The polarized expression of Na+,K+-ATPase in epithelia depends on the association between beta-subunits located in neighboring cells

The polarized distribution of Na+,K+-ATPase plays a paramount physiological role, because either directly or through coupling with co- and countertransporters, it is responsible for the net movement of, for example, glucose, amino acids, Ca2+, K+, Cl-, and CO3H- across the whole epithelium. We report here that the beta-subunit is a key factor in the polarized distribution of this enzyme. 1) Madin-Darby canine kidney (MDCK) cells (epithelial from dog kidney) express the Na+,K+-ATPase over the lateral side, but not on the basal and apical domains, as if the contact with a neighboring cell were crucial for the specific membrane location of this enzyme. 2) MDCK cells cocultured with other epithelial types (derived from human, cat, dog, pig, monkey, rabbit, mouse, hamster, and rat) express the enzyme in all (100%) homotypic MDCK/MDCK borders but rarely in heterotypic ones. 3) Although MDCK cells never express Na+,K+-ATPase at contacts with Chinese hamster ovary (CHO) cells, they do when CHO cells are transfected with beta(1)-subunit from the dog kidney (CHO-beta). 4) This may be attributed to the adhesive property of the beta(1)-subunit, because an aggregation assay using CHO (mock-transfected) and CHO-beta cells shows that the expression of dog beta(1)-subunit in the plasma membrane does increase adhesiveness. 5) This adhesiveness does not involve adherens or tight junctions. 6) Transfection of beta(1)-subunit forces CHO-beta cells to coexpress endogenous a-subunit. Together, our results indicate that MDCK cells express Na+,K+-ATPase at a given border provided the contacting cell expresses the dog P,-subunit. The cell-cell interaction thus established would suffice to account for the polarized expression and positioning of Na+,K+-ATPase in epithelial cells

Teaching Undergraduate Students about Cultural and Linguistic Diversity: Assessment and Pedagogical Challenges

Purpose: Diverse undergraduate students can play a critical role in increasing the number of culturally competent clinicians in the future. However, exploring how these students develop cultural and linguistic awareness is crucial. This study examined the development and assessment of cultural and linguistic awareness among a diverse group of undergraduate students who completed a dedicated course on cultural and linguistic diversity in communication disorders. Method: We conducted quantitative and qualitative analyses to evaluate student growth. Ninety-seven undergraduate students from a public Hispanic-Serving Institution completed an adaptation of the ASHA\u27s Cultural Competence Checklist: Personal Reflection at the beginning and end of a 16-week dedicated course. We analyzed the item responses using a paired t-test, and factor analyses were run to explore the potential presence of underlying constructs. We also analyzed open-ended students\u27 reflections at the end of the semester. Results: Students exhibited significant gains in cultural awareness. The exploratory factor analyses of the Personal Reflection responses at the beginning and end of the semester resulted in similar percentages of explained variance but by different item groupings. Students\u27 reflections converged into two broad categories: (1) topics related to the course content and (2) student comments reflecting internal processes. Conclusions: A dedicated course with relevant content may positively influence growth in cultural awareness in diverse undergraduate students. We discuss pedagogical challenges and potential mitigating approaches to develop and evaluate cultural awareness. Overall, our study offers insights into the development of cultural understanding among diverse undergraduate students and provides actionable recommendations for promoting a more inclusive and culturally responsive learning environment

Influence of Cardiac Glycosides and Prostaglandins on the Physiology of Epithelial Cells

Epithelial cells play a major role in animal and human homeostasis because they selectively regulate the exchange of solutes between two given media, such as blood or urine. Cardiac glycosides (CG) are a group of highly toxic compounds whose best therapeutic known effect is on heart, although recent evidence has shown that it exerts a wide range of physiological effects on cells and tissues other than the heart. Prostaglandins, on the other hand, are a group of lipids that produce diverse physiological and pathological effects among which inflammation stands out. In this chapter, we describe that cardiac glycosides modulate key features of epithelial cell physiology, including cell-cell contact junctional complexes, cilliogenesis, and gap junction-mediated intercellular communication (GJIC) in epithelial cells. Prostaglandin PGE2 also modulates GJIC through a different signaling pathway. In addition, we describe that CG induce paracrine release of prostaglandin PGE2, which in turn modulates GJIC by itself

Brain microvessel endothelial cells in tissue culture: A model for study of blood-brain barrier permeability

Endothelial cells were prepared from bovine brain microvessels and grown in tissue culture. They contained factor VIII/von Willebrand antigen, the most specific marker available for determination of the endothelial origin of cells in culture. The cultured cells formed complex tight junctions and contained few pinocytotic vessels. These properties are responsible for formation of the blood-brain barrier in vivo. When monolayers of the endothelial cells were exposed briefly to a calcium-free solution or treated with 1.6 M arabinose, distinctive morphological changes occurred in the intercellular contacts. In either case, a normal structure was reestablished following return to control medium. To assess the effect of these treatments on transcellular permeability, we measured the movement of sucrose labeled with carbon 14 across a monolayer of endothelial cells cultured on a collagen-coated nylon mesh. Removal of external calcium increased the rate of sucrose movement by 120%; the arabinose treatment increased transcellular flux by 40%.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50304/1/410140403_ftp.pd