Mitochondrial Ribosomal Subunit Research Articles

The Downregulation of CRIF1 Exerts Antitumor Effects Partially via TP53-Induced Glycolysis and Apoptosis Regulator Induction in BT549 Breast Cancer Cells.

Mitochondrial oxidative phosphorylation (OXPHOS) has been exploited as a therapeutic target in cancer treatments because of its crucial role in tumorigenesis. CR6-interacting factor 1 (CRIF1), a mitochondrial ribosomal subunit protein, is essential for the regulation of mitochondrial OXPHOS capacity. However, the mechanism of CRIF1 in triple-negative breast cancer (TNBC) cells remains unclear. We showed that the downregulation of CRIF1 reduced cell proliferation in the TNBC cell lines MDA-MB-468, MDA-MB-231, and, especially, BT549. In addition, wound scratch and Transwell assays showed that CRIF1 deficiency inhibited the migration and invasion of BT549 cells. CRIF1 downregulation resulted in the suppression of mitochondrial bioenergetics in BT549 cells, specifically affecting the inhibition of OXPHOS complexes I and II. This was evidenced by a decrease in the mitochondrial oxygen consumption rate and the depolarization of the mitochondrial membrane potential. Damage to mitochondria resulted in a lower adenosine triphosphate level and an elevated production of mitochondrial reactive oxygen species. In addition, CRIF1 deficiency decreased hypoxia-inducible factor 1α accumulation, NADPH synthesis, and TP53-induced glycolysis and apoptosis regulator (TIGAR) expression in BT549 cells. These events contributed to G0/G1-phase cell cycle inhibition and the upregulation of the cell cycle protein markers p53, p21, and p16. Transfection with a TIGAR overexpression plasmid reversed these effects and prevented CRIF1 downregulation-induced proliferation and migration reduction. These results indicate that blocking mitochondrial OXPHOS synthesis via CRIF1 may have a therapeutic antitumor effect in BT549 TNBC cells.

Abstract 4123630: MRPL44 Plays an Important Role in Cardiac Hypertrophy and Function

Background: Mitochondrial ribosomal large subunit 44 (MRPL44) knockout mice were embryonic lethal, for which mutations are known to cause mitochondrial infantile cardiomyopathy and hypertrophic cardiomyopathy. However, it remains unknown how MRPL44 contributes to cardiac function and hypertrophy. Aims: Our aim is to investigate the effect of MRPL44 haploinsufficiency in mice. Methods: MRPL44 haploinsufficient (MRPL44 +/- ) mice were generated. Mineralocorticoid receptor-associated hypertension mice were induced in MRPL44 +/- and wild-type (WT, MRPL44 +/+ ) mice with subcutaneous infusion of aldosterone(Aldo) and 8% NaCl food for 4 weeks after uninephrectomy. Systolic blood pressure was measured by tail cuffs every week. WB, qPCR, cardiac echo, and histological examinations were performed. RNA sequencing analysis, electron microscopy examinations and mitochondrial activity assay were performed to find differences between MRPL44 +/- and MRPL44 +/+ mice. Results: MRPL44 haploinsufficient mice spontaneously developed left ventricular hypertrophy. Heart rate, blood pressure, and cardiac systolic function were normal in MRPL44 haploinsufficient mice. MRPL44 was decreased about to 70% in MRPL44 haploinsufficient mice and mitochondrial arrangement were impaired in electron microscopic analysis. After Aldo treatment, blood pressure elevation were similar, however, MRPL44 haploinsufficient mice developed left ventricular systolic dysfunction and dilation compared with MRPL44 +/+ mice. WB showed mitochondrial electron transport chain protein complex IV expression was significantly decreased. Furthermore, mitochondrial activity assay showed MRPL44 haploinsufficient mice had a significant reduction in complex IV activity, whereas complex I and II activity were similar to MRPL44 +/+ mice. RNA sequencing analysis showed the significant changes in the expression of ribosomal subunits coded by nucleus in addition to mitochondrial ribosomal subunits. These results indicate MRPL44 plays an important role in the cardiac function of mitochondrial electron transport chain protein complexes via the expression of ribosomal protein subunits coded by both nucleus and mitochondria. Conclusion: MRPL44 haploinsufficient mice spontaneously develop left ventricular hypertrophy and shows systolic dysfunction after aldosterone treatment accompanied with oxidative phosphorylation enzyme dysfunction.

