Calreticulin binding and other biological activities of survival peptide Y-P30 including effects of systemic treatment of rats

Neuron survival-promoting peptide Y-P30, purified from oxidatively stressed neural cell lines, inhibits the appearance of microglia and rescues neuron s 1 week after direct application to lesions of the rat cerebral cortex (7) . Y-P30 affinity matrices treated with solubilized membranes from a variety of cell lines including human neuroblastoma SY5Y, mouse hippocampal cells HN 33.1, and human promonocytes HL-60, as well as with cerebral cortex tiss ue from both humans and rats, showed highly specific binding to calreticuli n, a ubiquitous calcium binding protein that may be critical for integrin f unction. Treatment of cultures with 0.1 nM Y-P30 stabilized all these cell types whether differentiated or not, while 1 mu M peptide also inhibited th e morphological differentiation of the HL-60 cells into macrophages. Wester n analysis of the medium of SY5Y cell cultures suggested Y-P30-stimulated r elease of calreticulin, a result consistent with its other biological activ ities. Likewise, single dose systemic application of Y-P30 in unoperated ra ts and in rats with cerebral cortex lesions produced significant reductions in cerebral cortex membrane-associated calreticulin. Both direct and intra venous treatment with peptide also reduced cortical neuron atrophy 4 days a fter these lesions but only direct application consistently inhibited the a ppearance of ED-1(+) monocyte derivatives. We suggest that in vitro and in vivo mechanisms of Y-P30 effects are similar and involve the targeting of c alreticulin. The results also suggest that some of these activities are app arent in the cerebral cortex after systemic application of this peptide. (C ) 2000 Academic Press.