Elsevier

Neuroscience

Volume 143, Issue 2, 1 December 2006, Pages 501-514
Neuroscience

Cellular neuroscience
SRY-box containing gene 11 (Sox11) transcription factor is required for neuron survival and neurite growth

https://doi.org/10.1016/j.neuroscience.2006.09.010Get rights and content

Abstract

The transcription factor Sox11 is expressed at high levels in developing sensory neurons and injured adult neurons but little is known about its transcriptional targets and function. In this study we examined the role of Sox11 using Neuro2a neuroblastoma cells and cultured mouse dorsal root ganglia (DRG) neurons. Results show Sox11 has an essential role in regulation of neuron survival and neurite outgrowth in Neuro2a cells and primary sensory neurons. Neuro2a cells increase expression of Sox11 as they differentiate in culture. Following addition of 20 μM retinoic acid (RA), a stimulus for differentiation that enhances neurite growth and differentiation, Sox11 level rises. RNAi-mediated knockdown of Sox11 in RA-differentiated Neuro2a cells caused a decrease in neurite growth and an increase in the percent of apoptotic cells. RNA expression analysis showed that Sox11 knockdown modulated the level of mRNAs encoding several genes related to cell survival and death. Further validation in the Neuro2a model showed Sox11 knockdown increased expression of the pro-apoptotic gene BNIP3 (BclII interacting protein 1 NIP3) and decreased expression of the anti-apoptotic gene TANK (TNF receptor-associated factor family member-associated NFκB activator). Cultured primary DRG neurons also express Sox11 and treatment with Sox11 small interfering RNA (siRNA) caused a significant decrease in neurite growth and branching and a decrease in mRNA encoding actin-related protein complex 3 (Arpc3), an actin organizing protein that may be involved in axon growth. The percent of apoptotic neurons also increased in cultures of DRG neurons treated with Sox11 siRNA. Similar to Neuro2a cells, a decrease in TANK gene expression occurred, suggesting at least some overlap in Sox11 transcriptional targets in Neuro2a and DRG neurons. These data are consistent with a central role for Sox11 in regulating events that promote neurite growth and neuron survival.

Section snippets

Cell culture

The mouse neuroblastoma cell line Neuro2a (ATCC clone number CCL-131, Manassas, VA, USA) (Olmsted et al., 1970) was maintained in Eagle’s minimal essential medium (MEM) containing 10% fetal bovine serum (MEMS) and 1% penicillin/streptomycin in an incubator set at 37 °C and 5% CO2. Cells used were passaged no more than three times. For all experiments, cells were plated into 12- or 24-well plates at a concentration of 10,000 and 5000 cells/well, respectively, or plated into two- or four-well

Sox11 is expressed in Neuro2a neuroblastoma cells

Neuro2a cells provide an excellent model system to study transcriptional regulation of neuronal differentiation. They are easily propagated, they can be stimulated to differentiate by addition of 20 μM RA and upon differentiation stop dividing and extend neurites (Shea et al 1985, Sajithlal et al 2002, Munch et al 2003, Noguchi et al 2003). Under culture conditions without RA, Neuro2a cells appear as amoeboid neuroblasts that begin to extend neurites after 1–3 days in culture. To assess if

Discussion

The identification of Sox11 as a developmentally expressed transcription factor that is rapidly elevated in adult neurons following axotomy prompted us to explore how this transcription factor regulates gene expression in injured adult sensory neurons of the DRG. To begin this analysis we used primary cultures of DRG neurons and the neuronal cell line Neuro2a to determine if Sox11 affects cell survival and neurite extension and if so, what transcriptional targets Sox11 might regulate. Using the

Acknowledgments

We thank Beth Knapick for excellent technical assistance, Dr. Carol Troy (Columbia University, NY, USA) for generously sharing her expertise in using the Penetratin peptide for siRNA delivery and Dr. Brian Davis for helpful discussion and advice. This research was supported by grants from the NINDS NS33730 (K.M.A.) and T32NS007433 (M.P.J.).

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