Laminin isoform profiles in salivary glands in Sjögren's syndrome

Adv Clin Chem. 2011:55:35-59. doi: 10.1016/b978-0-12-387042-1.00003-4.

Abstract

Five different laminin (LM) alpha, four LM-beta, and three LM-gamma chains form the 15-16 currently known approximately 400-900 kDa heterodimeric LM-monomers, which self-assemble in the lamina lucida of the basement membrane (BM) to a network, connected with nidogens and perlecans with the underlying type IV collagen network. In labial salivary glands (LSG), the structurally organizing/polarizing BM separates the tubuloacinar epithelium from the connective tissue stroma but plays regulatory roles as well. Tissue distribution of LM-alpha, -beta, and -gamma chains is described, and application of the known combinatorial rules allows some conclusions also on the corresponding distribution of the LM-trimers. Currently, known integrin (Int) and non integrin (e.g., dystroglycans and Lutheran blood group antigens) LM-receptors are described. LMs are regulated at transcriptional, translational, and posttranslational levels, together with the regulation of alternative splicing, binding partners (assembly), secretion, and degradation. In LSGs, LM-alpha1, -alpha2, and -alpha4 are only found in the acinar (not ductal) BM, LM-alpha4 also in the periductal/ interstitial stroma. Pattern recognition disclosed irregular expression in the acinar BM, suggesting some dynamic and/or regulatory role. It seems that in a female-dominant autoimmune exocrinopathy, Sjögren's syndrome (SS), LM-alpha1 and -alpha2 are decreased, together with their Int alpha1beta1 and alpha2beta1 receptors. Because LM-111/211-to-Int-alpha1beta1/alpha2beta1 interactions play a crucial role in the transdifferentiation of the intercalated duct progenitors to secretory acinar cells, acinar remodeling is impaired in SS. Disturbed hemidesmosomal Int alpha6beta4/LM-332 interactions in SS may lead to acinar cell anoikis. Interestingly, dehydroepiandrosterone (DHEA) prohormone and its intracrine androgenic dihydrotestosterone (DHT) end product upregulate at least Int alpha1beta1/alpha2beta1, whereas LM-alpha1 is upregulated by outside-in LM-111/211-to-Int-alpha1beta1/alpha2beta1 signaling. It seems that LM alterations precede the lymphocyte infiltration, suggesting that acinar BM-Int pathology, perhaps related to endo- and intracrine sex steroid metabolism, represents an early pathogenic phases in SS.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Acinar Cells / metabolism
  • Acinar Cells / pathology
  • Basement Membrane / metabolism
  • Basement Membrane / pathology
  • Blotting, Western
  • Cell Transdifferentiation
  • Collagen Type IV / genetics
  • Collagen Type IV / metabolism
  • Fluorescent Antibody Technique
  • Gene Expression Profiling
  • Gene Expression*
  • Humans
  • Integrin alpha1beta1 / metabolism
  • Laminin* / chemistry
  • Laminin* / classification
  • Laminin* / genetics
  • Laminin* / metabolism
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism
  • Organ Specificity
  • Protein Isoforms* / chemistry
  • Protein Isoforms* / classification
  • Protein Isoforms* / genetics
  • Protein Isoforms* / metabolism
  • Receptors, Laminin / genetics
  • Receptors, Laminin / metabolism
  • Salivary Glands / metabolism*
  • Salivary Glands / pathology
  • Sjogren's Syndrome / metabolism*
  • Sjogren's Syndrome / pathology
  • Sjogren's Syndrome / physiopathology

Substances

  • Collagen Type IV
  • Integrin alpha1beta1
  • Laminin
  • Membrane Glycoproteins
  • Protein Isoforms
  • Receptors, Laminin
  • nidogen