PREditOR: A synthetic biology approach to removing heterochromatin from cells

It is widely accepted that heterochromatin is necessary to maintain genomic stability. However, direct experimental evidence supporting this is slim. Previous studies using either enzyme inhibitors, gene knockout or knockdown studies all are subject to the caveat that drugs may have off-target effects and enzymes that modify chromatin proteins to support heterochromatin formation may also have numerous other cellular targets as well. Here, we describe PREditOR (protein reading and editing of residues), a synthetic biology approach that allows us to directly remove heterochromatin from cells without either drugs or global interference with gene function. We find that removal of heterochromatin perturbs mitotic progression and causes a dramatic increase in chromosome segregation defects, possibly as a result of interfering with the normal centromeric localization of the chromosomal passenger complex. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10577-016-9539-3) contains supplementary material, which is available to authorized users

Epigenetic engineering shows that a human centromere resists silencing mediated by H3K27me3/K9me3

Centromeres are characterized by the centromere-specific H3 variant CENP-A, which is embedded in chromatin with a pattern characteristic of active transcription that is required for centromere identity. It is unclear how centromeres remain transcriptionally active despite being flanked by repressive pericentric heterochromatin. To further understand centrochromatin’s response to repressive signals, we nucleated a Polycomb-like chromatin state within the centromere of a human artificial chromosome (HAC) by tethering the methyltransferase EZH2. This led to deposition of the H3K27me3 mark and PRC1 repressor binding. Surprisingly, this state did not abolish HAC centromere function or transcription, and this apparent resistance was not observed on a noncentromeric locus, where transcription was silenced. Directly tethering the reader/repressor PRC1 bypassed this resistance, inactivating the centromere. We observed analogous responses when tethering the heterochromatin Editor Suv39h1-methyltransferase domain (centromere resistance) or reader HP1α (centromere inactivation), respectively. Our results reveal that the HAC centromere can resist repressive pathways driven by H3K9me3/H3K27me3 and may help to explain how centromeres are able to resist inactivation by flanking heterochromatin

Teachers' emotional experiences in response to daily events with individual students varying in perceived past disruptive behavior

Students' disruptive behavior during classroom events can elicit strong emotions in teachers and impact teachers' occupational wellbeing. This research was the first to test the proposition that teachers' emotional responses depend not solely on the specific classroom events themselves, but also on the perceived history of disruptive behavior of the student involved. Two complimentary studies examined whether teachers' perceptions of students' past disruptive behavior moderated the link between teachers' valence appraisals (i.e., how positive or negative an event was) and emotions in response to the event (i.e., enjoyment, anger, anxiety, self-, and other-related emotions). It was expected that teachers would be more emotionally reactive to events involving students whom they perceived as more disruptive in the past. Study 1 (N = 218 teachers) examined one teacher-selected relevant event of a workday with an individual student. Study 2 (N = 37 teachers) examined multiple events collected through daily diaries across the school year regarding two target students (N = 77) varying in perceived disruptive behavior. Both studies showed that teachers reacted more emotionally negative to students they perceived as more disruptive in the past compared to similarly appraised events with students perceived as less disruptive. Findings were most consistent for teachers' anger. In addition, Study 1 examined whether teachers' event-related emotions were related to their occupational wellbeing that workday. Teachers' anger was the only emotion associated with both teachers' emotional exhaustion and dedication. Intervention efforts to increase teachers' occupational wellbeing may profit from focusing on specific anger-evoking teacher-student dyads and try changing teachers' underlying judgments and associated emotions about disruptive students

Teachers' emotional experiences in response to daily events with individual students varying in perceived past disruptive behavior

Students' disruptive behavior during classroom events can elicit strong emotions in teachers and impact teachers' occupational wellbeing. This research was the first to test the proposition that teachers' emotional responses depend not solely on the specific classroom events themselves, but also on the perceived history of disruptive behavior of the student involved. Two complimentary studies examined whether teachers' perceptions of students' past disruptive behavior moderated the link between teachers' valence appraisals (i.e., how positive or negative an event was) and emotions in response to the event (i.e., enjoyment, anger, anxiety, self-, and other-related emotions). It was expected that teachers would be more emotionally reactive to events involving students whom they perceived as more disruptive in the past. Study 1 (N = 218 teachers) examined one teacher-selected relevant event of a workday with an individual student. Study 2 (N = 37 teachers) examined multiple events collected through daily diaries across the school year regarding two target students (N = 77) varying in perceived disruptive behavior. Both studies showed that teachers reacted more emotionally negative to students they perceived as more disruptive in the past compared to similarly appraised events with students perceived as less disruptive. Findings were most consistent for teachers' anger. In addition, Study 1 examined whether teachers' event-related emotions were related to their occupational wellbeing that workday. Teachers' anger was the only emotion associated with both teachers' emotional exhaustion and dedication. Intervention efforts to increase teachers' occupational wellbeing may profit from focusing on specific anger-evoking teacher-student dyads and try changing teachers' underlying judgments and associated emotions about disruptive students