Introduction of DNA enzyme for Egr-1 into tubulointerstitial fibroblasts by electroporation reduced interstitial alpha-smooth muscle actin expression and fibrosis in unilateral ureteral obstruction (UUO) rats

Pioglitazone Protects Tubular Epithelial Cells during Kidney Fibrosis by Attenuating miRNA Dysregulation and Autophagy Dysfunction Induced by TGF-β

Excessive renal TGF-β production and pro-fibrotic miRNAs are important drivers of kidney fibrosis that lack any efficient treatment. Dysfunctional autophagy might play an important role in the pathogenesis. We aimed to study the yet unknown effects of peroxisome proliferator-activated receptor-γ (PPARγ) agonist pioglitazone (Pio) on renal autophagy and miRNA dysregulation during fibrosis. Mouse primary tubular epithelial cells (PTEC) were isolated, pre-treated with 5 µM pioglitazone, and then stimulated with 10 ng/mL TGF-β1 for 24 h. Male 10-week-old C57Bl6 control (CTL) and TGF-β overexpressing mice were fed with regular chow (TGF) or Pio-containing chow (20 mg/kg/day) for 5 weeks (TGF + Pio). PTEC and kidneys were evaluated for mRNA and protein expression. In PTEC, pioglitazone attenuated (p < 0.05) the TGF-β-induced up-regulation of Col1a1 (1.4-fold), Tgfb1 (2.2-fold), Ctgf (1.5-fold), Egr2 (2.5-fold) mRNAs, miR-130a (1.6-fold), and miR-199a (1.5-fold), inhibited epithelial-to-mesenchymal transition, and rescued autophagy function. In TGF mice, pioglitazone greatly improved kidney fibrosis and related dysfunctional autophagy (increased LC3-II/I ratio and reduced SQSTM1 protein content (p < 0.05)). These were accompanied by 5-fold, 3-fold, 12-fold, and 2-fold suppression (p < 0.05) of renal Ccl2, Il6, C3, and Lgals3 mRNA expression, respectively. Our results implicate that pioglitazone counteracts multiple pro-fibrotic processes in the kidney, including autophagy dysfunction and miRNA dysregulation.

Iguratimod attenuated fibrosis in systemic sclerosis via targeting early growth response 1 expression

BACKGROUND

The early growth response 1 (EGR1) is a central transcription factor involved in systemic sclerosis (SSc) pathogenesis. Iguratimod is a synthesized anti-rheumatic disease-modifying drug, which shows drastic inhibition to EGR1 expression in B cells. This study is aiming to investigate the anti-fibrotic effect of iguratimod in SSc.

METHODS

EGR1 was detected by immunofluorescence staining real-time PCR or western blot. Iguratimod was applied in EGR1 overexpressed or knockdown human dermal fibroblast, bleomycin pre-treated mice, tight skin 1 mice, and SSc skin xenografts. RNA sequencing was performed in cultured fibroblast and xenografts to identify the iguratimod regulated genes.

RESULTS

EGR1 overexpressed predominantly in non-immune cells of SSc patients. Iguratimod reduced EGR1 expression in fibroblasts and neutralized changes of EGR1 response genes regulated by TGFβ. The extracellular matrix (ECM) production and activation of fibroblasts were attenuated by iguratimod while EGR1 overexpression reversed this effect of iguratimod. Iguratimod ameliorated the skin fibrosis induced by bleomycin and hypodermal fibrosis in TSK-1 mice. Decreasing in the collagen content as well as the density of EGR1 or TGFβ positive fibroblasts of skin xenografts from naïve SSc patients was observed after local treatment of iguratimod.

CONCLUSION

Targeting EGR1 expression is a probable underlying mechanism for the anti-fibrotic effect of iguratimod.

Klotho prevents epithelial-mesenchymal transition through Egr-1 downregulation in diabetic kidney disease

INTRODUCTION

As a key event leading to tubulointerstitial fibrosis in diabetic kidney disease (DKD), epithelial-mesenchymal transition (EMT) has drawn increasing attention from researchers. The antiaging protein Klotho attenuates renal fibrosis in part by inhibiting ERK1/2 signaling in DKD. Early growth response factor 1 (Egr-1), which is activated mainly by ERK1/2, has been shown to play an important role in EMT. However, whether Klotho prevents EMT by inhibiting ERK1/2-dependent Egr-1 expression in DKD is unclear.The aim of this study was to investigate whether Klotho prevents EMT through Egr-1 downregulation by inhibiting the ERK1/2 signaling pathway in DKD.

RESEARCH DESIGN AND METHODS

Male C57BL/6J mice fed an high-fat diet for 4 weeks received 120 mg/kg streptozotocin (STZ), which was injected intraperitoneally. Klotho and Egr-1 expression was detected in the renal cortices of these mice on their sacrifice at 6 and 12 weeks after STZ treatment. In In vitro studies, we incubated HK2 cells under high-glucose (HG) or transforming growth factor-β1 (TGF-β1) conditions to mimic DKD. We then transfected the cells with an Klotho-containing plasmid, Klotho small interfering RNA.

RESULTS

Klotho expression was significantly decreased in the renal cortices of mice with diabetes mellitus (DM) compared with the renal cortices of control mice at 6 weeks after treatment and even more significantly decreased at 12 weeks. In contrast, Egr-1 expression was significantly increased in mice with DM compared with control mice only at 12 weeks. We also found that Klotho overexpression downregulated Egr-1 expression and the (p-ERK1/2):(ERK1/2) ratio in HG-treated or TGF-β1-treated HK2 cells. Conversely, Klotho silencing upregulated Egr-1 expression and the (p-ERK1/2):(ERK1/2) ratio in HG-treated or TGF-β1-treated HK2 cells. Moreover, the effects of si-Klotho were abolished by the ERK1/2 inhibitor PD98059.

