4E-BP1 counteracts human mesenchymal stem cell senescence via maintaining mitochondrial homeostasis

Although the mTOR-4E-BP1 signaling pathway is implicated in aging and aging-related disorders, the role of 4E-BP1 in regulating human stem cell homeostasis remains largely unknown. Here, we report that the expression of 4E-BP1 decreases along with the senescence of human mesenchymal stem cells (hMSCs). Genetic inactivation of 4E-BP1 in hMSCs compromises mitochondrial respiration, increases mitochondrial reactive oxygen species (ROS) production, and accelerates cellular senescence. Mechanistically, the absence of 4E-BP1 destabilizes proteins in mitochondrial respiration complexes, especially several key subunits of complex III including UQCRC2. Ectopic expression of 4E-BP1 attenuates mitochondrial abnormalities and alleviates cellular senescence in 4E-BP1-deficient hMSCs as well as in physiologically aged hMSCs. These f indings together demonstrate that 4E-BP1 functions as a geroprotector to mitigate human stem cell senescence and maintain mitochondrial homeostasis, particularly for the mitochondrial respiration complex III, thus providing a new potential target to counteract human stem cell senescence.

BCS1Neonatal growth retardation and lactic acidosis initiated by novel mutation sites in L gene / 中华预防医学杂志

This study aims to analyze the clinical characteristics and genetic variations of two cases with developmental delay and lactic acidosis in a family, and to explore the relationship between genetic variations and clinical features. A retrospective analysis was conducted on the clinical characteristics of two siblings with developmental delay and lactic acidosis who were treated at the Neonatal Department of Children's Hospital of Chongqing Medical University in May 2019 and December 2021, respectively. Whole-exome sequencing was used to detect genetic variations in the affected children. Homology modeling of the BCS1L protein was performed to analyze the structural and functional changes of the protein. The correlation between genetic variations and clinical phenotypes was analyzed. The results showed that the main clinical features of the two affected children in this family were manifestations of mitochondrial respiratory chain complex Ⅲ deficiency, including prematurity, developmental delay, respiratory failure, lactic acidosis, cholestasis, liver dysfunction, renal tubular lesions, coagulation dysfunction, anemia, hypoglycemia, hypotonia, and early death. Whole-exome sequencing revealed a novel deletion mutation c.486_488delGGA (p.E163del) and a novel missense mutation c.992C>T (p.T331I) in the BCS1L gene. Structural analysis of the homology modeling showed that the compound heterozygous mutation had a significant impact on protein function. In conclusion, the novel mutation site c.992C>T (p.T331I) in the BCS1L gene is a "likely pathogenic" mutation, and the compound heterozygous mutation is closely related to the phenotype of mitochondrial respiratory chain complex Ⅲ deficiency.

Reduced semen quality in patients with testicular cancer seminoma is associated with alterations in the expression of sperm proteins / 亚洲男科学杂志(英文版)

Testicular cancer seminoma is one of the most common types of cancer among men of reproductive age. Patients with this condition usually present reduced semen quality, even before initiating cancer therapy. However, the underlying mechanisms by which testicular cancer seminoma affects male fertility are largely unknown. The aim of this study was to investigate alterations in the sperm proteome of men with seminoma undergoing sperm banking before starting cancer therapy, in comparison to healthy proven fertile men (control group). A routine semen analysis was conducted before cryopreservation of the samples (n = 15 per group). Men with seminoma showed a decrease in sperm motility (P = 0.019), total motile count (P = 0.001), concentration (P = 0.003), and total sperm count (P = 0.001). Quantitative proteomic analysis identified 393 differentially expressed proteins between the study groups. Ten proteins involved in spermatogenesis, sperm function, binding of sperm to the oocyte, and fertilization were selected for validation by western blot. We confirmed the underexpression of heat shock-related 70 kDa protein 2 (P = 0.041), ubiquinol-cytochrome C reductase core protein 2 (P = 0.026), and testis-specific sodium/potassium-transporting ATPase subunit alpha-4 (P = 0.016), as well as the overexpression of angiotensin I converting enzyme (P = 0.005) in the seminoma group. The altered expression levels of these proteins are associated with spermatogenesis dysfunction, reduced sperm kinematics and motility, failure in capacitation and fertilization. The findings of this study may explain the decrease in the fertilizing ability of men with seminoma before starting cancer therapy.

