of Biological Sciences, State University of New York, Buffalo 14260
| |
Collapse
|
56
|
Vendrell M, Aligué R, Bachs O, Seratosa J. Presence of calmodulin and calmodulin-binding proteins in the nuclei of brain cells. J Neurochem 1991; 57:622-8. [PMID: 2072106 DOI: 10.1111/j.1471-4159.1991.tb03793.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The nuclear calmodulin levels have been measured in rat neurons and glial cells. The values are 1.0 and 1.1 micrograms/mg of protein, respectively. These levels are about threefold higher than those in the nuclei of rat liver cells. We have also investigated the presence of several calmodulin-binding proteins in the nuclei of both brain cellular types. As similarly observed in the nuclei of liver cells, we detected the presence of alpha-spectrin and a 62-kDa calmodulin-binding protein (p62) in the nuclei of neurons and glial cells by immunoblotting and immunocytochemical methods. Both proteins are enriched in the purified nuclear matrix samples from both cellular types. In contrast to that occurring in rat hepatocytes, we have not been able to detect, by immunoblotting methods, caldesmon in the nuclear matrices of neurons and glial cells. The immunocytochemical studies suggest, however, that caldesmon can be present in the nuclei but in a fraction distinct from the nuclear matrices.
Collapse
Affiliation(s)
- M Vendrell
- Departmento de Farmacología y Toxicología, CSIC, Barcelona, Spain
| | | | | | | |
Collapse
|
57
|
Anraku Y, Ohya Y, Iida H. Cell cycle control by calcium and calmodulin in Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1093:169-77. [PMID: 1863597 DOI: 10.1016/0167-4889(91)90119-i] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Y Anraku
- Department of Biology, Faculty of Science, University of Tokyo, Japan
| | | | | |
Collapse
|
58
|
Inhibitory effect of calcium-binding protein regucalcin on Ca2(+)-activated DNA fragmentation in rat liver nuclei. FEBS Lett 1991; 279:281-4. [PMID: 2001740 DOI: 10.1016/0014-5793(91)80168-3] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Incubation of isolated rat liver nuclei with ATP, NAD+, and micromolar Ca2+ concentrations of various metal ions resulted in extensive DNA hydrolysis. Half-maximal activity occurred with 1.0 microM Ca2+ added, and saturation of the process was observed with 10 microM Ca2+. The Ca2+ (10 microM)-activated DNA fragmentation was inhibited by the presence of Ca2(+)-binding protein regucalcin isolated from rat liver cytosol. The inhibitory effect of regucalcin was complete at 0.5 microM. At 25 microM Ca2+ added, such an effect of regucalcin (1.0 microM) was not seen. Regucalcin also inhibited Ca2(+)-activated DNA fragmentation in the presence of calmodulin (10 and 20 micrograms). The results show that regucalcin can inhibit the Ca2(+)-activated DNA fragmentation due to binding the metal, suggesting a role in regulation of liver nuclear functions.
Collapse
|
59
|
Martelli AM, Gilmour RS, Manzoli FA, Cocco L. Calcium free inositol (1,4,5)-trisphosphate stimulates protein kinase C dependent protein phosphorylation in nuclei isolated from mitogen-treated Swiss 3T3 cells. Biochem Biophys Res Commun 1990; 173:149-55. [PMID: 2124110 DOI: 10.1016/s0006-291x(05)81034-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
As a step towards the elucidation of the role played by nuclear polyphosphoinositides, we have investigated the effect of exogenous calcium free inositol (1,4,5)-trisphosphate on the in vitro phosphorylation of proteins in nuclei prepared from Swiss 3T3 cells treated with bombesin and insulin-like growth factor I. When present in combination with phosphatidylserine, inositol (1,4,5)-trisphosphate enhanced the phosphorylation of two nuclear proteins, Mr 21,000 and 31,000, as well as of exogenous histone H1, to the same extent as a combination of phosphatidylserine and diacylglycerol. Inositol (1,4,5)-trisphosphate alone had no effect. This stimulation could be abolished by the protein kinase C inhibitor sphingosine and by EGTA, while could be restored by a combination of phosphatidylserine and exogenous Ca+(+) ions. These results raise the possibility that inositol (1,4,5)-trisphosphate is capable of liberating Ca+(+) ions from a nuclear store thus stimulating protein kinase C activity.
