Animal secretory endolysosome channel discovery

Area of Science:

• Cell Biology
• Biochemistry
• Zoology

Background:

• Secretory pore-forming proteins (PFPs) are vital across all life forms.
• Aerolysin family PFPs (af-PFPs) and trefoil factors (TFFs) form interaction networks.
• The toad Bombina maxima provides a model for studying these interactions.

Purpose of the Study:

• To investigate the functional interactions between af-PFPs and TFFs in Bombina maxima.
• To characterize the novel βγ-CAT complex and its role in cellular processes.
• To propose the secretory endolysosome channel (SELC) pathway.

Main Methods:

• Studied interactions between Bombina maxima af-PFPs and TFFs.
• Investigated the reversible regulation of BmALP1 by BmALP3.
• Analyzed the function of the βγ-CAT complex in endocytosis and exocytosis.

Main Results:

• BmALP1, an af-PFP, interacts with BmTFF3 to form the active βγ-CAT complex.
• βγ-CAT acts on endocytic pathways, forming pores on endolysosomes and stimulating macropinocytosis.
• βγ-CAT also modulates cell exocytosis, aiding material uptake and barrier function.

Conclusions:

• The βγ-CAT complex represents the first identified secretory endolysosome channel (SELC) protein.
• The proposed SELC pathway plays crucial roles in cell interaction and adaptation.
• The SELC pathway is likely conserved in other organisms.