We describe the first invertebrate model of attention deficit hyperactivity disorder (ADHD) that reproduces its major features, including hyperactivity, male predominance, marked exacerbation by simple carbohydrates, reversible response to dextroamphetamine, and a "paradoxical response" to stimulants.This model may offer new insight into ADHD pathogenesis and treatment.Furthermore, these findings are of particular interest in light of the recent epidemiological evidence showing that patients with dementia have a high frequency of antecedent ADHD symptoms.

We describe the first invertebrate model of attention deficit hyperactivity disorder (ADHD) that reproduces its major features, including hyperactivity, male predominance, marked exacerbation by simple carbohydrates, reversible response to dextroamphetamine, and a "paradoxical response" to stimulants. This model may offer new insight into ADHD pathogenesis and treatment. Furthermore, these findings are of particular interest in light of the recent epidemiological evidence showing that patients with dementia have a high frequency of antecedent ADHD symptoms.

Mutations in DJ-1/PARK7 (Parkinson protein 7) have been identified as a cause of autosomal-recessive PD (Parkinson's disease) and the antioxidant property of DJ-1 has been shown to be involved in the regulation of mitochondrial function and neuronal cell survival. In the present study, we first found that the DJ-1 transgene mitigated MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)-induced DA (dopamine) neuron cell death and cell loss. We then observed that the protein levels of DJ-1 were significantly decreased, whereas levels of Fis1 [fission 1 (mitochondrial outer membrane) homologue] were noticeably increased in the striatum of MPTP-treated mice. In addition to our identification of RNF5 (RING-finger protein-5) as an E3-ligase for Fis1 ubiquitination, we demonstrated the involvement of the DJ-1/Akt/RNF5 signalling pathway in the regulation of Fis1 proteasomal degradation. In other experiments, we found that Akt1 enhances the mitochondrial translocation and E3-ligase activity of RNF5, leading to Fis1 degradation. Together, the identification of Fis1 degradation by DJ-1 signalling in the regulation of oxidative stress-induced neuronal cell death supplies a novel mechanism of DJ-1 in neuronal protection with the implication of DJ-1 in a potential therapeutic avenue for PD.

BACKGROUND:Notch signaling is a highly conserved pathway in multi-cellular organisms ranging from flies to humans. It controls a variety of developmental processes by stimulating the expression of its target genes in a highly specific manner both spatially and temporally. The diversity, specificity and sensitivity of the Notch signaling output are regulated at distinct levels, particularly at the level of ligand-receptor interactions.METHODOLOGY/PRINCIPAL FINDINGS:Here, we report that the Drosophila gene uninflatable (uif), which encodes a large transmembrane protein with eighteen EGF-like repeats in its extracellular domain, can antagonize the canonical Notch signaling pathway. Overexpression of Uif or ectopic expression of a neomorphic form of Uif, Uif*, causes Notch signaling defects in both the wing and the sensory organ precursors. Further experiments suggest that ectopic expression of Uif* inhibits Notch signaling in cis and acts at a step that is dependent on the extracellular domain of Notch. Our results suggest that Uif can alter the accessibility of the Notch extracellular domain to its ligands during Notch activation.CONCLUSIONS/SIGNIFICANCE:Our study shows that Uif can modulate Notch activity, illustrating the importance of a delicate regulation of this signaling pathway for normal patterning.

Neurodegenerative diseases are characterized by progressive dysfunction and death of neurons in specific areas of the nervous system. Loss of neurons is often associated with multiple stresses such as abnormal aggregation of misfolded proteins, deficiency of protein degradation system, mitochondrial dysfunction and excessive oxidative products. HDAC6 has recently been suggested to be an integral factor that copes with these stresses. In this mini-review, we summarize our current understanding of how HDAC6 promotes inclusion formation, facilitates autophagic degradation of protein aggregates and dysfunctional mitochondria. Finally, the possibility for HDAC6 to be a potential preventional and therapeutical target of some neurodegenerative diseases is put forward.

Neurodegenerative diseases are characterized by progressive dysfunction and death of neurons in specific areas of the nervous system. Loss of neurons is often associated with multiple stresses such as abnormal aggregation of misfolded proteins, deficiency of protein degradation system, mitochondrial dysfunction and excessive oxidative products. HDAC6 has recently been suggested to be an integral factor that copes with these stresses. In this mini-review, we summarize our current understanding of how HDAC6 promotes inclusion formation, facilitates autophagic degradation of protein aggregates and dysfunctional mitochondria. Finally, the possibility for HDAC6 to be a potential preventional and therapeutical target of some neurodegenerative diseases is put forward.

Post-translational modification by the small ubiquitin-related modifier (SUMO) is important for a variety of cellular and developmental processes. However, the precise mechanism(s) that connects sumoylation to specific developmental signaling pathways remains relatively less clear. Here, we show that Smt3 knockdown in Drosophila wing discs causes phenotypes resembling JNK gain of function, including ectopic apoptosis and apoptosis-induced compensatory growth. Smt3 depletion leads to an increased expression of JNK target genes Mmp1 and puckered. We show that, although knockdown of the homeodomain-interacting protein kinase (Hipk) suppresses Smt3 depletion-induced activation of JNK, Hipk overexpression synergistically enhances this type of JNK activation. We further demonstrate that Hipk is sumolylated in vivo, and its nuclear localization is dependent on the sumoylation pathway. Our results thus establish a mechanistic connection between the sumoylation pathway and the JNK pathway through the action of Hipk. We propose that the sumoylation-controlled balance between cytoplasmic and nuclear Hipk plays a crucial role in regulating JNK signaling.

Parkinson's disease (PD) is associated with progressive degeneration of dopaminergic (DA) neurons. We report for the first time that the Drosophila histone deacetylase 6 (dHDAC6) plays a critical role in the protection of DA neurons and the formation of alpha-synuclein inclusions by using a Drosophila PD model constructed by ectopic expression of human alpha-synuclein. Depletion of dHDAC6 significantly enhances the effects caused by ectopic expression of alpha-synuclein, namely, loss of DA neurons, retinal degeneration, and locomotor dysfunction. Expression of alpha-synuclein in the DA neurons leads to fewer inclusions in the brains of dHDAC6 mutant flies than in wild-type flies. Conversely, overexpression of dHDAC6 is able to suppress the alpha-synuclein-induced DA neuron loss and retinal degeneration and promote inclusion formation. Furthermore, mutation of dHDAC6 reinforces the accumulation of oligomers that are suggested to be a toxic form of alpha-synuclein. We propose that alpha-synuclein inclusion formation in the presence of dHDAC6 protects DA neurons from being damaged by oligomers, which may uncover a common mechanism for synucleinopathies.