p53 inhibits CRISPR-Cas9 engineering in human pluripotent stem cells.

CRISPR/Cas9 has revolutionized our ability to engineer genomes and conduct genome-wide screens in human cells. Whereas some cell types are amenable to genome engineering, genomes of human pluripotent stem cells (hPSCs) have been difficult to engineer, with reduced efficiencies relative to tumour cell lines or mouse embryonic stem cells. Here, using hPSC lines with stable integration of Cas9 or transient delivery of Cas9-ribonucleoproteins (RNPs), we achieved an average insertion or deletion (indel) efficiency greater than 80%.

A high-throughput screen for Wnt/β-catenin signaling pathway modulators in human iPSC-derived neural progenitors.

Wnt/β-catenin signaling has emerged as a central player in pathways implicated in the pathophysiology and treatment of neuropsychiatric disorders. To identify potential novel therapeutics for these disorders, high-throughput screening (HTS) assays reporting on Wnt/β-catenin signaling in disease-relevant contexts are needed. The use of human patient-derived induced pluripotent stem cell (iPSC) models provides ideal disease-relevant context if these stem cell cultures can be adapted for HTS-compatible formats.

Epigenetic characterization of the FMR1 gene and aberrant neurodevelopment in human induced pluripotent stem cell models of fragile X syndrome.

Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability. In addition to cognitive deficits, FXS patients exhibit hyperactivity, attention deficits, social difficulties, anxiety, and other autistic-like behaviors. FXS is caused by an expanded CGG trinucleotide repeat in the 5' untranslated region of the Fragile X Mental Retardation (FMR1) gene leading to epigenetic silencing and loss of expression of the Fragile X Mental Retardation protein (FMRP).

Sexual differentiation of identified motor terminals in Drosophila larvae.

In Drosophila, we have found that some of the motor terminals in wandering third-instar larvae are sexually differentiated. In three out of the four body-wall muscle fibers that we examined, we found female terminals that produced a larger synaptic response than their male counterparts. The single motor terminal that innervates muscle fiber 5 produces an EPSP that is 69% larger in females than in males.

Mechanisms of postinhibitory rebound and its modulation by serotonin in excitatory swim motor neurons of the medicinal leech.

Postinhibitory rebound (PIR) is defined as membrane depolarization occurring at the offset of a hyperpolarizing stimulus and is one of several intrinsic properties that may promote rhythmic electrical activity. PIR can be produced by several mechanisms including hyperpolarization-activated cation current (I(h)) or de-inactivation of depolarization-activated inward currents. Excitatory swim motor neurons in the leech exhibit PIR in response to injected current pulses or inhibitory synaptic input.