Glomerulosclerosis is one of the hallmarks of end stage kidney disease and it is characterized by the replacement of the glomerular tissue with extracellular matrix components (mainly collagens) leading to the loss of functioning glomeruli. The goal of this grant is to investigate the molecular mechanisms that underlie the modulation of collagen turnover in injured glomeruli to devise more effective therapies to prevent glomerulosclerosis. Although many pathways have been implicated in both initiation and progression to glomerular fibrosis, we focus on the collagen binding receptor integrin ?1?1 (Itg?1?1). This receptor plays an anti-fibrotic action by recruiting and activating the tyrosine phosphatase TCPTP thus downregulating the phosphorylation of pro-fibrotic receptors, including the EGF receptor (EGFR). Moreover, Itg?1?1 negatively regulates collagen levels at both transcriptional and translational levels. Recently, we started to investigate the mechanisms whereby Itg?1?1 controls collagen synthesis at the nuclear level. As nuclear translocation and activation of many transcription factors and/or ribonucleoproteins are regulated by tyrosine phosphorylation, we analyzed the levels of tyrosine phosphorylated nuclear proteins in wild type and Itg?1KO mesangial cells to identify proteins tyrosine phosphorylated only in Itg?1KO cells. We identified the ribonucleoprotein Fused in Sarcoma (FUS) as a candidate. We show that in Itg?1KO mesangial cells, increased levels of total and tyrosine phosphorylated nuclear FUS are associated with increased collagen production and downregulation of FUS decreases collagen synthesis. Interestingly, FUS contains two tyrosines that can be phosphorylated by EGFR and dephosphorylated by TCPTP and the levels of nuclear FUS are associated with levels of activated EGFR. Based on these observations and the finding that FUS is upregulated in injured human and mouse kidneys, we propose that FUS is a positive regulator of collagen synthesis and plays a pro-fibrotic action in the course of glomerulosclerosis. We hypothesize that Itg?1?1 negatively regulates FUS tyrosine phosphorylation and function in an EGFR-dependent and - independent manner. Thus, Itg?1?1-mediated dephosphorylation of FUS represents an important, but previously undescribed mechanism to selectively reduce FUS activation and consequent progression to fibrosis.
The aims of this grant are designed to define the contribution of FUS to glomerular disease and to determine whether blocking its function is beneficial for the treatment of glomerulosclerosis.
In Aim 1 we will determine in vitro the mechanisms whereby FUS transcriptionally controls collagen production and determine whether inhibiting FUS ameliorates collagen synthesis.
In Aim 2 we will determine the role of FUS in the progression to glomerular injury using a genetic and pharmacological approach. We will investigate the response of wild type and Itg?1KO mice crossed with global FUSKO mice, as well as mice overexpressing wild type FUS or mutated FUS no longer able to translocate to the nucleus to glomerular injury. We will then translate the relevance of these findings to a more clinically relevant setting, by investigating the response to glomerular injury in wild type and Itg?1KO mice untreated or treated with newly generated cell-penetrating peptides able to prevent FUS nuclear translocation. Understanding how the ribonucleoprotein FUS controls collagen production in glomerulosclerosis and exploring the consequences of its inhibition based on innovative delivery of nuclear transport modifiers will offer an entirely novel approach for the treatment and, ideally, prevention of glomerulosclerosis.

Public Health Relevance

End stage kidney disease is a major cause of morbidity and mortality for Veterans. One of the hallmarks of end stage kidney disease is glomerulosclerosis, characterized by abnormal glomerular accumulation of extracellular matrix leading to the loss of functioning glomeruli. The goal of this VA Merit renewal is to understand the mechanisms that underlie the modulation of matrix turnover in injured glomeruli to devise more effective therapies to prevent glomerulosclerosis. We will focus on the matrix receptors integrins, especially integrin ?1?1. We show that this collagen receptor plays an anti-fibrotic role by negatively regulating tyrosine phosphorylation levels and consequent nuclear localization of the ribonucleoprotein Fused in Sarcoma (FUS). We also show that FUS promotes collagen transcription and its inhibition and/or downregulation reduces collagen synthesis. Thus, we propose that integrin ?1?1-mediated inhibition of FUS phosphorylation represents a novel mechanism to selectively reduce FUS activation and consequent progression to fibrosis.

National Institute of Health (NIH)
Veterans Affairs (VA)
Non-HHS Research Projects (I01)
Project #
Application #
Study Section
Nephrology (NEPH)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Veterans Health Administration
United States
Zip Code
Albertolle, Matthew E; Phan, Thanh T N; Pozzi, Ambra et al. (2018) Sulfenylation of Human Liver and Kidney Microsomal Cytochromes P450 and Other Drug-Metabolizing Enzymes as a Response to Redox Alteration. Mol Cell Proteomics 17:889-900
Sausville, Lindsay N; Gangadhariah, Mahesha H; Chiusa, Manuel et al. (2018) The Cytochrome P450 Slow Metabolizers CYP2C9*2 and CYP2C9*3 Directly Regulate Tumorigenesis via Reduced Epoxyeicosatrienoic Acid Production. Cancer Res 78:4865-4877
Brown, Kyle L; Banerjee, Surajit; Feigley, Andrew et al. (2018) Salt-bridge modulates differential calcium-mediated ligand binding to integrin ?1- and ?2-I domains. Sci Rep 8:2916
Borza, Corina M; Pozzi, Ambra; Plosa, Erin J (2018) Discoidin Domain Receptor 2, a Potential Therapeutic Target in Lung Fibrosis. Am J Respir Cell Mol Biol 59:277-278
Sausville, Lindsay N; Jones, Carissa C; Aldrich, Melinda C et al. (2017) Genetic variation in the eicosanoid pathway is associated with non-small-cell lung cancer (NSCLC) survival. PLoS One 12:e0180471
Albertolle, Matthew E; Kim, Donghak; Nagy, Leslie D et al. (2017) Heme-thiolate sulfenylation of human cytochrome P450 4A11 functions as a redox switch for catalytic inhibition. J Biol Chem 292:11230-11242
Borza, Corina M; Su, Yan; Tran, Truc-Linh et al. (2017) Discoidin domain receptor 1 kinase activity is required for regulating collagen IV synthesis. Matrix Biol 57-58:258-271
Kothiwale, Sandeepkumar; Borza, Corina; Pozzi, Ambra et al. (2017) Quantitative Structure-Activity Relationship Modeling of Kinase Selectivity Profiles. Molecules 22:
Mathew, Sijo; Palamuttam, Riya J; Mernaugh, Glenda et al. (2017) Talin regulates integrin ?1-dependent and -independent cell functions in ureteric bud development. Development 144:4148-4158
Williams, Ashley S; Trefts, Elijah; Lantier, Louise et al. (2017) Integrin-Linked Kinase Is Necessary for the Development of Diet-Induced Hepatic Insulin Resistance. Diabetes 66:325-334

Showing the most recent 10 out of 33 publications