Anna Graf
Pronouns: she/her
Research Mentor(s): Donna Martin
Co-Presenter:
Research Mentor School/College/Department: Pediatrics-Genetics / Medicine
Presentation Date: April 20
Presentation Type: Poster
Session: Session 2 – 11am – 11:50am
Room: League Ballroom
Authors: Anna Graf, Jennifer Skidmore, Jelka Cimerman, Donna Martin
Presenter: 43
Abstract
CHARGE Syndrome is a rare disease named for the phenotypes associated with the disorder. Ear anomalies are the most penetrant feature of CHARGE. CHARGE Syndrome occurs in about 1 in 10,000 live births and in 60-70% of cases, the ATP-dependent chromodomain remodeler CHD7 is affected. We previously generated a mouse model of CHARGE syndrome with a null allele Chd7gt to explore the roles of Chd7 and the genes it regulates in the developing inner ear. Chd7 cooperates with Sox2 as a transcriptional cofactor, and they are coexpressed in the developing otocyst. We generated an allelic series to examine Chd7 and Sox2 haploinsufficiency in the developing otocyst. We dissected otocysts from these embryos at e10.5 and performed RNA sequencing. In comparing Chd7+/+ and Chd7gt/+ tissues, we detected upregulation of Lhx1. Using immunohistochemistry, we identified previously unreported endogenous LHX1 staining in the caudal aspect of e10.5 otocysts. We expanded the allelic series to include Chd7gt/gt;Sox2+/+ otocyst and Chd7+/+;Sox2flox/CreERT otocysts and detected ectopic expression of LHX1 in the ventromedial aspect of Chd7+/+;Sox2+/CreERT, Chd7gt/+;Sox2+/+, Chd7gt/+;Sox2+/CreERT, and Chd7+/+;Sox2flox/CreERT otocysts. The most abundant LHX1 staining was found in the ventromedial Chd7gt/gt;Sox2+/+ otocyst. Therefore, rescue of structural defects in Chd7 mutant ears was attempted using an Lhx1 null allele. Paint filling of Chd7gt/+;Lhx1+/- mutants revealed similar structural defects as observed in Chd7gt/+ mutant ears. Upregulation of Lhx1 in Chd7 mutants and ectopic expression of LHX1 in Chd7 mutant inner ears suggests that Chd7 suppresses Lhx1 in the developing mouse inner ear. The abundance of ectopic LHX1 staining in Chd7gt/gt;Sox2+/+ otocysts compared with Chd7gt/+;Sox2+/+ otocysts suggests that ectopic expression of LHX1 caused by loss of Chd7 is dosage-dependent. In contrast, similar levels of ectopic expression of LHX1 found in Chd7+/+;Sox2+/CreERT and Chd7+/+;Sox2flox/CreERT suggest that ectopic expression of LHX1 caused by loss of Sox2 is dosage-independent. Further studies are needed to determine the mechanism by which Chd7 suppresses Lhx1.
Biomedical Sciences, Interdisciplinary, Natural/Life Sciences
