Distribution of ASIC4 transcripts in the adult wild-type mouse brain

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Acid-sensing ion channels (ASICs) are proton-gated cation channels crucial for neuronal function.
• Acid-sensing ion channel 4 (ASIC4) is the least understood member of the ASIC family, with its detailed brain distribution previously unclear.
• ASIC4 is known to be expressed in the spinal cord and several brain regions, but a comprehensive map is lacking.

Purpose of the Study:

• To elucidate the detailed distribution of Acid-sensing ion channel 4 (ASIC4) transcripts in the mammalian brain.
• To map ASIC4 expression patterns using both in situ hybridization and reporter mouse models.
• To identify specific neuronal populations expressing ASIC4, particularly in the basal forebrain.

Main Methods:

• Radioactive in situ hybridization histochemistry using an ASIC4-specific cRNA probe on wild-type mouse brains.
• X-gal staining on Asic4-lacZ reporter mice (Asic4tm1a(KOMP)Mbp) to visualize ASIC4 expression.
• Combined X-gal staining and immunohistochemistry to identify ASIC4 activity in specific cell types, such as choline acetyltransferase (ChAT)-positive neurons.

Main Results:

• ASIC4 mRNAs were found to be widely expressed throughout the wild-type mouse brain.
• Preferential concentration of ASIC4 transcripts was observed in regions including the olfactory bulb, piriform cortex, caudate putamen, and amygdaloid complex.
• Intense ASIC4 transcriptional activity was detected in basal forebrain cholinergic neurons, co-localizing with choline acetyltransferase (ChAT).

Conclusions:

• This study provides a detailed map of ASIC4 mRNA distribution in the mouse brain.
• The findings highlight specific brain regions and neuronal populations with significant ASIC4 expression.
• The identified expression patterns suggest potential roles for ASIC4 in diverse brain functions, including cholinergic neurotransmission.