Involucrin Explained

Symbol:Involucrin_N
Involucrin of squamous epithelia N-terminus
Pfam:PF10583
Interpro:IPR019571
Symbol:Involucrin
Involucrin repeat
Pfam:PF00904
Interpro:IPR000354
Scop:1eu0
Symbol:Involucrin2
Involucrin repeat
Pfam:PF06994
Interpro:IPR009733

Involucrin is a protein component of human skin and in humans is encoded by the IVL gene.[1] [2] In binding the protein loricrin, involucrin contributes to the formation of a cell envelope that protects corneocytes in the skin.

Gene

This gene is mapped to 1q21, among calpactin I light chain, trichohyalin, profillaggrin, loricrin, and calcyclin.[2]

Function

Involucrin is a highly reactive, soluble, transglutaminase substrate protein present in keratinocytes of epidermis and other stratified squamous epithelia.[3] [4] It first appears in the cell cytosol, but ultimately becomes cross-linked to membrane proteins by transglutaminase thus helping in the formation of an insoluble envelope beneath the plasma membrane functioning as a glutamyl donor during assembly of the cornified envelope.[5]

Involucrin is synthesised in the stratum spinosum and cross linked in the stratum granulosum by the transglutaminase enzyme that makes it highly stable. Thus it provides structural support to the cell, thereby allowing the cell to resist invasion by micro-organisms.

Apigenin, a plant-derived flavanoid that has significant promise as a skin cancer chemopreventive agent, has been found to regulate normal human keratinocyte differentiation by suppressing involucrin, and this is associated with reduced cell proliferation without apoptosis.[6]

Clinical significance

As one of the precursor proteins of the cornified cell envelope, involucrin is markedly increased in inflammatory skin diseases such as psoriasis[7]

Lamellar ichthyosis involves a decrease in expression of involucrin. This decrease could contribute to the altered desquamation process seen in the disease, since the clinical improvement associated with retinoid treatment is accompanied by increased expression of involucrin.[8]

Structure

Involucrin consists of a conserved N-terminal region of about 75 amino acid residues followed by two extremely variable length segments that contain glutamine-rich tandem repeats. The glutamine residues in the tandem repeats are the substrate for the transglutaminase in the cross-linking reaction. The total size of the protein varies from 285 residues (in dog) to 835 residues (in orangutan).

Further reading

Notes and References

  1. Eckert RL, Green H . Structure and evolution of the human involucrin gene . Cell . 46 . 4 . 583–9 . August 1986 . 2873896 . 10.1016/0092-8674(86)90884-6 . 39293076 .
  2. Web site: Entrez Gene: IVL involucrin.
  3. Green H, Djian P . Consecutive actions of different gene-altering mechanisms in the evolution of involucrin . Molecular Biology and Evolution . 9 . 6 . 977–1017 . November 1992 . 10.1093/oxfordjournals.molbev.a040775 . 1359382 . free .
  4. Djian P, Phillips M, Easley K, Huang E, Simon M, Rice RH, Green H . The involucrin genes of the mouse and the rat: study of their shared repeats . Molecular Biology and Evolution . 10 . 6 . 1136–49 . November 1993 . 10.1093/oxfordjournals.molbev.a040069 . 8277848 . free .
  5. Eckert RL, Yaffe MB, Crish JF, Murthy S, Rorke EA, Welter JF . Involucrin--structure and role in envelope assembly . The Journal of Investigative Dermatology . 100 . 5 . 613–7 . May 1993 . 8098344 . 10.1111/1523-1747.ep12472288 . free .
  6. Balasubramanian S, Zhu L, Eckert RL . Apigenin inhibition of involucrin gene expression is associated with a specific reduction in phosphorylation of protein kinase Cdelta Tyr311 . The Journal of Biological Chemistry . 281 . 47 . 36162–72 . November 2006 . 16982614 . 10.1074/jbc.M605368200 . free .
  7. Takahashi H, Hashimoto Y, Ishida-Yamamoto A, Iizuka H . Roxithromycin suppresses involucrin expression by modulation of activator protein-1 and nuclear factor-kappaB activities of keratinocytes . Journal of Dermatological Science . 39 . 3 . 175–82 . September 2005 . 16140218 . 10.1016/j.jdermsci.2005.03.006 .
  8. Peña-Penabad C, de Unamuno P, García Silva J, Ludeña MD, González Sarmiento R, Pérez-Arellano JL . Altered expression of immunoreactive involucrin in lamellar ichthyosis . European Journal of Dermatology . 9 . 3 . 197–201 . 1999 . 10210784 .

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