MRPL44 haploinsufficient mouse spontaneously develops hypertrophic cardiomyopathy and shows systolic dysfunction after aldosterone treatment

Abstract Introduction It has been recently reported there are big differences in pathophysiological and molecular phenotypes in mouse and human hypertrophic cardiomyopathy. These differences are observed all in terms of myocyte redox, mitochondrial number and respiration, mitochondrial reactive oxygen species generation and Ca2+ handling. Therefore we should search for molecules to be able to induce similar phenotype and molecular signaling both in mice and human. Mitochondrial ribosomal large subunit 44 (MRPL44) knockout mice were embryonic lethal, for which mutations are known to cause mitochondrial infantile cardiomyopathy and hypertrophic cardiomyopathy. Purpose Our purpose is to investigate the effect of MRPL44 haploinsufficiency in mice. Methods MRPL44 haploinsufficient (MRPL44+/-) mice were generated. Mineralocorticoid receptor-associated hypertension mice were induced in MRPL44+/- and wild-type (WT, MRPL44+/+) mice with subcutaneous infusion of aldosterone(Aldo) and 8% NaCl food for 4 weeks after uninephrectomy. Systolic blood pressure was measured by tail cuffs every week. WB, qPCR, cardiac echo, and histological examinations were performed. RNA sequencing analysis, electron microscopy examinations and mitochondrial activity assay were performed to find differences between MRPL44+/- and MRPL44+/+ mice. Results MRPL44 haploinsufficient mice spontaneously developed left ventricular hypertrophy in 6 weeks old. Heart rate, blood pressure, and cardiac systolic function were normal in MRPL44 haploinsufficient mice. MRPL44 was decreased about to 70% in MRPL44 haploinsufficient mice and mitochondrial arrangement were impaired in electron microscopic analysis. After Aldo treatment, blood pressure elevation were similar, however, MRPL44 haploinsufficient mice developed left ventricular systolic dysfunction and dilation compared with MRPL44+/+ mice. WB showed mitochondrial electron transport chain protein complex IV expression was significantly decreased. Furthermore, mitochondrial activity assay showed MRPL44 haploinsufficient mice had a significant reduction in complex IV activity, whereas complex I and II activity were similar to MRPL44+/+ mice. RNA sequencing analysis showed the significant changes in the expression of ribosomal subunits coded by nucleus in addition to mitochondrial ribosomal subunits. These results indicate MRPL44 plays an important role in the cardiac function of mitochondrial electron transport chain protein complexes via the expression of ribosomal protein subunits coded by both nucleus and mitochondria. Conclusions MRPL44 haploinsufficient mice spontaneously develop left ventricular hypertrophy and shows systolic dysfunction after aldosterone treatment accompanied with oxidative phosphorylation enzyme dysfunction.

Biallelic variants in MRPL49 cause variable clinical presentations, including sensorineural hearing loss, leukodystrophy, and ovarian insufficiency.

Combined oxidative phosphorylation deficiency (COXPD) is a rare multisystem disorder which is clinically and genetically heterogeneous. Genome sequencing identified biallelic MRPL49 variants in individuals from five unrelated families with presentations ranging from Perrault syndrome (primary ovarian insufficiency and sensorineural hearing loss) to severe childhood onset of leukodystrophy, learning disability, microcephaly and retinal dystrophy. Complexome profiling of fibroblasts from affected individuals revealed reduced levels of the small and, a more pronounced reduction of, the large mitochondrial ribosomal subunits. There was no evidence of altered mitoribosomal assembly. The reductions in levels of OXPHOS enzyme complexes I and IV are consistent with a form of COXPD associated with biallelic MRPL49 variants, expanding the understanding of how disruption of the mitochondrial ribosomal large subunit results in multi-system phenotypes.

