scholarly journals Role of Ethylene on de Novo Shoot Regeneration from Cotyledonary Explants of Brassica campestris ssp. pekinensis (Lour) Olsson in Vitro

1991 ◽  
Vol 96 (1) ◽  
pp. 178-183 ◽  
Author(s):  
Gek-Lan Chi ◽  
Eng-Chong Pua ◽  
Chong-Jin Goh
Keyword(s):  
Shoot Regeneration ◽  
Brassica Campestris ◽  
De Novo ◽  
Cotyledonary Explants

scholarly journals Differences in the Manifestation of Cell Pluripotence In Vivo and In Vitro in the Mutant Arabidopsis thaliana with the Phenotype of Cell Memory Disorder

2021 ◽  
Vol 68 (1) ◽  
pp. 46-55
Author(s):  
E. V. Kupriyanova ◽  
E. R. Denisova ◽  
M. A. Baier ◽  
T. A. Ezhova
Keyword(s):  
Arabidopsis Thaliana ◽  
Shoot Regeneration ◽  
Cultured Cells ◽  
De Novo ◽  
Epigenetic Memory ◽  
In Planta ◽  
Pluripotency Genes

Abstract Plant cells cultivated in vitro are a convenient model for studying the genetic and physiological mechanisms necessary for the cells to acquire a state of pluripotency. Earlier studies on a model plant Arabidopsis thaliana (L.) Heynh. have identified the key role of genes that determine the pluripotency of cells in the shoot apical meristem in de novo shoot regeneration in tissue culture. In accordance with this, cells of mutant plants with a higher level of expression of pluripotency genes were characterized by an increased potential for de novo shoot regeneration. The tae mutant was the exception to this rule. The mutant resumed the expression of pluripotency genes and cell proliferation at the late stages of leaf development, which indicates a violation of the mechanisms for maintaining epigenetic cellular memory. At the same time, leaf cells cultured in vitro showed a lower proliferative activity compared to the wild type and were not capable of de novo regeneration of shoots. A decrease in the regenerative potential of cultured cells of the tae mutant indicates an important role of epigenetic memory in the response of cells to exogenous hormones. Impaired epigenetic memory of leaf cells of the tae mutant and differences in their proliferative and regenerative capacities in planta and in vitro make this mutant a unique model for studying the role of epigenetic modifications in the regulation of cell pluripotency.

scholarly journals Cytoplasmic Expression of the ALS/FTD-Related Protein TDP-43 Decreases Global Translation Both in vitro and in vivo

2020 ◽  
Vol 14 ◽  
Author(s):  
Santiago E. Charif ◽  
Luciana Luchelli ◽  
Antonella Vila ◽  
Matías Blaustein ◽  
Lionel M. Igaz
Keyword(s):  
De Novo ◽  
Brain Slices ◽  
Mrna Translation ◽  
Hek293 Cells ◽  
Cytoplasmic Inclusions ◽  
Cytoplasmic Expression ◽  
Global Translation

TDP-43 is a major component of cytoplasmic inclusions observed in neurodegenerative diseases like frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). To further understand the role of TDP-43 in mRNA/protein metabolism and proteostasis, we used a combined approach with cellular and animal models overexpressing a cytoplasmic form of human TDP-43 (TDP-43-ΔNLS), recapitulating ALS/FTD features. We applied in HEK293 cells a method for labeling de novo translation, surface sensing of translation (SUnSET), based on puromycin (PURO) incorporation. While control cells displayed robust puromycilation, TDP-43-ΔNLS transfected cells exhibited reduced ongoing protein synthesis. Next, by using a transgenic mouse overexpressing cytoplasmic TDP-43 in the forebrain (TDP-43-ΔNLS mice) we assessed whether cytoplasmic TDP-43 regulates global translation in vivo. Polysome profiling of brain cortices from transgenic mice showed a shift toward non-polysomal fractions as compared to wild-type littermates, indicating a decrease in global translation. Lastly, cellular level translational assessment by SUNSET was performed in TDP-43-ΔNLS mice brain slices. Control mice slices incubated with PURO exhibited robust cytoplasmic PURO signal in layer 5 neurons from motor cortex, and normal nuclear TDP-43 staining. Neurons in TDP-43-ΔNLS mice slices incubated with PURO exhibited high cytoplasmic expression of TDP-43 and reduced puromycilation respect to control mice. These in vitro and in vivo results indicate that cytoplasmic TDP-43 decreases global translation and potentially cause functional/cytotoxic effects as observed in ALS/FTD. Our study provide in vivo evidence (by two independent and complementary methods) for a role of mislocalized TDP-43 in the regulation of global mRNA translation, with implications for TDP-43 proteinopathies.

