Transcription Factor Brn-3b Overexpression Enhances Neurite Outgrowth in PC12 Cells Under Condition of Hypoxia.

Abstract

Transcription factor Brn-3b plays a key role in retinal ganglion cell differentiation, survival, and axon outgrowth during development. However, the precise role of Brn-3b in the normal adult retina as well as during neurodegeneration is unclear. In the current study, the effect of overexpression of Brn-3b was assessed in vitro, in PC12 cells under conditions of normoxia and hypoxia. Immunoblot analysis showed that overexpression of Brn-3b in PC12 cells as well as 661W cells produced significant increase in the growth cone marker, growth-associated protein-43 (GAP-43), and acetylated-tubulin (ac-TUBA). In addition, an increased immunostaining for GAP-43 and ac-TUBA was observed in PC12 cells overexpressing Brn-3b, which was accompanied by a marked increase in neurite outgrowth, compared to PC12 cells overexpressing the empty vector. In separate experiments, one set of PC12 cells transfected either with a Brn-3b expression vector or an empty vector was subjected to conditions of hypoxia for 2 h, while another set of similarly transfected PC12 cells was maintained in normoxic conditions. It was found that the upregulation of GAP-43 and ac-TUBA in PC12 cells overexpressing Brn-3b under conditions of normoxia was sustained under conditions of hypoxia. Immunocytochemical analysis revealed not only an upregulation of GAP-43 and ac-TUBA, but also increased neurite outgrowth in PC12 cells transfected with Brn-3b as compared to PC12 cells transfected with empty vector in both normoxia and hypoxia. The findings have implications for a potential role of Brn-3b in neurodegenerative diseases in which hypoxia/ischemia contribute to pathophysiology of the disease.

• Authors: Nitasha R Phatak, Dorota L Stankowska, Raghu R Krishnamoorthy
• Journal: Cellular and molecular neurobiology (Cell Mol Neurobiol) Vol. 35 Issue 6 Pg. 769-83 (Aug 2015) ISSN: 1573-6830 [Electronic] United States
• PMID: 25786379 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Transcription Factor Brn-3B
• Oxygen

Topics

• Animals
• Axons (drug effects, metabolism, physiology)
• Cell Culture Techniques
• Cell Differentiation (drug effects, genetics)
• Cell Hypoxia (genetics)
• Cells, Cultured
• Mice
• Neurites (drug effects, metabolism, physiology)
• Neurogenesis (drug effects, genetics)
• Oxygen (pharmacology)
• PC12 Cells
• Rats
• Transcription Factor Brn-3B (genetics)
• Up-Regulation (genetics)