Cisd2 deficiency drives premature aging and causes mitochondria-mediated defects in mice

High-grade serous carcinoma of the fallopian tube in a young woman with chromosomal 4q abnormality: A case report

BACKGROUND

Few studies have reported an association between an increased risk of acquiring cancers and survival in patients with 4q deletion syndrome. This study presents a rare association between chromosome 4q abnormalities and fallopian tube high-grade serous carcinoma (HGSC) in a young woman.

CASE SUMMARY

A 35-year-old woman presented with acute dull abdominal pain and a known chromosomal abnormality involving 4q13.3 duplication and 4q23q24 deletion. Upon arrival at the emergency room, her abdomen appeared ovoid and distended with palpable shifting dullness. Ascites were identified through abdominal ultrasound, and computed tomography revealed an omentum cake and an enlarged bilateral adnexa. Blood tests showed elevated CA-125 levels. Paracentesis was conducted, and immunohistochemistry indicated that the cancer cells favored an ovarian origin, making us suspect ovarian cancer. The patient underwent debulking surgery, which led to a diagnosis of stage IIIC HGSC of the fallopian tube. Subsequently, the patient received adjuvant chemotherapy with carboplatin and paclitaxel, resulting in stable current condition.

CONCLUSION

This study demonstrates a rare correlation between a chromosome 4q abnormality and HGSC. UBE2D3 may affect crucial cancer-related pathways, including P53, BRCA, cyclin D, and tyrosine kinase receptors, thereby possibly contributing to cancer development. In addition, ADH1 and DDIT4 may be potential influencers of both carcinogenic and therapeutic responses.

Diacylglycerol O-acyltransferase (DGAT) isoforms play a role in peridroplet mitochondrial fatty acid metabolism in bovine liver

Hepatocellular lipid accumulation characterizes fatty liver in dairy cows. Lipid droplets (LD), specialized organelles that store lipids and maintain cellular lipid homeostasis, are responsible for the ectopic storage of lipids associated with several metabolic disorders. In recent years, non-ruminant studies have reported that LD-mitochondria interactions play an important role in lipid metabolism. Due to the role of diacylglycerol acyltransferase isoforms (DGAT1 and DGAT2) in LD synthesis, we explored mechanisms of mitochondrial fatty acid transport in ketotic cows using liver biopsies and isolated primary hepatocytes. Compared with healthy cows, cows with fatty liver had massive accumulation of LD and high protein expression of the triglyceride (TAG) synthesis-related enzymes DGAT1 and DGAT2, LD synthesis-related proteins perilipin 2 (PLIN2) and perilipin 5 (PLIN5), and the mitochondrial fragmentation-related proteins dynamin-related protein 1 (DRP1) and fission 1 (FIS1). In contrast, factors associated with fatty acid oxidation, mitochondrial fusion and mitochondrial electron transport chain complex were lower compared with those in the healthy cows. In addition, transmission electron microscopy revealed significant contacts between LD-mitochondria in liver tissue from cows with fatty liver. Compared with isolated cytoplasmic mitochondria, expression of carnitine palmitoyl transferase 1A (CPT1A) and DRP1 was lower, but mitofusin 2 (MFN2) and mitochondrial electron transport chain complex was greater in isolated peridroplet mitochondria from hepatic tissue of cows with fatty liver. In vitro data indicated that exogenous free fatty acids (FFA) induced hepatocyte LD synthesis and mitochondrial dynamics consistent with in vivo results. Furthermore, DGAT2 inhibitor treatment attenuated the FFA-induced upregulation of PLIN2 and PLIN5 and rescued the impairment of mitochondrial dynamics. Inhibition of DGAT2 also restored mitochondrial membrane potential and reduced hepatocyte reactive oxygen species production. The present in vivo and in vitro results indicated there are functional differences among different types of mitochondria in the liver tissue of dairy cows with ketosis. Activity of DGAT2 may play a key role in maintaining liver mitochondrial function and lipid homeostasis in dairy cows during the transition period.

CISD3/MiNT is required for complex I function, mitochondrial integrity, and skeletal muscle maintenance

Mitochondria play a central role in muscle metabolism and function. A unique family of iron-sulfur proteins, termed CDGSH Iron Sulfur Domain-containing (CISD/NEET) proteins, support mitochondrial function in skeletal muscles. The abundance of these proteins declines during aging leading to muscle degeneration. Although the function of the outer mitochondrial CISD/NEET proteins, CISD1/mitoNEET and CISD2/NAF-1, has been defined in skeletal muscle cells, the role of the inner mitochondrial CISD protein, CISD3/MiNT, is currently unknown. Here, we show that CISD3 deficiency in mice results in muscle atrophy that shares proteomic features with Duchenne muscular dystrophy. We further reveal that CISD3 deficiency impairs the function and structure of skeletal muscles, as well as their mitochondria, and that CISD3 interacts with, and donates its [2Fe-2S] clusters to, complex I respiratory chain subunit NADH Ubiquinone Oxidoreductase Core Subunit V2 (NDUFV2). Using coevolutionary and structural computational tools, we model a CISD3-NDUFV2 complex with proximal coevolving residue interactions conducive of [2Fe-2S] cluster transfer reactions, placing the clusters of the two proteins 10 to 16 Å apart. Taken together, our findings reveal that CISD3/MiNT is important for supporting the biogenesis and function of complex I, essential for muscle maintenance and function. Interventions that target CISD3 could therefore impact different muscle degeneration syndromes, aging, and related conditions.

Iron-sulfur protein odyssey: exploring their cluster functional versatility and challenging identification

Iron-sulfur (Fe-S) clusters are an essential and ubiquitous class of protein-bound prosthetic centers that are involved in a broad range of biological processes (e.g. respiration, photosynthesis, DNA replication and repair and gene regulation) performing a wide range of functions including electron transfer, enzyme catalysis, and sensing. In a general manner, Fe-S clusters can gain or lose electrons through redox reactions, and are highly sensitive to oxidation, notably by small molecules such as oxygen and nitric oxide. The [2Fe-2S] and [4Fe-4S] clusters, the most common Fe-S cofactors, are typically coordinated by four amino acid side chains from the protein, usually cysteine thiolates, but other residues (e.g. histidine, aspartic acid) can also be found. While diversity in cluster coordination ensures the functional variety of the Fe-S clusters, the lack of conserved motifs makes new Fe-S protein identification challenging especially when the Fe-S cluster is also shared between two proteins as observed in several dimeric transcriptional regulators and in the mitoribosome. Thanks to the recent development of in cellulo, in vitro, and in silico approaches, new Fe-S proteins are still regularly identified, highlighting the functional diversity of this class of proteins. In this review, we will present three main functions of the Fe-S clusters and explain the difficulties encountered to identify Fe-S proteins and methods that have been employed to overcome these issues.

Cisd2 deficiency impairs neutrophil function by regulating calcium homeostasis via Calnexin and SERCA

In the context of aging, the susceptibility to infectious diseases increases, leading to heightened morbidity and mortality. This phenomenon, termed immunosenescence, is characterized by dysregulation in the aging immune system, including abnormal alterations in lymphocyte composition, elevated basal inflammation, and the accumulation of senescent T cells. Such changes contribute to increased autoimmune diseases, enhanced infection severity, and reduced responsiveness to vaccines. Utilizing aging animal models becomes imperative for a comprehensive understanding of immunosenescence, given the complexity of aging as a physiological process in living organisms. Our investigation focuses on Cisd2, a causative gene for Wolfram syndrome, to elucidate on immunosenescence. Cisd2 knockout (KO) mice, serving as a model for premature aging, exhibit a shortened lifespan with early onset of aging-related features, such as decreased bone density, hair loss, depigmentation, and optic nerve degeneration. Intriguingly, we found that the Cisd2 KO mice present a higher number of neutrophils in the blood; however, isolated neutrophils from these mice display functional defects. Through mass spectrometry analysis, we identified an interaction between Cisd2 and Calnexin, a protein known for its role in protein quality control. Beyond this function, Calnexin also regulates calcium homeostasis through interaction with sarcoendoplasmic reticulum calcium transport ATPase (SERCA). Our study proposes that Cisd2 modulates calcium homeostasis via its interaction with Calnexin and SERCA, consequently influencing neutrophil functions. [BMB Reports 2024; 57(5): 256-261].

Adolescent Stress-Induced Ventral Hippocampus Redox Dysregulation Underlies Behavioral Deficits and Excitatory/Inhibitory Imbalance Related to Schizophrenia

BACKGROUND AND HYPOTHESIS

Redox dysregulation has been proposed as a convergent point of childhood trauma and the emergence of psychiatric disorders, such as schizophrenia (SCZ). A critical region particularly vulnerable to environmental insults during adolescence is the ventral hippocampus (vHip). However, the impact of severe stress on vHip redox states and their functional consequences, including behavioral and electrophysiological changes related to SCZ, are not entirely understood.

