Production of active human iduronate-2-sulfatase (IDS) enzyme in Nicotiana benthamiana.

Many strategies have been developed to produce high levels of biologically active recombinant proteins in plants for biopharmaceutical purposes. However, the production of an active form of human iduronate-2-sulfatase (hIDS) for the treatment of Hunter syndrome by enzyme replacement therapy (ERT) is challenging due to the requirement for cotranslational modification by a formylglycine-producing enzyme encoded by sulfatase modifying factor 1 (hSUMF1) at the Cys84 residue, which converts it to C(alpha)-formylglycine. In this study, we have shown that hIDS can be highly expressed in N. benthamiana by using different constructs. Among them, BiP-GB1-L-dCBD1-2L-8xHis-L-6xHis-3L-EK-hIDS-HDEL (GB1-CBD1-hIDS) showed a high expression level when transiently co-expressed with the turnip crinkle virus gene silencing suppressor P38 and GB1-fused human calreticulin (GB1-CRT1) as a folding enhancer. The hSUMF1 was co-expressed with hIDS for cotranslational modification. The full-length recombinant proteins were purified using Ni2+-NTA affinity resin followed by enterokinase treatment to obtain tag-free hIDS. The N-terminal fragment was removed using microcrystalline cellulose (MCC) beads. The purified active form of hIDS can successfully cleave the sulfate group from an artificial substrate, 4-nitrocatechol sulfate, at a similar level to commercial hIDS expressed in animal cells. These results suggest that plants could be a promising platform for the production of recombinant hIDS.

Post-Transcriptional Induction of the Antiviral Host Factor GILT/IFI30 by Interferon Gamma.

Gamma-interferon-inducible lysosomal thiol reductase (GILT) plays pivotal roles in both adaptive and innate immunities. GILT exhibits constitutive expression within antigen-presenting cells, whereas in other cell types, its expression is induced by interferon gamma (IFN-γ). Gaining insights into the precise molecular mechanism governing the induction of GILT protein by IFN-γ is of paramount importance for adaptive and innate immunities. In this study, we found that the 5' segment of GILT mRNA inhibited GILT protein expression regardless of the presence of IFN-γ. Conversely, the 3' segment of GILT mRNA suppressed GILT protein expression in the absence of IFN-γ, but it loses this inhibitory effect in its presence. Although the mTOR inhibitor rapamycin suppressed the induction of GILT protein expression by IFN-γ, the expression from luciferase sequence containing the 3' segment of GILT mRNA was resistant to rapamycin in the presence of IFN-γ, but not in its absence. Collectively, this study elucidates the mechanism behind GILT induction by IFN-γ: in the absence of IFN-γ, GILT mRNA is constitutively transcribed, but the translation process is hindered by both the 5' and 3' segments. Upon exposure to IFN-γ, a translation inhibitor bound to the 3' segment is liberated, and a translation activator interacts with the 3' segment to trigger the initiation of GILT translation.

QSOX2 Deficiency-induced short stature, gastrointestinal dysmotility and immune dysfunction.

Postnatal growth failure is often attributed to dysregulated somatotropin action, however marked genetic and phenotypic heterogeneity exist. We report five patients from three families who present with short stature, immune dysfunction, atopic eczema and gastrointestinal pathology associated with recessive variants in QSOX2. QSOX2 encodes a nuclear membrane protein linked to disulphide isomerase and oxidoreductase activity. Loss of QSOX2 disrupts Growth hormone-mediated STAT5B nuclear translocation despite enhanced Growth hormone-induced STAT5B phosphorylation. Moreover, patient-derived dermal fibroblasts demonstrate Growth hormone-induced mitochondriopathy and reduced mitochondrial membrane potential. Located at the nuclear membrane, QSOX2 acts as a gatekeeper for regulating stabilisation and import of phosphorylated-STAT5B. Altogether, QSOX2 deficiency modulates human growth by impairing Growth hormone-STAT5B downstream activities and mitochondrial dynamics, which contribute to multi-system dysfunction. Furthermore, our work suggests that therapeutic recombinant insulin-like growth factor-1 may circumvent the Growth hormone-STAT5B dysregulation induced by pathological QSOX2 variants and potentially alleviate organ specific disease.

