Deoxyguanosine kinase deficiency: natural history and liver transplant outcome.

Autosomal recessive pathogenetic variants in the DGUOK gene cause deficiency of deoxyguanosine kinase activity and mitochondrial deoxynucleotides pool imbalance, consequently, leading to quantitative and/or qualitative impairment of mitochondrial DNA synthesis. Typically, patients present early-onset liver failure with or without neurological involvement and a clinical course rapidly progressing to death. This is an international multicentre study aiming to provide a retrospective natural history of deoxyguanosine kinase deficient patients. A systematic literature review from January 2001 to June 2023 was conducted. Physicians of research centres or clinicians all around the world caring for previously reported patients were contacted to provide followup information or additional clinical, biochemical, histological/histochemical, and molecular genetics data for unreported cases with a confirmed molecular diagnosis of deoxyguanosine kinase deficiency. A cohort of 202 genetically confirmed patients, 36 unreported, and 166 from a systematic literature review, were analyzed. Patients had a neonatal onset (≤ 1 month) in 55.7% of cases, infantile (>1 month and ≤ 1 year) in 32.3%, pediatric (>1 year and ≤18 years) in 2.5% and adult (>18 years) in 9.5%. Kaplan-Meier analysis showed statistically different survival rates (P < 0.0001) among the four age groups with the highest mortality for neonatal onset. Based on the clinical phenotype, we defined four different clinical subtypes: hepatocerebral (58.8%), isolated hepatopathy (21.9%), hepatomyoencephalopathy (9.6%), and isolated myopathy (9.6%). Muscle involvement was predominant in adult-onset cases whereas liver dysfunction causes morbidity and mortality in early-onset patients with a median survival of less than 1 year. No genotype-phenotype correlation was identified. Liver transplant significantly modified the survival rate in 26 treated patients when compared with untreated. Only six patients had additional mild neurological signs after liver transplant. In conclusion, deoxyguanosine kinase deficiency is a disease spectrum with a prevalent liver and brain tissue specificity in neonatal and infantile-onset patients and muscle tissue specificity in adult-onset cases. Our study provides clinical, molecular genetics and biochemical data for early diagnosis, clinical trial planning and immediate intervention with liver transplant and/or nucleoside supplementation.

Mitochondrial deoxyguanosine kinase is required for female fertility in mice.

Mitochondrial homeostasis plays a pivotal role in oocyte maturation and embryonic development. Deoxyguanosine kinase (DGUOK) is a nucleoside kinase that salvages purine nucleosides in mitochondria and is critical for mitochondrial DNA replication and homeostasis in non-proliferating cells. Dguok loss-of-function mutations and deletions lead to hepatocerebral mitochondrial DNA deletion syndrome. However, its potential role in reproduction remains largely unknown. In this study, we find that Dguok knockout results in female infertility. Mechanistically, DGUOK deficiency hinders ovarian development and oocyte maturation. Moreover, DGUOK deficiency in oocytes causes a significant reduction in mitochondrial DNA copy number and abnormal mitochondrial dynamics and impairs germinal vesicle breakdown. Only few DGUOK-deficient oocytes can extrude their first polar body during in vitro maturation, and these oocytes exhibit irregular chromosome arrangements and different spindle lengths. In addition, DGUOK deficiency elevates reactive oxygen species levels and accelerates oocyte apoptosis. Our findings reveal novel physiological roles for the mitochondrial nucleoside salvage pathway in oocyte maturation and implicate DGUOK as a potential marker for the diagnosis of female infertility.

LncRNA DGUOK-AS1 Promotes Cell Progression in Lung Squamous Cell Carcinoma by Regulation of miR-653-5p/SLC6A15 Axis.

