Functional link between tyrosine phosphorylation and human serotonin transporter gene expression

Area of Science:

• Pharmacology
• Molecular Biology
• Cell Biology

Background:

• The serotonin transporter (SERT) plays a crucial role in regulating serotonergic neurotransmission.
• Understanding the regulation of SERT gene expression is vital for neurological and psychiatric research.

Purpose of the Study:

• To investigate the effect of herbimycin A, a tyrosine kinase inhibitor, on human serotonin transporter expression and activity.
• To elucidate the role of tyrosine phosphorylation in regulating SERT gene expression.

Main Methods:

• Treatment of JAR human placental choriocarcinoma cells with herbimycin A.
• Analysis of serotonin transporter activity, density, and mRNA levels.
• Inhibition studies using actinomycin D, cycloheximide, and genistein.
• Assessment of tyrosine phosphorylation of cellular proteins.

Main Results:

• Herbimycin A increased serotonin transporter activity, density, and mRNA levels in a time-dependent manner (> 4 h).
• The effects of herbimycin A were blocked by actinomycin D and cycloheximide, indicating a requirement for new protein synthesis and mRNA stability.
• Genistein abolished the increase in transporter activity but not mRNA levels, suggesting distinct pathways for activity and expression regulation.
• Herbimycin A treatment led to increased tyrosine phosphorylation of specific proteins.

Conclusions:

• Tyrosine phosphorylation is essential for the herbimycin A-induced increase in serotonin transporter activity.
• Tyrosine phosphorylation is a critical component in the signaling pathways regulating human serotonin transporter gene expression.