Data from Haploinsufficiency of an RB–E2F1–Condensin II Complex Leads to Aberrant Replication and Aneuploidy
Courtney H. CoschiCharles A. IshakDavid A. GalloAren E. MarshallSrikanth TalluriJianxin WangMatthew J. CecchiniAlison L. MartensVanessa PercyIan WelchPaul C. BoutrosGrant W. BrownFrederick A. Dick
0
Citation
0
Reference
10
Related Paper
Abstract:
<div>Abstract<p>Genome instability is a characteristic of malignant cells; however, evidence for its contribution to tumorigenesis has been enigmatic. In this study, we demonstrate that the retinoblastoma protein, E2F1, and Condensin II localize to discrete genomic locations including major satellite repeats at pericentromeres. In the absence of this complex, aberrant replication ensues followed by defective chromosome segregation in mitosis. Surprisingly, loss of even one copy of the retinoblastoma gene reduced recruitment of Condensin II to pericentromeres and caused this phenotype. Using cancer genome data and gene-targeted mice, we demonstrate that mutation of one copy of <i>RB1</i> is associated with chromosome copy-number variation in cancer. Our study connects DNA replication and chromosome structure defects with aneuploidy through a dosage-sensitive complex at pericentromeric repeats.</p><p><b>Significance:</b> Genome instability is inherent to most cancers and is the basis for selective killing of cancer cells by genotoxic therapeutics. In this report, we demonstrate that instability can be caused by loss of a single allele of the retinoblastoma gene that prevents proper replication and condensation of pericentromeric chromosomal regions, leading to elevated levels of aneuploidy in cancer. <i>Cancer Discov; 4(7); 840–53. ©2014 AACR</i>.</p><p>See related commentary by Hinds, p. 764</p><p>This article is highlighted in the In This Issue feature, p. 745</p></div>Keywords:
Haploinsufficiency
Replication
Condensin
A wide range of human diseases result from haploinsufficiency, where the function of one of the two gene copies is lost. Here, we targeted the remaining functional copy of a haploinsufficient gene using CRISPR-mediated activation (CRISPRa) in Sim1 and Mc4r heterozygous mouse models to rescue their obesity phenotype. Transgenic-based CRISPRa targeting of the Sim1 promoter or its distant hypothalamic enhancer up-regulated its expression from the endogenous functional allele in a tissue-specific manner, rescuing the obesity phenotype in Sim1 heterozygous mice. To evaluate the therapeutic potential of CRISPRa, we injected CRISPRa-recombinant adeno-associated virus into the hypothalamus, which led to reversal of the obesity phenotype in Sim1 and Mc4r haploinsufficient mice. Our results suggest that endogenous gene up-regulation could be a potential strategy to treat altered gene dosage diseases.
Haploinsufficiency
Cite
Citations (271)
Abstract Inhibitory interneurons are essential for proper brain development and function. Dysfunction of interneurons is implicated in several neurodevelopmental disorders, including autism spectrum disorder (ASD) and intellectual disability (ID). We have previously shown that Arid1b haploinsufficiency interferes with interneuron development and leads to social, cognitive, and emotional impairments consistent with ASD and ID. It is unclear, however, whether interneurons play a major role for the behavioral deficits in Arid1b haploinsufficiency. Furthermore, it is critical to determine which interneuron subtypes contribute to distinct behavioral phenotypes. In the present study, we generated Arid1b haploinsufficient mice in which a copy of the Arid1b gene is deleted in either parvalbumin (PV) or somatostatin (SST) interneurons, and examined their ASD- and ID-like behaviors. We found that Arid1b haploinsufficiency in PV or SST interneurons resulted in distinct features that do not overlap with one another. Arid1b haploinsufficiency in PV neurons contributed to social and emotional impairments, while the gene deletion in the SST population caused stereotypies as well as learning and memory dysfunction. These findings demonstrate a critical role of interneurons in Arid1b haploinsufficient pathology and suggest that PV and SST interneurons may have distinct roles in modulating neurological phenotypes in Arid1b haploinsufficiency-induced ASD and ID.
Haploinsufficiency
Interneuron
Cite
Citations (32)
Two cases of newborns with deletion 13q syndrome were identified and studied using electron microscopy and histologic, immunohistochemical, and special stained sections. We reviewed the published literature on genes that are haploinsufficient in the deletion 13q syndrome. The complexity of the deletion 13q syndrome phenotype is due at least in part to the haploinsufficiency of dosage-sensitive genes. Future studies need to be performed to identify their precise role in the cellular function and the development of the deletion 13q syndrome phenotype.
