Development

Jelly Belly

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Science  16 Nov 2001:
Vol. 294, Issue 5546, pp. 1419
DOI: 10.1126/science.294.5546.1419b

The process by which early embryonic germ tissues give rise to multiple organs and tissues involves the coordination of cell type determination and localization. In Drosophila, early mesoderm gives rise to heart, somatic, and muscle precursors.

Weiss et al. report that Jelly belly (Jeb), a secreted protein containing an LDL receptor repeat motif, acts as an extracellular signaling molecule that regulates visceral mesoderm development. In the absence of functional Jeb, no differentiated mesoderm was detected, although other components of the mesoderm appeared normal. Although Jeb is synthesized in somatic muscle mesoderm precursor cells, it is internalized by adjacent visceral mesoderm precusor cells. A block in endocytosis reduced the presence of Jeb in target visceral mesoderm, suggesting that a receptor may be involved in the uptake of secreted Jeb by target cells. Jeb was initially identified as a target of the Tin homeobox transcription factor, and the cell migration defects observed in the visceral mesoderm of Jeb mutants indicate that this signaling molecule may convey differentiation and positional information to a specific population of mesoderm precursor cells.—LC

Cell107, 387 (2001).

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