Sulfiredoxin-1 accelerates erastin-induced ferroptosis in HT-22 hippocampal neurons by driving heme Oxygenase-1 activation.

Ferroptosis, a recently identified non-apoptotic form of cell death, is strongly associated with neurological diseases and has emerged as a potential therapeutic target. Nevertheless, the fundamental mechanisms are still predominantly unidentified. In the current investigation, sulfiredoxin-1 (SRXN1) has been identified as a crucial regulator that enhances the susceptibility to ferroptosis in HT-22 mouse hippocampal cells treated with erastin. Utilizing TMT-based proteomics, a significant increase in SRXN1 expression was observed in erastin-exposed HT-22 cells. Efficient amelioration of erastin-induced ferroptosis was achieved via the knockdown of SRXN1, which resulted in the reduction of intracellular Fe2+ levels and reactive oxygen species (ROS) in HT-22 cells. Notably, the activation of Heme Oxygenase-1 (HO-1) was found to be crucial for inducing SRXN1 expression in HT-22 cells upon treatment with erastin. SRXN1 increased intracellular ROS and Fe2+ levels by activating HO-1 expression, which promoted erastin-induced ferroptosis in HT-22 cells. Inhibiting SRXN1 or HO-1 alleviated erastin-induced autophagy in HT-22 cells. Additionally, upregulation of SRXN1 or HO-1 increased the susceptibility of HT-22 cells to ferroptosis, a process that was counteracted by the autophagy inhibitor 3-Methyladenine (3-MA). These results indicate that SRXN1 is a key regulator of ferroptosis, activating the HO-1 protein through cellular redox regulation, ferrous iron accumulation, and autophagy in HT-22 cells. These findings elucidate a novel molecular mechanism of erastin-induced ferroptosis sensitivity and suggest that SRXN1-HO-1-autophagy-dependent ferroptosis serves as a promising treatment approach for neurodegenerative diseases.

Sulfiredoxin 1 ameliorates doxorubicin-induced cardiotoxicity by suppressing oxidative stress and inflammation via the Sirt1/NLRP3 pathway.

BACKGROUND: Doxorubicin (DOX) is limited in clinical use due to its cardiotoxic side effects. Oxidative stress and inflammation are pivotal mechanisms underlying doxorubicin-induced cardiotoxicity (DIC). Sulfiredoxin 1 (Srxn1) plays a central role in antioxidant effects. However, the role of Srxn1 in DIC has not yet been fully elucidated. This study aims to explore the effects and underlying mechanisms of Srxn1 on DIC. METHODS: We overexpressed Srxn1 in the myocardium using an adeno-associated virus 9 (AAV9) system, delivered through tail vein injection. C57BL/6 mice received intraperitoneal injections of DOX (4 mg/kg) weekly for four consecutive weeks to establish a mouse model of DIC. We used echocardiography, histopathological, and molecular techniques to elucidate the effects and mechanisms. RESULTS: Our findings demonstrate that overexpression of Srxn1 significantly enhanced cardiac function and mitigated myocardial injury in mice exposed to DOX. Overexpressing Srxn1 attenuated oxidative stress and inflammation induced by DOX. Furthermore, Srxn1 overexpression led to upregulation of sirtuin 1 (Sirt1) expression and inhibited the activation of the NOD-like receptor protein 3 (NLRP3) inflammasome. Notably, the protective effects of Srxn1 were significantly abrogated by the Sirt1 inhibitor EX527. CONCLUSION: The protective effects of Srxn1 against DOX-induced cardiac oxidative stress and inflammation operate by targeting the Sirt1/NLRP3 signaling pathway to alleviate DIC. Srxn1 could be a potential candidate for the treatment of DOX-induced myocardial injury.

Sulfiredoxin-1 promotes the growth of hepatocellular carcinoma by inhibiting TFEB-mediated autophagy and lysosome biogenesis.

