Modulation of 4HNE-mediated signaling by proline-rich peptides from ovine colostrum.

In previous studies we showed that colostrinin (CLN), a complex of proline-rich polypeptides derived from ovine colostrum, induces mitogenic stimulation, as well as a variety of cytokines in human peripheral blood leukocytes, and possesses antioxidant activity in pheochromocytoma (PC12) cells. In this study we investigated the effects of CLN on 4-hydroxynonenal (4HNE)-mediated adduct formation, generation of reactive oxygen species (ROS), glutathione (GSH) metabolism, and the modification of signal transduction cascade that leads to activation of c-Jun N-terminal kinase (JNK) in PC12 cells. Here we demonstrate that CLN (1) reduced the abundance of 4HNE-protein adducts, as shown by fluorescent microscopy and Western blot analysis; (2) reduced intracellular levels of ROS, as shown by a decrease in 2',7'-dichlorodihydro-fluorescein-mediated fluorescence; (3) inhibited 4HNE-mediated GSH depletion, as determined fluorimetrically; and (4) inhibited 4HNE-induced activation of JNKs. Together, these findings suggest that CLN appears to down-regulate 4HNE-mediated lipid peroxidation and its product-induced signaling that otherwise may lead to pathological changes at the cellular and organ level. These findings also suggest further that CLN could be useful in the treatment of diseases such as Alzheimer's, as well as those in which ROS are implicated in pathogenesis.

Colostrinin-driven neurite outgrowth requires p53 activation in PC12 cells.

1. Colostrinin (CLN) induces maturation and differentiation of murine thymocytes, promotes proliferation of peripheral blood leukocytes, induces immunomodulator cytokines, and ameliorates oxidative stress-mediated activation of c-Jun NH2-terminal kinases. 2. Here we report that upon treatment with CLN, medullary pheochromocytoma (PC12) cells ceased to proliferate and extend neurites. 3. The arrest of CLN-treated PC12 cells in the G1 phase of the cell cycle was due to an increase in the phosphorylation of p53 at serine(15) (p53ser15) and expression of p21WAF1. PC12 cells treated with inhibitory oligonucleotides to p53 lacked p53ser15 and p21WAF1 expression, and did not show morphological changes after CLN exposure. Transfection with inhibitory oligonucleotides to p21WAF1 had no effect on p53 activation; however, cells failed to arrest or extend neurites. An oligonucleotide inhibiting luciferase expression had no effect on CLN-mediated p53 activation, p21WAF1 expression, growth arrest, or neurite outgrowth. 4. We conclude that CLN induces delicate cassettes of signaling pathways common to cell proliferation and differentiation, and mediates activities that are similar to those of hormones and neurotrophins, leading to neurite outgrowth.