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Alterations in dermal collagen in ultraviolet irradiated hairless mice
E Schwartz1, F A Cruickshank, J S Perlish
1Department of Dermatology, Mount Sinai School of Medicine, New York, New York 10029.
Abstract:
Chronic exposure of the skin to sunlight results in severe dermal connective tissue damage that is characterized by the basophilic degeneration of collagen and the accumulation of an elastotic material. The aim of this study was to identify changes in collagen (the major structural protein of the skin) in ultraviolet irradiated mouse skin using immunochemical and biochemical techniques. Specific antibodies directed against the aminopropeptide of type III procollagen were used in immunofluorescence and immunoblotting studies. Immunofluorescent staining of irradiated and nonirradiated mice skin showed that the aminopropeptide of type III procollagen was distributed throughout the dermis in a pattern similar to that observed for type I collagen. Extracts of irradiated (5 and 10 weeks) and nonirradiated skins were then subjected to immunoblotting techniques. Levels of pN alpha 1, type III procollagen (measured by radioimmunoassay) were reduced in the extracts prepared from skins of mice that were irradiated for 5 and 10 weeks. Immunoelectron microscopy verified the loss of pN alpha 1 type III procollagen in irradiated skin. Collagen fibers of nonirradiated skin demonstrated normal labeling with antibody directed against the aminopropeptide of type III procollagen. In contrast, collagen fibers of 10 week irradiated skin failed to label with this antibody. The pN alpha 1 type III collagen is known to coat type I collagen fibers of normal skin. Therefore, its absence from the surface of type I collagen fibers of irradiated skin may play a role in the development of the elastotic material.
Insights
Chronic UV exposure damages skin collagen. This study found reduced type III procollagen in UV-irradiated mouse skin, suggesting its loss contributes to sun-induced skin aging and elastotic material buildup.
Area of Science:
- Dermatology
- Biochemistry
- Molecular Biology
Background:
- Chronic sun exposure causes skin damage, including collagen degeneration and elastotic material accumulation.
- Collagen is the primary structural protein in skin, crucial for its integrity.
Purpose of the Study:
- To investigate alterations in collagen, specifically type III procollagen, in ultraviolet (UV) irradiated mouse skin.
- To understand the role of type III procollagen changes in the pathogenesis of sun-induced skin damage.
Main Methods:
- Immunofluorescence and immunoblotting techniques were employed using antibodies against the aminopropeptide of type III procollagen.
- Radioimmunoassay was used to quantify type III procollagen levels.
- Immunoelectron microscopy confirmed the localization and presence of type III procollagen.
Main Results:
- Immunofluorescence showed a similar distribution for type III procollagen aminopropeptide as type I collagen in normal skin.
- Levels of pN alpha 1, type III procollagen were significantly reduced in mouse skin irradiated for 5 and 10 weeks.
- Immunoelectron microscopy and antibody labeling confirmed the loss of pN alpha 1 type III procollagen from collagen fibers in irradiated skin.
Conclusions:
- Ultraviolet irradiation leads to a decrease in type III procollagen in mouse skin.
- The absence of pN alpha 1 type III procollagen, which normally coats type I collagen fibers, may contribute to the development of elastotic material in sun-damaged skin.