Mutation in the bimD gene of Aspergillus nidulans confers a conditional mitotic block and sensitivity to DNA damaging agents.

Genetics ◽  
1993 ◽  
Vol 134 (4) ◽  
pp. 1085-1096
Author(s):  
S H Denison ◽  
E Käfer ◽  
G S May
Keyword(s):  
Aspergillus Nidulans ◽  
Leucine Zipper ◽  
Temperature Sensitive ◽  
Sequence Motifs ◽  
Mitotic Progression ◽  
Dna Damaging Agents ◽  
Mitotic Block ◽  
Increased Sensitivity ◽  
Carboxyl Terminal ◽  
The Relationship

Abstract Mutation in the bimD gene of Aspergillus nidulans results in a mitotic block in anaphase characterized by a defective mitosis. Mutation in bimD also confers, at temperatures permissive for the mitotic arrest phenotype, an increased sensitivity to DNA damaging agents, including methyl methanesulfonate and ultraviolet light. In order to better understand the relationship between DNA damage and mitotic progression, we cloned the bimD gene from Aspergillus. A cosmid containing the bimD gene was identified among pools of cosmids by cotransformation with the nutritional selective pyrG gene of a strain carrying the recessive, temperature-sensitive lethal bimD6 mutation. The bimD gene encodes a predicted polypeptide of 166,000 daltons in mass and contains amino acid sequence motifs similar to those found in some DNA-binding transcription factors. These sequences include a basic domain followed by a leucine zipper, which together are called a bZIP motif, and a carboxyl-terminal domain enriched in acidic amino acids. Overexpression of the wild-type bimD protein resulted in an arrest of the nuclear division cycle that was reversible and determined to be in either the G1 or S phase of the cell cycle. Our data suggest that bimD may play an essential regulatory role relating to DNA metabolism which is required for a successful mitosis.

scholarly journals Suppression of the bimC4 mitotic spindle defect by deletion of klpA, a gene encoding a KAR3-related kinesin-like protein in Aspergillus nidulans.

1993 ◽  
Vol 120 (1) ◽  
pp. 153-162 ◽  
Author(s):  
M J O'Connell ◽  
P B Meluh ◽  
M D Rose ◽  
N R Morris
Keyword(s):  
Aspergillus Nidulans ◽  
Mitotic Spindle ◽  
Structural Similarity ◽  
Temperature Sensitive ◽  
Gene Encoding ◽  
Expression Studies ◽  
Primary Amino ◽  
And Function ◽  
Spindle Function ◽  
The Relationship

To investigate the relationship between structure and function of kinesin-like proteins, we have identified by polymerase chain reaction (PCR) a new kinesin-like protein in the filamentous fungus Aspergillus nidulans, which we have designated KLPA. DNA sequence analysis showed that the predicted KLPA protein contains a COOH terminal kinesin-like motor domain. Despite the structural similarity of KLPA to the KAR3 and NCD kinesin-like proteins of Saccharomyces cerevisiae and Drosophila melanogaster, which also posses COOH-terminal kinesin-like motor domains, there are no significant sequence similarities between the nonmotor or tail portions of these proteins. Nevertheless, expression studies in S. cerevisiae showed that klpA can complement a null mutation in KAR3, indicating that primary amino acid sequence conservation between the tail domains of kinesin-like proteins is not necessarily required for conserved function. Chromosomal deletion of the klpA gene exerted no observable mutant phenotype, suggesting that in A. nidulans there are likely to be other proteins functionally redundant with KLPA. Interestingly, the temperature sensitive phenotype of a mutation in another gene, bimC, which encodes a kinesin-like protein involved in mitotic spindle function in A. nidulans, was suppressed by deletion of klpA. We hypothesize that the loss of KLPA function redresses unbalanced forces within the spindle caused by mutation in bimC, and that the KLPA and BIMC kinesin-like proteins may play opposing roles in spindle function.

Identification of a Topoisomerase I Mutant, scsA1, as an Extragenic Suppressor of a Mutation in scaANBS1, the Apparent Homolog of Human Nibrin in Aspergillus nidulans

Genetics ◽  
2003 ◽  
Vol 164 (3) ◽  
pp. 935-945 ◽  
Author(s):  
Marcia R Z Kress Fagundes ◽  
Larissa Fernandes ◽  
Marcela Savoldi ◽  
Steven D Harris ◽  
Maria H S Goldman ◽  
...  
Keyword(s):  
Dna Damage ◽  
Aspergillus Nidulans ◽  
Topoisomerase I ◽  
Cell Cycle Checkpoint ◽  
Dna Double Strand Breaks ◽  
Dna Damaging Agents ◽  
Cycle Checkpoint ◽  
Increased Sensitivity ◽  
Cellular Dna ◽  
Extragenic Suppressors

