Pleiotropic germline PTEN mutations influence gastrulation through dysregulated AKT activation

Area of Science:

• Developmental Biology
• Genetics
• Cancer Research

Background:

• PTEN hamartoma tumor syndrome (PHTS) arises from germline PTEN mutations, leading to diverse clinical features like hamartomas, cancers, and neurodevelopmental disorders.
• The pleiotropic nature of PHTS presents significant patient management challenges.
• The impact of specific PTEN mutations on early embryonic development remains incompletely understood.

Purpose of the Study:

• To investigate the hypothesis that alterations during gastrulation, dependent on the specific mutant PTEN allele, contribute to the pleiotropism observed in PHTS.
• To establish a model system for studying the effects of distinct PHTS-associated PTEN mutations on human embryonic development.

Main Methods:

• Generation of gastruloids from isogenic human induced pluripotent stem cells carrying clinically relevant heterozygous PTEN mutations (PTEN^G132D/WT and PTEN^M134R/WT) and wild-type (PTEN^WT/WT).
• Analysis of gastruloid morphology, gene expression patterns, and signaling pathway activation (e.g., AKT).
• Application of a machine-learning algorithm for morphological classification and assessment of drug response.

Main Results:

• PTEN^G132D/WT gastruloids exhibited axial over-elongation, linked to AKT hyperactivation and Snail (epithelial-to-mesenchymal transition regulator) upregulation.
• Distinct gene expression enrichments in mesoderm and endoderm were observed in PTEN^G132D/WT gastruloids compared to PTEN^M134R/WT and PTEN^WT/WT gastruloids.
• A machine-learning model successfully identified PTEN^G132D/WT gastruloids and predicted morphological reversal upon AKT inhibitor treatment.

Conclusions:

• Mutant PTEN allele-specific alterations during early human development (gastrulation) may correlate with distinct clinical outcomes in PHTS patients.
• This gastruloid model provides a valuable platform for dissecting pathogenic PTEN mutations and for screening potential therapeutic compounds.