Z-box of insulin gene

Z is a regulatory sequence for the insulin gene.[1] Z is made of 2 different sequences(Za & Zb) in the insulin gene.[2][3]

Z behaves as an enhancer for the transcription of insulin gene in fetal and mature primary islet cells. However, it acts as a repressor for all other cells including immortalized beta cells and beta tumor cells.[2] The deletion of the Z sequence from the insulin gene of primary islet cells results in a decreased insulin production while similar deletions in other cells increase insulin production.[3]

The activity of Z is correlated to the concentration of glucose. The activity of Z is high at higher concentrations of glucose.[2]

References

1. Melloul, D.; Marshak, S.; Cerasi, E. (2002-03-01). "Regulation of insulin gene transcription". Diabetologia. 45 (3): 309–326. doi:10.1007/s00125-001-0728-y. ISSN 1432-0428. PMID 11914736.
2. German, Michael S.; Huang, Juemin; Griffen, Steven C.; Sander, Maike (1998-09-29). "A novel glucose-responsive element in the human insulin gene functions uniquely in primary cultured islets". Proceedings of the National Academy of Sciences. 95 (20): 11572–11577. doi:10.1073/pnas.95.20.11572. ISSN 0027-8424. PMC 21682. PMID 9751707.
3. Olson, L. Karl; Poitout, Vincent; Wicksteed, Barton; Green, Christopher D.; Linning, Katrina D.; Ye, Diana Z.; Pino, Maria F. (2005-05-01). "Elevated Glucose Attenuates Human Insulin Gene Promoter Activity in INS-1 Pancreatic β-Cells via Reduced Nuclear Factor Binding to the A5/Core and Z Element". Molecular Endocrinology. 19 (5): 1343–1360. doi:10.1210/me.2003-0493. ISSN 0888-8809. PMID 15650027.