F XX LF and W XX LF Sequences Mediate the NH 2 -terminal Interaction with the Ligand Binding Domain of the Androgen Receptor

The nuclear receptor superfamily members of eukaryotic transcriptional regulators contain a highly conserved activation function 2 (AF2) in the hormone binding carboxyl-terminal domain and, for some, an additional activation function 1 in the NH(2)-terminal region which is not conserved. Recent biochemical and crystallographic studies revealed the molecular basis of AF2 is hormone-dependent recruitment of LXXLL motif-containing coactivators, including the p160 family, to a hydrophobic cleft in the ligand binding domain. Our previous studies demonstrated that AF2 in the androgen receptor (AR) binds only weakly to LXXLL motif-containing coactivators and instead mediates an androgen-dependent interaction with the AR NH(2)-terminal domain required for its physiological function. Here we demonstrate in a mammalian two-hybrid assay, glutathione S-transferase fusion protein binding studies, and functional assays that two predicted alpha-helical regions that are similar, but functionally distinct from the p160 coactivator interaction sequence, mediate the androgen-dependent, NH(2)- and carboxyl-terminal interaction. FXXLF in the AR NH(2)-terminal domain with the sequence (23)FQNLF(27) mediates interaction with AF2 and is the predominant androgen-dependent interaction site. This FXXLF sequence and a second NH(2)-terminal WXXLF sequence (433)WHTLF(437) interact with different regions of the ligand binding domain to stabilize the hormone-receptor complex and may compete with AF2 recruitment of LXXLL motif-containing coactivators. The results suggest a unique mechanism for AR-mediated transcriptional activation

Intermolecular NH 2 -/Carboxyl-terminal Interactions in Androgen Receptor Dimerization Revealed by Mutations That Cause Androgen Insensitivity

Structural alignment of the human androgen receptor dimer was investigated by introducing steroid binding domain mutations that cause partial or complete androgen insensitivity into fusion proteins containing the full-length androgen receptor or the steroid binding domain. Most of the mutants had unchanged apparent equilibrium androgen binding affinity and increased dissociation rates of [3H]methyltrienolone and required increased dihydrotestosterone concentrations for transcriptional activation. In a 2-hybrid protein interaction assay in mammalian cells, the steroid binding domain interacts with an NH2-terminal-DNA binding domain fragment and with the full-length androgen receptor at physiological androgen concentrations in a dose-dependent manner. However, mutations at Val-889 and Arg-752 disrupt the NH2-/carboxyl-terminal interaction when introduced into the steroid binding domain fragment but not when present in the full-length androgen receptor. The N-C bimolecular interaction reduces the dissociation rate of bound androgen and slows the degradation rate of the carboxyl-terminal steroid binding domain fragment. The results suggest that steroid binding domain residues Val-889 and Arg-752 are critical to the NH2-/carboxyl-terminal interaction and that an intermolecular N-C interaction occurs during receptor dimerization that results in an antiparallel arrangement of androgen receptor monomers

Activation Function 2 in the Human Androgen Receptor Ligand Binding Domain Mediates Interdomain Communication with the NH 2 -terminal Domain

Activation function 2 in the ligand binding domain of nuclear receptors forms a hydrophobic cleft that binds the LXXLL motif of p160 transcriptional coactivators. Here we provide evidence that activation function 2 in the androgen receptor serves as the contact site for the androgen dependent NH(2)- and carboxyl-terminal interaction of the androgen receptor and only weakly interacts with p160 coactivators in an LXXLL-dependent manner. Mutagenesis studies indicate that it is the NH(2)-/carboxyl-terminal interaction that is required by activation function 2 to stabilize helix 12 and slow androgen dissociation critical for androgen receptor activity in vivo. The androgen receptor recruits p160 coactivators through its NH(2)-terminal and DNA binding domains in an LXXLL motif-independent manner. The results suggest a novel function for activation function 2 and a unique mechanism of nuclear receptor transactivation

Indiscriminate Males: Mating Behaviour of a Marine Snail Compromised by a Sexual Conflict?

Background: In promiscuous species, male fitness is expected to increase with repeated matings in an open-ended fashion (thereby increasing number of partners or probability of paternity) whereas female fitness should level out at some optimal number of copulations when direct and indirect benefits still outweigh the costs of courtship and copulation. After this fitness peak, additional copulations would incur female fitness costs and be under opposing selection. Hence, a sexual conflict over mating frequency may evolve in species where females are forced to engage in costly matings. Under such circumstance, if females could avoid male detection, significant fitness benefits from such avoidance strategies would be predicted. Methodology/Principal Findings: Among four Littorina species, one lives at very much higher densities and has a longer mating season than the other three species. Using video records of snail behaviour in a laboratory arena we show that males of the low-density species discriminate among male and female mucous trails, trailing females for copulations. In the high-density species, however, males fail to discriminate between male and female trails, not because males are unable to identify female trails (which we show using heterospecific females), but because females do not, as the other species, add a gender-specific cue to their trail. Conclusions/Significance: We conclude that there is likely a sexual conflict over mating frequency in the high-densit

Tendencies towards DEEP or SURFACE learning for participants taking a large massive open online course (MOOC)

In this report we will describe our first steps in understanding the characteristics of individuals enrolling and completing MOOCs. The learner characteristic we focus on is the deep versus shallow learning dimension. We will use the revised two-factor study process questionnaire of Biggs in our study [1]. To our knowledge, there is no comparable research either reported in the literature or currently under way. Our focus is on Learning How to Learn (LHTL), currently the most heavily subscribed course on the Coursera platform. The last offering of LHTL, completed in January, 2015, attracted just under a quarter million learners. In the fourth and final week of the course, the R-SPQ-2F survey instrument was made available to all students on the LHTL site. Approximately 1,600 students completed the survey. We believe our research to be of interest widely because of the confluence in our research of (a) MOOCs, (b) the deep versus surface learning dimension, and (c) a methodology that can lead to better understanding of MOOCs

Three Years After Rollout: A Report on Systemic Changes in a First-Year Engineering Program

This report focuses on an overview and preliminary results for a project to update the first-year engineering program (FYEP) at with an enrollment base of approximately 1,000 students. We are now three years out from the rollout of an updated FYEP that dates from the fall semester, 2017. The goal we have for this paper is to economically describe at the 10,000-foot level (a) our reasons for the systemic changes we established, (b) the core architecture of our revised FYEP, (c) a selected subset of our preliminary findings and observations regarding our revised FYEP, (d) a special observation concerning the ease of transition from face-to-face operation over to complete internet operation of FYEP while maintaining the integrity of our revised operational model all in the context of a global pandemic (coronavirus), and (e) a thumbnail description of our plans for the future

Sustainable change in a first-year engineering program

This Work in Progress, Research-to-Practice report focuses on an overview of an extensive project to update the First-Year Engineering Program, Michigan Technological University. After three planning years, and multiple pilot course offerings, we rolled out at scale in Fall, 2017. Our core student outcome goals in the revamped first-year program include strengthening the ability for open-ended problem solving, enhanced facility with computational problem solving applied to engineering problems, and increased student growth in traits of self-starting learning and positive attitudes for life-long learning. In this report, we describe both the core components of our revised program and the process we have followed to gain support for our revised first-year program, thus promoting program sustainability. We conclude with a core list of research questions we will pursue beginning in AY 2018-2019