CONCLUSIONS

Klotho prevents EMT during DKD progression, an effect that has been partially attributed to Egr-1 downregulation mediated by ERK1/2 signaling pathway inhibition.

Precision gene editing technology and applications in nephrology

The expanding field of precision gene editing is empowering researchers to directly modify DNA. Gene editing is made possible using synonymous technologies: a DNA-binding platform to molecularly locate user-selected genomic sequences and an associated biochemical activity that serves as a functional editor. The advent of accessible DNA-targeting molecular systems, such as zinc-finger nucleases, transcription activator-like effectors (TALEs) and CRISPR-Cas9 gene editing systems, has unlocked the ability to target nearly any DNA sequence with nucleotide-level precision. Progress has also been made in harnessing endogenous DNA repair machineries, such as non-homologous end joining, homology-directed repair and microhomology-mediated end joining, to functionally manipulate genetic sequences. As understanding of how DNA damage results in deletions, insertions and modifications increases, the genome becomes more predictably mutable. DNA-binding platforms such as TALEs and CRISPR can also be used to make locus-specific epigenetic changes and to transcriptionally enhance or suppress genes. Although many challenges remain, the application of precision gene editing technology in the field of nephrology has enabled the generation of new animal models of disease as well as advances in the development of novel therapeutic approaches such as gene therapy and xenotransplantation.

Podocyte histone deacetylase activity regulates murine and human glomerular diseases

We identified 2 genes, histone deacetylase 1 (HDAC1) and HDAC2, contributing to the pathogenesis of proteinuric kidney diseases, the leading cause of end-stage kidney disease. mRNA expression profiling from proteinuric mouse glomeruli was linked to Connectivity Map databases, identifying HDAC1 and HDAC2 with the differentially expressed gene set reversible by HDAC inhibitors. In numerous progressive glomerular disease models, treatment with valproic acid (a class I HDAC inhibitor) or SAHA (a pan-HDAC inhibitor) mitigated the degree of proteinuria and glomerulosclerosis, leading to a striking increase in survival. Podocyte HDAC1 and HDAC2 activities were increased in mice podocytopathy models, and podocyte-associated Hdac1 and Hdac2 genetic ablation improved proteinuria and glomerulosclerosis. Podocyte early growth response 1 (EGR1) was increased in proteinuric patients and mice in an HDAC1- and HDAC2-dependent manner. Loss of EGR1 in mice reduced proteinuria and glomerulosclerosis. Longitudinal analysis of the multicenter Veterans Aging Cohort Study demonstrated a 30% reduction in mean annual loss of estimated glomerular filtration rate, and this effect was more pronounced in proteinuric patients receiving valproic acid. These results strongly suggest that inhibition of HDAC1 and HDAC2 activities may suppress the progression of human proteinuric kidney diseases through the regulation of EGR1.

Targeting TGF-β Signaling in Kidney Fibrosis

Renal fibrosis is the final common pathway of numerous progressive kidney diseases, and transforming growth factor-β (TGF-β) has an important role in tissue fibrosis by up-regulating matrix protein synthesis, inhibiting matrix degradation, and altering cell-cell interaction. Many strategies targeting TGF-β, including inhibition of production, activation, binding to the receptor, and intracellular signaling, have been developed. Some of them were examined in clinical studies against kidney fibrosis, and some are applied to other fibrotic diseases or cancer. Here, I review the approaches targeting TGF-β signaling in kidney fibrosis.

Metformin Improves Epithelial-to-Mesenchymal Transition Induced by TGF-β1 in Renal Tubular Epithelial NRK-52E Cells via Inhibiting Egr-1

The early growth response- (Egr-) 1 has been found to play a key role in organ fibrosis. Metformin has been shown to be effective in attenuating renal tubular epithelial-to-mesenchymal transition (EMT), which is involved in renal fibrosis. However, it is unknown whether metformin improves EMT via inhibiting Egr-1. In this study, rat renal tubular epithelial (NRK-52 E) cells, treated by transforming growth factor- (TGF-) β1 of 10 ng/ml with or without metformin of 1 mmol/l, were transfected by siEgr-1 or M61-Egr-1 plasmids to knock down or overexpress Egr-1, respectively. The gene and protein expressions of E-cadherin, α-SMA, fibronectin (FN), and Egr-1 were determined by real-time quantitative PCR and Western blotting, respectively. We observed that TGF-β1 significantly reduced E-cadherin expression and upregulated the expressions of FN, α-SMA, and Egr-1, which can be reversed by metformin. M61-Egr-1 transfection could exacerbate EMT, which can be reversed by metformin. Taken together, our data show that Egr-1 plays an important role in TGF-β1-induced EMT of renal tubular epithelial cells and metformin improves EMT while inhibiting Egr-1, which provides a potential novel target to combat renal fibrosis.

Metformin Regulating miR-34a Pathway to Inhibit Egr1 in Rat Mesangial Cells Cultured with High Glucose

BACKGROUND

Activating AMPKα negatively regulates Egr1 to inhibit inflammatory cytokines in high glucose. miR-34a inhibition increases phosphorylated AMPKα through mediating SIRT1 to suppress the development of fatty liver.

