Dopamine and GPCR-mediated modulation of DN1 clock neurons gates the circadian timing of sleep

The metronome-like circadian regulation of sleep timing must still adapt to an uncertain environment. Recent studies in Drosophila indicate that neuromodulation not only plays a key role in clock neuron synchronization but also affects interactions between the clock network and brain sleep centers. We show here that the targets of neuromodulators, G-Protein Coupled Receptors (GPCRs), are highly enriched in the fly brain circadian clock network. Single cell sequencing indicates that they are not only differentially expressed but also define clock neuron identity. We generated a comprehensive guide library to mutagenize individual GPCRs in specific neurons and verified the strategy with a targeted sequencing approach. Combined with a behavioral screen, the mutagenesis strategy revealed a novel role of dopamine in sleep regulation by identifying two dopamine receptors and a clock neuron subpopulation that gate the timing of sleep.

ALS Cognitive Behavioral Screen-Phone Version (ALS-CBS™-PhV): norms, psychometrics, and diagnostics in an Italian population sample

Background Up to 50% of motor neuron disease (MND) patients show neuropsychological deficits which negatively affect prognosis and care. However, disability-related logistical issues and uneven geographical coverage of healthcare services may prevent MND patients from accessing neuropsychological evaluations. This study thus aimed to standardize for the Italian population the ALS Cognitive Behavioral Screen-Phone Version (ALS-CBS™-PhV), an MND-specific, telephone-based screening for frontotemporal dysfunction. Methods The cognitive section of the ALS-CBS™-PhV, the Italian telephone-based Mini-Mental State Examination (Itel-MMSE), and the Telephone Interview for Cognitive Status (TICS) was administered to 359 healthy individuals (143 males, 216 females; age, 52.7 ± 15.8; education, 13.1 ± 4.4). Norms were derived through equivalent scores. Validity, factorial structure, reliability, diagnostic accuracy, and item difficulty and discrimination were examined. Statistical equivalence between the telephone-based and in-person versions was tested. Results ALS-CBS™-PhV measures were predicted by age and education. The ALS-CBS™-PhV reflected a mono-component structure, converged with Itel-MMSE and TICS scores (rs = .23–.51) and was equivalent to its in-person format (t = .37; p = .72). Good internal (Cronbach’s α = .61), test–retest (ICC = .69), and inter-rater (ICC = .96) reliability was detected. High accuracy was found when tested against both the Itel-MMSE and the TICS (AUC = .82–89). Backward digit span items were the most discriminative. Discussion The ALS-CBS™-PhV is a statistically solid screening test for frontotemporal disorders featuring MND. Its standardization allows for (1) improvements in tele-healthcare for MND patients, (2) epidemiological applications, and (3) effective assessments in decentralized clinical trials. The ALS-CBS™-PhV can be also suitable for assessing bedridden and visually impaired patients with motor disorders.

High-throughput behavioral screen in C. elegans reveals novel Parkinson’s disease drug candidates

We recently linked branched-chain amino acid transferase 1 (BCAT1) with the movement disorder Parkinson’s disease (PD), and found that reduction of C. elegans bcat-1 causes abnormal spasm-like ‘curling’ behavior with age. Here, we report the development of a high-throughput automated curling assay and its application to the discovery of new potential PD therapeutics. Four FDA-approved drugs were identified as candidates for late-in-life intervention, with metformin showing the greatest promise for repurposing to PD.

Glial and neuronal Semaphorin signaling instruct the development of a functional myotopic map for Drosophila walking

Motoneurons developmentally acquire appropriate cellular architectures that ensure connections with postsynaptic muscles and presynaptic neurons. In Drosophila, leg motoneurons are organized as a myotopic map, where their dendritic domains represent the muscle field. Here, we investigate mechanisms underlying development of aspects of this myotopic map, required for walking. A behavioral screen identified roles for Semaphorins (Sema) and Plexins (Plex) in walking behavior. Deciphering this phenotype, we show that PlexA/Sema1a mediates motoneuron axon branching in ways that differ in the proximal femur and distal tibia, based on motoneuronal birth order. Importantly, we show a novel role for glia in positioning dendrites of specific motoneurons; PlexB/Sema2a is required for dendritic positioning of late-born motoneurons but not early-born motoneurons. These findings indicate that communication within motoneurons and between glia and motoneurons, mediated by the combined action of different Plexin/Semaphorin signaling systems, are required for the formation of a functional myotopic map.

Glial and neuronal Semaphorin signaling instruct the development of a functional myotopic map for Drosophila walking

Motoneurons developmentally acquire appropriate cellular architectures that ensure connections with postsynaptic muscles and presynaptic neurons. In Drosophila, leg motoneurons are organized as a myotopic map, where their dendritic domains represent the muscle field. Here we investigate mechanisms underlying development of aspects of this myotopic map, required for walking. A behavioral screen identified roles for Semaphorins (Sema) and Plexins (Plex) in walking behavior. Deciphering this phenotype, we show that PlexA/Sema1a mediates motoneuron axon branching in ways that differ in the proximal femur and distal tibia, based on motoneuronal birth order. Importantly, we show a novel role for glia in positioning dendrites of specific motoneurons; PlexB/Sema2a is required for dendritic positioning of late-born motoneurons but not early-born motoneurons. These findings indicate that communication within motoneurons and between glia and motoneurons, mediated by the combined action of different Plexin/Semaphorin signaling systems, are required for the formation of a functional myotopic map.