bims-musmir 2024-10-20 papers

bims-musmir

Biomed News

on microRNAs in muscle

Issue of 2024–10–20
eleven papers selected by
Katarzyna Agnieszka Goljanek-Whysall, University of Galway

Integrative study of skeletal muscle mitochondrial dysfunction in a murine pancreatic cancer-induced cachexia model.
Exercise, disease state and sex influence the beneficial effects of Fn14-depletion on survival and muscle pathology in the SOD1G93A amyotrophic lateral sclerosis (ALS) mouse model.
Differentially expressed lncRNAs in SOD1G93A mice skeletal muscle: H19, Myhas and Neat1 as potential biomarkers in amyotrophic lateral sclerosis.
Network-based modelling reveals cell-type enriched patterns of non-coding RNA regulation during human skeletal muscle remodelling.
Persistent Fatigue, Weakness, and Aberrant Muscle Mitochondria in Survivors of Critical COVID-19.
Acute contractile activity induces the activation of the mitochondrial integrated stress response and the transcription factor ATF4.
Skeletal muscle fibre type-dependent effects of atorvastatin on the PI3K/Akt/mTOR signalling pathway and atrophy-related genes in rats.
The Oldest of Old Male C57B/6J Mice Are Protected from Sarcopenic Obesity: The Possible Role of Skeletal Muscle Protein Kinase B Expression.
Respiratory pathology in the TDP-43 transgenic mouse model of amyotrophic lateral sclerosis.
Depletion of loss-of-function germline mutations in centenarians reveals longevity genes.
Resistance to Cry14A family Bacillus thuringiensis crystal proteins in Caenornabditis elegans operates via the nhr-31 transcription factor and vacuolar-type ATPase pathway.

Elife. 2024 Oct 18. pii: RP93312. [Epub ahead of print]13

Integrative study of skeletal muscle mitochondrial dysfunction in a murine pancreatic cancer-induced cachexia model.

Tristan Gicquel, Fabio Marchiano, Gabriela Reyes-Castellanos, Stephane Audebert, Luc Camoin, Bianca H Habermann, Benoit Giannesini, Alice Carrier.

  Pancreatic ductal adenocarcinoma (PDAC), the most common pancreatic cancer, is a deadly cancer, often diagnosed late and resistant to current therapies. PDAC patients are frequently affected by cachexia characterized by muscle mass and strength loss (sarcopenia) contributing to patient frailty and poor therapeutic response. This study assesses the mechanisms underlying mitochondrial remodeling in the cachectic skeletal muscle, through an integrative exploration combining functional, morphological, and omics-based evaluation of gastrocnemius muscle from KIC genetically engineered mice developing autochthonous pancreatic tumor and cachexia. Cachectic PDAC KIC mice exhibit severe sarcopenia with loss of muscle mass and strength associated with reduced muscle fiber's size and induction of protein degradation processes. Mitochondria in PDAC atrophied muscles show reduced respiratory capacities and structural alterations, associated with deregulation of oxidative phosphorylation and mitochondrial dynamics pathways. Beyond the metabolic pathways known to be altered in sarcopenic muscle (carbohydrates, proteins, and redox), lipid and nucleic acid metabolisms are also affected. Although the number of mitochondria per cell is not altered, mitochondrial mass shows a twofold decrease and the mitochondrial DNA threefold, suggesting a defect in mitochondrial genome homeostasis. In conclusion, this work provides a framework to guide toward the most relevant targets in the clinic to limit PDAC-induced cachexia.

Keywords:  cachexia; cancer biology; energy metabolism; mitochondria; mouse; muscle wasting; pancreatic cancer

DOI:  https://doi.org/10.7554/eLife.93312
Skelet Muscle. 2024 Oct 14. 14(1): 23

Exercise, disease state and sex influence the beneficial effects of Fn14-depletion on survival and muscle pathology in the SOD1G93A amyotrophic lateral sclerosis (ALS) mouse model.

Gareth Hazell, Eve McCallion, Nina Ahlskog, Emma R Sutton, Magnus Okoh, Emad I H Shaqoura, Joseph M Hoolachan, Taylor Scaife, Sara Iqbal, Amarjit Bhomra, Anna J Kordala, Frederique Scamps, Cedric Raoul, Matthew J A Wood, Melissa Bowerman.

   BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a devastating and incurable neurodegenerative disease. Accumulating evidence strongly suggests that intrinsic muscle defects exist and contribute to disease progression, including imbalances in whole-body metabolic homeostasis. We have previously reported that tumour necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) and fibroblast growth factor inducible 14 (Fn14) are significantly upregulated in skeletal muscle of the SOD1G93A ALS mouse model. While antagonising TWEAK did not impact survival, we did observe positive effects in skeletal muscle. Given that Fn14 has been proposed as the main effector of the TWEAK/Fn14 activity and that Fn14 can act independently from TWEAK in muscle, we suggest that manipulating Fn14 instead of TWEAK in the SOD1G93A ALS mice could lead to differential and potentially improved benefits.
METHODS: We thus investigated the contribution of Fn14 to disease phenotypes in the SOD1G93A ALS mice. To do so, Fn14 knockout mice (Fn14-/-) were crossed onto the SOD1G93A background to generate SOD1G93A;Fn14-/- mice. Investigations were performed on both unexercised and exercised (rotarod and/or grid test) animals (wild type (WT), Fn14-/-, SOD1G93A and SOD1G93A;Fn14-/-).
RESULTS: Here, we firstly confirm that the TWEAK/Fn14 pathway is dysregulated in skeletal muscle of SOD1G93A mice. We then show that Fn14-depleted SOD1G93A mice display increased lifespan, myofiber size, neuromuscular junction endplate area as well as altered expression of known molecular effectors of the TWEAK/Fn14 pathway, without an impact on motor function. Importantly, we also observe a complex interaction between exercise (rotarod and grid test), genotype, disease state and sex that influences the overall effects of Fn14 deletion on survival, expression of known molecular effectors of the TWEAK/Fn14 pathway, expression of myosin heavy chain isoforms and myofiber size.
CONCLUSIONS: Our study provides further insights on the different roles of the TWEAK/Fn14 pathway in pathological skeletal muscle and how they can be influenced by age, disease, sex and exercise. This is particularly relevant in the ALS field, where combinatorial therapies that include exercise regimens are currently being explored. As such, a better understanding and consideration of the interactions between treatments, muscle metabolism, sex and exercise will be of importance in future studies.

Keywords:  Amyotrophic lateral sclerosis; Exercise; Fn14; Metabolism; Sex; Skeletal muscle; TWEAK

DOI:  https://doi.org/10.1186/s13395-024-00356-0
Open Biol. 2024 Oct;14(10): 240015

Differentially expressed lncRNAs in SOD1G93A mice skeletal muscle: H19, Myhas and Neat1 as potential biomarkers in amyotrophic lateral sclerosis.

Tresa López-Royo, Laura Moreno-Martínez, Pilar Zaragoza, Alberto García-Redondo, Raquel Manzano, Rosario Osta.

  Amyotrophic lateral sclerosis (ALS) is a devastating neuromuscular disease characterized by progressive motor function and muscle mass loss. Despite extensive research in the field, the underlying causes of ALS remain incompletely understood, contributing to the absence of specific diagnostic and prognostic biomarkers and effective therapies. This study investigates the expression of long-non-coding RNAs (lncRNAs) in skeletal muscle as a potential source of biomarkers and therapeutic targets for the disease. The expression profiles of 12 lncRNAs, selected from the literature, were evaluated across different disease stages in tissue and muscle biopsies from the SOD1G93A transgenic mouse model of ALS. Nine out of the 12 lncRNAs were differentially expressed, with Pvt1, H19 and Neat1 showing notable increases in the symptomatic stages of the disease, and suggesting their potential as candidate biomarkers to support diagnosis and key players in muscle pathophysiology in ALS. Furthermore, the progression of Myhas and H19 RNA levels across disease stages correlated with longevity in the SOD1G93A animal model, effectively discriminating between long- and short-term survival individuals, thereby highlighting their potential as prognostic indicators. These findings underscore the involvement of lncRNAs, especially H19 and Myhas, in ALS pathophysiology, offering novel insights for diagnostic, prognostic and therapeutic targets.

Keywords:  amyotrophic lateral sclerosis; biomarkers; diagnosis; long-non-coding RNAs (lncRNAs); prognosis

DOI:  https://doi.org/10.1098/rsob.240015
bioRxiv. 2024 Oct 09. pii: 2024.08.11.606848. [Epub ahead of print]

Network-based modelling reveals cell-type enriched patterns of non-coding RNA regulation during human skeletal muscle remodelling.

