Novel Variant of FDXR as a Molecular Etiology of Postlingual Post-Synaptic Auditory Neuropathy Spectrum Disorder via Mitochondrial Dysfunction: Reiteration of the Correlation between Genotype and Cochlear Implantation Outcomes.

Objectives: FDXR encodes the mitochondrial ferredoxin reductase, which is associated with auditory neuropathy spectrum disorder (ANSD) and optic atrophy. Only two studies have described FDXRrelated hearing loss. The auditory rehabilitation outcomes of this disease entity have not been investigated, and the pathophysiologic mechanism is not well elucidated. Here we report a hearingimpaired subject with co-segregation of the FDXR variant and post-synaptic type ANSD, who underwent cochlear implantation (CI) with favorable outcomes. We suggest a possible pathophysiologic mechanism of adult-onset ANSD via mitochondrial dysfunction. Methods: A 35-year-old woman was ascertained to have ANSD. Exome sequencing identified the genetic cause of hearing loss, and functional study measuring mitochondrial activity was performed to provide molecular evidence of pathophysiology. Expression of FDXR in the mouse cochlea was evaluated by immunohistochemistry. Intraoperatively, electrically-evoked compound action potential (ECAP) responses were measured, and mapping parameters were adjusted accordingly. Audiological outcomes were monitored for over 1 year. Results: In lymphoblastoid cell lines (LCLs) carrying a novel FDXR variant, decreased ATP and MtMP levels and increased ROS levels were observed compared to control LCLs. These dysfunctions were restored by administering mitochondria isolated from umbilical cord mesenchymal stem cells, confirming the pathogenic potential of this variant via mitochondrial dysfunction. Partial ECAP responses during CI and FDXR expression in the mouse cochlea indicate that FDXR-related ANSD is postsynaptic. By increasing the pulse width during mapping, the patient's CI outcomes showed significant improvement over 1-year post-CI. Conclusion: Post-synaptic ANSD due to a novel FDXR variant linked to mitochondrial dysfunction was identified first in a Korean, and 1-year post CI outcomes were reported for the first time in the literature. Excellent audiologic results were obtained, and our results reiterate the correlation between genotype and CI outcomes in ANSD.

Mitochondrial transplantation exhibits neuroprotective effects and improves behavioral deficits in an animal model of Parkinson's disease.

Mitochondria are essential organelles for cell survival that manage the cellular energy supply by producing ATP. Mitochondrial dysfunction is associated with various human diseases, including metabolic syndromes, aging, and neurodegenerative diseases. Among the diseases related to mitochondrial dysfunction, Parkinson's disease (PD) is the second most common neurodegenerative disease and is characterized by dopaminergic neuronal loss and neuroinflammation. Recently, it was reported that mitochondrial transfer between cells occurred naturally and that exogenous mitochondrial transplantation was beneficial for treating mitochondrial dysfunction. The current study aimed to investigate the therapeutic effect of mitochondrial transfer on PD in vitro and in vivo. The results showed that PN-101 mitochondria isolated from human mesenchymal stem cells exhibited a neuroprotective effect against 1-methyl-4-phenylpyridinium, 6-hydroxydopamine and rotenone in dopaminergic cells and ameliorated dopaminergic neuronal loss in the brains of C57BL/6J mice injected 30 â€‹mg/kg of methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intraperitoneally. In addition, PN-101 exhibited anti-inflammatory effects by reducing the expression of pro-inflammatory cytokines in microglial cells and suppressing microglial activation in the striatum. Furthermore, intravenous mitochondrial treatment was associated with behavioral improvements during the pole test and rotarod test in the MPTP-induced PD mice. These dual effects of neuroprotection and anti-neuroinflammation support the potential for mitochondrial transplantation as a novel therapeutic strategy for PD.

An optimized Nurr1 agonist provides disease-modifying effects in Parkinson's disease models.

