Biology subjects

Bender, C.

Publications and source records attributed to Bender, C..

4 recordsLinked to original sources

bioRxiv2023

Neuropathy target esterase activity predicts retinopathy among PNPLA6 disorders

Biallelic pathogenic variants in the PNPLA6 gene cause a broad spectrum of disorders leading to gait disturbance, visual impairment, anterior hypopituitarism, and hair anomalies. PNPLA6 encodes Neuropathy target esterase (NTE), yet the role of NTE dysfunction on affected tissues in the large spectrum of associated disease remains unclear. We present a clinical meta-analysis of a novel cohort of 23 new patients along with 95 reported individuals with PNPLA6 variants that implicate missense variants as a driver of disease pathogenesis. Measuring esterase activity of 46 disease-associated and 20 common variants observed across PNPLA6-associated clinical diagnoses unambiguously reclassified 10 variants as likely pathogenic and 36 variants as pathogenic, establishing a robust functional assay for classifying PNPLA6 variants of unknown significance. Estimating the overall NTE activity of affected individuals revealed a striking inverse relationship between NTE activity and the presence of retinopathy and endocrinopathy. This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists. Thus, PNPLA6 disorders, previously considered allelic, are a continuous spectrum of pleiotropic phenotypes defined by an NTE genotype:activity:phenotype relationship. This relationship and the generation of a preclinical animal model pave the way for therapeutic trials, using NTE as a biomarker.

neuroscience↗

bioRxiv2022

Oral bioavailability and metabolism of hydroxytyrosol from food supplements

Table olives and olive oils are the main dietary sources of hydroxytyrosol (HT), a natural antioxidant compound that has emerged as a potential aid in protection against cardiovascular risk. Bioavailability studies with olive oils showed that HT is bioavailable from its free form and from conjugated forms like oleuropein and its aglycone. Still, its low dietary intake, poor bioavailability, and high inter-individual variability after absorption through the gastrointestinal tract hamper its full benefits. In a randomized, controlled, blind, cross-over study, we investigated the impact of HT metabolism and bioavailability by comparing two olive-derived watery supplements containing different doses of HT (30.58 and 61.48 mg of HT/dosage, respectively); additionally, HT-fortified olive oil was used in the control group. To this aim, plasma and urine samples were evaluated in 12 healthy volunteers following the intake of a single dose of the supplements or fortified olive oil. Blood and urine samples were collected at baseline and at 0.5, 1, 1.5, 2, 4, and 12 hours after intake. HT and its metabolites were analyzed by UHPLC-DAD-MS/MS. Pharmacokinetic results showed that dietary HT administered through the food supplements is bioavailable and biovailability increases with the administered dose. After intake, homovanillic acid, HT-3-O-sulfate, and 3,4-dihydroxyphenylacetic acid are the main metabolites found both in plasma and urine. The maximum concentrations in plasma peaked 30 minutes after intake. Being the bioavailability of a compound a fundamental prerequisite for its effect, these results promise a good potential of both food supplements for the protection against oxidative stress and the consequent cardiovascular risk.

physiology↗

bioRxiv2022

Bioefficacy of hydroxytyrosol-rich food supplements on preventing lipid peroxidation in healthy men

In the present study we report the efficacy of food matrices derived from olives in preventing oxidation of low-density lipoprotein cholesterol (LDL) and lipid peroxidation. To this end, 12 healthy volunteers were divided into 3 groups and cross-received a single dose of olive phenolics, mainly hydroxytyrosol (HT), provided as a liquid dietary supplement (30.6 or 61.5 mg HT), or as fortified extra virgin olive oil (12.19 mg HT + tyrosol). Blood and urine samples were collected at baseline and up to 12 hours after ingestion. Plasma oxidized LDL levels were measured by ELISA using a monoclonal antibody, while F2-isoprostanes were quantified in urine by UHPLC-MS/MS. Despite the great variability between individuals, a tendency to reduce lipoxidation reactions has been observed after olive phenolics intake in both, blood and urine. In addition, the subgroup of individuals with the highest baseline lipoxidation level showed a decrease in F2-isoprostanes (p < 0.05) after taking the food supplements, as well as a marked decrease in oxidized LDL levels (p < 0.01) after intake of the food supplement with the lowest HT dose. These promising results suggest that HT supplementation could be a useful aid in preventing lipoxidation. Additionally, people with a redox imbalance could benefit even more from supplementing with bioavailable HT.

pharmacology and toxicology↗

bioRxiv2022

Zfp503/Nlz2 is Required for RPE Differentiation and Optic Fissure Closure

PurposeUveal coloboma is a congenital eye malformation caused by failure of the optic fissure to close in early human development. Despite significant progress in identifying genes whose regulation is important for executing this closure, mutations are detected in a minority of cases using known gene panels, implying additional genetic complexity. We have previously shown knock down of znf503 (the ortholog of mouse Zfp503) in zebrafish causes coloboma. Here we characterize Zfp503 knock out (KO) mice and evaluate transcriptomic profiling of mutant vs. wild-type (WT) retinal pigment epithelium (RPE)/Choroid. MethodsZfp503 KO mice were generated by gene targeting using homologous recombination. Embryos were characterized grossly and histologically. Patterns and level of developmentally relevant proteins/genes were examined with immunostaining/in situ hybridization. The transcriptomic profile of E11.5 KO RPE/choroid was compared to that of WT. ResultsZfp503 is dynamically expressed in developing mouse eyes and that loss of its expression results in uveal coloboma. KO embryos exhibit altered mRNA levels and expression patterns of several key transcription factors involved in eye development, including Otx2, Mitf, Pax6, Pax2, Vax1 and Vax2, resulting in reduced melanin pigmentation in the presumptive RPE and its differentiation into neural-retina-like lineages. Comparison of RNA-Seq data from wild type and KO E11.5 embryos demonstrated reduced expression of melanin-related genes and significant overlap with genes known to be dynamically regulated at the optic fissure. ConclusionsThese results demonstrate a critical role of Zfp503 in RPE differentiation and in optic fissure closure.

developmental biology↗