Arabidopsis Pentatricopeptide Repeat Protein GEND2 Participates in Mitochondrial RNA Editing.

In Arabidopsis, RNA editing alters more than 500 cytidines (C) to uridines (U) in mitochondrial transcripts, a process involving the family of pentatricopeptide repeat (PPR) proteins. Here, we report a previously uncharacterized mitochondrial PLS-type PPR protein, GEND2, which functions in the mitochondrial RNA editing. The T-DNA insertion in the 5'-untranslated region of GEND2, referred to as gend2-1, results in defective root development compared to wild-type (WT) plants. A comprehensive examination of mitochondrial RNA-editing sites revealed a significant reduction in the gend2-1 mutant compared to WT plants, affecting six specific mitochondrial RNA editing sites, notably within the mitochondrial genes CcmFn-1, RPSL2 and ORFX. These genes encode critical components of cytochrome protein maturation pathway, mitochondrial ribosomal subunit and twin arginine translocation subunits, respectively. Further analysis of the transcriptional profile of the gend2-1 mutant and WT revealed a striking induction of expression in a cluster of genes associated with mitochondrial dysfunction and regulated by ANAC017, a key regulator coordinating organelle functions and stress responses. Intriguingly, the gend2-1 mutation activated an ANAC017-dependent signaling aimed at countering cell wall damage induced by cellulose synthase inhibitors, as well as an ANAC017-independent pathway that retarded root growth under normal condition. Collectively, our findings identify a novel mitochondrial PLS-type PPR protein GEND2, which participates in the editing of six specific mitochondrial RNA editing sites. Furthermore, the gend2-1 mutation triggers two distinct pathways in plants: an ANAC017-dependent pathway and ANAC017-independent pathway.

The phenotypic spectrum of PTCD3 deficiency.

The PTCD3 gene product (protein PTCD3 or MRPS39) forms the entry channel of the mitochondrial small ribosomal subunit and binds to single-stranded mRNA. Here, we expand on the clinical manifestations of PTCD3 pathogenic variants by describing an early-onset patient with Leigh-like syndrome and two patients with milder form of disease, with combined oxidative phosphorylation deficiency. A 34-year-old male and his 33-year-old sister both have horizontal nystagmus, pronounced rough tremor, truncal ataxia, dysmetria, spasticity and hyperreflexia. The basal respiration rate decreased significantly for the male patient and his mother (p < 0.0001) compared to the controls. The whole genome sequencing analysis revealed two heterozygous variants in the PTCD3: c.1182T>A, p.(Tyr394Ter) and c.805C>T, p.(His269Tyr). Tyr394Ter variant ablates the C-terminal half of the protein, including a significant portion of the central fold. In silico modelling for the variant His269Tyr shows that the inclusion of the slightly larger tyrosine sidechain is well tolerated, with no significant change in either the position or the movement of the surrounding area. The third case is a 9-year-old boy, who has a global developmental delay, central hypotonia, hyperreflexia and abnormal MRI. PTCD3 pathogenic variant c.538+4A>G was identified by whole exome sequencing. To test the variant's effect on splicing, an RT-PCR experiment was performed, which revealed skipping of an out-of-frame exon 7.

Characterization of Mitoribosomal Small Subunit unit genes related immune and pharmacogenomic landscapes in renal cell carcinoma.

