Hyaluronan synthesis induces microvillus-like cell surface protrusions.

Area of Science:

• Cell Biology
• Biochemistry
• Glycoscience

Background:

• Hyaluronan synthases (HASs) are plasma membrane enzymes responsible for hyaluronan biosynthesis.
• Hyaluronan is a crucial component of the extracellular matrix with diverse biological roles.
• The relationship between HAS activity and cell surface morphology is not well understood.

Purpose of the Study:

• To investigate the role of hyaluronan synthases, specifically HAS3, in cell surface structure.
• To determine if HAS activity can induce plasma membrane protrusions.
• To elucidate the mechanism by which HAS might influence cell morphology.

Main Methods:

• Transfection of cells with green fluorescent protein (GFP)-tagged Has3.
• Microscopy to visualize cell surface structures and analyze microvilli formation.
• Enzymatic assays and pharmacological inhibitors to assess the role of HAS activity.
• Genetic manipulation (CD44 gene disruption) and biochemical treatments (hyaluronidase, oligosaccharides) to probe molecular interactions.

Main Results:

• Cells expressing active GFP-Has3 exhibited numerous microvillus-like protrusions on their dorsal surface.
• Microvilli formation was dependent on HAS enzymatic activity and the presence of functional HAS3.
• These HAS3-induced microvilli were sensitive to hyaluronan synthesis inhibition and degradation, but independent of CD44 receptor interactions.

Conclusions:

• Hyaluronan synthases can actively induce and maintain prominent microvilli on the cell surface.
• The growing hyaluronan chain, tethered during biosynthesis by HAS, acts as a physical scaffold.
• This study introduces a novel concept of the glycocalyx, mediated by HAS, in shaping cell surface architecture.