Keratini

Keratini are a group of intermediate filaments found in the cytoplasm of epithelial cells. They are composed of keratin proteins, which are rich in alpha-helical domains. Keratini play a crucial role in the structure and function of epithelial tissues, providing mechanical strength and support. They are particularly abundant in skin, hair, nails, and certain internal epithelia such as those lining the gastrointestinal tract and respiratory system.

The primary function of keratini is to maintain the integrity of epithelial tissues. They form a network of filaments that reinforce the cell membrane and the extracellular matrix, helping to withstand physical stress and protect against damage. Keratini also contribute to the barrier function of epithelia, preventing the passage of pathogens and toxins.

Keratini are highly conserved proteins, with different types of keratini expressed in various tissues. For example, type I keratini are found in skin and hair, while type II keratini are present in stratified epithelia like the gastrointestinal tract. The specific composition of keratini can vary depending on the tissue and its specific functions.

In skin, keratini are responsible for the unique properties of the stratum corneum, the outermost layer of the epidermis. This layer is characterized by its high content of dead cells and keratini, which contribute to its waterproof and protective properties. In hair, keratini form the structural framework of the cortex, the main part of the hair shaft.

Keratini are also involved in the process of keratinization, where epithelial cells undergo differentiation and lose their nucleus and other organelles, becoming more resistant to environmental stresses. This process is crucial for the formation of tissues like the stratum corneum and the epidermis of the esophagus.

Research on keratini has implications for understanding skin diseases, hair disorders, and other epithelial-related pathologies. Mutations in keratin genes have been linked to various skin conditions, such as ichthyosis and epidermolysis bullosa. Additionally, keratini are targets for therapeutic interventions aimed at treating skin disorders and promoting wound healing.