Jonathan C Mcleod, Changhyun Lim, Tanner Stokes, Jalil-Ahmad Sharif, Vagif Zeynalli, Lucas Wiens, Alysha C D'Souza, Lauren Colenso-Semple, James McKendry, Robert W Morton, Cameron J Mitchell, Sara Y Oikawa, Claes Wahlestedt, J Paul Chapple, Chris McGlory, James A Timmons, Stuart M Phillips.

A majority of human genes produce non-protein-coding RNA (ncRNA), and some have roles in development and disease. Neither ncRNA nor human skeletal muscle is ideally studied using short-read sequencing, so we used a customised RNA pipeline and network modelling to study cell-type specific ncRNA responses during muscle growth at scale. We completed five human resistance-training studies (n=144 subjects), identifying 61% who successfully accrued muscle-mass. We produced 288 transcriptome-wide profiles and found 110 ncRNAs linked to muscle growth in vivo, while a transcriptome-driven network model demonstrated interactions via a number of discrete functional pathways and single-cell types. This analysis included established hypertrophy-related ncRNAs, including CYTOR - which was leukocyte-associated (FDR = 4.9 x10 -7 ). Novel hypertrophy-linked ncRNAs included PPP1CB-DT (myofibril assembly genes, FDR = 8.15 x 10 -8 ), and EEF1A1P24 and TMSB4XP8 (vascular remodelling and angiogenesis genes, FDR = 2.77 x 10 -5 ). We also discovered that hypertrophy lncRNA MYREM shows a specific myonuclear expression pattern in vivo . Our multi-layered analyses established that single-cell-associated ncRNA are identifiable from bulk muscle transcriptomic data and that hypertrophy-linked ncRNA genes mediate their association with muscle growth via multiple cell types and a set of interacting pathways.
One Sentence Summary: We used an optimised transcriptomic strategy to identify a set of ncRNA genes regulated during skeletal muscle hypertrophy in one hundred and forty-four people, with network modelling and spatial imaging providing biological context.

DOI: https://doi.org/10.1101/2024.08.11.606848
Crit Care Explor. 2024 Oct 01. 6(10): e1164

Persistent Fatigue, Weakness, and Aberrant Muscle Mitochondria in Survivors of Critical COVID-19.

Kirby P Mayer, Ahmed Ismaeel, Anna G Kalema, Ashley A Montgomery-Yates, Melissa K Soper, Philip A Kern, Jonathan D Starck, Stacey A Slone, Peter E Morris, Esther E Dupont-Versteegden, Kate Kosmac.

OBJECTIVES: Persistent skeletal muscle dysfunction in survivors of critical illness due to acute respiratory failure is common, but biological data elucidating underlying mechanisms are limited. The objective of this study was to elucidate the prevalence of skeletal muscle weakness and fatigue in survivors of critical illness due to COVID-19 and determine if cellular changes associate with persistent skeletal muscle dysfunction.
DESIGN: A prospective observational study in two phases: 1) survivors of critical COVID-19 participating in physical outcome measures while attending an ICU Recovery Clinic at short-term follow-up and 2) a nested cohort of patients performed comprehensive muscle and physical function assessments with a muscle biopsy; data were compared with non-COVID controls.
SETTING: ICU Recovery Clinic and clinical laboratory.
PATIENTS/SUBJECTS: Survivors of critical COVID-19 and non-COVID controls.
INTERVENTIONS: None.
MEASUREMENTS AND MAIN RESULTS: One hundred twenty patients with a median of 56 years old (interquartile range [IQR], 42-65 yr old), 43% female, and 33% individuals of underrepresented race attended follow-up 44 ± 17 days after discharge. Patients had a median Acute Physiology and Chronic Health Evaluation-II score of 24.0 (IQR, 16-29) and 98 patients (82%) required mechanical ventilation with a median duration of 14 days (IQR, 9-21 d). At short-term follow-up significant physical dysfunction was observed with 93% of patients reporting generalized fatigue and performing mean 218 ± 151 meters on 6-minute walk test (45% ± 30% of predicted). Eleven patients from this group agreed to participate in long-term assessment and muscle biopsy occurring a mean 267 ± 98 days after discharge. Muscle tissue from COVID exhibited a greater abundance of M2-like macrophages and satellite cells and lower activity of mitochondrial complex II and complex IV compared with controls.
CONCLUSIONS: Our findings suggest that aberrant repair and altered mitochondrial activity in skeletal muscle associates with long-term impairments in patients surviving an ICU admission for COVID-19.

