Background

Chloride intracellular channel 4 (CLIC4) is a multifunctional metamorphic protein with a growing body of evidence supporting a major role in the brain’s molecular and behavioral response to ethanol. Although key to understanding the functional biology underlying this role, little is known about the cellular and subcellular expression patterns of CLIC4 in brain and how they are affected by ethanol.

Methods

qRT-PCR was used to assess Clic4 mRNA expression in medial prefrontal cortex (mPFC) of C57BL/6J mice in the absence and presence of acute ethanol exposure. Two complementary immunohistochemical techniques were employed to assess the subcellular localization of CLIC4 protein, as well as its pattern of expression across brain cell types in mPFC in the absence and presence of acute ethanol.

Results

Through immunohistochemical and stereological techniques, we show that CLIC4 protein is robustly expressed by oligodendrocytes (most abundant), microglia, and astrocytes, with minimal expression in neurons. Following acute ethanol, we observed a rapid increase in Clic4 mRNA expression in female but not male mice and an overall increase in the number of oligodendrocytes and astrocytes expressing CLIC4 protein.

Conclusions

These findings suggest a function for Clic4 as an early response gene for acute ethanol in brain, which likely underlies its ability to modulate ethanol behavior. Furthermore, our results suggest the role of CLIC4 in the brain’s response to ethanol is likely mediated through oligodendrocytes.