Preface

Chapter 7 **Human Hair as a Testing Substrate in the Era of Precision**

Chapter 8 **Keratinaceous Wastes and Their Valorization through Keratinolytic Microorganisms 129**

Chapter 9 **Keratin Waste: The Biodegradable Polymers 149**

**Section 4 Industrial Treatment of Keratin 127**

Singh Asem

**VI** Contents

Subhash Chandra

**Medicine: Potential Role of 'Omics-Based Approaches 107** Henry Ademola Adeola, Jennifer Cathryn Van Wyk, Afolake Temitope Arowolo and Nonhlanhla Patience Khumalo

Debananda Singh Ningthoujam, Keishing Tamreihao, Saikat Mukherjee, Rakhi Khunjamayum, Laishram Jaya Devi and Roshan

Tarun Kumar Kumawat, Anima Sharma, Vishnu Sharma and

Keratin is the proteinaceous body covering layer produced by mammals, birds, fish, reptiles, and amphibians. Importantly, *keratin* is also the intracellular structural protein that protects living epithelial cells from mechanical damage or stress. The fundamental keratin functions are revealed in congenital human skin diseases caused by mutations in keratin genes, e.g., Epidermolysis bullosa simplex or Epidermolytic hyperkeratosis. Most keratin gene muta‐ tions have a dominant-negative effect disrupting the filamentous structure formation even from the natural allele, and leaving the cell with a deficient cytoskeleton.

In humans, and mammals in general, keratins are encoded by two large families, the Type I and Type II keratin genes. Obligate heterodimers, keratins are differentially expressed in different epithelia. For example, KRT1 and KRT10 are found in the outermost layers of the skin, KRT3 and KRT12 in the cornea, KRT5 and KRT14 in the basal layer of stratified epithelia, KRT8 and KRT18 in the simple, monolayer epithelia, while KRT6, KRT16, and KRT17 are found in certain proliferative pathological conditions, e.g., psoriasis, during wound healing etc.

The expression of keratins is intricately controlled not only by disease situations, but also by hormones, vitamins, immunomodulatory cytokines, and growth factors. Several chapters in this volume describe the regulation of keratin expression.

Hair and wool, horns, claws, hooves, feathers, and scales are made of keratin. Keratin is insolu‐ ble in water and is resistant to proteolysis. However, industrial scale meat production results in vast quantities of keratin byproduct. Processing this byproduct is, on the one hand a major challenge, and on the other hand, a potential for useful recycling and exploitation. Specifically, proteolytic resistance is one major challenge, which necessitates pre-processing of the volumi‐ nous keratin bulk using heat and harsh chemicals. On the other hand, keratin contains impor‐ tant amino acids in large quantities; these are useful as feed or as soil enrichment. Several chapters in this volume describe the aspects of keratin exploitation and commercialization.

### **Miroslav Blumenberg, PhD**

Associate Professor of Dermatology NYU School of Medicine, USA

**Section 1**

**Introduction**

**Section 1**
