How is Keratin Produced?
Keratin, a fibrous structural protein, is produced within specialized cells called keratinocytes. These cells undergo a process of transformation called keratinization, ultimately resulting in the formation of tough, protective keratin.
The process begins with keratinocytes, which are derived from the ectoderm (the outermost layer of embryonic tissue). [10] These cells synthesize and assemble keratin proteins into intermediate filaments. As keratinocytes mature and migrate upward through the epidermis (the outer layer of skin), they gradually fill with keratin. This process involves a series of structural and biochemical changes, including the formation of cross-links between keratin filaments, which strengthens and toughens the cells. The keratinocytes eventually die, leaving behind a layer of compacted, keratin-filled cells known as the stratum corneum—the outermost, protective layer of skin. [10] This is essentially a pile of dead cells containing keratin.
Keratin production is regulated at the molecular level by the expression of keratin genes, which dictate the type and amount of keratin produced. This expression is cell-type dependent, meaning the level of mRNA controlling keratin synthesis varies in different keratinocyte populations. [Reddit] Different types of keratin exist, leading to diverse keratin-rich structures such as hair, nails, and horns, all depending on the specific keratin genes expressed. [Study.com]
Types of Keratin
It is important to note that there are different types of keratins. Alpha-keratin (α-keratin) is the main type found in vertebrates, forming the basis of hair, nails, and skin. [Wikipedia] There are also primary keratins, which are routinely synthesized by epithelial cells, and secondary keratins, produced under specific conditions by these cells. [PMC5917548]
Keratin's Composition
Keratin is a polypeptide protein composed of various amino acids linked together by disulfide bonds. [ScienceDirect] The arrangement of these amino acids and the extent of disulfide bonding influence the properties of the resulting keratin, impacting the final structure's flexibility and strength. Dietary protein intake plays a role, as amino acids are the building blocks for all proteins, including keratin. [Quora] However, while diet can influence overall health and potentially support keratin production indirectly, it's primarily the inherent cellular processes that directly determine the amount and type of keratin generated by the body. [MedicalNewsToday]
Summary
In summary, keratin is not a secretion but a product of keratinocyte differentiation and the keratinization process. The amount and type of keratin produced are genetically regulated and vary among different cell types and structures within the body.
