Immunohistochemical localization of lysyl oxidase in normal human skin

Abstract

Lysyl oxidase (EC 1.4.3.13), a copper-dependent enzyme which catalyses the formation of aldehyde cross-links, and acts primarily on collagen and elastin, is known to be increased during wound healing and in fibrotic disorders including liver cirrhosis and atherosclerosis, and to be decreased in some hereditary connective tissue diseases and in malignant cell lines. A recent study showed that lysyl oxidase might possess tumour suppressor activity as an antioncogene for ras. Little is known about the localization of this enzyme in human skin. In this study, we determined immunohistochemically the localization of lysyl oxidase in normal skin of young and elderly subjects obtained from sun-exposed and unexposed regions of the body. All skin samples tested had similar distributions of lysyl oxidase. The enzyme was present both extracellularly and intracellularly. Extracellularly, a few granular aggregates of immunoreactants were observed along collagen and elastic fibres. These granules were more common in the adventitial portion of the dermis than in the reticular portion. Of all sun-exposed and unexposed regions studied, the skin of the face displayed the greatest amount of extracellular immunoreactants. Immunopositive granules were observed intracellularly in fibroblasts, vascular endothelial cells, sweat glands, sebaceous glands, arrector pili muscles and some keratinocytes. These findings provide evidence that, as suggested in recent reports, lysyl oxidase may have a variety of intracellular functions.

Lysyl oxidase activity in human skin is increased by chronic ultraviolet radiation exposure and smoking

“…This finding is consistent with previous studies where increased LOX protein has been detected in photoaged skin. 5 The cytoplasmic location of these enzymes in the epidermis is unusual given their primary role in dermal ECM protein crosslinking; however, this localization is consistent with previous studies of both human and mouse. 6 While the function of these enzymes in the epidermis remains to be fully elucidated, it has been identified that LOX plays a role in maintaining epidermal homeostasis and normal keratinocyte differentiation.…”

Differential Expression of System L Amino Acid Transporters during Wound Healing Process in the Skin of Young and Old Rats

“…Also, other researchers have reported that during the middle and late period of the reformation of matrix, the expression of various proteinases, suppression molecules, metalomatrix proteinases (MMPs) etc., and their inhibitors is elevated or balanced and thus contributes to wound healing. 28,29) Such results reported by previous investigators suggest that proteins playing important roles in each wound healing period are different, 26,27) and such results imply that according to ages also, proteins playing important roles may be different from each other. With our results in this study and previous reports, [26][27][28][29] it is suggested that during the wound healing process after tissue injury, the neutral amino acid transporters LAT1 and LAT2 play the important roles during the early stage of wound healing in young and old rats, respectively.…”

Development of Collagen Fibres and Lysyl Oxidase Expression in the Presumptive Dermis of Chick Limb Bud

“…LOX is expressed in connective tissues where fibrillar collagens and elastin predominate and/or play significant functional roles, such as the skin (Kobayashi et al., 1994), aorta (Wakasaki and Ooshima, 1990) and lung (Hayashi et al., 2004). We have previously reported that both collagen and elastic system fibres emerged and accumulated in a specific temporospatial manner in the presumptive dermis of chick limb buds and that elastin deposition on fibrillin microfibrils coincided with the increase in dermal collagen fibres (Isokawa et al., 2004; Yamazaki et al., 2007).…”