A PAI-1 Mutant, PAI-1R, Slows Progression of Diabetic Nephropathy

Huang, Yufeng; Border, Wayne A.; Yu, Ling; Zhang, Jiandong; Lawrence, Daniel A.; Noble, Nancy A.

doi:10.1681/asn.2007040510

Cited by 73 publications

(114 citation statements)

References 38 publications

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“…SERPINE1 encodes plasminogen activator inhibitor 1 (PAI-1), which is present in trace amounts in healthy kidneys but increased in a wide variety of both acute and chronically diseased kidneys. Reduced PAI-1 activity has been shown to be protective for the development of albuminuria and glomerulosclerosis in experimental diabetes (36). Moreover, CCL20 is upregulated in patients with progressive IgA nephropathy (32).…”

Section: Discussionmentioning

confidence: 99%

α Actinin 4 (ACTN4) Regulates Glucocorticoid Receptor-mediated Transactivation and Transrepression in Podocytes

Zhao

Khurana

Charkraborty

et al. 2017

Journal of Biological Chemistry

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Edited by Xiao-Fan WangGlucocorticoids are a general class of steroids that possess renoprotective activity in glomeruli through their interaction with the glucocorticoid receptor. However, the mechanisms by which glucocorticoids ameliorate proteinuria and glomerular disease are not well understood. In this study, we demonstrated that ␣ actinin 4 (ACTN4), an actin-cross-linking protein known to coordinate cytoskeletal organization, interacts with the glucocorticoid receptor (GR) in the nucleus of human podocytes (HPCs), a key cell type in the glomerulus critical for kidney filtration function. The GR-ACTN4 complex enhances glucocorticoid response element (GRE)-driven reporter activity. Stable knockdown of ACTN4 by shRNA in HPCs significantly reduces dexamethasone-mediated induction of GR target genes and GRE-driven reporter activity without disrupting dexamethasone-induced nuclear translocation of GR. Synonymous mutations or protein expression losses in ACTN4 are associated with kidney diseases, including focal segmental glomerulosclerosis, characterized by proteinuria and podocyte injury. We found that focal segmental glomerulosclerosis-linked ACTN4 mutants lose their ability to bind liganded GR and support GRE-mediated transcriptional activity. Mechanistically, GR and ACTN4 interact in the nucleus of HPCs. Furthermore, disruption of the LXXLL nuclear receptor-interacting motif present in ACTN4 results in reduced GR interaction and dexamethasone-mediated transactivation of a GRE reporter while still maintaining its actin-binding activity. In contrast, an ACTN4 isoform, ACTN4 (Iso), that loses its actin-binding domain is still capable of potentiating a GRE reporter. Dexamethasone induces the recruitment of ACTN4 and GR to putative GREs in dexamethasone-transactivated promoters, SERPINE1, ANGPLT4, CCL20, and SAA1 as well as the NF-B (p65) binding sites on GR-transrepressed promoters such as IL-1␤, IL-6, and IL-8. Taken together, our data establish ACTN4 as a transcriptional co-regulator that modulates both dexamethasone-transactivated and -transrepressed genes in podocytes.

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Section: Discussionmentioning

confidence: 99%

α Actinin 4 (ACTN4) Regulates Glucocorticoid Receptor-mediated Transactivation and Transrepression in Podocytes

Zhao

Khurana

Charkraborty

et al. 2017

Journal of Biological Chemistry

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“…Total RNA (2 g) was reverse transcribed using the SuperScript III first-stand synthesis system for RT-PCR kit (Invitrogen). Real-time RT-PCR was performed using SYBR Green Dye I (Applied Biosystems, Foster City, CA) with the ABI 7900 Sequence Detection System (PE Applied Biosystems) as described previously (12). Samples were run as triplicates in separate tubes to permit quantification of the target gene normalized to GAPDH used for equal loading.…”

Section: Rna Preparation and Real-time Rt-pcr Assaymentioning

confidence: 99%

Receptor-dependent prorenin activation and induction of PAI-1 expression in vascular smooth muscle cells