Haploinsufficiency
Loss function
Cite
Citations (8)
Haploinsufficiency, a dominant phenotype caused by a heterozygous loss-of-function mutation, has been rarely observed. However, high-dimensional single-cell phenotyping of yeast morphological characteristics revealed haploinsufficiency phenotypes for more than half of 1,112 essential genes under optimal growth conditions. Additionally, 40% of the essential genes with no obvious phenotype under optimal growth conditions displayed haploinsufficiency under severe growth conditions. Haploinsufficiency was detected more frequently in essential genes than in nonessential genes. Similar haploinsufficiency phenotypes were observed mostly in mutants with heterozygous deletion of functionally related genes, suggesting that haploinsufficiency phenotypes were caused by functional defects of the genes. A global view of the gene network was presented based on the similarities of the haploinsufficiency phenotypes. Our dataset contains rich information regarding essential gene functions, providing evidence that single-cell phenotyping is a powerful approach, even in the heterozygous condition, for analyzing complex biological systems.
Haploinsufficiency
Gene regulatory network
Cite
Citations (47)
Haploinsufficiency is defined as a dominant phenotype in diploid organisms that are heterozygous for a loss-of-function allele. Despite its relevance to human disease, neither the extent of haploinsufficiency nor its precise molecular mechanisms are well understood. We used the complete set of Saccharomyces cerevisiae heterozygous deletion strains to survey the genome for haploinsufficiency via fitness profiling in rich (YPD) and minimal media to identify all genes that confer a haploinsufficient growth defect. This assay revealed that approximately 3% of all approximately 5900 genes tested are haploinsufficient for growth in YPD. This class of genes is functionally enriched for metabolic processes carried out by molecular complexes such as the ribosome. Much of the haploinsufficiency in YPD is alleviated by slowing the growth rate of each strain in minimal media, suggesting that certain gene products are rate limiting for growth only in YPD. Overall, our results suggest that the primary mechanism of haploinsufficiency in yeast is due to insufficient protein production. We discuss the relevance of our findings in yeast to human haploinsufficiency disorders.
Haploinsufficiency
Cite
Citations (540)
Haploinsufficiency
Nonsense mutation
Nonsense
Nonsense-Mediated Decay
Cite
Citations (4)
Haploinsufficiency
Loss function
Cite
Citations (1)
Haploinsufficiency of the methyl-CpG-binding domain protein 5 ( MBD5 ) gene causes a neurodevelopmental disorder that includes intellectual disability, developmental delay, speech impairment, seizures, sleep disturbances, and behavioral difficulties. Microdeletion of 2q23.1 is the most common cause of haploinsufficiency, although MBD5 haploinsufficiency may also cause this genetic disorder. We report a family harboring a heterozygous loss-of-function variant in MBD5 (NM_018328.5:c.728delC; p.Pro243His fs *26), which includes three affected siblings with varying phenotypic features. Both parents were phenotypically normal but deep coverage sequencing of the parents showed germline mosaicism in the mother.
Haploinsufficiency
Neurodevelopmental disorder
Cite
Citations (0)
Haploinsufficiency describes the decrease in organismal fitness observed when a single copy of a gene is deleted in diploids. We investigated the origin of haploinsufficiency by creating a comprehensive dosage sensitivity data set for genes under their native promoters. We demonstrate that the expression of haploinsufficient genes is limited by the toxicity of their overexpression. We further show that the fitness penalty associated with excess gene copy number is not the only determinant of haploinsufficiency. Haploinsufficient genes represent a unique subset of genes sensitive to copy number increases, as they are also limiting for important cellular processes when present in one copy instead of two. The selective pressure to decrease gene expression due to the toxicity of overexpression, combined with the pressure to increase expression due to their fitness-limiting nature, has made haploinsufficient genes extremely sensitive to changes in gene expression. As a consequence, haploinsufficient genes are dosage stabilized, showing much more narrow ranges in cell-to-cell variability of expression compared with other genes in the genome. We propose a dosage-stabilizing hypothesis of haploinsufficiency to explain its persistence over evolutionary time.
Haploinsufficiency
Cite
Citations (77)