366B Poster - 04. Stem cells, regeneration and tissue injury
Friday April 08, 2:00 PM - 4:00 PM

Authors:
Mayu Inaba; Matthew Antel

Affiliation: UConn Health, Farmington, CT

Keywords:
b. germline stem cell; j. pairing/transvection

Correlation between strength of pairing of homologous chromosomes and gene expression status has been demonstrated in genome-wide, implicating the functional impact of homolog pairing on local transcriptional activity. Drosophila male germline stem cells (GSCs) constantly divide asymmetrically to produce one GSC and the other daughter as a differentiating gonialblast (GB). GB then enters differentiation program in which stem cell specific genes are quickly downregulated. Here we demonstrate that a change of local pairing status of homologous Stat92E loci is required for downregulation of Stat92E gene during the differentiation. Using Oligopaint fluorescent in situ hybridization (FISH) technique, we found that the interaction between homologous loci of Stat92E is always tight in GSCs and immediately loosened in GBs. When one of the STAT92E loci was absent or relocated on other chromosome, Stat92E did not pair and failed to downregulate. Same defect was observed upon knocking down of pairing factors, suggesting that the pairing is likely required for switching transcriptional status. Moreover, Stat92E enhancer element but not cis-transcription is required for the change of pairing status, indicating that pairing change is not a consequence of transcriptional changes. GSCs are known to inherit pre-existing histones (H3 and H4), while newly synthesized histones are distributed in GBs. When this histone inheritance was compromised, the change of Stat92E pairing did not occur, suggesting that the pairing change is an intrinsically programmed process during the asymmetric stem cell division.​ Taken together, we propose a possibility that the change of local pairing status may be a common process to promote rewriting gene activity status during cell-differentiation.