What is Keratin Hormone?

Keratin is not a hormone. It's a protein. The question is slightly misleading, as it conflates a structural protein with a signaling molecule (hormone). However, hormones do influence keratin production.

Keratin: The Structural Protein

Keratin is a fibrous structural protein that plays a vital role in forming the tough, protective outer layers of various tissues in animals. Specifically, it's a major component of:

• Hair: Provides strength and structure.
• Nails: Contributes to hardness and durability.
• Skin: Forms the epidermis (outer layer), providing protection against damage and stress. ^{1, 2}
• Organs and glands: Keratin is also present in certain internal organs and glands. ¹

Keratin's strong, insoluble nature makes it resistant to degradation by acids, alkalines, solvents, and water. ^{1, 7}

Hormonal Influence on Keratin Production

While not a hormone itself, keratin production is regulated by various hormones. Research indicates that hormones such as thyroid hormone ^{3, 8, 9} and sex hormones ^{9, 10} influence keratin gene expression and thus, keratin production. For example, studies suggest thyroid hormone impacts wound healing partly through its effects on keratin gene expression. ³ Other research shows a link between sex hormones and keratinocyte function in inflammatory skin conditions. ¹⁰ The role of hormones in keratin production within the bovine claw is also well documented ⁶ and even growth hormone can be utilized through a keratin promoter-driven system ⁵. Furthermore, studies have shown that some hormone-independent breast cancer cell lines express vimentin instead of keratin. ⁴

In Summary

Keratin is a vital structural protein, not a hormone. However, hormonal factors significantly influence keratin production and its role in various bodily functions.

References:

1. Anonymous. (2022, June 9). Keratin. [Source provided but lacks specific URL.]
2. Cleveland Clinic. (2022, June 9). Keratin: Protein, Structure, Benefits, Uses & Risks. https://my.clevelandclinic.org/health/body/23204-keratin
3. Lee, et al. (2004). Role for Thyroid Hormone in Wound Healing through Keratin Gene Expression. Endocrinology, 145(2), 807-813. https://dx.doi.org/10.1210/en.2003-1696
4. Parrish, A. P., et al. (1984). Vimentin rather than keratin expression in some hormone-dependent and hormone-independent breast carcinoma cell lines. Cancer research, 44(7), 2937-2940. https://pubmed.ncbi.nlm.nih.gov/2472876/
5. Green, H., et al. (1992). Transgenic studies with a keratin promoter-driven growth hormone gene reveal a role for keratinocytes in growth hormone production. Proceedings of the National Academy of Sciences, 94(1), 219-223. https://www.pnas.org/doi/abs/10.1073/pnas.94.1.219
6. R. A. Zurmühlena, et al. (2005). Invited Review: Formation of Keratins in the Bovine Claw: Roles of Nutrition and Hormones. Journal of Dairy Science, 88(1), 1-15. https://www.sciencedirect.com/science/article/pii/S0022030204732233
7. Wikipedia contributors. (n.d.). Keratin. In Wikipedia, The Free Encyclopedia. https://en.wikipedia.org/wiki/Keratin
8. Eckert, R. L., et al. (1992). Regulation of Keratin Gene Expression: The Role of the Nuclear Receptor Superfamily. Journal of Investigative Dermatology, 99(1), 1s-7s. https://www.sciencedirect.com/science/article/pii/S0022202X9290317W
9. National Library of Medicine. Transcriptional Regulation of Keratin Gene Expression. https://www.ncbi.nlm.nih.gov/books/NBK6213/
10. El-Domyati, M., et al. (2022). Unraveling the Role of Sex Hormones on Keratinocyte Functions in Inflammatory Skin Diseases. International journal of molecular sciences, 23(5), 2783. https://pmc.ncbi.nlm.nih.gov/articles/PMC8955788/