Collapse
Affiliation(s)
- A M Martelli
- Istituto di Anatomia Umana Normale, Bologna, Italy
| | | | | | | |
Collapse
|
60
|
Abstract
Hepatic parenchymal cells maintain intracellular total and cytosolic free Ca2+ levels by: entry of Ca2+ through channels, extrusion of Ca2+ by an outwardly directed Ca2+ pump, and controlled sequestration into intracellular pools. The mechanism of Ca2+ inflow is poorly characterized. The plasma membrane Ca2+ channels seem to share some of the characteristics of Ca2+ channels in excitable cells, but also differ from them. The outwardly directed plasma membrane Ca2(+)-ATPase is a calmodulin independent, P-type enzyme. Ca2+ uptake into the endoplasmic reticulum is due to the activity of a different Ca2(+)-ATPase, which is similar in molecular weight and shares antigenic determinants with the sarcoplasmic reticulum enzyme. In addition, mitochondria and nuclei also take up calcium. The exact mechanism by which Ca2+ is released from intracellular organelles is not well known. Several mechanisms for Ca2+ release from the endoplasmic reticulum were reported, including IP3 and GTP-induced. The most effective identified way of eliciting Ca2+ release from microsomal fraction is by the oxidation of critical -SH groups. This mechanism is likely to be involved in the rise of cytosolic Ca2+ observed in many situations of hepatocellular injury. In addition to being sequestered into subcellular organelles, some of the intracellular Ca2+ is bound to specific Ca2+ binding proteins. Both calmodulin and members of the annexin family were identified in the liver. Stimulation of the liver with gluconeogenic hormones results in increased Ca2+ entry into the cell, the release of Ca2+ from intracellular pools, and an oscillatory increase in free cytosolic Ca2+ levels. Extensive research is still needed for the elucidation of the exact mechanisms by which these events occur.
Collapse
Affiliation(s)
- N Kraus-Friedmann
- Department of Physiology and Cell Biology, University of Texas Medical School, Houston
| |
Collapse
|
61
|
Calmodulin-binding proteins in the nuclei of quiescent and proliferatively activated rat liver cells. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)44793-4] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
|
62
|
Campanella C, Carotenuto R, Gabbiani G. Antispectrin antibodies stain the oocyte nucleus and the site of fertilization channels in the egg of Discoglossus pictus (Anura). Mol Reprod Dev 1990; 26:134-42. [PMID: 1695511 DOI: 10.1002/mrd.1080260207] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In Discoglossus pictus eggs, only the dimple contains ionic channels active at fertilization; in particular, chloride channels are found in the central portion of the dimple, which is also the site of sperm penetration. Moreover the dimple hosts an imposing cytoskeleton, consisting of a cortical network and bundles of microfilaments extending from the microvilli. Since spectrin cross links actin and is connected through ankyrin to anion transporters in the plasma membrane of erythrocytes as well as to anion channels in other cells, we studied, in D. pictus egg, the relationship between the localization of spectrin and the high polarization of ionic channels and cytoskeletal organization. By means of immunocytochemistry, we localized spectrin exclusively in the egg dimple. In an attempt to trace back the source of spectrin localization, we immunostained sections of D. pictus ovary and localized spectrin in the nuclei of previtellogenic oocytes, where actin is also present. Antispectrin staining remained until germinal vesicle breakdown. By contrast, a cortical localization was found only when the oocytes divided into two hemispheres and into the germinative area (GA), which, after germinal vesicle breakdown, gives rise to the dimple. At this stage the antispectrin signal was particularly strong in the GA. Using Rho-pialloidin, we also established that spectrin is generally present where F-actin is found. However, spectrin and F-actin do not have the same pattern of fluorescence. In conclusion, our data suggest that spectrin may play a role in oocyte and egg polarity. In eggs, it could be instrumental in anchoring to the cytoskeleton membrane proteins such as receptors and ionic channels, including chloride-permeable channels.
Collapse
Affiliation(s)
- C Campanella
- Dipartimento di Scienze e Tecnologie Biomediche e di Biometria, Università di L'Aquila, Collemaggio, Italy
| | | | | |
Collapse
|
63
|
Falchetto R, Leutenegger S, Bachs O, Serratosa J, Bloemhard Y, Gazzotti P. Isolation of rat liver spectrin and identification of functional domains. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1039:73-80. [PMID: 2354203 DOI: 10.1016/0167-4838(90)90228-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Immunohistochemical studies carried out with liver sections show that spectrin is uniformly distributed along the whole plasma membrane of hepatocytes. The bilecanalicular spectrin is released during the purification of liver subplasma membrane fractions, whereas most of the basolateral spectrin remains tightly bound to the membrane. Spectrin associated with the basolateral membranes has been purified and its subunits isolated. The alpha-subunit retains the ability to bind both calmodulin and actin. Fragments have been obtained either by chemical or by proteolytical digestion of the 240 kDa alpha-subunit. Treatment with CNBr yields fragments of about 30 kDa which bind actin and calmodulin. Digestion with Staphylococcus aureus V-8 proteinase yields a calmodulin-binding fragment of 27 kDa and an actin-binding fragment of 31 kDa.
