Mitochondrial TrxR2 regulates metabolism and protects from metabolic disease through enhanced TCA and ETC function

Mitochondrial dysfunction is a key driver of diabetes and other metabolic diseases. Mitochondrial redox state is highly impactful to metabolic function but the mechanism driving this is unclear. We generated a transgenic mouse which overexpressed the redox enzyme Thioredoxin Reductase 2 (TrxR2), the rate limiting enzyme in the mitochondrial thioredoxin system. We found augmentation of TrxR2 to enhance metabolism in mice under a normal diet and to increase resistance to high-fat diet induced metabolic dysfunction by both increasing glucose tolerance and decreasing fat deposition. We show this to be caused by increased mitochondrial function which is driven at least in part by enhancements to the tricarboxylic acid cycle and electron transport chain function. Our findings demonstrate a role for TrxR2 and mitochondrial thioredoxin as metabolic regulators and show a critical role for redox enzymes in controlling functionality of key mitochondrial metabolic systems.

Nanoformulation of Talazoparib Increases Maximum Tolerated Doses in Combination With Temozolomide for Treatment of Ewing Sarcoma

The Pediatric Preclinical Testing Program previously identified the PARP inhibitor talazoparib (TLZ) as a means to potentiate temozolomide (TMZ) activity for the treatment of Ewing sarcoma. However, the combination of TLZ and TMZ has been toxic in both preclinical and clinical testing, necessitating TMZ dose reduction to ~15% of the single agent maximum tolerated dose. We have synthesized a nanoparticle formulation of talazoparib (NanoTLZ) to be administered intravenously in an effort to modulate the toxicity profile of this combination treatment. Results in Ewing sarcoma xenograft models are presented to demonstrate the utility of this delivery method both alone and in combination with TMZ. NanoTLZ reduced gross toxicity and had a higher maximum tolerated dose than oral TLZ. The dose of TMZ did not have to be reduced when combined with NanoTLZ as was required when combined with oral TLZ. This indicated the NanoTLZ delivery system may be advantageous in decreasing the systemic toxicity associated with the combination of oral TLZ and TMZ.

Dual targeting of androgen receptor and mTORC1 by salinomycin in prostate cancer

Androgen receptor (AR) and PI3K/AKT/mTORC1 are major survival signals that drive prostate cancer to a lethal disease. Reciprocal activation of these oncogenic pathways from negative cross talks contributes to low/limited success of pathway-selective inhibitors in curbing prostate cancer progression. We report that the antibiotic salinomycin, a cancer stem cell blocker, is a dual-acting AR and mTORC1 inhibitor, inhibiting PTEN-deficient castration-sensitive and castration-resistant prostate cancer in culture and xenograft tumors. AR expression, its transcriptional activity, and androgen biosynthesis regulating enzymes CYP17A1, HSD3β1 were reduced by sub-micro molar salinomycin. Estrogen receptor-α expression was unchanged. Loss of phosphorylated AR at serine-81, which is an index for nuclear AR activity, preceded total AR reduction. Rapamycin enhanced the AR protein level without altering phosphoAR-Ser81 and CYP17A1. Inactivation of mTORC1, evident from reduced phosphorylation of mTOR and downstream effectors, as well as AMPK activation led to robust autophagy induction. Apoptosis increased modestly, albeit significantly, by sub-micro molar salinomycin. Enhanced stimulatory TSC2 phosphorylation at Ser-1387 by AMPK, and reduced inhibitory TSC2 phosphorylation at Ser-939/Thr-1462 catalyzed by AKT augmented TSC2/TSC1 activity, which led to mTORC1 inhibition. AMPK-mediated raptor phosphorylation further reduced mTOR's kinase function and mTORC1 activity. Our novel finding on dual inhibition of AR and mTORC1 suggests that salinomycin is potentially active as monotherapy against advanced prostate cancer.

