CDKN2A point mutations D153spl(c.457G>T) and IVS2+1G>T result in aberrant splice products affecting both p16INK4a and...

Area of Science:

• Genetics
• Molecular Biology
• Oncology

Background:

• The CDKN2A gene on chromosome 9p21 encodes tumor suppressors p16INK4a and p14ARF.
• Germline mutations in CDKN2A are linked to inherited cutaneous malignant melanoma (CMM).
• Approximately 20% of inherited CMM cases are attributed to missense and nonsense mutations affecting CDKN2A protein function.

Purpose of the Study:

• To investigate the functional impact of a specific G>T transversion mutation in exon 2 of the CDKN2A gene.
• To determine the effect of this mutation on both p16INK4a and p14ARF protein expression and function.
• To understand the role of aberrant splicing in CDKN2A-associated melanoma susceptibility.

Main Methods:

• Sanger sequencing to identify the G>T transversion mutation (D153spl, c.457G>T) in the CDKN2A gene.
• Reverse Transcription Polymerase Chain Reaction (RT-PCR) to analyze messenger RNA splicing patterns.
• Analysis of alternative splice products, including exon 2 deletion and exon 2 skipping.

Main Results:

• The identified G>T transversion mutation (D153spl) causes aberrant splicing of the CDKN2A gene.
• This aberrant splicing affects both p16INK4a and p14ARF transcripts, leading to altered protein products.
• Identical aberrant splicing patterns were observed for D153spl and a previously reported IVS2+1G>T mutation.
• Key splice variants include a 74 bp deletion in exon 2 and complete skipping of exon 2.

Conclusions:

• The D153spl mutation in CDKN2A leads to dual inactivation of p16INK4a and p14ARF through aberrant splicing.
• This dual protein inactivation is a potential mechanism contributing to CMM development in families with this mutation.
• Understanding these splicing defects provides insights into the genetic basis of inherited melanoma.