Insights into cytochrome bc1 complex binding mode of antimalarial 2-hydroxy-1, 4-naphthoquinones through molecular modelling

BACKGROUND Malaria persists as a major public health problem. Atovaquone is a drug that inhibits the respiratory chain of Plasmodium falciparum, but with serious limitations like known resistance, low bioavailability and high plasma protein binding. OBJECTIVES The aim of this work was to perform molecular modelling studies of 2-hydroxy-1,4-naphthoquinones analogues of atovaquone on the Qo site of P. falciparum cytochrome bc1 complex (Pfbc1) to suggest structural modifications that could improve their antimalarial activity. METHODS We have built the homology model of the cytochrome b (CYB) and Rieske iron-sulfur protein (ISP) subunits from Pfbc1 and performed the molecular docking of 41 2-hydroxy-1,4-naphthoquinones with known in vitro antimalarial activity and predicted to act on this target. FINDINGS Results suggest that large hydrophobic R2 substituents may be important for filling the deep hydrophobic Qo site pocket. Moreover, our analysis indicates that the H-donor 2-hydroxyl group may not be crucial for efficient binding and inhibition of Pfbc1 by these atovaquone analogues. The C1 carbonyl group (H-acceptor) is more frequently involved in the important hydrogen bonding interaction with His152 of the Rieske ISP subunit. MAIN CONCLUSIONS Additional interactions involving residues such as Ile258 and residues required for efficient catalysis (e.g., Glu261) could be explored in drug design to avoid development of drug resistance by the parasite.

Mitochondrial UQCRB as a new molecular prognostic biomarker of human colorectal cancer

Ubiquinol cytochrome c reductase binding protein (UQCRB) is important for mitochondrial complex III stability, electron transport, cellular oxygen sensing and angiogenesis. However, its potential as a prognostic marker in colorectal cancer (CRC) remains unclear. The aim of this study was to determine whether UQCRB can be used as a diagnostic molecular marker for CRC. The correlation between the expression of three genes (UQCRB, UQCRFS1 and MT-CYB) in the mitochondrial respiratory chain complex III and clinico-pathological features was determined. Compared to non-tumor tissues, UQCRB gene expression was upregulated in CRC tissues. Gene and protein expression of the genes were positively correlated. Copy number variation (CNV) differences in UQCRB were observed in CRC tissues (1.32-fold) compared to non-tumor tissues. The CNV of UQCRB in CRC tissues increased proportionally with gene expression and clinical stage. Single-nucleotide polymorphisms in the 3′-untranslated region of UQCRB (rs7836698 and rs10504961) were investigated, and the rs7836698 polymorphism was associated with CRC clinical stage. DNA methylation of the UQCRB promoter revealed that most CRC patients had high methylation levels (12/15 patients) in CRC tissues compared to non-tumor tissues. UQCRB overexpression and CNV gain were correlated with specific CRC clinico-pathological features, indicating clinical significance as a prognostic predictor in CRC. Gene structural factors may be more important than gene transcription repression factors with respect to DNA methylation in UQCRB overexpression. Our results provide novel insights into the critical role of UQCRB in regulating CRC, supporting UQCRB as a new candidate for the development of diagnostics for CRC patients.

Analysis of UQCRB gene mutation in a child with mitochondrial complex III deficiency / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To delineate the clinical, biochemical and genetic mutational characteristics of a child with mitochondrial complex III deficiency.</p><p><b>METHODS</b>Clinical information and results of auxiliary examination of the patient were analyzed. Next-generation sequencing of the mitochondrial genome and related nuclear genes was carried out. Suspected mutation was confirmed in both parents with Sanger sequencing. Heterozygous deletion was mapped with chromosomal microarray analysis and confirmed with real-time PCR.</p><p><b>RESULTS</b>The patient presented with vomiting, polypnea, fever, metabolic acidosis, hyperlactatemia, hypoglycemia, dysfunction of coagulation and immune system, in addition with increased lactate dehydrogenase and creatine kinase isoenzyme. Elevation of blood alanine and acylcarnitines as well as urinary ketotic dicarboxylic acid were also noted. The patient also presented development delay, mental retardation and hypotonia. Sequence analysis revealed two mutations in the nuclear gene UQCRB, which included a previously reported frameshift mutation c.306_309delAAAA(p.Arg105Lysfs*22) and a novel large deletion encompassing the entire UQCRB gene.</p><p><b>CONCLUSION</b>The clinical, biochemical and gene mutation characteristics of a child with mitochondrial complex III deficiency caused by mutations of the UQCRB gene have been delineated.</p>

