The Photocleavable Protein PhoCl-Based Dynamic Hydrogels.

Dynamic protein hydrogels have attracted increasing attention owing to their tunable physiochemical and mechanical properties, customized functionality, and biocompatibility. Among the different types of dynamic hydrogels, photoresponsive hydrogels are of particular interest. Here, we report the engineering of a photoresponsive protein hydrogel by using the photocleavable protein PhoCl.

Retinal Development and Pathophysiology in Kcnj13 Knockout Mice.

We constructed and characterized knockout and conditional knockout mice for KCNJ13, encoding the inwardly rectifying K channel of the Kir superfamily Kir7.1, mutations in which cause both Snowflake Vitreoretinal Degeneration (SVD) and Retinitis pigmentosa (RP) to further elucidate the pathology of this disease and to develop a potential model system for gene therapy trials. A Kcnj13 knockout mouse line was constructed by inserting a gene trap cassette expressing beta-galactosidase flanked by FRT sites in intron 1 with LoxP sites flanking exon two and converted to a conditional knockout by FLP recombination followed by crossing with C57BL/6J mice having Cre driven by the VMD2 promoter.

Restoration of RPGR expression in vivo using CRISPR/Cas9 gene editing.

Mutations in the gene for Retinitis Pigmentosa GTPase Regulator (RPGR) cause the X-linked form of inherited retinal degeneration, and the majority are frameshift mutations in a highly repetitive, purine-rich region of RPGR known as the OFR15 exon. Truncation of the reading frame in this terminal exon ablates the functionally important C-terminal domain. We hypothesized that targeted excision in ORF15 by CRISPR/Cas9 and the ensuing repair by non-homologous end joining could restore RPGR reading frame in a portion of mutant photoreceptors thereby correcting gene function in vivo.

Targeted deletion of an NRL- and CRX-regulated alternative promoter specifically silences FERM and PDZ domain containing 1 (Frmpd1) in rod photoreceptors.

Regulation of cell type-specific gene expression is critical for generating neuronal diversity. Transcriptome analyses have unraveled extensive heterogeneity of transcribed sequences in retinal photoreceptors because of alternate splicing and/or promoter usage. Here we show that Frmpd1 (FERM and PDZ domain containing 1) is transcribed from an alternative promoter specifically in the retina.

Creating Knockin Alleles in Mouse Embryonic Stem Cells by CRISPR/Cas9-Mediated Homologous Recombination Without Drug Selection.

The rapidly evolving CRISPR/Cas9-mediated genome editing provides the convenience of genome manipulation directly in mouse zygotes for a number of genomic manipulations; but knockins of large insertions prove to be relatively inefficient at least with double-strand DNA as targeting constructs. Here, we describe an alternative approach to the direct genome editing in mouse zygotes by generating knockin alleles in mouse embryonic stem cells first with CRIPSR-mediated homologous recombination. Our results show this approach is efficient and requires no drug selection in mouse embryonic stem cells as in classic gene targeting.

Maturation arrest in early postnatal sensory receptors by deletion of the miR-183/96/182 cluster in mouse.

The polycistronic miR-183/96/182 cluster is preferentially and abundantly expressed in terminally differentiating sensory epithelia. To clarify its roles in the terminal differentiation of sensory receptors in vivo, we deleted the entire gene cluster in mouse germline through homologous recombination. The miR-183/96/182 null mice display impairment of the visual, auditory, vestibular, and olfactory systems, attributable to profound defects in sensory receptor terminal differentiation.

Prickle1 is expressed in distinct cell populations of the central nervous system and contributes to neuronal morphogenesis.

Development of axons and dendrites constitutes a critical event in neuronal maturation and seems to require signaling through the planar cell polarity (PCP) pathway. Mutations in components of the PCP pathway lead to a spectrum of neurological phenotypes and disorders. For example, a missense mutation in Prickle 1 (Pk1) is associated with progressive myoclonus epilepsy (PME) in humans, and its reduced gene dosage increases sensitivity to induced seizure in mice.

From tissue phenotype to proteotype: sensitive protein identification in microdissected tumor tissue.

Correlation of disease phenotype with protein profile (proteotype) is a significant challenge for biomedical research. The main obstacles have been the need to insure sufficient quantities of pure protein sample, the reproducibility of protein display, and rapid and accurate protein identification. We present a modified approach that combines enhanced detection sensitivity with tissue microdissection from frozen primary renal cancer tissues of different histological subtypes, followed by 2D gel analysis and protein identification with MALDI mass spectrometry.

Protein patterns and proteins that identify subtypes of glioblastoma multiforme.

Glioblastoma multiforme (GBM) has been subdivided into two types based on clinical and genetic findings: primary tumors, which arise de novo, and secondary tumors, which progress from lower grade gliomas to GBMs. To analyse this dichotomy at the protein level, we employed selective tissue microdissection to obtain pure populations of tumor cells, which we studied using two-dimensional protein gel electrophoresis (2-DGE) and protein sequencing of select target proteins. Protein patterns were analysed in a blinded manner from the clinical and genetic data.

Multilineage potential of homozygous stem cells derived from metaphase II oocytes.

Human stem cells derived from human fertilized oocytes, fetal primordial germ cells, umbilical cord blood, and adult tissues provide potential cell-based therapies for repair of degenerating or damaged tissues. However, the diversity of major histocompatibility complex (MHC) antigens in the general population and the resultant risk of immune-mediated rejection complicates the allogenic use of established stem cells. We assessed an alternative approach, employing chemical activation of nonfertilized metaphase II oocytes for producing stem cells homozygous for MHC.