Long noncoding RNA (lncRNA) plays a key role in regulating cancer development. LncRNA deoxyguanosine kinase antisense RNA 1 (DGUOK-AS1) has been reported as a promoter in tumor. The work was designed to further investigate the mechanism of action of DGUOK-AS1 in lung squamous cell carcinoma (LUSC). DGUOK-AS1 level in LUSC cells was measured using RT-qPCR. Counting Kit-8 assays and colony forming assays were performed to evaluate LUSC cell viability and proliferation. Transwell assays were performed to detect cell migration and invasion. Luciferase reporter and RNA pulldown assays were used to verify the binding capacity of DGUOK-AS1 and miR-653-5p. RNA immunoprecipitation assays were performed to verify the relationship of DGUOK-AS1, miR-653-5p, and SLC6A15. DGUOK-AS1 was highly expressed in LUSC cells. DGUOK-AS1 knockdown suppressed LUSC cell proliferation, migration, and invasion. SLC6A15 was demonstrated to be targeted by miR-653-5p, and DGUOK-AS1 interacted with miR-653-5p to modulate SLC6A15 level in LUSC cells. Overexpression of SLC6A15 reversed the suppressive effects of DGUOK-AS1 knockdown on LUSC cell processes. In conclusion, DGUOK-AS1 promotes malignant behaviors of LUSC cells by upregulating SLC6A15 level through interaction with miR-653-5p.

Considerations for liver transplantation in deoxyguanosine kinase deficiency: A case series and review of the literature.

BACKGROUND: Deoxyguanosine kinase (DGUOK) deficiency is a rare mitochondrial disorder characterized by early onset liver failure and varying degrees of neurologic dysfunction. Patients typically present during infancy with progressive hepatic dysfunction leading to liver failure, which can precede neurologic deterioration. Outcomes posttransplantation are historically worse than average and the role of liver transplantation remains controversial. These factors, in combination with the increasing number of patients being diagnosed via molecular genetic testing, may impede waitlist access. METHODS: We report our single-center experience with three patients with DGUOK deficiency, all of whom were considered for transplant. We review the current literature regarding management and discuss the role of liver transplantation in DGUOK deficiency-associated liver failure. RESULTS: Two patients presented with hypoglycemia, conjugated hyperbilirubinemia, and lactic acidosis within the first week of life, were diagnosed with DGUOK deficiency prior to 2 months of age and had severe neurologic involvement. The third patient presented in later infancy was diagnosed with DGUOK deficiency at 18 months of age and had minimal neurologic involvement. All three patients were considered for transplant, though only two patients were listed. All three died from complications of end-stage liver failure prior to liver transplantation between the ages of 5-20 months. CONCLUSION: Selection for liver transplantation in DGUOK deficiency is complex, requiring a multidisciplinary team approach. Recent data suggest that liver transplantation can be successful in select patients with absent or mild neurologic manifestations. National databases reporting long-term outcomes posttransplantation are needed.

Case report: Two unexpected cases of DGUOK-related mitochondrial DNA depletion syndrome presenting with hyperinsulinemic hypoglycemia.

Timely diagnosis of persistent neonatal hypoglycemia is critical to prevent neurological sequelae, but diagnosis is complicated by the heterogenicity of the causes. We discuss two cases at separate institutions in which clinical management was fundamentally altered by the results of molecular genetic testing. In both patients, critical samples demonstrated hypoketotic hypoglycemia and a partial glycemic response to glucagon stimulation, thereby suggesting hyperinsulinism (HI). However, due to rapid genetic testing, both patients were found to have deoxyguanosine kinase (DGUOK)-related mitochondrial DNA depletion syndrome, an unexpected diagnosis. Patients with this disease typically present with either hepatocerebral disease in the neonatal period or isolated hepatic failure in infancy. The characteristic features involved in the hepatocerebral form of the disease include lactic acidosis, hypoglycemia, cholestasis, progressive liver failure, and increasing neurologic dysfunction. Those with isolated liver involvement experience hepatomegaly, cholestasis, and liver failure. Although liver transplantation is considered, research has demonstrated that for patients with DGUOK-related mitochondrial DNA depletion syndrome and neurologic symptoms, early demise occurs. Our report advocates for the prompt initiation of genetic testing in patients presenting with persistent neonatal hypoglycemia and for the incorporation of mitochondrial DNA depletion syndromes in the differential diagnosis of HI.