DOI: https://doi.org/10.1097/CCE.0000000000001164
J Appl Physiol (1985). 2024 Oct 17.

Acute contractile activity induces the activation of the mitochondrial integrated stress response and the transcription factor ATF4.

Victoria C Sanfrancesco, David A Hood.

  Skeletal muscle relies on mitochondria to produce energy and support its metabolic flexibility. The function of the mitochondrial pool is regulated by quality control (MQC) processes. The integrated stress response (ISR), a MQC pathway, is activated in response to various cellular stressors. The transcription factor ATF4, the main effector of the ISR, ameliorates cellular stress by upregulating protective genes, such as CHOP and ATF5. Recent literature has shown that the ISR is activated upon mitochondrial stress, however, whether this includes acute exercise-induced stress is poorly defined. To investigate this, a mouse in situ hindlimb protocol was utilized to acutely stimulate muscles at 0.25, 0.5 and 1 tetanic contraction/per second for 9 mins, followed by a 1-hour recovery period. CAMKII and JNK2 were robustly activated 6-fold immediately following the protocol. ISR activation, denoted as the ratio of phosphorylated to total-eIF2a protein levels, was also elevated following recovery. Downstream, contractile activity induced an increase in the nuclear localization of ATF4. Robust 2-fold increases in the mRNA expression of ATF4 and CHOP were also observed following the recovery period. Changes in ATF4 mRNA were independent of transcriptional activation, as assessed using an ATF4 promoter-reporter plasmid. Instead, mRNA decay assays revealed an increase in ATF4 mRNA stability post-contractile activity, as a result of enhanced stabilization by the RNA binding protein, HuR. Thus, acute contractile activity is sufficient to induce mitochondrial stress and activate the ISR, corresponding to the induction of ATF4 with potential consequences for mitochondrial phenotype adaptations in response to repeated exercise.

Keywords:  Adaptations; Exercise; Mitochondrial Biogenesis; Skeletal Muscle; eIF2α

DOI:  https://doi.org/10.1152/japplphysiol.00307.2024
Mol Biol Rep. 2024 Oct 17. 51(1): 1062

Skeletal muscle fibre type-dependent effects of atorvastatin on the PI3K/Akt/mTOR signalling pathway and atrophy-related genes in rats.

Anna Gawedzka, Malgorzata Knapik-Czajka, Jagoda Drag, Malgorzata Belczyk, Edyta Radwanska, Dariusz Adamek.

   BACKGROUND: One of the probable causes of statin myotoxicity is an imbalance between protein synthesis and degradation. These processes are regulated by the PI3K/Akt/mTOR pathway and the ubiquitin‒proteasome system (UPS). The aim of this study was to assess whether the effects of atorvastatin on PI3K/Akt/mTOR pathway downstream proteins, the FoxO3a transcription factor and the UPS genes, i.e., MuRF-1 and MAFbx, depend on muscle fibre type.
METHODS AND RESULTS: Atorvastatin (50 mg/kg) was administered to Wistar rats. The levels of selected PI3K/Akt/mTOR pathway proteins were assayed via Western blotting, whereas MuRF-1, MAFbx and FoxO3a mRNA levels were measured using reverse transcription quantitative polymerase chain reaction (RT‒qPCR). Gomöri trichrome staining was performed to assess skeletal muscle pathology. A decrease in the P-Akt/Akt ratio was observed in the gastrocnemius muscle (MG), whereas an increase in the P-Akt/Akt ratio was observed in the soleus muscle (SOL). FoxO3a gene expression increased in the SOL and extensor digitorum longus (EDL) muscles. MuRF-1 gene expression increased in the MG, and MAFbx expression increased in the EDL. No histopathological changes were observed in any of the tested muscles.
CONCLUSIONS: In the absence of overt muscle damage, atorvastatin decreased the P-Akt/Akt ratio in the MG, indicating an increase in inactive Akt. Consistent with the decrease in Akt activation, rpS6 phosphorylation decreased. In SOL, atorvastatin increased the P-Akt/Akt ratio, indicating Akt activation. P-FoxO3a and the P-FoxO3a/FoxO3a ratio increased, suggesting that FoxO3a inactivation occurred. Moreover, in the SOL, atorvastatin did not affect the expression of atrophy-related genes. These findings indicate that atorvastatin has no adverse effect on the Akt pathway in the SOL. Our results showed that the effects of atorvastatin on the Akt signalling pathway and atrophy-related gene expression depend on muscle type.

