Cells

Human CD34+ progenitors can be differentiated in vitro into proplatelet-producing megakaryocytes (MKs) within 17 days. During this time, four cell populations emerge, phenotypically defined as CD34+CD41+ on day 7 (D7) and CD34+CD41+CD9- on D10 and D14 - qualified as "productive" because they can differentiate into proplatelet-forming cells during the D14-D17 period - and CD34-CD41+ or CD34+CD41+CD9+ on day 10 - qualified as "unproductive" because they are unable to form proplatelets later. Coculture with mesenchymal stem cells, or the presence of the AHR antagonist SR1, boosts the productive pathway in two ways: firstly, it increases the yield of D10 and D14 CD34+CD41+CD9- cells and secondly, it greatly increases their ability to generate proplatelets; in contrast, SR1 has no noticeable effect on the unproductive cell types. A transcriptome analysis was performed to decipher the genetic basis of these properties. This work represents the first extensive description of the genetic perturbations which accompany the differentiation of CD34+ progenitors into mature MKs at a subpopulation level. It highlights a wide variety of biological changes modulated in a time-dependent manner and allows anyone, according to his/her interests, to focus on specific biological processes accompanying MK differentiation. For example, the modulation of the expression of genes associated with cell proliferation, lipid and cholesterol synthesis, extracellular matrix components, intercellular interacting receptors and MK and platelet functions reflected the chronological development of the productive cells and pointed to unsuspected pathways. Surprisingly, SR1 only affected the gene expression profile of D10 CD34+CD41+CD9- cells; thus, as compared to these cells and those present on D14, the poorly productive D10 CD34+CD41+CD9- cells obtained in the absence of SR1 and the two unproductive populations present on D10 displayed an intermediate gene expression pattern. In other words, the ability to generate proplatelets between D10 and D14 appeared to be linked to the capacity of SR1 to delay MK differentiation, meanwhile avoiding intermediate and inappropriate genetic perturbations. Paradoxically, the D14 CD34+CD41+CD9- cells obtained under SR1- or SR1+ conditions were virtually identical, raising the question as to whether their strong differences in terms of proplatelet production, in the absence of SR1 and between D14 and D17, are mediated by miRNAs or by memory post-translational regulatory mechanisms.

HighlightsO_LIIdentified circRNAs expressed in {beta}TC6 cell line C_LIO_LIFirst report identifying glucose-regulated circRNAs in pancreatic {beta}-cell C_LIO_LICircRabep1 regulates {beta}-cell growth by binding to miR-335-3p C_LI Circular RNAs (circRNAs) are a large family of closed-loop RNA molecules emerging as novel regulators of gene expression. Although several circRNAs are known to regulate various biological processes, the functions of most circRNAs expressed in pancreatic {beta}-cells remain to be discovered. Since short-term glucose treatment induces pancreatic {beta}-cell growth and promotes insulin production, we wanted to explore the role of glucose-regulated circRNAs in pancreatic {beta}-cell physiology. Our RNA-seq analysis identified more than 300 differentially expressed circRNAs in high-glucose compared to low-glucose treated {beta}TC6 cells. A subset of differentially expressed and abundant circRNAs was validated by various biochemical methods, including circular RNA Rabep1 (circRabep1). Moreover, the downregulation of circRabep1 in high glucose-treated {beta}TC6 cells suggested a possible function in {beta}-cell physiology. Furthermore, analysis of the circRabep1-miRNA-mRNA regulatory network discovered the association of circRabep1 with miR-335-3p, a suppressor of Pten expression. Importantly, inhibition of miRNA function by miR-335-3p inhibitor results in upregulation of PTEN levels, suppressing {beta}-cell growth and proliferation. Furthermore, silencing circRabep1 decreased PTEN expression by sponging miR-335-3p, promoting cell proliferation. We propose that the downregulation of circRabep1 in high-glucose treated {beta}-cell leads to an increase in {beta}-cell proliferation by suppressing PTEN expression through derepression of miR-335-3p. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=62 SRC="FIGDIR/small/600308v1_ufig1.gif" ALT="Figure 1"> View larger version (10K): org.highwire.dtl.DTLVardef@542b03org.highwire.dtl.DTLVardef@1d3f3faorg.highwire.dtl.DTLVardef@36b476org.highwire.dtl.DTLVardef@181c7b4_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical AbstractC_FLOATNO Schematic showing the molecular function of glucose-regulated circRabep1 in pancreatic -cell growth by binding to miR-335-3p. C_FIG