The nuclear receptor, Nurr1, is critical for both the development and maintenance of midbrain dopamine neurons, representing a promising molecular target for Parkinson's disease (PD). We previously identified three Nurr1 agonists (amodiaquine, chloroquine and glafenine) that share an identical chemical scaffold, 4-amino-7-chloroquinoline (4A7C), suggesting a structure-activity relationship. Herein we report a systematic medicinal chemistry search in which over 570 4A7C-derivatives were generated and characterized. Multiple compounds enhance Nurr1's transcriptional activity, leading to identification of an optimized, brain-penetrant agonist, 4A7C-301, that exhibits robust neuroprotective effects in vitro. In addition, 4A7C-301 protects midbrain dopamine neurons in the MPTP-induced male mouse model of PD and improves both motor and non-motor olfactory deficits without dyskinesia-like behaviors. Furthermore, 4A7C-301 significantly ameliorates neuropathological abnormalities and improves motor and olfactory dysfunctions in AAV2-mediated α-synuclein-overexpressing male mouse models. These disease-modifying properties of 4A7C-301 may warrant clinical evaluation of this or analogous compounds for the treatment of patients with PD.

Human platelet mitochondria improve the mitochondrial and cardiac function of donor heart.

Mitochondria transplantation emerges as an effective therapeutic strategy for ischemic-related diseases but the roles in the donor hearts for transplant remain unidentified. Here, we investigated whether the preservation of the donor heart with human platelet-derived mitochondria (pl-MT) could improve mitochondrial and cardiac function. Incubation with pl-MT resulted in the internalization of pl-MT and the enhancement of ATP production in primary cardiomyocytes. In addition, incubation of rat hearts with pl-MT ex vivo for 9 h clearly demonstrated pl-MT transfusion into the myocardium. Mitochondria isolated from the hearts incubated with pl-MT showed increased mitochondrial membrane potential and greater ATP synthase activity and citrate synthase activity. Importantly, the production of reactive oxygen species from cardiac mitochondria was not different with and without pl-MT incubation. Functionally, the heartbeat and the volume of coronary circulation perfusate were significantly increased in the Langendorff perfusion system and the viability of cardiomyocytes was increased from pl-MT hearts.Taken together, these results suggest that incubation with Pl-MT improves mitochondrial activity and maintains the cardiac function of rat hearts with prolonged preservation time. The study provides the proof of principle for pl-MT application as an enhancer of the donor heart.

Primary astrocytic mitochondrial transplantation ameliorates ischemic stroke.

Mitochondria are important organelles that regulate adenosine triphosphate production, intracellular calcium buffering, cell survival, and apoptosis. They play therapeutic roles in injured cells via transcellular transfer through extracellular vesicles, gap junctions, and tunneling nanotubes. Astrocytes can secrete numerous factors known to promote neuronal survival, synaptic formation, and plasticity. Recent studies have demonstrated that astrocytes can transfer mitochondria to damaged neurons to enhance their viability and recovery. In this study, we observed that treatment with mitochondria isolated from rat primary astrocytes enhanced cell viability and ameliorated hydrogen peroxide-damaged neurons. Interestingly, isolated astrocytic mitochondria increased the number of cells under damaged neuronal conditions, but not under normal conditions, although the mitochondrial transfer efficiency did not differ between the two conditions. This effect was also observed after transplanting astrocytic mitochondria in a rat middle cerebral artery occlusion model. These findings suggest that mitochondria transfer therapy can be used to treat acute ischemic stroke and other diseases. [BMB Reports 2023; 56(2): 90-95].

Platelet-derived mitochondria transfer facilitates wound-closure by modulating ROS levels in dermal fibroblasts.

Platelets are known to improve the wound-repair capacity of mesenchymal stem cells (MSCs) by transferring mitochondria intercellularly. This study aimed to investigate whether direct transfer of mitochondria (pl-MT) isolated from platelets could enhance wound healing in vitro using a cell-based model. Wound repairs were assessed by 2D gap closure experiment in wound scratch assay using human dermal fibroblasts (hDFs). Results demonstrated that pl-MT were successfully internalized into hDFs. It increased cell proliferation and promoted the closure of wound gap. Importantly, pl-MT suppressed both intracellular and mitochondrial ROS production induced by hydrogen peroxide, cisplatin, and TGF-ß in hDFs. Taken together, these results suggest that pl-MT transfer might be used as a potential therapeutic strategy for wound repair.

