Intersectin 2 nucleotide exchange factor regulates Cdc42 activity during Xenopus early development.

Area of Science:

• Developmental Biology
• Cell Biology
• Molecular Biology

Background:

• Intersectin 2 (ITSN2) is a conserved scaffold protein involved in endocytosis and actin cytoskeleton regulation.
• ITSN2 is essential for nervous system function and organism viability.
• The long splice variant of ITSN2 (ITSN2-L) has been identified in mammals.

Purpose of the Study:

• Investigate the role of the ITSN2 long isoform in early Xenopus laevis embryonic development.
• Determine the specific functional domains of ITSN2-L responsible for observed phenotypes.
• Elucidate the molecular mechanisms underlying ITSN2-L-mediated developmental defects.

Main Methods:

• Detection of ITSN2-L transcripts in Xenopus embryos.
• Overexpression of ITSN2-L functional domains in embryos.
• Analysis of phenotypic effects, including actin cytoskeleton alterations and gastrulation failure.
• Investigating the role of Cdc42 GTPase in ITSN2-L-induced phenotypes.

Main Results:

• ITSN2-L transcripts are present in Xenopus embryos from the first cleavage.
• Overexpression of ITSN2-L, particularly its C-terminal extension, causes severe developmental defects like hyperpigmentation and gastrulation failure.
• The DH-PH tandem domain of ITSN2-L is responsible for actin cytoskeleton defects.
• These defects are dependent on Cdc42 activity, as evidenced by rescue experiments with dominant-negative Cdc42.

Conclusions:

• The ITSN2-L exchange factor regulates Cdc42 activity during Xenopus embryonic development.
• Dysregulation of Cdc42 by ITSN2-L leads to actin cytoskeleton abnormalities and developmental failure.
• ITSN2-L plays a significant role in early vertebrate embryonic morphogenesis.