Defective cell adhesion function of solute transporter, SLC4A11, in endothelial corneal dystrophies

Corneal endothelial cell (CEnC) loss is often associated with blinding endothelial corneal dystrophies: dominantly inherited, common (5%) Fuchs endothelial corneal dystrophy (FECD) and recessive, rare congenital hereditary endothelial dystrophy (CHED). Mutations of SLC4A11, an abundant corneal solute transporter, cause CHED and some cases of FECD. The link between defective SLC4A11 solute transport function and CEnC loss is, however, unclear. Cell adhesion assays using SLC4A11-transfected HEK293 cells and primary human CEnC revealed that SLC4A11 promotes adhesion to components of Descemet’s membrane (DM), the basement membrane layer to which CEnC bind. An antibody against SLC4A11 extracellular loop 3 (EL3) suppressed cell adhesion, identifying EL3 as the DM binding site. Earlier studies showed that some SLC4A11 mutations cause FECD and CHED by impairing solute transport activity or cell surface trafficking. Without affecting these functions, FECD-causing mutations in SLC4A11-EL3 compromised cell adhesion capacity. In an energy-minimized SLC4A11-EL3 three-dimensional model, these mutations cluster and are buried within EL3 structure. A GST fusion protein of SLC4A11-EL3 interacts with principal DM protein, COL8A2, as identified by mass spectrometry. Engineered SLC4A11-EL3-containing protein, STIC (SLC4A11-EL3 Transmembrane-GPA Integrated Chimera), promotes cell adhesion in transfected HEK293 cells and primary human CEnC, confirming the cell adhesion role of EL3. Taken together, the data suggest that SLC4A11 directly binds DM to serve as a cell adhesion molecule (CAM). These data further suggest that cell adhesion defects contribute to FECD and CHED pathology. Observations with STIC point toward a new therapeutic direction in these diseases: replacement of lost cell adhesion capacity.

Revisiting the generalized scaling law for adhesion: role of compliance and extension to progressive failure

The generalized scaling law for adhesion is revisited, based on the classical fracture mechanics approach, leading to a revised scaling law that accounts for the role of load train compliance and extends to progressive failure modes.

An Extracellular Serine/Threonine-Rich Protein from Lactobacillus plantarum NCIMB 8826 Is a Novel Aggregation-Promoting Factor with Affinity to Mucin

ABSTRACTAutoaggregation in lactic acid bacteria is directly related to the production of certain extracellular proteins, notably, aggregation-promoting factors (APFs). Production of aggregation-promoting factors confers beneficial traits to probiotic-producing strains, contributing to their fitness for the intestinal environment. Furthermore, coaggregation with pathogens has been proposed to be a beneficial mechanism in probiotic lactic acid bacteria. This mechanism would limit attachment of the pathogen to the gut mucosa, favoring its removal by the human immune system. In the present paper, we have characterized a novel aggregation-promoting factor inLactobacillus plantarum. A mutant with a knockout of the D1 gene showed loss of its autoaggregative phenotype and a decreased ability to bind to mucin, indicating an adhesion role of this protein. In addition, heterologous production of the D1 protein or an internal fragment of the protein, characterized by its abundance in serine/threonine, strongly induced autoaggregation inLactococcus lactis. This result strongly suggested that this internal fragment is responsible for the bioactivity of D1 as an APF. To our knowledge, this is the first report on a gene coding for an aggregation-promoting factor inLb. plantarum.