Case report: Novel DGUOK variants associated with idiopathic non-cirrhotic portal hypertension in a Han Chinese child.

DGUOK deficiency has primarily been associated with lethal hepatic failure with or without hypotonia, nystagmus, and psychomotor retardation, features typical of mitochondrial disease. A study in 3 Turkish children identified homozygosity for a variant in DGUOK as associated with idiopathic non-cirrhotic portal hypertension (INCPH). However, no further instances of INCPH associated with DGUOK variants have been reported. We here describe a fourth patient with DGUOK variants and childhood-onset INCPH, a 12-year-old Han Chinese boy, reporting clinical manifestations, histopathologic findings, and results of genetic studies. The child presented with hepatosplenomegaly; portal hypertension and hypersplenism were found. Vascular changes with hepatic fibrosis (Scheuer score 3) were observed on liver biopsy. Whole-exome sequencing and family analyses revealed compound heterozygosity for the DGUOK (NM_080916.3) variants c.778_781dup, (p.Thr261Serfs*28) and c.831_832del, (p.*278Thrfs*9) in the proband. These observations support ascription of instances of INCPH in children to variation in DGUOK.

Mitochondrial depletion syndrome type 3: the Lebanese variant.

Introduction: Mitochondrial DNA depletion syndrome type 3 is an emerging disorder linked to variants in the deoxyguanosine kinase gene, which encodes for mitochondrial maintenance. This autosomal recessive disorder is frequent in the Middle East and North Africa. Diagnosis is often delayed due to the non-specificity of clinical presentation with cerebro-hepatic deterioration. The only therapeutic option is liver transplantation, although the value of this remains debatable. Methods: We describe the clinical, biochemical, and molecular profiles of Lebanese patients with this rare disorder. We also present a review of all cases from the Middle East and North Africa. Results: All Lebanese patients share a unique mutation, unreported in other populations. Almost half of patients worldwide originate from the Middle East and North Africa, with cases reported from only 7 of the 21 countries in this region. Clinical presentation is heterogeneous, with early-onset neurological and hepatic signs. Liver failure and lactic acidosis are constants. Several variants can be identified in each population; a unique c.235C>T p. (Gln79*) pathogenic variant is found in Lebanese patients. Outcome is poor, with death before 1 year of age. Conclusion: The pathogenic nonsense variant c.235C>T p. (Gln79*) in the deoxyguanosine kinase gene may be considered a founder mutation in Lebanon. Further genotypic delineation of this devastating disorder in populations with high consanguinity rates is needed.

LncRNA DGUOK-AS1 facilitates non-small cell lung cancer growth and metastasis through increasing TRPM7 stability via m6A modification.

BACKGROUND: N6-methyladenosine (m6A) modification plays key roles in tumor progression. LncRNA deoxyguanosine kinase antisense RNA 1 (DGUOK-AS1) has been reported as a promoter in tumors, but its role and mechanism in non-small cell lung cancer (NSCLC) development remain uncertain. METHODS: Cell proliferation, migration, invasion and angiogenesis were investigated via CCK-8, colony formation, transwell, and tube formation assays, respectively. The location of DGUOK-AS1 was detected via FISH assay. The interaction relationship among DGUOK-AS1, IGF2BP2 and TRPM7 was confirmed by RIP and MeRIP assays. The effects of DGUOK-AS1 on NSCLC growth and metastasis in vivo were investigated using xenograft and pulmonary metastatic models. RESULTS: DGUOK-AS1 was upregulated in NSCLC. DGUOK-AS1 silencing inhibited NSCLC cell proliferation, migration, invasion and angiogenesis. DGUOK-AS1 was mostly expressed in cytoplasm, and positively regulated IGF2BP2. METTL3/IGF2BP2 axis could increase TRPM7 mRNA stability in m6A-dependent manner. TRPM7 overexpression reversed the inhibitive function of DGUOK-AS1 silencing on NSCLC development. DGUOK-AS1 knockdown suppressed NSCLC cell growth and metastasis in nude mice. CONCLUSION: DGUOK-AS1 silencing restrains NSCLC cell growth and metastasis through decreasing TRPM7 stability via regulation of the METTL3/IGF2BP2-mediated m6A modification.

