Lucas Guttieres, a graduate student in the Department of Biology and supervised by Mark Q. Martindale, successfully defended his PhD dissertation on July 15th, 2026, and walked in the University of Florida doctoral graduation ceremony on August 7th.
Dr. Guttieres was interested in the emergence of multicellularity that required the evolution of new mechanisms mediating cell adhesion, communication, and coordination. Among the proposed molecular candidates that may have contributed to the transition from unicellularity to multicellularity, the protein β-catenin is of particular interest because of its dual role as a structural component of the cadherin-catenin complex (CCC) and as a transcriptional co-regulator in the canonical Wnt (cWnt) signaling pathway. Although these functions are well-characterized in bilaterian animals, their evolutionary origins remain poorly understood. Early-diverging animal lineages provide a valuable framework for investigating the ancestral functions of β-catenin and the emergence of its interaction networks. In his thesis, Dr. Guttieres focused on the evolutionary history of β-catenin interaction networks in the ctenophore species Mnemiopsis leidyi with a particular focus on its adhesive and nuclear functions.
To address this question, cellular, biochemical, and comparative genomic approaches were combined. Immunolocalization analyses using polyclonal antibodies generated against M. leidyi β-catenin revealed its robust enrichment at sites of cell-cell contact, consistent with an adhesion-associated role, as well as nuclear localization in specific cell populations, suggesting a role in transcriptional regulation. Comparative analyses identified conserved β-catenin interaction motifs in candidate adhesion and transcription-associated proteins. Yeast 2-hybrid assays demonstrated that M. leidyi β-catenin directly interacts with key components of both the CCC (cadherin and 𝛼-catenin) and the cWNT signaling pathway (TCF). The β-catenin-TCF interaction was further validated in living cells using bimolecular fluorescence complementation, while site-directed mutagenesis identified residues contributing to these interactions and revealed both conserved and divergent features of their binding interfaces. Together, these findings indicate that both adhesive and transcription-associated β-catenin interaction networks have potentially deep evolutionary origins and were likely established early in animal evolution. This work advances our understanding of the molecular foundations of multicellularity and provides new insights into the ancestral functions of β-catenin and potential impacts to human health and disease.