A small molecule that induces translational readthrough of CFTR nonsense mutations by eRF1 depletion.

Premature termination codons (PTCs) prevent translation of a full-length protein and trigger nonsense-mediated mRNA decay (NMD). Nonsense suppression (also termed readthrough) therapy restores protein function by selectively suppressing translation termination at PTCs. Poor efficacy of current readthrough agents prompted us to search for better compounds. An NMD-sensitive NanoLuc readthrough reporter was used to screen 771,345 compounds. Among the 180 compounds identified with readthrough activity, SRI-37240 and its more potent derivative SRI-41315, induce a prolonged pause at stop codons and suppress PTCs associated with cystic fibrosis in immortalized and primary human bronchial epithelial cells, restoring CFTR expression and function. SRI-41315 suppresses PTCs by reducing the abundance of the termination factor eRF1. SRI-41315 also potentiates aminoglycoside-mediated readthrough, leading to synergistic increases in CFTR activity. Combining readthrough agents that target distinct components of the translation machinery is a promising treatment strategy for diseases caused by PTCs.

Dynamic intrinsic optical signal monitoring of electrically stimulated inner retinal neural response.

Dynamic monitoring of stimulus-evoked inner neural response is important for functional validation of stimulation protocols of retinal prosthetic devices. In this paper, we demonstrate label-free intrinsic optical signal (IOS) imaging of electrically stimulated inner neural response in freshly isolated mouse retinas. While single-pulse stimulation evoked rapid IOS within 20 ms, pulse-train stimulation indicated that the fast IOS response can follow frequency stimulation up to at least 8 Hz. Fast IOS imaging promises a noninvasive method for high resolution examination of electrically evoked retinal response, without artifact contamination of electrical stimulus.

PRC2 complexes with JARID2, MTF2, and esPRC2p48 in ES cells to modulate ES cell pluripotency and somatic cell reprogramming.

Polycomb repressive complex two (PRC2) has been implicated in embryonic stem (ES) cell pluripotency; however, the mechanistic roles of this complex are unclear. It was assumed that ES cells contain PRC2 with the same subunit composition as that identified in HeLa cells and Drosophila embryos. Here, we report that PRC2 in mouse ES cells contains at least three additional subunits: JARID2, MTF2, and a novel protein denoted esPRC2p48. JARID2, MTF2, and esPRC2p48 are highly expressed in mouse ES cells compared to differentiated cells. Importantly, knockdowns of JARID2, MTF2, or esPRC2p48 alter the level of PRC2-mediated H3K27 methylation and result in the expression of differentiation-associated genes in ES cells. Interestingly, expression of JARID2, MTF2, and esPRC2p48 together, but not individually, enhances Oct4/Sox2/Klf4-mediated reprogramming of mouse embryonic fibroblasts (MEFs) into induced pluripotent stem cells, whereas knockdown or knockout of JARID2, MTF2, or esPRC2p48 significantly inhibits reprogramming. JARID2, MTF2, and esPRC2p48 modulate H3K27 methylation and facilitate repression of lineage-associated gene expression when transduced into MEFs, and synergistically stimulate the histone methyltransferase activity of PRC2 in vitro. Therefore, these studies identify JARID2, MTF2, and esPRC2p48 as important regulatory subunits of PRC2 in ES cells and reveal critical functions of these subunits in modulating PRC2's activity and gene expression both in ES cells and during somatic cell reprogramming.

KLF1 regulates BCL11A expression and gamma- to beta-globin gene switching.

We show that knockdown of KLF1 in human and mouse adult erythroid progenitors markedly reduces BCL11A levels and increases human gamma-globin/beta-globin expression ratios. These results suggest that KLF1 controls globin gene switching by directly activating beta-globin and indirectly repressing gamma-globin gene expression. Controlled knockdown of KLF1 in adult erythroid progenitors may provide a method to activate fetal hemoglobin expression in individuals with beta-thalassemia or sickle cell disease.

Polycistronic lentiviral vector for "hit and run" reprogramming of adult skin fibroblasts to induced pluripotent stem cells.

We report the derivation of induced pluripotent stem (iPS) cells from adult skin fibroblasts using a single, polycistronic lentiviral vector encoding the reprogramming factors Oct4, Sox2, and Klf4. Porcine teschovirus-1 2A sequences that trigger ribosome skipping were inserted between human cDNAs for these factors, and the polycistron was subcloned downstream of the elongation factor 1 alpha promoter in a self-inactivating (SIN) lentiviral vector containing a loxP site in the truncated 3' long terminal repeat (LTR). Adult skin fibroblasts from a humanized mouse model of sickle cell disease were transduced with this single lentiviral vector, and iPS cell colonies were picked within 30 days. These cells expressed endogenous Oct4, Sox2, Nanog, alkaline phosphatase, stage-specific embryonic antigen-1, and other markers of pluripotency. The iPS cells produced teratomas containing tissue derived from all three germ layers after injection into immunocompromised mice and formed high-level chimeras after injection into murine blastocysts. iPS cell lines with as few as three lentiviral insertions were obtained. Expression of Cre recombinase in these iPS cells resulted in deletion of the lentiviral vector, and sequencing of insertion sites demonstrated that remnant 291-bp SIN LTRs containing a single loxP site did not interrupt coding sequences, promoters, or known regulatory elements. These results suggest that a single, polycistronic "hit and run" vector can safely and effectively reprogram adult dermal fibroblasts into iPS cells.

Overexpression of OsCOIN, a putative cold inducible zinc finger protein, increased tolerance to chilling, salt and drought, and enhanced proline level in rice.

Rice (Oryza sativa L.) plant is sensitive to chilling, particularly at early stages of seedling development. Here a novel cold-inducible gene, designated OsCOIN (Oryza sativa cold-inducible), was isolated and characterized. Results showed that OsCOIN protein, a RING finger protein, was localized in both nuclear and cytoplasm membrane. OsCOIN is expressed in all rice organs and strongly induced by low temperature, ABA, salt and drought. Over-expression of OsCOIN in transgenic rice lines significantly enhanced their tolerance to cold, salt and drought, accompanied by an up-regulation of OsP5CS expression and an increase of cellular proline level.