Discovery and Functional Characterization of Two Regulatory Variants Underlying Lupus Susceptibility at 2p13.1.

Genome-wide association studies have identified 2p13.1 as a prominent susceptibility locus for systemic lupus erythematosus (SLE)­a complex, multisystem autoimmune disease. However, the identity of underlying causal variant (s) and molecular mechanisms for increasing disease susceptibility are poorly understood. Using meta-analysis (cases = 10,252, controls = 21,604) followed by conditional analysis, bioinformatic annotation, and eQTL and 3D-chromatin interaction analyses, we computationally prioritized potential functional variants and subsequently experimentally validated their effects. Ethnicity-specific meta-analysis revealed striking allele frequency differences between Asian and European ancestries, but with similar odds ratios. We identified 20 genome-wide significant (p < 5 × 10−8) variants, and conditional analysis pinpointed two potential functional variants, rs6705628 and rs2272165, likely to explain the association. The two SNPs are near DGUOK, mitochondrial deoxyguanosine kinase, and its associated antisense RNA DGUOK-AS1. Using luciferase reporter gene assays, we found significant cell type- and allele-specific promoter activity at rs6705628 and enhancer activity at rs2272165. This is supported by ChIP-qPCR showing allele-specific binding with three histone marks (H3K27ac, H3K4me3, and H3K4me1), RNA polymerase II (Pol II), transcriptional coactivator p300, CCCTC-binding factor (CTCF), and transcription factor ARID3A. Transcriptome data across 28 immune cell types from Asians showed both SNPs are cell-type-specific but only in B-cells. Splicing QTLs showed strong regulation of DGUOK-AS1. Genotype-specific DGOUK protein levels are supported by Western blots. Promoter capture Hi-C data revealed long-range chromatin interactions between rs2272165 and several nearby promoters, including DGUOK. Taken together, we provide mechanistic insights into how two noncoding variants underlie SLE risk at the 2p13.1 locus.

DGUOK-AS1 acts as a tumorpromoter through regulatingmiR-204-5p/IL-11 axis in breast cancer.

Breast cancer is one of the most lethal malignancies among women; however, the underlying molecular mechanism involved in the progression and metastasis of breast cancer remains unclear. Numerous studies have confirmed that long noncoding RNAs are abnormally expressed in breast cancer and play crucial roles in cell proliferation and metastasis. In the study, we evaluated the functional role and detailed mechanism of DGUOK-AS1 in breast cancer progression and metastasis. DGUOK-AS1 knockdown suppressed proliferation, migration, and invasion of breast cancer cells in vitro and in vivo. Mechanistically, miR-204-5p was identified as an inhibitory target of DGUOK-AS1, which served as a tumor suppressor in breast cancer. Significantly, we found that the ectopic expression of miR-204-5p could counteract DGUOK-AS1-mediated promotion of cell proliferation and metastasis in breast cancer. Moreover, IL-11 was found to be the downstream target of miR-204-5p, and DGUOK-AS1 could protect IL-11 from miR-204-5p-mediated degradation. DGUOK-AS1 overexpression promoted breast cancer cell migration, angiogenesis, and macrophage migration, mediating by the increased secretion of IL-11, which was extremely important for cancer progression. Collectively, our studies reveal that DGUOK-AS1/miR-204-5p/IL-11 axis plays a significant role in the progression and metastasis of breast cancer, and DGUOK-AS1 might be a novel biomarker and therapeutic target for breast cancer.

