Microtubule depolymerization in Caenorhabditis elegans touch receptor neurons reduces gene expression through a p38 MAPK pathway.

Microtubules are integral to neuronal development and function. They endow cells with polarity, shape, and structure, and their extensive surface area provides substrates for intracellular trafficking and scaffolds for signaling molecules. Consequently, microtubule polymerization dynamics affect not only structural features of the cell but also the subcellular localization of proteins that can trigger intracellular signaling events.

mec-15 encodes an F-box protein required for touch receptor neuron mechanosensation, synapse formation and development.

Selective protein degradation is a key regulator of neuronal development and synaptogenesis. Complexes that target proteins for degradation often contain F-box proteins. Here we characterize MEC-15, an F-box protein with WD repeats, which is required for the development and function of Caenorhabditis elegans touch receptor neurons (TRNs).

The multipurpose 15-protofilament microtubules in C. elegans have specific roles in mechanosensation.

Because microtubules perform many essential functions in neurons, delineating unique roles attributable to these organelles presents a formidable challenge. Microtubules endow neurons with shape and structure and are required for developmental processes including neurite outgrowth, intracellular transport, and synapse formation and plasticity; microtubules in sensory neurons may be required for the above processes in addition to a specific sensory function. In Caenorhabditis elegans, six touch receptor neurons (TRNs) sense gentle touch and uniquely contain 15-protofilament microtubules.

Touch sensitivity in Caenorhabditis elegans.

The nematode Caenorhabditis elegans was the first organism for which touch insensitive mutants were obtained. The study of the genes defective in these mutants has led to the identification of components of a mechanosensory complex needed for specific cells to sense gentle touch to the body. Multiple approaches using genetics, cell biology, biochemistry, and electrophysiology have characterized a channel complex, containing two DEG/ENaC pore-forming subunits and several other proteins, that transduces the touch response.

Identification of genes expressed in C. elegans touch receptor neurons.

The extent of gene regulation in cell differentiation is poorly understood. We previously used saturation mutagenesis to identify 18 genes that are needed for the development and function of a single type of sensory neuron--the touch receptor neuron for gentle touch in Caenorhabditis elegans. One of these genes, mec-3, encodes a transcription factor that controls touch receptor differentiation.

Differential gene silencing by trans-heterochromatin in Drosophila melanogaster.

The brown(Dominant) (bw(D)) allele contains a large insertion of heterochromatin leading to the trans-inactivation of the wild-type allele in bw(D)/bw(+) heterozygous flies. This silencing is correlated with the localization of bw(+) to a region of the interphase nucleus containing centric heterochromatin. We have used a series of transgene constructs inserted in the vicinity of the bw locus to demarcate both the extent of bw(D) influence along the chromosome and the relative sensitivities of various genes.