Mitochondrial dynamics is important for cellular health and includes morphology, fusion, fission, vesicle formation, transport and contact formation with other organelles. Myosin XIX (Myo19) is an actin-based motor which competes with TRAK1/2 adaptors of microtubule-based motors for binding to the outer mitochondrial membrane receptors Mitochondrial Rho GTPases 1/2 (Miro). Currently, it is poorly understood how Myo19 contributes to mitochondrial dynamics. Here, we report on a Myo19-deficient mouse model and the ultrastructure of the mitochondria from cells of Myo19-deficient mice and HEK cells, Miro-deficient HEK cells and TRAK1-deficient HAP1 cells. Myo19-deficient mitochondria in kidney, skeletal and cardiac muscle cells, MEFs and HEK cells have morphological alterations in the inner mitochondrial membrane with reduced numbers of malformed cristae. In addition, mitochondria in Myo19-deficient cells showed fewer ER-mitochondria contact sites (ERMCS). In accordance with the ultrastructural observations, Myo19-deficient MEFs had lower oxygen consumption rates and a reduced abundance of OXPHOS supercomplexes. The simultaneous loss of Miro1 and Miro 2 led to a comparable mitochondria phenotype and reduced ERMCS as observed upon loss of Myo19. However, the loss of TRAK1 caused only a reduction in the number of cristae, but not ERMCS. These results demonstrate that both actin- and microtubule-based motors regulate cristae formation, but only Myo19 and its membrane receptor Miro regulate ERMCS.

We previously identified a unique genetic feature of Autism Spectrum Disorder (ASD) in human patients and established mouse models, namely the low to very low level of six microRNAs, miR-19a-3p, miR-361-5p, miR-3613-3p, miR-150-5p, miR-126-3p and miR-499a-5p. We attempted to interfere experimentally with the expression in the mouse of two of them, miR19a-3p and miR499a-5p by microinjecting into the one-cell embryo either the complementary sequence or an excess of the microRNA. Both approaches resulted in low levels in the somatic tissues and sperm of the targeted microRNAs (nascent) and their pri and pre precursors. The altered miRNA profiles were inherited by progenies of crosses with untreated partners together with behavior alterations partly characteristic of ASD patients and animal models. An excess of miRNA in the eggs leads to a specific downregulation, we propose variations of single-stranded miRNA, as effectors of its own transcription in eukaryotes.

Oxidative distress and inflammation are common biochemical disorders in individuals with cancer. The measurement of oxidative stress in oncology can be useful in clinical practice to monitor the effectiveness of therapy and unwanted effects of the treatment. Thus, the aim of the present study was to evaluate the redox status through the reactive oxygen metabolites (d-ROMs) and biological antioxidant potential (BAP) tests and investigate the correlations of these parameters with blood variables in cancer patients. This is an observational, retrospective study of analysis of medical records of patients evaluated the period from 2018 to 2020 in an integrative medicine center. The inclusion criteria were individuals of both sexes, over 18 years of age, diagnosed with cancer who performed the d-ROMs and BAP test in the same period of blood analysis. Following the inclusion criteria, the final sample of the study were 57 individuals, 60% were woman and 40% were men. The evaluation of redox state showed that the d-ROMs were high (420.2 {+/-} 112.1 U CARR) in total sample and higher in women compared to male (p < 0.01) and BAP tests were normal (2332 {+/-} 812 mol/l). The oxidative parameters, d-ROMs and OSI, was correlated positively with BAP, red cell distribution width (only d-ROMs), platelets (Plt), C-reactive protein (CRP), erythrocyte sedimentation (ESR) and negatively with hemoglobin (Hb) and mean corpuscular hemoglobin (MCH). Regarding the antioxidant potential index, BAP/dROMs, were correlated positively with Hb and serum albumin (HAS) and negatively correlated with Plt, CRP and ESR. The study shows that redox status of an individual with cancer is altered, and it is possible to monitor this system in clinical practice through d-ROMs and BAP test. These parameters, in addition to being suitable for assessing oxidative stress, were correlated with parameters predictors of inflammation.

