Deletion of Cdh-16 Ksp-cadherin leads to a developmental delay in the ability to maximally concentrate urine in mouse

Ksp-cadherin (Cadherin-16) is an atypical member of the cadherin superfamily of cell adhesion molecules that is ubiquitously expressed on the basolateral membrane of epithelial cells lining the nephron and the collecting system of the mammalian kidney. The principal aim of the present study was to determine if Ksp-cadherin played a critical role in the development and maintenance of the adult mammalian kidney by generating and evaluating a mouse line deficient in Ksp-cadherin. Ksp-null mutant animals were viable and fertile, and kidneys from both neonates and adults showed no evidence of structural abnormalities. Immunolocalization and Western analyses of Na/K-ATPase and E-cadherin indicated that Ksp-cadherin is not essential for either the genesis or maintenance of the polarized tubular epithelial phenotype. Moreover, E-cadherin expression was not altered to compensate for Ksp-cadherin loss. Plasma electrolytes, total CO2, BUN, and creatinine levels were also unaffected by Ksp-cadherin deficiency. However, a subtle but significant developmental delay in the ability to maximally concentrate urine was detected in Ksp-null mice. Expression analysis of the principal proteins involved in the generation of the cortico-medullary osmotic gradient and the resultant movement of water identified misexpression of Aquaporin-2 in the inner medullary collecting duct as the possible cause for the inability of young adult Ksp-cadherin deficient animals to maximally concentrate their urine. In conclusion, Ksp-cadherin is not required for normal kidney development but its absence leads to a developmental delay in maximal urinary concentrating ability.

New imaging tools to measure nephron number in vivo: opportunities for developmental nephrology

The mammalian kidney is a complex organ, requiring the concerted function of up to millions of nephrons. The number of nephrons is constant after nephrogenesis during development, and nephron loss over a life span can lead to susceptibility to acute or chronic kidney disease. New technologies are under development to count individual nephrons in the kidney in vivo. This review outlines these technologies and highlights their relevance to studies of human renal development and disease.

Single Cell Profiling Reveals Sex, Lineage and Regional Diversity in the Mouse Kidney

SummaryChronic kidney disease affects 10% of the population with notable differences in ethnic and sex-related susceptibility to kidney injury and disease. Kidney dysfunction leads to significant morbidity and mortality, and chronic disease in other organ systems. A mouse organ-centered understanding underlies rapid progress in human disease modeling, and cellular approaches to repair damaged systems. To enhance an understanding of the mammalian kidney, we combined anatomy-guided single cell RNA sequencing of the adult male and female mouse kidney with in situ expression studies and cell lineage tracing. These studies reveal cell diversity and marked sex differences, distinct organization and cell composition of nephrons dependent on the time of nephron specification, and lineage convergence, in which contiguous functionally-related cell types are specified from nephron and collecting system progenitor populations. A searchable database integrating findings to highlight gene-cell relationships in a normal anatomical framework will facilitate study of the mammalian kidney.