Advanced hepatocellular carcinoma (HCC) patients have poor prognosis. As an endogenous antioxidant enzyme involved in a variety of bioprocesses, sulfiredoxin-1 (SRXN1) plays an irreplaceable role in promoting the development of tumors. However, the role and working mechanism of SRXN1 in HCC remain unclear. In this study, we confirmed that SRXN1 promoted the cell proliferation of HCC at genetic and pharmacological level, respectively. Transcriptome sequencing analysis revealed SRXN1 knockdown had a significant effect on the expression of lysosome biogenesis related genes. Further experiments validated that lysosome biogenesis and autophagic flux were enhanced after SRXN1 inhibition and reduced as SRXN1 overexpression. Mechanism study revealed that ROS accumulation induced TFEB nuclear translocation, followed by increased autophagy. Following this rationale, the combination of SRXN1 inhibitor and sorafenib demonstrated noticeable synergistic antitumor effect through the boost of ROS both in vivo and in vitro. Taken together, SRXN1 could be a potential therapeutic target for HCC therapy.

The impact of augmenter of liver regeneration in blunt liver trauma: An experimental model analysis.

BACKGROUND: Traumatic liver injury is an acute event that triggers liver repair. The augmenter of liver regeneration (ALR) has been identified as a growth factor involved in this process. This study evaluates the impact of ALR on isolated liver blunt trauma and examines its relationship with various time intervals. METHODS: Forty healthy female Wistar albino rats were divided into five groups (n=8 each). Isolated blunt liver trauma was induced using a custom-designed trauma platform in all groups except for Group 1. The groups were categorized by the timing of euthanasia post-trauma: 2nd (15 minutes), 3rd (30 minutes), 4th (45 minutes), and 5th (60 minutes). Assessments included plasma ALR levels, liver tissue ALR levels (both intact and lacerated), biochemical indices, and liver histological analysis. RESULTS: Plasma ALR levels in Group 4 were higher than in Groups 1 and 2 (p<0.01). Intact liver ALR levels in Groups 3 and 4 exceeded those in Group 1 (p<0.05, p<0.01, respectively). Intact liver tissue ALR levels in Group 5 were lower than in Groups 3 and 4 (p<0.05, p<0.01, respectively). Lacerated liver tissue ALR levels in Group 5 were higher than those in Groups 2 and 3. In Group 1, the plasma ALR level was higher than the intact liver tissue ALR level (p<0.05). In Group 2, plasma ALR levels exceeded those in intact liver tissue ALR levels (p<0.01). In Group 3, plasma ALR levels surpassed both lacerated and intact liver tissue ALR levels (p<0.05, p<0.001, respectively). In Group 4, the plasma ALR level was higher than the intact liver tissue ALR level (p<0.01), and the lacerated liver tissue level was higher than the intact liver ALR level (p<0.001). Additionally, inflammation scores were higher in Groups 3, 4, and 5 compared to Group 2 (p<0.05, p<0.01, p<0.01, respectively). CONCLUSION: This study is the first to explore the role of ALR in isolated blunt liver trauma. Following blunt liver trauma, both plasma and liver tissue ALR levels change within minutes.

Serum dithiothreitol-oxidizing capacity (DOC) is a promising biomarker for excluding significant liver fibrosis: a proof-of-concept study.

