Biology subjects

Sarro, E.

Publications and source records attributed to Sarro, E..

4 recordsLinked to original sources

bioRxiv2025

TMEM9 and SEC22B interact with ClC-5 to shape renal proximal tubule function and Dent's Disease type I pathogenesis

Cl-/H+ antiporter ClC-5 is a key regulator of renal proximal tubule function, primarily by controlling endosomal acidification. Loss-of-function mutations in ClC-5 cause Dents Disease type 1 (DD1), a rare renal tubulopathy that progresses to kidney failure with varying severity. To understand the specific mechanisms linking ClC-5 loss-of-function with DD1 phenotypic heterogeneity, three ClC-5 pathogenic mutations (I524K, E527D and V523{Delta}) were investigated using renal proximal tubule epithelial cell lines. We have identified distinct intracellular retention patterns of these ClC-5 mutants, all leading to altered endolysosomal pH and disrupted secretory pathway organization. Through an interactome analysis, we have uncovered several ClC-5 partners including TMEM9, which interacted with all ClC-5 forms. TMEM9 knockdown (KD) recapitulated key DD1 characteristics, like defective endocytosis and epithelial dedifferentiation, but paradoxically enhanced endosomal acidification. The secretory pathway was also altered in cells lacking TMEM9 (e.g. enlarged endosomes, and fragmented Golgi apparatus). A similar phenotype was observed in cells depleted of SEC22B; an R-SNARE that we have found to specifically interact with wild-type ClC-5, but not the mutants. Notably, its deletion impaired ClC-5 trafficking, causing its retention at the Golgi and endosomes. Altogether, our findings highlight the relevance of TMEM9 and SEC22B in ClC-5 function, suggesting them as DD1 pathophysiology modifiers.

cell biology↗

bioRxiv2020

Global gene-expression analysis reveals the molecular processes underlying ClC-5 loss-of-function in novel Dent Disease 1 cellular models

Dent disease 1 (DD1) is a rare X-linked renal proximal tubulopathy characterized by low molecular weight proteinuria (LMWP) and variable degree of hypercalciuria, nephrocalcinosis and/or nephrolithiasis with progression to chronic kidney disease (CKD). Although loss-of-function mutations in the gene CLCN5 encoding the electrogenic Cl-/H+ antiporter ClC-5, which impair endocytic uptake in proximal tubule cells, cause the disease, there is poor genotype-phenotype correlation and their contribution to proximal tubule dysfunction remains unclear. Here, in order to discover the mechanisms leading to proximal tubule dysfunction due to ClC-5 loss-of-function, we have generated and characterized new human cellular models of DD1 by silencing CLCN5 and introducing the ClC-5 pathogenic mutants V523del, E527D and I524K into the human proximal tubule-derived cell line RPTEC/TERT1. Depletion of CLCN5 or expression of mutant ClC-5 impairs albumin endocytosis, increases substrate adhesion and decreases collective migration, which correlates with a less differentiated epithelial phenotype. Interestingly, although all conditions compromised the endocytic capacity in a similar way, their impact on gene expression profiles was different. Our DNA microarray studies show that ClC-5 silencing or mutant re-introduction alter pathways related to nephron development, anion homeostasis, organic acid transport, extracellular matrix organization and cell migration, compared to control cells. Cells carrying the V523del ClC-5 mutation show the largest differences in gene expression vs WT cells, which is in agreement with the more aggressive clinical phenotype observed in some DD1 patients. Overall, this work emphasizes the use of human proximal tubule derived cell models to identify the molecular processes underlying ClC-5 deficiency.

pathology↗

bioRxiv2019

Adverse caregiving in infancy blunts neural processing of the mother: Translating across species

The roots of psychopathology frequently take shape during infancy in the context of parent-infant interactions and adversity. Yet, neurobiological mechanisms linking these processes during infancy remain elusive. Here, using responses to attachment figures among infants who experienced adversity as a benchmark, we assessed rat pup cortical Local Field Potentials (LFP) and behaviors exposed to adversity in response to maternal rough and nurturing handling by examining its impact on pup separation-reunion with the mother. We show that during adversity, pup cortical LFP dynamic range decreased during nurturing maternal behaviors, but was minimally impacted by rough handling. During reunion, adversity-experiencing pups showed aberrant interactions with mother and blunted cortical LFP. Blocking pup stress hormone during either adversity or reunion restored typical behavior, LFP power, and cross-frequency coupling. This translational approach suggests adversity-rearing produces a stress-induced aberrant neurobehavioral processing of the mother, which can be used as an early biomarker of later-life pathology.

neuroscience↗

bioRxiv2018

Cyclophilins A and B Oppositely Regulate Renal Tubular Epithelial Phenotype

Cyclophilins (Cyp) are peptidil-prolyl-isomerases and the intracellular receptors for the immunosuppressant Cyclosporine-A (CsA), which produces epithelial-mesenchymal-transition (EMT) and renal tubule-interstitial fibrosis. Since CsA inhibits Cyp enzymatic activity, we hypothesized that Cyp could be involved in EMT and fibrosis. Here, we demonstrate that CypB is a critical regulator of tubule epithelial cell plasticity on the basis that: i) CypB silencing caused epithelial differentiation in proximal tubule-derived HK-2 cells, ii) CypB silencing prevented TGF{beta}-induced EMT in HK-2, and iii) CypB knockdown mice exhibited reduced UUO-induced inflammation and kidney fibrosis. By contrast, silencing of CypA induces a more undifferentiated phenotype and favors TGF{beta} effects. EMT mediators Slug and Snail were up-regulated in CypA-silenced cells, while in CypB silencing, Slug, but not Snail, was down-regulated; thus, reinforcing the role of Slug in kidney fibrosis. CypA regulates Slug through its PPIase activity whereas CypB depends on its ER location, where interacts with calreticulin, a calcium modulator which is involved in TGF{beta} signaling. In conclusion, this work uncovers new roles for CypA and CypB in modulating proximal tubular cell plasticity.

molecular biology↗