scholarly journals Survival of, and competition between, oligodendrocytes expressing different alleles of the Plp gene

2002 ◽  
Vol 158 (4) ◽  
pp. 719-729 ◽  
Author(s):  
J.M. Edgar ◽  
T.J. Anderson ◽  
P.J. Dickinson ◽  
J.A. Barrie ◽  
M.C. McCulloch ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Survival ◽  
Mutant Allele ◽  
Null Allele ◽  
Compound Heterozygote ◽  
Null Alleles ◽  
Stable Population ◽  
Intrinsic Factors ◽  
Compound Heterozygotes

Mutations in the X-linked Plp gene lead to dysmyelinating phenotypes and oligodendrocyte cell death. Here, we exploit the X inactivation phenomenon to show that a hierarchy exists in the influence of different mutant Plp alleles on oligodendrocyte survival. We used compound heterozygote mice to study the long-term fate of oligodendrocytes expressing either the jimpy or rumpshaker allele against a background of cells expressing a Plp-null allele. Although mutant and null oligodendrocytes were generated in equal numbers, the proportion expressing the mutant allele subsequently declined, but whereas those expressing the rumpshaker allele formed a reduced but stable population, the number of jimpy cells fell progressively. The age of decline in the jimpy cells in different regions of the CNS correlated with the temporal sequence of myelination. In compound heterozygotes expressing rumpshaker and jimpy alleles, oligodendrocytes expressing the former predominated and were more abundant than when the rumpshaker and null alleles were in competition. Thus, oligodendrocyte survival is not determined solely by cell intrinsic factors, such as the conformation of the misfolded PLP, but is influenced by neighboring cells, possibly competing for cell survival factors.

Defects in heart and lung development in compound heterozygotes for two different targeted mutations at the N-myc locus

Development ◽  
1993 ◽  
Vol 119 (2) ◽  
pp. 485-499 ◽  
Author(s):  
C.B. Moens ◽  
B.R. Stanton ◽  
L.F. Parada ◽  
J. Rossant
Keyword(s):  
Lung Development ◽  
Mutant Allele ◽  
Null Allele ◽  
Embryonic Stem ◽  
Branching Morphogenesis ◽  
Compound Heterozygote ◽  
Compact Layer ◽  
Subepicardial Layer ◽  
The Times ◽  
Compound Heterozygotes

Two types of mutant allele, one leaky and one null, have been generated by gene targeting at the N-myc locus in embryonic stem cells and the phenotypes of mice homozygous for these mutations have been described. These mutations have shown that N-myc has a number of functions during development, including a role in branching morphogenesis in the lung, which manifests itself at birth in mice homozygous for the leaky allele, and roles in the development of the mesonephric tubules, the neuroepithelium, the sensory ganglia, the gut and the heart, which become evident at midgestation in embryos homozygous for the null allele. In an attempt to define roles for N-myc at other stages of development, we have combined the two types of N-myc mutant allele in a compound heterozygote that as a result contains approximately 15% of normal levels of N-Myc protein. Compound heterozygotes died during gestation at a time intermediate to the times of death of embryos homozygous for either mutation individually, and their death appeared to result from cardiac failure stemming from hypoplasia of the compact subepicardial layer of the myocardium. Investigation of the expression pattern of N-myc and various markers of differentiation in wild-type and compound heterozygote mutant hearts has suggested that N-myc may function in maintaining the proliferation and/or preventing the differentiation of compact layer myocytes. This study illustrates the importance of generating different mutations at a given locus to elucidate fully the function of a particular gene during development.

scholarly journals Polyploidy and Mitotic Cell Death Are Two Distinct HIV-1 Vpr-Driven Outcomes in Renal Tubule Epithelial Cells

2017 ◽  
Vol 92 (2) ◽  
Author(s):  
Emily H. Payne ◽  
Dhivya Ramalingam ◽  
Donald T. Fox ◽  
Mary E. Klotman
Keyword(s):  
Cell Cycle ◽  
Cell Death ◽  
Epithelial Cells ◽  
Cell Survival ◽  
Renal Cell ◽  
Cell Biology ◽  
Renal Tubule ◽  
Mitotic Cell ◽  
Hiv Positive