STUDY DESIGN

After exposing adolescent animals to physical stress (postnatal day, PND31-40), we explored social and cognitive behaviors (PND47-49), the basal activity of pyramidal glutamate neurons, the number of parvalbumin (PV) interneurons, and the transcriptomic signature of the vHip (PND51). We also evaluated the impact of stress on the redox system, including mitochondrial respiratory function, reactive oxygen species (ROS) production, and glutathione (GSH) levels in the vHip and serum.

STUDY RESULTS

Adolescent-stressed animals exhibited loss of sociability, cognitive impairment, and vHip excitatory/inhibitory (E/I) imbalance. Genome-wide transcriptional profiling unveiled the impact of stress on redox system- and synaptic-related genes. Stress impacted mitochondrial respiratory function and changes in ROS levels in the vHip. GSH and glutathione disulfide (GSSG) levels were elevated in the serum of stressed animals, while GSSG was also increased in the vHip and negatively correlated with sociability. Additionally, PV interneuron deficits in the vHip caused by adolescent stress were associated with oxidative stress.

CONCLUSIONS

Our results highlight the negative impact of adolescent stress on vHip redox regulation and mitochondrial function, which are partially associated with E/I imbalance and behavioral abnormalities related to SCZ.

Hesperetin activates CISD2 to attenuate senescence in human keratinocytes from an older person and rejuvenates naturally aged skin in mice

BACKGROUND

CDGSH iron-sulfur domain-containing protein 2 (CISD2), a pro-longevity gene, mediates healthspan in mammals. CISD2 is down-regulated during aging. Furthermore, a persistently high level of CISD2 promotes longevity and ameliorates an age-related skin phenotype in transgenic mice. Here we translate the genetic evidence into a pharmaceutical application using a potent CISD2 activator, hesperetin, which enhances CISD2 expression in HEK001 human keratinocytes from an older person. We also treated naturally aged mice in order to study the activator's anti-aging efficacy.

METHODS

We studied the biological effects of hesperetin on aging skin using, firstly, a cell-based platform, namely a HEK001 human keratinocyte cell line established from an older person. Secondly, we used a mouse model, namely old mice at 21-month old. In the latter case, we investigate the anti-aging efficacy of hesperetin on ultraviolet B (UVB)-induced photoaging and naturally aged skin. Furthermore, to identify the underlying mechanisms and potential biological pathways involved in this process we carried out transcriptomic analysis. Finally, CISD2 knockdown HEK001 keratinocytes and Cisd2 knockout mice were used to study the Cisd2-dependent effects of hesperetin on skin aging.

RESULTS

Four findings are pinpointed. Firstly, in human skin, CISD2 is mainly expressed in proliferating keratinocytes from the epidermal basal layer and, furthermore, CISD2 is down-regulated in the sun-exposed epidermis. Secondly, in HEK001 human keratinocytes from an older person, hesperetin enhances mitochondrial function and protects against reactive oxygen species-induced oxidative stress via increased CISD2 expression; this enhancement is CISD2-dependent. Additionally, hesperetin alleviates UVB-induced damage and suppresses matrix metalloproteinase-1 expression, the latter being a major indicator of UVB-induced damage in keratinocytes. Thirdly, transcriptomic analysis revealed that hesperetin modulates a panel of differentially expressed genes that are associated with mitochondrial function, redox homeostasis, keratinocyte function, and inflammation in order to attenuate senescence. Intriguingly, hesperetin activates two known longevity-associated regulators, namely FOXO3a and FOXM1, in order to suppress the senescence-associated secretory phenotype. Finally, in mouse skin, hesperetin enhances CISD2 expression to ameliorate UVB-induced photoaging and this occurs via a mechanism involving CISD2. Most strikingly, late-life treatment with hesperetin started at 21-month old and lasting for 5 months, is able to retard skin aging and rejuvenate naturally aged skin in mice.

CONCLUSIONS

Our results reveal that a pharmacological elevation of CISD2 expression at a late-life stage using hesperetin treatment is a feasible approach to effectively mitigating both intrinsic and extrinsic skin aging and that hesperetin could act as a functional food or as a skincare product for fighting skin aging.

CISD2 promotes lung squamous carcinoma cell migration and invasion via the TGF-β1-induced Smad2/3 signaling pathway

BACKGROUND

Although aberrant expression of CDGSH iron sulfur domain 2 (CISD2) contributes to the tumorigenesis and progression of numerous human cancers, the biological function of CISD2 and its specific prognostic value in lung squamous cell carcinoma (LUSC) have yet to be comprehensively explored. The current study aimed to elucidate the role of CISD2 in LUSC as well as the underlying molecular mechanisms.

METHODS

Immunohistochemistry was conducted to detect the protein expression of CISD2 and analyze whether high expression of CISD2 affects the overall survival (OS) of LUSC patients. Cell proliferation, colony formation, wound healing and Transwell invasion assays were performed to clarify whether CISD2 contributes to LUSC cell proliferation and disease progression. Quantitative real-time reverse transcription-PCR and western blot assays were used to detect the levels of transcription factors and key epithelial-mesenchymal transition (EMT)-related markers in LUSC cells after CISD2 knockdown and overexpression to determine whether CISD2 regulates transforming growth factor-beta (TGF-β)-induced EMT in LUSC.

RESULTS

Immunohistochemistry of human tissue microarrays containing 90 pairs of adjacent and cancerous tissues revealed that CISD2 is considerably overexpressed in LUSC and strongly linked to poor OS. Functional experiments suggested that silencing endogenous CISD2 inhibited the growth, colony formation, migration, and invasion of H2170 and H226 cell lines. Exogenous overexpression of CISD2 facilitated these phenotypes in SK-MES-1 and H2170 cells. Furthermore, CISD2 promoted EMT progression by increasing the expression of mesenchymal markers (N-cadherin, vimentin, Snail, and Slug) as well as SMAD2/3 and reducing the expression of the epithelial marker E-cadherin. Mechanistically, our studies provide the first evidence that CISD2 can promote EMT by enhancing TGF-β1-induced Smad2/3 expression in LUSC cells.

CONCLUSION

In conclusion, our research illustrates that CISD2 is highly expressed in LUSC and may facilitate LUSC proliferation and metastasis. Thus, CISD2 may serve as an independent prognostic marker and possible treatment target for LUSC.

Wolfram Syndrome-2, a Cause of Severe Gastrointestinal Bleeding: A Case Series and a Literature Review

Background

There are very few reports of Wolfram syndrome-2 (WFS2) in the literature, and understanding of involvement of the gastrointestinal (GI) tract in the syndrome is limited. Objectives: This study aims to describe the clinical presentations of a large number of WFS2 patients with specific focus on their GI manifestations.

Methods

This is a retrospective case series study. Patients who were homozygous for the CISD2 gene mutation were identified through the genetic department of Al-Makassed hospital. Their medical records were reviewed, and biometric data have been obtained. The data were collected and arranged on a data sheet, and descriptive analysis was done using SPSS.

Results

Thirteen patients from 9 families were identified; diabetes mellitus was present in 6 of them, optic atrophy in 5, diabetes insipidus (DI) in 5, and deafness in 2. All of the patients had GI manifestations with abnormal findings on upper endoscopy. Dysmorphic facial features and abnormal findings on brain MRI were present in 3 of our patients. The GI manifestations including GI bleeding and severe ulcerations were the first to appear in 9 of them, while anemia in the remaining 4.

Conclusion

This is the largest study to date describing patients with WFS2. This study's evidence shows the prominent presence of GI involvement, and the severe findings on endoscopy, including duodenal, gastric, and esophageal ulcerations and strictures. Unlike in the Jordanian report, some of the patients in our report also have DI.

Upregulation of CDGSH iron sulfur domain 2 attenuates cerebral ischemia/reperfusion injury

CDGSH iron sulfur domain 2 can inhibit ferroptosis, which has been associated with cerebral ischemia/reperfusion, in individuals with head and neck cancer. Therefore, CDGSH iron sulfur domain 2 may be implicated in cerebral ischemia/reperfusion injury. To validate this hypothesis in the present study, we established mouse models of occlusion of the middle cerebral artery and HT22 cell models of oxygen-glucose deprivation and reoxygenation to mimic cerebral ischemia/reperfusion injury in vivo and in vitro, respectively. We found remarkably decreased CDGSH iron sulfur domain 2 expression in the mouse brain tissue and HT22 cells. When we used adeno-associated virus and plasmid to up-regulate CDGSH iron sulfur domain 2 expression in the brain tissue and HT22 cell models separately, mouse neurological dysfunction was greatly improved; the cerebral infarct volume was reduced; the survival rate of HT22 cells was increased; HT22 cell injury was alleviated; the expression of ferroptosis-related glutathione peroxidase 4, cystine-glutamate antiporter, and glutathione was increased; the levels of malondialdehyde, iron ions, and the expression of transferrin receptor 1 were decreased; and the expression of nuclear-factor E2-related factor 2/heme oxygenase 1 was increased. Inhibition of CDGSH iron sulfur domain 2 upregulation via the nuclear-factor E2-related factor 2 inhibitor ML385 in oxygen-glucose deprived and reoxygenated HT22 cells blocked the neuroprotective effects of CDGSH iron sulfur domain 2 up-regulation and the activation of the nuclear-factor E2-related factor 2/heme oxygenase 1 pathway. Our data indicate that the up-regulation of CDGSH iron sulfur domain 2 can attenuate cerebral ischemia/reperfusion injury, thus providing theoretical support from the perspectives of cytology and experimental zoology for the use of this protein as a therapeutic target in patients with cerebral ischemia/reperfusion injury.