Collapse
Affiliation(s)
- R Falchetto
- Laboratory of Biochemistry, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
| | | | | | | | | | | |
Collapse
|
64
|
Dypbukt JM, Thor H, Nicotera P. Intracellular Ca2+ chelators prevent DNA damage and protect hepatoma 1C1C7 cells from quinone-induced cell killing. FREE RADICAL RESEARCH COMMUNICATIONS 1990; 8:347-54. [PMID: 2354810 DOI: 10.3109/10715769009053368] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Exposure of hepatoma 1c1c7 cells to 2,3-dimethoxy-1,4-naphthoquinone (DMNQ) resulted in a sustained elevation of cytosolic Ca2+, DNA single strand breaks and cell killing. DNA single strand break formation was prevented when cells were preloaded with either of the intracellular Ca2+ chelators, Quin 2 or BAPTA, to buffer the increase in cytosolic Ca2+ concentration induced by the quinone. DMNQ caused marked NAD+ depletion which was prevented when cells were preincubated with 3-aminobenzamide, an inhibitor of nuclear poly-(ADP-ribose)-synthetase activity, or with either of the two Ca2+ chelators. However, 3-aminobenzamide did not protect the hepatoma cells from loss of viability. Our results indicate that quinone-induced DNA damage, NAD+ depletion and cell killing are mediated by a sustained elevation of cytosolic Ca2+.
Collapse
Affiliation(s)
- J M Dypbukt
- Department of Toxicology, Karolinska Institute, Stockholm, Sweden
| | | | | |
Collapse
|
65
|
Pujol MJ, Soriano M, Aligué R, Carafoli E, Bachs O. Effect of α-adrenergic blockers on calmodulin association with the nuclear matrix of rat liver cells during proliferative activation. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)47234-7] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
66
|
Auwerx JH, Deeb S, Brunzell JD, Wolfbauer G, Chait A. Lipoprotein lipase gene expression in THP-1 cells. Biochemistry 1989; 28:4563-7. [PMID: 2765502 DOI: 10.1021/bi00437a009] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Lipoprotein lipase (LPL) mRNA levels are under the control of signals that activate phospholipase C, resulting in activation of protein kinase C (PKC) and mobilization of intracellular Ca2+ in the human monocytic leukemia cell line THP-1. Induction of LPL in THP-1 cells appears to be mediated by PKC since it was affected by both phorbol 12-myristate 13-acetate (PMA) and a diacylglycerol analogue. This induction was blocked by the specific PKC inhibitor H-7. Although Ca2+ mobilization by the ionophore A23187 also induced LPL mRNA, the mechanism is most likely independent of activation of the Ca2+/calmodulin protein kinase. Depletion of cells of PKC made them refractory to induction by A23187, suggesting that Ca2+ mobilization acts by activating PKC. Addition of cycloheximide (CHX) to undifferentiated THP-1 cells resulted in a transient increase in steady-state mRNA levels (3-fold). Sustained superinduction of LPL mRNA occurred when PMA and CHX were added simultaneously. These results suggest that the level of LPL mRNA is regulated either by a labile regulatory protein, which represses transcription of the LPL gene, or by a protein affecting mRNA stability.
Collapse
Affiliation(s)
- J H Auwerx
- Department of Medicine, University of Washington, Seattle 98195
| | | | | | | | | |
Collapse
|
67
|
Jones DP, McConkey DJ, Nicotera P, Orrenius S. Calcium-activated DNA Fragmentation in Rat Liver Nuclei. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)83363-4] [Citation(s) in RCA: 209] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
68
|
McConkey DJ, Nicotera P, Hartzell P, Bellomo G, Wyllie AH, Orrenius S. Glucocorticoids activate a suicide process in thymocytes through an elevation of cytosolic Ca2+ concentration. Arch Biochem Biophys 1989; 269:365-70. [PMID: 2537063 DOI: 10.1016/0003-9861(89)90119-7] [Citation(s) in RCA: 391] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Glucocorticoid hormones kill immature thymocytes through the induction of a suicide process commonly referred to as "apoptosis." A characteristic marker for this process is the stimulation of endogenous endonuclease activity which results in the extensive cleavage of cell chromatin. In an attempt to characterize the biochemical events involved in this process, we studied the role of Ca2+ in glucocorticoid-induced DNA fragmentation and cell killing in thymocytes. Treatment of thymocytes from immature rats with the synthetic glucocorticoid methylprednisolone resulted in extensive DNA fragmentation which was preceded by an early, sustained increase in cytosolic Ca2+ concentration. This increase in Ca2+ level was blocked by cycloheximide and actinomycin D, inhibitors of de novo protein and mRNA synthesis, respectively. Prevention of the Ca2+ increase by buffering cytosolic Ca2+ with quin-2, or through incubation of the thymocytes in a "Ca2+-free" medium, prevented endonuclease activation and cell killing. Inhibitors of calmodulin also prevented DNA fragmentation without inhibiting the glucocorticoid-stimulated elevation of cytosolic Ca2+ concentration. The Ca2+ increase appeared to be due to the action of a heat-labile cytosolic factor, synthesized in response to glucocorticoids, which facilitated the influx of extracellular Ca2+. Our findings suggest that glucocorticoids induce thymocyte suicide through an elevation of cytosolic Ca2+ concentration resulting in endonuclease activation, DNA fragmentation, and cell death.
