Defective cell proliferation is an attribute of overexpressed Notch1 receptor and impaired autophagy in Fanconi Anemia

Genomics ◽  
2020 ◽  
Vol 112 (6) ◽  
pp. 4628-4639
Author(s):  
Binita Zipporah E ◽  
Bamadeb Patra ◽  
Kavitha Govarthanan ◽  
Rajesh Yadav ◽  
Sheila Mohan ◽  
...  
2007 ◽  
Vol 176 (5) ◽  
pp. 695-707 ◽  
Author(s):  
Hideki Niimi ◽  
Katerina Pardali ◽  
Michael Vanlandewijck ◽  
Carl-Henrik Heldin ◽  
Aristidis Moustakas

Transforming growth factor β (TGF-β) and Notch act as tumor suppressors by inhibiting epithelial cell proliferation. TGF-β additionally promotes tumor invasiveness and metastasis, whereas Notch supports oncogenic growth. We demonstrate that TGF-β and ectopic Notch1 receptor cooperatively arrest epithelial growth, whereas endogenous Notch signaling was found to be required for TGF-β to elicit cytostasis. Transcriptomic analysis after blocking endogenous Notch signaling uncovered several genes, including Notch pathway components and cell cycle and apoptosis factors, whose regulation by TGF-β requires an active Notch pathway. A prominent gene coregulated by the two pathways is the cell cycle inhibitor p21. Both transcriptional induction of the Notch ligand Jagged1 by TGF-β and endogenous levels of the Notch effector CSL contribute to p21 induction and epithelial cytostasis. Cooperative inhibition of cell proliferation by TGF-β and Notch is lost in human mammary cells in which the p21 gene has been knocked out. We establish an intimate involvement of Notch signaling in the epithelial cytostatic response to TGF-β.


2020 ◽  
Vol 117 (52) ◽  
pp. 33436-33445
Author(s):  
Rui Wang ◽  
Walter F. Lenoir ◽  
Chao Wang ◽  
Dan Su ◽  
Megan McLaughlin ◽  
...  

Fanconi anemia (FA) is caused by defects in cellular responses to DNA crosslinking damage and replication stress. Given the constant occurrence of endogenous DNA damage and replication fork stress, it is unclear why complete deletion of FA genes does not have a major impact on cell proliferation and germ-line FA patients are able to progress through development well into their adulthood. To identify potential cellular mechanisms that compensate for the FA deficiency, we performed dropout screens in FA mutant cells with a whole genome guide RNA library. This uncovered a comprehensive genome-wide profile of FA pathway synthetic lethality, including POLI and CDK4. As little is known of the cellular function of DNA polymerase iota (Pol ι), we focused on its role in the loss-of-function FA knockout mutants. Loss of both FA pathway function and Pol ι leads to synthetic defects in cell proliferation and cell survival, and an increase in DNA damage accumulation. Furthermore, FA-deficient cells depend on the function of Pol ι to resume replication upon replication fork stalling. Our results reveal a critical role for Pol ι in DNA repair and replication fork restart and suggest Pol ι as a target for therapeutic intervention in malignancies carrying an FA gene mutation.


Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2949-2949
Author(s):  
Qingshuo Zhang ◽  
Eric Benedetti ◽  
Matthew Deater ◽  
Kathryn Schubert ◽  
Angela Major ◽  
...  

Abstract Androgens are widely used for treating Fanconi anemia and other human bone marrow failure syndromes, but their mode of action remains incompletely understood. Aged Fancd2-/- mice were used to assess the therapeutic efficacy of oxymetholone and its mechanism of action. 18-month old Fancd2-/- mice recapitulated key human Fanconi anemia phenotypes including reduced bone marrow cellularity, red cell macrocytosis, and peripheral pancytopenia. As in humans, chronic oxymetholone treatment significantly improved these hematological parameters by stimulating the proliferation of hematopoietic stem and progenitor cells. RNAseq analysis implicated down-regulation of osteopontin as an important mechanism for the drug’s action. Consistent with the increased stem cell proliferation, competitive repopulation assays demonstrated that chronic oxymetholone therapy eventually resulted in stem cell exhaustion. These results expand our knowledge of the regulation of hematopoietic stem cell proliferation and have direct clinical implications for the treatment of bone marrow failure. Disclosures No relevant conflicts of interest to declare.


Author(s):  
C. W. Kischer

The morphology of the fibroblasts changes markedly as the healing period from burn wounds progresses, through development of the hypertrophic scar, to resolution of the scar by a self-limiting process of maturation or therapeutic resolution. In addition, hypertrophic scars contain an increased cell proliferation largely made up of fibroblasts. This tremendous population of fibroblasts seems congruous with the abundance of collagen and ground substance. The fine structure of these cells should reflect some aspects of the metabolic activity necessary for production of the scar, and might presage the stage of maturation.A comparison of the fine structure of the fibroblasts from normal skin, different scar types, and granulation tissue has been made by transmission (TEM) and scanning electron microscopy (SEM).


Author(s):  
Venita F. Allison

In 1930, Moore, Hughes and Gallager reported that after castration seminal vesicle epithelial cell atrophy occurred and that cell regeneration could be achieved with daily injections of testis extract. Electron microscopic studies have confirmed those observations and have shown that testosterone injections restore the epithelium of the seminal vesicle in adult castrated male rats. Studies concerned with the metabolism of androgens point out that dihydrotestosterone stimulates cell proliferation and that other metabolites of testosterone probably influence secretory function in certain target cells.Although the influence of androgens on adult seminal vesicle epithelial cytology is well documented, little is known of the effect of androgen depletion and replacement on those cells in aging animals. The present study is concerned with the effect of castration and testosterone injection on the epithelium of the seminal vesicle of aging rats.


Author(s):  
S.S. Poolsawat ◽  
C.A. Huerta ◽  
S.TY. Lae ◽  
G.A. Miranda

Introduction. Experimental induction of altered histology by chemical toxins is of particular importance if its outcome resembles histopathological phenomena. Hepatotoxic drugs and chemicals are agents that can be converted by the liver into various metabolites which consequently evoke toxic responses. Very often, these drugs are intentionally administered to resolve an illness unrelated to liver function. Because of hepatic detoxification, the resulting metabolites are suggested to be integrated into the macromolecular processes of liver function and cause an array of cellular and tissue alterations, such as increased cytoplasmic lysis, centrilobular and localized necroses, chronic inflammation and “foam cell” proliferation of the hepatic sinusoids (1-4).Most experimentally drug-induced toxicity studies have concentrated primarily on the hepatic response, frequently overlooking other physiological phenomena which are directly related to liver function. Categorically, many studies have been short-term effect investigations which seldom have followed up the complications to other tissues and organs when the liver has failed to function normally.


2010 ◽  
Vol 34 (8) ◽  
pp. S50-S50
Author(s):  
Jing Li ◽  
Dongxia Hao ◽  
Weiwei Deng ◽  
Na Li ◽  
Shai Guo ◽  
...  

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