AIM OF THE STUDY

To clarify the function of Egr1 on the inflammation and fibrosis in high glucose-cultured MCs, as well as to explore the effects of metformin on miR-34a pathway and Egr1 expression.

METHODS

We transfected MCs with miR-34a inhibitor. And MCs were transfected with small interfering RNA for silencing Egr1 and SIRT1. Quantitative real-time PCR was used to assay the transcription levels of Egr1 mRNA and miR-34a. Western blot was used to test the protein. And ELISA was used to measure inflammatory factors.

RESULTS

High glucose upregulates Egr1 to aggravate the inflammation and fibrosis in MCs. miR-34a suppresses the activation of SIRT1/AMPKα and results in promoting Egr1 in high glucose-cultured MCs. Metformin attenuates high glucose-stimulated inflammation and fibrosis in MCs by regulating miR-34a-mediated SIRT1/AMPKα activity and the downstream Egr1 protein.

CONCLUSION

We enriched the effects of miR-34a pathway regulating Egr1 in high glucose-cultured MCs. It provides a foundation for future researches considering Egr1 as a therapeutic target and a new direction for the clinical application of metformin in early DKD.

Sustained hyperosmolarity increses TGF-ß1 and Egr-1 expression in the rat renal medulla

BACKGROUND

Although TGF-ß and the transcription factor Egr-1 play an important role in both kidney fibrosis and in response to acute changes of renal medullary osmolarity, their role under sustained hypo- or hyperosmolar conditions has not been elucidated. We investigated the effects of chronic hypertonicity and hypotonicity on the renal medullary TGF-ß and Egr-1 expression.

METHODS

Male adult Sprague Dawley rats (n = 6/group) were treated with 15 mg/day furosemide, or the rats were water restricted to 15 ml/200 g body weight per day. Control rats had free access to water and rodent chow. Kidneys were harvested after 5 days of treament. In cultured inner medullary collecting duct (IMCD) cells, osmolarity was increased from 330 mOsm to 900 mOsm over 6 days. Analyses were performed at 330, 600 and 900 mOsm.

RESULTS

Urine osmolarity has not changed due to furosemide treatment but increased 2-fold after water restriction (p < 0.05). Gene expression of TGF-ß and Egr-1 increased by 1.9-fold and 7-fold in the hypertonic medulla, respectively (p < 0.05), accompanied by 6-fold and 2-fold increased c-Fos and TIMP-1 expression, respectively (p < 0.05) and positive immunostaining for TGF-ß and Egr-1 (p < 0.05). Similarly, hyperosmolarity led to overexpression of TGF-ß and Egr-1 mRNA in IMCD cells (2.5-fold and 3.5-fold increase from 330 to 900 mOsm, respectively (p < 0.05)) accompanied by significant c-Fos and c-Jun overexpressions (p < 0.01), and increased Col3a1 and Col4a1 mRNA expression.

CONCLUSION

We conclude that both TGF-ß and Egr-1 are upregulated by sustained hyperosmolarity in the rat renal medulla, and it favors the expression of extracellular matrix components.

Klotho down-regulates Egr-1 by inhibiting TGF-β1/Smad3 signaling in high glucose treated human mesangial cells

Diabetic kidney disease (DKD) has become the leading cause of end-stage renal disease worldwide and is associated with glomerular mesangial cell (MC) proliferation and excessive extracellular matrix (ECM) production. Klotho can attenuate renal fibrosis in part by inhibiting TGF-β1/Smad3 signaling in DKD. Early growth response factor 1 (Egr-1) has been shown to play a key role in renal fibrosis in part by facilitating the formation of a positive feedback loop involving TGF-β1. However, whether Klotho down-regulates Egr-1 by inhibiting TGF-β1/Smad3 signaling in DKD is unclear. In the present study, we assessed human MCs that were incubated under high-glucose conditions to mimic diabetes. Then, we transfected the cells with Klotho plasmid or siRNA to overexpress or knock down Klotho gene and protein expression. Klotho, Egr-1, fibronectin (FN), collagen type I (Col I), Smad3 and phosphorylated Smad3 (p-Smad3) gene and protein expression levels were determined by RT-qPCR and western blotting respectively. High glucose time-dependently down-regulated Klotho mRNA and protein expression in cultured human MCs. pcDNA3.1-Klotho transfection-mediated Klotho overexpression down-regulated Egr-1, FN and Col I expression and the p-Smad3/Smad3 ratio in human MCs. Conversely, siRNA-mediated Klotho silencing up-regulated Egr-1, FN, and Col I expression and the p-Smad3/Smad3 ratio. Moreover, the effects of si-Klotho on Egr-1 expression were abolished by the TGF-β1 inhibitor SB-431542. Klotho overexpression can prevent mesangial ECM production in high-glucose-treated human MCs, an effect that has been partially attributed to Egr-1 down-regulation facilitated by TGF-β1/Smad3 signaling inhibition.

Glomeruli or interstitium targeted by inter-renal injections supplemented by electroporation: Still a useful tool in renal research

BACKGROUND

Studies concerning proteins are always a crucial part of renal research. As a result of current technologies, scientists have mastered several techniques for generating genetically modified animals. However, in most cases, accessing these animals is still time-consuming and often expensive. This makes the alteration of protein expression by in vivo plasmid transfection an easily-accessible alternative. However, there is still no comprehensive study describing where plasmids would be expressed when they are injected into the kidneys.

