[
Cell,
2007]
Several extracellular factors, including Wnt proteins, have been reported to induce synapse formation. In this issue, Klassen and Shen (2007) report that Wnt proteins can also act as antisynaptogenic signals to prevent synapse formation in certain parts of the worm Caenorhabditis elegans. The differential response of axon populations to local Wnt proteins may contribute to the patterning of synaptic connections.
[
Worm,
2016]
The hypoxic response is a well-studied and highly conserved biological response to low oxygen availability. First described more than 20 y ago, the traditional model for this response is that declining oxygen levels lead to stabilization of hypoxia-inducible transcription factors (HIFs), which then bind to hypoxia responsive elements (HREs) in target genes to mediate the transcriptional changes collectively known as the hypoxic response.(1,2) Recent work in C. elegans has forced a re-evaluation of this model by indicating that the worm HIF (HIF-1) can mediate effects in a cell non-autonomous fashion and, in at least one case, increase expression of an intestinal hypoxic response target gene in cells lacking HIF-1.