We previously reported the presence of the intermediate filament vimentin at the primary cilium of lung cancer epithelial cells. In this study we further demonstrate that vimentin is intimately intertwined with acetylated tubulin at this structure. Interestingly, although vimentin can be detected along the whole length of the primary cilium, phospho-serine 56 vimentin is found particularly enriched at its basal region in A549 lung cancer cells. Vimentin appears to play a pivotal role in ciliogenesis, since its depletion in MEF or in A549 cells results in a lower proportion of cells displaying primary cilia and recognizable basal bodies. Furthermore, the detectable cilia in vimentin depleted cells are shorter. In addition, the centriolar structure appears disrupted in vimentin deficient cells, as indicated by an abnormal distribution of {gamma}- and acetylated tubulin. Moreover, these cells display a defective organization of the pericentriolar material, characterized by a marked decrease in the levels of pericentrin and a diffuse distribution of Rab11. Taken together, our results show that vimentin is present at the primary cilium and suggest that it plays an important role in cilium structure and biogenesis, since its depletion leads to marked morphological defects and altered organization of key elements of this structure.

Envelope-Limited Chromatin Sheets (ELCS) can be induced in human promyelocytic HL-60/S4 cells by treatment with retinoic acid (RA). After 4 days, the differentiated granulocytes exhibit multilobed nuclei with outgrowths of the nuclear envelope (NE) and associated heterochromatin extending into the surrounding cytoplasm (ELCS). These fascinating structures reveal a periodic meshwork of 30 nm chromatin fibers, when viewed by Cryo-electron microscopy. Genetic and biochemical evidence indicates that RA increases the synthesis of Lamin B Receptor (LBR), which is a key enzyme for Cholesterol biosynthesis and is an essential bridge between the NE and peripheral heterochromatin. This article is in part a review of our microscopic data on the structure of ELCS, and in part a description of related transcription changes that result in the formation of ELCS. In addition, this article contains a structural and biochemical comparison of RA-induced granulocytes with phorbol ester (TPA) induced HL-60/S4 macrophages, which lack nuclear lobulation, do not form ELCS, and exhibit a reduction in LBR and Cholesterol biosynthesis. From our perspective, ELCS can be viewed as "fabric" outgrowths of the nuclear envelope, frequently connecting nuclear lobes and capable of sustaining the twisting and squeezing distortions imposed upon nuclear shape, as the granulocytes traverse narrow tissue channels.

Oligo-astheno-teratozoospermia (OAT), a recurent cause of male infertility, is the most frequent disorder of spermatogenesis with a probable genetic cause. Patients and mice bearing mutations in the ARMC2 gene have a decreased sperm concentration, and individual sperm show multiple morphological defects and a lack of motility - a canonical OAT phenotype. Intracytoplasmic sperm injection (ICSI) is required to treat such a condition but it is associated with a small increase in birth defects in comparison to pregnancies not involving assisted conception. Consequently, new targeted treatments are needed to restore fertility. Here, a combination of in vivo injection and electroporation of capped and poly-A-tailed naked mRNA is tested as a strategy to treat ARMC2-related infertility in mouse. mRNAs coding for several reporter genes are tested and the efficiency and the kinetic of expression are assessed using in vivo and in vitro 2D and 3D imaging experiments. We show that mRNA-coded reporter proteins are detected for up to 3 weeks in germ cells, making the use of mRNA possible to treat infertility. We compare these results with those obtained with a non-integrative plasmid Enhanced Episomal Vector (EEV), which induces low and transient expression in spermatogenic cells. Consequently, injection and electroporation of naked mRNA-Armc2 into the testes of Armc2-deficient males were performed and we show the presence of normal and motile sperm in the epididymis. These motile sperm were able to produce embryos by IVF and ICSI. This study demonstrates, for the first time, that mRNA electroporation can restore sperm motility and partially fertilizing ability, providing a proof-of-concept for mRNA-based strategies to correct monogenic causes of male infertility and opening new avenues for male infertility treatment.