Discovery of tetrasubstituted thiophenes as Cisd2 activators: A potential novel therapeutic option in nonalcoholic fatty liver disease

Down-regulation of Cisd2 in the liver has been implicated in the development of nonalcoholic fatty liver disease (NAFLD) and increasing the level of Cisd2 is therefore a potential therapeutic approach to this group of diseases. Herein, we describe the design, synthesis, and biological evaluation of a series of Cisd2 activators, all thiophene analogs, based on a hit obtained using two-stage screening and prepared via either the Gewald reaction or by intramolecular aldol-type condensation of an N,S-acetal. Metabolic stability studies of the resulting potent Cisd2 activators suggest that thiophenes 4q and 6 are suitable for in vivo studies. The results from studies on 4q-treated and 6-treated Cisd2hKO-het mice, which carry a heterozygous hepatocyte-specific Cisd2 knockout, confirm that (1) there is a correlation between Cisd2 levels and NAFLD and (2) these compounds have the ability to prevent, without detectable toxicity, the development and progression of NAFLD.

Targeting Ca2+-dependent pathways to promote corneal epithelial wound healing induced by CISD2 deficiency

Chronic epithelial defects of the cornea, which are usually associated with severe dry eye disease, diabetes mellitus, chemical injuries or neurotrophic keratitis, as well as aging, are an unmet clinical need. CDGSH Iron Sulfur Domain 2 (CISD2) is the causative gene for Wolfram syndrome 2 (WFS2; MIM 604928). CISD2 protein is significantly decreased in the corneal epithelium of patients with various corneal epithelial diseases. Here we summarize the most updated publications and discuss the central role of CISD2 in corneal repair, as well as providing new results describing how targeting Ca²⁺-dependent pathways can improve corneal epithelial regeneration. This review mainly focuses on the following topics. Firstly, an overview of the cornea and of corneal epithelial wound healing. The key players involved in this process, such as Ca²⁺, various growth factors/cytokines, extracellular matrix remodeling, focal adhesions and proteinases, are briefly discussed. Secondly, it is well known that CISD2 plays an essential role in corneal epithelial regeneration via the maintenance of intracellular Ca²⁺ homeostasis. CISD2 deficiency dysregulates cytosolic Ca²⁺, impairs cell proliferation and migration, decreases mitochondrial function and increases oxidative stress. As a consequence, these abnormalities bring about poor epithelial wound healing and this, in turn, will lead to persistent corneal regeneration and limbal progenitor cell exhaustion. Thirdly, CISD2 deficiency induces three distinct Ca²⁺-dependent pathways, namely the calcineurin, CaMKII and PKCα signaling pathways. Intriguingly, inhibition of each of the Ca²⁺-dependent pathways seems to reverse cytosolic Ca²⁺ dysregulation and restore cell migration during corneal wound healing. Notably, cyclosporin, an inhibitor of calcineurin, appears to have a dual effect on both inflammatory and corneal epithelial cells. Finally, corneal transcriptomic analyses have revealed that there are six major functional groupings of differential expression genes when CISD2 deficiency is present: (1) inflammation and cell death; (2) cell proliferation, migration and differentiation; (3) cell adhesion, junction and interaction; (4) Ca²⁺ homeostasis; (5) wound healing and extracellular matrix; and (6) oxidative stress and aging. This review highlights the importance of CISD2 in corneal epithelial regeneration and identifies the potential of repurposing venerable FDA-approved drugs that target Ca²⁺-dependent pathways for new uses, namely treating chronic epithelial defects of the cornea.

Delivery of low-density lipoprotein from endocytic carriers to mitochondria supports steroidogenesis

The low-density lipoprotein (LDL) is a major cholesterol carrier in circulation and is internalized into cells through LDL receptor (LDLR)-mediated endocytosis. The LDLR protein is highly expressed in the steroidogenic organs and LDL cholesterol is an important source for steroidogenesis. Cholesterol must be transported into the mitochondria, where steroid hormone biosynthesis initiates. However, how LDL cholesterol is conveyed to the mitochondria is poorly defined. Here, through genome-wide small hairpin RNA screening, we find that the outer mitochondrial membrane protein phospholipase D6 (PLD6), which hydrolyses cardiolipin to phosphatidic acid, accelerates LDLR degradation. PLD6 promotes the entrance of LDL and LDLR into the mitochondria, where LDLR is degraded by mitochondrial proteases and LDL-carried cholesterol is used for steroid hormone biosynthesis. Mechanistically, the outer mitochondrial membrane protein CISD2 binds to the cytosolic tail of LDLR and tethers LDLR⁺ vesicles to the mitochondria. The fusogenic lipid phosphatidic acid generated by PLD6 facilitates the membrane fusion of LDLR⁺ vesicles with the mitochondria. This intracellular transport pathway of LDL-LDLR bypasses the lysosomes and delivers cholesterol to the mitochondria for steroidogenesis.

Ferroptosis-associated gene CISD2 suppresses colon cancer development by regulating tumor immune microenvironment

Background

Despite the association of ferroptosis with various tumors, the specific mechanism by which it influences colon adenocarcinoma (COAD) microenvironmental equilibrium remains elusive. This study aims to elucidate how ferroptosis affects COAD microenvironmental homeostasis and its potential impact on COAD research.

Objective

By employing genetic screening and single-cell analysis of tumor data, we investigated the role of ferroptosis genes in COAD microenvironmental homeostasis. The genes were correlated with immune cell infiltration in tissue samples and patient outcomes.

Methods

Ferroptosis-associated genes were initially identified through the FerrDb database. Utilizing the tidyverse and Seurat packages, genes with substantial expression differences were extracted, and clustering analysis was performed on the single-cell data. A Venn diagram depicted shared differential genes for ferroptosis and tumors. To screen key ferroptosis genes, further enrichment analysis and immune cell infiltration analysis were conducted. Lastly, human COAD cell lines were employed to overexpress CDGSH iron sulfur domain 2 (CISD2) through cellular assays to validate its function in COAD.

Results

Following screening of The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases, 414 COAD patient samples and 341 normal samples were included. Through the FerrDb database, 259 ferroptosis genes were identified. Clustering the single-cell data revealed 911 tumor marker genes, of which 18 were ferroptosis genes. Analysis of variance (ANOVA) and univariate regression analysis determined that only CISD2 was statistically significantly associated with clinical outcomes. Additionally, CISD2 was found to positively correlate with activated memory T cells and negatively correlate with regulatory T cells (Tregs) and plasma cells in COAD, as well as being significantly associated with several immune-related and cancer-related pathways. CISD2 expression was elevated in most tumors, likely due to cell cycle regulation and immune system activation. Moreover, CISD2 upregulation inhibited COAD cell proliferation and enhanced 5-fluorouracil (5-FU) sensitivity. Our findings indicate, for the first time, that CISD2 governs the cell cycle and stimulates the immune system to impede COAD progression.

Conclusion

By modulating the cell cycle and mediating immune infiltration, CISD2 may inhibit COAD development by influencing tumor immune microenvironment equilibrium, providing valuable insights into the relevance and potential impact of the research results on the COAD research field.

CISD3 is required for Complex I function, mitochondrial integrity, and skeletal muscle maintenance

Mitochondria play a central role in muscle metabolism and function. In skeletal muscles, a unique family of iron-sulfur proteins, termed CISD proteins, support mitochondrial function. The abundance of these proteins declines with aging leading to muscle degeneration. Although the function of the outer mitochondrial proteins CISD1 and CISD2 has been defined, the role of the inner mitochondrial protein CISD3, is currently unknown. Here we show that CISD3 deficiency in mice results in muscle atrophy that shares proteomic features with Duchenne Muscular Dystrophy. We further reveal that CISD3 deficiency impairs the function and structure of skeletal muscle mitochondria, and that CISD3 interacts with, and donates its clusters to, Complex I respiratory chain subunit NDUFV2. These findings reveal that CISD3 is important for supporting the biogenesis and function of Complex I, essential for muscle maintenance and function. Interventions that target CISD3 could therefore impact muscle degeneration syndromes, aging, and related conditions.

1H, 13C and 15N assignment of the human mitochondrial paramagnetic iron-sulfur protein CISD3

CISD3 is a mitochondrial protein that contains two [2Fe-2S] clusters. This protein is overexpressed in some types of cancer, so it has emerged as a potential drug target. A detailed characterization of this protein is crucial to understand how CISD3 is involved in these physiopathologies. In this study, isotopically labeled human CISD3 was expressed in Escherichia coli. A set of double and triple resonance experiments performed with standard parameters/datasets provided the assignment of 40% of the HN resonances, 47% of Cα, and 46% of C' resonances. Tailored paramagnetic HSQC, CON and CACO experiments extended up to 59% for HN, 70% for Cα and 69% for C'. The ¹H, ¹³C and ¹⁵N NMR chemical shift assignment of human CISD3 is reported here.

