• Coffin-Siris syndrome

This report describes a Drosophila model using the fly gene osa to model an intellectual developmental disorder(s) caused by disruption of SWI/SNF complexes; see the general report for Coffin-Siris syndrome (FBhh0001088). Dmel\osa encodes a component of some SWI/SNF complexes; these complexes regulate transcription via chromatin remodeling. The osa protein is not a core member of this family of complexes: it encodes a component of the canonical complex, designated BAP in flies (analogous to BAF in human). Classical amorphic and hypomorphic alleles, RNAi-targeting constructs, and alleles caused by insertional mutagenesis have been generated for osa.

There are two genes orthologous to Dmel\osa in human, ARID1A and ARID1B, both of which are implicated in subtypes of Coffin-Siris syndrome (see FBhh0001090 and FBhh0001091). Neither human gene has been introduced into flies.

Animals homozygous for a loss-of-function mutation of osa die during the embryonic stage. RNAi-targeted knockdown of osa in the mushroom body (a brain region associated with learning and memory) causes male flies not to reduce courtship attempts after being rejected by a female, a measure of memory formation in flies. Impairment of long-term memory, but not short-term memory, is observed. Defects in mushroom body morphology are observed, including reduced survival of MBγ axons during ageing. Many physical and genetic interactions have been reported for Dmel\osa; see below and in the osa gene report.

[updated Jul. 2019 by FlyBase; FBrf0222196]