Keywords:  Akt pathway; Atorvastatin; Atrophy-related genes; Skeletal muscle fibres

DOI:  https://doi.org/10.1007/s11033-024-10005-w
Int J Mol Sci. 2024 Sep 24. pii: 10278. [Epub ahead of print]25(19):

The Oldest of Old Male C57B/6J Mice Are Protected from Sarcopenic Obesity: The Possible Role of Skeletal Muscle Protein Kinase B Expression.

Thomas H Reynolds, Noa Mills, Dakembay Hoyte, Katy Ehnstrom, Alex Arata.

  The impact of aging on body composition and glucose metabolism is not well established in C57BL/6J mice, despite being a common pre-clinical model for aging and metabolic research. The purpose of this study was to examine the effect of advancing age on body composition, in vivo glucose metabolism, and skeletal muscle AKT expression in young (Y: 4 months old, n = 7), old (O: 17-18 months old, n = 10), and very old (VO: 26-27 month old, n = 9) male C57BL/6J mice. Body composition analysis, assessed by nuclear magnetic resonance, demonstrated O mice had a significantly greater fat mass and body fat percentage when compared to Y and VO mice. Furthermore, VO mice had a significantly greater lean body mass than both O and Y mice. We also found that the VO mice had greater AKT protein levels in skeletal muscle compared to O mice, an observation that explains a portion of the increased lean body mass in VO mice. During glucose tolerance (GT) testing, blood glucose values were significantly lower in the VO mice when compared to the Y and O mice. No age-related differences were observed in insulin tolerance (IT). We also assessed the glucose response to AMPK activation by 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR). The change in blood glucose following AICAR administration was significantly reduced in VO mice compared to Y and AG mice. Our findings indicate that lean body mass and AKT2 protein expression in muscle are significantly increased in VO mice compared to O mice. The increase in AKT2 likely plays a role in the greater lean body mass observed in the oldest of old mice. Finally, despite the increased GT, VO mice appear to be resistant to AMPK-mediated glucose uptake.

Keywords:  aging; body composition; glucose metabolism; protein kinase B; skeletal muscle

DOI:  https://doi.org/10.3390/ijms251910278
Front Physiol. 2024 ;15 1430875

Respiratory pathology in the TDP-43 transgenic mouse model of amyotrophic lateral sclerosis.

Debolina D Biswas, Ronit Sethi, Yochebed Woldeyohannes, Evelyn R Scarrow, Léa El Haddad, Jane Lee, Mai K ElMallah.

  Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease that results in death within 2-5 years of diagnosis. Respiratory failure is the most common cause of death in ALS. Mutations in the transactive response DNA binding protein 43 (TDP-43) encoded by the TARDBP gene are associated with abnormal cellular aggregates in neurons of patients with both familial and sporadic ALS. The role of these abnormal aggregates on breathing is unclear. Since respiratory failure is a major cause of death in ALS, we sought to determine the role of TDP-43 mutations on the respiratory motor unit in the Prp-hTDP-43A315T mouse model - a model that expresses human TDP-43 containing the A315T mutation. We assessed breathing using whole-body plethysmography, and investigated neuropathology in hypoglossal and phrenic respiratory motor units. Postmortem studies included quantification of hypoglossal and putative phrenic motor neurons, activated microglia and astrocytes in respiratory control centers, and assessment of hypoglossal and phrenic nerves of TDP43A315T mice. The male TDP43A315T mice display an early onset of rapid progression of disease, and premature death (less than 15 weeks) compared to control mice and compared to female TDP43A315T mice who die between 20 and 35 weeks of age. The TDP43A315T mice have progressive and profound breathing deficits at baseline and during a respiratory challenge. Histologically, hypoglossal and putative phrenic motor neurons of TDP43A315T mice are decreased and have increased microglial and astrocyte activation, indicating pronounced neurodegeneration and neuroinflammation. Further, there is axonopathy and demyelination in the hypoglossal and phrenic nerve of TDP43A315T mice. Thus, the TDP-43A315T mice have significant respiratory pathology and neuropathology, which makes them a useful translatable model for the study of novel therapies on breathing in ALS.

