Translation Factors Research Articles

Engineering a genomically recoded organism with one stop codon.

The genetic code is conserved across all domains of life, yet exceptions have revealed variations in codon assignments and associated translation factors1-3. Inspired by this natural malleability, synthetic approaches have demonstrated whole-genome replacement of synonymous codons to construct genomically recoded organisms (GROs)4,5 with alternative genetic codes. However, no efforts have fully leveraged translation factor plasticity and codon degeneracy to compress translation function to a single codon and assess the possibility of a non-degenerate code. Here we describe construction and characterization of Ochre, a GRO that fully compresses a translational function into a single codon. We replaced 1,195 TGA stop codons with the synonymous TAA in ∆TAG Escherichia coli C321.∆A4. We then engineered release factor 2 (RF2) and tRNATrp to mitigate native UGA recognition, translationally isolating four codons for non-degenerate functions. Ochre thus utilizes UAA as the sole stop codon, with UGG encoding tryptophan and UAG and UGA reassigned for multi-site incorporation of two distinct non-standard amino acids into single proteins with more than 99% accuracy. Ochre fully compresses degenerate stop codons into a single codon and represents an important step toward a 64-codon non-degenerate code that will enable precise production of multi-functional synthetic proteins with unnatural encoded chemistries and broad utility in biotechnology and biotherapeutics.

Reduced UPF1 levels in senescence impair nonsense-mediated mRNA decay

Cells regulate gene expression through various RNA regulatory mechanisms, and this regulation often becomes less efficient with age, contributing to accelerated aging and various age-related diseases. Nonsense-mediated mRNA decay (NMD), a well-characterized RNA surveillance mechanism, degrades aberrant mRNAs with premature termination codons (PTCs) to prevent the synthesis of truncated proteins. While the role of NMD in cancer and developmental and genetic diseases is well documented, its implications in human aging remain largely unexplored. This study reveals a significant decline in the levels of the protein UPF1, a key player in NMD, during cellular senescence. Additionally, NMD substrates accumulate in senescent cells, along with decreased levels of cap-binding protein 80/20 (CBP80/20)-dependent translation (CT) factors and reduced binding to active polysomes, indicating reduced efficiency of NMD. Moreover, knockdown of UPF1 in proliferating WI-38 cells induces senescence, as evidenced by increased senescence-associated β-galactosidase activity, alterations in senescence-associated molecular markers, increased endogenous γ-H2AX levels, and reduced cell proliferation. These findings suggest that the decline in UPF1 levels during cellular senescence accelerates the senescent phenotype by impairing NMD activity and the consequent accumulation of abnormal mRNA.

Girolline is a sequence context-selective modulator of eIF5A activity

Natural products have a long history of providing probes into protein biosynthesis, with many of these compounds serving as therapeutics. The marine natural product girolline has been described as an inhibitor of protein synthesis. Its precise mechanism of action, however, has remained unknown. The data we present here suggests that girolline is a sequence-selective modulator of translation factor eIF5A. Girolline interferes with ribosome-eIF5A interaction and induces ribosome stalling where translational progress is impeded, including on AAA-encoded lysine. Our data furthermore indicate that eIF5A plays a physiological role in ribosome-associated quality control and in maintaining the efficiency of translational progress. Girolline helped to deepen our understanding of the interplay between protein production and quality control in a physiological setting and offers a potent chemical tool to selectively modulate gene expression.

MCTS2 and distinct eIF2D roles in uORF-dependent translation regulation revealed by in vitro re-initiation assays.

