Holzman, L. B. | Search bioRxiv

bioRxiv2020

HGF-induced activation of NEPHRIN and NEPH1 serves as a novel mechanism for recovery of podocytes from injury

When activated, slit diaphragm proteins NEPHRIN and NEPH1 enable signaling pathways leading to podocyte actin cytoskeleton reorganization, which is critical for podocyte recovery from injury. However, the mechanisms through which these proteins are activated remain unknown. This study presents a novel concept showing ligand-induced activation of NEPHRIN and NEPH1. We first identified phosphatase SHP-2, which directly dephosphorylated these proteins. We next identified HGF, a known SHP-2 modulator, as a rapid inducer of NEPHRIN and NEPH1 phosphorylation. Using baculovirus expressed recombinant purified proteins, SPR (surface plasma resonance), molecular modeling and peptide binding approaches, we show that HGF directly binds NEPHRIN and NEPH1 extracellular domains. Further, using cultured podocytes and Drosophila nephrocytes, we demonstrate that while HGF treatment repaired injured podocytes, the addition of inhibitory NEPH1 or NEPHRIN peptides blocked HGF-induced recovery. Overall, this study shows novel activation and deactivation mechanisms for NEPHRIN and NEPH1 that are required for their function.

cell biology↗

bioRxiv2018

Redefining Nephrotic Syndrome in Molecular Terms: Outcome-associated molecular clusters and patient stratification with noninvasive surrogate biomarkers

A tissue transcriptome driven classification of nephrotic syndrome patients identified a high risk group of patients with TNF activation and established a non-invasive marker panel for pathway activity assessment paving the way towards precision medicine trials in NS.\n\nAbstractNephrotic syndrome from primary glomerular diseases can lead to chronic kidney disease (CKD) and/or end-stage renal disease (ESRD). Conventional diagnoses using a combination of clinical presentation and descriptive biopsy information do not accurately predict risk for progression in patients with nephrotic syndrome, which complicates disease management. To address this challenge, a transcriptome-driven approach was used to classify patients with minimal change disease and focal segmental glomerulosclerosis in the Nephrotic Syndrome Study Network (NEPTUNE). Transcriptome-based classification revealed a group of patients at risk for disease progression. High risk patients had a transcriptome profile consistent with TNF activation. Non-invasive urine biomarkers TIMP1 and CCL2 (MCP1), which are causally downstream of TNF, accurately predicted TNF activation in the NEPTUNE cohort setting the stage for patient stratification approaches and precision medicine in kidney disease.

systems biology↗