Abstract The Mre11-Rad50-Nbs1 protein complex has emerged as a central player in the human cellular DNA damage response, and recent observations suggest that these proteins are at least partially responsible for the linking of DNA damage detection to DNA repair and cell cycle checkpoint functions. Mutations in scaANBS1, which encodes the apparent homolog of human nibrin in Aspergillus nidulans, inhibit growth in the presence of the antitopoisomerase I drug camptothecin. This article describes the selection and characterization of extragenic suppressors of the scaA1 mutation, with the aim of identifying other proteins that interfere with the pathway or complex in which the ScaA would normally be involved. Fifteen extragenic suppressors of the scaA1 mutation were isolated. The topoisomerase I gene can complement one of these suppressors. Synergistic interaction between the scaANBS1 and scsATOP1 genes in the presence of DNA-damaging agents was observed. Overexpression of topoisomerase I in the scaA1 mutant causes increased sensitivity to DNA-damaging agents. The scsATOP1 and the scaANBS1 gene products could functionally interact in pathways that either monitor or repair DNA double-strand breaks.

scholarly journals Suppressors of a Saccharomyces cerevisiae pkc1 mutation identify alleles of the phosphatase gene PTC1 and of a novel gene encoding a putative basic leucine zipper protein.

Genetics ◽  
1995 ◽  
Vol 141 (4) ◽  
pp. 1275-1285 ◽  
Author(s):  
K N Huang ◽  
L S Symington
Keyword(s):  
Protein Kinase ◽  
Leucine Zipper ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Growth Defect ◽  
Temperature Sensitive ◽  
Gene Encoding ◽  
Basic Leucine Zipper ◽  
Mapk Cascades ◽  
Synthetically Lethal

Abstract The PKC1 gene product, protein kinase C, regulates a mitogen-activated protein kinase (MAPK) cascade, which is implicated in cell wall metabolism. Previously, we identified the pkc1-4 allele in a screen for mutants with increased rates of recombination, indicating that PKC1 may also regulate DNA metabolism. The pkc1-4 allele also conferred a temperature-sensitive (ts) growth defect. Extragenic suppressors were isolated that suppress both the ts and hyperrecombination phenotypes conferred by the pkc1-4 mutation. Eight of these suppressors for into two complementation groups, designated KCS1 and KCS2. KCS1 was cloned and found to encode a novel protein with homology to the basic leucine zipper family of transcription factors. KCS2 is allelic with PTC1, a previously identified type 2C serine/threonine protein phosphatase. Although mutation of either KCS1 or PTC1 causes little apparent phenotype, the kcs1 delta ptc1 delta double mutant fails to grow at 30 degrees. Furthermore, the ptc1 deletion mutation is synthetically lethal in combination with a mutation in MPK1, which encodes a MAPK homologue proposed to act in the PKC1 pathway. Because PTC1 was initially isolated as a component of the Hog1p MAPK pathway, it appears that these two MAPK cascades share a common regulatory feature.

Regulation of Septum Formation in Aspergillus nidulans by a DNA Damage Checkpoint Pathway

Genetics ◽  
1998 ◽  
Vol 148 (3) ◽  
pp. 1055-1067
Author(s):  
Steven D Harris ◽  
Peter R Kraus
Keyword(s):  
Dna Damage ◽  
Aspergillus Nidulans ◽  
Cellular Response ◽  
Dna Damage Checkpoint ◽  
Temperature Sensitive ◽  
Dna Metabolism ◽  
Chromosomal Dna ◽  
Checkpoint Response ◽  
Septum Formation ◽  
Checkpoint Pathway

Abstract In Aspergillus nidulans, germinating conidia undergo multiple rounds of nuclear division before the formation of the first septum. Previous characterization of temperature-sensitive sepB and sepJ mutations showed that although they block septation, they also cause moderate defects in chromosomal DNA metabolism. Results presented here demonstrate that a variety of other perturbations of chromosomal DNA metabolism also delay septum formation, suggesting that this is a general cellular response to the presence of sublethal DNA damage. Genetic evidence is provided that suggests that high levels of cyclin-dependent kinase (cdk) activity are required for septation in A. nidulans. Consistent with this notion, the inhibition of septum formation triggered by defects in chromosomal DNA metabolism depends upon Tyr-15 phosphorylation of the mitotic cdk p34nimX. Moreover, this response also requires elements of the DNA damage checkpoint pathway. A model is proposed that suggests that the DNA damage checkpoint response represents one of multiple sensory inputs that modulates p34nimX activity to control the timing of septum formation.

scholarly journals p53-dependent and p53-independent activation of apoptosis in mammary epithelial cells reveals a survival function of EGF and insulin.