DGUOK-AS1 promotes cervical squamous cell carcinoma progression by suppressing miR-499a-5p that targets SPRR1B in vitro.

PURPOSE: Cervical squamous cell carcinoma (CESC) is the most common cancer type of cervical cancer, which threatens women's life seriously. LncRNA DGUOK-AS1has been reported to promote the biologic processes of CESC. We aim to figure out the role of DGUOK-AS1-miR-499a-5p-SPRR1B axis in modulating the CESC progression in vitro. METHODS: The levels of DGUOK-AS1, miR-499a-5p, and SPRR1B in CESC tissues and cells were examined by RT-qPCR. The interaction of DGUOK-AS1-miR-499a-5p-SPRR1B was verified by luciferase assay. Inhibition of DGUOK-AS1, miR-499a-5p, and SPRR1B was applied for exploring the biological function based on detection of cell viability, proliferation, migration, and apoptosis in CESC SiHa and HeLa cells. RESULTS: DGUOK-AS1 and SPRR1B expressions were obviously elevated, whereas the expression of miR-499a-5p was reduced in both CESC tissues and cells. Silencing of DGUOK-AS1 attenuated cell growth and boosted apoptosis of CESC cells. Notably, DGUOK-AS1 inhibited miR-499a-5p to release SPRR1B, which significantly accelerated the development of CESC. CONCLUSION: DGUOK-AS1sponging miR-499a-5p facilitated CESC cells progression by releasing SPRR1B in vitro. It provides a new sight for the treatment of CESC patients involving DGUOK-AS1-miR-499a-5p-SPRR1B.

The clinical variations and diagnostic challenges of deoxyguanosine kinase deficiency: a descriptive case series.

OBJECTIVES: Deoxyguanosine kinase (DGUOK) deficiency is one of the leading causes of the mitochondrial DNA-depletion syndromes (MDDS) associated with hepatocerebral involvement. Herein, we present four cases of DGUOK deficiency to emphasize the clinical variability of disease and the challenges in the diagnosis of DGUOK deficiency. CASE PRESENTATION: Hepatomegaly, hyperlactatemia, elevated alpha fetoprotein (AFP), alanine, and transaminase levels were detected in all patients, and cholestasis, coagulopathy, and hypotonia were common findings. All patients had a low birth weight, one patient underwent liver transplantation (LT). Clinical and laboratory findings of two patients and one patient suggested neonatal hemochromatosis and type 1 tyrosinemia, respectively. All patients were diagnosed with DGUOK deficiency by performing molecular genetic analysis. CONCLUSIONS: Mitochondrial DNA-depletion syndromes should be kept in mind in cases in which hypotonicity, lactic acidosis, and neonatal cholestasis are observed. DGUOK deficiency may present in different clinics suggesting neonatal hemochromatosis or tyrosinemia type 1.

Acute liver failure due to DGUOK deficiency-is liver transplantation justified?

