Protein interaction surface of the POU transcription factor UNC-86 selectively used in touch neurons

Abstract

The Caenorhabditis elegans POU protein UNC-86 specifies the HSN motor neurons, which are required for egg-laying, and six mechanosensory neurons. To investigate how UNC-86 controls neuronal specification, we characterized two unc-86 mutants that do not respond to touch but show wild-type egg-laying behavior. Residues P145 and L195, which are altered by these mutations, are located in the POU-specific domain and abolish the physical interaction of UNC-86 with the LIM homeodomain protein, MEC-3. This results in a failure to maintain mec-3 expression and in loss of expression of the mechanosensory neuron-specific gene, mec-2. unc-86-dependent expression of genes in other neurons is not impaired. We conclude that distinct residues in the POU domain of UNC-86 are involved in modulating UNC-86 activity during its specification of different neurons. A structural model of the UNC-86 POU domain, including base pairs and amino acid residues required for MEC-3 interaction, revealed that P145 and L195 are part of a hydrophobic pocket which is similar to the OCA-B-binding domain of the mammalian POU protein, Oct-1.

Heterospecific transgenesis in Drosophila suggests that engrailed.a is regulated by POU proteins in the crustacean Sacculina carcini

“…The identification of overlapping binding sites for Engrailed and Nubbin in the Sacculina en.a intron suggests that Nubbin prevents the repression of the transgene by masking Engrailed sites. POU proteins have been shown to physically interact or to compete for binding with numerous transcription factors, such as bHLH/PAS (Ma et al 2000;Zelzer and Shilo 2000), steroid receptors (Prefontaine et al 1999), retinoid receptors (Kakizawa et al 1999), winged helix/forkhead proteins (Raynal et al 1998), LIM (Rohrig et al 2000), CCAAT/Enhancer binding proteins (C/EBP) (Wu et al 1997), Sox (Ambrosetti et al 2000;Botquin et al 1998;Kuhlbrodt et al 1998), and MAD . Although Nubbin has been found in a screen for transcription factors able to bind to Engrailed consensus binding sites (Kalionis and O'Farrell 1993), our work is the first report of a direct Nubbin-Engrailed interaction on the same cis-acting sequences.…”

<i>Caenorhabditis elegans</i> MPP⁺ Model of Parkinson’s Disease for High-Throughput Drug Screenings

“…This finding was further confirmed by experi-ments with strains expressing GFP in the sensory neurons AWB [25] (fig. 4C), in the serotonergic neurons [26] ( fig. 4D) or in motor neurons (data not shown).…”

“…In order to assess a potential neurotoxic effect of MPP + on neurons, different integrated transgenic strains were used to express GFP under the control of following neuron-specific promoters: cat-2 (dopaminergic neuron-specific) [23], ttx-3 (AIY neuron-specific) [24], str-1 (sensoric AWB neuron-specific) [25], and tph-1 (serotonergic neuron-specific) [26]. The GFP expression in neurons was examined with stereofluorescence microscopes (Olympus, Hamburg, Germany) using filters for excitation wavelengths from 455 to 490 nm.…”

The Snail-like CES-1 protein of C. elegans can block the expression of theBH3-only cell-death activator gene egl-1 by antagonizing the function of bHLH proteins

“…The strain carrying the integration bcIs37 V was backcrossed five times to ced-3(n717); lin-15(n765). For transformation with the Ptph-1gfp reporter, we injected lin-15(n765) animals with plasmid pBY668 (Ptph-1gfp) (Rohrig et al, 2000) (50 ng/µl) and pL15-EK (50 ng/µl). Transgenic lines were selected and maintained at 25°C.…”