Keratinocyte

keratinocytesskin cellsdead skin cellscellscells in the outer layer of the skinkeratinocyte proliferationkeratinocytes (keratin cells)skin cellsunburn cell
Keratinocytes constitute 90% of the cells of the epidermis, the outermost layer of the skin.wikipedia
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Hemidesmosome

hemidesmosomeshemidesmosomaladhesion complexes
Epidermal stem cells reside in the lower part of the epidermis (stratum basale) and are attached to the basement membrane through hemidesmosomes.
Hemidesmosomes are very small stud-like structures found in keratinocytes of the epidermis of skin that attach to the extracellular matrix.

Corneocyte

corneocytescornified cell envelope
During this differentiation process, keratinocytes permanently withdraw from the cell cycle, initiate expression of epidermal differentiation markers, and move suprabasally as they become part of the stratum spinosum, stratum granulosum, and eventually corneocytes in the stratum corneum.
Corneocytes are terminally differentiated keratinocytes and compose most if not all of the stratum corneum, the outermost part of the epidermis.

Desquamation

skin peelingdesquamateddesquamating
Corneocytes will eventually be shed off through desquamation as new ones come in.
Normal, nonpathologic desquamation of the skin occurs when keratinocytes, after moving typically over about 14 days, are individually shed unnoticeably.

Stratum granulosum

granular layerGranular layer of skingranulosum
During this differentiation process, keratinocytes permanently withdraw from the cell cycle, initiate expression of epidermal differentiation markers, and move suprabasally as they become part of the stratum spinosum, stratum granulosum, and eventually corneocytes in the stratum corneum.
Keratinocytes migrating from the underlying stratum spinosum become known as granular cells in this layer.

Stratum basale

basal layerbasal cellsStratum germinativum
Basal cells in the basal layer (stratum basale) of the skin, are sometimes referred to as basal keratinocytes.
Some basal cells can act like stem cells with the ability to divide and produce new cells, and these are sometimes called basal keratinocyte stem cells.

Stratum corneum

horny layercornified layerepidermal permeability barrier
During this differentiation process, keratinocytes permanently withdraw from the cell cycle, initiate expression of epidermal differentiation markers, and move suprabasally as they become part of the stratum spinosum, stratum granulosum, and eventually corneocytes in the stratum corneum.
Desquamation, the process of cell shedding from the surface of the stratum corneum, balances proliferating keratinocytes that form in the stratum basale.

Keratin 5

KRT5K55
At each stage of differentiation, keratinocytes express specific keratins, such as keratin 1, keratin 5, keratin 10, and keratin 14, but also other markers such as involucrin, loricrin, transglutaminase, filaggrin, and caspase 14.
Keratin 5 (and K14) are expressed primarily in basal keratinocytes in the epidermis, specifically in the stratified epithelium lining the skin and digestive tract.

Involucrin

IVL
At each stage of differentiation, keratinocytes express specific keratins, such as keratin 1, keratin 5, keratin 10, and keratin 14, but also other markers such as involucrin, loricrin, transglutaminase, filaggrin, and caspase 14.
Involucrin is a highly reactive, soluble, transglutaminase substrate protein present in keratinocytes of epidermis and other stratified squamous epithelia.

Melanocyte

melanocytesmelanogenesismelanocytic
Within the epidermis keratinocytes are associated with other cell types such as melanocytes and Langerhans cells.
Once synthesized, melanin is contained in special organelles called melanosomes which can be transported to nearby keratinocytes to induce pigmentation.

Stratum spinosum

prickle cell layerspinosumspinous layer
During this differentiation process, keratinocytes permanently withdraw from the cell cycle, initiate expression of epidermal differentiation markers, and move suprabasally as they become part of the stratum spinosum, stratum granulosum, and eventually corneocytes in the stratum corneum.
This layer is composed of polyhedral keratinocytes.

Skin

cutaneousskin cellanimal skin
Keratinocytes constitute 90% of the cells of the epidermis, the outermost layer of the skin.
It forms a protective barrier over the body's surface, responsible for keeping water in the body and preventing pathogens from entering, and is a stratified squamous epithelium, composed of proliferating basal and differentiated suprabasal keratinocytes.

Keratin

keratinizationkeratinouskeratinized
At each stage of differentiation, keratinocytes express specific keratins, such as keratin 1, keratin 5, keratin 10, and keratin 14, but also other markers such as involucrin, loricrin, transglutaminase, filaggrin, and caspase 14. A number of structural proteins (filaggrin, keratin), enzymes (proteases), lipids, and antimicrobial peptides (defensins) contribute to maintain the important barrier function of the skin.
Keratin filaments are abundant in keratinocytes in the cornified layer of the epidermis; these are proteins which have undergone keratinization.