Collapse
Affiliation(s)
- D J McConkey
- Department of Toxicology, Karolinska Institutet, Stockholm, Sweden
| | | | | | | | | | | |
Collapse
|
69
|
Ohya Y, Anraku Y. A galactose-dependent cmd1 mutant of Saccharomyces cerevisiae: involvement of calmodulin in nuclear division. Curr Genet 1989; 15:113-20. [PMID: 2663189 DOI: 10.1007/bf00435457] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The coding region of a yeast calmodulin gene was fused to a galactose-inducible GAL1 promoter, and a conditional-lethal mutant of Saccharomyces cerevisiae, in which the expression of calmodulin was regulated by galactose, was constructed. The mutant grew normally in galactose medium, but in glucose medium, in which the promoter was repressed, it ceased growing after 12-15 h. The growth arrest was associated with a decrease in intracellular calmodulin levels: after 12 h, no intracellular calmodulin protein was detectable. Analysis of the terminal phenotype showed that when the cell stopped growing, it had a bud, a nucleus after S-phase and a short mitotic spindle. Thus, the defect was mainly in nuclear division. Bud growth was partially inhibited in these cells: 27% of the cells stopped growing with a small bud. Furthermore, calmodulin-deficient cells showed elevated rates of chromosome loss, possibly as the result of a defect in the precise segregation of chromosomes.
Collapse
Affiliation(s)
- Y Ohya
- Department of Biology, Faculty of Science, University of Tokyo, Japan
| | | |
Collapse
|
70
|
Ohya Y, Anraku Y. Conditional-lethal mutant of calmodulin in yeast. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1989; 255:481-90. [PMID: 2694810 DOI: 10.1007/978-1-4684-5679-0_51] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Y Ohya
- Department of Biology, Faculty of Science, University of Tokyo, Japan
| | | |
Collapse
|
71
|
Affiliation(s)
- M L Veigl
- Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106
| | | | | |
Collapse
|
72
|
Abstract
We report the isolation and characterization of a human genomic clone encoding a calmodulin-like pseudogene. It contains an open reading frame of 444 nucleotides, not interrupted by introns. The nucleotide sequence of the open reading frame shows 80%, 71% and 69% identity to the previously reported human calmodulin cDNAs lambda ht6 [17], hCWP [22], and lambda hCE1 [23], respectively. The derived amino acid sequence has only 85% identity to vertebrate calmodulin, but shows four potentially functional Ca2+-binding loops. In the human tissues tested, this pseudogene is not expressed, though gene structure including promoter elements and a putative polyadenylation site seems to be intact.
Collapse
Affiliation(s)
- M Koller
- Laboratory for Biochemistry, Swiss Federal Institute of Technology (ETH), Zürich
| | | |
Collapse
|
73
|
Serratosa J, Pujol MJ, Bachs O, Carafoli E. Rearrangement of nuclear calmodulin during proliferative liver cell activation. Biochem Biophys Res Commun 1988; 150:1162-9. [PMID: 3342064 DOI: 10.1016/0006-291x(88)90751-6] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Calmodulin increases about three-fold in rat liver nuclei after partial hepatectomy. The increase is maximal after 24 hours, when DNA synthesis is also maximal. During the same time re-distribution of calmodulin within the nuclear structure takes place, leading to its association with the nuclear matrix. Incubation of normal rat liver nuclei with Ca2+ induces association of calmodulin with the matrix, indicating that the re-distribution of calmodulin during the replicative period is related to the increase in nuclear Ca2+. The nuclear matrix contains several calmodulin binding proteins of which one, having Mr of 130 kDa, has been identified as myosin light chain kinase (MLCK). Three acceptor proteins, having Mr of 120, 65, and 60 kDa decrease 24 hours after partial hepatectomy, MLCK and a protein of Mr 150 kDa instead increase.
Collapse
Affiliation(s)
- J Serratosa
- Departamento de Biologia Celular, Facultad de Medicina, Universidad de Barcelona, Spain
| | | | | | | |
Collapse
|