We studied the ability of heat shock, DnaJ-like-1 (HSJ1) proteins (which contain DnaJ and ubiquitin-interacting motifs) to reduce polyglutamine-mediated inclusion formation. The experiments demonstrated that expression of heat shock protein 70 (hsp70), hsp40, HSJ1a, and HSJ1b significantly reduced protein inclusion formation in a model of spinal and bulbar muscular atrophy (SBMA). HSJ1a also mediated a significant decrease in the number of inclusions formed in a primary neuronal model of protein aggregation. Studies to elucidate the mechanisms underlying these reductions showed that hsp70 and hsp40 increased chaperone-mediated refolding. In contrast, expression of HSJ1 proteins did not promote chaperone activity but caused an increase in ubiquitylation. Furthermore, HSJ1a was associated with a ubiquitylated luciferase complex, and in the presence of HSJ1a but not an HSJ1a UIM mutant (HSJ1a-deltaUIM) there was a reduction in luciferase protein levels. Together these results show that HSJ1 proteins mediated an increase in target protein degradation via the ubiquitin-proteasome system (UPS). We also found that the expression of HSJ1a significantly decreased the number of neurons containing inclusions in an in vivo model of polyglutamine disease. These findings indicate that targeted modification of the UPS to facilitate degradation of misfolded proteins may represent a highly effective therapeutic avenue for the treatment of polyglutamine disease.

Evidence suggests that the acquisition of recognition memory depends upon CREB-dependent long-lasting changes in synaptic plasticity in the perirhinal cortex. The CREB-responsive microRNA miR-132 has been shown to regulate synaptic transmission and we set out to investigate a role for this microRNA in recognition memory and its underlying plasticity mechanisms. To this end we mediated the specific overexpression of miR-132 selectively in the rat perirhinal cortex and demonstrated impairment in short-term recognition memory. This functional deficit was associated with a reduction in both long-term depression and long-term potentiation. These results confirm that microRNAs are key coordinators of the intracellular pathways that mediate experience-dependent changes in the brain. In addition, these results demonstrate a role for miR-132 in the neuronal mechanisms underlying the formation of short-term recognition memory.

Background: “Mirrored” or complementary mammalian miRNAs have been predicted but none have yet been characterized.Results: miR-3120 and miR-214 are produced from the same intronic locus; miR-3120 regulates heat shock cognate protein 70 (Hsc70) and auxilin expression and vesicle uncoating.Conclusion: miR-3120 is a mirror miRNA regulating endocytic function.Significance: Mirror miRNAs are important mammalian gene regulatory units, and many more remain to be found and characterized.

In recent years, the development of powerful viral gene transfer techniques has greatly facilitated the study of gene function. This review summarises some of the viral delivery systems routinely used to mediate gene transfer into cell lines, primary cell cultures and in whole animal models. The systems described were originally discussed at a 1-day European Tissue Culture Society (ETCS-UK) workshop that was held at University College London on 1st April 2009. Recombinant-deficient viral vectors (viruses that are no longer able to replicate) are used to transduce dividing and post-mitotic cells, and they have been optimised to mediate regulatable, powerful, long-term and cell-specific expression. Hence, viral systems have become very widely used, especially in the field of neurobiology. This review introduces the main categories of viral vectors, focusing on their initial development and highlighting modifications and improvements made since their introduction. In particular, the use of specific promoters to restrict expression, translational enhancers and regulatory elements to boost expression from a single virion and the development of regulatable systems is described.

The anti‐apoptotic effects of heat‐shock protein (Hsp70) were assessed in SCG neurones following nerve growth factor (NGF) withdrawal. The results showed that the virally mediated expression of Hsp70 mirrored the effects of the c‐Jun‐N‐terminal kinase (JNK) binding domain (JBD) of JNK interacting protein (an inhibitor of JNK and c‐Jun activation) and suppressed the phosphorylation of c‐Jun. Preventing c‐Jun transcriptional activity subsequently led to reduced cytochrome c release and prevented caspase activation as indicated by a decrease in poly (ADP‐ribose) polymerase‐1 (PARP) cleavage. Together, these results show that Hsp70 is a highly effective inhibitor of apoptosis in sympathetic neurones and that it mediates this effect primarily by suppressing c‐Jun transcriptional signalling.