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Filaggrin expression in epidermolytic ichthyosis (epidermolytic hyperkeratosis)
A Ishida-Yamamoto1, R A Eady, R A Underwood
1St John's Institute of Dermatology, St Thomas' Hospital, London, U.K.
The British Journal of Dermatology
|December 1, 1994
Summary
Filaggrin does not appear to primarily cause keratin clumping in epidermolytic ichthyosis (EH). In some EH cases, filaggrin may interact defectively with keratins, potentially due to altered processing or keratin structure.
Area of Science:
- Dermatology
- Biochemistry
- Cell Biology
Background:
- Epidermolytic ichthyosis (EH) is characterized by abnormal keratinization.
- Filaggrin plays a crucial role in epidermal differentiation and skin barrier function.
- The precise mechanism of keratin filament aggregation in EH remains unclear.
Purpose of the Study:
- To investigate the role of filaggrin in keratin filament aggregation in epidermolytic ichthyosis (EH).
- To determine the temporal relationship between keratin aggregation and filaggrin synthesis during epidermal differentiation in EH.
Main Methods:
- Light and electron microscopic immunohistochemistry on EH skin.
- Biochemical analysis using SDS-PAGE and immunoblotting.
- Immunoelectron microscopy to localize filaggrin and keratin K10.
Main Results:
- Increased filaggrin-immunoreactive cell layers observed in EH, but K10 abnormalities began earlier.
- Keratin filament aggregation precedes profilaggrin synthesis and occurs independently.
- Filaggrin primarily stained keratohyalin granules, while K10 stained keratin filaments; some overlap in partially cornified cells.
- Increased filaggrin/profilaggrin expression without qualitative abnormality detected.
Conclusions:
- Filaggrin is unlikely to be the primary cause of keratin filament clumping in EH.
- Defective interaction between filaggrin and keratins may occur in some EH cases.
- Altered keratin structure or premature processing of profilaggrin could contribute to EH pathogenesis.