Metadynamics simulations of ligands binding to protein surfaces: a novel tool for rational drug design

Structure-based drug design protocols may encounter difficulties to investigate poses when the biomolecular targets do not exhibit typical binding pockets. In this study, by providing two concrete examples from our labs, we suggest that the combination of metadynamics free energy methods (validated against affinity measurements), along with experimental structural information (by X-ray crystallography and NMR), can help to identify the poses of ligands on protein surfaces. The simulation workflow proposed here was implemented in a widely used code, namely GROMACS, and it could straightforwardly be applied to various drug-design campaigns targeting ligands' binding to protein surfaces.

Depletion of WFS1 compromises mitochondrial function in hiPSC-derived neuronal models of Wolfram syndrome

Mitochondrial dysfunction involving mitochondria-associated ER membrane (MAM) dysregulation is implicated in the pathogenesis of late-onset neurodegenerative diseases, but understanding is limited for rare early-onset conditions. Loss of the MAM-resident protein WFS1 causes Wolfram syndrome (WS), a rare early-onset neurodegenerative disease that has been linked to mitochondrial abnormalities. Here we demonstrate mitochondrial dysfunction in human induced pluripotent stem cell-derived neuronal cells of WS patients. VDAC1 is identified to interact with WFS1, whereas loss of this interaction in WS cells could compromise mitochondrial function. Restoring WFS1 levels in WS cells reinstates WFS1-VDAC1 interaction, which correlates with an increase in MAMs and mitochondrial network that could positively affect mitochondrial function. Genetic rescue by WFS1 overexpression or pharmacological agents modulating mitochondrial function improves the viability and bioenergetics of WS neurons. Our data implicate a role of WFS1 in regulating mitochondrial functionality and highlight a therapeutic intervention for WS and related rare diseases with mitochondrial defects.

FTD-associated behavioural and transcriptomic abnormalities in 'humanized' progranulin-deficient mice: A novel model for progranulin-associated FTD

Frontotemporal dementia (FTD) is an early onset dementia characterized by neuropathology and behavioural changes. A common genetic cause of FTD is haploinsufficiency of the gene progranulin (GRN). Mouse models of progranulin deficiency have provided insight into progranulin neurobiology, but the description of phenotypes with preclinical relevance has been limited in the currently available heterozygous progranulin-null mice. The identification of robust and reproducible FTD-associated behavioural, neuropathological, and biochemical phenotypes in progranulin deficient mice is a critical step in the preclinical development of therapies for FTD. In this work, we report the generation of a novel, 'humanized' mouse model of progranulin deficiency that expresses a single, targeted copy of human GRN in the absence of mouse progranulin. We also report the in-depth, longitudinal characterization of humanized progranulin-deficient mice and heterozygous progranulin-null mice over 18 months. Our analysis yielded several novel progranulin-dependent physiological and behavioural phenotypes, including increased marble burying, open field hyperactivity, and thalamic microgliosis in both models. RNAseq analysis of cortical tissue revealed an overlapping profile of transcriptomic dysfunction. Further transcriptomic analysis offers new insights into progranulin neurobiology. In sum, we have identified several consistent phenotypes in two independent mouse models of progranulin deficiency that are expected to be useful endpoints in the development of therapies for progranulin-deficient FTD. Furthermore, the presence of the human progranulin gene in the humanized progranulin-deficient mice will expedite the development of clinically translatable gene therapy strategies.

Loss of forebrain BIN1 attenuates hippocampal pathology and neuroinflammation in a tauopathy model

Bridging integrator 1 (BIN1) is the second most prevalent genetic risk factor identified by genome-wide association studies (GWAS) for late-onset Alzheimer's disease. BIN1 encodes an adaptor protein that regulates membrane dynamics in the context of endocytosis and neurotransmitter vesicle release. In vitro evidence suggests that BIN1 can directly bind to tau in the cytosol. In addition, BIN1's function limits extracellular tau seed uptake by endocytosis and subsequent propagation as well as influences tau release through exosomes. However, the in vivo roles of BIN1 in tau pathogenesis and tauopathy-mediated neurodegeneration remain uncharacterized. We generated conditional knockout mice with a selective loss of Bin1 expression in the forebrain excitatory neurons and oligodendrocytes in P301S human tau transgenic background (line PS19). PS19 mice develop age-dependent tau neuropathology and motor deficits and are commonly used to study Alzheimer's disease tau pathophysiology. The severity of motor deficits and neuropathology was compared between experimental and control mice that differ with respect to forebrain BIN1 expression. BIN1's involvement in tau pathology and neuroinflammation was quantified by biochemical methods and immunostaining. Transcriptome changes were profiled by RNA-sequencing analysis to gain molecular insights. The loss of forebrain BIN1 expression in PS19 mice exacerbated tau pathology in the somatosensory cortex, thalamus, spinal cord and sciatic nerve, accelerated disease progression and caused early death. Intriguingly, the loss of BIN1 also mitigated tau neuropathology in select regions, including the hippocampus, entorhinal/piriform cortex, and amygdala, thus attenuating hippocampal synapse loss, neuronal death, neuroinflammation and brain atrophy. At the molecular level, the loss of forebrain BIN1 elicited complex neuronal and non-neuronal transcriptomic changes, including altered neuroinflammatory gene expression, concomitant with an impaired microglial transition towards the disease-associated microglial phenotype. These results provide crucial new information on in vivo BIN1 function in the context of tau pathogenesis. We conclude that forebrain neuronal BIN1 expression promotes hippocampal tau pathogenesis and neuroinflammation. Our findings highlight an exciting region specificity in neuronal BIN1 regulation of tau pathogenesis and reveal cell-autonomous and non-cell-autonomous mechanisms involved in BIN1 modulation of tau neuropathology.

Calcium signaling and genetic rare diseases: An auditory perspective

Deafness is a highly heterogeneous disorder which stems, for 50%, from genetic origins. Sensory transduction relies mainly on sensory hair cells of the cochlea, in the inner ear. Calcium is key for the function of these cells and acts as a fundamental signal transduction. Its homeostasis depends on three factors: the calcium influx, through the mechanotransduction channel at the apical pole of the hair cell as well as the voltage-gated calcium channel at the base of the cells; the calcium buffering via Ca²⁺-binding proteins in the cytoplasm, but also in organelles such as mitochondria and the reticulum endoplasmic mitochondria-associated membranes with specialized proteins; and the calcium extrusion through the Ca-ATPase pump, located all over the plasma membrane. In addition, the synaptic transmission to the central nervous system is also controlled by calcium. Genetic studies of inherited deafness have tremendously helped understand the underlying molecular pathways of calcium signaling. In this review, we discuss these different factors in light of the associated genetic diseases (syndromic and non-syndromic deafness) and the causative genes.

Multiple mechanisms of curcumin targeting spinal cord injury

Spinal cord injury (SCI) is an irreversible disease process with a high disability and mortality rate. After primary spinal cord injury, the secondary injury may occur in sequence, which is composed of ischemia and hypoxia, excitotoxicity, calcium overload, oxidative stress and inflammation, resulting in massive death of parenchymal cells in the injured area, followed by the formation of syringomyelia. Effectively curbing the process of secondary injury can promote nerve repair and improve functional prognosis. As the main active ingredient in turmeric, curcumin can play an important role in reducing inflammation and oxidation, protecting the neurons, and ultimately reducing spinal cord injury. This article reviews the effects of curcumin on the repair of nerve injury, with emphasis on the various mechanisms by which curcumin promotes the treatment of spinal cord injury.

Coupling of autophagy and the mitochondrial intrinsic apoptosis pathway modulates proteostasis and ageing in Caenorhabditis elegans

Mitochondria preserve metabolic homeostasis and integrate stress signals, to trigger cytoprotective, or cell death pathways. Mitochondrial homeostasis and function decline with age. The mechanisms underlying the deterioration of mitochondrial homeostasis during ageing, or in age-associated pathologies, remain unclear. Here, we show that CISD-1, a mitochondrial iron-sulfur cluster binding protein, implicated in the pathogenesis of Wolfram neurodegenerative syndrome type 2, modulates longevity in the nematode Caenorhabditis elegans by engaging autophagy and the mitochondrial intrinsic apoptosis pathway. The anti-apoptotic protein CED-9 is the downstream effector that mediates CISD-1-dependent effects on proteostasis, neuronal integrity and lifespan. Moreover, intracellular iron abundance is critical for CISD-1 function, since mild iron supplementation is sufficient to decelerate ageing and partly ameliorate the disturbed mitochondrial bioenergetics and proteostasis of CISD-1 deficient animals. Our findings reveal that CISD-1 serves as a mechanistic link between autophagy and the apoptotic pathway in mitochondria to differentially modulate organismal proteostasis and ageing, and suggest novel approaches which could facilitate the treatment of Wolfram Syndrome or related diseases.

