Structure and evolution of the human SPRR3 gene: implications for function and regulation

Area of Science:

• Molecular biology
• Cell biology
• Genetics

Background:

• Stratum corneum acidic protein 3 (SPRR3) is a key protein in the cornified envelope precursor family.
• SPRR3 expression is specifically observed in oral and esophageal epithelia, correlating with keratinocyte terminal differentiation.

Purpose of the Study:

• To investigate the regulatory elements controlling the differentiation-specific expression of SPRR3.
• To understand the role of the promoter region, including the polypyrimidine tract and other binding sites, in SPRR3 gene regulation.

Main Methods:

• Analysis of the SPRR3 promoter region through mutational analysis.
• Transient transfection assays in normal human keratinocytes to assess gene expression.
• Identification of transcription factor binding sites, including Ets, AP-1 (TRE), and ATF/CRE.

Main Results:

• The polypyrimidine tract in the SPRR3 promoter is essential for its expression.
• Multiple regulatory elements, including an Ets binding site (ESE-1), an AP-1 site (Jun/Fos), and an ATF/CRE site (Jun/Fos, ATF), are involved in differentiation-specific SPRR3 expression.
• Evolutionary repositioning of the SPRR3 Ets binding site impacts its contribution to promoter activity.

Conclusions:

• SPRR3 expression during keratinocyte differentiation is tightly regulated by a combination of cis-regulatory elements in its promoter.
• The identified transcription factor binding sites play critical roles in mediating SPRR3's function in epithelial differentiation.
• Evolutionary dynamics of regulatory elements can significantly influence gene expression patterns.