Keywords:  TDP-43 (43kda TAR DNA binding protein); amyotrophic lateral sclerosis; breathing abnormalities; motor neurodegeneration; neuroinflammation; phrenic and hypoglossal nerve; respiration

DOI:  https://doi.org/10.3389/fphys.2024.1430875
Nat Commun. 2024 Oct 19. 15(1): 9030

Depletion of loss-of-function germline mutations in centenarians reveals longevity genes.

Kejun Ying, José P Castro, Anastasia V Shindyapina, Alexander Tyshkovskiy, Mahdi Moqri, Ludger J E Goeminne, Sofiya Milman, Zhengdong D Zhang, Nir Barzilai, Vadim N Gladyshev.

While previous studies identified common genetic variants associated with longevity in centenarians, the role of the rare loss-of-function (LOF) mutation burden remains largely unexplored. Here, we investigated the burden of rare LOF mutations in Ashkenazi Jewish individuals from the Longevity Genes Project and LonGenity study cohorts using whole-exome sequencing data. We found that centenarians had a significantly lower burden (11-22%) of LOF mutations compared to controls. Similar effects were also observed in their offspring. Gene-level burden analysis identified 35 genes with depleted LOF mutations in centenarians, with 14 of these validated in the UK Biobank. Mendelian randomization and multi-omic analyses on these genes identified RGP1, PCNX2, and ANO9 as longevity genes with consistent causal effects on multiple aging-related traits and altered expression during aging. Our findings suggest that a protective genetic background, characterized by a reduced burden of damaging variants, contributes to exceptional longevity, likely acting in concert with specific protective variants to promote healthy aging.

DOI: https://doi.org/10.1038/s41467-024-52967-2
PLoS Pathog. 2024 Oct 18. 20(10): e1012611

Resistance to Cry14A family Bacillus thuringiensis crystal proteins in Caenornabditis elegans operates via the nhr-31 transcription factor and vacuolar-type ATPase pathway.

YouMie Kim, Thanh-Thanh Nguyen, Daniel J Durning, Takao Ishidate, Ozkan Aydemir, Craig C Mello, Yan Hu, Theodore W Kahn, Raffi V Aroian.

Bacillus thuringiensis (Bt) has been successfully used commercially for more than 60 years for biocontrol of insect pests. Since 1996, transgenic plants expressing Bt crystal (Cry) proteins have been used commercially to provide protection against insects that predate on corn and cotton. More recently, Bt Cry proteins that target nematodes have been discovered. One of these, Cry14Ab, has been expressed in transgenic soybean plants and found to provide significant protection against the soybean cyst nematode, Heterodera glycines. However, to date there has been no description of high-level resistance to any Cry14A family protein in nematodes. Here, we describe forward genetic screens to identify such mutants using the nematode Caenorhabditis elegans. Although non-conditional screens failed to identify highly resistant C. elegans, a conditional (temperature-sensitive) genetic screen identified one mutant, bre-6(ye123) (for Bt protein resistant), highly resistant to both Cry14Aa and Cry14Ab. The mutant comes at a high fitness cost, showing significant delays in growth and development and reduced fecundity. bre-6(ye123) hermaphrodites are only weakly resistant to copper intoxication, indicating that the mutant is not highly resistant to all insults. Backcrossing-whole genome sequencing was used to identify the gene mutated in ye123 as the nuclear hormone receptor nhr-31. RNAi, DNA rescue, and CRISPR analyses confirm that resistance to Cry14Aa intoxication in bre-6(ye123) is due to mutation of nhr-31 and was renamed nhr-31(ye123). As predicted for a mutation in this gene, nhr-31(ye123) animals showed significantly reduced expression of most of the subunits of the C. elegans vacuolar ATPase (vATPase). Mutants in the vATPase subunits unc-32 and vha-7 also show resistance to Cry14Aa and/or Cry14Ab. These data demonstrate that nhr-31 and the vATPase play a significant role in the intoxication of C. elegans by Cry14A family proteins, that reduction in vATPase levels result in high resistance to Cry14A family proteins, and that such resistance comes at a high fitness cost. Based on the relative difficulty of finding resistant mutants and the fitness cost associated with the vATPase pathway, our data suggest that transgenic Cry14Ab plants may hold up well to resistance by nematode parasites.

DOI: https://doi.org/10.1371/journal.ppat.1012611