Dataset Information

Survivin safeguards chromosome numbers and protects from aneuploidy independently from p53.

ABSTRACT:

Background

Survivin, a member of the inhibitor of apoptosis (IAP) gene family, has a dual role in mitosis and in apoptosis. It is abundantly expressed in every human tumor, compared with normal tissues. During mitosis Survivin assembles with the chromosomal passenger complex and regulates chromosomal segregation. Here, we aim to explore whether interference with the mitotic function of Survivin is linked to p53-mediated G1 cell cycle arrest and affects chromosomal stability.

Methods

In this study, we used HCT116, SBC-2, and U87-MG and generated corresponding isogenic p53-deficient cells. Retroviral vectors were used to stably knockdown Survivin. The resulting phenotype, in particular the mechanisms of cell cycle arrest and of initiation of aneuploidy, were investigated by Western Blot analysis, confocal laser scan microscopy, proliferation assays, spectral karyotyping and RNAi.

Results

In all cell lines Survivin-RNAi did not induce instant apoptosis but caused polyplodization irrespective of p53 status. Strikingly, polyploidization after knockdown of Survivin resulted in merotelic kinetochore spindle assemblies, γH2AX-foci, and DNA damage response (DDR), which was accompanied by a transient p53-mediated G1-arrest. That p53 wild type cells specifically arrest due to DNA damage was shown by simultaneous inhibition of ATM and DNA-PK, which abolished induction of p21waf/cip. Cytogenetic analysis revealed chromosomal aberrations indicative for DNA double strand break repair by the mechanism of non-homologous end joining (NHEJ), only in Survivin-depleted cells.

Conclusion

Our findings suggest that Survivin plays an essential role in proper amphitelic kinetochore-spindle assembly and that constraining Survivin's mitotic function results in polyploidy and aneuploidy which cannot be controlled by p53. Therefore, Survivin critically safeguards chromosomal stability independently from p53.

SUBMITTER: Wiedemuth R

PROVIDER: S-EPMC4041913 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:The detrimental role of hepatic lipotoxicity has been well-implicated in the pathogenesis of NAFLD. Previously, we reported that inhibiting autophagy aggravated saturated fatty acid (SFA)-induced hepatotoxicity. Insulin, a physiological inhibitor of autophagy, is commonly increased within NAFLD mainly caused by insulin resistance. We therefore hypothesized that insulin augments the sensitivity of hepatocyte to SFA-induced lipotoxicity. The present study was conducted via employing human and mouse hepatocytes, which were exposed to SFAs, insulin, or their combination. Unexpectedly, our results indicated that insulin protected hepatocytes against SFA-induced lipotoxicity, based on the LDH, MTT, and nuclear morphological measurements, and the detection from cleaved-Parp-1 and -caspase-3 expressions. We subsequently clarified that insulin led to a rapid and short-period inhibition of autophagy, which was gradually recovered after 1 h incubation in hepatocytes, and such extent of inhibition was insufficient to aggravate SFA-induced lipotoxicity. The mechanistic study revealed that insulin-induced alleviation of ER stress contributed to its hepatoprotective role. Pre-treating hepatocytes with insulin significantly stimulated phosphorylated-Akt and reversed SFA-induced up-regulation of p53. Chemical inhibition of p53 by pifithrin-? robustly prevented palmitate-induced cell death. The PI3K/Akt pathway blockade by its special antagonist abolished the protective role of insulin against SFA-induced lipotoxicity and p53 up-regulation. Furthermore, we observed that insulin promoted intracellular TG deposits in hepatocytes in the present of palmitate. However, blocking TG accumulation via genetically silencing DGAT-2 did not prevent insulin-protected lipotoxicity. Our study demonstrated that insulin strongly protected against SFA-induced lipotoxicity in hepatocytes mechanistically through alleviating ER stress via a PI3K/Akt/p53 involved pathway but independently from autophagy.

Project description:Esophageal cancer is one of the most common cancers where TP53 is mutated frequently. Esophageal squamous cell carcinoma (ESCC) is the major subtype of esophageal cancer, and is one of the most lethal cancers worldwide. ESCC evolves often to lung metastasis, which is associated with a dismal prognosis. P53R175H (homologous to Trp53R172H in mice) is a common hot spot mutation. How metastasis is regulated by p53R175H in ESCC, or cancers in general, remains to be elucidated. To investigate p53R175H mediated molecular mechanisms, we utilized germline Trp53R172H/- mice, and generated esophageal specific Trp53-/- mice and Trp53+/+ mice treated with the 4-NQO esophageal-specific carcinogen (a common exposure in humans) to model ESCC. In the primary Trp53R172H/- tumor cell lines established from these mouse models, we depleted Trp53R172H (shTrp53) and observed a marked reduction in cell invasion in vitro and lung metastasis burden in a tail-vein injection model in comparing isogenic cells (shCtrl). Furthermore, to understand the molecular basis for mutant p53 driven lung metastasis, we performed bulk RNA-seq to compare gene expression profiles of metastatic and primary shCtrl and shTrp53 cells. We performed Gene Set Enrichment Analysis (GSEA) and identified the YAP-BIRC5 axis as a potential mediator of Trp53R172H mediated metastasis. As a target gene of YAP, BIRC5 encodes an anti-apoptotic protein, namely survivin. We demonstrate that survivin expression increases in the presence of Trp53R172H but not wild-type Trp53. Furthermore, depletion of survivin decreases Trp53R172H driven lung metastasis. Mechanistically, Trp53R172H but not wild-type Trp53, binds with YAP in ESCC cells, suggesting their cooperation to induce survivin expression. Furthermore, survivin high expression level is associated with increased metastasis in several GI cancer, suggesting that survivin may be a key regulator to metastasis. Taken together, this study unravels new insights into how mutant p53 mediates metastasis.

Project description:BackgroundSex chromosome aneuploidies (SCAs) are a collectively common family of genetic disorders that increase the risk for neuropsychiatric and cognitive impairment. Beyond being important medical disorders in their own right, SCAs also offer a unique naturally occurring model for studying X- and Y-chromosome influences on the human brain. However, it remains unclear if (i) different SCAs are associated with different profiles of psychopathology and (ii) the notable interindividual variation in psychopathology is related to co-occurring variation in cognitive ability.MethodsWe examined scores for 11 dimensions of psychopathology [Child/Adult Behavior Checklist (CBCL)] and general cognitive ability [full-scale IQ (FSIQ) from Wechsler tests] in 110 youth with varying SCAs (XXY = 41, XYY = 22, XXX = 27, XXYY = 20) and 131 typically developing controls (XX = 59, XY = 72).ResultsAll SCAs were associated with elevated CBCL scores across several dimensions of psychopathology (two-sample t tests comparing the euploidic and aneuploidic groups [all |T| > 9, and p < 0.001]). Social and attentional functioning were particularly sensitive to the carriage of a supernumerary Y-chromosome. In particular, the XYY group evidenced significantly more social problems than both extra-X groups (Cohen's d effect size > 0.5, Bonferroni corrected p < .05). There was marked variability in CBCL scores within each SCA group, which generally correlated negatively with IQ, but most strongly so for social and attentional difficulties (standardized β, - 0.3). These correlations showed subtle differences as a function of the SCA group and CBCL scale.ConclusionsThere is domain-specific variation in psychopathology across SCA groups and domain-specific correlation between psychopathology and IQ within SCAs. These findings (i) help to tailor clinical assessment of this common and impactful family of genetic disorders and (ii) suggest that dosage abnormalities of X- and Y-linked genes impart somewhat distinct profiles of neuropsychiatric risk.