Ribosomes scanning from the mRNA 5' cap to the start codon may initiate at upstream open reading frames (uORFs), decreasing protein biosynthesis. Termination at a uORF can lead to re-initiation, where 40S subunits resume scanning and initiate another translation event downstream. The noncanonical translation factors MCTS1-DENR participate in re-initiation at specific uORFs, but knowledge of other trans-acting factors or uORF features influencing re-initiation is limited. Here, we establish a cell-free re-initiation assay using HeLa lysates to address this question. Comparing in vivo and in vitro re-initiation on uORF-containing reporters, we validate MCTS1-DENR-dependent re-initiation in vitro. Using this system and ribosome profiling in cells, we found that knockdown of the MCTS1-DENR homolog eIF2D causes widespread gene deregulation unrelated to uORF translation, and thus distinct to MCTS1-DENR-dependent re-initiation regulation. Additionally, we identified MCTS2, encoded by an Mcts1 retrogene, as a DENR partner promoting re-initiation in vitro, providing a plausible explanation for clinical differences associated with DENR vs. MCTS1 mutations in humans.

Hypusinated and unhypusinated isoforms of the translation factor eIF5A exert distinct effects in models of pancreas development and function.

Hypusination of eukaryotic translation initiation factor 5A (eIF5A) is essential for its role in translation elongation and termination. Although the function of hypusinated eIF5A (eIF5AHyp) in cellular proliferation is well-characterized, the role of its unhypusinated form (eIF5ALys) remains unclear. We hypothesized that eIF5ALys exerts independent, negative effects on cellular replication and metabolism, distinct from the loss of eIF5AHyp. To test this hypothesis, we utilized zebrafish and mouse models with inducible knockdowns of deoxyhypusine synthase (DHPS) and eIF5A to investigate their roles in cellular growth. Gene expression analysis via RNA sequencing and morphometric measurements of pancreas and β-cell mass were performed to assess phenotypic changes and identify affected biological pathways. Loss of DHPS in zebrafish resulted in significant defects in pancreatic growth, accompanied by changes in gene expression related to mRNA translation, neurogenesis, and stress pathways. By contrast, knockdown of eIF5A had minimal impact on pancreas development, suggesting that the effects of DHPS loss are not solely due to the lack of eIF5AHyp. In mice, β cell-specific deletion of DHPS impaired β cell mass expansion and glucose tolerance, while eIF5A deletion had no statistically significant effects. These findings provide evidence for an independent role for eIF5ALys in regulating developmental and functional responses in pancreas health and disease.

The structural biology of deoxyhypusination complexes.

Deoxyhypusination is the first rate-limiting step of the unique post-translational modification-hypusination-that is catalyzed by deoxyhypusine synthase (DHS) and deoxyhypusine hydroxylase (DOHH). This modification is essential for the activation of translation factor 5A in eukaryotes (eIF5A) and Archaea (aIF5A). This perspective focuses on the structural biology of deoxyhypusination complexes in eukaryotic and archaeal organisms. Based on recently published crystal and cryogenic electron microscopy (cryo-EM) structures of deoxyhypusination complexes from three different organisms, we compare the structural features and stoichiometries of DHS-IF5A complexes across different species. We discuss conserved elements in the active site architecture and binding interfaces as well as significant differences in their stoichiometry and regulation mechanisms. The structural insights provide a comprehensive understanding of the deoxyhypusination process and highlight evolutionary adaptations across the domains of life. Future research should focus on the regulatory mechanisms governing DHS activity and the functional implications of stoichiometric variations in different organisms.

Utility of photon-counting detectors for MV-kV dual-energy computed tomography imaging.

High soft-tissue contrast imaging is essential for effective radiotherapy treatment. This could potentially be realized using both megavoltage and kilovoltage x-ray sources available on some therapy treatment systems to perform "MV-kV" dual-energy (DE) computed tomography (CT). However, noisy megavoltage images obtained with existing energy-integrating detectors (EIDs) are a limiting factor for clinical translation. We explore the potential for non-spectral photon-counting detectors (PCDs) to improve MV-kV image quality simply by equally weighting all MV photons rather than up-weighting the less informative, lower contrast high-energy photons as in an EID. Three computational methods were applied to compare non-spectral PCDs with EIDs in MV-kV DE imaging. A single-line integral estimation theory approach was used to calculate the basis material signal-to-noise ratio (SNR) of tissue (1 to 50cm) and bone (0.1 to 10cm). CT images of a tissue cylinder with seven bone inserts (densities 1.0 to ) were simulated to assess material decomposition accuracy. Multiple noisy simulations of an anthropomorphic phantom were performed to generate pixel-by-pixel noise profiles. PCDs yielded a 15% to 45% improvement in single-line integral SNR for both materials. In CT simulations, similar material decomposition accuracy was achieved, with both EIDs and PCDs slightly underestimating bone density. However, PCDs yield a higher contrast-to-noise ratio and more uniform noise texture than EIDs in virtual monoenergetic images. We demonstrate the potential for improved MV-kV DE CT imaging using non-spectral PCDs and quantify the degree of improvement in a range of object compositions. This work motivates the experimental assessment of PCDs for megavoltage imaging and the potential clinical translation of PCDs to radiotherapy imaging.