METHODS

We injected pEGFP-N1 into rats via intra-/inter-renal channels and detected green fluorescent protein (GFP) by immunohistochemistry and immunofluorescence to localize plasmid expression.

RESULTS

Seven days post-injection, we found that GFP was expressed in the glomeruli when pEGFP-N1 was injected via the renal artery or vein enhanced by electroporation and in the interstitium following injection via the ureter. Other channels, including intraperitoneal, subcapsule and parenchymal injection, only led to scattered expression within the kidneys.

CONCLUSIONS

The present study provides evidence that plasmid transfection via the renal vessels is suitable for glomeruli research and that transfection via the ureter is appropriate for studies regarding interstitium lesions. Additionally, we provide evidence that plasmid transfection on live animals is still an applicable and useful tool, as well as being cost-effective and facile.

Early growth response-1 in the pathogenesis of cardiovascular disease

This article reviews the regulatory roles of the immediate-early gene product and prototypic zinc finger transcription factor, early growth response-1 in models of cardiovascular pathobiology, focusing on insights using microRNA, DNAzymes, small hairpin RNA, small interfering RNA, oligonucleotide decoy strategies and mice deficient in early growth response-1.

Egr-1 mediates chronic hypoxia-induced renal interstitial fibrosis via the PKC/ERK pathway

BACKGROUND

Chronic hypoxia-induced epithelial-to-mesenchymal transition (EMT) is a crucial process in renal fibrogenesis. Egr-1, as a transcription factor, has been proven to be important in promoting EMT. However, whether it functions in hypoxia-induced renal tubular EMT has not been fully elucidated.

METHODS

Egr-1 were detected at mRNA and protein levels by qPCR and Western blot analysis respectively after renal epithelial cells were subjected to hypoxia treatment. Meanwhile, EMT phenotype was also observed through identification of relevant EMT-specific markers. siRNA was used to knock down Egr-1 expression and subsequent changes were observed. Specific PKC and MAPK/ERK inhibitors were employed to determine the molecular signaling pathway involved in Egr-1-mediated EMT phenotype. In vivo assays using rat remnant kidney model were used to validate the in vitro results. Furthermore, Egr-1 expression was examined in the samples of CKD patients with the clinical relevance revealed.

RESULTS

Hypoxia treatment enhanced the mRNA and protein levels of Egr-1 in HK-2 cells, which was accompanied by a reduced expression of the epithelial marker E-cadherin and an enhanced expression of the mesenchymal marker Fsp-1. Downregulation of Egr-1 with siRNA reversed hypoxia-induced EMT. Using the specific inhibitors to protein kinase C (calphostin C) or MAPK/ERK (PD98059), we identified that hypoxia induced Egr-1 expression through the PKC/ERK pathway. In addition, the upregulation of Egr-1 raised endogenous Snail levels, and the downregulation of Snail inhibited Egr-1-mediated EMT in HK-2 cells. Through in vivo assays using rat remnant kidney and CKD patients' kidney tissues, we found that Egr-1 and Snail were overexpressed in tubular epithelial cells with EMT.

CONCLUSION

Egr-1 may be an important regulator of the development of renal tubular EMT induced by hypoxia through the PKC/ERK pathway and the activation of Snail. Targeting Egr-1 expression or activity might be a novel therapeutic strategy to control renal fibrosis.

Molecular basis of organ fibrosis: potential therapeutic approaches

Fibrosis, a non-physiological wound healing in multiple organs, is associated with end-stage pathological symptoms of a wide variety of vascular injury and inflammation related diseases. In response to chemical, immunological and physical insults, the body's defense system and matrix synthetic machinery respond to healing the wound and maintain tissue homeostasis. However, uncontrolled wound healing leads to scarring or fibrosis, a pathological condition characterized by excessive synthesis and accumulation of extracellular matrix proteins, loss of tissue homeostasis and organ failure. Understanding the actual cause of pathological wound healing and identification of igniter(s) of fibrogenesis would be helpful to design novel therapeutic approaches to control pathological wound healing and to prevent fibrosis related morbidity and mortality. In this article, we review the significance of a few key cytokines (TGF-β, IFN-γ, IL-10) transcriptional activators (Sp1, Egr-1, Smad3), repressors (Smad7, Fli-1, PPAR-γ, p53, Klotho) and epigenetic modulators (acetyltransferase, methyltransferases, deacetylases, microRNAs) involved in major matrix protein collagen synthesis under pathological stage of wound healing, and the potentiality of these regulators as therapeutic targets for fibrosis treatment. The significance of endothelial to mesenchymal transition (EndMT) and senescence, two newly emerged fields in fibrosis research, has also been discussed.

Global gene expression profiling in PAI-1 knockout murine heart and kidney: molecular basis of cardiac-selective fibrosis

