Figure 6

Model of factors regulating C . elegans vitellogenesis. In intestinal cells of adult hermaphrodites (left), vit genes are transcribed and translated into yolk proteins (YP), which function as ApoB-100-like lipid transport proteins for mobilization of nutrients from the intestine to the oocytes. After synthesis in the intestine, YP are exported into the pseudocoelomic space and taken up by oocytes in the gonad (right). daf-16 activity appears to affect vitellogenesis through two separable pathways. In intestinal cells, daf-16 activity represses YP production at a posttranscriptional level. In addition, increased daf-16 activity in daf-2(e1370) hermaphrodites suppresses a germline-dependent signal that stimulates vit-2 mRNA production. The daf-16-dependent regulation of germline-dependent vit-2 mRNA stimulation may reflect daf-2 and daf-16 regulation of germline proliferation [22].