Adenomatous polyposis coli localization is both cell type and cell context dependent.

Area of Science:

• Cell Biology
• Molecular Biology
• Cancer Research

Background:

• The adenomatous polyposis coli (APC) protein, a tumor suppressor, is frequently mutated in colorectal cancers.
• APC plays roles in WNT signaling, cell migration, and mitosis.
• APC's presence at the cell cortex in mammalian cells is debated, with some studies showing lateral membrane localization.

Purpose of the Study:

• To investigate the subcellular localization of APC in different cell types and contexts.
• To determine if APC exhibits cortical localization in mammalian cells.
• To understand the factors influencing APC's subcellular distribution.

Main Methods:

• Immunostaining of rat epithelial (NRK-52E) and fibroblast (NRK-49F) cell lines.
• Analysis of APC localization in subconfluent and confluent cell cultures.
• Calcium switch experiments to assess APC recruitment during cell junction formation.
• Wounding assays to observe APC localization changes in response to tissue damage.

Main Results:

• Microtubule-associated APC populations were observed in both subconfluent NRK-52E and NRK-49F cells.
• Confluent NRK-52E monolayers, but not NRK-49F, displayed a distinct cortical APC distribution.
• Cortical APC localized near cell junction proteins independently of microtubules.
• APC recruitment to the cortex occurred upon complete junction assembly.
• Wounding assays revealed differential APC localization in confluent NRK-49F and NRK-52E cells.

Conclusions:

• Cortical APC localization is a characteristic feature of confluent epithelioid cells.
• APC's subcellular distribution is dependent on both cell type and cellular context.
• These findings contribute to understanding APC's role beyond WNT signaling, particularly in cell adhesion and tissue integrity.