Mitoribosomes are essential for the production of biological energy. The Human Mitoribosomal Small Subunit unit (MRPS) family, responsible for encoding mitochondrial ribosomal small subunits, is actively engaged in protein synthesis within the mitochondria. Intriguingly, MRPS family genes appear to play a role in cancer. A multistep process was employed to establish a risk model associated with MRPS genes, aiming to delineate the immune and pharmacogenomic landscapes in clear cell renal cell carcinoma (ccRCC). MRPScores were computed for individual patients to assess their responsiveness to various treatment modalities and their susceptibility to different therapeutic targets and drugs. While MRPS family genes have been implicated in various cancers as oncogenes, our findings reveal a contrasting tumor suppressor role for MRPS genes in ccRCC. Utilizing an MRPS-related risk model, we observed its excellent prognostic capability in predicting survival outcomes for ccRCC patients. Remarkably, the subgroup with high MRPS-related scores (MRPScore) displayed poorer prognosis but exhibited a more robust response to immunotherapy. Through in silico screening of 2183 drug targets and 1646 compounds, we identified two targets (RRM2 and OPRD1) and eight agents (AZ960, carmustine, lasalocid, SGI-1776, AZD8055_1059, BPD.00008900_1998, MK.8776_2046, and XAV939_1268) with potential therapeutic implications for high-MRPScore patients. Our study represents the pioneering effort in proposing that molecular classification, diagnosis, and treatment strategies can be formulated based on MRPScores. Indeed, a high MRPScore profile appears to elevate the risk of tumor progression and mortality, potentially through its influence on immune regulation. This suggests that the MRPS-related risk model holds promise as a prognostic predictor and may offer novel insights into personalized therapeutic strategies.

A viable hypomorphic mutation in the mitochondrial ribosome subunit, MRPS-31, exhibits mitochondrial dysfunction in C. elegans.

The mitochondrial ribosome (mitoribosome) translates mitochondrial genome encoded proteins essential for cellular energy production. Given this critical role, defects in the mitoribosome can cause mitochondrial stress and manifest as multisystemic diseases. In a screen for unique activators of the mitochondrial unfolded protein response (UPR mt ) in Caenorhabditis elegans , we recovered a strain harboring a missense mutation in the gene encoding mitochondrial ribosome protein S31 ( MRPS-31 )-a component of the mitoribosome small subunit. Herein, we confirm causality of the mrps-31 allele and characterize its induction of UPR mt and impact on organismal development, providing a valuable model for further study of the mitoribosome.

Research on genetic diversity and population structure of Capitulum mitella in the Western Taiwan Strait based on mitochondrial 16S rRNA sequences

Abstract Capitulum mitella is an important species in the intertidal ecosystem and in the economy in China. This study explored the genetic diversity and population structure of C. mitella using mitochondrial 16S ribosomal subunit (16S rRNA) gene sequences. The researchers sequenced a 527 bp fragment of 16S rRNA from 390 samples collected from six localities along Western Taiwan Strait and identified 45 distinct haplotypes with an average haplotype diversity (h) of 0.451 and an average nucleotide diversity (π) of 0.00124. The pairwise statistics and AMOVA indicated a lack of significant population structure. The results indicated a recent expansion of the population of C. mitella in the study area. This expansion, combined with the species’ high dispersal capabilities, limited physical barriers, and the influence of oceanic currents, may be the factors contributing to its current phylogeographic structure. This study provides particularly important information for managing and protecting the resources of C. mitella in Southern China.

Origin of minicircular mitochondrial genomes in red algae

Eukaryotic organelle genomes are generally of conserved size and gene content within phylogenetic groups. However, significant variation in genome structure may occur. Here, we report that the Stylonematophyceae red algae contain multipartite circular mitochondrial genomes (i.e., minicircles) which encode one or two genes bounded by a specific cassette and a conserved constant region. These minicircles are visualized using fluorescence microscope and scanning electron microscope, proving the circularity. Mitochondrial gene sets are reduced in these highly divergent mitogenomes. Newly generated chromosome-level nuclear genome assembly of Rhodosorus marinus reveals that most mitochondrial ribosomal subunit genes are transferred to the nuclear genome. Hetero-concatemers that resulted from recombination between minicircles and unique gene inventory that is responsible for mitochondrial genome stability may explain how the transition from typical mitochondrial genome to minicircles occurs. Our results offer inspiration on minicircular organelle genome formation and highlight an extreme case of mitochondrial gene inventory reduction.

