Neuronal expression of two isoforms of mouse Septin 5

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Septin 5 (Sept5) is a GTPase involved in neuronal exocytosis.
• Alternative splicing produces Sept5_v1 (long) and Sept5_v2 (short) isoforms in rats.
• Sept5_v1 is phosphorylated by Cdk5/p35 at Ser17.

Purpose of the Study:

• To investigate the expression of the Sept5_v1 isoform in mammals.
• To characterize the differential expression and phosphorylation of Sept5 isoforms in the mouse.
• To explore potential isoform-specific functions of Sept5.

Main Methods:

• Polymerase chain reaction (PCR) was used to isolate mouse Sept5_v1 cDNA.
• Northern blotting and Western blotting were employed to analyze mRNA and protein expression.
• Isoform-specific phosphorylation patterns were examined.

Main Results:

• Mouse Sept5_v1 cDNA showed high homology to rat and human sequences.
• Both Sept5 isoforms were expressed in brain and testis mRNA, but only in brain protein.
• Sept5_v1 mRNA was enriched in the cortex and hippocampus, while Sept5_v2 was widespread.
• Protein ratios varied regionally, with distinct developmental expression profiles and N-terminal phosphorylation patterns.

Conclusions:

• Mammalian Sept5 exhibits distinct isoform expression and phosphorylation patterns.
• These differences suggest specialized roles for Sept5_v1 and Sept5_v2.
• Phosphorylation-specific antibodies are valuable tools for studying Sept5 isoform functions.