scholarly journals NAD+-Dependent Deacetylase Hst1p Controls Biosynthesis and Cellular NAD+ Levels in Saccharomyces cerevisiae

2003 ◽  
Vol 23 (19) ◽  
pp. 7044-7054 ◽  
Author(s):  
Antonio Bedalov ◽  
Maki Hirao ◽  
Jeffrey Posakony ◽  
Melisa Nelson ◽  
Julian A. Simon
Keyword(s):  
De Novo ◽  
Critical Role ◽  
Salvage Pathway ◽  
De Novo Synthesis ◽  
Array Analysis ◽  
Binding Partner ◽  
Dependent Protein ◽  
New Protein

ABSTRACT Nicotine adenine dinucleotide (NAD+) performs key roles in electron transport reactions, as a substrate for poly(ADP-ribose) polymerase and NAD+-dependent protein deacetylases. In the latter two processes, NAD+ is consumed and converted to ADP-ribose and nicotinamide. NAD+ levels can be maintained by regeneration of NAD+ from nicotinamide via a salvage pathway or by de novo synthesis of NAD+ from tryptophan. Both pathways are conserved from yeast to humans. We describe a critical role of the NAD+-dependent deacetylase Hst1p as a sensor of NAD+ levels and regulator of NAD+ biosynthesis. Using transcript arrays, we show that low NAD+ states specifically induce the de novo NAD+ biosynthesis genes while the genes in the salvage pathway remain unaffected. The NAD+-dependent deacetylase activity of Hst1p represses de novo NAD+ biosynthesis genes in the absence of new protein synthesis, suggesting a direct effect. The known Hst1p binding partner, Sum1p, is present at promoters of highly inducible NAD+ biosynthesis genes. The removal of HST1-mediated repression of the NAD+ de novo biosynthesis pathway leads to increased cellular NAD+ levels. Transcript array analysis shows that reduction in cellular NAD+ levels preferentially affects Hst1p-regulated genes in comparison to genes regulated with other NAD+-dependent deacetylases (Sir2p, Hst2p, Hst3p, and Hst4p). In vitro experiments demonstrate that Hst1p has relatively low affinity toward NAD+ in comparison to other NAD+-dependent enzymes. These findings suggest that Hst1p serves as a cellular NAD+ sensor that monitors and regulates cellular NAD+ levels.

ROLE OF THE MESENCHYME IN THE INDUCTION OF THE RAT PROSTATE GLAND BY ANDROGENS IN ORGAN CULTURE

1979 ◽  
Vol 82 (1) ◽  
pp. 171-NP ◽  
Author(s):  
ILSE LASNITZKI ◽  
TAKEO MIZUNO
Keyword(s):  
Organ Culture ◽  
De Novo ◽  
Prostate Gland ◽  
Young Male ◽  
Free Medium ◽  
Foetal Rat ◽  
Rat Prostate ◽  
Do So

SUMMARY Rat prostate glands are induced de novo by androgens in 16·5-day-old male and female urogenital sinuses in vitro as epithelial buds projecting into the surrounding mesenchyme. The role of the mesenchyme in this process has been investigated in various epithelial-mesenchymal recombinations in organ culture. Isolated epithelium did not form buds but required the presence of the mesenchyme to do so. This requirement seemed to be specific; in the presence of testosterone or dihydrotestosterone only urogenital mesenchyme increased cell division in the urogenital epithelium and stimulated prostatic bud formation. In contrast, heterotypic mesenchyme did not affect epithelial mitosis and failed to induce buds while heterotypic epithelia did not respond to urogenital mesenchyme. In recombinants of urogenital mesenchyme pretreated with androgen and untreated urogenital epithelium, grown in androgen-free medium, the majority of explants developed prostatic buds while only a few buds were formed from epithelium pretreated with androgen when it was recombined with untreated mesenchyme. The role of the mesenchyme in the loss of androgen responsiveness of the older female sinuses was examined in heterochronic recombinants. It was found that the old female mesenchyme failed to induce buds in young epithelium while young male or female mesenchymes induced them in the old female epithelium. The results suggest that the urogenital mesenchyme is essential for the initiation of the foetal rat prostate gland and that it may be a target for androgens and complement or mediate their effect on the epithelium.

