Background: Clusterin is a highly conserved glycoprotein with broad tissue distribution but enigmatic biological functions. Results: Clusterin signals via the lipoprotein receptors ApoER2 and VLDLR and stimulates cell proliferation in subventricular zone explants enabling neuronal outgrowth. Conclusion: Clusterin-mediated signaling is essential for neuronal chain formation in vitro. Significance: Discovery of a novel function of clusterin in neurogenesis.

Background:The control of rapid proliferation of granulosa cells during chicken oocyte growth is unknown. Results: Reelin is expressed in theca cells and triggers disabled-1 phosphorylation in granulosa cells via ApoER2 and the VLDL receptor. Conclusion:The Reelin signaling pathway stimulates granulosa cell proliferation during folliculogenesis. Significance: This work demonstrates a novel function of Reelin.

In contrast to mammals, in the chicken major sites of lipoprotein synthesis and secretion are not only the liver and intestine, but also the kidney and the embryonic yolk sac. Two key components in the assembly of triglyceride-rich lipoproteins are the microsomal triglyceride transfer protein (MTP) and apolipoprotein B (apoB). We have analyzed the expression of MTP in the embryonic liver, small intestine, and kidney, and have studied the expression of MTP in, and the secretion of apoB from, the developing yolk sac (YS). Transcript and protein levels of MTP increase during embryogenesis in YS, liver, kidney, and small intestine, and decrease in YS, embryonic liver, and kidney after hatching. In small intestine, the MTP mRNA level rises sharply during the last trimester of embryo development (after day 15), while MTP protein is detectable only after hatching (day 21). In the YS of 15- and 20-day old embryos, apoB secretion was detected by pulse-chase metabolic radiolabeling experiments and subsequent immunoprecipitation. Taken together, our data reveal the importance of coordinated production of MTP and apoB in chicken tissues capable of secreting triglyceride-rich lipoproteins even before hatching.