Pbp1 associates with Puf3 and promotes translation of its target mRNAs involved in mitochondrial biogenesis.

Pbp1 (poly(A)-binding protein-binding protein 1) is a cytoplasmic stress granule marker that is capable of forming condensates that function in the negative regulation of TORC1 signaling under respiratory conditions. Polyglutamine expansions in its mammalian ortholog ataxin-2 lead to spinocerebellar dysfunction due to toxic protein aggregation. Here, we show that loss of Pbp1 in S. cerevisiae leads to decreased amounts of mRNAs and mitochondrial proteins which are targets of Puf3, a member of the PUF (Pumilio and FBF) family of RNA-binding proteins. We found that Pbp1 supports the translation of Puf3-target mRNAs in respiratory conditions, such as those involved in the assembly of cytochrome c oxidase and subunits of mitochondrial ribosomes. We further show that Pbp1 and Puf3 interact through their respective low complexity domains, which is required for Puf3-target mRNA translation. Our findings reveal a key role for Pbp1-containing assemblies in enabling the translation of mRNAs critical for mitochondrial biogenesis and respiration. They may further explain prior associations of Pbp1/ataxin-2 with RNA, stress granule biology, mitochondrial function, and neuronal health.

Deficiency of the mitochondrial ribosomal subunit, MRPL50, causes autosomal recessive syndromic premature ovarian insufficiency

Premature ovarian insufficiency (POI) is a common cause of infertility in women, characterised by amenorrhea and elevated FSH under the age of 40 years. In some cases, POI is syndromic in association with other features such as sensorineural hearing loss in Perrault syndrome. POI is a heterogeneous disease with over 80 causative genes known so far; however, these explain only a minority of cases. Using whole-exome sequencing (WES), we identified a MRPL50 homozygous missense variant (c.335T > A; p.Val112Asp) shared by twin sisters presenting with POI, bilateral high-frequency sensorineural hearing loss, kidney and heart dysfunction. MRPL50 encodes a component of the large subunit of the mitochondrial ribosome. Using quantitative proteomics and western blot analysis on patient fibroblasts, we demonstrated a loss of MRPL50 protein and an associated destabilisation of the large subunit of the mitochondrial ribosome whilst the small subunit was preserved. The mitochondrial ribosome is responsible for the translation of subunits of the mitochondrial oxidative phosphorylation machinery, and we found patient fibroblasts have a mild but significant decrease in the abundance of mitochondrial complex I. These data support a biochemical phenotype associated with MRPL50 variants. We validated the association of MRPL50 with the clinical phenotype by knockdown/knockout of mRpL50 in Drosophila, which resulted abnormal ovarian development. In conclusion, we have shown that a MRPL50 missense variant destabilises the mitochondrial ribosome, leading to oxidative phosphorylation deficiency and syndromic POI, highlighting the importance of mitochondrial support in ovarian development and function.

Yet Another Similarity between Mitochondrial and Bacterial Ribosomal Small Subunit Biogenesis Obtained by Structural Characterization of RbfA from S. aureus.

Ribosome biogenesis is a complex and highly accurate conservative process of ribosomal subunit maturation followed by association. Subunit maturation comprises sequential stages of ribosomal RNA and proteins' folding, modification and binding, with the involvement of numerous RNAses, helicases, GTPases, chaperones, RNA, protein-modifying enzymes, and assembly factors. One such assembly factor involved in bacterial 30S subunit maturation is ribosomal binding factor A (RbfA). In this study, we present the crystal (determined at 2.2 Å resolution) and NMR structures of RbfA as well as the 2.9 Å resolution cryo-EM reconstruction of the 30S-RbfA complex from Staphylococcus aureus (S. aureus). Additionally, we show that the manner of RbfA action on the small ribosomal subunit during its maturation is shared between bacteria and mitochondria. The obtained results clarify the function of RbfA in the 30S maturation process and its role in ribosome functioning in general. Furthermore, given that S. aureus is a serious human pathogen, this study provides an additional prospect to develop antimicrobials targeting bacterial pathogens.