Fiebre chikungunya en México: caso confirmado y apuntes para la respuesta epidemiológica / Chikungunya fever in Mexico: confirmed case and notes on the epidemiologic response

La fiebre chikungunya (CHIK) es una enfermedad viral transmitida al ser humano por el mismo vector del dengue, el mosquito Aedes. Además de fiebre y fuertes dolores articulares, produce otros síntomas como mialgias, cefalea, náuseas, cansancio y exantema. No tiene tratamiento específico; el manejo terapéutico de los pacientes se enfoca en el alivio de los síntomas. Históricamente se han reportado brotes de grandes proporciones; incluso desde 2010 se llegó a considerar como una potencial epidemia emergente. En 2013 se introdujo a las islas del Caribe y recientemente se ha reportado en el continente americano. En este trabajo se describe el primer caso confirmado de chikungunya en México, en el municipio de Tlajomulco de Zúñiga, Jalisco, en mayo de 2014, importado de la isla Antigua y Barbuda, en el Caribe, por una mujer de 39 años de edad.

Chikungunya fever (CHIK) is a viral disease transmitted to human beings by the same vector as dengue -the Aedes mosquito. Besides fever and severe pain in the joints, it produces other symptoms such as myalgias, headache, nausea, fatigue and exanthema. There is no specific treatment for it; the therapeutic management of patients focuses on symptom relief. Historically, outbreaks of large proportions have been reported; even since 2010 it was considered to be a potential emerging epidemic. In 2013 it was introduced into the islands of the Caribbean, and it has recently been reported in the American continent. This paper describes the first confirmed case of chikungunya in Mexico -in the municipality of Tlajomulco de Zúñiga, Jalisco, in May, 2014-, which was imported from the Caribbean island of Antigua and Barbuda by a 39 year-old woman.

Enzyme analysis of isolated mitochondrial respiratory chain complex III deficiency / 中华儿科杂志

<p><b>OBJECTIVE</b>To study the clinical and enzymological characteristics of the children with mitochondrial respiratory chain complex III deficiency.</p><p><b>METHOD</b>The clinical manifestations of five patients (3 males, 2 females) were summarized. Spectrophotometric assay was used for the analysis of respiratory chain complex I to V enzyme activity in peripheral blood leukocytes, after obtaining venous blood.</p><p><b>RESULT</b>(1) Five patients were hospitalized at the age of 1 month to 15 years. Three patients had Leigh syndrome with progressive motor developmental delay or regression and weakness. One had severe liver damage and intrahepatic cholestasis. One presented muscle weakness. (2) Deficient complex I + III activity was identified in five patients. Their complex I + III activities in peripheral blood leukocytes were 3.0 to 14.2 nmol/min per mg mitochondrial protein (control: 84.4 ± 28.5 nmol/min per mg mitochondrial protein). The ratio of complex I + III to citrate synthase decreased to 3.5 to 22.9% (normal control 66.1 ± 14.7%). The activities of complex III decreased to 10.4 to 49.3% of the lowest control value, while complex I, II, IV and V activities were normal. The results supported the diagnosis of isolated respiratory chain complex III deficiency.</p><p><b>CONCLUSION</b>Complex III deficiency is a kind of disorder of energy metabolism with various manifestations. The complex I + III activities and the ratio of complex I + III to citrate synthase were lower than those of the control. The activities of complex I, II, IV and V were normal.</p>

