Researchers have identified Fibulin-5 as a target of the enzyme Granzyme B, offering a new explanation for how UV exposure breaks down skin's elastic structure.
A single protein may help explain why sun-damaged skin loses its elasticity in ways that elastic fiber degradation alone cannot account for.
Researchers publishing in the Journal of Investigative Dermatology identified Fibulin-5 as a substrate of Granzyme B, an enzyme increasingly linked to tissue damage in photoaged skin. The finding adds a previously missing piece to a long-standing question in dermatology.
Photoaged skin, the study noted, does not simply lose elastic fibers. It replaces them with disorganised structures in the extracellular matrix that lack functional elasticity — a distinction the researchers described as significant. Prior work, including studies by Makino et al. (2021) and Charoenchon et al. (2018), had documented the accumulation of elastotic material and the loss of fibrillins and fibulins in the papillary dermis. Elastase has long been considered the primary driver of that degradation, according to Chung et al. (2002).
What the new research suggests is that Granzyme B acts on Fibulin-5 specifically under UVB exposure, disrupting the scaffolding that keeps elastic fibers organised. The mechanisms behind photoaged skin's structural disorganisation, the authors noted, have remained poorly understood until now.
For people with albinism — who have reduced or absent melanin and therefore absorb UVB radiation with little natural protection — research into the precise pathways of UV-induced skin damage carries particular weight. Understanding how structural proteins break down under sun exposure is a step toward more targeted protective and clinical strategies.
The paper was published in the Journal of Investigative Dermatology.
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