Developing an in vitro model of CKD-MBD induced αKlotho suppression

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Julia Hum Ph.D

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Medicine and Health Sciences


Chronic Kidney Disease (CKD) affects approximately 1 in 10 Americans. Diabetic nephropathy is also associated with the development of chronic kidney disease-mineral bone disorder (CKD-MBD). CKD-MBD disrupts the normal bone-kidney endocrine axis responsible for regulating mineral metabolism, and hyperphosphatemia develops in late stage disease. Important clinical hallmarks of the CKD-MBD progression include elevated bioactive bone derived Fibroblast growth factor-23 (FGF23) and suppression of FGF23’s co-receptor, αKlotho (αKL). In healthy individuals the hormone FGF23, primarily produced by bone, and αKL aid in maintaining normal phosphate and vitamin D homeostasis. It is currently unknown what drives the suppression of αKL expression, however increasing αKL expression in CKD-MBD models is being investigated as a novel therapeutic. Our study sought to develop a novel in vitro model of one of the clinical hallmarks of the progression of CKD-MBD, αKL suppression, to investigate both possible stimuli of its repression and downstream signaling events. The Human Embryonic Kidney (HEK) cell line was used to determine if changes in fluid shear stress, similar to those that occur in diabetic nephropathy, could lead to reduced αKL expression. HEK cells were plated and exposed to oscillatory fluid shear stress (OFSS) for intervals between 0-60 min to examine protein expression or 0-2 hours to assess gene expression. HEK cells were sensitive to mechanical stimulation as pathways including increased ERK phosphorylation occurred in response to OFSS. In response to longer bouts of OFSS αKL expression was reduced. Dramatic changes in fluid shear stress may serve as a stimulus for reduced αKL expression in CKD-MBD. Further studies are underway to investigate downstream signaling events related to αKL suppression. Understanding both the stimuli of αKL suppression and related downstream signaling events could provide novel therapeutic targets for the treatment of CKD-MBD.


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