Selective role of the DNA helicase Mcm5 in BMP retrograde signaling during Drosophila neuronal differentiation.

The MCM2-7 complex is a highly conserved hetero-hexameric protein complex, critical for DNA unwinding at the replicative fork during DNA replication. Overexpression or mutation in MCM2-7 genes is linked to and may drive several cancer types in humans. In mice, mutations in MCM2-7 genes result in growth retardation and mortality.

Molecular mechanisms that change synapse number.

Synapses are the functional units of the nervous system, and their number and protein composition undergo changes over a wide time scale. These synaptic changes manifest into differential behavioural outputs and, in turn, changes in the external conditions to the individual may elicit changes in synapses. We review here publications appeared during the last 10 years in which advances on molecular and cellular mechanisms for synapse changes have been reported.

The equilibrium between antagonistic signaling pathways determines the number of synapses in Drosophila.

The number of synapses is a major determinant of behavior and many neural diseases exhibit deviations in that number. However, how signaling pathways control this number is still poorly understood. Using the Drosophila larval neuromuscular junction, we show here a PI3K-dependent pathway for synaptogenesis which is functionally connected with other previously known elements including the Wit receptor, its ligand Gbb, and the MAPkinases cascade.

GSK3β inhibition promotes synaptogenesis in Drosophila and mammalian neurons.

The PI3K-dependent activation of AKT results in the inhibition of GSK3β in most signaling pathways. These kinases regulate multiple neuronal processes including the control of synapse number as shown for Drosophila and rodents. Alzheimer disease's patients exhibit high levels of circulating GSK3β and, consequently, pharmacological strategies based on GSK3β antagonists have been designed.

Presynaptic PI3K activity triggers the formation of glutamate receptors at neuromuscular terminals of Drosophila.

Synapse transmission depends on the precise structural and functional assembly between pre- and postsynaptic elements. This tightly regulated interaction has been thoroughly characterised in vivo in the Drosophila glutamatergic larval neuromuscular junction (NMJ) synapse, a suitable model to explore synapse formation, dynamics and plasticity. Previous findings have demonstrated that presynaptic upregulation of phosphoinositide 3-kinase (PI3K) increases synapse number, generating new functional contacts and eliciting changes in behaviour.