Prion protein, PrP(C), is a glycoprotein that is expressed on the cell surface beginning with the early stages of embryonic stem cell differentiation. Previously, we showed that ectopic expression of PrP(C) in human embryonic stem cells (hESCs) triggered differentiation toward endodermal, mesodermal, and ectodermal lineages, whereas silencing of PrP(C) suppressed differentiation toward ectodermal but not endodermal or mesodermal lineages. Considering that PrP(C) might be involved in controlling the balance between cells of different lineages, the current study was designed to test whether PrP(C) controls differentiation of hESCs into cells of neuron-, oligodendrocyte-, and astrocyte-committed lineages. PrP(C) was silenced in hESCs cultured under three sets of conditions that were previously shown to induce hESCs differentiation into predominantly neuron-, oligodendrocyte-, and astrocyte-committed lineages. We found that silencing of PrP(C) suppressed differentiation toward all three lineages. Similar results were observed in all three protocols, arguing that the effect of PrP(C) was independent of differentiation conditions employed. Moreover, switching PrP(C) expression during a differentiation time course revealed that silencing PrP(C) expression during the very initial stage that corresponds to embryonic bodies has a more significant impact than silencing at later stages of differentiation. The current work illustrates that PrP(C) controls differentiation of hESCs toward neuron-, oligodendrocyte-, and astrocyte-committed lineages and is likely involved at the stage of uncommitted neural progenitor cells rather than lineage-committed neural progenitors.
Keywords: CNTF, ciliary neurotrophic factor; EBs, embryoid bodies; EFG, epidermal growth factor; ESCs, embryonic stem cells; GFAP, glial fibrillary acidic protein; GRM, glial restrictive medium; Lenti-ShPrPC, lentiviral vector expressing short hairpin RNA against PrPC; Lenti-ShScram, lentiviral vector expressing scrambled shRNA; Lenti-TetR, lentiviral vector expressing tetracycline repressor; MEF-CM, mouse embryonic feeder-conditioned medium; MEFs, mouse embryonic fibroblasts; NDM, neuronal differentiation medium; NIM, neural induction medium; NPM, neural proliferation medium; Olig1, a marker of oligodendrocyte-committed lineages; PrPC, normal, cellular isoform of the prion protein; RA, retinoic acid; Syn, synapsin I; TH, tyrosine hydroxylase; Tet, tetracycline; TetR, tetracycline repressor; bFGF, basic fibroblast growth factor; hES+TetR+ShPrPC, hESCs transfected with Lenti-TetR and Lenti-ShPrPC; hES+TetR+ShScram, hESCs transfected with Lenti-TetR and Lenti-ShScram; hESCs, human ESCs; human embryonic stem cells; neural progenitor cells; neuron-committed lineages; prion protein; stem cell differentiation.