Transglutaminase inhibitors induce hyperproliferation and parakeratosis in tissue-engineered skin

Br J Dermatol. 2007 Feb;156(2):247-57. doi: 10.1111/j.1365-2133.2006.07641.x.


Background: The transglutaminase (TG) family consists of eight distinct isoforms. TG types 1, 3 and 5 play a major role in normal skin development, with TG2 also being elevated during dermal wounding. TG1, 3 and 5 are responsible for the cross-linking of keratin precursors and formation of the cornified envelope during keratinocyte differentiation. TG2 may play a role in keratinocyte basement membrane cross-linking. Abnormal TG expression has been demonstrated in Darier disease, Netherton syndrome, psoriasis and lamellar ichthyosis. During a recent investigation of skin contraction in tissue-engineered skin, transglutaminase inhibitors were found to produce hyperproliferation and parakeratosis.

Objectives: Accordingly, this study was designed to study the effect of pan-transglutaminase inhibition on morphology of tissue-engineered skin and expression of keratinocyte differentiation and proliferation-associated antigens.

Methods: We used a tissue-engineered model of human skin, based on de-epidermized acellular human dermis, seeded with normal keratinocytes and dermal fibroblasts and cultured at an air-liquid interface. The pan-transglutaminase inhibitors putrescine, NTU283 (1-dimethyl,2-[(oxopropyl)thio]imidazolium) and NTU285 (N-benzyloxycarbonyl-l-glutaminyl-6-dimethylsulfonium-5-oxo-l-norleucine) were added to the culture medium. After 28 days, histology and immunohistochemistry for collagen IV, involucrin and cytokeratins 6, 10 and 16 were performed.

Results: Keratinocyte hyperproliferation and parakeratosis were seen in response to transglutaminase inhibition. Inhibition of transglutaminase also resulted in loss of basement membrane collagen IV. Involucrin and cytokeratins 6 and 16 were confined to the basal layers in control composites but expressed throughout the epidermis in response to transglutaminase inhibition. A distinct band of expression of cytokeratin 10 was seen in the upper stratum granulosum of control composites but only patchy expression was seen after transglutaminase expression.

Conclusions: Pan-transglutaminase inhibition inhibits terminal differentiation of keratinocytes, leading to a hyperproliferative epidermis with parakeratosis and enhanced expression of involucrin and cytokeratins 6 and 16. Expression of the differentiation-associated cytokeratin, cytokeratin 10, is reduced. Basement membrane integrity is also lost as a result of transglutaminase inhibition.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Differentiation*
  • Cell Proliferation*
  • Enzyme Inhibitors / pharmacology*
  • Humans
  • Imidazoles / pharmacology
  • Immunohistochemistry / methods
  • Keratinocytes / cytology*
  • Keratins / metabolism
  • Mucin-1
  • Parakeratosis / chemically induced*
  • Putrescine / pharmacology
  • Skin / enzymology
  • Skin / pathology*
  • Tissue Engineering* / methods
  • Transglutaminases / antagonists & inhibitors*


  • Enzyme Inhibitors
  • Imidazoles
  • Mucin-1
  • 1,3-dimethyl-2-((2-oxopropyl)thio)imidazolium
  • Keratins
  • Transglutaminases
  • Putrescine