Conserved Cis-Acting Range Extender Element Mediates Extreme Long-Range Enhancer Activity in Mammals.

While most mammalian enhancers regulate their cognate promoters over moderate distances of tens of kilobases (kb), some enhancers act over distances in the megabase range. The sequence features enabling such extreme-distance enhancer-promoter interactions remain elusive. Here, we used in vivo enhancer replacement experiments in mice to show that short- and medium-range enhancers cannot initiate gene expression at extreme-distance range. We uncover a novel conserved cis-acting element, Range EXtender (REX), that confers extreme-distance regulatory activity and is located next to a long-range enhancer of Sall1. The REX element itself has no endogenous enhancer activity. However, addition of the REX to other short- and mid-range enhancers substantially increases their genomic interaction range. In the most extreme example observed, addition of the REX increased the range of an enhancer by an order of magnitude, from its native 71kb to 840kb. The REX element contains highly conserved [C/T]AATTA homeodomain motifs. These motifs are enriched around long-range limb enhancers genome-wide, including the ZRS, a benchmark long-range limb enhancer of Shh. Mutating the [C/T]AATTA motifs within the ZRS does not affect its limb-specific enhancer activity at short range, but selectively abolishes its long-range activity, resulting in severe limb reduction in knock-in mice. In summary, we identify a sequence signature globally associated with long-range enhancer-promoter interactions and describe a prototypical REX element that is necessary and sufficient to confer extreme-distance gene activation by remote enhancers.

Valuable Lessons for Pharmacist PBRNs: Insights and Experiences from Physician PBRN Members.

Practice-based research networks (PBRNs) rely on a cadre of engaged members to participate in research projects. As pharmacist PBRNs increase in number, it is helpful to understand how members of other professions view their own participation in PBRNs and potential collaborative research endeavors with pharmacists. Due to their longer history of PBRN experience, physician PBRN members may have helpful advice for the establishment of pharmacy networks. The objectives of this study were to describe perceptions among a group of physician PBRN members about: Advice for developing a pharmacist PBRN, practice aspects that might benefit from collaborating with pharmacists who are part of a PBRN, and benefits and challenges of PBRN member participation. This study employed qualitative research methods. Semi-structured interviews were conducted with physician members of the Oklahoma Physicians Resource/Research Network, a primary care PBRN. Advice for establishing a pharmacist PBRN included identifying a champion, recruiting a core group, and conducting a needs assessment. Collaborative areas of interest included medication use management, patient education on chronic disease states, and physician education on new therapies. Participation benefits were categorized as personal satisfaction, improvement in practice quality improvement, advancement of specialty, peer interaction and learning, and real-time information and support. These findings offer insight into strategies for developing and sustaining pharmacist PBRNs and may inform pharmacist PBRN initiatives related to development, member recruitment and retention, and interprofessional project planning with physician PBRNs.