Advances in Human Mitochondria-Based Therapies

Mitochondria are the key biological generators of eukaryotic cells, controlling the energy supply while providing many important biosynthetic intermediates. Mitochondria act as a dynamic, functionally and structurally interconnected network hub closely integrated with other cellular compartments via biomembrane systems, transmitting biological information by shuttling between cells and tissues. Defects and dysregulation of mitochondrial functions are critically involved in pathological mechanisms contributing to aging, cancer, inflammation, neurodegenerative diseases, and other severe human diseases. Mediating and rejuvenating the mitochondria may therefore be of significant benefit to prevent, reverse, and even treat such pathological conditions in patients. The goal of this review is to present the most advanced strategies using mitochondria to manage such disorders and to further explore innovative approaches in the field of human mitochondria-based therapies.

Hesperetin promotes longevity and delays aging via activation of Cisd2 in naturally aged mice

Background

The human CISD2 gene is located within a longevity region mapped on chromosome 4q. In mice, Cisd2 levels decrease during natural aging and genetic studies have shown that a high level of Cisd2 prolongs mouse lifespan and healthspan. Here, we evaluate the feasibility of using a Cisd2 activator as an effective way of delaying aging.

Methods

Hesperetin was identified as a promising Cisd2 activator by herb compound library screening. Hesperetin has no detectable toxicity based on in vitro and in vivo models. Naturally aged mice fed dietary hesperetin were used to investigate the effect of this Cisd2 activator on lifespan prolongation and the amelioration of age-related structural defects and functional decline. Tissue-specific Cisd2 knockout mice were used to study the Cisd2-dependent anti-aging effects of hesperetin. RNA sequencing was used to explore the biological effects of hesperetin on aging.

Results

Three discoveries are pinpointed. Firstly, hesperetin, a promising Cisd2 activator, when orally administered late in life, enhances Cisd2 expression and prolongs healthspan in old mice. Secondly, hesperetin functions mainly in a Cisd2-dependent manner to ameliorate age-related metabolic decline, body composition changes, glucose dysregulation, and organ senescence. Finally, a youthful transcriptome pattern is regained after hesperetin treatment during old age.

Conclusions

Our findings indicate that a Cisd2 activator, hesperetin, represents a promising and broadly effective translational approach to slowing down aging and promoting longevity via the activation of Cisd2.

Targeting autophagy in pancreatic cancer: The cancer stem cell perspective

Pancreatic cancer is currently the seventh leading cause of cancer-related deaths worldwide, with the estimated death toll approaching half a million annually. Pancreatic ductal adenocarcinoma (PDAC) is the most common (>90% of cases) and most aggressive form of pancreatic cancer, with extremely poor prognosis and very low survival rates. PDAC is initiated by genetic alterations, usually in the oncogene KRAS and tumor suppressors CDKN2A, TP53 and SMAD4, which in turn affect a number of downstream signaling pathways that regulate important cellular processes. One of the processes critically altered is autophagy, the mechanism by which cells clear away and recycle impaired or dysfunctional organelles, protein aggregates and other unwanted components, in order to achieve homeostasis. Autophagy plays conflicting roles in PDAC and has been shown to act both as a positive effector, promoting the survival of pancreatic tumor-initiating cells, and as a negative effector, increasing cytotoxicity in uncontrollably expanding cells. Recent findings have highlighted the importance of cancer stem cells in PDAC initiation, progression and metastasis. Pancreatic cancer stem cells (PaCSCs) comprise a small subpopulation of the pancreatic tumor, characterized by cellular plasticity and the ability to self-renew, and autophagy has been recognised as a key process in PaCSC maintenance and function, simultaneously suggesting new strategies to achieve their selective elimination. In this review we evaluate recent literature that links autophagy with PaCSCs and PDAC, focusing our discussion on the therapeutic implications of pharmacologically targeting autophagy in PaCSCs, as a means to treat PDAC.

Rejuvenation: Turning Back Time by Enhancing CISD2

The aging human population with age-associated diseases has become a problem worldwide. By 2050, the global population of those who are aged 65 years and older will have tripled. In this context, delaying age-associated diseases and increasing the healthy lifespan of the aged population has become an important issue for geriatric medicine. CDGSH iron-sulfur domain 2 (CISD2), the causative gene for Wolfram syndrome 2 (WFS2; MIM 604928), plays a pivotal role in mediating lifespan and healthspan by maintaining mitochondrial function, endoplasmic reticulum integrity, intracellular Ca²⁺ homeostasis, and redox status. Here, we summarize the most up-to-date publications on CISD2 and discuss the crucial role that this gene plays in aging and age-associated diseases. This review mainly focuses on the following topics: (1) CISD2 is one of the few pro-longevity genes identified in mammals. Genetic evidence from loss-of-function (knockout mice) and gain-of-function (transgenic mice) studies have demonstrated that CISD2 is essential to lifespan control. (2) CISD2 alleviates age-associated disorders. A higher level of CISD2 during natural aging, when achieved by transgenic overexpression, improves Alzheimer's disease, ameliorates non-alcoholic fatty liver disease and steatohepatitis, and maintains corneal epithelial homeostasis. (3) CISD2, the expression of which otherwise decreases during natural aging, can be pharmaceutically activated at a late-life stage of aged mice. As a proof-of-concept, we have provided evidence that hesperetin is a promising CISD2 activator that is able to enhance CISD2 expression, thus slowing down aging and promoting longevity. (4) The anti-aging effect of hesperetin is mainly dependent on CISD2 because transcriptomic analysis of the skeletal muscle reveals that most of the differentially expressed genes linked to hesperetin are regulated by hesperetin in a CISD2-dependent manner. Furthermore, three major metabolic pathways that are affected by hesperetin have been identified in skeletal muscle, namely lipid metabolism, protein homeostasis, and nitrogen and amino acid metabolism. This review highlights the urgent need for CISD2-based pharmaceutical development to be used as a potential therapeutic strategy for aging and age-associated diseases.

CDGSH iron sulfur domain 2 mitigates apoptosis, oxidative stress and inflammatory response caused by oxygen-glucose deprivation/reoxygenation in HT22 hippocampal neurons by Akt-Nrf2-activated pathway

CDGSH iron sulfur domain 2 (Cisd2) is known as a key determinant factor in maintaining cellular homeostasis. However, whether Cisd2 contributes to the mediation of neuronal injury during ischemic stroke has not been well stressed. This work focuses on investigating the role of Cisd2 in regulating neuronal injury caused by oxygen-glucose deprivation/reoxygenation (OGD/R). The dramatic down-regulation of Cisd2 was observed in hippocampal neurons suffering from OGD/R injury. In Cisd2-overexpressed neurons, OGD/R-induced neuronal apoptosis, oxidative stress and inflammation were prominently mitigated. Further investigation uncovered that the forced expression of Cisd2 reinforced the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in OGD/R-exposed neurons. Moreover, the overexpression of Cisd2 enhanced Akt activation, and the restraint of Akt abolished Cisd2-induced Nrf2 activation. Importantly, restraint of Nrf2 reversed Cisd2-conferred neuroprotective effects in OGD/R-exposed neurons. Taken together, our findings indicate that Cisd2 is able to protect neurons from OGD/R-induced injuries by strengthening Nrf2 activation via Akt. Our work identifies Cisd2 as a potential determinant factor for neuronal injury during cerebral ischemia/reperfusion injury.

Inhibition of CISD2 promotes ferroptosis through ferritinophagy-mediated ferritin turnover and regulation of p62-Keap1-NRF2 pathway

BACKGROUND

CDGSH iron sulfur domain 2 (CISD2) is an iron-sulfur protein with a [2Fe-2S] cluster, which is critical for cell proliferation and iron homeostasis. It has been demonstrated that aberrant expression of CISD2 is associated with the progression of multiple cancers. However, the underlying mechanism of CISD2 in regulating tumorigenesis remains obscure.

METHODS

Bioinformatics strategies were used to investigate the protein interaction network and functional annotation of CISD2. In the functional experiment, cell viability was measured by CCK-8 kit. The levels of cellular reactive oxygen species (ROS), intracellular free iron, lipid peroxides, and lysosomal activity were determined by DCF-DA, RPA, C11-BODIPY, and cathepsin B staining, respectively. The glutathione (GSH) content was determined using a GSH assay kit.