Proteogenomic analysis of acute myeloid leukemia associates relapsed disease with reprogrammed energy metabolism both in adults and children

Despite improvement of current treatment strategies and novel targeted drugs, relapse and treatment resistance largely determine the outcome for acute myeloid leukemia (AML) patients. To identify the underlying molecular characteristics, numerous studies have been aimed to decipher the genomic- and transcriptomic landscape of AML. Nevertheless, further molecular changes allowing malignant cells to escape treatment remain to be elucidated. Mass spectrometry is a powerful tool enabling detailed insights into proteomic changes that could explain AML relapse and resistance. Here, we investigated AML samples from 47 adult and 22 pediatric patients at serial time-points during disease progression using mass spectrometry-based in-depth proteomics. We show that the proteomic profile at relapse is enriched for mitochondrial ribosomal proteins and subunits of the respiratory chain complex, indicative of reprogrammed energy metabolism from diagnosis to relapse. Further, higher levels of granzymes and lower levels of the anti-inflammatory protein CR1/CD35 suggest an inflammatory signature promoting disease progression. Finally, through a proteogenomic approach, we detected novel peptides, which present a promising repertoire in the search for biomarkers and tumor-specific druggable targets. Altogether, this study highlights the importance of proteomic studies in holistic approaches to improve treatment and survival of AML patients.

TMIC-76. HUMANIN RELEASE FROM TUMOR ASSOCIATED MYELOID CELLS PROMOTES GLIOMA CHEMORESISTANCE

Abstract Transcriptomic screens of brain tumor (glioblastoma; GBM) parenchymal cells indicated tumor supporting traits of the GBM microenvironment, but largely excluded mitochondrially enriched gene-sets. Here, we show that a mitochondrial transcript of GBM parenchymal cells contributes to therapy resistance. We inspected the non-coding transcriptome of human GBM associated myeloid cells (GAM) and observed an upregulation of the mitochondrial ribosomal subunit MT-RNR2, which contains an open reading frame for the signaling peptide humanin. Immunohistology disclosed that humanin was preponderant in GAM. In vitro assays with a range of human stem-like GBM cells (GSCs) revealed that nanomolar concentrations of humanin can drive tumor cell expansion and chemoresistance to temozolomide. A series of genetic, pharmacological and Western blotting experiments showed that extracellular humanin increased GSC viability via stimulation of the GP130/IL6ST receptor and MAPK (Erk) activation. Humanin responsiveness was subject to inter-individual heterogeneity and predominated in GSC with high expression levels of the IL6ST subunit. Mechanistically, humanin promoted the ATR-dependent DNA-repair machinery in GSCs via induction of the DNA-clamp component HUS1. A slice culture model containing human microglia and GSCs confirmed these observations. Humanin is absent from the mouse brain. Exogenous delivery of humanin into orthotopic GBM mouse models or over-expression specifically of a secreted humanin variant recapitulated the in vitro findings. Blockade of the trimeric interleukin receptor with the brain permeant, FDA-approved drug bazedoxifene blocked humanin-mediated chemoresistance in vitro and in vivo. Overall, we identified a clinically applicable compound together with a predictive marker to prevent chemoresistance in a human-specific GBM model.

Schizosaccharomyces pombe Sls1 is primarily required for cox1 mRNA translation.