Anticancer applications of allosteric inhibitors of proteasome

e23066

Background: Proteasome as a hub protease of the ubiquitin proteasome pathway is an established anticancer drug target. Several drugs that inhibit proteasome are currently used to successfully treat aggressive blood cancers. These drugs are based on their competition with protein substrates of proteasome. However, efficacy of these drugs toward solid cancers is inadequate. Besides, the side effects and developing drug resistance are increasingly hampering the therapy. Therefore, there is an unmet challenge to develop new types of proteasome targeting compounds that are efficient against solid cancers and utilize other mechanisms to stop proteasome. Here we present a compound with a novel molecular mechanism, potentially bypassing limitations of the available drugs. Methods: We rationally designed and synthesized a series of small molecule “B” compounds, derivatives of a binding domain of seco-rapamycin that noncompetitively interfere with peptidase activities of proteasome. We tested effects of the compounds in vitro on purified proteasome, in cellulo with selected cancer cell lines and in a xenograft mouse model of prostate cancer. Results: We found that compound B1 binds to the catalytic core of proteasome far from the catalytic sites, destabilizes assembly of the 26S proteasome responsible for digest of polyUb substrates and allosterically inhibits its proteolytic activities. Molecularly, B1 impedes the gating mechanism responsible for substrate uptake as found with AFM. Tryptophan fluorescence indicates that B1 changes proteasome fold and the binding mode of competitive inhibitors. B1 substantially decreases viability of selected cancer cell lines and shifts their mechanical phenotype toward noncancerous status. B1 synergizes with bortezomib decreasing the IC50 5-10 fold. In a xenograft hormone resistant prostate cancer model, B1 treatment leads to shrinkage of the tumor size, decreases enumeration of aggressive, EpCAM+ CTCs and shifts the macrophage profile toward predator M1 type. Conclusions: B1 compounds constitute a new class of noncompetitive allosteric inhibitors of proteasome that could be useful to develop to treat aggressive prostate cancers alone or in synergy with competitive inhibitors.

Brief Assessment of Parental Perception (BAPP): Development and validation of a new measure for assessing paediatric outcomes after bilateral cochlear implantation

OBJECTIVE

In contrast to previous clinical practice, current guidelines recommend bilateral cochlear implantation in children, resulting in a cohort of children who initially received one implant, but have subsequently had a second, contralateral implant. This study aimed to explore satisfaction and quality of life in children implanted simultaneously or sequentially.

DESIGN

A novel measure of satisfaction and quality of life following paediatric bilateral cochlear implantation (the Brief Assessment of Parental Perception; BAPP) was developed and preliminary validation undertaken as part of a large, national project of bilateral implantation. Children's parents completed the measure yearly for up to three years following implantation.

STUDY SAMPLE

Children from 14 UK implant centres were recruited into the study; data were available for 410 children one year post-implantation.

RESULTS

The BAPP was found to have good face and convergent validity, and internal consistency. Results indicated very high levels of satisfaction with the devices, and improvements in quality of life. However there was evidence that children implanted sequentially were less willing to wear their second implant in the first two years than those children receiving simultaneous implants.

CONCLUSION

Simultaneous and sequential cochlear implants have a positive impact on the quality of life of deaf children.

Nuclear Receptors in Drug Metabolism, Drug Response and Drug Interactions

Orally delivered small-molecule therapeutics are metabolized in the liver and intestine by phase I and phase II drug-metabolizing enzymes (DMEs), and transport proteins coordinate drug influx (phase 0) and drug/drug-metabolite efflux (phase III). Genes involved in drug metabolism and disposition are induced by xenobiotic-activated nuclear receptors (NRs), i.e. PXR (pregnane X receptor) and CAR (constitutive androstane receptor), and by the 1α, 25-dihydroxy vitamin D3-activated vitamin D receptor (VDR), due to transactivation of xenobiotic-response elements (XREs) present in phase 0-III genes. Additional NRs, like HNF4-α, FXR, LXR-α play important roles in drug metabolism in certain settings, such as in relation to cholesterol and bile acid metabolism. The phase I enzymes CYP3A4/A5, CYP2D6, CYP2B6, CYP2C9, CYP2C19, CYP1A2, CYP2C8, CYP2A6, CYP2J2, and CYP2E1 metabolize >90% of all prescription drugs, and phase II conjugation of hydrophilic functional groups (with/without phase I modification) facilitates drug clearance. The conjugation step is mediated by broad-specificity transferases like UGTs, SULTs, GSTs. This review delves into our current understanding of PXR/CAR/VDR-mediated regulation of DME and transporter expression, as well as effects of single nucleotide polymorphism (SNP) and epigenome (specified by promoter methylation, histone modification, microRNAs, long non coding RNAs) on the expression of PXR/CAR/VDR and phase 0-III mediators, and their impacts on variable drug response. Therapeutic agents that target epigenetic regulation and the molecular basis and consequences (overdosing, underdosing, or beneficial outcome) of drug-drug/drug-food/drug-herb interactions are also discussed. Precision medicine requires understanding of a drug's impact on DME and transporter activity and their NR-regulated expression in order to achieve optimal drug efficacy without adverse drug reactions. In future drug screening, new tools such as humanized mouse models and microfluidic organs-on-chips, which mimic the physiology of a multicellular environment, will likely replace the current cell-based workflow.

