This study investigates the regulation of the mouse Scgb3a1 gene by the transcription factor NF-Y and its association with CpG methylation in tissue-specific expression. The Scgb3a1 gene encodes a secretoglobin with tumor suppressor function, highly expressed in the lung and trachea of both humans and mice. However, its expression is restricted to specific tissues in mice, such as the lung and mtCC cells derived from SV40-transformed Clara cells, and not in other tissues. The study shows that NF-Y, a ubiquitous transcription factor, binds to "CCAAT" elements in the promoter region of the Scgb3a1 gene and activates its expression. In contrast, the PU-box binding protein has a minimal effect on transcriptional activation. The expression of Scgb3a1 is also associated with CpG methylation in the promoter region. Specifically, two CpG sites closest to the transcription start site are partially or completely unmethylated in tissues where Scgb3a1 is expressed, such as the lung and mtCC cells, but methylated in other tissues. The results suggest that NF-Y is a critical transcription factor for the regulation of Scgb3a1 gene expression, and that tissue-specific expression is influenced by CpG methylation. The study also demonstrates that NF-Y binds to the promoter region of the Scgb3a1 gene in various cell types, including mtCC, NIH3T3, and MLE15 cells, regardless of SCGB3A1 expression. Additionally, the study shows that CpG methylation affects the binding of DNA-binding proteins, which may contribute to the tissue-specific expression of Scgb3a1. The findings highlight the role of NF-Y in the regulation of Scgb3a1 gene expression and the importance of CpG methylation in controlling its tissue-specific expression. The study provides insights into the molecular mechanisms underlying the regulation of this gene and its potential role in tumor suppression.This study investigates the regulation of the mouse Scgb3a1 gene by the transcription factor NF-Y and its association with CpG methylation in tissue-specific expression. The Scgb3a1 gene encodes a secretoglobin with tumor suppressor function, highly expressed in the lung and trachea of both humans and mice. However, its expression is restricted to specific tissues in mice, such as the lung and mtCC cells derived from SV40-transformed Clara cells, and not in other tissues. The study shows that NF-Y, a ubiquitous transcription factor, binds to "CCAAT" elements in the promoter region of the Scgb3a1 gene and activates its expression. In contrast, the PU-box binding protein has a minimal effect on transcriptional activation. The expression of Scgb3a1 is also associated with CpG methylation in the promoter region. Specifically, two CpG sites closest to the transcription start site are partially or completely unmethylated in tissues where Scgb3a1 is expressed, such as the lung and mtCC cells, but methylated in other tissues. The results suggest that NF-Y is a critical transcription factor for the regulation of Scgb3a1 gene expression, and that tissue-specific expression is influenced by CpG methylation. The study also demonstrates that NF-Y binds to the promoter region of the Scgb3a1 gene in various cell types, including mtCC, NIH3T3, and MLE15 cells, regardless of SCGB3A1 expression. Additionally, the study shows that CpG methylation affects the binding of DNA-binding proteins, which may contribute to the tissue-specific expression of Scgb3a1. The findings highlight the role of NF-Y in the regulation of Scgb3a1 gene expression and the importance of CpG methylation in controlling its tissue-specific expression. The study provides insights into the molecular mechanisms underlying the regulation of this gene and its potential role in tumor suppression.