Cloning, expression, and chromosome mapping of human galectin-7

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• Galectins are beta-galactoside-binding proteins involved in cell interactions.
• A novel galectin, galectin-7, was identified in human keratinocytes.
• Galectin-7 expression is altered in transformed keratinocytes.

Purpose of the Study:

• To clone and characterize the novel galectin-7.
• To investigate the expression and localization of galectin-7.
• To determine the potential role of galectin-7 in cell growth control.

Main Methods:

• cDNA cloning using a lambda gt11 expression library.
• Two-dimensional gel electrophoresis and lactose binding assays.
• Immunoblotting and immunofluorescence analysis of human tissues and cell lines.

Main Results:

• Galectin-7 was successfully cloned and expressed, comigrating with IEF 17.
• The protein binds lactose and shares conserved amino acids for beta-galactoside interaction.
• Galectin-7 is localized in stratified squamous epithelium, particularly basal keratinocytes, and is down-regulated in SV40 transformed keratinocytes (K14).
• The protein is partially externalized without a typical secretion signal.

Conclusions:

• Galectin-7 is a novel beta-galactoside-binding protein found in stratified squamous epithelium.
• Its down-regulation in transformed keratinocytes suggests a role in cell-cell/cell-matrix interactions and normal growth control.
• The galectin-7 gene is located on chromosome 19.