Betaine Promotes LKB1-AMPK Activation Inhibits UVB-Mediated Senescence of Human Epidermal Keratinocytes Through Autophagy Induction

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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Apigenin and Luteolin Regulate Autophagy by Targeting NRH-Quinone Oxidoreductase 2 in Liver Cells

Antioxidants ◽

10.3390/antiox10050776 ◽

2021 ◽

Vol 10 (5) ◽

pp. 776

Author(s):

Elzbieta Janda ◽

Concetta Martino ◽

Concetta Riillo ◽

Maddalena Parafati ◽

Antonella Lascala ◽

...

Keyword(s):

Potential Role ◽

Autophagic Flux ◽

Ampk Activation ◽

Amp Kinase ◽

Quinone Oxidoreductase ◽

Ampk Phosphorylation ◽

Autophagy Induction ◽

Ampk Activity ◽

Dietary Flavonoids

Dietary flavonoids stimulate autophagy and prevent liver dysfunction, but the upstream signaling pathways triggered by these compounds are not well understood. Certain polyphenols bind directly to NRH-quinone oxidoreductase 2 (NQO2) and inhibit its activity. NQO2 is highly expressed in the liver, where it participates in quinone metabolism, but recent evidence indicates that it may also play a role in the regulation of oxidative stress and autophagy. Here, we addressed a potential role of NQO2 in autophagy induction by flavonoids. The pro-autophagic activity of seven flavonoid aglycons correlated perfectly with their ability to inhibit NQO2 activity, and flavones such as apigenin and luteolin showed the strongest activity in all assays. The silencing of NQO2 strongly reduced flavone-induced autophagic flux, although it increased basal LC3-II levels in HepG2 cells. Both flavones induced AMP kinase (AMPK) activation, while its reduction by AMPK beta (PRKAB1) silencing inhibited flavone-induced autophagy. Interestingly, the depletion of NQO2 levels by siRNA increased the basal AMPK phosphorylation but abrogated its further increase by apigenin. Thus, NQO2 contributes to the negative regulation of AMPK activity and autophagy, while its targeting by flavones releases pro-autophagic signals. These findings imply that NQO2 works as a flavone receptor mediating autophagy and may contribute to other hepatic effects of flavonoids.

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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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