Neurite-promoting factor in conditioned medium from RN22 Schwannoma cultures: bioassay, fractionation, and properties.
On polyornithine (PORN) substrata dissociated 8-day chick embryo ciliary ganglionic neurons will survive if the culture medium is supplemented with Ciliary neuronotrophic Factor. However, neuritic growth will not occur unless the substratum is derivatized with a PORN-bindable Neurite Promoting Factor (PNPF). In this preliminary study we report that soluble PNPF can be (1) assayed by a convenient in vitro system; (2) obtained in relatively large amounts from serum-free media conditioned over RN22 Schwannoma cultures; (3) concentrated by using Amicon XM100 ultrafiltration; and (4) separated from nearly all of the non-active protein by using ion-exchange chromatography. The partially purified PNPF can be concentrated using XM100 and is heat- and protease-sensitive. In the course of these fractionation studies we observed in some cases a concentration-dependent interference with the expression of PNPF activity in the bioassay; we propose graphical methods to permit the simultaneous determination of PNPF and the extent of such interference. Different treatments that affected the interference property did not always affect PNPF activity in a reciprocal manner, leaving open the possibility that the interference with PNPF activity results from reversible alteration of the PNPF molecule, or that there exists a separate interfering agent.
D000818:Animals; D001681:Biological Assay; D001688:Biological Products / Q000302:isolation & purification* / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002642:Chick Embryo; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D005726:Ganglia, Parasympathetic / Q000502:physiology*; D009442:Neurilemmoma / Q000503:physiopathology*; D009474:Neurons / Q000502:physiology*
D001688:Biological Products; D003470:Culture Media