Differential expression of genes involved in physiological processes are a collaborative outcome of interactions among signalling molecules, downstream effectors and epigenetic modifiers, which together dictate the regulation of genes in response to specific stimuli. MLLs and KDM5A are functionally antagonistic proteins as one acts as writer and the other as eraser of the active chromatin mark, i.e., H3K4me3. KDM5A promotes EMT by occupying promoters of both epithelial and mesenchymal markers. Through this work, it is illustrated that when bound to E-cadherin promoter, KDM5A acts as a classical repressor by demethylating H3K4me3, but on mesenchymal marker promoters, it acts as a transcriptional activator by inhibiting the activity of HDACs and increasing H3K18ac. Further it is demonstrated that KDM5A occupancy enhances either MLL1 or MLL2 by physically interacting with them and that signalling pathways regulate the enzymatic activity of KDM5A probably by phosphorylation. When not active, KDM5A signals for MLL occupancy, a mechanism that can be called epigenetic signalling.

Epithelial-mesenchymal transition (EMT) is a key cellular transformation for many physiological and pathological processes ranging from cancer over wound healing to embryogenesis. Changes in cell migration, cell morphology and cellular contractility were identified as hallmarks of EMT. These cellular properties are known to be tightly regulated by the actin cytoskeleton. EMT-induced changes of actin-cytoskeletal regulation were demonstrated by previous reports of cell-cycle-dependent changes of actin cortex mechanics in conjunction with characteristic modifications of cortex-associated f-actin and myosin. However, at the current state, the changes of upstream actomyosin signalling that lead to corresponding mechanical and compositional changes of the cortex are not well understood. In this work, we show in breast epithelial cancer cells MCF-7 that EMT results in characteristic changes of the cortical signalling of Rho-GTPases Rac1, RhoA and RhoC and downstream actin regulators cofilin, mDia1 and Arp2/3. In the light of our findings, we propose that cell-cycle-dependent EMT-induced changes in cortical mechanics rely on two hitherto unappreciated signalling paths - i) a cell-cycle-dependent interaction between Rac1 and RhoC and ii) an inhibitory effect of Arp2/3 activity on cortical association of myosin II.

HIV-related comorbidities appear to be related to chronic inflammation, a condition characterizing people living with HIV (PLWH). Prior work indicates that cannabidiol (CBD) might reduce inflammation; however, the genetics underpinning of this effect are not well investigated. Our main objective is to detect gene expression alterations in human peripheral blood mononuclear cells (PBMCs) from PLWH after at least one month of CBD treatment. We analyze [~]41,000 PBMCs from three PLWH at baseline and after CBD treatment (27-60 days). We obtained a coherent signature, characterized by an anti-inflammatory activity, of differentially expressed genes in myeloid cells. Our study shows how CBD is associated with alterations of gene expression in myeloid cells after CBD treatment.

The increasing prevalence of Alzheimers disease demands research into therapeutic strategies that go beyond Amyloid and Tau. Synaptic loss, neuritic loss, and microtubule destabilization due to misfolded Tau and dysfunctional signalling in the AD-affected neuron, all point toward understanding and targeting cytoskeletal dysregulation in AD. Here we present, an extensive study on the novel role of the ZnF UBP (Zinc Finger Ubiquitin Binding Protein) domain of HDAC6 (Histone Deacetylase 6) in actin remodelling in neurons. We have demonstrated this function through immunofluorescence colocalization analysis in actin-rich podosome structures. We have found that this HDAC6 domain induces increased localization of the actin polymerization proteins, Arp2 and WASP and the adaptor protein TKS5 in the podosome structures. We have also extended our work to understand the potential of this domain in enhancing the podosome-mediated migration of neuronal cells. It was thus established that HDAC6 ZnF UBP induces increased association of cytoskeletal proteins within the podosomes, conferring enhanced migration potential to neurons and presenting an interesting strategy to improve neuronal health.

Mutations in the MYH9 gene, which encodes the actin-based molecular motor non-muscle myosin II-A (NM2-A), cause a group of blood disorders termed MYH9-related diseases (MYH9-RD). While correlation between genotype and phenotype is not well characterized at a molecular level, motor mutations seem to cause more severe phenotypes than tail mutations. Motor domain mutation N93K, previously described as activity-impairing, causes in fact an almost non-significant defect on motor function in vitro. Conversely, it increases NM2-A filament stability and interaction with the myosin chaperone UNC45a in stress fiber-forming cells. This also alters its subcellular localization and effect on adhesion dynamics. Similar cellular effects are observed in cells expressing NM2-A E1841K, a prototypical tail mutation. In cells devoid of stress fibers such as megakaryocytes, NM2-A N93K forms large, amorphous, concentration-dependent aggregates that also contain wild type NM2-A and UNC45a. Conversely, NM2-A E1841K forms concentration-independent aggregates that exclude wild type NM2-A and UNC45a. Our data shows that the N93K mutation reduces the fraction of functional cellular NM2-A by enhancing the stability of NM2-A filaments and/or promoting protein aggregation together with wild type NM2-A. Conversely, NM2-A E1841K form aggregates that do not affect wild type NM2-A. These observations are consistent with the molecular severity observed in primary cells from patients of these genotypes.