ABSTRACTPrior studies have found that HIV, through the Vpr protein, promotes genome reduplication (polyploidy) in infection-surviving epithelial cells within renal tissue. However, the temporal progression and molecular regulation through which Vpr promotes polyploidy have remained unclear. Here we define a sequential progression to Vpr-mediated polyploidy in human renal tubule epithelial cells (RTECs). We found that as in many cell types, Vpr first initiates G2cell cycle arrest in RTECs. We then identified a previously unreported cascade of Vpr-dependent events that lead to renal cell survival and polyploidy. Specifically, we found that a fraction of G2-arrested RTECs reenter the cell cycle. Following this cell cycle reentry, two distinct outcomes occur. Cells that enter complete mitosis undergo mitotic cell death due to extra centrosomes and aberrant division. Conversely, cells that abort mitosis undergo endoreplication to become polyploid. We further show that multiple small-molecule inhibitors of the phosphatidylinositol 3-kinase-related kinase (PIKK) family, including those that target ATR, ATM, and mTOR, indirectly prevent Vpr-mediated polyploidy by preventing G2arrest. In contrast, an inhibitor that targets DNA-dependent protein kinase (DNA-PK) specifically blocks the Vpr-mediated transition from G2arrest to polyploidy. These findings outline a temporal, molecularly regulated path to polyploidy in HIV-positive renal cells.IMPORTANCECurrent cure-focused efforts in HIV research aim to elucidate the mechanisms of long-term persistence of HIV in compartments. The kidney is recognized as one such compartment, since viral DNA and mRNA persist in the renal tissues of HIV-positive patients. Further, renal disease is a long-term comorbidity in the setting of HIV. Thus, understanding the regulation and impact of HIV infection on renal cell biology will provide important insights into this unique HIV compartment. Our work identifies mechanisms that distinguish between HIV-positive cell survival and death in a known HIV compartment, as well as pharmacological agents that alter these outcomes.

scholarly journals Collagen (I) homotrimer does not cause bone fragility but potentiates the osteogenesis imperfecta (oim) mutant allele

2020 ◽  
Author(s):  
Katie J. Lee ◽  
Lisa Rambault ◽  
George Bou-Gharios ◽  
Peter D. Clegg ◽  
Riaz Akhtar ◽  
...  
Keyword(s):  
Osteogenesis Imperfecta ◽  
Structural Properties ◽  
Mutant Allele ◽  
Bone Fragility ◽  
Null Alleles ◽  
Type I ◽  
Male Mice ◽  
Allelic Discrimination ◽  
Bone Phenotype ◽  
Compound Heterozygotes

AbstractType I collagen is the major structural component of bone where it exists as an (α1)2(α2)1 heterotrimer in all vertebrates. The oim mouse model comprising solely homotrimeric (α1)3 collagen–1, due to a dysfunctional α2 chain, has a brittle bone phenotype implying that the heterotrimeric form is required for physiological bone function. However, humans with null alleles preventing synthesis of the α2 chain have connective tissue and cardiovascular abnormalities (cardiac valvular Ehlers Danlos Syndrome), without evident bone fragility. Col1a2 null and osteogenesis imperfecta (oim) mouse lines were used in this study and bones analysed by microCT and 3–point bending. RNA was also extracted from heterozygote tissues and allelic discrimination analyses performed using qRT–PCR. Here we show that mice lacking the α2(I) chain do not have impaired biomechanical or bone structural properties, unlike oim homozygous mice. However Mendelian inheritance was affected in male mice of both lines and male mice null for the α2 chain exhibited age–related loss of condition. The brittle bone phenotype of oim homozygotes could result from detrimental effects of the oim mutant allele, however the phenotype of oim heterozygotes is known to be less severe. We used allelic discrimination to show that the oim mutant allele is not downregulated in heterozygotes. We then tested whether gene dosage was responsible for the less severe phenotype of oim heterozygotes by generating compound heterozygotes. Data showed that compound heterozygotes had impaired bone structural properties as compared to oim heterozygotes, albeit to a lesser extent than oim homozygotes. Hence, we concluded that the presence of heterotrimeric collagen–1 in oim heterozygotes alleviates the effect of the oim mutant allele but a genetic interaction between homotrimeric collagen–1 and the oim mutant allele leads to bone fragility.

scholarly journals Induction of Autophagy during Extracellular Matrix Detachment Promotes Cell Survival

2008 ◽  
Vol 19 (3) ◽  
pp. 797-806 ◽  
Author(s):  
Christopher Fung ◽  
Rebecca Lock ◽  
Sizhen Gao ◽  
Eduardo Salas ◽  
Jayanta Debnath
Keyword(s):  
Extracellular Matrix ◽  
Cell Death ◽  
Cell Survival ◽  
Three Dimensional ◽  
Clonogenic Survival ◽  
Mammary Epithelial ◽  
Lumen Formation ◽  
Stable Reduction ◽  
Promote Cell Death

