Breast Carcinoma-amplified Sequence 2 Regulates Adult Neurogenesis via β-catenin

Mapping Intimacies ◽

10.21203/rs.3.rs-934206/v1 ◽

2021 ◽

Author(s):

Show-Li Chen

Keyword(s):

Gene Therapy ◽

Cell Proliferation ◽

Stem Cell ◽

Breast Carcinoma ◽

Adult Neurogenesis ◽

Conditional Knockout ◽

Wild Type ◽

Stem Cell Proliferation ◽

Intracranial Injection ◽

Immature Neurons

Abstract Background Breast carcinoma-amplified sequence 2 (BCAS2) regulates β-catenin gene splicing. The conditional knockout of BCAS2 expression in the forebrain (BCAS2 cKO) of mice confers impaired learning and memory along with decreased β-catenin expression. Because β-catenin reportedly regulates adult neurogenesis, we wondered whether BCAS2 could regulate adult neurogenesis via β-catenin. Methods BCAS2 regulating neurogenesis was investigated by characterizing BCAS2 cKO mice. Also, lentivirus-shBCAS2 was intracranially injected into the hippocampus of wild-type mice to knock down BCAS2 expression. We evaluated the rescue effects of BCAS2 cKO by intracranial injection of adeno-associated virus encoding BCAS2 (AAV-DJ8-BCAS2) and AAV-β-catenin gene therapy. Results To show that BCAS2-regulating adult neurogenesis via β-catenin, first, BCAS2 cKO mice showed low SRY-box 2–positive (Sox2+) neural stem cell proliferation and doublecortin-positive (DCX+) immature neurons. Second, stereotaxic intracranial injection of lentivirus-shBCAS2 knocked down BCAS2 in the hippocampus of wild-type mice, and we confirmed the BCAS2 regulation of adult neurogenesis via β-catenin. Third, AAV-DJ8-BCAS2 gene therapy in BCAS2 cKO mice reversed the low proliferation of Sox2+ neural stem cells and the decreased number of DCX+ immature neurons with increased β-catenin expression. Moreover, AAV-β-catenin gene therapy restored neuron stem cell proliferation and immature neuron differentiation, which further supports BCAS2 regulating adult neurogenesis via β-catenin. In addition, cells targeted by AAV-DJ8 injection into the hippocampus included Sox2 and DCX immature neurons, interneurons, and astrocytes. BCAS2 may regulate adult neurogenesis by targeting Sox2+ and DCX+ immature neurons for autocrine effects and interneurons or astrocytes for paracrine effects. Conclusions BCAS2 can regulate adult neurogenesis in mice via β-catenin.

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Excessive Hematopoietic Stem Cell Proliferation Leads to Chromosomal Instability

Blood ◽

10.1182/blood.v112.11.4772.4772 ◽

2008 ◽

Vol 112 (11) ◽

pp. 4772-4772

Author(s):

Liliana Souza ◽

Natalyn Hawk ◽

Sweta Sengupta ◽

Carlos Cabrera ◽

Morgan L. McLemore

Keyword(s):

Cell Cycle ◽

Stem Cells ◽

Cell Proliferation ◽

Stem Cell ◽

Chromosomal Instability ◽

Wild Type ◽

Dna Breaks ◽

Hematopoietic Stem ◽

Stem Cell Proliferation ◽

Double Stranded Dna

Abstract Truncation mutations in the granulocyte colony stimulating factor receptor (G-CSFR), common in severe congenital neutropenia (SCN), lead to excessive stem cell proliferation in response to G-CSF. These G-CSFR mutants are (at least indirectly) implicated in the progression of these patients to acute leukemia. Since SCN patients require continuous G-CSF treatment throughout their lifespan, we hypothesize that excessive stem cell proliferation can lead to DNA damage. Stem cells are relatively quiescent and rarely enter the cell cycle under normal conditions. During the cell cycle cells generate approximately 5000 single strand DNA lesions per nucleus (Vilenchik and Knudson, 2003). Approximately 1% of these lesions are ultimately converted to double strand DNA breaks (DSBs). Hematopoietic stem cells are found within the Sca+ ckit+ Lin- (KLS) population. Wild type and mice bearing a mutant G-CSFR similar to that found in patients with SCN were treated with G-CSF. After 21 days of treatment with G-CSF (10 ug/kg/day), the KLS population in the bone marrow increased four-fold in wild type mice and eight-fold in mutant mice. We isolated Lin-Sca+ bone marrow cells from these G-CSF treated mice and evaluated for the presence of double stranded DNA breaks by staining with anti-phospho-H2AX by immunofluorescence. H2AX is a histone whose phosphorylated form localizes to the site of double stranded DNA breaks. The results showed that there is an 8-fold increase in the DSB in wild type Lin-Sca+ and 10-fold in mutant Lin-Sca+ when compared to cells from untreated mice. This data suggests that excessive proliferation can contribute to an increase in DSBs in hematopoietic stem cells. Investigation of potential mechanisms contributing to DSB formation are ongoing. Understanding the causes and trends of chromosomal instability would improve our understanding of leukemogenesis and potentially reveal novel treatment strategies.

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The C-terminal Pentapeptide of Nanog Tryptophan Repeat Domain Interacts with Nac1 and Regulates Stem Cell Proliferation but Not Pluripotency

Journal of Biological Chemistry ◽

10.1074/jbc.m109.005041 ◽

2009 ◽

Vol 284 (24) ◽

pp. 16071-16081 ◽

Cited By ~ 19

Author(s):

Tianhua Ma ◽

Zhe Wang ◽

Yunqian Guo ◽

Duanqing Pei

Keyword(s):

Cell Cycle ◽

Cell Proliferation ◽

Stem Cell ◽

Es Cells ◽

Embryonic Stem ◽

Akt Pathway ◽

Wild Type ◽

Phosphatidylinositol 3 Kinase ◽

Stem Cell Proliferation ◽

Phosphatidylinositol 3

Overexpression of Nanog in mouse embryonic stem (ES) cells has been shown to abrogate the requirement of leukemia inhibitory factor for self-renewal in culture. Little is known about the molecular mechanism of Nanog function. Here we describe the role of the tryptophan repeat (WR) domain, one of the two transactivators at its C terminus, in regulating stem cell proliferation as well as pluripotency. We first created a supertransactivator, W2W3×10, by duplicating repeats W2W3 10 times and discovered that it can functionally substitute for wild type WR at sustaining pluripotency, albeit with a significantly slower cell cycle, phenocopying Nanog(9W) with the C-terminal pentapeptide (WNAAP) of WR deleted. ES cells carrying both W2W3×10 and Nanog(9W) have a longer G1 phase, a shorter S phase in cell cycle distribution and progression analysis, and a lower level of pAkt(Ser473) compared with wild type Nanog, suggesting that both mutants impact the cell cycle machinery via the phosphatidylinositol 3-kinase/Akt pathway. Both mutants remain competent in dimerizing with Nanog but cannot form a complex with Nac1 efficiently, suggesting that WNAAP may be involved in Nac1 binding. By tagging Gal4DBD with WNAAP, we demonstrated that this pentapeptide is sufficient to confer Nac1 binding. Furthermore, we can rescue W2W3×10 by placing WNAAP at the corresponding locations. Finally, we found that Nanog and Nac1 synergistically up-regulate ERas expression and promote the proliferation of ES cells. These results suggest that Nanog interacts with Nac1 through WNAAP to regulate the cell cycle of ES cells via the ERas/phosphatidylinositol 3-kinase/Akt pathway, but not pluripotency, thus decoupling cell cycle control from pluripotency.

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