Fibrosis is defined as an abnormal matrix remodeling due to excessive synthesis and accumulation of extracellular matrix proteins in tissues during wound healing or in response to chemical, mechanical and immunological stresses. At present, there is no effective therapy for organ fibrosis. Previous studies demonstrated that aged plasminogen activator inhibitor-1 (PAI-1) knockout mice develop spontaneously cardiac-selective fibrosis without affecting any other organs. We hypothesized that differential expressions of profibrotic and antifibrotic genes in PAI-1 knockout hearts and unaffected organs lead to cardiac selective fibrosis. In order to address this prediction, we have used a genome-wide gene expression profiling of transcripts derived from aged PAI-1 knockout hearts and kidneys. The variations of global gene expression profiling were compared within four groups: wildtype heart vs. knockout heart; wildtype kidney vs. knockout kidney; knockout heart vs. knockout kidney and wildtype heart vs. wildtype kidney. Analysis of illumina-based microarray data revealed that several genes involved in different biological processes such as immune system processing, response to stress, cytokine signaling, cell proliferation, adhesion, migration, matrix organization and transcriptional regulation were affected in hearts and kidneys by the absence of PAI-1, a potent inhibitor of urokinase and tissue-type plasminogen activator. Importantly, the expressions of a number of genes, involved in profibrotic pathways including Ankrd1, Pi16, Egr1, Scx, Timp1, Timp2, Klf6, Loxl1 and Klotho, were deregulated in PAI-1 knockout hearts compared to wildtype hearts and PAI-1 knockout kidneys. While the levels of Ankrd1, Pi16 and Timp1 proteins were elevated during EndMT, the level of Timp4 protein was decreased. To our knowledge, this is the first comprehensive report on the influence of PAI-1 on global gene expression profiling in the heart and kidney and its implication in fibrogenesis and several other biological processes. The significance of these observations in the light of heart-specific profibrotic signaling and fibrogenesis are discussed.

Egr-1: new conductor for the tissue repair orchestra directs harmony (regeneration) or cacophony (fibrosis)

Fibroblasts and myofibroblasts are the key effector cells executing physiological tissue repair leading to regeneration on the one hand, and pathological fibrogenesis leading to chronic fibrosing conditions on the other. Recent studies identify the multifunctional transcription factor early growth response-1(Egr-1) as an important mediator of fibroblast activation triggered by diverse stimuli. Egr-1 has potent stimulatory effects on fibrotic gene expression, and aberrant Egr-1 expression or function is associated with animal models of fibrosis and human fibrotic disorders, including emphysema, pulmonary fibrosis, pulmonary hypertension and systemic sclerosis. Pharmacological suppression or genetic targeting of Egr-1 blocks fibrotic responses in vitro and ameliorates experimental fibrosis in the skin and lung. In contrast, Egr-1 appears to act as a negative regulator of hepatic fibrosis in mouse models, suggesting a context-dependent role in fibrosis. The Egr-1-binding protein Nab2 is an endogenous inhibitor of Egr-1-mediated signalling and abrogates the stimulation of fibrotic responses induced by transforming growth factor-β (TGFβ). Moreover, mice deficient in Nab2 show excessive collagen accumulation in the skin. These observations highlight a previously unsuspected fundamental physiological function for the Egr-1-Nab2 signalling axis in regulating fibrogenesis, and suggest that Egr-1 may be a potential novel therapeutic target in human diseases complicated by fibrosis. This review summarizes recent advances in understanding the regulation and complex functional role of Egr-1 and its related proteins and inhibitors in pathological fibrosis.

Enhancing effect of ultrasound-mediated microbubble destruction on gene delivery into rat kidney via different administration routes

OBJECTIVE

To investigate the efficiency of β-galactosidase gene transfer into rat kidney with ultrasound-mediated microbubble destruction via different injection routes.

METHODS

A total of 25 Wistar rats were randomly divided into 5 groups. Four groups received a mixture of optison microbubbles (0.2 mL) and lacz plasmids (25 μg) injection via renal artery, tail vein, anterior tibial muscle and renal parenchyma, respectively. The control group received a mixture of PBS (xx mL) and lacz plasmids (25 μg) via renal artery. Three days after the gene transfer, ultrasound with fixed frequency and power (1 MHz, xxW) was delivered to the kidneys for 3 min. The efficiency of the gene transfer and expression was evaluated on the basis of β-galactosidase expression. The side effects of this method were evaluated by immunohistological method.

RESULTS

β-galactosidase expression could be observed only in tubules but not in glomeruli and interstitial area. The efficiency of renal artery group was higher than that of tail vein, anterior tibial muscle and renal parenchyma group (P<0.05). Immunohistochemical analysis revealed co-expression of β-galactosidase with a roximal tubule marker, megalin, which suggested that ultrasound enhanced gene transfer into the proximal tubular epithelial cells. No β-galactosidase expression was observed in the extrarenal organs. There were no evident pathological and biochemical changes after gene transfer.

CONCLUSIONS

Ultrasound-mediated microbubble destruction can transfer gene into kidney via renal artery, tail vein, anterior tibial muscle and renal parenchyma. Compared with renal artery, administrating microbubbles via tail vein and anterior tibial muscle are more convenient and less vulnerarious.

Cyclic nucleotide phosphodiesterase 1A: a key regulator of cardiac fibroblast activation and extracellular matrix remodeling in the heart