In an effort to extend our understanding of the genetic functions of the nuclear envelope protein Lamin B Receptor (LBR), we examined the effect of a stable short hairpin (sh1) RNAi knockdown of LBR on the transcriptome and immunostained morphology of the human myeloid leukemia cell line (HL-60/S4). This examination was on sh1 cells induced to granulocytic form with Retinoic Acid (RA) versus sh1 cells maintained undifferentiated (0). By comparison to control cells (i.e., not sh1), we obtained gene lists that were differentially expressed only in the LBR knockdown cell line (i.e., "only-sh1-down" and "only-sh1-up"), in RA versus 0 cells. These curated gene lists were examined by Gene Ontology (GO) analysis. Aside from chromatin related GO terms, the most surprising finding was a significant downregulation of Golgi related genes only in the sh1 cells. Possible relationships between the "Cis-Golgi-Network" and LBR are discussed. Another surprise was a significant upregulation of "Ribosome" protein transcripts only in the sh1 cells. In parallel to these findings, an immunostaining comparison of nucleoli in S4 and sh1 cells demonstrated that the number and location of nucleoli in a single nucleus differs, depending upon the presence of LBR. Speculations on the influence of LBR levels upon the liquid-liquid phase separation model of nucleolar condensation are presented.

The timing of the M-phase entry and its progression are precisely controlled by a CDC6-dependent mechanism that inhibits the major mitotic kinase CDK1, and, thus, regulates the dynamic of CDK1 during the M-phase. In this paper, we describe the differential regulation of the mitotic CDK1 dynamics by exogenous cyclin A or a non-degradable cyclin B added to the Xenopus laevis embryo cycling extracts. We showed that the variations in the level of cyclin B modify both CDK1 activity and the timing of the M-phase progression, while the cyclin A levels modify only CDK1 activity without changing the timing of the M-phase events. In consequence, CDC6 regulates the M-phase through endogenous cyclin B, but not cyclin A, which we demonstrated directly by the depletion of cyclin A, and the addition of CDC6 to the cycling extracts. Further, we showed, by p9 precipitation (p9 protein associates with Cyclin-Dependent Kinases, CDK), followed by the Western blotting that CDC6, and the bona fide CDK1 inhibitor Xic1, associate with CDK1 and/or another CDK present in Xenopus embryos, the CDK2. Finally, we demonstrated that the Xic1 temoprarily separates from the mitotic CDK complexes during the peak of CDK1 activity. These data show the differential coordination of the M-phase progression by CDK1/cyclin A and CDK1/cyclin B, confirm the critical role of the CDC6-dependent CDK1 inhibition in this process and show that CDC6 acts through the cyclin B- and not cyclin A/CDK complexes. This CDC6- and cyclin B-dependent mechanism may also depend on the precisely regulated association of Xic1 with the CDK complexes. We postulate that the dissociation of Xic1 from the CDK complexes allows the maximal activation of CDK1 during the M-phase.

The authors have withdrawn their manuscript whilst they perform additional experiments to test some of their conclusions further. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author