BACKGROUND: Deoxyguanosine kinase (DGUOK) deficiency is one of the causes of the hepatocerebral form of mitochondrial depletion syndrome (MDS). It is characterized by an early onset of liver failure with concomitant neurological deterioration. In the current literature, there are only few reports regarding long-term observation of children with DGUOK deficiency. Liver transplantation (LTx) is controversial due to extrahepatic involvement and unpredictable outcome. METHODS: Five patients (2 boys) from 4 different families with hepatocerebral MDS associated with DGUOK mutations diagnosed with liver failure were treated in our hospital between 2010-2019. RESULTS: In all children clinical symptoms developed within the first days of live and hypoglycemia (hypoketotic), conjugated hyperbilirubinemia (cholestasis), severe lactic acidosis, and coagulopathy were observed. Two neonates had low birth-weight for gestational age and failed to thrive. Mild neurological involvement as hypotonia was observed in all children. Three children died at the age of 2, 6 months and 6,5 months of age, respectively, due to end-stage liver failure. In one case, LTx was not considered, in two patients (sisters) parents did not agree to this procedure. LTx was subsequently performed in two patients at the age of 6 and 7 months, respectively, one from deceased, and one from living related donor, in both before the final confirmation of DGUOK mutations. One boy died 2 months after LTx due to post-LTx procedure-related complications; one is still alive with 3years of follow-up, with good liver function and mild neurological disturbances. The diagnosis of DGUOK deficiency was confirmed by biallelic DGUOK mutations detection. Equally, patients were compound heterozygotes (three cases) and homozygotes (two cases). Three known molecular variants, including regulatory substitutions (c.1A>G, c.3G>A) and in-frame insertion (c.813_814insTTT) were identified. CONCLUSIONS: Prognosis in patients with DGUOK deficiency is generally poor. Based on a review of the literature and our experience liver transplantation in selected patients with DGUOK mutation does not appear to be contraindicated, especially in those without or with minimal neurologic abnormalities.

Identification of DGUOK-AS1 as a Prognostic Factor in Breast Cancer by Bioinformatics Analysis.

Background: Significant developments have been made in breast cancer diagnosis and treatment, yet the prognosis remains unsatisfactory. Accumulating evidence indicates that long non-coding RNAs (lncRNAs) play pivotal roles in the development and progression of human tumors. However, the regulatory mechanisms and clinical significance of most lncRNAs in breast cancer remain poorly understood. Methods: The lncRNA, miRNA, and mRNA expression profiles were obtained from the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) databases. A lncRNA-miRNA-mRNA regulatory network was constructed and visualized using Cytoscape. The protein-protein interaction (PPI) network was constructed using the STRING database and hub genes were extracted using the cytoHubba plugin. Gene Ontology and Kyoto Encyclopedia of Gene and Genomes analyses identified the functions and signaling pathways associated with these differentially expressed mRNAs (DEmRNAs). Expression of the key lncRNA and the relationship with prognosis of patients with breast cancer were evaluated. Results: Six differentially expressed lncRNAs (DElncRNAs), 29 differentially expressed miRNAs (DEmiRNAs), and 253 DEmRNAs were selected to construct the regulatory network. A PPI network was established and seven hub genes were identified. A lncRNA-miRNA-hub gene regulatory sub-network was established containing two DElncRNAs, five DEmiRNAs, and seven DEmRNAs. Hub genes were associated with breast cancer onset and progression. The upregulated DGUOK-AS1 was identified as the key lncRNA in breast cancer based on the competing endogenous RNA network. High DGUOK-AS1 expression was associated with adverse prognosis in patients with breast cancer and a prognostic nomogram built on Grade, LN status, and DGUOK-AS1 expression shows significant prognostic value. Conclusions: Our results reveal the significant roles of lncRNA/miRNA/mRNA regulatory networks in breast cancer and identified a novel prognosis predictor and promising therapeutic target for patients with breast cancer.

Clinical and molecular basis of hepatocerebral mitochondrial DNA depletion syndrome in Japan: evaluation of outcomes after liver transplantation.

