Search bioRxiv⌕ Search

Biology subjects

Hayward, B.

Publications and source records attributed to Hayward, B..

2 recordsLinked to original sources
bioRxiv2024

MSH2 is not required for either maintenance of DNA methylation or repeat contraction at the FMR1 locus in fragile X syndrome

BackgroundRepeat-induced epigenetic changes are observed in many repeat expansion disorders (REDs). These changes result in transcriptional deficits and/or silencing of the associated gene. MSH2, a mismatch repair protein that is required for repeat expansion in the REDs, has been implicated in the maintenance of DNA methylation seen in the region surrounding expanded CTG repeats at the DMPK locus in myotonic dystrophy type 1 (DM1). Here, we investigated the role of MSH2 in aberrant DNA methylation in two additional REDs, fragile X syndrome (FXS) that is caused by a CGG repeat expansion in the 5 untranslated region (UTR) of the fragile X messenger ribonucleoprotein 1 (FMR1) gene, and Friedreichs ataxia (FRDA) that is caused by GAA repeat expansion in intron 1 of the frataxin (FXN) gene. ResultsIn contrast to what is seen at the DMPK locus in DM1, loss of MSH2 did not decrease DNA methylation at the FMR1 promoter in FXS embryonic stem cells (ESCs) or increase FMR1 transcription. This difference was not due to the differences in the CpG density of the two loci as a decrease in DNA methylation was also not observed in a less CpG dense region upstream of the expanded GAA repeats in the FXN gene in MSH2 null induced pluripotent stem cells (iPSCs) derived from FRDA patient fibroblasts. Surprisingly given previous reports, we found that FMR1 reactivation was associated with a high frequency of MSH2- independent repeat contractions that resulted a permanent loss of DNA methylation. ConclusionsOur results suggest that there are mechanistic differences in the way that DNA methylation is maintained in the vicinity of expanded repeats among different REDs even though they share a similar mechanism of repeat expansion. The high frequency of transcription- induced MSH2-independent contractions we have observed may contribute to the mosaicism that is frequently seen in carriers of FMR1 alleles with expanded CGG-repeat tracts. Given the recent interest in the therapeutic use of transcription-driven repeat contractions, our data may have interesting mechanistic, prognostic, and therapeutic implications. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=118 SRC="FIGDIR/small/629815v1_ufig1.gif" ALT="Figure 1000"> View larger version (20K): org.highwire.dtl.DTLVardef@1a6a59aorg.highwire.dtl.DTLVardef@1c25fdborg.highwire.dtl.DTLVardef@23394eorg.highwire.dtl.DTLVardef@876445_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗
bioRxiv2019

Comparative palatability of orally disintegrating tablets (ODTs) of Praziquantel (L-PZQ and Rac-PZQ) versus current PZQ tablet in African children: a randomized, single-blind, crossover study

BackgroundPraziquantel (PZQ) is currently the only recommended drug for infection and disease caused by the species of schistosome infecting humans; however, the current tablet formulation is not suitable for preschool age children mainly due to its bitterness and the size of the tablet. We assessed the palatability of two new orally disintegrating tablet (ODT) formulations of PZQ.\n\nMethodsThis randomized, single-blind, crossover, swill-and-spit palatability study (NCT02315352) was carried out at a single school in Tanzania in children aged 6-11 years old, irrespective of schistosomiasis infection. Children were stratified according to age group (6-8 years or 9-11 years) and gender, then randomized to receive each formulation in a pre-specified sequence. Over 2 days, the children assessed the palatability of levo-Praziquantel (L-PZQ) ODT 150 mg and Racemate Praziquantel (Rac-PZQ) ODT 150 mg disintegrated in the mouth without water on the first day, and L-PZQ and Rac-PZQ dispersed in water and the currently available PZQ 600 mg formulation (PZQ-Cesol(R)) crushed and dispersed in water on the second day. The palatability of each formulation was rated using a 100 mm visual analogue scale (VAS) incorporating a 5-point hedonic scale, immediately after spitting out the test product (VASt=0 primary outcome) and after 2-5 minutes (VASt=2-5).\n\nFindingsIn total, 48 children took part in the assessment. Overall, there was no reported difference in the VASt=0 between the two ODT formulations (p=0.106) without water. Higher VASt=0 and VASt=2-5 scores were reported for L-PZQ ODT compared with Rac-PZQ ODT in older children (p=0.046 and p=0.026, respectively). The VASt=0 and VASt=2-5 were higher for both ODT formulations compared with the current formulation (p<0.001 for both time points). No serious adverse events were reported.\n\nInterpretationThe new paediatric-friendly formulations dispersed in water were both found to be more palatable than the existing formulation of PZQ. There may be gender and age effects on the assessment of palatability.\n\nFundingThis study was funded by Merck KGaA, Darmstadt, Germany and the Global Health Innovative Technology (GHIT) Fund (Grant nos. 2013-212).\n\nAuthor summarySchistosomiasis or Bilharzia is among top debilitating parasitic diseases in endemic developing countries. It presents in two forms of either urinary or intestinal form. The diseases mode of transmission is waterborne through contact with infested water. The main group being affected in developing countries are women and children due to their frequent contact with water. WHO introduced mass drug administration program whereby drugs are distributed in endemic communities to cut off the transmission of NTDs schistosomiasis included.\n\nPraziquantel is the sole drug for treatment of all forms of Schistosomiasis currently and it has still been proven to be highly efficacious. Preventive chemotherapy program of WHO uses the same drug as a prophylactic tool to control the disease.\n\nThe biggest challenge for this drug is its availability as a 600mg tablet with a slightly bigger size and unpleasant taste, especially for younger children. This makes uneasy administering the correct dosage of drug to school children while making preschoolers totally neglected.\n\nThis study was done as swill and spit exercise (drug was not ingested) to assess the new orally disintegrating isomers of Praziquantel, L-PZQ and Rac-PZQ which have been prepared as a 150mg tablet and improved taste as compared to the existing Praziquantel formulation. Findings from 48 African children showed that both new formulations are more palatable to younger children as compared to the existing Praziquantel formulation.\n\nThese results provide evidence for further evaluation of the clinical efficacy and tolerability of the newer formulations towards the introduction of paediatric friendly Praziquantel tablets for Schistosomiasis treatment.

epidemiology↗