Factors associated with a difficult induction of general anaesthesia

BACKGROUND

Many children experiencing a procedure under general anaesthetic (GA), including those having surgery for cochlear implantation, display behaviours indicative of distress during induction of anaesthesia. It would be useful to ascertain which factors in the pre-operative period are related to the presence of distress at induction in order to target appropriate psychological preparation.

METHODS

The families of 84 children aged 4-7 years undergoing a procedure under GA (including insertion of a cochlear implant) completed three questionnaires assessing temperament, behavioural difficulties, and pre-operative worries. Demographic variables were also recorded. The outcome measure was the amount of behavioural distress at induction.

RESULTS

Statistically significant relationships with the outcome measure of distress at induction were obtained for three factors; an emotional or sociable temperament, and the number of previous procedures. Further, children receiving inhalation inductions displayed greater distress than those receiving intravenous inductions.

CONCLUSION

Undergoing cochlear implantation under GA is a major life event for many recipients. Psychologically preparing children for this has been found to be efficacious, but is not currently available to all children. It is suggested that preparation can be targeted at children, as identified in this study, who have elevated emotionality or sociability scores or who have previous experience of procedures under general anaesthesia. This is of particular current relevance as children are increasingly likely to require re-implantation as they grow older and as unilaterally implanted children are now being offered a sequential bilateral implant, both necessitating further surgery.

Developmental expression of Toll-like receptors-2 and -4 in preterm baboon lung

Preterm babies are susceptible to respiratory infection due to immature lung and immune system. Immune cells express Toll-like receptors (TLRs), which may be important in local host defense of preterm infants. We studied the expression of TLR2 and TLR4 in lung tissues of fetal baboons delivered at 125, 140, and 175 days of gestation (dGA; term=185+/-2 days) and preterm baboons that became naturally infected with bacterial/fungal pathogens. The TLR-mRNA and protein were quantified by Northern and Western blotting, respectively. The expression of both TLRs was significantly low at 125 and 140dGA. At 175dGA, the levels reached equivalent to those in adult baboons. However, in naturally infected baboons, the TLR4-mRNA was reduced (p<0.05); TLR2-mRNA expression remained unaltered. The protein expression of both TLRs was found increased in naturally infected baboons. Our results suggest that the lung TLR expression is developmentally regulated and altered during respiratory infection in preterm babies.

Partial and whole gene deletion mutations of the GCK and HNF1A genes in maturity-onset diabetes of the young

AIMS/HYPOTHESIS

Heterozygous mutations of glucokinase (GCK) and hepatocyte nuclear factor-1 alpha (HNF1A; also known as hepatic transcription factor 1 [TCF1]) genes are the most common cause of MODY. Genomic deletions of the HNF1B (also known as TCF2) gene have recently been shown to account for one third of mutations causing renal cysts and diabetes syndrome. We investigated the prevalence of partial and whole gene deletions in UK patients meeting clinical criteria for GCK or HNF-1alpha/-4alpha MODY and in whom no mutation had been identified by sequence analysis.

METHODS

A multiplex ligation-dependent probe amplification (MLPA) assay was developed using synthetic oligonucleotide probes for 30 exons of the GCK, HNF1A and HNF4A genes.

RESULTS

Partial or whole gene deletions were identified in 1/29 (3.5%) probands using the GCK MLPA assay and 4/60 (6.7%) of probands using the HNF1A/-4A MLPA assay. Four different deletions were detected: GCK exon 2, HNF1A exon 1, HNF1A exons 2 to 10 and HNF1A exons 1 to 10. An additional Danish pedigree with evidence of linkage to HNF1A had a deletion of exons 2 to 10. Testing other family members confirmed co-segregation of the deletion mutations with diabetes in the pedigrees.