Cardiac fibroblasts become activated and differentiate to smooth muscle-like myofibroblasts in response to hypertension and myocardial infarction (MI), resulting in extracellular matrix (ECM) remodeling, scar formation and impaired cardiac function. cAMP and cGMP-dependent signaling have been implicated in cardiac fibroblast activation and ECM synthesis. Dysregulation of cyclic nucleotide phosphodiesterase (PDE) activity/expression is also associated with various diseases and several PDE inhibitors are currently available or in development for treating these pathological conditions. The objective of this study is to define and characterize the specific PDE isoform that is altered during cardiac fibroblast activation and functionally important for regulating myofibroblast activation and ECM synthesis. We have found that Ca(2+)/calmodulin-stimulated PDE1A isoform is specifically induced in activated cardiac myofibroblasts stimulated by Ang II and TGF-β in vitro as well as in vivo within fibrotic regions of mouse, rat, and human diseased hearts. Inhibition of PDE1A function via PDE1-selective inhibitor or PDE1A shRNA significantly reduced Ang II or TGF-β-induced myofibroblast activation, ECM synthesis, and pro-fibrotic gene expression in rat cardiac fibroblasts. Moreover, the PDE1 inhibitor attenuated isoproterenol-induced interstitial fibrosis in mice. Mechanistic studies revealed that PDE1A modulates unique pools of cAMP and cGMP, predominantly in perinuclear and nuclear regions of cardiac fibroblasts. Further, both cAMP-Epac-Rap1 and cGMP-PKG signaling was involved in PDE1A-mediated regulation of collagen synthesis. These results suggest that induction of PDE1A plays a critical role in cardiac fibroblast activation and cardiac fibrosis, and targeting PDE1A may lead to regression of the adverse cardiac remodeling associated with various cardiac diseases.

Deoxyribozymes: new therapeutics to treat central nervous system disorders

This mini-review focuses on a knockdown technology called deoxyribozymes, which has rarely been utilized in the field of neurobiology/neuroscience. Deoxyribozymes are catalytic DNA molecules, which are also entitled DNA enzyme or DNAzyme. This mini-review presents a description of their development, structure, function, and therapeutic application. In addition, information on siRNA, ribozymes, and antisense are given. Further information on two deoxyribozymes against c-Jun and xylosyltransferase (XT) mRNA are summarized of which the first is important to influence many neurological disorders and the last potentially treats spinal cord injuries (SCIs). In particular, insults to the central nervous system (CNS) such as SCI generate an inhibitory environment (lesion scar) at the injury site that prevents the endogenous and therapy-induced axonal regeneration and thereby limits repair strategies. Presently, there are no treatments available. Hence, deoxyribozymes provide an opportunity for new therapeutics that alter the inhibitory nature of the lesion scar and thus promote axonal growth in the injured spinal cord. When used cautiously and within the limits of its ability the deoxyribozyme technology holds promise to become a major contributing factor in repair strategies of the CNS.

Diurnal regulation of the early growth response 1 (Egr-1) protein expression by hepatocyte nuclear factor 4alpha (HNF4alpha) and small heterodimer partner (SHP) cross-talk in liver fibrosis

Early growth response 1 (Egr-1) protein is a critical regulator of genes contributing to liver fibrosis; however, little is known about the upstream transcriptional factors that control its expression. Here we show that Egr-1 expression is tightly regulated by nuclear receptor signaling. Hepatocyte nuclear factor 4α (HNF4α) activated the Egr-1 promoter through three DR1 response elements as identified by trans-activation assays. Deletion of these response elements or knockdown of HNF4α using siRNA largely abrogated Egr-1 promoter activation. HNF4α activity, as well as its enrichment on the Egr-1 promoter, were markedly repressed by small heterodimer partner (SHP) co-expression. Egr-1 mRNA and protein were transiently induced by HNF4α. On the contrary, HNF4α siRNA reduced Egr-1 expression at both the mRNA and protein levels, and overexpression of SHP reversed these effects. Conversely, knockdown of SHP by siRNA elevated Egr-1 protein. Interestingly, Egr-1 mRNA exhibited diurnal fluctuation, which was synchronized to the cyclic expression of SHP and HNF4α after cells were released from serum shock. Unexpectedly, the levels of Egr-1 mRNA and protein were highly up-regulated in Hnf4α(-/-) mice. Both HNF4α and Egr-1 expression were dramatically increased in SHP(-/-) mice with bile duct ligation and in human cirrhotic livers, which was inversely correlated with diminished SHP expression. In conclusion, our study revealed control network for Egr-1 expression through a feedback loop between SHP and HNF4α.

A molecular signature of proteinuria in glomerulonephritis

Proteinuria is the most important predictor of outcome in glomerulonephritis and experimental data suggest that the tubular cell response to proteinuria is an important determinant of progressive fibrosis in the kidney. However, it is unclear whether proteinuria is a marker of disease severity or has a direct effect on tubular cells in the kidneys of patients with glomerulonephritis. Accordingly we studied an in vitro model of proteinuria, and identified 231 “albumin-regulated genes” differentially expressed by primary human kidney tubular epithelial cells exposed to albumin. We translated these findings to human disease by studying mRNA levels of these genes in the tubulo-interstitial compartment of kidney biopsies from patients with IgA nephropathy using microarrays. Biopsies from patients with IgAN (n = 25) could be distinguished from those of control subjects (n = 6) based solely upon the expression of these 231 “albumin-regulated genes.” The expression of an 11-transcript subset related to the degree of proteinuria, and this 11-mRNA subset was also sufficient to distinguish biopsies of subjects with IgAN from control biopsies. We tested if these findings could be extrapolated to other proteinuric diseases beyond IgAN and found that all forms of primary glomerulonephritis (n = 33) can be distinguished from controls (n = 21) based solely on the expression levels of these 11 genes derived from our in vitro proteinuria model. Pathway analysis suggests common regulatory elements shared by these 11 transcripts. In conclusion, we have identified an albumin-regulated 11-gene signature shared between all forms of primary glomerulonephritis. Our findings support the hypothesis that albuminuria may directly promote injury in the tubulo-interstitial compartment of the kidney in patients with glomerulonephritis.