Mitochondrial DNA (mtDNA) encodes essential subunits of the oxidative phosphorylation (OXPHOS) complexes;thus, the expression of mtDNA-encoded genes is essential for the synthesis of adenosine triphosphate. However, factors involved in mitochondrial translation have not been fully characterized. In this study, we characterized Schizosaccharomyces pombe Sls1, which has sequence similarity to Saccharomyces cerevisiae Sls1 that is required for the translation of all mtDNA-encodedmessenger RNAs (mRNAs). Deletion of S. pombe sls1 severely impaired the growth of the cells on a rich medium containing the nonfermentable carbon source glycerol, which requires mitochondrial respiration. We found that the translation of mtDNA-encoded Cox1, the largest subunit of the cytochrome c oxidase complex, was severely impaired in Δsls1 cells. Deletion of S. pombe sls1 also resulted in a barely detectable steady-state level of mature cox1 mRNA. RNA immunoprecipitation showed that S. pombe Sls1 interacts with cox1 mRNA. Sucrose gradient sedimentation analysis revealed that S. pombe Sls1 is associated with the small subunit of mitochondrial ribosomes. Our results suggest that unlike S. cerevisiae Sls1, S. pombe Sls1 is primarily required for the accumulation and translation of cox1 mRNA.

Mitochondrial ribosomal small subunit (MRPS) MRPS23 protein-protein interaction reveals phosphorylation by CDK11-p58 affecting cell proliferation and knockdown of MRPS23 sensitizes breast cancer cells to CDK1 inhibitors.

Post-translational modification of some mitoribosomal proteins has been found to regulate their functions. MRPS23 has been reported to be overexpressed in various cancers and has been predicted to be involved in increased cell proliferation. Furthermore, MRPS23 is a driver of luminal subtype breast cancer. However, its exact role and function in cancer remains unknown. METHODS ANDRESULTS: Our previous study identified protein-protein interactions involving MRPS23 and CDK11A. In this study, we confirmed the interaction of MRPS23 with the p110 and p58 isoforms of CDK11A. Phosphoprotein enrichment studies and in vitro kinase assay using CDK11A/cyclin D3 followed by MALDI-ToF/ToF analysis confirmed the phosphorylation of MRPS23 at N-terminal serine 11 residue. Breast cancer cells expressing the MRPS23 (S11G) mutant showed increased cell proliferation, increased expression of PI3-AKT pathway proteins [p-AKT (Ser47), p-AKT (Thr308), p-PDK (Ser241) and p-GSK-3β (Ser9)] and increased antiapoptotic pathway protein expression [Bcl-2, Bcl-xL, p-Bcl2 (Ser70) and MCL-1] when compared with the MRPS23 (S11A) mutant-overexpressing cells. This finding indicated the role of MRPS23 phosphorylation in the proliferation and survival of breast cancer cells. The correlation of inconsistent MRPS23 phosphoserine 11 protein expression with CDK11A in the breast cancer cells suggested phosphorylation by other kinases. In vitro kinase assay showed that CDK1 kinase also phosphorylated MRPS23 and that inhibition using CDK1 inhibitors lowered phospho-MRPS23 (Ser11) levels. Additionally, modulating the expression of MRPS23 altered the sensitivity of the cells to CDK1 inhibitors. In conclusion, phosphorylation of MRPS23 by mitotic kinases might potentially be involved in the proliferation of breast cancer cells. Furthermore, MRPS23 can be targeted for sensitizing the breast cancer cells to CDK1 inhibitors.

Bioenergetic and Metabolic Adaptation in Tumor Progression and Metastasis.

