Conserved and Unique Roles of bHLH-PAS Transcription Factors in Insects - From Clock to Hormone Reception

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Developmental Biology

Background:

• bHLH-PAS proteins are crucial transcription factors involved in diverse animal development and physiological processes.
• Nine out of twelve bHLH-PAS proteins have orthologs in both arthropods and vertebrates, regulating functions from organogenesis to circadian rhythms.
• Dysfunctional bHLH-PAS proteins are linked to various pathologies.

Purpose of the Study:

• To compare and contrast the functions of bHLH-PAS proteins in insects and vertebrates.
• To highlight conserved and divergent roles of these master regulators across species.
• To investigate the evolutionary trajectory of bHLH-PAS proteins, including losses and unique adaptations.

Main Methods:

• Phylogenetic analysis of bHLH-PAS protein evolution.
• Comparative functional analysis of orthologous bHLH-PAS proteins between arthropods and vertebrates.
• Review of literature on bHLH-PAS protein regulation and function.

Main Results:

• Many orthologous bHLH-PAS proteins exhibit remarkably conserved functions at the molecular level despite significant evolutionary distance.
• A unique bHLH-PAS protein, acting as a juvenile hormone receptor in invertebrates, has been lost during vertebrate evolution.
• Unlike other bHLH-PAS proteins regulated by small molecules, this juvenile hormone receptor represents an unprecedented case.

Conclusions:

• bHLH-PAS proteins are ancient regulators with conserved roles, but evolutionary pressures have led to lineage-specific losses and functional adaptations.
• The loss of the juvenile hormone receptor in vertebrates underscores the diverse evolutionary paths of hormonal signaling.
• Understanding these conserved and divergent functions is key to deciphering complex biological processes and pathologies.