Mouse TonEBP-NFAT5: expression in early development and alternative splicing.

Area of Science:

• Molecular Biology
• Cell Biology
• Developmental Biology

Background:

• Tonicity-responsive enhancer binding protein (TonEBP), also known as nuclear factor of activated T cells family 5, is a DNA-binding protein.
• TonEBP is recognized for its role in cellular responses to hypertonic stress.
• However, its expression and activity in isotonic environments suggest broader biological functions.

Purpose of the Study:

• To investigate the biological role of TonEBP beyond hypertonic stress.
• To clone and characterize mouse TonEBP and compare it to its human counterpart.
• To examine the expression patterns and alternative splicing of TonEBP during development and in adult tissues.

Main Methods:

• Cloning of mouse TonEBP.
• Immunohistochemical analysis of TonEBP expression in developing tissues.
• Analysis of alternative splicing of TonEBP mRNA in various tissues and developmental stages.

Main Results:

• Mouse TonEBP shares 92% amino acid similarity with human TonEBP.
• TonEBP is expressed in embryonic stem cells and throughout fetal development in multiple tissues, including brain, colon, heart, muscle, and eyes.
• Widespread alternative splicing of TonEBP exons 2-4 generates four distinct N-terminal polypeptides, two of which exhibit differential transcriptional activity.

Conclusions:

• The presence of TonEBP mRNA during mouse embryogenesis indicates its function throughout development.
• TonEBP is likely involved in the biology of isotonic adult tissues.
• Alternative splicing of TonEBP contributes to functional diversity, suggesting roles beyond osmotic regulation.