Lipocortin I is a component of the cell envelope of human epidermal keratinocytes

The cell envelope (CE) is a specialized structure that is important for barrier function in terminally differentiated stratified squamous epithelia. The CE is formed inside the plasma membrane and becomes insoluble as a result of cross-linking of constituent proteins by isopeptide bonds formed by transglutaminases. To investigate the earliest stages of assembly of the CE, we have studied human epidermal keratinocytes induced to terminally differentiate in submerged liquid culture as a model system for epithelia in general. CEs were harvested from 2-, 3-, 5-, or 7-d cultured cells and examined by 1) immunogold electron microscopy using antibodies to known CE or other junctional proteins and 2) amino acid sequencing of cross-linked peptides derived by proteolysis of CEs. Our data document that CE assembly is initiated along the plasma membrane between desmosomes by head-to-tail and head-to-head cross-linking of involucrin to itself and to envoplakin and perhaps periplakin. Essentially only one lysine and two glutamine residues of involucrin and two glutamines of envoplakin were used initially. In CEs of 3-d cultured cells, involucrin, envoplakin, and small proline-rich proteins were physically located at desmosomes and had become cross-linked to desmoplakin, and in 5-d CEs, these three proteins had formed a continuous layer extending uniformly along the cell periphery. By this time >15 residues of involucrin were used for cross-linking. The CEs of 7-d cells contain significant amounts of the protein loricrin, typically expressed at a later stage of CE assembly. Together, these data stress the importance of juxtaposition of membranes, transglutaminases, and involucrin and envoplakin in the initiation of CE assembly of stratified squamous epithelia.

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Alterations of ultrastructure and elemental composition in cultured human epidermal keratinocytes after treatment with nitrofurazone and silver sulfadiazine

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100127803 ◽

1987 ◽

Vol 45 ◽

pp. 676-677

Author(s):

A. R. Crooker ◽

M. C. Myers ◽

T. L. Beard ◽

E. S. Graham

Keyword(s):

Electron Microscopy ◽

Elemental Composition ◽

Pyrolytic Carbon ◽

Human Keratinocytes ◽

Silver Sulfadiazine ◽

Epidermal Keratinocytes ◽

Human Epidermal Keratinocytes ◽

Culture Systems ◽

Cytotoxicity Endpoints

Cell culture systems have become increasingly popular as a means of screening toxic agents and studying toxic mechanisms of drugs and other chemicals at the cellular and subcellular levels. These in vitro tests can be conducted rapidly in a broad range of relevant mammalian culture systems; a variety of biological and biochemical cytotoxicity endpoints can be examined. The following study utilized human keratinocytes to evaluate the relative cytotoxicities of nitrofurazone (NF) and silver sulfadiazine (SS), the active ingredients of FURACIN(R) Topical Cream and SILVADENE(R) Cream, respectively. These compounds are anti-infectives used in the treatment of burn patients. Cell ultrastructure and elemental composition were utilized as cytotoxicity endpoints.Normal Human Epidermal Keratinocytes (HK) were prepared from the EpiPackTM culture system (Clonetics Corporation, Boulder, CO). For scanning electron microscopy (SEM) and transmission electron microscopy (TEM), cells were seeded on sterile 35 mm Falcon plastic dishes; for elemental microanalysis, cells were plated on polished pyrolytic carbon discs (E. Fullam, Latham, NY) placed in the culture dishes.

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Regulation of transglutaminase type II by transforming growth factor-beta 1 in normal and transformed human epidermal keratinocytes.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)38562-x ◽

1990 ◽

Vol 265 (19) ◽

pp. 11098-11104 ◽

Cited By ~ 1

Author(s):

M D George ◽

T M Vollberg ◽

E E Floyd ◽

J P Stein ◽

A M Jetten

Keyword(s):

Growth Factor ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Epidermal Keratinocytes ◽

Type Ii ◽

Human Epidermal Keratinocytes ◽

Growth Factor Beta

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Antioxidant and Pro-Oxidant Capacities as Mechanisms of Photoprotection of Olive Polyphenols on UVA-Damaged Human Keratinocytes

Molecules ◽

10.3390/molecules26082153 ◽

2021 ◽

Vol 26 (8) ◽

pp. 2153

Author(s):

Raffaella Marina Lecci ◽

Isabella D’Antuono ◽

Angela Cardinali ◽

Antonella Garbetta ◽

Vito Linsalata ◽

...

Keyword(s):

Antioxidant Activities ◽

Biological Activities ◽

Human Keratinocytes ◽

Ldl Oxidation ◽

Trolox Equivalent Antioxidant Capacity ◽

Epidermal Keratinocytes ◽

Olive Cultivar ◽

Human Epidermal Keratinocytes ◽

Apoptotic Effect

A wide variety of polyphenols are reported to have considerable antioxidant and skin photoprotective effects, although the mechanisms of action are not fully known. Environmentally friendly and inexpensive sources of natural bioactive compounds, such as olive mill wastewater (OMWW), the by-product of olive-oil processing, can be considered an economic source of bioactive polyphenols, with a range of biological activities, useful as chemotherapeutic or cosmeceutical agents. Green strategies, such as the process based on membrane technologies, allow to recover active polyphenols from this complex matrix. This study aims to evaluate the antioxidant, pro-oxidant, and photoprotective effects, including the underlying action mechanism(s), of the ultra-filtered (UF) OMWW fractions, in order to substantiate their use as natural cosmeceutical ingredient. Six chemically characterized UF-OMWW fractions, from Italian and Greek olive cultivar processing, were investigated for their antioxidant activities, measured by Trolox Equivalent Antioxidant Capacity (TEAC), LDL oxidation inhibition, and ROS-quenching ability in UVA-irradiated HEKa (Human Epidermal Keratinocytes adult) cultures. The photoprotective properties of UF-OMWW were assayed as a pro-oxidant-mediated pro-apoptotic effect on the UVA-damaged HEKa cells, which can be potentially involved in the carcinogenesis process. All the UF-OMWW fractions exerted an effective antioxidant activity in vitro and in cells when administered together with UV-radiation on HEKa. A pro-oxidative and pro-apoptotic effect on the UVA-damaged HEKa cells were observed, suggesting some protective actions of polyphenol fraction on keratinocyte cell cultures.

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