Laminin N-terminus α31 protein distribution in adult human tissues

Abstract

Laminin N-terminus α31 (LaNt α31) is a netrin-like protein derived from alternative splicing of the laminin α3 gene. Although LaNt α31 has been demonstrated to influence corneal and skin epithelial cell function, its expression has not been investigated beyond these tissues. In this study, we used immunohistochemistry to characterise the distribution of this protein in a wide-array of human tissue sections in comparison to laminin α3. The data revealed widespread LaNt α31 expression. In epithelial tissue, LaNt α31 was present in the basal layer of the epidermis, throughout the epithelium of the digestive tract, and in much of the epithelium of the reproductive system. LaNt α31 was also found throughout the vasculature of most tissues, with enrichment in reticular-like fibres in the extracellular matrix surrounding large vessels. A similar matrix pattern was observed around the terminal ducts in the breast and around the alveolar epithelium in the lung, where basement membrane staining was also evident. Specific enrichment of LaNt α31 was identified in sub-populations of cells of the kidney, liver, pancreas, and spleen, with variations in intensity between different cell types in the collecting ducts and glomeruli of the kidney. Intriguingly, LaNt α31 immunoreactivity was also evident in neurons of the central nervous system, in the cerebellum, cerebral cortex, and spinal cord. Together these findings suggest that LaNt α31 may be functionally relevant in a wider range of tissue contexts than previously anticipated, and the data provides a valuable basis for investigation into this interesting protein.

Laminin N-terminus α31 is upregulated in invasive ductal breast cancer and changes the mode of tumour invasion

“…The LMα3 antibodies used recognise both the LMα3a and LMα3b forms. LaNt α31 and LMα3 displayed very similar distribution in the normal tissue ( Fig 1A ), primarily restricted to TDLU as previously reported [ 28 ], with the most intense immunoreactivity being present in the extracellular matrix surrounding the TDLU. However, much stronger and more widespread cellular LaNt α31 expression was detected in three of the four invasive ductal carcinoma and three of the four triple negative specimens.…”

“…Mouse monoclonal antibodies raised against human LaNt α31 were described previously and were used at 0.225 μg mL -1 for IHC [ 12 , 28 ]. Mouse monoclonal antibodies against human LMα3 (clone CL3112) and mouse IgG (both Sigma-Aldrich, St. Louis, Missouri, USA) were used at 0.5 μg mL -1 .…”

Laminin N‐terminus α31 expression during development is lethal and causes widespread tissue‐specific defects in a transgenic mouse model

“…We focused our attention on kidney, skin and lung as examples of tissues where the BMs with distinct differences in LM composition and where LaNt α31 could elicit context‐specific effects. Each of these three tissues also express LaNt α31 in adult human tissue, and are, therefore, tissues where dysregulation of expression regulation could be physiologically relevant 37 . Specifically, the predominant LMs in the kidney contain three LN domains, and mutations affecting LM polymerization lead to Pierson syndrome, 19,57–60 whereas the major LM in the skin contains one LN domain, LM332, and loss of function leads to skin fragility, reviewed in, 61 and granulation tissue disorders 62,63 .…”

“…LaNt α31 is expressed in the basal layer of epithelia in the skin, 24 cornea 36 and digestive tract, the ECM around terminal duct lobular units of the breast and alveolar air sacs in the lung, and is widely expressed by endothelial cells. 37 Increased expression is associated with breast ductal carcinoma and in vitro overexpression leads to a change in the mode of breast cancer cell invasion through LM-rich matrices. 38 LaNt α31 is also transiently upregulated during re-epithelialization of ex vivo corneal burn wounds and in limbal stem cell activation assays.…”

Laminin Polymerization and Inherited Disease: Lessons From Genetics

“…These fragments contain "perfect" LN domains that are likely to compete for binding sites (with reduced potency compared with netrin-4). One LAMA3-derived alternative splice isoform, Laminin N terminus α31 (LaNt α31) has widespread expression in human tissues (Troughton et al, 2020b), is upregulated during wounding and corneal limbal stem cell activation (Barrera et al, 2018) and emerging data indicate that it can modulate LM organization in vitro (Troughton et al, 2020a). In vivo overexpression is embryonic lethal during development with tissue defects that resemble LM network disruption phenotypes (Sugden et al, 2020).…”