Julian Menter, Ph.D.
Research Professor, Department of Medicine
Sun exposure
is unequivocally associated with epidermal (pre)malignancies and with dermal
"photoaging". While significant in vivo damage to dermal collagen
results from UV-induced stimulation of matrix metalloproteins (MMP), direct
interaction of solar UV and dermal collagen is made possible in vivo by the
presence of photolabile fluorescent moieties covalently linked to collagen.
The latter appear primarily as a result of age-related nonenzymatic processes.
Collagen phototransformations could result in a milieu unfavorable for cell
growth and viability by photosensitizing deleterious reactions in situ and/or
producing cytotoxic photoproducts. Altered collagen, could result in MMP and/or
alteration of collagen organization, that may change the environment for fibroblast
growth. Our specific aims are to (1) Characterize the fluorescent collagen
chromophores isolated from dermal type I and type III collagens. (2) Incubate
dermal fibroblasts with unirradiated and, if feasible, irradiated product
fractions isolated in aim #1 above. (3) Test the ability of extracellular
matrix components to modulate the effect of penetrating solar UV wavelengths
on dermal fibroblasts in an in vitro model system. We isolate these fluorophores
from acid and enzymatic extractions of purified Skh-1 mouse as well as from
commercial calf-skin collagen. We will characterize the isolated fluorescent
chromophores by absorption and fluorescence spectroscopy, HPLC, fast atom
bombardment mass-spectroscopy
(FAB-MS), and nuclear magnetic resonance (NMR). We will irradiate the isolated
fluorophores with solar wavelengths followed by analysis as before. Fibroblasts
will be incubated with added reconstituted photoproduct reaction mixture.
We will test fibroblasts for viability, growth, and their dose-response to
UV challenge in the presence and absence of added fluorophore. We will carry
out dose-response in vitro studies to construct survival curves in the presence
and absence of collagen + ground substance proteoglycan and gelatin (denatured
collagen). In other experiments, cells will be incubated with
pre-irradiated collagen prior to UVA. In addition to providing added insight
into photoaging and photocarcinogenesis, experiments will assess the effect
of dermal-penetrating solar UV wavelengths on the architectural and homeostasis
of the resident fibroblasts.
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