BACKGROUND: APRI and FIB-4 scores are used to exclude clinically significant fibrosis (defined as stage ≥ F2) in patients with chronic viral hepatitis. However, the cut-offs for these scores (generated by Youden indices) vary between different patient cohorts. This study aimed to evaluate whether serum dithiothreitol-oxidizing capacity (DOC), i.e., a surrogate test of quiescin sulfhydryl oxidase-1, which is a matrix remodeling enzyme, could be used to non-invasively identify significant fibrosis in patients with various chronic liver diseases (CLDs). METHODS: Diagnostic performance of DOC was compared with APRI and FIB-4 for identifying significant fibrosis. ROC curve analyses were undertaken in: a) two chronic hepatitis B (CHB) cohorts, independently established from hospitals in Wenzhou (n = 208) and Hefei (n = 120); b) a MASLD cohort from Wenzhou hospital (n = 122); and c) a cohort with multiple CLD etiologies (except CHB and MASLD; n = 102), which was identified from patients in both hospitals. Cut-offs were calculated using the Youden index. All CLD patients (n = 552) were then stratified by age for ROC curve analyses and cut-off calculations. RESULTS: Stratified by CLD etiology or age, ROC curve analyses consistently showed that the DOC test was superior to APRI and FIB-4 for discriminating between clinically significant fibrosis and no fibrosis, when APRI and FIB-4 showed poor/modest diagnostic performance (P < 0.05, P < 0.01 and P < 0.001 in 3, 1 and 3 cohort comparisons, respectively). Conversely, the DOC test was equivalent to APRI and FIB-4 when all tests showed moderate/adequate diagnostic performances (P > 0.05 in 11 cohort comparisons). DOC had a significant advantage over APRI or FIB-4 scores for establishing a uniform cut-off independently of age and CLD etiology (coefficients of variation of DOC, APRI and FIB-4 cut-offs were 1.7%, 22.9% and 47.6% in cohorts stratified by CLD etiology, 2.0%, 26.7% and 29.5% in cohorts stratified by age, respectively). The uniform cut-off was 2.13, yielded from all patients examined. Surprisingly, the uniform cut-off was the same as the DOC upper limit of normal with a specificity of 99%, estimated from 275 healthy control individuals. Hence, the uniform cut-off should possess a high negative predictive value for excluding significant fibrosis in primary care settings. A high DOC cut-off with 97.5% specificity could be used for detecting significant fibrosis (≥ F2) with an acceptable positive predictive value (87.1%). CONCLUSIONS: This proof-of-concept study suggests that the DOC test may efficiently rule out and rule in significant liver fibrosis, thereby reducing the numbers of unnecessary liver biopsies. Moreover, the DOC test may be helpful for clinicians to exclude significant liver fibrosis in the general population.

Non-syndromic retinal dystrophy associated with biallelic variation of SUMF1 and reduced leukocyte sulfatase activity.

Biallelic variants in SUMF1 are associated with multiple sulfatase deficiency (MSD), a rare lysosomal storage disorder typically diagnosed in early infancy or childhood, marked by severe neurodegeneration and early mortality. We present clinical and molecular characterisation of three unrelated patients aged 13 to 58 years with milder clinical manifestations due to SUMF1 disease variants, including two adult patients presenting with apparent non-syndromic retinal dystrophy. Whole genome sequencing identified biallelic SUMF1 variants in all three patients; Patient 1 homozygous for a complex allele c.[290G>T;293T>A]; p.[(Gly97Val);(Val98Glu)], Patient 2 homozygous for c.866A>G; p.(Tyr289Cys), and Patient 3 compound heterozygous for c.726-1G>C and p.(Tyr289Cys). Electroretinography indicated a rod-cone dystrophy with additional possible inner retinal dysfunction in all three patients. Biochemical studies confirmed reduced, but not absent, sulfatase enzyme activity in the absence of extra-ocular disease (Patient 1) or only mild systemic disease (Patients 2, 3). These cases are suggestive that non-null SUMF1 genotypes can cause an attenuated clinical phenotype, including retinal dystrophy without systemic complications, in adulthood.

Unraveling the role of sulfiredoxin-1 in early-onset preeclampsia: A key player in trophoblast ferroptosis.

Preeclampsia (PE) significantly contributes to obstetric complications and maternal mortality, yet its pathogenesis and mechanisms are not well understood. Sulfiredoxin-1 (SRXN1) is known for its antioxidant activity and its role in defending against oxidative stress; it is also linked to various cancers. However, the role of SRXN1 in PE remains unclear. Our study found a significant decrease in SRXN1 levels in the serum and placental tissues of patients with early-onset preeclampsia (EOPE). Similarly, a PE-like mouse model showed reduced SRXN1 expression. Our in vitro experiments showed that reducing SRXN1 impaired trophoblast viability, decreased invasion and migration, and led to cell death, primarily through ferroptosis. These results are consistent with analyses of placental tissues from EOPE patients. In summary, lower SRXN1 levels during pregnancy contribute to trophoblast ferroptosis, potentially affecting the development and progression of EOPE.

Augmenter of liver regeneration knockout aggravates tubular ferroptosis and macrophage activation by regulating carnitine palmitoyltransferase-1A-induced lipid metabolism in diabetic nephropathy.

