Investigation of the Molecular Mechanisms of a Novel Finger Protein, Znf179, in Neuronal Differentiation

Znf179 is a member of the RING finger protein family. During embryogenesis, Znf179 is restrictedly expressed in the brain, suggesting a potential role in nervous system development. In our previous study, we show that the expression of Znf179 is upregulated during P19 cell neuronal differentiation. Inhibition of Znf179 expression by RNA interference significantly attenuated neuronal differentiation of P19 cells and a primary culture of cerebellar granule cells. Using a microarray approach and subsequent functional annotation analysis, we identified the differentially expressed genes in Znf179 knockdown cells and found that several genes are involved in development, cellular growth, and cell cycle control. Flow cytometric analyses revealed that the population of G0/G1 cells decreased in Znf179 knockdown cells. In agreement with the flow cytometric data, we found the protein level of p27, a critical negative regulatory protein of the G1/S transition, was significantly diminished by Znf179 knockdown. Moreover, in Znf179 knockdown cells, p35, a neuronal-specific Cdk5 activator, which is known to activate Cdk5 to phosphorylate and stabilize p27, also decreased. Collectively, our results suggest that induction of the Znf179 gene may be associated with p35 expression and p27 protein accumulation, which leads to cell cycle arrest in the G0/G1 phase, and is critical for neuronal differentiation of P19 cells. In the further studies, we will investigate the molecular mechanisms by which Znf179 regulates p35 expression. Moreover, we have generated Znf179 knockout mice. We will use the knockout mice to investigate the physiological role of Znf179.