Muscle RING-finger protein 1 (MuRF1, gene name: TRIM63) is well known as a critical molecular regulator in skeletal muscle atrophy. Despite the identification of several substrates and interaction partners for MuRF1, the precise molecular mechanisms by which MuRF1 causes skeletal muscle atrophy remain unclear. To gain further insight into the underlying mechanism of skeletal muscle atrophy, we applied targeted biochemical approaches, and identified tripartite motif-containing protein 72 (TRIM72) as a novel MuRF1-interacting protein. Subsequent analysis using MuRF1 knockout and rescue experiments showed that TRIM72 protein abundance is dependent on the presence of MuRF1 protein. Furthermore, TRIM72 protein level was increased by dexamethasone treatment in C2C12 myotubes, alongside increased MuRF1 protein level. Dexamethasone decreases IRS1/Akt signalling, protein synthesis, and glucose uptake specifically in wild-type myotubes, but not in MuRF1 KO myotubes. Further analysis showed that overexpression of TRIM72 impairs IRS1/Akt signalling without the presence of MuRF1, indicating that MuRF1 induces a negative impact on insulin signalling through a plausible cooperation with TRIM72. Our findings provide novel non-degradative molecular roles of MuRF1 that link together skeletal muscle atrophy and impaired insulin responses. HighlightsO_LIIdentification of MuRF1 and TRIM72 interaction in skeletal muscle cells C_LIO_LITRIM72 protein expression is dependent on the presence of MuRF1 protein C_LIO_LIDeletion of MuRF1 confers a protective effect against dexamethasone-induced impairment of IRS1/Akt signaling C_LIO_LITRIM72 is sufficient to impair IRS1/Akt signaling C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=149 HEIGHT=200 SRC="FIGDIR/small/658491v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@347734org.highwire.dtl.DTLVardef@7dfa1aorg.highwire.dtl.DTLVardef@aef16dorg.highwire.dtl.DTLVardef@16c3bde_HPS_FORMAT_FIGEXP M_FIG C_FIG

Today septins are considered as the fourth component of the cytoskeleton with the Septin-7 isoform playing a critical role in the formation of higher order structures. While its importance has already been confirmed in several intracellular processes of different organs, very little is known about its role in skeletal muscle. Here, using Septin-7 conditional knock-down mouse model, the C2C12 cell line, and enzymatically isolated adult muscle fibers the organization and localization of septin filaments is revealed, and an ontogenesis-dependent expression of Septin-7 is demonstrated. KD mice displayed a characteristic hunchback phenotype with skeletal deformities, reduction in vivo and in vitro force generation, and disorganized mitochondrial networks. Furthermore, knock-out of Septin-7 in C2C12 cells resulted in complete loss of cell division while KD cells provided evidence that Septin-7 is essential in proper myotube differentiation. These and the transient increase in Septin-7 expression following muscle injury demonstrate its vital contribution to muscle regeneration and development.

Ciliopathies are a class of multi-systemic genetic diseases characterized by ciliary dysfunction. Here, we report a novel ANKS3 variant in patients with a renal ciliopathy known as nephronophthisis (NPH) associated with hepatic defects. ANKS3 is an ankyrin and sterile alpha motif domain-containing protein that interacts with many NPH proteins as well as with BICC1, an RNA-binding protein involved in renal cystic diseases. The pathogenic effect of the ANKS3 mutation was validated in the zebrafish mutant and knock-in rat model, the latter showing urine concentration defect and tubular dilatations similar to NPH patients. In addition, cilia morphology and function as well as epithelialization of kidney tubular cells was affected by loss or mutation of ANKS3. Finally, our results evidenced that these classically renal ciliopathy-associated phenotypes were linked to the negative regulation of BICC1 by ANKS3 which binds to transcripts of the major NPH gene NPHP1 and mediates their decay through the AGO2-RISC complex and recruitment into P-bodies. Altogether, our findings suggest that the ANKS3/BICC1 complex is a key post-transcriptional regulator of NPHP1 transcript stability, providing another level of regulation of cilium biogenesis and kidney homeostasis, as well as an unusual mechanism leading to NPH-related ciliopathies.

Friedreich ataxia (FRDA) is a neurodegenerative disorder characterized by neuromuscular and neurological manifestations. It is caused by mutations in gene FXN, which results in loss of the mitochondrial protein frataxin. Endoplasmic Reticulum-mitochondria associated membranes (MAMs) are inter-organelle structures involved in the regulation of essential cellular processes, including lipid metabolism and calcium signaling. In the present study, we have analyzed in both, unicellular and multicellular models of FRDA, an analysis of calcium management and of integrity of MAMs. We observed that function of MAMs is compromised in our cellular model of FRDA, which was improved upon treatment with antioxidants. In agreement, promoting mitochondrial calcium uptake was sufficient to restore several defects caused by frataxin deficiency in Drosophila Melanogaster. Remarkably, our findings describe for the first time frataxin as a member of the protein network of MAMs, where interacts with two of the main proteins implicated in endoplasmic reticulum-mitochondria communication. These results suggest a new role of frataxin, indicate that FRDA goes beyond mitochondrial defects and highlight MAMs as novel therapeutic candidates to improve patients conditions.