Autophagy has been proposed to promote cell death during lumen formation in three-dimensional mammary epithelial acini because numerous autophagic vacuoles are observed in the dying central cells during morphogenesis. Because these central cells die due to extracellular matrix (ECM) deprivation (anoikis), we have directly interrogated how matrix detachment regulates autophagy. Detachment induces autophagy in both nontumorigenic epithelial lines and in primary epithelial cells. RNA interference-mediated depletion of autophagy regulators (ATGs) inhibits detachment-induced autophagy, enhances apoptosis, and reduces clonogenic recovery after anoikis. Remarkably, matrix-detached cells still exhibit autophagy when apoptosis is blocked by Bcl-2 overexpression, and ATG depletion reduces the clonogenic survival of Bcl-2–expressing cells after detachment. Finally, stable reduction of ATG5 or ATG7 in MCF-10A acini enhances luminal apoptosis during morphogenesis and fails to elicit long-term luminal filling, even when combined with apoptotic inhibition mediated by Bcl-2 overexpression. Thus, autophagy promotes epithelial cell survival during anoikis, including detached cells harboring antiapoptotic lesions.

Neuroglobin and Estrogen Receptors: A New Pathway of Cell Survival and Cell Death Balance

2015 ◽  
Vol 14 (2) ◽  
pp. 91-99 ◽  
Author(s):  
Maria T. Nuzzo ◽  
Marco Fiocchetti ◽  
Paolo Ascenzi ◽  
Maria Marino
Keyword(s):  
Cell Death ◽  
Estrogen Receptors ◽  
Cell Survival

scholarly journals Long-Term Exposure to Nanosized TiO2 Triggers Stress Responses and Cell Death Pathways in Pulmonary Epithelial Cells

2021 ◽  
Vol 22 (10) ◽  
pp. 5349
Author(s):  
Mayes Alswady-Hoff ◽  
Johanna Samulin Erdem ◽  
Santosh Phuyal ◽  
Oskar Knittelfelder ◽  
Animesh Sharma ◽  
...  
Keyword(s):  
Cell Death ◽  
Epithelial Cells ◽  
Health Effects ◽  
Stress Responses ◽  
Cell Stress ◽  
Lipid Classes ◽  
Long Term Effects ◽  
Cell Death Pathways ◽  
Pulmonary Epithelial Cells

There is little in vitro data available on long-term effects of TiO2 exposure. Such data are important for improving the understanding of underlying mechanisms of adverse health effects of TiO2. Here, we exposed pulmonary epithelial cells to two doses (0.96 and 1.92 µg/cm2) of TiO2 for 13 weeks and effects on cell cycle and cell death mechanisms, i.e., apoptosis and autophagy were determined after 4, 8 and 13 weeks of exposure. Changes in telomere length, cellular protein levels and lipid classes were also analyzed at 13 weeks of exposure. We observed that the TiO2 exposure increased the fraction of cells in G1-phase and reduced the fraction of cells in G2-phase, which was accompanied by an increase in the fraction of late apoptotic/necrotic cells. This corresponded with an induced expression of key apoptotic proteins i.e., BAD and BAX, and an accumulation of several lipid classes involved in cellular stress and apoptosis. These findings were further supported by quantitative proteome profiling data showing an increase in proteins involved in cell stress and genomic maintenance pathways following TiO2 exposure. Altogether, we suggest that cell stress response and cell death pathways may be important molecular events in long-term health effects of TiO2.

scholarly journals LONP1 and ClpP cooperatively regulate mitochondrial proteostasis for cancer cell survival

Oncogenesis ◽  
2021 ◽  
Vol 10 (2) ◽  
Author(s):  
Yu Geon Lee ◽  
Hui Won Kim ◽  
Yeji Nam ◽  
Kyeong Jin Shin ◽  
Yu Jin Lee ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Growth ◽  
Cell Survival ◽  
Cancer Cell ◽  
Stress Responses ◽  
Molecular Mechanisms ◽  
Tca Cycle ◽  
Mitochondrial Matrix ◽  
Mitochondrial Functions ◽  
Cancer Cell Survival