G3BP1/2-Targeting PROTAC Disrupts Stress Granules Dependent ATF4 Migracytosis as Cancer Therapy.

Stress granules (SGs) are membraneless cytoplasmic compartments that form in response to stress stimuli. In these compartments, most translation factors stall, except for activating transcription factor 4 (ATF4), which is preferentially translated to ensure cell survival under stressful conditions. Cancer cells encounter various stress conditions in the tumor microenvironment during tumorigenesis; however, how they exploit the pro-survival effects of ATF4 in SGs remains unclear. G3BP1/2 are central nodes of the SG network, regulating SG dynamics. In this study, we designed two small molecules, #129 and PROTAC (Proteolysis Targeting Chimera) degrader 129 (PT-129), which specifically target the NTF2L domain of G3BP1/2, a crucial hub for protein and RNA interactions. These compounds inhibit the formation of stress granules in stressed cells and disassemble pre-existing stress granules. Furthermore, pharmacological inhibition by PT-129 suppressed fibroblast-mediated cancer cell growth in vitro and reduced tumor growth in vivo. Mechanistically, SG facilitates the delivery of ATF4 from fibroblasts to tumor cells via migracytosis, a primary mediator of fibroblast-associated tumor growth. PT-129-mediated disassembly of stress granules disrupts ATF4 delivery, thereby preventing cancer cell proliferation. These compounds, therefore, represent powerful tools for gaining molecular insights into SGs and hold promise for cancer therapeutic interventions by modulating stress granule dynamics.

An intermediate step in bridging the gap between evidence and practice: developing and applying a methodology for “general good practices”

The gap between evidence and clinical practice has been in the focus of researches for decades. Although successful implementation means the new knowledge must work in particular environments, it doesn’t mean that the entire process should exclusively be executed by the individual institutes. This is the point where we assumed that an intermediate step, the “general good practice”, could help to ensure that translation is done in a more professional way. The development of the general good practice methodology was based on our infinitE model, which organized the factors of successful translation into an evidence-editing-embedding-effect on practice framework, using tools from the disciplines of Evidence-Based Medicine, Quality Improvement and Change Management. The methodology organised the editing and embedding part of the development into a process involving three full-day sessions carried out with different health professionals, experts and moderators. After pilot testing, it was finalized and applied to other topics as well. The methodology presented in detail in this paper, centred on flow chart, process analysis, failure mode identification and Kotter’s 8-step model. Beside the pilot topic of the institutional process of resuscitation, the methodology has also proved applicable to more than ten other topics, meaning that at least all the core elements of the proposed bundle of general good practice have been produced in the development process. Compared to the guidelines, general good practices demonstrate the evidence in operation, helping to develop workflows, responsibilities, documentation, trainings, etc. and can also be a starting point for the digitalisation of care processes. The next step is to examine how healthcare institutions can build on these in their own editing and embedding activities, and what the results will be. Further studies could explore the applicability of the development methodology in different healthcare systems or at different levels of maturity in terms of quality.

An experimental target-based platform in yeast for screening Plasmodium vivax deoxyhypusine synthase inhibitors.

