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© The Rockefeller University Press, 0021-9525/2003/2/464 $5.00
The Journal of Cell Biology, Volume 160, Number 4, 464-464

Hox signals death for neuronal precursors

Preventing apoptosis (right) enables an NSC (outlined) to make more neurons than usual. Gould/Elsevier

The number of neurons in an adult fly is determined by a death-inducing blast of a homeodomain protein, based on results from Bruno Bello, Frank Hirth, and Alex Gould (National Institute for Medical Research, UK).

When the fly larva hatches, neurons are nearly evenly distributed along the major body axis. But in the adult, they are more numerous in the segments of the thorax than the abdomen, in part because neural stem cells (NSCs) in the thorax divide for a longer period of time. The new article describes "how division is stopped in its tracks and why this happens earlier in the abdomen than in the thorax," says Gould.

His group has found that a pulse of an abdomen-specific Hox transcription factor, called AbdA, in late larval stage NSCs determined the final number of neurons. Rather than signaling exit from the cell cycle, AbdA limited proliferation by inducing cell death through the grim/hid/reaper pathway. Artificial premature expression of AbdA further decreased the number of abdominal neurons by inducing early cell death.

Ectopic expression of thorax-specific Hox genes Antp and Ubx also induced NSC apoptosis. However, these genes were not normally expressed in thoracic NSCs, thus allowing the cells to propagate longer. Gould is now looking for more players in the Hox-induced death pathway, including factors that induce AbdA expression. He is also interested in features of NSCs that make them sensitive to Hox-induced apoptosis, even while many other Hox-expressing cell types are spared.

Reference:

Bello, B., et al. 2003. Neuron. 37:209–219.[CrossRef][Medline]

Nicole LeBrasseur

lebrasn{at}rockefeller.edu

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This Article Full Text (PDF, 1392K) PPT slides of all figures Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by LeBrasseur, N. Search for Related Content PubMed Articles by LeBrasseur, N. Social Bookmarking                            What's this?