What is the context? During the wound healing process, abnormal regulation of ROS and inflammation delays the healing process, resulting in chronic non-healing wounds.Mitochondria are key organelles responsible for the ROS generation. Mitochondrial dysfunction has been implicated in delayed wound repair.Mitochondria transfer, which utilizes intact mitochondria isolated from healthy cells to recover from disease, has been applied in various clinical studies, but additional evidence is needed to apply it to wound healing.What is new? In this study, we chose platelets as a cell source for mitochondrial transfer. We isolated the functional mitochondria from platelets and applied them to wound healing.What is the impact? This study provides evidence that platelet-derived mitochondria (pl-MT) improve the wound healing progress by increasing the viability of dermal fibroblasts and suppressing intracellular and mitochondrial ROS production.Platelets have also been demonstrated to be a suitable cell source for mitochondrial transfer.

Preferred Migration of Mitochondria toward Cells and Tissues with Mitochondrial Damage.

Mitochondria are organelles that play a vital role in cellular survival by supplying ATP and metabolic substrates via oxidative phosphorylation and the Krebs cycle. Hence, mitochondrial dysfunction contributes to many human diseases, including metabolic syndromes, neurodegenerative diseases, cancer, and aging. Mitochondrial transfer between cells has been shown to occur naturally, and mitochondrial transplantation is beneficial for treating mitochondrial dysfunction. In this study, the migration of mitochondria was tracked in vitro and in vivo using mitochondria conjugated with green fluorescent protein (MTGFP). When MTGFP were used in a coculture model, they were selectively internalized into lung fibroblasts, and this selectivity depended on the mitochondrial functional states of the receiving fibroblasts. Compared with MTGFP injected intravenously into normal mice, MTGFP injected into bleomycin-induced idiopathic pulmonary fibrosis model mice localized more abundantly in the lung tissue, indicating that mitochondrial homing to injured tissue occurred. This study shows for the first time that exogenous mitochondria are preferentially trafficked to cells and tissues in which mitochondria are damaged, which has implications for the delivery of therapeutic agents to injured or diseased sites.

Erratum to: Human umbilical cord mesenchymal stem cell-derived mitochondria (PN-101) attenuate LPS-induced inflammatory responses by inhibiting NFκB signaling pathway.

[Erratum to: BMB Reports 2022; 55(3): 136-141, PMID: 34488927, PMCID: PMC8972135] The BMB Reports would like to correct in BMB Rep. 55(3):136-141, titled "Human umbilical cord mesenchymal stem cell-derived mitochondria (PN-101) attenuate LPS-induced inflammatory responses by inhibiting NFκB signaling pathway". This research was supported by NRF-2016R1A2B4007640 grant (to C-H Kim). Since grant number is incorrect, this information has now been corrected as follows: We would like to thank various Paean Biotechnology Inc. members who participated in the project. This work was supported by NRF-2018M3A9B5023055 grant (to C-H Kim). The authors apologize for any inconvenience or confusion that may be caused by this error. The ACKNOWLEDGEMENTS of Original PDF version have been corrected.

LIN28A enhances regenerative capacity of human somatic tissue stem cells via metabolic and mitochondrial reprogramming.

Developing methods to improve the regenerative capacity of somatic stem cells (SSCs) is a major challenge in regenerative medicine. Here, we propose the forced expression of LIN28A as a method to modulate cellular metabolism, which in turn enhances self-renewal, differentiation capacities, and engraftment after transplantation of various human SSCs. Mechanistically, in undifferentiated/proliferating SSCs, LIN28A induced metabolic reprogramming from oxidative phosphorylation (OxPhos) to glycolysis by activating PDK1-mediated glycolysis-TCA/OxPhos uncoupling. Mitochondria were also reprogrammed into healthy/fused mitochondria with improved functional capacity. The reprogramming allows SSCs to undergo cell proliferation more extensively with low levels of oxidative and mitochondrial stress. When the PDK1-mediated uncoupling was untethered upon differentiation, LIN28A-SSCs differentiated more efficiently with an increase of OxPhos by utilizing the reprogrammed mitochondria. This study provides mechanistic and practical approaches of utilizing LIN28A and metabolic reprogramming in order to improve SSCs utility in regenerative medicine.

Human umbilical cord mesenchymal stem cell-derived mitochondria (PN-101) attenuate LPS-induced inflammatory responses by inhibiting NFκB signaling pathway.