AIM: Ferroptosis is a novel type of programmed cell death that performs a critical function in diabetic nephropathy (DN). Augmenter of liver regeneration (ALR) exists in the inner membrane of mitochondria, and inhibits inflammation, apoptosis, and oxidative stress in acute kidney injury; however, its role in DN remains unexplored. Here, we aimed to identify the role of ALR in ferroptosis induction and macrophage activation in DN. METHODS: The expression of ALR was examined in DN patients, db/db DN mice, and HK-2 cells treated with high glucose (HG). The effects of ALR on ferroptosis and macrophage activation were investigated with ALR conditional knockout, lentivirus transfection, transmission electron microscopy, qRT-PCR and western blotting assay. Mass spectrometry and rescue experiments were conducted to determine the mechanism of ALR. RESULTS: ALR expression was reduced in the kidney tissues of DN patients and mice, serum of DN patients, and HG-HK-2 cells. Moreover, the inhibition of ALR promoted ferroptosis, macrophage activation, and DN progression. Mechanistically, ALR can directly bind to carnitine palmitoyltransferase-1A (CPT1A), the key rate-limiting enzyme of fatty acid oxidation (FAO), and inhibit the expression of CPT1A to regulate lipid metabolism involving FAO and lipid droplet-mitochondrial coupling in DN. CONCLUSION: Taken together, our findings revealed a crucial protective role of ALR in ferroptosis induction and macrophage activation in DN and identified it as an alternative diagnostic marker and therapeutic target for DN.

IFI30 as a key regulator of PDL1 immunotherapy prognosis in breast cancer.

BACKGROUND: IFI30 is a lysosomal thiol reductase involved in antigen presentation and immune regulation in various cancers, including breast cancer. Despite its known involvement, the precise mechanism, function, and relationship with the PD-L1 axis and immune response remain unclear. METHODS: We conducted an extensive investigation into IFI30 mRNA expression in breast cancer utilizing data from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases. Furthermore, we characterized IFI30 mRNA expression across various cell types using publicly available single-cell RNA sequencing datasets, and assessed protein expression through immunohistochemistry using an in-house breast cancer tissue microarray. Functional experiments were performed to elucidate the effects of IFI30 overexpression on PD-L1 expression and inhibitory efficacy in both macrophages and breast tumor cells. RESULTS: Our study unveiled a marked upregulation of IFI30 expression in breast cancer tissues compared to their normal counterparts, with notable associations identified with tumor stage and prognosis. Additionally, IFI30 expression demonstrated significant correlations with various immune-related signaling pathways, encompassing peptide antigen binding, cytokine binding, and MHC class II presentation. Notably, breast cancer samples exhibiting high IFI30 expression in tumor cells displayed high PD-L1 expression on corresponding cells, alongside a diminished ratio of CD8 + T cell infiltration within the tumor microenvironment. Furthermore, ectopic knockdown of IFI30 in both tumor cells and macrophages resulted in a reduction of PD-L1 expression, while conversely, overexpression of IFI30 led to an increase in PD-L1 expression. CONCLUSIONS: This study offers new insights into the involvement of IFI30 in breast cancer, elucidating its interplay with the PD-L1 axis and immune response dynamics. Our findings suggest that modulation of the IFI30-PD-L1 axis could serve as a promising strategy for regulating T cells infiltration in breast cancer thus treating breast cancer.

Site-specific immobilization of the endosialidase reveals QSOX2 is a novel polysialylated protein.

Polysialic acid (polySia) is a linear polymer of α2,8-linked sialic acid residues that is of fundamental biological interest due to its pivotal roles in the regulation of the nervous, immune, and reproductive systems in healthy human adults. PolySia is also dysregulated in several chronic diseases, including cancers and mental health disorders. However, the mechanisms underpinning polySia biology in health and disease remain largely unknown. The polySia-specific hydrolase, endoneuraminidase NF (EndoN), and the catalytically inactive polySia lectin EndoNDM, have been extensively used for studying polySia. However, EndoN is heat stable and remains associated with cells after washing. When studying polySia in systems with multiple polysialylated species, the residual EndoN that cannot be removed confounds data interpretation. We developed a strategy for site-specific immobilization of EndoN on streptavidin-coated magnetic beads. We showed that immobilizing EndoN allows for effective removal of the enzyme from samples, while retaining hydrolase activity. We used the same strategy to immobilize the polySia lectin EndoNDM, which enabled the enrichment of polysialylated proteins from complex mixtures such as serum for their identification via mass spectrometry. We used this methodology to identify a novel polysialylated protein, QSOX2, which is secreted from the breast cancer cell line MCF-7. This method of site-specific immobilization can be utilized for other enzymes and lectins to yield insight into glycobiology.