AbstractMitochondrial proteases are key components in mitochondrial stress responses that maintain proteostasis and mitochondrial integrity in harsh environmental conditions, which leads to the acquisition of aggressive phenotypes, including chemoresistance and metastasis. However, the molecular mechanisms and exact role of mitochondrial proteases in cancer remain largely unexplored. Here, we identified functional crosstalk between LONP1 and ClpP, which are two mitochondrial matrix proteases that cooperate to attenuate proteotoxic stress and protect mitochondrial functions for cancer cell survival. LONP1 and ClpP genes closely localized on chromosome 19 and were co-expressed at high levels in most human cancers. Depletion of both genes synergistically attenuated cancer cell growth and induced cell death due to impaired mitochondrial functions and increased oxidative stress. Using mitochondrial matrix proteomic analysis with an engineered peroxidase (APEX)-mediated proximity biotinylation method, we identified the specific target substrates of these proteases, which were crucial components of mitochondrial functions, including oxidative phosphorylation, the TCA cycle, and amino acid and lipid metabolism. Furthermore, we found that LONP1 and ClpP shared many substrates, including serine hydroxymethyltransferase 2 (SHMT2). Inhibition of both LONP1 and ClpP additively increased the amount of unfolded SHMT2 protein and enhanced sensitivity to SHMT2 inhibitor, resulting in significantly reduced cell growth and increased cell death under metabolic stress. Additionally, prostate cancer patients with higher LONP1 and ClpP expression exhibited poorer survival. These results suggest that interventions targeting the mitochondrial proteostasis network via LONP1 and ClpP could be potential therapeutic strategies for cancer.

scholarly journals Co-delivery of IOX1 and doxorubicin for antibody-independent cancer chemo-immunotherapy

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jing Liu ◽  
Zhihao Zhao ◽  
Nasha Qiu ◽  
Quan Zhou ◽  
Guowei Wang ◽  
...  
Keyword(s):  
Cell Death ◽  
T Cell ◽  
Programmed Cell Death ◽  
Memory Function ◽  
Histone Demethylase ◽  
Cell Dysfunction ◽  
T Cell Infiltration ◽  
Programmed Cell Death 1 ◽  
T Cell Dysfunction

AbstractAnti-programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) antibodies are currently used in the clinic to interupt the PD-1/PD-L1 immune checkpoint, which reverses T cell dysfunction/exhaustion and shows success in treating cancer. Here, we report a histone demethylase inhibitor, 5-carboxy-8-hydroxyquinoline (IOX1), which inhibits tumour histone demethylase Jumonji domain-containing 1A (JMJD1A) and thus downregulates its downstream β-catenin and subsequent PD-L1, providing an antibody-independent paradigm interrupting the PD-1/PD-L1 checkpoint. Synergistically, IOX1 inhibits cancer cells’ P-glycoproteins (P-gp) through the JMJD1A/β-catenin/P-gp pathway and greatly enhances doxorubicin (DOX)-induced immune-stimulatory immunogenic cell death. As a result, the IOX1 and DOX combination greatly promotes T cell infiltration and activity and significantly reduces tumour immunosuppressive factors. Their liposomal combination reduces the growth of various murine tumours, including subcutaneous, orthotopic, and lung metastasis tumours, and offers a long-term immunological memory function against tumour rechallenging. This work provides a small molecule-based potent cancer chemo-immunotherapy.

scholarly journals A Screen for Mutations That Suppress the Phenotype of Drosophila armadillo, the β-Catenin Homolog

Genetics ◽  
2000 ◽  
Vol 155 (4) ◽  
pp. 1725-1740
Author(s):  
Rachel T Cox ◽  
Donald G McEwen ◽  
Denise L Myster ◽  
Robert J Duronio ◽  
Joseph Loureiro ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Adhesion ◽  
Programmed Cell Death ◽  
Cell Survival ◽  
Wnt Pathway ◽  
Genetic Modifier ◽  
Wnt Signaling Pathway ◽  
Adherens Junction ◽  
Cell Fates ◽  
Wnt Signal

Abstract During development signaling pathways coordinate cell fates and regulate the choice between cell survival or programmed cell death. The well-conserved Wingless/Wnt pathway is required for many developmental decisions in all animals. One transducer of the Wingless/Wnt signal is Armadillo/β-catenin. Drosophila Armadillo not only transduces Wingless signal, but also acts in cell-cell adhesion via its role in the epithelial adherens junction. While many components of both the Wingless/Wnt signaling pathway and adherens junctions are known, both processes are complex, suggesting that unknown components influence signaling and junctions. We carried out a genetic modifier screen to identify some of these components by screening for mutations that can suppress the armadillo mutant phenotype. We identified 12 regions of the genome that have this property. From these regions and from additional candidate genes tested we identified four genes that suppress arm: dTCF, puckered, head involution defective (hid), and Dpresenilin. We further investigated the interaction with hid, a known regulator of programmed cell death. Our data suggest that Wg signaling modulates Hid activity and that Hid regulates programmed cell death in a dose-sensitive fashion.

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