A complex RARE is required for the majority of Nedd9 embryonic expression

Area of Science:

• Developmental Biology
• Gene Regulation
• Neuroscience

Background:

• Neural precursor cell expressed, developmentally down-regulated 9 (Nedd9) is a crucial scaffolding protein regulating cell functions.
• Nedd9 plays a vital role in the early embryonic nervous system development.
• A retinoic acid response element (RARE) is present in the Nedd9 gene promoter.

Purpose of the Study:

• To investigate the role of the RARE in the Nedd9 gene promoter in regulating Nedd9 expression during embryonic development.
• To determine the necessity of the RARE for both endogenous and retinoic acid-induced Nedd9 expression patterns.

Main Methods:

• Generation of transgenic mice carrying Nedd9 promoter-reporter gene constructs (Nedd9(RARE)-lacZ and Nedd9(mutRARE)-lacZ).
• Analysis of lacZ expression patterns in transgenic embryos to reflect Nedd9 gene activity.
• Treatment of embryos with all-trans retinoic acid (atRA) to assess ectopic expression responses.

Main Results:

• The 5.2 kb Nedd9 promoter region containing the RARE drives a significant subset of endogenous Nedd9 expression in the developing nervous system.
• Mutating the RARE abolished reporter gene expression, indicating its necessity for basal Nedd9 expression.
• Exposure to atRA induced ectopic Nedd9 expression in Nedd9(RARE)-lacZ embryos, but not in Nedd9(mutRARE)-lacZ embryos.

Conclusions:

• The RARE in the Nedd9 2B promoter is essential for a substantial portion of endogenous Nedd9 expression during early embryonic development.
• This RARE is also critical for mediating ectopic Nedd9 expression in response to all-trans retinoic acid.
• Additional regulatory sequences outside the studied 5.2 kb region are required for the complete Nedd9 expression pattern.