Comprehensive proteomics of CSF, plasma, and urine identify DDC and other biomarkers of early Parkinson's disease.

Parkinson's disease (PD) starts at the molecular and cellular level long before motor symptoms appear, yet there are no early-stage molecular biomarkers for diagnosis, prognosis prediction, or monitoring therapeutic response. This lack of biomarkers greatly impedes patient care and translational research-L-DOPA remains the standard of care more than 50 years after its introduction. Here, we performed a large-scale, multi-tissue, and multi-platform proteomics study to identify new biomarkers for early diagnosis and disease monitoring in PD. We analyzed 4877 cerebrospinal fluid, blood plasma, and urine samples from participants across seven cohorts using three orthogonal proteomics methods: Olink proximity extension assay, SomaScan aptamer precipitation assay, and liquid chromatography-mass spectrometry proteomics. We discovered that hundreds of proteins were upregulated in the CSF, blood, or urine of PD patients, prodromal PD patients with DAT deficit and REM sleep behavior disorder or anosmia, and non-manifesting genetic carriers of LRRK2 and GBA mutations. We nominate multiple novel hits across our analyses as promising markers of early PD, including DOPA decarboxylase (DDC), also known as L-aromatic acid decarboxylase (AADC), sulfatase-modifying factor 1 (SUMF1), dipeptidyl peptidase 2/7 (DPP7), glutamyl aminopeptidase (ENPEP), WAP four-disulfide core domain 2 (WFDC2), and others. DDC, which catalyzes the final step in dopamine synthesis, particularly stands out as a novel hit with a compelling mechanistic link to PD pathogenesis. DDC is consistently upregulated in the CSF and urine of treatment-naïve PD, prodromal PD, and GBA or LRRK2 carrier participants by all three proteomics methods. We show that CSF DDC levels correlate with clinical symptom severity in treatment-naïve PD patients and can be used to accurately diagnose PD and prodromal PD. This suggests that urine and CSF DDC could be a promising diagnostic and prognostic marker with utility in both clinical care and translational research.

SUMF1 overexpression promotes tumorous cell growth and migration and is correlated with the immune status of patients with glioma.

BACKGROUND: Glioma is a prevalent type of malignant tumor. To date, there is a lack of literature reports that have examined the association between sulfatase modifying factor 1 (SUMF1) and glioma. METHODS: The levels of SUMF1 were examined, and their relationships with the diagnosis, prognosis, and immune microenvironment of patients with glioma were investigated. Cox and Lasso regression analysis were employed to construct nomograms and risk models associated with SUMF1. The functions and mechanisms of SUMF1 were explored and verified using gene ontology, cell counting kit-8, wound healing, western blotting, and transwell experiments. RESULTS: SUMF1 expression tended to increase in glioma tissues. SUMF1 overexpression was linked to the diagnosis of cancer, survival events, isocitrate dehydrogenase status, age, and histological subtype and was positively correlated with poor prognosis in patients with glioma. SUMF1 overexpression was an independent risk factor for poor prognosis. SUMF1-related nomograms and high-risk scores could predict the outcome of patients with glioma. SUMF1 co-expressed genes were involved in cytokine, T-cell activation, and lymphocyte proliferation. Inhibiting the expression of SUMF1 could deter the proliferation, migration, and invasion of glioma cells through epithelial mesenchymal transition. SUMF1 overexpression was significantly associated with the stromal score, immune cells (such as macrophages, neutrophils, activated dendritic cells), estimate score, immune score, and the expression of the programmed cell death 1, cytotoxic T-lymphocyte associated protein 4, CD79A and other immune cell marker. CONCLUSION: SUMF1 overexpression was found to be correlated with adverse prognosis, cancer detection, and immune status in patients with glioma. Inhibiting the expression of SUMF1 was observed to deter the proliferation, migration, and invasion of cancer cells. The nomograms and risk models associated with SUMF1 could predict the prognosis of patients with glioma.

