Biology subjects

Howell, S.

Publications and source records attributed to Howell, S..

21 records · Page 2Linked to original sources

bioRxiv2019

Btbd6-dependent Plzf recruitment to Cul3 E3 ligase complexes through BTB domain heterodimerization

The Cul3 adaptor Btbd6 plays crucial roles in neural development by driving the ubiquitin-dependent degradation of promyelocytic zinc finger transcription factor (Plzf). Btbd6 has conserved motifs, BTB-BACK-PHR, and by analogy with other BTB-BACK adaptors, might be expected to bind to Cul3 through the BTB-BACK domain, and to substrate through the PHR domain. However, we now present a mode of adaptor-substrate interaction through heterodimerisation between the normally homodimeric BTB domains of Btbd6 and Plzf. This heterodimerization appears to occur through monomer exchange that is detected only at or near physiological concentrations. The Btbd6-Plzf heterodimer thus formed assembles into a ternary complex with Cul3. In addition we show that the BTB and PHR domains of Btbd6 promote localisation in the nucleus and that the BACK domain contains a nuclear export signal. Our findings support a model whereby Btbd6 moves into and out of the nucleus, iteratively sweeping Plzf into the cytoplasm and enabling complex formation with Cul3 that presents Plzf for ubiquitination.\n\nHighlightsO_LIA general mechanism for recruitment of BTB domain-containing substrates by BTBdomain adaptors for the Cul3 E3 ligase complex\nC_LIO_LINuclear export of the Plzf/Btbd6 complex mediated by a NES within the Btbd6 BACK domain\nC_LIO_LICul3-dependent Plzf ubiquitylation through heterodimerisation of BTB domains on adaptor and substrate by monomer exchang\nC_LI

biochemistry↗

bioRxiv2018

Ad-Seq, a genome-wide DNA-adduct profiling assay

SummaryCarcinogens form adducts with the DNA which, when not properly repaired, can lead to mutations and drive oncogenesis. The identity, sequence specificity and mutagenicity of most DNA-adducts is however poorly understood and current molecular assays are limited in their scope and scalability. We present a novel genome-wide DNA adduct sequencing (Ad-Seq) assay to map the location of DNA-adducts at single-nucleotide resolution. Ad-Seq enriches for DNA fragments containing nuclease digestion resistant DNA-adducts. The genomic location of the resulting reads is aggregated in a quantitative profile showing the DNA-adduct sequence context. Ad-Seq is quantitative and confirms known specificity of damages from Ultra-Violet light (di-pyrimidine) and cisplatin (AG and GG di-purines). Furthermore, in cells, Ad-Seq profile can be compared to chromatin segments to show that cisplatin associated adducts are depleted in open and active chromatin regions. The Ad-Seq assay can therefore generate a broad DNA signature of DNA damage and, by comparing to mutagen exposure or downstream mutational profile and signatures, be used to improve our understanding of cancer molecular etiology.

genomics↗

bioRxiv2017

Review of UNAIDS national estimates of men who have sex with men, gay dating application users, and HIV 90-90-90 data

BackgroundAchieving the 90-90-90 is essential to keep people alive and to end AIDS. Men who have sex with men (MSM) often have the least access to HIV services.\n\nPurposeEstimates for key populations are often unavailable, dated or have very wide confidence intervals and more accurate estimates are required.\n\nMethodsWe compared registered users from a major gay dating application (2016) from 29 countries with the latest available (2013-2016) UNAIDS estimates by country. We searched the Internet, PubMed, national surveillance reports, UNAIDS country reports, Presidents Emergency Plan for AIDS Relief (PEPFAR) 2016 and 2017 operational plans, and conference abstracts for the latest nationally representative continua for MSM.\n\nResultsOf comparison countries, only 18 countries had UNAIDS or other MSM population estimates in the public domain. UNAIDS estimates were larger than the gay dating application users in 9 countries, perhaps reflecting incomplete market penetration for the application. The gay dating application users in 9 countries were above the UNAIDS estimates; 8 were over 30% higher and three more than double the reported estimate. Seven partial or complete nationally representative care continua for MSM were published between 2010 and 2016. Among estimated MSM living with HIV, viral suppression varied between 42% (United States) to 99% (Denmark). The quality of the continua methods varied (quality data not shown).\n\nConclusion\"What is not monitored is not done\" and social media has significant promise to improve estimates to ensure that MSM and other vulnerable people living with HIV and their communities are not left behind on the way to ending AIDS.

epidemiology↗