Colorectal cancer cells display chaperone dependency for the unconventional prefoldin URI1

Chaperone dependency of cancer cells is an emerging trait that relates to the need of transformed cells to cope with the various stresses associated with the malignant state. URI1 (unconventional prefoldin RPB5 interactor 1) encodes a member of the prefoldin (PFD) family of molecular chaperones that acts as part of a heterohexameric PFD complex, the URI1 complex (URI1C), to promote assembly of multiprotein complexes involved in cell signaling and transcription processes. Here, we report that human colorectal cancer (CRCs) cell lines demonstrate differential dependency on URI1 and on the URI1 partner PFD STAP1 for survival, suggesting that this differential vulnerability of CRC cells is directly linked to URI1C chaperone function. Interestingly, in URI1-dependent CRC cells, URI1 deficiency is associated with non-genotoxic p53 activation and p53-dependent apoptosis. URI1-independent CRC cells do not exhibit such effects even in the context of wildtype p53. Lastly, in tumor xenografts, the conditional depletion of URI1 in URI1-dependent CRC cells was, after tumor establishment, associated with severe inhibition of subsequent tumor growth and activation of p53 target genes. Thus, a subset of CRC cells has acquired a dependency on the URI1 chaperone system for survival, providing an example of 'non-oncogene addiction' and vulnerability for therapeutic targeting.

Production of fosmid genomic libraries optimized for liquid culture recombineering and cross-species transgenesis

Genomic DNA libraries are a valuable source of large constructs that can contain all the regulatory elements necessary for recapitulating wild-type gene expression when introduced into animal genomes as a transgene. Such clones can be directly used in complementation studies. In combination with recombineering manipulation, the tagged genomic clones can serve as faithful in vivo gene activity reporters that enable studies of tissue specificity of gene expression, subcellular protein localization, and affinity purification of complexes. We present a detailed protocol for generating an unbiased genomic library in a custom pFlyFos vector that is optimized for liquid culture recombineering manipulation and site-specific transgenesis of fosmid-size loci across different Drosophila species. The cross-species properties of the library can be used, for example, to establish the specificity of RNAi phenotypes or to selectively introgress specific genomic loci among different Drosophila species making it an ideal tool for experimental evolutionary studies. The FlyFos system can be easily adapted to other organisms.

Development dysphasia and electroencephalographic abnormalities

Seven patients, six boys and one girl, ranging in age from 2 years 7 months to 5 years 6 months at first contact, presented with severe language delay and dysphasic errors. They were found to have markedly abnormal EEGs despite the fact that only two of the children had had febrile seizures. The EEG abnormalities consisted to spike-wave or sharp wave discharges in focal or bilateral synchronous fashion, and were not affected by anticonvulsants. The children had normal motor development and no dysmorphic features. Results of neurological examinations were normal. CT and isotope scans were unrevealing. Intelligence, measured by a non-verbal scale, was normal. The authors suggest that an electrophysiological disturbance was the underlying cause of both the language deficits and the EEG abnormalities. The remarkably frequent occurrence of postmaturity (five of the seven cases) suggests that perinatal events may be an etiological factor.