Sulfide quinone oxidoreductase contributes to voltage sensing of the mitochondrial permeability transition pore.

Pathological opening of the mitochondrial permeability transition pore (mPTP) is implicated in the pathogenesis of many disease processes such as myocardial ischemia, traumatic brain injury, Alzheimer's disease, and diabetes. While we have gained insight into mPTP biology over the last several decades, the lack of translation of this knowledge into successful clinical therapies underscores the need for continued investigation and use of different approaches to identify novel regulators of the mPTP with the hope of elucidating new therapeutic targets. Although the mPTP is known to be a voltage-gated channel, the identity of its voltage sensor remains unknown. Here we found decreased gating potential of the mPTP and increased expression and activity of sulfide quinone oxidoreductase (SQOR) in newborn Fragile X syndrome (FXS) mouse heart mitochondria, a model system of coenzyme Q excess and relatively decreased mPTP open probability. We further found that pharmacological inhibition and genetic silencing of SQOR increased mPTP open probability in vitro in adult murine cardiac mitochondria and in the isolated-perfused heart, likely by interfering with voltage sensing. Thus, SQOR is proposed to contribute to voltage sensing by the mPTP and may be a component of the voltage sensing apparatus that modulates the gating potential of the mPTP.

DDAH1 recruits peroxiredoxin 1 and sulfiredoxin 1 to preserve its activity and regulate intracellular redox homeostasis.

Growing evidence suggests that dimethylarginine dimethylaminohydrolase 1 (DDAH1), a crucial enzyme for the degradation of asymmetric dimethylarginine (ADMA), is closely related to oxidative stress during the development of multiple diseases. However, the underlying mechanism by which DDAH1 regulates the intracellular redox state remains unclear. In the present study, DDAH1 was shown to interact with peroxiredoxin 1 (PRDX1) and sulfiredoxin 1 (SRXN1), and these interactions could be enhanced by oxidative stress. In HepG2 cells, H2O2-induced downregulation of DDAH1 and accumulation of ADMA were attenuated by overexpression of PRDX1 or SRXN1 but exacerbated by knockdown of PRDX1 or SRXN1. On the other hand, DDAH1 also maintained the expression of PRDX1 and SRXN1 in H2O2-treated cells. Furthermore, global knockout of Ddah1 (Ddah1-/-) or liver-specific knockout of Ddah1 (Ddah1HKO) exacerbated, while overexpression of DDAH1 alleviated liver dysfunction, hepatic oxidative stress and downregulation of PRDX1 and SRXN1 in CCl4-treated mice. Overexpression of liver PRDX1 improved liver function, attenuated hepatic oxidative stress and DDAH1 downregulation, and diminished the differences between wild type and Ddah1-/- mice after CCl4 treatment. Collectively, our results suggest that the regulatory effect of DDAH1 on cellular redox homeostasis under stress conditions is due, at least in part, to the interaction with PRDX1 and SRXN1.

[Knockdown of interferon-γ inducible protein 30 (IFI30) inhibits the proliferation, invasion and migration of human glioma U251 cells by activating STAT1 and promotes their apoptosis].

Objective To establish U251 cells with inhibited expression of interferon-γ inducible protein 30 (IFI30), and to investigate the effect of IFI30 on cell biological function as well as its underlying mechanism. Methods Three knockdown sequences which target IFI30 were designed online and 3 small interfering RNAs (siRNA) were synthesized. After transfection, the inhibition efficiency was detected by real-time quantitative PCR. The siRNA sequence with the highest inhibition efficiency was selected to create short hairpin RNA (shRNA) plasmids. The recombinant plasmids and packaging plasmids were co-transfected into HEK293T cells to prepare lentivirus. The glioma U251 cells were transfected with lentivirus, and the positive cells were screened by puromycin. CCK-8 assay, 5-ethyl-2'-deoxyuridine (EdU) and colony formation assays were used to analyze cell proliferation; the flow cytometry was used to analyze cell cycle and apoptosis; the TranswellTM assay was used to detect cell invasion; the wound-healing assay was employed to detect cell migration, and western blot analysis to detect the protein expresison of cyclin D1, B-cell lymphoma factor 2 (Bcl2), epithelial cadherin (E-cadherin), neural cadherin (N-cadherin), signal transducer and activator of transcription 1 (STAT1). Results The sequence which effectively target IFI30 was screened and U251 cell line capable of inhibiting the IFI30 expression was successfully established. When IFI30 expression was knocked down, the proliferation of U251 cells was inhibited, along with increased ratio of cells in the phase G0/G1, the decreased phase S, the increased rate of cell apoptosis. The cell invasion and migration capabilities was also reduced. The decreased expression of cyclin D1, Bcl2 and N-cadherin were observed in U251 cells, and the expression of E-cadherin and the phosphorylation of STAT1 were found increased. Conclusion Knockdown of IFI30 inhibits the proliferation, invasion and migration of human glioma cell U251 and promotes its apoptosis by activating STAT1.

