Maspin/SerpinB5 is a cytoskeleton-binding protein that regulates epithelial cell shape

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Maspin (SerpinB5) is an abundant protein primarily expressed by epithelia.
• Initially identified as a tumor suppressor, Maspin regulates cell adhesion, migration, and invasion.
• The intracellular mechanisms by which Maspin orchestrates these cellular processes remain largely unclear.

Purpose of the Study:

• To elucidate the intracellular functions of Maspin in regulating cytoskeletal dynamics and cell morphology.
• To identify direct protein interaction partners of Maspin within the cell.

Main Methods:

• Affinity purification-Mass spectrometry (AP/MS) to identify Maspin-interacting proteins.
• CRISPR/Cas9-mediated GFP tagging of endogenous Maspin for localization studies.
• RNA interference (RNAi) and CRISPR/Cas9 for Maspin depletion experiments.
• In vitro microtubule polymerization assays.

Main Results:

• Maspin directly interacts with both microtubules and microfilaments.
• Endogenous Maspin localizes to the cortical cytoskeleton and mitotic spindle.
• Maspin depletion alters cell-cell contacts, induces cytoskeletal rearrangements, and affects cell shape during mitosis.
• Maspin suppresses microtubule growth both in vitro and within cells.

Conclusions:

• Maspin plays a dynamic role at the cell cortex and mitotic spindle, interacting with cytoskeletal elements.
• Maspin modulates cell adhesion, cell shape, and cytoskeletal organization.
• These findings reveal novel intracellular functions of Maspin in epithelial cell biology.