BACKGROUND: Hepatocerebral mitochondrial DNA depletion syndrome (MTDPS) is a disease caused by defects in mitochondrial DNA maintenance and leads to liver failure and neurological complications during infancy. Liver transplantation (LT) remains controversial due to poor outcomes associated with extrahepatic symptoms. The purposes of this study were to clarify the current clinical and molecular features of hepatocerebral MTDPS and to evaluate the outcomes of LT in MTDPS patients in Japan. RESULTS: We retrospectively assessed the clinical and genetic findings, as well as the clinical courses, of 23 hepatocerebral MTDPS patients from a pool of 999 patients who were diagnosed with mitochondrial diseases between 2007 and 2019. Causative genes were identified in 18 of 23 patients: MPV17 (n = 13), DGUOK (n = 3), POLG (n = 1), and MICOS13 (n = 1). Eight MPV17-deficient patients harbored c.451dupC and all three DGUOK-deficient patients harbored c.143-307_170del335. The most common initial manifestation was failure to thrive (n = 13, 56.5%). The most frequent liver symptom was cholestasis (n = 21, 91.3%). LT was performed on 12 patients, including nine MPV17-deficient and two DGUOK-deficient patients. Among the 12 transplanted patients, five, including one with mild intellectual disability, survived; while seven who had remarkable neurological symptoms before LT died. Five of the MPV17-deficient survivors had either c.149G > A or c.293C > T. CONCLUSIONS: MPV17 was the most common genetic cause of hepatocerebral MTDPS. The outcome of LT for MTDPS was not favorable, as previously reported, however, patients harboring MPV17 mutations associated with mild phenotypes such as c.149G > A or c.293C > T, and exhibiting no marked neurologic manifestations before LT, had a better prognosis after LT.

Pediatric liver transplantation from a living donor in mitochondrial disease: Good outcomes in DGUOK deficiency?

DGUOK deficiency is an autosomal recessive mitochondrial disorder characterized by hepatic and neurological manifestations. In patients with liver failure, the decision to perform LT can be difficult due to the likelihood of progressive neurological disease. We present a case of a 9-month-old boy who had DGUOK deficiency (E227K/R118H genotype) intact neurological status and liver failure. His MRI indicated extensive white matter changes, which created hesitation to perform LT. After a multidisciplinary evaluation, he underwent LT from a living donor at 11 months of age. Six years post-transplant, he has had no significant complications and no progression of neurological symptoms. Our case supports that even in the presence of neurological MRI findings, but in the absence of significant neurological symptoms, LT represents a viable option in DGUOK-deficient patients who have the E227K/R118H mutation combination along with liver failure.

DGUOK-AS1 promotes cell proliferation in cervical cancer via acting as a ceRNA of miR-653-5p.

Cervical cancer (CC) holds the second highest incidence and is the fourth dominating cause of cancer-induced death in women. It has been widely accepted that long noncoding RNAs (lncRNAs) are implicated in pathological and physiological activities of CC. However, the research of lncRNAs is still in the initial stage. The biological function of lncRNA deoxyguanosine kinase antisense RNA 1 (DGUOK-AS1) in human cancers has not been reported yet. We found that DGUOK-AS1 was aberrantly upregulated in cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) tissues through TCGA database. Real-time quantitative polymerase chain reaction (RT-qPCR) also verified the high expression of DGUOK-AS1 in CC cell lines. Loss-of-function assays indicated that DGUOK-AS1 silence repressed CC cell growth. In addition, dual-luciferase reporter and RNA immunoprecipitation (RIP) experiments validated the binding relation between miR-653-5p and DGUOK-AS1 or EMSY. Results of the rescue assays elucidated that EMSY overexpression or miR-653-5p downregulation reversed the suppressive function of DGUOK-AS1 knockdown on cell growth and DNA repair in CC. To sum up, this research highlighted that DGUOK-AS1 could promote CC cell proliferation via serving as a ceRNA of miR-653-5p to release EMSY, which might inspire us to discover novel strategies for CC treatment. SIGNIFICANCE OF THE STUDY: DGUOK-AS1 knockdown hinders proliferation of CC cells. DGUOK-AS1 sequesters miR-653-5p to elevate EMSY in CC. EMSY is required for DGUOK-AS1 to induce cell proliferation and repress DNA damage in CC.

Clinical and molecular characterization of three patients with Hepatocerebral form of mitochondrial DNA depletion syndrome: a case series.