Biochemical signatures of disease severity in multiple sulfatase deficiency.

Sulfatases catalyze essential cellular reactions, including degradation of glycosaminoglycans (GAGs). All sulfatases are post-translationally activated by the formylglycine generating enzyme (FGE) which is deficient in multiple sulfatase deficiency (MSD), a neurodegenerative lysosomal storage disease. Historically, patients were presumed to be deficient of all sulfatase activities; however, a more nuanced relationship is emerging. Each sulfatase may differ in their degree of post-translational modification by FGE, which may influence the phenotypic spectrum of MSD. Here, we evaluate if residual sulfatase activity and accumulating GAG patterns distinguish cases from controls and stratify clinical severity groups in MSD. We quantify sulfatase activities and GAG accumulation using three complementary methods in MSD participants. Sulfatases differed greatly in their tolerance of reduction in FGE-mediated activation. Enzymes that degrade heparan sulfate (HS) demonstrated lower residual activities than those that act on other GAGs. Similarly, HS-derived urinary GAG subspecies preferentially accumulated, distinguished cases from controls, and correlated with disease severity. Accumulation patterns of specific sulfatase substrates in MSD provide fundamental insights into sulfatase regulation and will serve as much-needed biomakers for upcoming clinical trials. This work highlights that biomarker investigation of an ultra-rare disease can simultaneously inform our understanding of fundamental biology and advance clinical trial readiness efforts.

Development of tandem antigen capture ELISAs measuring QSOX1 isoforms in plasma and serum.

QSOX1 is a sulfhydryl oxidase that has been identified as a potential biomarker in multiple cancer types as well as acute decompensated heart failure. Three anti-QSOX1 monoclonal antibodies (mAbs) were generated: 2F1, 3A10, and 56-3. MAbs 2F1 and 3A10 were generated against the short isoform of recombinant QSOX1 (rQSOX1-S), and mAb 56-3 was generated against a peptide (NEQEQPLGQWHLS) from the long isoform of QSOX1 (QSOX1-L). Using these mAbs, tandem antigen capture ELISAs were developed to quantify both short and long isoforms of QSOX1 (Total QSOX1 ELISA) and QSOX1-L (QSOX1-L ELISA) in serum and plasma samples. The Total QSOX1 ELISA pairs mAbs 2F1 and 3A10 and has a limit of detection of 109.5 pM, while the QSOX1-L ELISA pairs mAbs 2F1 and 56-3 and has a limit of detection of 10 pM. The levels of total QSOX1 and QSOX1-L were measured in a cohort of paired sera and plasma from 61 donors ≥40 years old and 15 donors <40 years old. No difference in QSOX1 levels was detected between QSOX1-L and QSOX1-S in serum, but the mean concentration of QSOX1-L was found to be 3.21 nM in serum and 5.63 nM in plasma (**p = 0.006). Our tandem ELISAs demonstrate the wide range of concentrations of QSOX1-L and QSOX1-S among individual serum and plasma samples. Since the epitope of mAb 2F1 was mapped to the first CxxC motif at residues C70 and C73 and mAb 56-3 was generated against NEQEQPLGQWHLS in QSOX1-L, our findings support previous research which suggested that QSOX1-L is secreted from cells despite a putative transmembrane domain. The ELISAs reported here may be a useful tool for investigating QSOX1 isoforms as potential biomarkers in cancer and/or heart failure.