Effects of bushen yinao tablet on physiology and cerebral gene expression in senescence-accelerated mice / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To study the effects of Bushen Yin' ao Tablet (BSYNT) on physiology and cerebral gene expression in senescence-accelerated mice (SAM).</p><p><b>METHODS</b>The change of cerebral tissues mRNA expression in SAM was analyzed and compared by messenger ribonucleic acids reverse transcription differential display polymerase chain reaction (mRNA DDRT-PCR) between the medicated group and the control group.</p><p><b>RESULTS</b>BSYNT could increase the level of hemoglobin (Hb) and amount of erythrocyte (RBC) of blood deficiency mice, improve the spatial learning and memory function and the escape response by conditional stimulus. In this study, 14 differential display bands had been discerned, and three of them had been sequenced. The sequence of the three fragments was similar to fatty acid binding protein 7, ubiquinol-cytochrome C reductase complex (7. 2 kD) and 60S ribosomal protein L21 respectively. And the homogeneity was 97% , 100% , and 99% , respectively.</p><p><b>CONCLUSION</b>BSYNT has effect on the physiological changing of mice, and its effect on cerebral tissues mRNA expression maybe play an important role in anti-aging on the molecular level.</p>

Complejos de vanadio (III) con glutatión en disolución acuosa / Vanadium (III) complexes with glutathione in aqueous solution

Se presentan los resultados del estudio de los complejos de vanadio(III) con glutatión (GSH, H3L) a 25 °C y en KCl3,0 M mediante medidas de fuerzas electromotrices, emf(H). El análisis de los datos mediante el programa de mínimos cuadrados generalizados LETAGROP indica la formación de cantidades significativas de los complejos VH4l4+, VH3L3+, V(H3L)23+ yv(L)(3L)2+, cuyas constantes de estabilidad fueron determinadas.

The formation of the vanadium(III) complexes with glutathione (GSH, H3L) was studied in 3.0 M KCl at 25 °C by means of electromotive forces measurements, emf (H). The analysis of the potentiometric data by means of the least-squares program LETAGROP indicates the formation of significant quantities of the complexes VH4l4+, VH3L3+, V(H3L)23+ yv(L)(3L)2+, whose stability constants were determined.

Study of mitochondrial enzymes: cytochrome c oxidoreductase [complex III], and cytochrome oxidase [complex IV] with copper-zinc containing superoxide dismutase [SOD1] in children with down syndrome

Neither the pathogenesis nor the etiology of Down Syndrome [DS] are clearly understood. There is no evidence however that individual loci are responsible, or that the oxidative damage in DS could be solely explained by a gene dosage effect. Oxidative stress resulting from mitochondrial dysfunction may implicate the role of mitochondrial genome in DS pathogenesis and etiology. Moreover, the early Alzheimer's disease [AD] in DS is attributed to defective mitochondrial enzymes. The aim of the present work was to estimate the activity of mitochondrial electron transport enzymes cytochrome c oxidoreductase [complex III], cytochrome c-oxidase [complex IV] and copper-zinc containing superoxide dismutase [SOD-1] enzymes in children with Down syndrome and compare them with those of the normal children. The study was carried out on 30 Down syndrome children diagnosed by karyotyping and typical healthy children served as controls. Estimation of complex III, complex IV and Cu-Zn containing dismutase enzymes activities were done using spectrophotometeric methods. The results showed that there was a significant increase in the activity of SOD-1 in Down syndrome children compared to normal children with significant increase in DS children 5 years had significantly lower complex III activity than controls. DS children with epilepsy had significantly higher mean activity of SOD-1 than DS children without epilepsy. Both SOD-1 and complex III had significant inverse correlation with head circumference and there was no correlation between the three studied enzymes and the presence of congenital heart defects. Deficiency of the studied mitochondrial respiratory enzymes associated with increase in the activity of superoxide dismutase are a consequence of a generalized mitochondrial disturbance which may lie behind some pathogenetic aspects of Down syndrome and could contribute to impairment of energy metabolism and neurodegeneration, observed in DS

