A CRISPR-based assay for the study of eukaryotic DNA repair onboard the International Space Station.

As we explore beyond Earth, astronauts may be at risk for harmful DNA damage caused by ionizing radiation. Double-strand breaks are a type of DNA damage that can be repaired by two major cellular pathways: non-homologous end joining, during which insertions or deletions may be added at the break site, and homologous recombination, in which the DNA sequence often remains unchanged. Previous work suggests that space conditions may impact the choice of DNA repair pathway, potentially compounding the risks of increased radiation exposure during space travel. However, our understanding of this problem has been limited by technical and safety concerns, which have prevented integral study of the DNA repair process in space. The CRISPR/Cas9 gene editing system offers a model for the safe and targeted generation of double-strand breaks in eukaryotes. Here we describe a CRISPR-based assay for DNA break induction and assessment of double-strand break repair pathway choice entirely in space. As necessary steps in this process, we describe the first successful genetic transformation and CRISPR/Cas9 genome editing in space. These milestones represent a significant expansion of the molecular biology toolkit onboard the International Space Station.

Self-organization and progenitor targeting generate stable patterns in planarian regeneration.

During animal regeneration, cells must organize into discrete and functional systems. We show that self-organization, along with patterning cues, govern progenitor behavior in planarian regeneration. Surgical paradigms allowed the manipulation of planarian eye regeneration in predictable locations and numbers, generating alternative stable neuroanatomical states for wild-type animals with multiple functional ectopic eyes. We used animals with multiple ectopic eyes and eye transplantation to demonstrate that broad progenitor specification, combined with self-organization, allows anatomy maintenance during regeneration. We propose a model for regenerative progenitors involving (i) migratory targeting cues, (ii) self-organization into existing or regenerating eyes, and (iii) a broad zone, associated with coarse progenitor specification, in which eyes can be targeted by progenitors. These three properties help explain how tissues can be organized during regeneration.

Knockdown of Pin1 leads to reduced angiogenic potential and tumorigenicity in glioblastoma cells.

Glioblastoma is the most common and most aggressive type of primary brain tumor. Current approaches in the treatment of glioblastoma are not effective enough to increase patient survival or prevent recurrence following surgery. Consequently, the search for potential drug targets is ongoing. Peptidyl-prolyl cis/trans isomerase NIMA-interacting 1 (Pin1), an isomerase that is overexpressed in various tumors, has become an attractive molecule in cancer research. Pin1 has been reported to regulate proteins involved in essential cellular pathways that mediate cell proliferation, cell cycle progression, differentiation and apoptosis, by altering their stability and function. The results of the present study revealed that knockdown of Pin1 in glioblastoma cells using RNA interference or the selective Pin1 inhibitor, juglone, suppressed the tumorigenic features by reducing cell growth, migration and angiogenic potential. Furthermore, knockdown of Pin1 decreased the levels of vascular endothelial growth factor and matrix metallopeptidase 9, and also triggered apoptosis. Due to the fundamental roles of Pin1 in promoting tumorigenesis, Pin1 inhibitory molecules, including juglone, or alternative synthetic derivatives hold potential for the development of clinical countermeasures against glioblastoma.

SLC25A22 is a novel gene for migrating partial seizures in infancy.

OBJECTIVE: To identify a genetic cause for migrating partial seizures in infancy (MPSI). METHODS: We characterized a consanguineous pedigree with MPSI and obtained DNA from affected and unaffected family members. We analyzed single nucleotide polymorphism 500K data to identify regions with evidence of linkage. We performed whole exome sequencing and analyzed homozygous variants in regions of linkage to identify a candidate gene and performed functional studies of the candidate gene SLC25A22. RESULTS: In a consanguineous pedigree with 2 individuals with MPSI, we identified 2 regions of linkage, chromosome 4p16.1-p16.3 and chromosome 11p15.4-pter. Using whole exome sequencing, we identified 8 novel homozygous variants in genes in these regions. Only 1 variant, SLC25A22 c.G328C, results in a change of a highly conserved amino acid (p.G110R) and was not present in control samples. SLC25A22 encodes a glutamate transporter with strong expression in the developing brain. We show that the specific G110R mutation, located in a transmembrane domain of the protein, disrupts mitochondrial glutamate transport. INTERPRETATION: We have shown that MPSI can be inherited and have identified a novel homozygous mutation in SLC25A22 in the affected individuals. Our data strongly suggest that SLC25A22 is responsible for MPSI, a severe condition with few known etiologies. We have demonstrated that a combination of linkage analysis and whole exome sequencing can be used for disease gene discovery. Finally, as SLC25A22 had been implicated in the distinct syndrome of neonatal epilepsy with suppression bursts on electroencephalogram, we have expanded the phenotypic spectrum associated with SLC25A22.

Pin1 inhibition activates cyclin D and produces neurodegenerative pathology.

Abnormal cell cycle events are increasingly becoming important attributes of neurodegenerative pathology. Pin1 is a crucial target of neurodegeneration in relation to its functions regarding these abnormal cell cycle events in neurons. Pin1 is majorly involved in many aspects of cell cycle regulation and it has also been suggested to have a neuroprotective function against neurodegenerative pathologies. Oxidative dysregulation of Pin1 affects not only normal tau regulation, eventually causing tangle formation, but also cell cycle regulation in neurons. Presence of cell cycle proteins has been shown in many neurodegenerative diseases. Importantly, many of these proteins have physical interactions with Pin1. Hence, understanding Pin1's role in abnormal cell cycle re-entry is critical in terms of finding new approaches for the future therapeutic options treating neurodegenerative pathologies. Here, we show that inhibition of Pin1 by its selective inhibitor juglone leads to up-regulation of cyclinD1, phospho-tau, and caspase 3, producing apoptosis in cultured rat hippocampal neurons. We also observed axonal retraction with a change in sub-cellular localizations of cyclins. Therefore, Pin1 dysregulation, in relation to its role in cell cycle regulation in neurons, may have profound effects in the progression of neurodegenerative pathology, making it a possible crucial target behind many neurodegenerative diseases.

High angiogenic potential in an in vivo rat corneal model is associated with shorter disease-free survival in low-grade oligodendrogliomas.

This study aimed to examine the association between time to tumor recurrence, angiogenic potential and tumor contrast-enhancement. Tumor samples were taken from 20 patients with low-grade oligodendroglioma and examined for their angiogenic potential using an in vivo rat corneal model of angiogenesis. Patients were evaluated for tumor contrast enhancement prior to surgical excision using MRI and they were followed for tumor recurrence. Patients who had tumors without contrast enhancement had longer disease-free survival (median time to tumor recurrence, 72 months) compared to those who had tumors with contrast enhancement (median, 42 months; p=0.0068). Based on corneal angiogenesis assay results, a high angiogenic potential was associated with a significantly shorter disease-free survival. Our findings suggest that radiological contrast enhancement and a high angiogenic potential based on an in vivo corneal angiogenesis assay were related to a shorter disease-free survival. This might have important prognostic implications in patients with low-grade oligodendrogliomas.