Castro-Padovani, T. N. | Search bioRxiv

bioRxiv2023

It All Rolls Downstream: Upstream Control of Physical Activity Regulation

Physical activity is regulated by a variety of genetic molecules. However, the pathways through which those molecules work to regulate activity is largely unknown. The purpose of this study was to gather the known genetic molecules that are associated with activity regulation and define overall upstream regulator pathways through which these molecules work. We conducted a systematic review to gather all available published datasets related to physical activity regulation, standardized the data for genomic location and species, and used this data, in an unbiased manner to create a dataset that was used: (1) to physically map and visualize all identified molecules to homologous chromosome locations and (2) as the dataset for which an Upstream Regulator Analysis (URA) was conducted using Qiagen Ingenuity Pathway Analysis (IPA) software. Our search resulted in 469 genetic molecules (e.g. genomic variant, transcript, protein, micro-RNA) that were split into brain (n=366) and muscle (n=345) sub-groups, which was our attempt to separate differences in central vs peripheral pathways. The brain and muscle data sets had several potential upstream regulators, the top-rated being {beta}-estradiol as a regulator for 19.5% and 21% of the brain and muscle datasets respectively. To our knowledge, {beta}-estradiols identification as a potential regulator, is the first evidence to link the well-known effects of sex hormones on physical activity with genetic regulation of physical activity. There were a variety of potential upstream regulators for the molecules collected in this review, but interestingly, three of the top five for both brain and muscle are nuclear receptor binding ligands; estradiol (estrogen receptor), dexamethasone (glucocorticoid receptor), and tretinoin (retinoic acid receptor), indicating a potential role of nuclear receptors in the regulation of physical activity. Selective nuclear receptor modulation may be an area of interest in future mechanistic studies of the genetic regulation of physical activity.

genetics↗

bioRxiv2022

Gac is a transcriptional repressor of the Lyme disease spirochete's OspC virulence-associated surface protein

The OspC outer-surface lipoprotein is essential for the Lyme disease spirochetes initial phase of vertebrate infection. Bacteria within the midguts of unfed ticks do not express OspC, but produce high levels when ticks begin to ingest blood. Lyme disease spirochetes cease production of OspC within 1-2 weeks of vertebrate infection, and bacteria that fail to downregulate OspC are cleared by host antibodies. Thus, tight regulation of OspC levels is critical for survival of Lyme borreliae, and therefore an attractive target for development of novel treatment strategies. Previous studies determined that a DNA region 5 of the ospC promoter, the ospC operator, is required for control of OspC production. Hypothesizing that the ospC operator may bind a regulatory factor, DNA affinity pulldown was performed, and identified binding by the Gac protein. Gac is encoded by the C-terminal domain of the gyrA open reading frame, from an internal promoter, ribosome-binding site, and initiation codon. Our analyses determined that Gac exhibits a greater affinity for ospC operator and promoter DNAs than for other tested borrelial sequences. In vitro and in vivo analyses demonstrated that Gac is a transcriptional repressor of ospC. These results constitute a substantial advance to our understanding the mechanisms by which the Lyme disease spirochete controls production of OspC. ImportanceBorrelia burgdorferi (sensu lato) requires its surface-exposed OspC protein in order to establish infection of humans and other vertebrate hosts. Bacteria that either do not produce OspC during transmission, or fail to repress OspC after infection is established, are rapidly cleared by the host. Herein, we identified a borrelial protein, Gac, that exhibits preferential affinity to the ospC promoter and 5 adjacent DNA. A combination of biochemical analyses and investigations of genetically-manipulated bacteria demonstrated that Gac is a transcriptional repressor of ospC. This is a substantial advance toward understanding how the Lyme disease spirochete controls production of the essential OspC virulence factor, and identifies a novel target for preventative and curative therapies.

microbiology↗