CD44 isoform expression mediated by alternative splicing: tissue-specific regulation in mice

Area of Science:

• Molecular Biology
• Cell Biology
• Genetics

Background:

• CD44 is a cell surface glycoprotein with heterogeneous expression due to post-translational modification and alternative splicing.
• Functional studies suggest CD44 acts as an adhesion molecule, with varying ligand-binding capacities in different CD44-expressing cells.
• Structural modifications, including alternatively spliced isoforms, may contribute to CD44's functional heterogeneity.

Purpose of the Study:

• To investigate the expression of CD44 isoforms in mice.
• To determine if alternative splicing of CD44 mRNA contributes to functional heterogeneity.
• To analyze the tissue- and cell-type specific regulation of CD44 alternative splicing.

Main Methods:

• Reverse transcription polymerase chain reaction (RT-PCR) was used to examine CD44 cDNA.
• Southern blotting of PCR products with CD44 probes and oligonucleotides identified multiple CD44 mRNA products.
• Exon-specific primers, cloning, and sequencing were employed to detect and confirm alternatively spliced CD44 mRNA species.

Main Results:

• Multiple CD44 mRNA products larger than the standard form were detected in mouse tumor cell lines and normal tissues.
• Southern blotting revealed unique patterns of alternative CD44 mRNA expression in different mouse tissues, including lymphoid cells.
• At least seven variable exons were involved in alternative splicing, with confirmed sequence identity to genomic CD44 sequences.

Conclusions:

• The mouse expresses multiple variably spliced CD44 isoforms.
• The expression of these CD44 isoforms is regulated in a tissue- and cell-type specific manner.
• Alternative splicing of CD44 mRNA contributes to the diversity of CD44 expression and function.