Rural Land Management and Kidney Health.

There is wide geographic variability in the prevalence of chronic kidney disease, and much of this variability is unexplained by known clinical risk determinants such as diabetes and hypertension. Additional factors contributing to this geographic variability include social determinants of kidney health, as well as genetic factors (ancestry) and non-genetic factors (the environment). Environmental nephrotoxins can accelerate the progression of kidney disease in some patients at risk. Examples of environmental nephrotoxins that have previously been associated with changes in glomerular filtration rate include chlorotriazine herbicides (e.g., atrazine) and trace metals (e.g., arsenic, cadmium, lead, and mercury). Land management practices influence the concentration of these nephrotoxins in our soil and water. In this review, we explore sustainable approaches to agriculture and the preservation of natural landscapes as land management practices that can optimize kidney health in a variety of communities.

Small heat shock protein alphaA-crystallin regulates epithelial sodium channel expression.

Integral membrane proteins are synthesized on the cytoplasmic face of the endoplasmic reticulum (ER). After being translocated or inserted into the ER, they fold and undergo post-translational modifications. Within the ER, proteins are also subjected to quality control checkpoints, during which misfolded proteins may be degraded by proteasomes via a process known as ER-associated degradation. Molecular chaperones, including the small heat shock protein alphaA-crystallin, have recently been shown to play a role in this process. We have now found that alphaA-crystallin is expressed in cultured mouse collecting duct cells, where apical Na(+) transport is mediated by epithelial Na(+) channels (ENaC). ENaC-mediated Na(+) currents in Xenopus oocytes were reduced by co-expression of alphaA-crystallin. This reduction in ENaC activity reflected a decrease in the number of channels expressed at the cell surface. Furthermore, we observed that the rate of ENaC delivery to the cell surface of Xenopus oocytes was significantly reduced by co-expression of alphaA-crystallin, whereas the rate of channel retrieval remained unchanged. We also observed that alphaA-crystallin and ENaC co-immunoprecipitate. These data are consistent with the hypothesis that small heat shock proteins recognize ENaC subunits at ER quality control checkpoints and can target ENaC subunits for ER-associated degradation.