Biology subjects

Hamill, K. J.

Publications and source records attributed to Hamill, K. J..

3 recordsLinked to original sources

bioRxiv2020

Laminin N-terminus α31 expression during development in an inducible-transgenic mouse model is lethal and causes a multitude of tissue-specific defects

Laminins are essential components of all basement membranes where they regulate an extensive array of tissue functions. Alternative splicing from the laminin 3 gene produces a non-laminin but netrin-like protein, Laminin N terminus 31 (LaNt 31). LaNt 31 is widely expressed in intact tissue and is upregulated in epithelial cancers and during wound healing. In vitro functional studies have shown that LaNt 31 can influence numerous aspects of epithelial cell behaviour via modifying matrix organisation, suggesting a new model of laminin auto-regulation. However, the function of this protein has not been established beyond the epithelium and it has never been studied in vivo. Here, a mouse transgenic line was generated using the ubiquitin C promoter to drive inducible expression of LaNt 31. When expression was induced at embryonic day 15.5, LaNt 31 transgenic animals were not viable at birth, exhibiting localised regions of erythema. Numerous striking defects were apparent histologically, including extra-vascular erythrocytes in multiple tissues, kidney epithelial detachment, tubular dilation, interstitial bleeding, and thickening of tubule basement membranes, disruption of the epidermal basal cell layer and of the hair follicle outer root sheath, and ~50% reduction of cell numbers in the liver associated with depletion of hematopoietic erythrocytic foci. These findings demonstrate that LaNt 31 can influence tissue morphogenesis during development. More broadly, these data provide the first in vivo evidence to support an emerging model of laminin self-regulation and provide a valuable model for onward investigation into this important area. Summary StatementExpression during development of Laminin N-terminus 31, a netrin-like laminin splice isoform, caused defects indicating basement membrane disruption in multiple tissues; providing the first in vivo evidence for laminin self-regulation.

cell biology↗

bioRxiv2020

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

Laminin N-terminus 31 (LaNt 31) is an alternative splice isoform derived from the laminin 3 gene. The LaNt 31 protein is enriched around the terminal duct lobular units in normal breast tissue. In the skin and cornea the protein influences epithelial cell migration and tissue remodelling. However, LaNt 31 has never been investigated in a tumour environment. Here we analysed LaNt 31 in invasive ductal carcinoma and determined its contribution to breast carcinoma invasion. LaNt 31 expression and distribution were analysed by immunohistochemistry in human breast tissue biopsy sections and tissue microarrays covering 232 breast cancer samples. This analysis revealed LaNt 31 to be upregulated in 56 % of invasive ductal carcinoma specimens compared with matched normal tissue, and further increased in nodal metastasis compared with the tumour mass in 45 % of samples. 65.8 % of triple negative cases displayed medium to high LaNt 31 expression. To study LaNt 31 function, an adenoviral system was used to induce expression in MCF-7 and MDA-MB-231 cells. Metabolic activity, 2D cell migration, and invasion into collagen hydrogels were not significantly different between LaNt 31 overexpressing cells and control treated cells. However, LaNt 31 overexpressing MDA-MB-231 cells displayed a striking change in their mode of invasion into laminin-containing Matrigel; changing from multicellular streaming to individual cellular-invasion. In agreement with these results, 66.7% of the tumours with the highest LaNt 31 expression were non-cohesive. Together these findings indicate that breast cancer-associated changes in LaNt 31 expression could directly contribute to tumour invasiveness, and that this little-studied protein may become a therapeutic target.

cancer biology↗

bioRxiv2020

Laminin N-terminus α31 protein distribution in adult human tissues

Laminin N terminus 31 (LaNt 31) is a netrin-like protein derived from alternative splicing of the laminin 3 gene. Although LaNt 31 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 3. These data revealed widespread LaNt 31 expression. In epithelial tissue, LaNt 31 was present in the basal layer of the epidermis, throughout the epithelium of the digestive tract, and much of the epithelium of the reproductive system. LaNt 31 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 31 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 being of particular note. Intriguingly, LaNt 31 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 31 may be functionally relevant in a wider range of tissue contexts than previously thought, and provides a valuable basis for investigation into this interesting protein.

cell biology↗