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Whole worm transcriptomics after optogenetically induced mechanical muscle stress (OptIMMuS)

ABSTRACT: Mechanical stress during muscle contraction is a constant threat to proteome integrity. Experimental systems are needed to identify proteostasis regulators that are critical under mechanical stress conditions. Although Caenorhabditis elegans combines the advantages of existing organismal and cell culture models, an inducible method to stimulate muscle contraction in large populations has been lacking. Here, we present a versatile technique called OptIMMuS (Optogenetic Induction of Mechanical Muscle Stress) to study changes in the proteostasis network associated with mechanical forces. Repeated blue light exposure of a muscle-expressed Chlamydomonas rheinhardii channelrhodopsin-2 variant leads to sustained muscle contraction and mechanical stress. OptIMMuS combined with proximity labeling and mass spectrometry identified regulators that cooperate with the myosin-directed chaperone UNC-45 in muscle proteostasis. We show in genetic epistasis and co-immunoprecipitation experiments that the E3 ligase NHL-1 interacts with UNC-45 and muscle myosin, and we provide evidence that this TRIM32 orthologue affects myosin protein levels and function.

ORGANISM(S): Caenorhabditis elegans

PROVIDER: GSE241906 | GEO | 2024/07/16

REPOSITORIES: GEO

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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:Mice were subjected to 50 eccentric contractions (EC) or 50 isometric contractions (IC) using a non-invasive model, and then sacrificed 48 hours later. RNA from the tibialis anterior of 4 animals were pooled and then split into two groups for hybridization onto two separate Affymetrix MGU74Av2 chips. Control samples were contralateral to the exercised legs, and were only subjected to enough contractions to measure isometric torque. Eccentric contractions (ECs), in which a muscle is forced to lengthen while activated, result in muscle injury and, eventually, muscle strengthening and prevention of further injury. Although the mechanical basis of eccentric contraction-induced injury has been studied in detail, muscle's biological response is less well characterized. This study presents the development of a minimally-invasive model of EC injury in the mouse, follows the time course of torque recovery after an injurious bout of ECs, and uses Affymetrix microarrays to compare the gene expression profile 48 hours after ECs to both isometrically stimulated muscles and contralateral muscles. Torque dropped by about 55% immediately after the exercise bout, and recovered to initial levels 7 days later. 36 known genes were upregulated after ECs compared to contralateral and isometrically stimulated muscles, including five muscle specific genes: muscle LIM protein (MLP), Muscle Ankyrin Repeat Proteins (MARP 1 and 2; also known as cardiac ankyrin repeat protein and Arpp/Ankrd2, respectively), Xin, and Myosin Binding Protein H. The time courses of MLP and MARP expression after the injury bout (determined by quantitative real-time polymerase chain reaction) indicate that these genes are rapidly induced, reaching a peak expression level of 6-11 times contralateral values 12-24 hours after the EC bout and returning to baseline within 72 hours. Very little gene induction was seen after either isometric activation or passive stretch, indicating that the MLP and MARP genes may play an important and specific role in the biological response of muscle to EC-induced injury. Keywords = mouse tibialis anterior eccentric contraction muscle

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Whole worm transcriptomics after optogenetically induced mechanical muscle stress (OptIMMuS)

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