The ability of cancer cells to adjust their metabolism in response to environmental changes is a well-recognized hallmark of cancer. Diverse cancer and non-cancer cells within tumors compete for metabolic resources. Metabolic demands change frequently during tumor initiation, progression and metastasis, challenging our quest to better understand tumor biology and develop novel therapeutics. Vascularization, physical constraints, immune responses and genetic instability promote tumor evolution resulting in immune evasion, opportunities to breach basement membrane barriers and spread through the circulation and lymphatics. In addition, the unfolded protein response linked to the ubiquitin proteasome system is a key player in addressing stoichiometric imbalances between nuclear and mitochondrially-encoded protein subunits of respiratory complexes, and nuclear-encoded mitochondrial ribosomal protein subunits. While progressive genetic changes, some of which affect metabolic adaptability, contribute to tumorigenesis and metastasis through clonal expansion, epigenetic changes are also important and more dynamic in nature. Understanding the role of stromal and immune cells in the tumor microenvironment in remodeling cancer cell energy metabolism has become an increasingly important area of research. In this perspective, we discuss the adaptations made by cancer cells to balance mitochondrial and glycolytic energy metabolism. We discuss how hypoxia and nutrient limitations affect reductive and oxidative stress through changes in mitochondrial electron transport activity. We propose that integrated responses to cellular stress in cancer cells are central to metabolic flexibility in general and bioenergetic adaptability in particular and are paramount in tumor progression and metastasis.

A Mysterious World Revealed: Larval-Adult Matching of Deep-Sea Shrimps from the Gulf of Mexico

The identification of deep-sea (&gt;200 m) pelagic larvae is extremely challenging due to the morphological diversity across ontogeny and duration of larval phases. Within Decapoda, developmental stages often differ conspicuously from their adult form, representing a bizarre and mysterious world still left to be discovered. The difficulties with sampling and rearing deep-sea larvae, combined with the lack of taxonomic expertise, argues for the use of molecular methods to aid in identification. Here, we use DNA barcoding combined with morphological methods, to match larval stages with their adult counterpart from the northern Gulf of Mexico and adjacent waters. For DNA barcoding, we targeted the mitochondrial ribosomal large subunit 16S (16S) and the protein coding cytochrome oxidase subunit 1 (COI). These data were combined with previous sequences to generate phylogenetic trees that were used to identify 12 unknown larval and two juvenile species from the infraorder Caridea and the suborder Dendrobranchiata. Once identified, we provide taxonomic descriptions and illustrations alongside the current state of knowledge for all families. For many groups, larval descriptions are missing or non-existent, so this study represents a first step of many to advance deep-sea larval diversity.

Real-Time PCR Assays for Rapid Identification of Common Aphanomyces astaci Genotypes

The oomyceteAphanomyces astaciis the etiologic agent of crayfish plague, a disease that has seriously impacted the populations of European native crayfish species. The introduction of non-indigenous crayfish of North American origin and their wide distribution across Europe have largely contributed to spread of crayfish plague in areas populated by indigenous crayfish. TrackingA. astacigenotypes may thus be a useful tool for investigating the natural history of crayfish plague in its European range, as well as the sources and introduction pathways of the pathogen. In this study, we describe the development of real-time PCR TaqMan assays aiming to distinguish the five genotype groups ofA. astaci(A–E) previously defined by their distinct RAPD patterns. The method was evaluated using DNA extracts from pureA. astacicultures representing the known genotype groups, and fromA. astaci-positive crayfish clinical samples collected mostly during crayfish plague outbreaks that recently occurred in Central Italy and Czechia. The assays do not cross-react with each other, and those targeting genotype groups A, B, D, and E seem sufficiently specific to genotype the pathogen from infected crayfish in the areas invaded byA. astaci(particularly Europe). The unusualA. astacigenotype “SSR-Up” documented from crayfish plague outbreaks in Czechia and chronically infectedPontastacus leptodactylusin the Danube is detected by the group B real-time PCR. The assay originally developed to detect group C (one not yet documented from crayfish plague outbreaks) showed cross-reactivity withAphanomyces fennicus; theA. astacigenotype “rust1” described in the United States fromFaxonius rusticusis detected by that assay as well. Analyses of additional markers (such as sequencing of the nuclear internal transcribed spacer or mitochondrial ribosomal subunits) may complement such cases when the real-time PCR-based genotyping is not conclusive. Despite some limitations, the method is a robust tool for fast genotyping ofA. astacigenotype groups common in Europe, both during crayfish plague outbreaks and in latent infections.