Inflammation is one of the body's natural responses to injury and illness as part of the healing process. However, persistent inflammation can lead to chronic inflammatory diseases and multi-organ failure. Altered mitochondrial function has been implicated in several acute and chronic inflammatory diseases by inducing an abnormal inflammatory response. Therefore, treating inflammatory diseases by recovering mitochondrial function may be a potential therapeutic approach. Recently, mitochondrial transplantation has been proven to be beneficial in hyperinflammatory animal models. However, it is unclear how mitochondrial transplantation attenuates inflammatory responses induced by external stimuli. Here, we isolated mitochondria from umbilical cord-derived mesenchymal stem cells, referred as to PN-101. We found that PN-101 could significantly reduce LPS-induced mortality in mice. In addition, in phorbol 12-myristate 13-acetate (PMA)-treated THP-1 macrophages, PN-101 attenuated LPS-induced increase production of pro-inflammatory cytokines. Furthermore, the anti-inflammatory effect of PN-101 was mediated by blockade of phosphorylation, nuclear translocation, and trans-activity of NFκB. Taken together, our results demonstrate that PN-101 has therapeutic potential to attenuate pathological inflammatory responses. [BMB Reports 2022; 55(3): 136-141].

Potential Therapeutic Effect of Micrornas in Extracellular Vesicles from Mesenchymal Stem Cells against SARS-CoV-2.

Extracellular vesicles (EVs) are cell-released, nanometer-scaled, membrane-bound materials and contain diverse contents including proteins, small peptides, and nucleic acids. Once released, EVs can alter the microenvironment and regulate a myriad of cellular physiology components, including cell-cell communication, proliferation, differentiation, and immune responses against viral infection. Among the cargoes in the vesicles, small non-coding micro-RNAs (miRNAs) have received attention in that they can regulate the expression of a variety of human genes as well as external viral genes via binding to the complementary mRNAs. In this study, we tested the potential of EVs as therapeutic agents for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. First, we found that the mesenchymal stem-cell-derived EVs (MSC-EVs) enabled the rescue of the cytopathic effect of SARS-CoV-2 virus and the suppression of proinflammatory responses in the infected cells by inhibiting the viral replication. We found that these anti-viral responses were mediated by 17 miRNAs matching the rarely mutated, conserved 3'-untranslated regions (UTR) of the viral genome. The top five miRNAs highly expressed in the MSC-EVs, miR-92a-3p, miR-26a-5p, miR-23a-3p, miR-103a-3p, and miR-181a-5p, were tested. They were bound to the complemented sequence which led to the recovery of the cytopathic effects. These findings suggest that the MSC-EVs are a potential candidate for multiple variants of anti-SARS-CoV-2.

Potent synthetic and endogenous ligands for the adopted orphan nuclear receptor Nurr1.

Until recently, Nurr1 (NR4A2) was known as an orphan nuclear receptor without a canonical ligand-binding domain, featuring instead a narrow and tight cavity for small molecular ligands to bind. In-depth characterization of its ligand-binding pocket revealed that it is highly dynamic, with its structural conformation changing more than twice on the microsecond-to-millisecond timescale. This observation suggests the possibility that certain ligands are able to squeeze into this narrow space, inducing a conformational change to create an accessible cavity. The cocrystallographic structure of Nurr1 bound to endogenous ligands such as prostaglandin E1/A1 and 5,6-dihydroxyindole contributed to clarifying the crucial roles of Nurr1 and opening new avenues for therapeutic interventions for neurodegenerative and/or inflammatory diseases related to Nurr1. This review introduces novel endogenous and synthetic Nurr1 agonists and discusses their potential effects in Nurr1-related diseases.

Effect of cysteine-free human fibroblast growth factor-5s mutant (FGF5sC93S) on hair growth.

Treatment for hair loss is largely limited, and any beneficial effects are often transient. Based on the critical role of the FGF5 isoform, FGF5s, in the hair growth cycle, it may be a good therapeutic candidate for the prevention of hair loss, as well as the promotion of hair growth. To investigate its potential use for hair growth, a mutant form of the FGF5s protein (FGF5sC93S) was generated, expressed, and purified. The FGF5sC93S mutant was able to antagonize FGF5-induced mitogenic activity, which normally triggers the conversion of hair follicles from the anagen phase to the catagen phase. In addition, the FGF5sC93S mutant efficiently suppressed gene expression induced by FGF5 both human outer root sheath (hORS) and human dermal papilla (hDP) cells. Administration of FGF5sC93S proteins onto the scalps of human subjects significantly increased the total number of hairs at 24 weeks. Together, our data demonstrate that a mutant form of the FGF5s protein could be used as a potential hair promoting agent.