Hepatic fibrosis is enhanced and accompanied by robust oval cell activation after chronic carbon tetrachloride administration to Egr-1-deficient mice

The transcription factor early growth response (Egr)-1 regulates the expression of genes required for execution of the wound healing response. Multiple cycles of injury, coupled to incomplete wound healing, lead to fibrosis. Therefore, we hypothesized that Egr-1 is required for the development of hepatic fibrosis. To test this hypothesis, we exposed wild-type and egr-1(-/-) mice to acute or chronic carbon tetrachloride (CCl(4)). Acute CCl(4) exposure established a profibrotic milieu in the liver, including activation of hepatic stellate cells as well as expression of type 1 collagen genes and tissue inhibitor of matrix metalloproteinase 1 in both wild-type and egr-1(-/-) mice. This response was exacerbated in egr-1(-/-) mice. After chronic CCl(4) exposure, hepatic fibrosis was established in both genotypes; however, the fibrotic response was profoundly worsened in Egr-1-deficient mice. Importantly, enhanced fibrosis in egr-1(-/-) mice was accompanied by a robust activation of the oval cell response, suggesting more severe liver injury and/or reduced hepatocyte proliferation when compared with wild-type mice. Hepatic expression of genes indicative of oval cell activation, as well as the number of cells expressing A6, a mouse oval cell marker, was greater in egr-1(-/-) mice. Taken together, these data reveal novel roles for Egr-1 as a negative regulator of both CCl(4)-induced hepatic fibrosis and the oval cell response.

[Development of nucleic acid transfection technology to the kidney]

The kidney is one of the most important organs that play a crucial role in homeostasis and, therefore, congenital or acquired renal dysfunction causes refractory diseases, i.e., Alport's syndrome, Fabry's disease, diabetic nephropathy, IgA nephropathy, kidney cancer, transplant glomerulopathy. Nucleic acid transfection technology to the kidney is indispensable for the progress of biomedical research and the realization of gene therapy and nucleic acid drug for renal diseases. Control of renal nucleic acid transfection was difficult because of the structural complexity; however, the study of recombinant virus, synthetic carrier and physical force-mediated nucleic acid transfection to the kidney has advanced. Recombinant virus and synthetic carrier-mediated methods require long-term block of the blood or urinary flow for efficient transfection of nucleic acid because of the rich blood flow of the kidney. In contrast, physical force-mediated methods that transfect with nucleic acid via transient membrane permeability do not apprehend ischemia-reperfusion injury and, therefore, may be beneficial for nucleic acid transfection to the kidney. In this article, we collect the information of therapeutic gene, target molecule of the nucleic acid drug and target cells for renal diseases and structural property of the kidney from the point of view of nucleic acid transfection. Additively, current status of nucleic acid transfection technology to the kidney is reviewed.

Brothers in arms: DNA enzymes, short interfering RNA, and the emerging wave of small-molecule nucleic acid-based gene-silencing strategies

The past decade has seen the rapid evolution of small-molecule gene-silencing strategies, driven largely by enhanced understanding of gene function in the pathogenesis of disease. Over this time, many genes have been targeted by specifically engineered agents from different classes of nucleic acid-based drugs in experimental models of disease to probe, dissect, and characterize further the complex processes that underpin molecular signaling. Arising from this, a number of molecules have been examined in the setting of clinical trials, and several have recently made the successful transition from the bench to the clinic, heralding an exciting era of gene-specific treatments. This is particularly important because clear inadequacies in present therapies account for significant morbidity, mortality, and cost. The broad umbrella of gene-silencing therapeutics encompasses a range of agents that include DNA enzymes, short interfering RNA, antisense oligonucleotides, decoys, ribozymes, and aptamers. This review tracks current movements in these technologies, focusing mainly on DNA enzymes and short interfering RNA, because these are poised to play an integral role in antigene therapies in the future.

Electroporation-mediated gene therapy

Non-viral gene transfer is markedly enhanced by the application of in vivo electroporation. Electroporation is a safe and efficient system to introduce genes to a wide variety of tissues, including skeletal muscle, tumors, kidney, liver and skin. Electroporation has been demonstrated to be effective in numerous disease models. This review focuses on the principles of electroporation and the target tissues employed for gene therapy. Based on the accumulation of positive results, the first clinical study for the treatment of malignant melanoma is now underway, and preclinical studies have suggested that electroporation is useful as a gene therapy protocol.

Gene therapy targeting kidney diseases: routes and vehicles

Renal gene therapy may offer new strategies to treat diseases of native and transplanted kidneys. Several experimental techniques have been developed and employed using nonviral, viral, and cellular vectors. The most efficient viral vector for in vivo transfection appears to be adenovirus. In addition, enhanced naked plasmid techniques, such as the hemagglutinating virus of Japan (HVJ)-liposome method, electroporation, the hydrodynamic method, and ultrasound with microbubbles, are promising. Trapping genetically modified macrophages in the inflamed kidneys is an elegant method for site-specific gene delivery. The choice of delivery vehicle as well as the administration route determines the site of transduction. In conclusion, for both in vivo and ex vivo renal transfection, enhanced naked plasmids, adenoviruses, and modified cell vectors offer the best prospects for effective clinical application. Moreover, the development of safer and nonimmunogenic vectors may realize clinical renal gene therapy in the near future.