1995 ◽  
Vol 128 (6) ◽  
pp. 1185-1196 ◽  
Author(s):  
G R Merlo ◽  
F Basolo ◽  
L Fiore ◽  
L Duboc ◽  
N E Hynes
Keyword(s):  
Mammary Epithelial Cells ◽  
P53 Protein ◽  
Survival Function ◽  
Mammary Epithelial ◽  
Nuclear Accumulation ◽  
Temperature Sensitive ◽  
Dna Damaging Agents ◽  
A Cells ◽  
Hc11 Cells ◽  
P53 Tumor Suppressor Protein

The p53 tumor suppressor protein has been implicated as a mediator of programmed cell death (PCD). A series of nontransformed mammary epithelial cell (MEC) lines were used to correlate p53 function with activation of PCD. Treatment of MECs expressing mutant, inactive, or no p53 with DNA-damaging agents did not induce apoptosis. Upon introduction of temperature-sensitive p53 into HC11 cells, which lack wild-type (wt) p53, PCD was observed after mitomycin treatment at 32 degrees, when the ts p53 protein is in wt conformation. Thus, wt p53 mediates activation of PCD in response to mitomycin in HC11 cells. Treatment of the MCF10-A cells, which express wt p53, with various DNA-damaging agents led to nuclear accumulation of p53. Only mitomycin treatment led to an increase in the number of apoptotic nuclei. ErbB-2-transformed MCF10-A cells responded to mitomycin, cisplatin, and 5-Fl-uracil, suggesting that signaling from activated ErbB-2 enhances the cells ability to respond to DNA damage. A combination of high cell density and serum-free medium induces apoptosis in all MECs tested, irrespective of their p53 status. Under these conditions, EGF or insulin act as survival factors in preventing PCD. These data might elucidate some aspects of breast involution and tumorigenesis.

scholarly journals Aspergillus nidulans Protein O-Mannosyltransferases Play Roles in Cell Wall Integrity and Developmental Patterning

2009 ◽  
Vol 8 (10) ◽  
pp. 1475-1485 ◽  
Author(s):  
Thanyanuch Kriangkripipat ◽  
Michelle Momany
Keyword(s):  
Cell Wall ◽  
Aspergillus Nidulans ◽  
Double Mutant ◽  
Elevated Temperatures ◽  
Cell Wall Integrity ◽  
Wild Type ◽  
Spatial Cues ◽  
Developmental Patterning ◽  
In The Wild ◽  
Increased Sensitivity

ABSTRACT Protein O-mannosyltransferases (Pmts) initiate O-mannosyl glycan biosynthesis from Ser and Thr residues of target proteins. Fungal Pmts are divided into three subfamilies, Pmt1, -2, and -4. Aspergillus nidulans possesses a single representative of each Pmt subfamily, pmtA (subfamily 2), pmtB (subfamily 1), and pmtC (subfamily 4). In this work, we show that single Δpmt mutants are viable and have unique phenotypes and that the ΔpmtA ΔpmtB double mutant is the only viable double mutant. This makes A. nidulans the first fungus in which all members of individual Pmt subfamilies can be deleted without loss of viability. At elevated temperatures, all A. nidulans Δpmt mutants show cell wall-associated defects and increased sensitivity to cell wall-perturbing agents. The Δpmt mutants also show defects in developmental patterning. Germ tube emergence is early in ΔpmtA and more frequent in ΔpmtC mutants than in the wild type. In ΔpmtB mutants, intrahyphal hyphae develop. All Δpmt mutants show distinct conidiophore defects. The ΔpmtA strain has swollen vesicles and conidiogenous cells, the ΔpmtB strain has swollen conidiophore stalks, and the ΔpmtC strain has dramatically elongated conidiophore stalks. We also show that AN5660, an ortholog of Saccharomyces cerevisiae Wsc1p, is modified by PmtA and PmtC. The Δpmt phenotypes at elevated temperatures, increased sensitivity to cell wall-perturbing agents and restoration to wild-type growth with osmoticum suggest that A. nidulans Pmts modify proteins in the cell wall integrity pathway. The altered developmental patterns in Δpmt mutants suggest that A. nidulans Pmts modify proteins that serve as spatial cues.

scholarly journals DNA topoisomerases as repair enzymes: mechanism(s) of action and regulation by p53.