PGE1 and PGA1 bind to Nurr1 and activate its transcriptional function.

The orphan nuclear receptor Nurr1 is critical for the development, maintenance and protection of midbrain dopaminergic (mDA) neurons. Here we show that prostaglandin E1 (PGE1) and its dehydrated metabolite, PGA1, directly interact with the ligand-binding domain (LBD) of Nurr1 and stimulate its transcriptional function. We also report the crystallographic structure of Nurr1-LBD bound to PGA1 at 2.05 Å resolution. PGA1 couples covalently to Nurr1-LBD by forming a Michael adduct with Cys566, and induces notable conformational changes, including a 21° shift of the activation function-2 helix (H12) away from the protein core. Furthermore, PGE1/PGA1 exhibit neuroprotective effects in a Nurr1-dependent manner, prominently enhance expression of Nurr1 target genes in mDA neurons and improve motor deficits in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned mouse models of Parkinson's disease. Based on these results, we propose that PGE1/PGA1 represent native ligands of Nurr1 and can exert neuroprotective effects on mDA neurons, via activation of Nurr1's transcriptional function.

Chloroquine modulates inflammatory autoimmune responses through Nurr1 in autoimmune diseases.

For over a half-century the anti-malarial drug chloroquine (CQ) has been used as a therapeutic agent, alone or in combination, to treat autoimmune diseases. However, neither the underlying mechanism(s) of action nor their molecular target(s) are well defined. The orphan nuclear receptor Nurr1 (also known as NR4A2) is an essential transcription factor affecting the development and maintenance of midbrain dopaminergic neurons. In this study, using in vitro T cell differentiation models, we demonstrate that CQ activates TREG cell differentiation and induces Foxp3 gene expression in a Nurr1-dependent manner. Remarkably, CQ appears to induce Nurr1 function by two distinct mechanisms: firstly, by direct binding to Nurr1's ligand-binding domain and promoting its transcriptional activity and secondly by upregulation of Nurr1 expression through the CREB signaling pathway. In contrast, CQ suppressed gene expression and differentiation of pathogenic TH17 cells. Importantly, using a valid animal model of inflammatory bowel disease (IBD), we demonstrated that CQ promotes Foxp3 expression and differentiation of TREG cells in a Nurr1-dependent manner, leading to significant improvement of IBD-related symptoms. Taken together, these data suggest that CQ ameliorates autoimmune diseases via regulating Nurr1 function/expression and that Nurr1 is a promising target for developing effective therapeutics of human inflammatory autoimmune diseases.

Dopamine neuron induction and the neuroprotective effects of thyroid hormone derivatives.

Parkinson's disease (PD) is a neurodegenerative disease characterized by progressive movement disturbances caused by the selective loss of dopamine (DA) neurons in the substantia nigra. Despite the identification of the causal mechanisms underlying the pathogenesis of PD, effective treatments remain elusive. In this study, we observed that a low level of fetal bovine serum (FBS) effectively induced DA neurons in rat neural precursor cells (NPCs) by enhancing nuclear receptor-related 1 protein (NURR1) expression. Among the various components of FBS, the thyroid hormones triiodothyronine (T3) and thyroxine (T4) were identified as key factors for the induction of DA neurons. Since an overdose of thyroid hormones can cause hyperthyroidism, we synthesized several thyroid hormone derivatives that can partially activate thyroid hormone receptors and induce the complete differentiation of NPCs into DA neurons. Two derivatives (#3 and #9) showed positive effects on the induction and maturation of DA neurons without showing significant affinity for the thyroid hormone receptor. They also effectively protected and restored DA neurons from neurotoxic insults. Taken together, these observations demonstrate that thyroid hormone derivatives can strongly induce DA neuron differentiation while avoiding excessive thyroid stimulation and might therefore be useful candidates for PD treatment.