CONCLUSIONS/INTERPRETATION

Large deletions encompassing whole exons can cause GCK or HNF-1alpha MODY and will not be detected by sequencing. Gene dosage assays, such as MLPA, are a useful adjunct to sequence analysis when a diagnosis of MODY is strongly suspected.

Expression of TLR2 and TLR4 in Preterm Baboon Lung (B165)

Respiratory infections can cause significant morbidity and mortality in prematurely delivered babies. The increased susceptibility of preterm babies to infection is related to immaturity of the immune system. The Toll-like receptors (TLR) are expressed by antigen-presenting cells and play a key role in recognition of pathogens and regulation of immune response. However, their role in preterm babies is not well-understood. In this study, we investigated the expression of TLR2 and TLR4 proteins in lung tissues of fetal (delivered at 125, 140, 175 days of gestation age, dGA; complete term 185 days) and naturally-infected, prematurely delivered (125dGA ventilated with PRN O2) baboons. The expression of TLR2 and TLR4 was studied at protein level by Western blotting using anti-human-TLR2 and TLR4 antibodies. We found that the expression of TLR2 and TLR4 protein increased with the gestational age; the expression was found low in lung tissues of 125dGA baboon which increased to adult level at 175dGA. But in the lung tissues of naturally-infected preterm baboons, the protein levels of both TLR2 and TLR4 were significantly increased as compared to non-infected controls. Our results suggest that the expression of TLR2 and TLR4 is developmentally regulated and it may play a significant role in regulation of immune responses during infection in preterm babies.

Research Support by American Lung Association

Immunophenotype and functions of fetal baboon bone-marrow derived dendritic cells

Dendritic cells (DCs) are unique antigen-presenting cells that can take up pathogens, pathogens-derived and stress-antigens and stimulate antigen-specific immune response. Here we investigated the immunobiology of fetal DCs and compared their phenotype and activation status against infectious stimuli with those of young and adult baboons. The DCs were obtained from femoral bone-marrow (BMDCs) of fetus (140 and 175 days of gestation), young (4-5 years old) and mature adult (10-35 years old) baboons. The cells were cultured in the presence of GM-CSF and IL-4. To study phagocytic ability of BMDCs, the cells were harvested on 6th day and incubated with fluorescent-labeled Escherichia coli bioparticles. The BMDCs were also treated with E. coli O111:B4 lipopolysaccharide (LPS) for 24h and changes in expression of cell-surface markers and IL-12 were studied using distinct immunoassays. We found that the phenotype and morphology of BMDCs from fetal, young and adult baboons were similar and showed increased expression of HLA-DP, DQ, DR and T cell co-stimulatory molecules upon LPS treatment. However, significant differences were observed in phagocytic activity and IL-12 secretion among BMDCs from these sources. The ability of fetal baboon BMDCs to phagocytose E. coli bioparticles was significantly lower and they secreted lower level of LPS-stimulated IL-12 as compared to the BMDCs from adult baboon. These results suggest that compared to adult BMDCs, fetal baboon BMDCs are less efficient in mounting immune response against Gram-negative bacterial stimuli.

The use of a screening questionnaire to identify children with likely asthma

BACKGROUND

The theory that airway remodeling and possible fixed asthma may result from failure to treat asthma airway inflammation highlights the importance of the early identification of patients with likely asthma.

AIM

To identify children with likely asthma whose condition is unknown to the medical services.

STUDY

Postal questionnaire survey.

SETTING

Children in two general practice populations in 1999.

METHOD

Parents completed the postal questionnaire surveys. Two validated scoring systems were used to identify children with 'likely asthma': first, three or more positive responses to five key questions; second, three or more positive responses to the same five questions and one more severe symptom (e.g. exercise-induced wheeze). Questionnaire responses were linked to practice records to determine those with a recorded diagnosis of asthma (ever) or of inhaled medication (past 12 months).

RESULTS

Using the first scoring system, 22.5% of children were identified as having likely asthma; more than one-third of these (35.1%) had no corroborative evidence recorded in the practice records. With the second system, 15.5% had likely asthma, a quarter of whom had no corroborative evidence. Depending on the scoring system chosen, between 3.5% and 8% of children in these practices had likely asthma but no corroborative evidence in their records.

CONCLUSIONS

Children identified using either of these scoring systems would require full clinical assessment to determine their need for medical intervention. These findings have implications for the allocation of health care resources.