During neurogenesis, neural patterning is a critical step during which neural progenitor cells (NPCs) differentiate into neurons with distinct functions. However, the molecular determinants that regulate neural patterning remain poorly understood. Here, we optimized the "dual-SMAD inhibition" method to specifically promote differentiation of human pluripotent stem cells (hPSCs) into forebrain and hindbrain NPCs along the rostral-caudal (R-C) axes. We report that neural patterning determination occurs at the very early stage in this differentiation. Undifferentiated hPSCs expressed basal levels of the transcription factor orthodenticle homeobox 2 (OTX2) that dominantly drove hPSCs into the "default" rostral fate at the beginning of differentiation. Inhibition of glycogen synthase kinase 3β (GSK3β) through CHIR99021 (CHIR) application sustained transient expression of the transcription factor NANOG at early differentiation stages through Wnt signaling. Wnt signaling and NANOG antagonized OTX2 and in the later stages of differentiation, switched the default rostral cell fate to the caudal one. Our findings have uncovered a mutual antagonism between NANOG and OTX2 underlying cell fate decisions during neural patterning, critical for the regulation of early neural development in humans.The embryonic neurodevelopment is a spatiotemporally regulated process, during which http://www.jbc.org/ Downloaded from 2 distinct cell fates are progressively restricted based on spatial regions (1, 2). At early stage of neurogenesis, the specified neural ectoderm divides into functionally distinct cell fates along the anterior-posterior (A-P) and dorsal-ventral (D-V) axes (3). This neural patterning process is a critical step to specify different neural precursors such as forebrain, midbrain, hindbrain and spinal cord. It has been known that the neural patterning is induced by the temporal and special morphogen gradients along the A-P and D-V axes (4, 5). These morphogens, including BMPs, WNTs, FGFs, RA and SHH (sonic hedgehog), coordinate and form gradients to specify regionally transcriptional program and distinct neural progenitors (6-10). However, the precise timing and mechanisms underlying morphogeninduced neuraxial patterning has not been fully elucidated in mammals, especially in human.Human pluripotent stem cells (hPSCs), including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSC) could differentiate into neuroepithelial cells , regionally specified neural precursor cells (11-16), thus provides a valuable model to investigate molecular determinants on neural patterning in human background. The mostly used method to induce neural differentiation in hPSCs is through suppression of both TGFβ and BMP signaling (17,18). Dual-inhibition of SMAD-dependent TGF-β and BMP signaling by their inhibitors (SB431542 and Noggin), or SB431542 and Dorsomorphin can efficiently trigger hPSCs differentiation into NPCs (19-21). Dual-SMAD inhibition triggered NPCs are believed to be more close to the anterior forebrai...