The Danubian Principalities.The frontier Lands of the Christ

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Nociceptor-Enriched Genes Required for Normal Thermal Nociception

Here, we describe a targeted reverse genetic screen for thermal nociception genes in Drosophila larvae. Using laser capture microdissection and microarray analyses of nociceptive and non-nociceptive neurons, we identified 275 nociceptor-enriched genes. We then tested the function of the enriched genes with nociceptor-specific RNAi and thermal nociception assays. Tissue-specific RNAi targeted against 14 genes caused insensitive thermal nociception while targeting of 22 genes caused hypersensitive thermal nociception. Previously uncategorized genes were named for heat resistance (i.e., boilerman, fire dancer, oven mitt, trivet, thawb, and bunker gear) or heat sensitivity (firelighter, black match, eucalyptus, primacord, jet fuel, detonator, gasoline, smoke alarm, and jetboil). Insensitive nociception phenotypes were often associated with severely reduced branching of nociceptor neurites and hyperbranched dendrites were seen in two of the hypersensitive cases. Many genes that we identified are conserved in mammals

Ethics Report on Interspecies Somatic Cell Nuclear Transfer Research

This report considers whether research involving the creation of human-animal interspecies somatic cell nuclear transfer (iSCNT) embryos raises new ethical issues, and if so, whether it requires additional or special criteria and oversight distinct from research on human-animal chimeras

Balboa Binds to Pickpocket In Vivo and Is Required for Mechanical Nociception in Drosophila Larvae

SummaryThe Drosophila gene pickpocket (ppk) encodes an ion channel subunit of the degenerin/epithelial sodium channel (DEG/ENaC) family [1]. PPK is specifically expressed in nociceptive, class IV multidendritic (md) neurons and is functionally required for mechanical nociception responses [2, 3]. In this study, in a genome-wide genetic screen for other ion channel subunits required for mechanical nociception, we identify a gene that we name balboa (also known as CG8546, ppk26) [4]. Interestingly, the balboa locus encodes a DEG/ENaC ion channel subunit highly similar in amino acid sequence to PPK [5]. Moreover, laser-capture isolation of RNA from larval neurons and microarray analyses reveal that balboa is also highly enriched in nociceptive neurons. The requirement for Balboa and PPK in mechanical nociception behaviors and their specific expression in larval nociceptors led us to hypothesize that these DEG/ENaC subunits form an ion channel complex in vivo. In nociceptive neurons, Balboa::GFP proteins distribute uniformly throughout dendrites but remarkably localize to discrete foci when ectopically expressed in other neuron subtypes (where PPK is not expressed). Indeed, ectopically coexpressing ppk transforms this punctate Balboa::GFP expression pattern to the uniform distribution observed in its native cell type. Furthermore, ppk-RNAi in class IV neurons alters the broad Balboa::GFP pattern to a punctate distribution. Interestingly, this interaction is mutually codependent as balboa-RNAi eliminates Venus::PPK from the sensory dendrites of nociceptors. Finally, using a GFP-reconstitution approach in transgenic larvae, we directly detect in vivo physical interactions among PPK and Balboa subunits. Combined, our results indicate a critical mechanical nociception function for heteromeric PPK and Balboa channels in vivo

Folate regulation of axonal regeneration in the rodent central nervous system through DNA methylation

The folate pathway plays a crucial role in the regeneration and repair of the adult CNS after injury. Here, we have shown in rodents that such repair occurs at least in part through DNA methylation. In animals with combined spinal cord and sciatic nerve injury, folate-mediated CNS axon regeneration was found to depend on injury-related induction of the high-affinity folate receptor 1 (Folr1). The activity of folate was dependent on its activation by the enzyme dihydrofolate reductase (Dhfr) and a functional methylation cycle. The effect of folate on the regeneration of afferent spinal neurons was biphasic and dose dependent and correlated closely over its dose range with global and gene-specific DNA methylation and with expression of both the folate receptor Folr1 and the de novo DNA methyltransferases. These data implicate an epigenetic mechanism in CNS repair. Folic acid and possibly other nontoxic dietary methyl donors may therefore be useful in clinical interventions to promote brain and spinal cord healing. If indeed the benefit of folate is mediated by epigenetic mechanisms that promote endogenous axonal regeneration, this provides possible avenues for new pharmacologic approaches to treating CNS injuries