The enzyme deoxyhypusine synthase (DHS) catalyzes the first step in the post-translational modification of the eukaryotic translation factor 5A (eIF5A). This is the only protein known to contain the amino acid hypusine, which results from this modification. Both eIF5A and DHS are essential for cell viability in eukaryotes, and inhibiting DHS is a promising strategy to develop new therapeutic alternatives. DHS proteins from many are sufficiently different from their human orthologs for selective targeting against infectious diseases; however, no DHS inhibitor selective for parasite orthologs has previously been reported. Here, we established a yeast surrogate genetics platform to identify inhibitors of DHS from Plasmodium vivax, one of the major causative agents of malaria. We constructed genetically modified Saccharomyces cerevisiae strains expressing DHS genes from Homo sapiens (HsDHS) or P. vivax (PvDHS) in place of the endogenous DHS gene from S. cerevisiae. Compared with a HsDHS complemented strain with a different genetic background that we previously generated, this new strain background was ~60-fold more sensitive to an inhibitor of human DHS. Initially, a virtual screen using the ChEMBL-NTD database was performed. Candidate ligands were tested in growth assays using the newly generated yeast strains expressing heterologous DHS genes. Among these, two showed promise by preferentially reducing the growth of the PvDHS-expressing strain. Further, in a robotized assay, we screened 400 compounds from the Pathogen Box library using the same S. cerevisiae strains, and one compound preferentially reduced the growth of the PvDHS-expressing yeast strain. Western blot revealed that these compounds significantly reduced eIF5A hypusination in yeast. The compounds showed antiplasmodial activity in the asexual erythrocyte stage; EC50 in high nM to low μM range, and low cytotoxicity. Our study demonstrates that this yeast-based platform is suitable for identifying and verifying candidate small molecule DHS inhibitors, selective for the parasite over the human ortholog.

METTL16 is Required for Meiotic Sex Chromosome Inactivation and DSB Formation and Recombination during Male Meiosis.

Meiosis in males is a critical process that ensures complete spermatogenesis and genetic diversity. However, the key regulators involved in this process and the underlying molecular mechanisms remain unclear. Here, we report an essential role of the m6A methyltransferase METTL16 in meiotic sex chromosome inactivation (MSCI), double-strand break (DSB) formation, homologous recombination and SYCP1 deposition during male meiosis. METTL16 depletion results in a significantly upregulated transcriptome on sex chromosomes in pachytene spermatocytes and leads to reduced DSB formation and recombination, and increased SYCP1 depositioin during the first wave of spermatogenesis. Mechanistically, in pachytene spermatocytes, METTL16 interacts with MDC1/SCML2 to coordinate DNA damage response (DDR) and XY body epigenetic modifications that establish and maintain MSCI, and in early meiotic prophase I, METTL16 regulates DSB formation and recombination by regulating protein levels of meiosis-related genes. Furthermore, multi-omics analyses reveal that METTL16 interacts with translational factors and controls m6A levels in the RNAs of meiosis-related genes (e.g., Ubr2) to regulate the expression of critical meiotic regulators. Collectively, this study identified METTL16 as a key regulator of male meiosis and demonstrated that it modulatesmeiosis by interacting with MSCI-related factors and regulating m6A levels and translational efficiency (TE) of meiosis-related genes.

Umbrella review of systematic reviews to inform the development and translation of community-based childhood obesity prevention interventions.

Community-based interventions (CBIs) can be effective and feasible for the prevention of childhood obesity. The aim of this umbrella review is to determine if systematic reviews report sufficient information to guide replication or adaptation of CBIs to a variety of contexts and aid in further development of childhood obesity prevention CBIs. Six databases were searched for systematic reviews including obesity prevention CBIs involving 0-18 year olds and reporting weight-related outcomes. Two researchers screened results. Evidence-to-decision frameworks guided which details may be required for decision-makers to design and carry-out a CBI, including information on intervention characteristics, outcome reporting and translation factors. From 3935 search results, 40 studies were included. The most frequently reported relevant pieces of information were behaviors targeted (100% of systematic reviews), intervention duration (90%) and settings involved (97.5%). Less frequently reported factors included specific actions implemented (48%), intervention intensity (30%) and organizations, or contributors involved (40%). There was a low level of reporting of equity considerations (27.5%), adverse events (20%), and costs/cost-effectiveness (17.5%). Multilevel interventions for child obesity prevention have demonstrated effectiveness, yet additional documentation of successful intervention processes is needed.

