The C. elegans TspanC8 tetraspanin TSP-14 exhibits isoform-specific localization and function.

Area of Science:

• Molecular Biology
• Developmental Biology
• Cell Biology

Background:

• Tetraspanins are conserved transmembrane proteins with poorly understood in vivo functions.
• The TspanC8 subfamily, including TSP-12 and TSP-14 in C. elegans, plays roles in signaling pathways.
• TSP-14 exists as two isoforms, TSP-14A and TSP-14B, differing in N-terminal length.

Purpose of the Study:

• To investigate the distinct in vivo functions and subcellular localization of TSP-14A and TSP-14B.
• To elucidate the role of the N-terminal region of TSP-14B in its localization and function.
• To understand the contribution of TspanC8 tetraspanins to C. elegans development.

Main Methods:

• CRISPR-Cas9 gene editing for isoform-specific knock-ins and knock-outs.
• Analysis of gene expression patterns and developmental phenotypes.
• Subcellular localization studies using microscopy.
• Identification of protein motifs responsible for membrane targeting.

Main Results:

• TSP-14A and TSP-14B exhibit overlapping and distinct expression patterns and functions.
• TSP-14A redundantly regulates body size and embryonic/vulva development with TSP-12.
• TSP-14B redundantly regulates postembryonic mesoderm development with TSP-12.
• TSP-14A localizes apically and to endosomes; TSP-14B localizes to the basolateral membrane.
• A di-leucine motif in TSP-14B's N-terminus targets it to the basolateral membrane, which is essential for its function.

Conclusions:

• TSP-14A and TSP-14B possess distinct subcellular localizations and developmental roles.
• Basolateral membrane targeting of TSP-14B, mediated by its N-terminal motif, is critical for its function.
• This study highlights the intricate and diverse functions of TspanC8 tetraspanins in vivo.