Table 1. Tip60 induced defects on axonal growth and/or PDF expression in Drosophila sLNv affects sleep.

Mutant Phenotype
Genotype	Axon growth	Effect on PDF	Sleep Defects
Tip60HAT mut	Retracted	Partial loss	Yes
APP; Tip60HAT mut	Severely retracted	Complete loss	Yes
Tip60OE	No effect	Elevated	Yes
APP; Tip60OE	Overelaborated	Elevated	No

sLNv directed expression of HAT defective mutant Tip60 (Tip60^{HAT mut}) causes retraction of axons and moderate decrease in PDF expression. These defects are exacerbated in flies that co-express the Tip60 HAT mutant with APP (APP; Tip60^{HAT mut}) resulting in much shorter axons and complete loss of Pdf in sLNv. Sleep defects were observed under both these conditions and consisted of disrupted night sleep and daytime sleepiness. Night sleep was disrupted in flies overexpressing wild type Tip60 (Tip60^OE) that also exhibited elevated levels of PDF in sLNv. Overexpression of Tip60 with APP (APP; Tip60^OE) also induces sLNv PDF levels, however, without any marked effect on sleep, suggesting the induction of compensatory sleep inducing neural signals in these flies. The overelaborated sLNv axon terminals in the protocerebrum in the APP, Tip60OE flies could play a role in transducing such sleep promoting signals.