RESULTS

We showed that knockdown of CISD2 significantly accelerated the Erastin-induced ferroptotic cell death with excess lipid peroxidation, GSH exhaustion, and iron accumulation, while overexpression of CISD2 hindered the sensitivity to Erastin. Further assays via confocal microscopy and western blot exhibited that CISD2 knockdown markedly enhanced the lysosomal activity, and activated ferritinophagy under the exposure of Erastin. Pharmacological inhibition of lysosomal function could inhibit the degradation of ferritin heavy chain (FTH), and attenuate the phenotypes of ferroptosis, such as accelerated iron accumulation and lipid peroxidation. Notably, we found that Erastin-induced compensatory elevation of nuclear factor erythroid 2-related factor 2 (NRF2) could be eliminated in CISD2 depletion cells. Mechanically, CISD2 knockdown promoted the degradation of autophagy adaptor p62 and resulted in an increased binding affinity of Keap1 with NRF2, thus leading to the increased ubiquitination and subsequent degradation of NRF2. Enforced expression of NRF2 reversed the sensitivity of shCISD2 cells to ferroptosis both in vitro and in vivo. Conversely, enforced expression of Keap1 exacerbated the degradation of NRF2, reduced the transcriptional expression of FTH and heme oxygenase 1 (HO-1), increased the oxidative damage, and thus further facilitated ferroptosis.

CONCLUSION

Taken together, our current results illustrated two parallel mechanisms involved in the shCISD2-mediated ferroptosis. One was that shCISD2 enhanced the accumulation of free iron via ferritinophagy-dependent ferritin turnover; the other was that CISD2 depletion induced the inhibition of the p62-Keap1-NRF2 pathway, which resulted in oxidative stress and ferroptosis.

Disruption of mitochondria-associated ER membranes impairs insulin sensitivity and thermogenic function of adipocytes

The prevalence and healthcare burden of obesity and its related metabolic disorders such as type 2 diabetes (T2D) are increasing rapidly. A better understanding of the pathogenesis of these diseases helps to find the therapeutic strategies. Mitochondria and endoplasmic reticulum (ER) are two important organelles involved in the maintenance of intracellular Ca²⁺ and ROS homeostasis. Their functional defects are thought to participate in the pathogenesis of insulin resistance or T2D. The proper structure and function of the mitochondria-associated ER membranes (MAMs) is required for efficient communication between the ER and mitochondria and defects in MAMs have been shown to play a role in metabolic syndrome and other diseases. However, the detailed mechanism to link MAMs dysfunction and pathogenesis of insulin resistance or T2D remains unclear. In the present study, we demonstrated that the proteins involved in .MAMs structure are upregulated and the formation of MAMs is increased during adipogenic differentiation of 3T3-L1 preadipocytes. Disruption of MAMs by knocking down GRP75, which is responsible for connecting ER and mitochondria, led to the impairment of differentiation and ROS accumulation in 3T3-L1 preadipocytes. Most importantly, the differentiated 3T3-L1 adipocytes with GRP75 knockdown displayed inactivation of insulin signaling pathway upon insulin stimulation. Moreover, GRP75 knockdown impaired thermogenesis and glucose utilization in brown adipocytes, the adipocytes with abundant mitochondria that regulate whole-body energy homeostasis. Taken together, our findings suggest that MAMs formation is essential for promoting mitochondrial function and maintaining a proper redox status to enable the differentiation of preadipocytes and normal functioning such as insulin signaling and thermogenesis in mature adipocytes.

Diabetes Out-of-the-Box: Diabetes Mellitus and Impairment in Hearing and Vision

PURPOSEOF REVIEW

This review aims to provide an update on the etiologies of diabetes that are due to genetic disorders and that co-occur with impaired hearing or vision and to compare them. The potential mechanisms, including novel treatments, will be detailed.

RECENT FINDINGS

Wolfram syndrome, Kearns-Sayre syndrome, thiamine-responsive megaloblastic anemia, and maternally inherited diabetes and deafness are genetic disorders characterized by diabetes, impaired hearing, and vision. They differ in mode of inheritance, age at presentation, and the involvement of other organs; they are often misdiagnosed as type 1 or type 2 diabetes. Suspicion of a genetic diabetes syndrome should be raised when pancreatic autoantibodies are negative, other organs are involved, and family history includes diabetes. Correct diagnosis of the various syndromes is important for tailoring the most advanced treatment, preventing disease progression, and enabling proper genetic counseling.

Wolframin deficiency is accompanied with metabolic inflexibility in rat striated muscles

The protein wolframin is localized in the membrane of the endoplasmic reticulum (ER), influencing Ca2+ metabolism and ER interaction with mitochondria, but the exact role of the protein remains unclear. Mutations in Wfs1 gene cause autosomal recessive disorder Wolfram syndrome (WS). The first symptom of the WS is diabetes mellitus, so accurate diagnosis of the disease as WS is often delayed. In this study we aimed to characterize the role of the Wfs1 deficiency on bioenergetics of muscles. Alterations in the bioenergetic profiles of Wfs1-exon-5-knock-out (Wfs1KO) male rats in comparison with their wild-type male littermates were investigated using high-resolution respirometry, and enzyme activity measurements. The changes were followed in oxidative (cardiac and soleus) and glycolytic (rectus femoris and gastrocnemius) muscles. There were substrate-dependent alterations in the oxygen consumption rate in Wfs1KO rat muscles. In soleus muscle, decrease in respiration rate was significant in all the followed pathways. The relatively small alterations in muscle during development of WS, such as increased mitochondrial content and/or increase in the OxPhos-related enzymatic activity could be an adaptive response to changes in the metabolic environment. The significant decrease in the OxPhos capacity is substrate dependent indicating metabolic inflexibility when multiple substrates are available.

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Wolfram syndrome (WS) model rats have muscle type-dependent metabolic changes.

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Substrate-dependent modulation of OxPhos in WS model rat muscles.

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Metabolic inflexibility in early-stage WS rat muscle mitochondria.

Dysregulated Ca2+ Homeostasis as a Central Theme in Neurodegeneration: Lessons from Alzheimer's Disease and Wolfram Syndrome

Calcium ions (Ca²⁺) operate as important messengers in the cell, indispensable for signaling the underlying numerous cellular processes in all of the cell types in the human body. In neurons, Ca²⁺ signaling is crucial for regulating synaptic transmission and for the processes of learning and memory formation. Hence, the dysregulation of intracellular Ca²⁺ homeostasis results in a broad range of disorders, including cancer and neurodegeneration. A major source for intracellular Ca²⁺ is the endoplasmic reticulum (ER), which has close contacts with other organelles, including mitochondria. In this review, we focus on the emerging role of Ca²⁺ signaling at the ER–mitochondrial interface in two different neurodegenerative diseases, namely Alzheimer’s disease and Wolfram syndrome. Both of these diseases share some common hallmarks in the early stages, including alterations in the ER and mitochondrial Ca²⁺ handling, mitochondrial dysfunction and increased Reactive oxygen species (ROS) production. This indicates that similar mechanisms may underly these two disease pathologies and suggests that both research topics might benefit from complementary research.

A peptide-derived strategy for specifically targeting the mitochondria and ER of cancer cells: a new approach in fighting cancer

An effective anti-cancer therapy should exclusively target cancer cells and trigger in them a broad spectrum of cell death pathways that will prevent avoidance. Here, we present a new approach in cancer therapy that specifically targets the mitochondria and ER of cancer cells. We developed a peptide derived from the flexible and transmembrane domains of the human protein NAF-1/CISD2. This peptide (NAF-144-67) specifically permeates through the plasma membranes of human epithelial breast cancer cells, abolishes their mitochondria and ER, and triggers cell death with characteristics of apoptosis, ferroptosis and necroptosis. In vivo analysis revealed that the peptide significantly decreases tumor growth in mice carrying xenograft human tumors. Computational simulations of cancer vs. normal cell membranes reveal that the specificity of the peptide to cancer cells is due to its selective recognition of their membrane composition. NAF-144-67 represents a promising anti-cancer lead compound that acts via a unique mechanism.

Anti-Inflammatory CDGSH Iron-Sulfur Domain 2: A Biomarker of Central Nervous System Insult in Cellular, Animal Models and Patients

Spinal cord injury (SCI) promotes brain inflammation; conversely, brain injury promotes spinal neuron loss. There is a need to identify molecular biomarkers and therapeutic targets for central nervous system (CNS) injury. CDGSH iron-sulfur structural domain 2 (CISD2), an NF-κB antagonist, is downregulated after injury in vivo and in vitro. We aimed to examine the diagnostic value of CISD2 in patients with CNS insult. Plasma and cerebrospinal fluid (CSF) CISD2 levels were decreased in 13 patients with CNS insult and were negatively correlated with plasma IL6 levels (associated with disease severity; r = −0.7062; p < 0.01). SCI-induced inflammatory mediators delivered through CSF promoted mouse brain inflammation at 1 h post-SCI. Anti-CISD2 antibody treatment exacerbated SCI-induced inflammation in mouse spine and brain. Lipopolysaccharide-stimulated siCISD2-transfected EOC microglial cells exhibited proinflammatory phenotypes (enhanced M1 polarization, decreased M2 polarization, and increased intranuclear NF-κB p65 translocation). Plasma and CSF CISD2 levels were increased in three patients with CNS insult post-therapeutic hypothermia. CISD2 levels were negatively correlated with plasma and CSF levels of inflammatory mediators. CISD2 inhibition and potentiation experiments in cells, animals, and humans revealed CISD2 as a biomarker for CNS insult and upregulation of CISD2 anti-inflammatory properties as a potential therapeutic strategy for CNS insult.