Zhang

Noble

Border³

et al. 2008

American Journal of Physiology-Endocrinology and Metabolism

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Although elevated plasma prorenin levels are commonly found in diabetic patients and correlate with microvascular complications, the pathological role of these increases, if any, remains unclear. Prorenin/renin binding to the prorenin/renin receptor [(p)RR] enhances the efficiency of angiotensinogen cleavage by renin and unmasks prorenin catalytic activity. We asked whether plasma prorenin could be activated in local vascular tissue through receptor binding. Immunohistochemical staining showing localization of the (p)RR in the aorta to vascular smooth muscle cells (VSMCs). After cultured rat VSMCs were incubated with 10−7 M inactive prorenin, cultured supernatant acquired the ability to generate ANG I from angiotensinogen, indicating that prorenin had been activated. Activated prorenin facilitated angiotensin generation in cultured VSMCs when exogenous angiotensinogen was added. Small interfering RNA (siRNA) against the (p)RR blocked this activation and subsequent angiotensin generation. Prorenin alone induced dose- and time-dependent increases in mRNA and protein for the profibrotic molecule plasminogen activator inhibitor (PAI)-1, effects that were blocked by siRNA, but not by the ANG II receptor antagonist saralasin. When inactive prorenin and angiotensinogen were incubated with cells, PAI-1 mRNA increased a striking 54-fold, 8-fold higher than the increase seen with prorenin alone. PAI-1 protein increased 2.75-fold. These effects were blocked by treatment with siRNA + saralasin. We conclude that prorenin at high concentration binds the (p)RR on VSMCs and is activated. This activation leads to increased expression of PAI-1 via ANG II-independent and -dependent mechanisms. These data provide a mechanism by which elevated prorenin levels in diabetes may contribute to the progression of fibrotic disease.

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“…PAI-1 also plays a role in many physiologic processes, including angiogenesis, wound healing, and cell migration (2)(3)(4)(5)(6), and has been implicated in fibrotic diseases of the kidney and lung, and in tumor metastasis (7)(8)(9)(10)(11). More recently, PAI-1 has been linked to obesity and metabolic syndrome (12)(13)(14)(15)(16), and to the development of vascular diseases such as venous thrombosis and atherosclerosis (17)(18)(19).…”

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confidence: 99%

Characterization of a Novel Class of Polyphenolic Inhibitors of Plasminogen Activator Inhibitor-1

Cale

Warnock

et al. 2010

Journal of Biological Chemistry

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Plasminogen activator inhibitor type 1, (PAI-1) the primary inhibitor of the tissue-type (tPA) and urokinase-type (uPA) plasminogen activators, has been implicated in a wide range of pathological processes, making it an attractive target for pharmacologic inhibition. Currently available small-molecule inhibitors of PAI-1 bind with relatively low affinity and do not inactivate PAI-1 in the presence of its cofactor, vitronectin. To search for novel PAI-1 inhibitors with improved potencies and new mechanisms of action, we screened a library selected to provide a range of biological activities and structural diversity. Five potential PAI-1 inhibitors were identified, and all were polyphenolic compounds including two related, naturally occurring plant polyphenols that were structurally similar to compounds previously shown to provide cardiovascular benefit in vivo. Unique second generation compounds were synthesized and characterized, and several showed IC 50 values for PAI-1 between 10 and 200 nM. This represents an enhanced potency of 10 -1000-fold over previously reported PAI-1 inactivators. Inhibition of PAI-1 by these compounds was reversible, and their primary mechanism of action was to block the initial association of PAI-1 with a protease. Consistent with this mechanism and in contrast to previously described PAI-1 inactivators, these compounds inactivate PAI-1 in the presence of vitronectin. Two of the compounds showed efficacy in ex vivo plasma and one blocked PAI-1 activity in vivo in mice. These data describe a novel family of high affinity PAI-1-inactivating compounds with improved characteristics and in vivo efficacy, and suggest that the known cardiovascular benefits of dietary polyphenols may derive in part from their inactivation of PAI-1. Plasminogen activator inhibitor type 1 (PAI-1)3 is the primary physiologic inhibitor of uPA and tPA with a well characterized role in fibrinolysis (1). PAI-1 also plays a role in many physiologic processes, including angiogenesis, wound healing, and cell migration (2-6), and has been implicated in fibrotic diseases of the kidney and lung, and in tumor metastasis (7-11). More recently, PAI-1 has been linked to obesity and metabolic syndrome (12-16), and to the development of vascular diseases such as venous thrombosis and atherosclerosis (17)(18)(19). The prospect that PAI-1 may play a direct role in the early development of a variety of diseases has made it an attractive target for drug development (20,21). However, the structural complexity of PAI-1 has made the identification and development of PAI-1 inhibitors challenging. This is due in part to the metastable structure of PAI-1, which can adopt several different conformations, including active, latent, cleaved, and protease complexed (1). These different forms of PAI-1 provide conformational control of PAI-1 interactions and dictate its localization to either matrix or the cell surface and control its activity in cell signaling events (22, 23).Active PAI-1 inhibits protease targets and is associated with vitron...

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A PAI-1 Mutant, PAI-1R, Slows Progression of Diabetic Nephropathy

Cited by 73 publications

References 38 publications

α Actinin 4 (ACTN4) Regulates Glucocorticoid Receptor-mediated Transactivation and Transrepression in Podocytes

α Actinin 4 (ACTN4) Regulates Glucocorticoid Receptor-mediated Transactivation and Transrepression in Podocytes

Receptor-dependent prorenin activation and induction of PAI-1 expression in vascular smooth muscle cells

Characterization of a Novel Class of Polyphenolic Inhibitors of Plasminogen Activator Inhibitor-1

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