Patient-derived AMOTL1 mutations lead to defective cell migration and tissue development

Area of Science:

• Molecular Biology
• Developmental Biology
• Cell Biology

Background:

• Angiomotin-like 1 (AMOTL1) is crucial for organogenesis and development by regulating cell junctions, polarity, and migration.
• Two hotspot mutations (Arg157 and Pro160) in AMOTL1 are linked to congenital defects in multiple families.
• The pathogenic mechanism of these AMOTL1 mutations remained unclear.

Purpose of the Study:

• To elucidate the molecular and cellular mechanisms underlying congenital defects caused by AMOTL1 mutations.
• To investigate the impact of Arg157 and Pro160 mutations on AMOTL1 protein stability and function.
• To explore the consequences of AMOTL1 mutations in a zebrafish model of embryonic development.

Main Methods:

• Investigated the interaction of AMOTL1 mutants (R157C, P160L) with Tankyrase 1/2 (TNKS1/2) and Ring finger protein 146 (RNF146).
• Assessed the effects of mutations on AMOTL1 poly ADP-ribosylation, ubiquitination, and proteasomal degradation.
• Analyzed the impact of AMOTL1 mutants on cell junction and focal adhesion integrity, and cell migration.
• Examined craniofacial, cardiac, and skeletal muscle development in zebrafish embryos expressing the R157C mutant.

Main Results:

• R157C and P160L AMOTL1 mutants failed to interact with TNKS1/2 and RNF146.
• Mutants were resistant to PARylation, ubiquitination, and proteasomal degradation, leading to cytoplasmic accumulation.
• Accumulated AMOTL1 mutants disrupted cell junctions and focal adhesions, inhibiting cell migration velocity and persistence.
• Expression of R157C mutant in zebrafish caused craniofacial, cardiac, and skeletal muscle defects.

Conclusions:

• AMOTL1 mutations impair Tankyrase binding, leading to protein stabilization and disruption of cellular processes.
• These molecular and cellular defects underlie the observed congenital abnormalities.
• The study clarifies the pathogenic mechanism of AMOTL1 mutations in human development.