A high throughput embryonic stem cell screen identifies Oct-2 as a bifunctional regulator of neuronal differentiation

Abstract

Neuronal differentiation is a complex process that involves a plethora of regulatory steps. To identify transcription factors that influence neuronal differentiation we developed a high throughput screen using embryonic stem (ES) cells. Seven-hundred human transcription factor clones were stably introduced into mouse ES (mES) cells and screened for their ability to induce neuronal differentiation of mES cells. Twenty-four factors that are capable of inducing neuronal differentiation were identified, including four known effectors of neuronal differentiation, 11 factors with limited evidence of involvement in regulating neuronal differentiation, and nine novel factors. One transcription factor, Oct-2, was studied in detail and found to be a bifunctional regulator: It can either repress or induce neuronal differentiation, depending on the particular isoform. Ectopic expression experiments demonstrate that isoform Oct-2.4 represses neuronal differentiation, whereas Oct-2.2 activates neuron formation. Consistent with a role in neuronal differentiation, Oct-2.2 expression is induced during differentiation, and cells depleted of Oct-2 and its homolog Oct-1 have a reduced capacity to differentiate into neurons. Our results reveal a number of transcription factors potentially important for mammalian neuronal differentiation, and indicate that Oct-2 may serve as a binary switch to repress differentiation in precursor cells and induce neuronal differentiation later during neuronal development.[Keywords: Oct-2; neuronal; embryonic stem cell; differentiation; high throughput] Supplemental material is available at http://www.genesdev.org. Neuronal development and differentiation are complex processes that involve extracellular factors, local niche, and intracellular factors. Much is known about extracellular factors that mediate neural induction. For example, inhibition of bone morphogenetic protein (BMP) by chordin, noggin (Sasai et al. 1995;Zimmerman et al. 1996), and follistatin (Hemmati-Brivanlou et al. 1994;Fainsod et al. 1997) (Kageyama et al. 2008). In spite of the large number of transcription factors implicated in neuronal development and differentiation, few systematic studies of these regulators have been performed, and thus it is likely that many other transcription factors regulate neuronal differentiation.The complete sequencing of the human genome offers new approaches to systematically identify components important for neuronal differentiation. Gray et al. (2004) examined the expression of most mouse transcription factors using in situ hybridization, and found that at least 20% of known transcription factors have spatially restricted expression patterns in developing mouse brains. While this study provided a wealth of information on the potential involvement of factors in neurogenesis, it lacked any functional information. In principle, another approach that could be developed is to inactivate transcription factors on a large scale; however, for many Cold Spring Harbor Laboratory Press on May 11, 2018 -Publis...

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