Genome-wide screening reveals essential roles for HOX genes and imprinted genes during caudal neurogenesis of human embryonic stem cells.

Mapping the essential pathways for neuronal differentiation can uncover new therapeutics and models for neurodevelopmental disorders. We thus utilized a genome-wide loss-of-function library in haploid human embryonic stem cells, differentiated into caudal neuronal cells. We show that essential genes for caudal neurogenesis are enriched for secreted and membrane proteins and that a large group of neurological conditions, including neurodegenerative disorders, manifest early neuronal phenotypes.

Genome-wide loss-of-function screen using human pluripotent stem cells to study virus-host interactions for SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019, has become a global health concern. Therefore, there is an immense need to understand the network of virus-host interactions by using human disease-relevant cells. We have thus conducted a loss-of-function genome-wide screen using haploid human embryonic stem cells (hESCs) to identify genes involved in SARS-CoV-2 infection.

Genome-wide screening for genes involved in the epigenetic basis of fragile X syndrome.

Fragile X syndrome (FXS), the most prevalent heritable form of intellectual disability, is caused by the transcriptional silencing of the FMR1 gene. The epigenetic factors responsible for FMR1 inactivation are largely unknown. Here, we initially demonstrated the feasibility of FMR1 reactivation by targeting a single epigenetic factor, DNMT1.

Genome-wide analysis of haploinsufficiency in human embryonic stem cells.

Haploinsufficiency describes a phenomenon where one functioning allele is insufficient for a normal phenotype, underlying several human diseases. The effect of haploinsufficiency on human embryonic stem cells (hESC) has not been thoroughly studied. To establish a genome-wide loss-of-function screening for heterozygous mutations, we fuse normal haploid hESCs with a library of mutant haploid hESCs.

Identifying regulators of parental imprinting by CRISPR/Cas9 screening in haploid human embryonic stem cells.

In mammals, imprinted genes are regulated by differentially methylated regions (DMRs) that are inherited from germ cells, leading to monoallelic expression in accordance with parent-of-origin. Yet, it is largely unknown how imprinted DMRs are maintained in human embryos despite global DNA demethylation following fertilization. Here, we explored the mechanisms involved in imprinting regulation by employing human parthenogenetic embryonic stem cells (hpESCs), which lack paternal alleles.

Cardiac structure and function in response to a multi-stage marathon over 4486 km.

Aims: To investigate whether participation in the Trans Europe Foot Race 2009 (TEFR), an ultramarathon race held over 64 consecutive days and 4486 km, led to changes in cardiac structure and function.

Methods: Cardiac magnetic resonance imaging was performed in 20 of 67 participating runners (two women; mean ± SD age 47.8 ± 10.

Mapping Gene Circuits Essential for Germ Layer Differentiation via Loss-of-Function Screens in Haploid Human Embryonic Stem Cells.

Pluripotent stem cells can differentiate into all embryonic germ layers, yet the genes essential for these cell fate transitions in human remain elusive. Here, we mapped the essential genes for the differentiation of human pluripotent stem cells (hPSCs) into the three germ layers by using a genome-wide loss-of-function library established in haploid hPSCs. Strikingly, we observed a high fraction of essential genes associated with plasma membrane, highlighting signaling pathways needed for each lineage differentiation.

The essentiality landscape of cell cycle related genes in human pluripotent and cancer cells.

Background: Cell cycle regulation is a complex system consisting of growth-promoting and growth-restricting mechanisms, whose coordinated activity is vital for proper division and propagation. Alterations in this regulation may lead to uncontrolled proliferation and genomic instability, triggering carcinogenesis. Here, we conducted a comprehensive bioinformatic analysis of cell cycle-related genes using data from CRISPR/Cas9 loss-of-function screens performed in four cancer cell lines and in human embryonic stem cells (hESCs).

Defining Human Pluripotency.

Human pluripotent stem cells harbor the capacity to differentiate into cells from the three embryonic germ layers, and this ability grants them a central role in modeling human disorders and in the field of regenerative medicine. Here, we review pluripotency in human cells with respect to four different aspects: (1) embryonic development, (2) transcriptomes of pluripotent cell stages, (3) genes and pathways that reprogram somatic cells into pluripotent stem cells, and finally (4) the recent identification of the human pluripotent stem cell essentialome. These four aspects of pluripotency collectively culminate in a broader understanding of what makes a cell pluripotent.

Defining essential genes for human pluripotent stem cells by CRISPR-Cas9 screening in haploid cells.

The maintenance of pluripotency requires coordinated expression of a set of essential genes. Using our recently established haploid human pluripotent stem cells (hPSCs), we generated a genome-wide loss-of-function library targeting 18,166 protein-coding genes to define the essential genes in hPSCs. With this we could allude to an intrinsic bias of essentiality across cellular compartments, uncover two opposing roles for tumour suppressor genes and link autosomal-recessive disorders with growth-retardation phenotypes to early embryogenesis.

Haploid Human Embryonic Stem Cells: Half the Genome, Double the Value.

Recent advances in the generation of haploid embryonic stem cells (ESCs), capable of self-renewal and differentiation, have laid the groundwork for numerous biomedical applications in developmental biology and reproductive medicine. When combined with the power of genetic screening, haploid human ESCs could advance cancer research, regenerative medicine, and disease modeling.

MuSK is a BMP co-receptor that shapes BMP responses and calcium signaling in muscle cells.

Bone morphogenetic proteins (BMPs) function in most tissues but have cell type-specific effects. Given the relatively small number of BMP receptors, this exquisite signaling specificity requires additional molecules to regulate this pathway's output. The receptor tyrosine kinase MuSK (muscle-specific kinase) is critical for neuromuscular junction formation and maintenance.

Ectopic expression of Msx2 in mammalian myotubes recapitulates aspects of amphibian muscle dedifferentiation.

In contrast to urodele amphibians and teleost fish, mammals lack the regenerative responses to replace large body parts. Amphibian and fish regeneration uses dedifferentiation, i.e.

Biglycan recruits utrophin to the sarcolemma and counters dystrophic pathology in mdx mice.

Duchenne muscular dystrophy (DMD) is caused by mutations in dystrophin and the subsequent disruption of the dystrophin-associated protein complex (DAPC). Utrophin is a dystrophin homolog expressed at high levels in developing muscle that is an attractive target for DMD therapy. Here we show that the extracellular matrix protein biglycan regulates utrophin expression in immature muscle and that recombinant human biglycan (rhBGN) increases utrophin expression in cultured myotubes.

Cooperative effects of cofilin (ADF) on actin structure suggest allosteric mechanism of cofilin function.

Using site-specific fluorescence probes and cross-linking we demonstrated that cofilin (ADF), a key regulator of actin cellular dynamics, weakens longitudinal contacts in F-actin in a cooperative manner. Differential scanning calorimetry detected a dual nature of cofilin effects on F-actin conformation. At sub-stoichiometric cofilin to actin ratios, cofilin stabilized sterically and non-cooperatively protomers at the points of attachment, and destabilized allosterically and cooperatively protomers in the cofilin-free parts of F-actin.