The application of precision medicine in monogenic diabetes

INTRODUCTION

Monogenic diabetes, a form of diabetes mellitus, is caused by a mutation in a single gene and may account for 1-2% of all clinical forms of diabetes. To date, more than 40 loci have been associated with either isolated or syndromic monogenic diabetes.

AREAS COVERED

While the request of a genetic test is mandatory for cases with diabetes onset in the first 6 months of life, a decision may be difficult for childhood or adolescent diabetes. In an effort to assist the clinician in this task, we have grouped monogenic diabetes genes according to the age of onset (or incidental discovery) of hyperglycemia and described the additional clinical features found in syndromic diabetes. The therapeutic options available are reviewed.

EXPERT OPINION

Technical improvements in DNA sequencing allow for rapid, simultaneous analysis of all genes involved in monogenic diabetes, progressively shrinking the area of unsolved cases. However, the complexity of the analysis of genetic data requires close cooperation between the geneticist and the diabetologist, who should play a proactive role by providing a detailed clinical phenotype that might match a specific disease gene.

The [2Fe-2S] protein CISD2 plays a key role in preventing iron accumulation in cardiomyocytes

Considered a key aging gene, CISD2, encoding CDGSH iron-sulfur domain-containing protein 2, plays a central role in regulating calcium homeostasis, preventing mitochondrial dysfunction, and the activation of autophagy and apoptosis in different cells. Here, we show that cardiomyocytes from CISD2-null mice accumulate high levels of iron and contain high levels of transferrin receptor and ferritin. Using proteomics and transmission electron microscopy, we further show that the lack of CISD2 induces several features of the aging process in young mice, but other features are not induced. Taken together, our findings suggest that CISD2 protects cardiomyocytes from overaccumulation of iron, which is common in aging hearts and can contribute to the pathogenesis of heart failure.

Clinical Peculiarities in a Cohort of Patients with Wolfram Syndrome 1

Wolfram syndrome 1 is a rare, autosomal recessive, neurodegenerative, progressive disorder. Insulin-dependent, non-autoimmune diabetes mellitus and bilateral progressive optic atrophy are both sensitive and specific criteria for clinical diagnosis. The leading cause of death is central respiratory failure resulting from brainstem atrophy. We describe the clinical features of fourteen patients from seven different families followed in our Diabetes Center. The mean age at Wolfram syndrome 1 diagnosis was 12.4 years. Diabetes mellitus was the first clinical manifestation, in all patients. Sensorineural hearing impairment and central diabetes insipidus were present in 85.7% of patients. Other endocrine findings included hypogonadotropic hypogonadism (7.1%), hypergonadotropic hypogonadism (7.1%), and Hashimoto’s thyroiditis (21.4%). Neuropsychiatric disorders were detected in 35.7% of patients, and urogenital tract abnormalities were present in 21.4%. Finally, heart diseases were found in 14.2% of patients. Eight patients (57.1%) died at the mean age of 27.3 years. The most common cause of death was respiratory failure which occurred in six patients. The remaining two died due to end-stage renal failure and myocardial infarction. Our data are superimposable with those reported in the literature in terms of mean age of onset, the clinical course of the disease, and causes of death. The frequency of deafness and diabetes insipidus was higher in our patients. The incidence of urogenital diseases was lower although it led to the death of one patient. Long-term follow-up studies including large patient cohorts are necessary to establish potential genotype-phenotype correlation in order to personalize the most suitable clinical approach for each patient.

Cisd2 slows down liver aging and attenuates age-related metabolic dysfunction in male mice

The liver plays a pivotal role in mammalian aging. However, the mechanisms underlying liver aging remain unclear. Cisd2 is a pro‐longevity gene in mice. Cisd2 mediates lifespan and healthspan via regulation of calcium homeostasis and mitochondrial functioning. Intriguingly, the protein level of Cisd2 is significantly decreased by about 50% in the livers of old male mice. This down‐regulation of Cisd2 may result in the aging liver exhibiting non‐alcoholic fatty liver disease (NAFLD) phenotype. Here, we use Cisd2 transgenic mice to investigate whether maintaining Cisd2 protein at a persistently high level is able to slow down liver aging. Our study identifies four major discoveries. Firstly, that Cisd2 expression attenuates age‐related dysregulation of lipid metabolism and other pathological abnormalities. Secondly, revealed by RNA sequencing analysis, the livers of old male mice undergo extensive transcriptomic alterations, and these are associated with steatosis, hepatitis, fibrosis, and xenobiotic detoxification. Intriguingly, a youthful transcriptomic profile, like that of young 3‐month‐old mice, was found in old Cisd2 transgenic male mice at 26 months old. Thirdly, Cisd2 suppresses the age‐associated dysregulation of various transcription regulators (Nrf2, IL‐6, and Hnf4a), which keeps the transcriptional network in a normal pattern. Finally, a high level of Cisd2 protein protects the liver from oxidative stress, and this is associated with a reduction in mitochondrial DNA deletions. These findings demonstrate that Cisd2 is a promising target for the development of therapeutic agents that, by bringing about an effective enhancement of Cisd2 expression, will slow down liver aging.

Cellular senescence links mitochondria-ER contacts and aging

Membrane contact sites emerged in the last decade as key players in the integration, regulation and transmission of many signals within cells, with critical impact in multiple pathophysiological contexts. Numerous studies accordingly point to a role for mitochondria-endoplasmic reticulum contacts (MERCs) in modulating aging. Nonetheless, the driving cellular mechanisms behind this role remain unclear. Recent evidence unravelled that MERCs regulate cellular senescence, a state of permanent proliferation arrest associated with a pro-inflammatory secretome, which could mediate MERC impact on aging. Here we discuss this idea in light of recent advances supporting an interplay between MERCs, cellular senescence and aging.

Iron Deficiency Caused by Intestinal Iron Loss-Novel Candidate Genes for Severe Anemia

The adult human body contains about 4 g of iron. About 1-2 mg of iron is absorbed every day, and in healthy individuals, the same amount is excreted. We describe a patient who presents with severe iron deficiency anemia with hemoglobin levels below 6 g/dL and ferritin levels below 30 ng/mL. Although red blood cell concentrates and intravenous iron have been substituted every month for years, body iron stores remain depleted. Diagnostics have included several esophago-gastro-duodenoscopies, colonoscopies, MRI of the liver, repetitive bone marrow biopsies, psychological analysis, application of radioactive iron to determine intact erythropoiesis, and measurement of iron excretion in urine and feces. Typically, gastrointestinal bleeding is a major cause of iron loss. Surprisingly, intestinal iron excretion in stool in the patient was repetitively increased, without gastrointestinal bleeding. Furthermore, whole exome sequencing was performed in the patient and additional family members to identify potential causative genetic variants that may cause intestinal iron loss. Under different inheritance models, several rare mutations were identified, two of which (in CISD1 and KRI1) are likely to be functionally relevant. Intestinal iron loss in the current form has not yet been described and is, with high probability, the cause of the severe iron deficiency anemia in this patient.

Disrupting CISD2 function in cancer cells primarily impacts mitochondrial labile iron levels and triggers TXNIP expression

The CISD2 (NAF-1) protein plays a key role in regulating cellular homeostasis, aging, cancer and neurodegenerative diseases. It was found to control different calcium, reactive oxygen species (ROS), and iron signaling mechanisms. However, since most studies of CISD2 to date were conducted with cells that constitutively lack, overexpress, or contain mutations in CISD2, the relationships between these different signaling processes are unclear. To address the hierarchy of signaling events occurring in cells upon CISD2 disruption, we developed an inducible system to express CISD2, or the dominant-negative H114C inhibitor of CISD2, in human breast cancer cells. Here, we report that inducible disruption of CISD2 function causes an immediate disruption in mitochondrial labile iron (mLI), and that this disruption results in enhanced mitochondrial ROS (mROS) levels. We further show that alterations in cytosolic and ER calcium levels occur only after the changes in mLI and mROS levels happen and are unrelated to them. Interestingly, disrupting CISD2 function resulted in the enhanced expression of the tumor suppressor thioredoxin-interacting protein (TXNIP) that was dependent on the accumulation of mLI and associated with ferroptosis activation. CISD2 could therefore regulate the expression of TXNIP in cancer cells, and this regulation is dependent on alterations in mLI levels.