Rotating locomotion in living systems

cartwheelingrollingrolling and wheeled creatures
Keratinocytes migrate with a rolling motion during the process of wound healing.
Keratinocytes, a type of skin cell, migrate with a rolling motion during the process of wound healing.

TGF alpha

transforming growth factor alphaTGF-αTGFA
TGF-α can be produced in macrophages, brain cells, and keratinocytes.

Epidermis

epidermalepidermal cellsepidermal layer
Keratinocytes constitute 90% of the cells of the epidermis, the outermost layer of the skin.
The epidermis primarily consists of keratinocytes (proliferating basal and differentiated suprabasal), which comprise 90% of its cells, but also contains melanocytes, Langerhans cells, Merkel cells, and inflammatory cells.

Actinic keratosis

actinic keratosessolar keratosissenile keratosis
They may also be found in graft-versus-host disease, adverse drug reactions, inflammatory keratosis (such as lichenoid actinic keratosis and lichen planus-like keratosis), erythema multiforme, bullous pemphigoid, eczema, lichen planopilaris, febrile neutrophilic dermatosis, toxic epidermal necrolysis, herpes simplex and varicella zoster lesions, dermatitis herpetiformis, porphyria cutanea tarda, sarcoidosis, subcorneal pustular dermatosis, transient acantholytic dermatosis and epidermolytic hyperkeratosis.
The term actinic keratosis can be literally understood as a disorder (-osis) of epidermal keratinocytes that is induced by ultraviolet (UV) light exposure (actin-).

Melanosome

melanosomes
Keratinocytes contribute to protecting the body from ultraviolet radiation (UVR) by taking up melanosomes, vesicles containing the endogenous photoprotectant melanin, from epidermal melanocytes.
The pseudopodial process (aka the tanning process) happens slowly in dermal melanocytes in response to ultraviolet light and to production of new melanosomes and increased donation of melanosomes to adjacent keratinocytes, which are typical skin surface cells.

Immune system

immuneimmune responseimmune function
Keratinocytes also modulate the immune system: apart from the above-mentioned antimicrobial peptides and chemokines they are also potent producers of anti-inflammatory mediators such as IL-10 and TGF-β.
Other immune system cells that are known to express CYP27B1 and thus activate vitamin D calcidiol, are dendritic cells, keratinocytes and macrophages.

Skin condition

Skin lesionskin diseasepustule
Civette bodies are characteristically found in skin lesions of various dermatoses, particularly lichen planus and discoid lupus erythematosus.
The epidermis contains four cell types: keratinocytes, melanocytes, Langerhans cells, and Merkel cells.

Wound healing

wound repairscabvulnerary
Keratinocytes migrate with a rolling motion during the process of wound healing.
Basal keratinocytes from the wound edges and dermal appendages such as hair follicles, sweat glands and sebacious (oil) glands are the main cells responsible for the epithelialization phase of wound healing.

Melanin

eumelaninpheomelaninphaeomelanin
Keratinocytes contribute to protecting the body from ultraviolet radiation (UVR) by taking up melanosomes, vesicles containing the endogenous photoprotectant melanin, from epidermal melanocytes.
These are then transferred into the keratinocyte cells of the human epidermis.

Keratosis

keratotickeratosesfrictional keratosis
They may also be found in graft-versus-host disease, adverse drug reactions, inflammatory keratosis (such as lichenoid actinic keratosis and lichen planus-like keratosis), erythema multiforme, bullous pemphigoid, eczema, lichen planopilaris, febrile neutrophilic dermatosis, toxic epidermal necrolysis, herpes simplex and varicella zoster lesions, dermatitis herpetiformis, porphyria cutanea tarda, sarcoidosis, subcorneal pustular dermatosis, transient acantholytic dermatosis and epidermolytic hyperkeratosis.

HaCaT

HaCaT is a spontaneously transformed aneuploid immortal keratinocyte cell line from adult human skin, widely used in scientific research.

Toxic epidermal necrolysis

Lyell's syndromeLyell syndromeepidermal necrolysis, toxic
They may also be found in graft-versus-host disease, adverse drug reactions, inflammatory keratosis (such as lichenoid actinic keratosis and lichen planus-like keratosis), erythema multiforme, bullous pemphigoid, eczema, lichen planopilaris, febrile neutrophilic dermatosis, toxic epidermal necrolysis, herpes simplex and varicella zoster lesions, dermatitis herpetiformis, porphyria cutanea tarda, sarcoidosis, subcorneal pustular dermatosis, transient acantholytic dermatosis and epidermolytic hyperkeratosis.
Keratinocytes are the cells found lower in the epidermis and specialize in holding the surrounding skin cells together.