Transglutaminase and clusterin induction during normal and abnormal limb development in the mouse

Area of Science:

• Developmental Biology
• Cell Death Research
• Teratology

Background:

• Apoptotic cell death plays a vital role in embryonic pattern formation, particularly in limb development.
• Understanding the molecular mechanisms underlying apoptosis during normal and abnormal limb development is crucial for identifying developmental defects.

Purpose of the Study:

• To investigate the relationship between apoptosis and limb development under normal and teratogen-induced abnormal conditions.
• To examine the expression patterns of tissue transglutaminase and clusterin, proteins linked to apoptosis, during mouse limb development.

Main Methods:

• Mouse limb buds were cultured in vitro and exposed to varying concentrations of 4-hydroperoxycyclophosphamide, a cyclophosphamide analog.
• Apoptotic cells were identified using whole-mount in situ DNA labeling and confocal microscopy.
• Protein expression of tissue transglutaminase and clusterin was assessed via immunohistochemistry and immunogold electron microscopy.

Main Results:

• Teratogen exposure significantly increased the number of apoptotic cells in the interdigital areas of developing mouse limbs.
• Tissue transglutaminase expression increased in response to the teratogen, localized to interdigital areas.
• Clusterin expression was upregulated later, with immunogold labeling indicating its presence in phagocytosed apoptotic bodies within interdigital regions.

Conclusions:

• Abnormal limb development induced by teratogens leads to a marked increase in apoptosis within the interdigital mesenchyme.
• Both tissue transglutaminase and clusterin expression are altered in response to teratogen-induced apoptosis during limb development, suggesting their involvement in regulating cell death pathways.