Impact of Surgical Alignment, Bone Properties, Anterior-Posterior Translation, and Implant Design Factors on Fixation in Cementless Unicompartmental Knee Arthroplasty.

Micromotion exceeding 150 μm at the implant-bone interface may prevent bone formation and limit fixation after cementless knee arthroplasty. Understanding the critical parameters impacting micromotion is required for optimal implant design and clinical performance. However, few studies have focused on unicompartmental knee arthroplasty (UKA). This study assessed the impacts of alignment, surgical, and design factors on implant-bone micromotions for a novel cementless UKA design during a series of simulated daily activities. Three finite element models that were validated for predicting micromotion of cementless total knee arthroplasty (TKA) were loaded with design-specific kinematics/loading to simulate gait (GT), deep knee bending (DKB), and stair descent (SD). The implant-bone micromotion and the porous surface area ideal for bone ingrowth were estimated and compared to quantify the impact of each factor. Overall, the peak tray-bone micromotions were consistently found at the lateral aspect of the tibial baseplate and were consistently higher than the femoral micromotions. The femoral micromotion was insensitive to almost all the factors studied, and the porous area favorable for bone ingrowth was no less than 93%. For a medial uni, implanting the tray 1 mm medially or the femoral component 1 mm laterally reduced the tibial micromotion by 19.3% and 26.3%, respectively. Differences in tray-bone micromotion due to bone moduli were up to 59.8%. A 5 mm more posterior femoral translation increased the tray-bone micromotion by 35.8%. The presence of the tray keel prevented the spread of the micromotion and increased the overall porous surface area, but also increased peak micromotion. The tray peg and the femoral anterior peg had little impact on the micromotion of their respective implants. In conclusion, centralizing the load transfer to minimize tibial tray applied moment and optimizing the fixation features to minimize micromotion are consistent themes for improving cementless fixation in UKA. Perturbation of femoral-bone alignment may be preferred as it would not create under/overhang on the tibia.

Nutritional intervention to enhance recovery after arthroscopic knee surgery in adults: a randomized controlled pilot trial

BackgroundEssential amino acid (EAA) and omega-3 fatty acid ingestion independently attenuate leg skeletal muscle disuse atrophy in uninjured persons. However, no data exist regarding the effectiveness of combined EAA and omega-3 fatty acid ingestion to mitigate skeletal muscle disuse atrophy in response to anterior cruciate ligament reconstruction (ACLR) surgery. This pilot trial will explore the feasibility of recruitment and retention of ACLR outpatients from a single center across 18 months to consume either a combination of omega-3 fatty acids and EAAs, or a placebo control, for 4 weeks before and 2 weeks after surgery.MethodsThirty adult (≥ 18 years old) ACLR outpatients will be recruited for this single center, double-blind, two-arm randomized controlled feasibility pilot trial. Participants will consume either 5 g⋅day−1 of omega-3 fatty acids (fish oil) and 40 g⋅day−1 of EAAs or 5 g⋅day−1 of a control fatty acid mixture (safflower oil) and 40 g⋅day−1 of non-essential amino acids (NEAAs). Fatty acid supplements will be consumed 4 weeks before and for 2 weeks after ACLR surgery, whereas the EAAs and NEAAs will be consumed 1 week before and for 2 weeks after ACLR surgery. The primary outcomes are feasibility of recruitment and retention, with the goal to recruit 30 outpatients across 18 months and retain 22 participants upon completion of the study protocol following 12 weeks of data collection. These results will be reported using descriptive statistics, along with reasons and timepoints for study dropout. Secondary exploratory outcomes will be reported using inferential statistics for purposes of hypothesis generation and elucidation of mechanistic targets for future work; no inferences to clinical efficacy will be made. These outcomes include integrated rates of skeletal muscle protein synthesis, skeletal muscle protein content and expression of translation factors, skeletal muscle and erythrocyte phospholipid composition, and measures of skeletal muscle mass, strength, and power.ImpactThis work will set the foundation for a future randomized controlled trial powered to detect an effect of EAA + omega-3 fatty acid intake on skeletal muscle size or function in response to ACLR surgery.Trial registrationClinicalTrials.gov, NCT06233825. Registered 31 January 2024. https://clinicaltrials.gov/study/NCT06233825?term=NCT06233825&rank=1

