Taurine biosynthesis by neurons and astrocytes

Area of Science:

• Biochemistry
• Neuroscience
• Cell Biology

Background:

• Taurine is an abundant amino acid with poorly understood physiological roles.
• Taurine deficiency causes severe pathologies, including heart dysfunction and developmental abnormalities.
• The taurine synthesis pathway may be incomplete in astrocytes and neurons, requiring cell cooperation.

Purpose of the Study:

• To investigate the taurine synthesis capability in primary astrocytes, neurons, and various neuroblastoma and glioma cell lines.
• To identify potential limitations in the taurine synthetic pathway within these cell types.

Main Methods:

• Measuring radioactivity incorporation from [(35)S]cysteine into taurine.
• Analyzing taurine synthesis in primary murine astrocytes and neurons.
• Assessing taurine synthesis in human and murine neuroblastoma and human/rat glioma cell lines.
• Investigating the effect of cysteine, cysteamine, and hypertonic conditions on taurine synthesis.

Main Results:

• Significant [(35)S]cysteine incorporation into taurine was observed in rat glioma cells, primary mouse astrocytes, and neurons.
• Elevated intracellular hypotaurine, but not taurine, occurred upon exposure to cysteine or cysteamine.
• Taurine synthesis was enhanced under hypertonic conditions in neurons.

Conclusions:

• Primary astrocytes, neurons, and certain glioma cells possess an intact taurine synthesis pathway.
• Hypotaurine oxidation is a likely limiting step for taurine synthesis.
• Neuronal taurine synthesis is responsive to osmotic stress, consistent with its role as an osmolyte.