Enhanced delivery of protein fused to cell penetrating peptides to mammalian cells.

Recent progress in cellular reprogramming technology and lineage-specific cell differentiation has provided great opportunities for translational research. Because virus-based gene delivery is not a practical reprogramming protocol, protein-based reprogramming has been receiving attention as a safe way to generate reprogrammed cells. However, the poor efficiency of the cellular uptake of reprogramming proteins is still a major obstacle. Here, we reported key factors which improve the cellular uptake of these proteins. Purified red fluorescent proteins fused with 9xLysine (dsRED-9K) as a cell penetrating peptide were efficiently delivered into the diverse primary cells. Protein delivery was improved by the addition of amodiaquine. Furthermore, purified dsRED-9K was able to penetrate all cell lineages derived from mouse embryonic stem cells efficiently. Our data may provide important insights into the design of protein-based reprogramming or differentiation protocols [BMB Reports 2019; 52(5): 324-329].

Purification of functional reprogramming factors in mammalian cell using FLAG -Tag.

Induced pluripotent stem cells (iPSCs) technology is a method for generating pluripotent stem cells in vitro from fully differentiated cells such as fibroblast cells. The potential applications of iPSC technology in cell therapy and disease modeling could influence current medical practices. Despite current advances in iPSC technology, many patient-derived reprogrammed cells are not suitable for clinical trial because most protocols rely on virus-based techniques, which pose the risk of integration of the viral genome into the chromosomes. Therefore, non-viral methods such as mRNA and protein-based reprogramming are promising alternatives when generating clinically safe iPSCs. In a previous study, we generated human iPSCs using cell extracts with cell penetration peptide (CPP) for the delivery of reprogramming proteins [Kim et al. Cell Stem Cells, 2009]. In here, we show that the expression of reprogramming factors in mammalian cells and subsequent purification of these factors by FLAG-Tag could reprogram fibroblasts into iPSCs.

Efficient Generation of Dopamine Neurons by Synthetic Transcription Factor mRNAs.

Generation of functional dopamine (DA) neurons is an essential step for the development of effective cell therapy for Parkinson's disease (PD). The generation of DA neurons can be accomplished by overexpression of DA-inducible genes using virus- or DNA-based gene delivery methods. However, these gene delivery methods often cause chromosomal anomalies. In contrast, mRNA-based gene delivery avoids this problem and therefore is considered safe to use in the development of cell-based therapy. Thus, we used mRNA-based gene delivery method to generate safe DA neurons. In this study, we generated transformation-free DA neurons by transfection of mRNA encoding DA-inducible genes Nurr1 and FoxA2. The delivery of mRNA encoding dopaminergic fate inducing genes proved sufficient to induce naive rat forebrain precursor cells to differentiate into neurons exhibiting the biochemical, electrophysiological, and functional properties of DA neurons in vitro. Additionally, the generation efficiency of DA neurons was improved by the addition of small molecules, db-cAMP, and the adjustment of transfection timing. The successful generation of DA neurons using an mRNA-based method offers the possibility of developing clinical-grade cell sources for neuronal cell replacement treatment for PD.

Metabolic control of primed human pluripotent stem cell fate and function by the miR-200c-SIRT2 axis.

A hallmark of cancer cells is the metabolic switch from oxidative phosphorylation (OXPHOS) to glycolysis, a phenomenon referred to as the 'Warburg effect', which is also observed in primed human pluripotent stem cells (hPSCs). Here, we report that downregulation of SIRT2 and upregulation of SIRT1 is a molecular signature of primed hPSCs and that SIRT2 critically regulates metabolic reprogramming during induced pluripotency by targeting glycolytic enzymes including aldolase, glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, and enolase. Remarkably, knockdown of SIRT2 in human fibroblasts resulted in significantly decreased OXPHOS and increased glycolysis. In addition, we found that miR-200c-5p specifically targets SIRT2, downregulating its expression. Furthermore, SIRT2 overexpression in hPSCs significantly affected energy metabolism, altering stem cell functions such as pluripotent differentiation properties. Taken together, our results identify the miR-200c-SIRT2 axis as a key regulator of metabolic reprogramming (Warburg-like effect), via regulation of glycolytic enzymes, during human induced pluripotency and pluripotent stem cell function.