EIF5A controls mitoprotein import by relieving ribosome stalling at TIM50 translocase mRNA.

Efficient import of nuclear-encoded proteins into mitochondria is crucial for proper mitochondrial function. The conserved translation factor eIF5A binds ribosomes, alleviating stalling at polyproline-encoding sequences. eIF5A impacts mitochondrial function across species, though the precise molecular mechanism is unclear. We found that eIF5A depletion in yeast reduces the translation and levels of the TCA cycle and oxidative phosphorylation proteins. Loss of eIF5A causes mitoprotein precursors to accumulate in the cytosol and triggers a mitochondrial import stress response. We identify an essential polyproline protein as a direct target of eIF5A: the mitochondrial inner membrane protein and translocase component Tim50. Thus, eIF5A controls mitochondrial protein import by alleviating ribosome stalling along Tim50 mRNA at the mitochondrial surface. Removal of polyprolines from Tim50 partially rescues the mitochondrial import stress response and translation of oxidative phosphorylation genes. Overall, our findings elucidate how eIF5A impacts the mitochondrial function by promoting efficient translation and reducing ribosome stalling of co-translationally imported proteins, thereby positively impacting the mitochondrial import process.

Radiographic Predictors of Lateral Translation in Patients With Residual Adolescent Idiopathic Scoliosis and Thoracolumbar/Lumbar Curves: A Focus on L3 Lateral Translation

BackgroundPatients with residual adolescent idiopathic scoliosis (AIS) and thoracolumbar/lumbar (TL/L) curves may present with progression after cessation of growth, with lateral translation as a major risk factor. Nonetheless, radiographic predictors and underlying mechanisms remain indefinite. This study aimed to determine these radiographic predictors and structural mechanisms in patients with residual AIS. MethodsRadiographic and clinical data were collected from 45 consecutive patients with preoperative residual AIS and TL/L Cobb angle >40° who subsequently underwent corrective surgery at our institution. Lateral translation was defined as intervertebral slippage ≥6 mm on computed tomography. Statistical analyses included Student’s t-test, Pearson’s correlation coefficients, receiver operating characteristic (ROC) curve analysis, and multivariate logistic regression analysis. ResultsOut of 45 patients, 3 were male, whereas 42 were female, with a mean age of 40.6±17.4 years. L3 slippage was observed in 21 patients, resulting in the categorization into the slippage and non-slippage cohorts. Multivariate logistic regression analysis revealed statistically significant disparities in the bilateral facet angles, facet joint opening, and facet joint vacuum phenomenon between the two cohorts. The ROC analysis determined a 20.5° cut-off value for predicting L3 slippage. In the non-slippage cohort, a strong correlation was particularly observed between L3 slippage and L2–L3 bridging. ConclusionFacet joint instability, L4 tilt ≥20.5°, and L3 cranial vertebral bridging are predictive radiographic factors for L3 lateral translation in patients with residual AIS. Thus, patients exhibiting these characteristics require consistent follow-up or early surgical intervention before lateral translation occurs.

Lessons learned from COVID-19 modelling efforts for policy decision-making in lower- and middle-income countries

IntroductionThe COVID-19 pandemic had devastating health and socioeconomic effects, partly due to policy decisions to mitigate them. Little evidence exists of approaches that guided decisions in settings with limited pre-pandemic...

