Mis-Expression of a Cranial Neural Crest Cell-Specific Gene Program in Cardiac Neural Crest Cells Modulates HAND...

Area of Science:

• Developmental biology
• Molecular genetics
• Cardiovascular research

Background:

• Congenital heart defects (CHDs) are a major cause of morbidity and mortality.
• Aberrant development of the cardiac outflow tract (OFT) and cardiac neural crest cells (NCCs) contribute significantly to CHDs.
• Gene regulatory networks governing cardiac NCC specification are not fully understood.

Purpose of the Study:

• To investigate the role of transcription factors DLX5 and DLX6 in differentiating cranial and cardiac NCCs.
• To understand the differential regulation of the Hand1 enhancer by DLX5/DLX6 in cranial versus cardiac NCCs.
• To explore how initial NCC specification influences gene regulatory control.

Main Methods:

• Generation of a conditionally active transgene for ectopic DLX5 expression in developing mouse embryos.
• Utilized a Cre-recombinase-dependent system for spatiotemporal control of DLX5 expression.
• Assessed reporter gene expression (Hand1^OFT-lacZ) and NCC cell death in response to ectopic DLX5.

Main Results:

• Ectopic DLX5 expression repressed cranial NCC Hand1^OFT-lacZ reporter expression more effectively than cardiac NCC reporter expression.
• Ectopic DLX5 induced significant NCC cell death in cranial pharyngeal arches but minimal cell death in cardiac NCC populations.
• Demonstrated differential sensitivity of cranial and cardiac NCCs to DLX5-mediated transcriptional repression.

Conclusions:

• Transcription factor DLX5 plays a critical role in repressing Hand1 expression in cranial NCCs.
• Differential regulation by DLX5 contributes to the distinct developmental outcomes of cranial and cardiac NCCs.
• Initial specification of NCCs at the dorsal neural tube influences subsequent gene regulatory programs and cell fate.