The Role of Nucleophosmin In Hematopoietic Stem Cells and the Pathogenesis of Myelodysplastic Syndrome

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 95-95 ◽  
Author(s):  
Keisuke Ito ◽  
Paolo Sportoletti ◽  
John G Clohessy ◽  
Grisendi Silvia ◽  
Pier Paolo Pandolfi
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Myelodysplastic Syndrome ◽  
Cell Biology ◽  
De Novo ◽  
Stem Cell Biology ◽  
Hematopoietic Stem

Abstract Abstract 95 Myelodysplastic syndrome (MDS) is an incurable stem cell disorder characterized by ineffective hematopoiesis and an increased risk of leukemia transformation. Nucleophosmin (NPM) is directly implicated in primitive hematopoiesis, the pathogenesis of hematopoietic malignancies and more recently of MDS. However, little is known regarding the molecular role and function of NPM in MDS pathogenesis and in stem cell biology. Here we present data demonstrating that NPM plays a critical role in the maintenance of hematopoietic stem cells (HSCs) and the transformation of MDS into leukemia. NPM is located on chromosome 5q and is frequently lost in therapy-related and de novo MDS. We have previously shown that Npm1 acts as a haploinsufficient tumor suppressor in the hematopoietic compartment and Npm1+/− mice develop a hematologic syndrome with features of human MDS, including increased susceptibility to leukemogenesis. As HSCs have been demonstrated to be the target of the primary neoplastic event in MDS, a functional analysis of the HSC compartment is essential to understand the molecular mechanisms in MDS pathogenesis. However, the role of NPM in adult hematopoiesis remains largely unknown as Npm1-deficiency leads to embryonic lethality. To investigate NPM function in adult hematopoiesis, we have generated conditional knockout mice of Npm1, using the Cre-loxP system. Analysis of Npm1 conditional mutants crossed with Mx1-Cre transgenic mice reveals that Npm1 plays a crucial role in adult hematopoiesis and ablation of Npm1 in adult HSCs leads to aberrant cycling and followed by apoptosis. Analysis of cell cycle status revealed that HSCs are impaired in their ability to maintain quiescence after Npm1-deletion and are rapidly depleted in vivo as well as in vitro. Competitive reconstitution assay revealed that Npm1 acts cell-autonomously to maintain HSCs. Conditional inactivation of Npm1 leads to an MDS phenotype including a profoundly impaired ability to differentiate into cells of the erythroid lineage, megakaryocyte dyspoiesis and centrosome amplification. Furthermore, Npm1 loss evokes a p53-dependent response and Npm1-deleted HSCs undergo apoptosis in vivo and in vitro. Strikingly, transfer of the Npm1 mutation into a p53-null background rescued the apoptosis of Npm1-ablated HSCs and resulted in accelerated transformation to an aggressive and lethal form of acute myeloid leukemia. Our findings highlight the crucial role of NPM in stem cell biology and identify a new mechanism by which MDS can progress to leukemia. This has important therapeutic implications for de novo MDS as well as therapy-related MDS, which is known to rapidly evolve to leukemia with frequent loss or mutation of TRP53. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Inhibiting adenine synthesis attenuates glioblastoma cell stemness and temozolomide resistance

2021 ◽  
Author(s):  
Simranjit X. Singh ◽  
Rui Yang ◽  
Kristen Roso ◽  
Landon J. Hansen ◽  
Changzheng Du ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Mitochondrial Function ◽  
Brain Cancer ◽  
De Novo ◽  
Critical Role ◽  
Glioblastoma Cell ◽  
Respiratory Capacity ◽  
Complementary Approach

Glioblastoma (GBM) is a lethal brain cancer exhibiting high levels of drug resistance, a feature partially imparted by tumor cell stemness. Recent work shows that homozygous MTAP deletion, a genetic alteration occurring in about half of all GBMs, promotes stemness in GBM cells. Exploiting MTAP loss-conferred deficiency in adenine salvage, we demonstrate that transient adenine blockade via treatment with L-Alanosine (ALA), an inhibitor of de novo adenine synthesis, attenuates stemness of MTAP-deficient GBM cells. This ALA-induced reduction in stemness is accompanied by compromised mitochondrial function, highlighted by diminished spare respiratory capacity. Direct pharmacological inhibition of mitochondrial respiration recapitulates the effect of ALA on GBM cell stemness, suggesting ALA targets stemness partially via affecting mitochondrial function. Finally, in agreement with diminished stemness and compromised mitochondrial function, we show that ALA sensitizes GBM cells to temozolomide (TMZ) in vitro and in an orthotopic GBM model. Collectively, these results identify critical roles of adenine supply in maintaining mitochondrial function and stemness of GBM cells, highlight a critical role of mitochondrial function in sustaining GBM stemness, and implicate adenine synthesis inhibition as a complementary approach for treating MTAP-deleted GBMs.

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