The Drosophila ribonucleoprotein Clueless is required for ribosome biogenesis in vivo

As hubs of metabolism, mitochondria contribute critical processes to coordinate and optimize energy and intermediate metabolites. Drosophila Clueless (Clu) and vertebrate CLUH are ribonucleoproteins critical for supporting mitochondrial function yet do so in multiple ways. Clu/CLUH bind mRNAs and CLUH regulates mRNA localization and translation of mRNAs encoding proteins destined for mitochondrial import. In addition, Clu associates with ribosomal proteins and translation factors, yet whether it is required for fundamental ribosome function in vivo is not clear. In this study, we examine the Clu interactome and probe Clu’s requirement in ribosome biogenesis. We previously showed that Clu associates with ribosomal proteins. In this study, we extend these observations to show that clu null mutants display a significant decrease in overall protein synthesis. In addition, Clu associates with ribosomal proteins in an mRNA-independent manner, suggesting Clu’s core ribosomal function may be separate from its role in localizing and translating specific mRNAs. We find that Clu is present in the nucleus and associates with the ribosomal RNA (rRNA) processing protein fibrillarin but, surprisingly, that processed rRNA products are normal in the absence of Clu. Furthermore, Clu loss does not affect ribosomal protein levels, but does result in a decrease in 40S and 60S ribosomal subunits abundance. Together, these results demonstrate that Clu is present in the nucleus and required for 40S and 60S biogenesis and global translation in vivo. These results highlight the multifaceted role of Clu in supporting cell function through regulation of mRNA encoding mitochondrial proteins and ribosome biogenesis.

The mysteries of LETM1 pleiotropy

LETM1 is a nuclear-encoded protein located in the inner mitochondrial membrane, playing a critical role in regulating mitochondrial cation and volume homeostasis. However, numerous studies on functional features, molecular interactions, and disease-associated effects of LETM1 revealed that LETM1 is also involved in other metabolic functions including glucose utilization, mitochondrial DNA and ribosome organization, cristae architecture and respiratory complex stability. Undisputedly, osmoregulatory processes are essential for mitochondrial functionality, but the pleiotropic aspects of LETM1 challenges us to understand the core function of LETM1, which still remains elusive. In this review, we provide an overview of the current knowledge and latest developments regarding the activities involving LETM1. We highlight various findings that offer different functional perspectives and ideas on the core function of LETM1. Specifically, we emphasize data supporting LETM1's role as a mitochondrial translational factor, K+/H+ exchanger, or Ca2+/H+ exchanger, along with recent findings on its interaction with ATAD3A and TMBIM5. We also present the severe clinical implications of LETM1 deficiency. Finally, we discuss emerging questions raised by the different views on LETM1, which need to be addressed to guide future research directions and ultimately resolve the function of this essential protein and develop targeted therapeutic strategies.

Decreased mitochondrial translation confers 3,3′-Diindolylmethane resistance to Schizosaccharomyces pombe

3,3′-Diindolylmethane (DIM), a compound derived from natural fruits and vegetables, is widely recognized for its anti-cancer activity. However, its action mechanisms remain ambiguous. In this study, to study the molecular mechanism of 3,3′-Diindolylmethane, we identified a novel mutation in the gene of mitochondrial translation elongation factor EF-Ts (tsf1+), a key factor in mitochondrial protein translation, that conferred DIM resistance to Schizosaccharomyces pombe. The tsf1Δ also conferred DIM resistance. Decreased mitochondrial translation was found to be responsible for conferring DIM resistance to Schizosaccharomyces pombe, as the cells gained DIM resistance after treatment with chloramphenicol, a specific mitochondrial translation inhibitor. Notably, tsf1Δ conferred DIM resistance in the absence of either autophagy-related protein, Atg7, or nuclear envelope protein, Lem2, two proteins that have been reported to be required for cell survival in the presence of DIM. Overall, this study revealed novel biological functions of DIM and highlighted its potential as an anti-cancer agent.