BACKGROUND: Mitochondrial DNA depletion syndromes (MDS) are clinically and phenotypically heterogeneous disorders resulting from nuclear gene mutations. The affected individuals represent a notable reduction in mitochondrial DNA (mtDNA) content, which leads to malfunction of the components of the respiratory chain. MDS is classified according to the type of affected tissue; the most common type is hepatocerebral form, which is attributed to mutations in nuclear genes such as DGUOK and MPV17. These two genes encode mitochondrial proteins and play major roles in mtDNA synthesis. CASE PRESENTATION: In this investigation patients in three families affected by hepatocerebral form of MDS who were initially diagnosed with tyrosinemia underwent full clinical evaluation. Furthermore, the causative mutations were identified using next generation sequencing and were subsequently validated using sanger sequencing. The effect of the mutations on the gene expression was also studied using real-time PCR. A pathogenic heterozygous frameshift deletion mutation in DGUOK gene was identified in parents of two affected patients (c.706-707 + 2 del: p.k236 fs) presenting with jaundice, impaired fetal growth, low-birth weight, and failure to thrive who died at the age of 3 and 6 months in family I. Moreover, a novel splice site mutation in MPV17 gene (c.461 + 1G > C) was identified in a patient with jaundice, muscle weakness, and failure to thrive who died due to hepatic failure at the age of 4 months. A 5-month-old infant presenting with jaundice, dark urine, poor sucking, and feeding problems was also identified to have another novel mutation in MPV17 gene leading to stop gain mutation (c.277C > T: p.(Gln93*)). CONCLUSIONS: These patients had overlapping clinical features with tyrosinemia. MDS should be considered a differential diagnosis in patients presenting with signs and symptoms of tyrosinemia.

The mitochondrial deoxyguanosine kinase is required for cancer cell stemness in lung adenocarcinoma.

The mitochondrial deoxynucleotide triphosphate (dNTP) is maintained by the mitochondrial deoxynucleoside salvage pathway and dedicated for the mtDNA homeostasis, and the mitochondrial deoxyguanosine kinase (DGUOK) is a rate-limiting enzyme in this pathway. Here, we investigated the role of the DGUOK in the self-renewal of lung cancer stem-like cells (CSC). Our data support that DGUOK overexpression strongly correlates with cancer progression and patient survival. The depletion of DGUOK robustly inhibited lung adenocarcinoma tumor growth, metastasis, and CSC self-renewal. Mechanistically, DGUOK is required for the biogenesis of respiratory complex I and mitochondrial OXPHOS, which in turn regulates CSC self-renewal through AMPK-YAP1 signaling. The restoration of mitochondrial OXPHOS in DGUOK KO lung cancer cells using NDI1 was able to prevent AMPK-mediated phosphorylation of YAP and to rescue CSC stemness. Genetic targeting of DGUOK using doxycycline-inducible CRISPR/Cas9 was able to markedly induce tumor regression. Our findings reveal a novel role for mitochondrial dNTP metabolism in lung cancer tumor growth and progression, and implicate that the mitochondrial deoxynucleotide salvage pathway could be potentially targeted to prevent CSC-mediated therapy resistance and metastatic recurrence.

Histopathological liver findings in patients with hepatocerebral mitochondrial depletion syndrome with defined molecular basis.

Mitochondrial DNA depletion consisting of the systemic reduction of mtDNA copy number in cells may have a heterogenous genetic basis, resulting from a pathogenic change in the nuclear genes involved in mtDNA synthesis. The mode of inheritance is autosomal recessive. Severe hepatocerebral disease represents one of many different clinical forms of so-called mitochondrial depletion syndrome (MDS). We present the liver histopathology of 13 children who eventually died in the course of hepatocerebral MDS confirmed molecularly, harbouring mutations of DGUOK, MPV17, and POLG genes. Material comprising eight autopsy and five liver biopsy specimens showed a moderately reproducible pattern of parenchymal damage, which we consider potentially helpful in the differential diagnosis and planning of the diagnostic investigation in families of children who died due to early-onset acute liver failure and encephalopathy.