Alternative non-coding exons support serotonin transporter mRNA expression in the brain and gut

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Polymorphisms in the serotonin transporter (5HTT) gene are linked to affective disorders and anxiety.
• Human 5HTT mRNA exhibits alternative splicing with equal expression in certain cell lines.

Purpose of the Study:

• To investigate alternative splicing of rat 5HTT mRNA.
• To identify distinct 5HTT mRNA splice variants in the rat.
• To determine the tissue-specific expression patterns of these variants.

Main Methods:

• 5' rapid amplification of cDNA ends (5' RACE) to identify splice variants.
• Reverse transcription-polymerase chain reaction (RT-PCR) for expression analysis.
• Exon-specific oligonucleotide hybridization for variant detection.

Main Results:

• Three distinct rat 5HTT mRNA splice variants were identified, differing in their 5' untranslated regions (exons 1A, 1A+1B, and 1C).
• Variant 1A was more abundant in the adult central nervous system (CNS) and adrenal medulla.
• Variants 1A and 1A+1B were equally expressed in the stomach and heart, while variant 1C was primarily found in the gut and heart.

Conclusions:

• Rat 5HTT mRNA undergoes alternative splicing, generating tissue-specific variants.
• The splice variants exhibit differential expression, suggesting complex regulatory mechanisms.
• Variant 1C may be regulated by a distinct promoter compared to variants 1A and 1A+1B.