Hallmarks of Testicular Aging: The Challenge of Anti-Inflammatory and Antioxidant Therapies Using Natural and/or Pharmacological Compounds to Improve the Physiopathological Status of the Aged Male Gonad

The evolutionary theory of aging supports a trade-off relationship between reproduction and aging. Aging of the male reproductive system primarily affects the testes, leading to a decrease in the levels of sexual hormones, alterations in sperm quality and production, and a decline in fertility that does not necessarily involve a complete cessation of spermatogenesis. Inflammation, oxidation, and apoptosis are events considered as predictors of pathogenesis and the development of age-related diseases that are frequently observed in aged testes. Although the molecular mechanisms are still poorly understood, accumulating evidence points toward pro-inflammatory molecules and reactive oxygen species as primary contributing factors for testicular aging. However, the real impact of aging-related testicular alterations on fertility, reproductive health, and life span is far from being fully revealed. This work discusses the current knowledge on the impact of aging in the testis, particularly of aging-related dysregulated inflammation and oxidative damage on the functioning of its different cell populations. More interestingly, this review covers the potential benefits of anti-aging interventions and therapies using either pharmacological compounds (such as non-selective non-steroidal anti-inflammatory medication) or more natural alternatives (such as various nutraceuticals or even probiotics) that exhibit anti-inflammatory, antioxidant, and anti-apoptotic properties. Some of these are currently being investigated or are already in clinical use to delay or prevent testicular aging.

Cisd2 plays an essential role in corneal epithelial regeneration

Background

Age-related changes affecting the ocular surface cause vision loss in the elderly. Cisd2 deficiency drives premature aging in mice as well as resulting in various ocular surface abnormalities. Here we investigate the role of CISD2 in corneal health and disease.

Methods

We studied the molecular mechanism underlying the ocular phenotypes brought about by Cisd2 deficiency using both Cisd2 knockout (KO) mice and a human corneal epithelial cell (HCEC) cell line carrying a CRISPR-mediated CISD2KO background. We also develop a potential therapeutic strategy that targets the Ca²⁺ signaling pathway, which has been found to be dysregulated in the corneal epithelium of subjects with ocular surface disease in order to extend the mechanistic findings into a translational application.

Findings

Firstly, in patients with corneal epithelial disease, CISD2 is down-regulated in their corneal epithelial cells. Secondly, using mouse cornea, Cisd2 deficiency causes a cycle of chronic injury and persistent repair resulting in exhaustion of the limbal progenitor cells. Thirdly, in human corneal epithelial cells, CISD2 deficiency disrupts intracellular Ca²⁺ homeostasis, impairing mitochondrial function, thereby retarding corneal repair. Fourthly, cyclosporine A and EDTA facilitate corneal epithelial wound healing in Cisd2 knockout mice. Finally, cyclosporine A treatment restores corneal epithelial erosion in patients with dry eye disease, which affects the ocular surface.

Interpretation

These findings reveal that Cisd2 plays an essential role in the cornea and that Ca²⁺ signaling pathways are potential targets for developing therapeutics of corneal epithelial diseases.

Funding

This study was supported by the Ministry of Science and Technology (MOST) and Chang Gung Medical Research Foundation, Taiwan.

Rejuvenating the Aging Heart by Enhancing the Expression of the Cisd2 Prolongevity Gene

Aging is the major risk factor for cardiovascular disease, which is the leading cause of mortality worldwide among aging populations. Cisd2 is a prolongevity gene that mediates lifespan in mammals. Previously, our investigations revealed that a persistently high level of Cisd2 expression in mice is able to prevent age-associated cardiac dysfunction. This study was designed to apply a genetic approach that induces cardiac-specific Cisd2 overexpression (Cisd2 icOE) at a late-life stage, namely a time point immediately preceding the onset of old age, and evaluate the translational potential of this approach. Several discoveries are pinpointed. Firstly, Cisd2 is downregulated in the aging heart. This decrease in Cisd2 leads to cardiac dysfunction and impairs electromechanical performance. Intriguingly, Cisd2 icOE prevents an exacerbation of age-associated electromechanical dysfunction. Secondly, Cisd2 icOE ameliorates cardiac fibrosis and improves the integrity of the intercalated discs, thereby reversing various structural abnormalities. Finally, Cisd2 icOE reverses the transcriptomic profile of the aging heart, changing it from an older-age pattern to a younger pattern. Intriguingly, Cisd2 icOE modulates a number of aging-related pathways, namely the sirtuin signaling, autophagy, and senescence pathways, to bring about rejuvenation of the heart as it enters old age. Our findings highlight Cisd2 as a novel molecular target for developing therapies targeting cardiac aging.

Intracellular targeting of Cisd2/Miner1 to the endoplasmic reticulum

Background

Cisd1 and Cisd2 proteins share very similar structures with an N-terminal membrane-anchoring domain and a C-terminal cytosolic domain containing an iron-cluster binding domain and ending with a C-terminal KKxx sequence. Despite sharing a similar structure, Cisd1 and Cisd2 are anchored to different compartments: mitochondria for Cisd1 and endoplasmic reticulum for Cisd2. The aim of this study was to identify the protein motifs targeting Cisd2 to the ER and ensuring its retention in this compartment.

Results

We used new recombinant antibodies to localize Cisd1 and Cisd2 proteins, as well as various protein chimeras. Cisd2 is targeted to the ER by its N-terminal sequence. It is then retained in the ER by the combined action of a C-terminal COPI-binding KKxx ER retrieval motif, and of an ER-targeting transmembrane domain. As previously reported for Cisd1, Cisd2 can alter the morphology of the compartment in which it accumulates.

Conclusion

Although they share a very similar structure, Cisd1 and Cisd2 use largely different intracellular targeting motifs to reach their target compartment (mitochondria and endoplasmic reticulum, respectively).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12860-021-00387-1.

Uniting the divergent Wolfram syndrome-linked proteins WFS1 and CISD2 as modulators of Ca2+ signaling

[Figure: see text].

Cisd2 Preserves the Youthful Pattern of the Liver Proteome during Natural Aging of Mice

Cisd2 (CDGSH iron sulfur domain 2) is a pro-longevity gene that extends the lifespan and health span of mice, ameliorates age-associated structural damage and limits functional decline in multiple tissues. Non-alcoholic fatty liver disease (NAFLD), which plays an important role in age-related liver disorders, is the most common liver disease worldwide. However, no medicines that can be used to specifically and effectively treat NAFLD are currently approved for this disease. Our aim was to provide pathological and molecular evidence to show that Cisd2 protects the liver from age-related dysregulation of lipid metabolism and protein homeostasis. This study makes four major discoveries. Firstly, a persistently high level of Cisd2 protects the liver from age-related fat accumulation. Secondly, proteomics analysis revealed that Cisd2 ameliorates age-related dysregulation of lipid metabolism, including lipid biosynthesis and β-oxidation, in mitochondria and peroxisomes. Thirdly, Cisd2 attenuates aging-associated oxidative modifications of proteins. Finally, Cisd2 regulates intracellular protein homeostasis by maintaining the functionality of molecular chaperones and protein synthesis machinery. Our proteomics findings highlight Cisd2 as a novel molecular target for the development of therapies targeting fatty liver diseases, and these new therapies are likely to help prevent subsequent malignant progression to cirrhosis and hepatocellular carcinoma.

CISD2 Promotes Resistance to Sorafenib-Induced Ferroptosis by Regulating Autophagy in Hepatocellular Carcinoma

Purpose

Sorafenib is a multi-kinase inhibitor that is used as a standard treatment for advanced hepatocellular carcinoma (HCC). However, the mechanism of sorafenib resistance in HCC is still unclear. It has been shown that CISD2 expression is related to the progression and poor prognosis of HCC. Here, we show a new role for CISD2 in sorafenib resistance in HCC.

Methods

Bioinformatic analysis was used to detect the expression of negative regulatory genes of ferroptosis in sorafenib-resistant samples. The concentration gradient method was used to establish sorafenib-resistant HCC cells. Western blot was used to detect the protein expression of CISD2, LC3, ERK, PI3K, AKT, mTOR, and Beclin1 in HCC samples. Quantitative real-time PCR (qPCR) was used to detect gene expression. CISD2 shRNA and Beclin1 shRNA were transfected to knock down the expression of the corresponding genes. Cell viability was detected by a CCK-8 assay. ROS were detected by DCFH-DA staining, and MDA and GSH were detected with a Lipid Peroxidation MDA Assay Kit and Micro Reduced Glutathione (GSH) Assay Kit, respectively. Flow cytometry was used to detect apoptosis and the levels of ROS and iron ions.

Results

CISD2 was highly expressed in HCC cells compared with normal cells and was associated with poor prognosis in patients. Knockdown of CISD2 promoted a decrease in the viability of drug-resistant HCC cells. CISD2 knockdown promoted sorafenib-induced ferroptosis in resistant HCC cells. The levels of ROS, MDA, and iron ions increased, but the change in GSH was not obvious. Knockdown of CISD2 promoted uncontrolled autophagy in resistant HCC cells. Inhibition of autophagy attenuated CISD2 knockdown-induced ferroptosis. The autophagy promoted by CISD2 knockdown was related to Beclin1. When CISD2 and Beclin1 were inhibited, the effect on ferroptosis was correspondingly weakened.

Conclusion

Inhibition of CISD2 promoted sorafenib-induced ferroptosis in resistant cells, and this process promoted excessive iron ion accumulation through autophagy, leading to ferroptosis. The combination of CISD2 inhibition and sorafenib treatment is an effective therapeutic strategy for resistant HCC.