Project description:We performed RNA-seq to quantify gene expression changes in adult worms upon knockdown of transcription factor unc-62/Homothorax. unc-62 is a developmental regulator that binds proximal to age-regulated transcripts and modulates lifespan. In the intestine (in which tissue-specific unc-62 knockdown increases lifespan), we identify multiple effects of unc-62 knockdown linked to extension of longevity. First, unc-62 RNAi decreases the expression of yolk proteins (vitellogenins) that aggregate in the body cavity and become toxic in old age. Second, unc-62 RNAi results in a broad increase in expression of intestinal genes that typically decrease expression with age, suggesting that unc-62 activity balances intestinal resource allocation between yolk protein expression and fertility on the one hand and somatic functions on the other.
Project description:To gain molecular insights on how UNC-49 regulates C. elegans innate immunity, we used RNA sequencing to profile gene expression in unc-49(e407) animals relative to wild-type animals with or without P. aeruginosa(PA14) infection. We found that UNC-49 suppresses the expression of insulin pathway genes, and lack of UNC-49-mediated suppression in unc-49(e407) animals contributes to their improved survival against P. aeruginosa infection.
Project description:Myosin motors are critical for diverse motility functions ranging from cytokinesis and endocytosis to muscle contraction. The UNC-45 chaperone controls myosin function mediating the folding, assembly, and degradation of the muscle protein. Here, we analyze the molecular mechanism of UNC-45 as a hub in myosin quality control. We show that UNC-45 forms discrete complexes with folded and unfolded myosin, forwarding them to downstream chaperones and E3 ligases. Structural analysis of a minimal chaperone:substrate complex reveals that UNC-45 binds to a conserved FX3HY motif in the myosin motor domain. Disrupting the observed interface by mutagenesis prevents myosin maturation leading to protein aggregation in vivo. We also show that a mutation in the FX3HY motif linked to the Freeman Sheldon Syndrome impairs UNC-45 assisted folding, reducing the level of functional myosin. These findings demonstrate that a faulty myosin quality control is a critical yet unexplored cause of human myopathies.
Project description:This project includes two proximity labeling experiments, one to establish the vicinity of UNC-45 under non-stress conditions and one to examine changes in the vicinity of UNC-45 under optogenetically induced mechanical muscle stress. The first non-stress experiment consists of 15 samples after biotin-streptavidin pull-down in 5 replicates of 3 conditions (3 transgenic C. elegans strains). Transgenic C. elegans strains expressing the mutant BirA biotin ligases miniTurbo and TurboID in body wall muscle cells were used to compare a proximity-labeled strain expressing an UNC-45-miniTurbo-2xHA fusion protein in the muscle cells (PP3135 unc-119(ed4)III; hhIs241[unc-54p::unc-45::miniTurbo::2xHA; unc-119(+)]) with a strain expressing the biotin ligase TurboID-2xHA without fusion protein in muscle cells (PP3138 unc-119(ed4)III; hhIs242[unc-54p::TurboID::2xHA; unc-119(+)]) to find transient interactors of the myosin chaperone UNC-45 in muscle. As a control, we included a strain expressing a transgenic UNC-45-FLAG protein in the body wall muscle (PP1017 unc-119(ed4)III; hhIs84[unc-119(+); unc-54p::unc-45::FLAG]). Biotinylated proteins in 2.5 mg lysates of these strains were pulled down with streptavidin sepharose beads and identified by mass spectrometry. The second mechanical stress experiment consists of 10 samples after biotin-streptavidin pull-down in 5 replicates of 2 conditions. A transgenic C. elegans strain expressing the biotin ligase miniTurbo fused to UNC-45 in body wall muscle cells was crossed with a transgenic strain expressing the optogenetic channelrhodopsin mutant ChR2(C128S;H134R)-FLAG in body wall muscle cells (PP3358 hhIs241[unc-54p::unc-45::miniTurbo::2xHA; unc-119(+)]; hhIs251[myo-3p::ChR2(C128S,H134R)-FLAG::unc-54 3'UTR, Cbrunc-119(+)]). The latter transgene is used to contract the worms’ muscles by blue light illumination to induce mechanical muscle stress. The optogenetic channel is activated by adding the cofactor all-trans retinal (ATR) to its food source E. coli OP50. In this experiment, we compared proximity-labeling in the UNC-45-miniTurbo-2xHA expressing strain under conditions with ATR (L+, treatment, contraction) with proximity-labeling in the UNC-45-miniTurbo-2xHA expressing strain under conditions without ATR (L-, control, no contraction) to find transient interactors of the candidate UNC-45 in muscle under mechanical stress. Biotinylated proteins in 2.5 mg of lysates of these strains were pulled down using streptavidin sepharose beads and identified by mass spectrometry.
Project description:In Caenorhabditis elegans, VA and VB motor neurons arise as lineal sisters but synapse with different interneurons to regulate locomotion. VA-specific inputs are defined by the UNC-4 homeoprotein and its transcriptional corepressor, UNC-37/Groucho, which function in the VAs to block the creation of chemical synapses and gap junctions with interneurons normally reserved for VBs. To reveal downstream genes that control this choice, we have employed a cell-specific microarray strategy that has now identified unc-4-regulated transcripts. One of these genes, ceh-12, a member of the HB9 family of homeoproteins, is normally restricted to VBs. We show that expression of CEH-12/HB9 in VA motor neurons in unc-4 mutants imposes VB-type inputs. Thus, this work reveals a developmental switch in which motor neuron input is defined by differential expression of transcription factors that select alternative presynaptic partners. The conservation of UNC-4, HB9, and Groucho expression in the vertebrate motor circuit argues that similar mechanisms may regulate synaptic specificity in the spinal cord.