Effects of yinxing pingchan recipe and its components on activity of mitochondrial enzyme complex in brain of mice with Parkinson's disease / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To investigate the mechanisms of Yinxing Pingchan recipe (YXPC) and its components, i.e. the components for detoxicating (A), for calming liver (B) and for dissolving blood stasis(C), in preventing and treating Parkinson's disease, and the path of its inhibition on nigrostriatal dopaminergic neuron (DAn) apoptosis in model mice of Parkinson's disease.</p><p><b>METHODS</b>Male C57BL/6J mice were divided into the normal group, the model group and four Chinese medicinal groups, that is, the YXPC group, and Group A, B and C, treated with YXPC and its components A, B and C respectively. Mouse model of Parkinson's disease was established by intraperitoneal injection with 1-methl-4-phenyl-1,2,3,6-tetrahydropyridin (MPTP). All mice were sacrificed in 2 batches at the 14th and the 28th day respectively. The activity of mitochondrial enzyme complex I, II and IV (MEC I, II and IV) in the brain of mice were measured, respectively.</p><p><b>RESULTS</b>As compared with the normal group, the activity of MEC I and IV in brain was significantly lower (P < 0.05 or P < 0.01), and that of MEC II had no obvious change in the model group. As compared with the model group, the activity of MEC I was significantly higher in YXPC group and Group C at the 14th day (P < 0.05), while the activity of MECII in Group A at the 14th day, Group B at the 28th day and Group C at both 14th and 28th day was significantly lower (P<0.05 or P<0.01). Activity of MEC IV in the four Chinese medicinal groups at the 14th day all significantly increased (P<0.05 or P<0.01), and retained at high level in Group B and Group C at the 28th day (P<0.05).</p><p><b>CONCLUSION</b>YXPC and its components can maintain the mitochondrial function by partial inhibiting the activity of its enzyme complex, preventing DAn apoptosis to slow down the progress of Parkinson's disease.</p>

Overexpression and reconstitution of a Rieske iron-sulfur protein from the cyanobacterium Synechocystis PCC 6803.

Chloroplast cyt b6f complexes as well as mitochondrial and bacterial cyt bc1 complexes contain a high potential Rieske iron-sulfur protein which is essential for their function. To characterise the isolated Rieske protein from the mesophilic cyanobacterium Synechocystis PCC6803 we cloned the encoding gene into an expression vector and overexpressed the protein in E. coli. In cells overexpressing the protein no typical Rieske type EPR signal was detected neither in membranes nor in inclusion bodies where the majority of the protein was deposited. The inclusion bodies were isolated from the E. coli cells and denaturated with 8 M urea. With a single anion exchange chromatographic step a pure protein could be obtained which was used for further experiments. The NifS like protein IscS was recently reported to mediate the incorporation of iron-sulfur clusters into ferredoxin in vitro. We used the recombinant IscS protein for the incorporation of the cluster into the folded Rieske apoprotein. Spectroscopic characterisation of the resultant protein by CD and EPR spectroscopy showed the presence of a typical Rieske iron-sulfur centre.

Mitochondrial cytochrome b gene in two developmental stages of human malarial parasite Plasmodium falciparum.

The cytochrome b gene of the mitochondrial ubiquinol-cytochrome c reductase (complex III of electron transport chain) was characterized in two developmental stages of human malarial parasite cultivated in vitro. The cytochrome b gene spanning the nucleotide position 4691 to 5930 in 6-kb mitochondrial DNA from gametocytic (sexual) and intraerythrocytic (asexual) stages of Plasmodium falciparum (a T9,94 mutant line) were in vitro amplified from total DNA using polymerase chain reaction (PCR). It was found that the parasites from both stages contained the PCR product approximately 1.2 kb in length that was localized in mitochondria. The nucleotide sequences of cytochrome b gene at Qi/quinone binding site from both stages were analyzed using thermal cycle sequencing and were found to be the same. The amount of this gene from both stages of the parasite were determined by using the quantitative PCR method. The results showed that the amount of the cytochrome b gene produced from the sexual stage was seven times higher than that obtained from the asexual stage. Our results would provide basic information on the regulation of cytochrome b and the 6-kb mitochondrial DNA during growth and development of the sexual and asexual stages of the malarial parasite in the mammalian host.