1998 ◽  
Vol 45 (2) ◽  
pp. 535-544 ◽  
Author(s):  
A K Larsen ◽  
C Gobert ◽  
C Gilbert ◽  
J Markovits ◽  
K Bojanowski ◽  
...  
Keyword(s):  
Topoisomerase Ii ◽  
Nitrogen Mustard ◽  
Dna Recombination ◽  
Dna Lesions ◽  
Dna Topoisomerases ◽  
Repair Enzymes ◽  
Dna Damaging Agents ◽  
Damage Recognition ◽  
Cellular Sensitivity ◽  
Increased Sensitivity

DNA topoisomerases regulate the organization of DNA and are important targets for many clinically used antineoplastic agents. In addition, DNA topoisomerases modulate the cellular sensitivity toward a number of DNA damaging agents. Increased topoisomerase II activities were shown to contribute to the resistance of both nitrogen mustard- and cisplatin-resistant cells. Similarly, cells with decreased topoisomerase II levels show increased sensitivity to cisplatin, carmustine, mitomycin C and nitrogen mustard. Recent studies propose that topoisomerases may be involved in damage recognition and DNA repair at several different levels including: 1) the initial recognition of DNA lesions; 2) DNA recombination; and 3) regulation of DNA structure. The stress-activated oncogene suppressor protein p53 can modulate the activity of at least three different human topoisomerases, either directly by molecular associations or by transcriptional regulation. Since DNA topoisomerases have considerable recombinase activities, inappropriately activated topoisomerases in tumor cells lacking functional p53 may contribute to the genetic instability of these cells.

bimA encodes a member of the tetratricopeptide repeat family of proteins and is required for the completion of mitosis in Aspergillus nidulans

1991 ◽  
Vol 99 (4) ◽  
pp. 711-719
Author(s):  
K.L. O'Donnell ◽  
A.H. Osmani ◽  
S.A. Osmani ◽  
N.R. Morris
Keyword(s):  
Amino Acid ◽  
Aspergillus Nidulans ◽  
Essential Gene ◽  
Tetratricopeptide Repeat ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Amino Acid Residues ◽  
Wild Type ◽  
Reading Frame ◽  
Integrative Transformation

The recessive, temperature-sensitive bimA1 mutation of Aspergillus nidulans blocks nuclei in metaphase at restrictive temperature. To determine whether the bimA product is essential, integrative transformation was used to create a mutation in the bimA gene. The mutation was maintained in a heterokaryon and the phenotype of spores produced by the heterokaryon was analyzed. Molecular disruption of the wild-type bimA gene is recessive in the heterokaryon and causes a metaphase block, demonstrating that bimA is an essential gene for mitosis. bimA was cloned by DNA-mediated complementation of its mutant phenotype at restrictive temperature, and the nucleotide sequence of a full-length cDNA was determined. A single large open reading frame was identified in the cDNA sequence, which predicts a protein containing 806 amino acid residues that is related (30.4% identity) to the Schizosaccharomyces pombe nuc2+ gene product, which also is required for completion of mitosis. The sequence of the bimA gene indicates that it is a member of a family of mostly nuclear proteins that contain a degenerate 34 amino acid repeat, the TPR (tetratricopeptide repeat) gene family.

scholarly journals The Relationship between Frailty Syndrome and Concerns about an Implantable Cardioverter Defibrillator

2020 ◽  
Vol 17 (6) ◽  
pp. 1954
Author(s):  
Agnieszka Mlynarska ◽  
Rafal Mlynarski ◽  
Izabella Uchmanowicz ◽  
Czeslaw Marcisz ◽  
Krzysztof S. Golba
Keyword(s):  
Implantable Cardioverter Defibrillator ◽  
Frailty Syndrome ◽  
Icd Implantation ◽  
Cardioverter Defibrillator ◽  
Questionnaire Score ◽  
Tilburg Frailty Indicator ◽  
Increased Sensitivity ◽  
The Impact ◽  
The Relationship ◽  
Frailty Indicator

Frailty syndrome may cause cognitive decline and increased sensitivity to stressors. This can result in an increased incidence of anxiety and depression, and thus, concerns about life with an implantable cardioverter defibrillator (ICD). The aim of the study was to assess the impact of frailty syndrome on the increase in the number of device-related concerns after the implantation of an ICD. Material and methods: The study sample was a group of 103 consecutive patients (85 M; aged 71.6 ± 8.2) with an implanted ICD. The ICD Concerns Questionnaire (ICDC) was used to analyze their concerns about life with an ICD, and the Tilburg Frailty Indicator scale (TFI) was used to diagnose frailty. Results: In the group of patients with an ICD implanted, 73% had recognized frailty (83.3% women, 74.1% men); the average point value was 6.55 ± 2.67. The total ICDC questionnaire score for the patients with an implanted cardioverter defibrillator was 34.06 ± 18.15. Patients with frailty syndrome had statistically (p = 0.039) higher scores (36.14 ± 17.08) compared to robust patients (27.56 ± 20.13). In the logistic regression analysis, the presence of frailty was strongly associated with the total questionnaire score (OR = 1.0265, p = 0.00426), the severity of the concerns (OR = 1.0417, p = 0.00451), and device-specific concerns (OR = 1.0982, p = 0.00424). Conclusion: Frailty syndrome occurs in about 80% of patients after ICD implantation. The presence of frailty syndrome was strongly associated with concerns about an implantable cardioverter defibrillator.

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