The transcription factor Egr1 is a direct regulator of multiple tumor suppressors including TGFbeta1, PTEN, p53, and fibronectin

Recent studies are reviewed indicating that the transcription factor early growth response-1 (Egr1) is a direct regulator of multiple tumor suppressors including TGFbeta1, PTEN, p53, and fibronectin. The downstream pathways of these factors display multiple nodes of interaction with each other, suggesting the existence of a functional network of suppressor factors that serve to maintain normal growth regulation and resist the emergence of transformed variants. Paradoxically, Egr1 is oncogenic in prostate cancer. In the majority of these cancers, PTEN or p53 is inactive. It is suggested that these defects in the suppressor network allow for the unopposed induction of TGFbeta1 and fibronectin, which favor transformation and survival of prostate tumor epithelial cells, and explain the role of Egr1 in prostate cancer. Egr1 is a novel and logical target for intervention by gene therapy methods, and targeting methods are discussed.

Obstructive nephropathy: towards biomarker discovery and gene therapy

Obstructive nephropathy is a major cause of renal failure, particularly in infants and children. Cellular and molecular mechanisms responsible for the progression of the tubular atrophy and interstitial fibrosis-processes that lead to nephron loss-have been elucidated in the past 5 years. Following urinary tract obstruction and tubular dilatation, a cascade of events results in upregulation of the intrarenal renin-angiotensin system, tubular apoptosis and macrophage infiltration of the interstitium. This is followed by accumulation of interstitial fibroblasts through proliferation of resident fibroblasts and epithelial-mesenchymal transformation of renal tubular cells. Under the influence of cytokines, chemokines and other signaling molecules produced by tubular and interstitial cells, fibroblasts undergo transformation to myofibroblasts that induce expansion of the extracellular matrix. The cellular interactions that regulate development of interstitial inflammation, tubular apoptosis and interstitial fibrosis are complex. Changes in renal gene expression and protein production afford many potential biomarkers of disease progression and targets for therapeutic manipulation. These include signaling molecules and receptors involved in macrophage recruitment and proliferation, tubular death signals and survival factors, and modulators of epithelial-mesenchymal transformation. Targeted gene deletion and various forms of gene therapy have been used in experimental obstructive nephropathy, mostly rodent models of unilateral ureteral obstruction or cell culture techniques. Further refinement of these models is needed to develop a matrix of biomarkers with clinical predictive value, as well as molecular therapies that will prevent or reverse the renal structural and functional consequences of obstructive nephropathy.

Targeting of interstitial cells using a simple gene-transfer strategy

BACKGROUND

Interstitial fibroblasts are central to the inflammatory response during the progression of tubulointerstitial fibrosis. We examined the efficiency of a new gene transfer method that targets interstitial cells by using parenchymal injection of DNA followed by electroporation.

METHODS

Fluoresceinisothiocyanate-labelled oligodeoxynucleotides (FITC-ODNs) or expression vectors were directly injected into the cortex of the kidney, followed by electroporation.

RESULTS

Transfection with FITC-ODNs or the EGFP expression vector resulted in efficient transfection in interstitial fibroblasts, but not in tubular epithelial cells or glomerular cells. Transfection efficiency was optimal after using a total of 150 microg of DNA in 1000 microl of PBS, combined with clamping of the renal vessels prior to electroporation. Gene expression peaked at 4 days after transfection and decreased by two orders of magnitude at 6 weeks post-transfection; however, expression recovered to near peak levels after parenchymal or intraperitoneal injection of FR901228, a histone deacetylase inhibitor.

CONCLUSION

We demonstrated that direct parenchymal injection of DNA combined with electroporation enables gene transfer into interstitial fibroblasts.

Transcription factor Ets-1 is essential for mesangial matrix remodeling

Most advanced glomerular diseases are characterized by abnormal extracellular matrix (ECM) accumulation in the glomeruli, and matrix metalloproteinases (MMPs) play a pivotal role in ECM remodeling in various glomerular diseases. The proto-oncogene, ets-1, is a transcription factor regulating the expression of various matrix proteinases, including MMP-1, MMP-3, and MMP-9. The goal of the present study was to characterize the role of Ets-1 in the progression of glomerular diseases. Overexpression of Ets-1 in cultured mesangial cells prevented transforming growth factor (TGF)-beta-induced inhibition of DNA-binding activity and TGF-beta-induced type I collagen production. In addition, exogenous Ets-1 abolished TGF-beta-induced collagen gel contraction. The in vivo transfection of the ets-1 gene into nephritic kidney resulted in the increases in glomerular MMP-1, MMP-3, and MMP-9 mRNA, decreases in mesangial ECM deposition, and attenuation of fibronectin extradomain A (EDA) and type I collagen expression. In contrast, knockdown of Ets-1 in glomeruli resulted in severe ECM deposition in diseased glomeruli. In conclusion, Ets-1 promotes degradation of ECM proteins and is critical for integral glomerular reorganization.

The early-immediate gene EGR-1 is induced by transforming growth factor-beta and mediates stimulation of collagen gene expression

Transforming growth factor-beta (TGF-beta) stimulates collagen synthesis and accumulation, and aberrant TGF-beta signaling is implicated in pathological organ fibrosis. Regulation of type I procollagen gene (COL1A2) transcription by TGF-beta involves the canonical Smad signaling pathway as well as additional protein and lipid kinases, coactivators, and DNA-binding transcription factors that constitute alternate non-Smad pathways. By using Affymetrix microarrays to detect cellular genes whose expression is regulated by Smad3, we identified early growth response factor-1 (EGR-1) as a novel Smad3-inducible gene. Previous studies implicated Egr-1 in cell growth, differentiation, and survival. We found that TGF-beta induced rapid and transient accumulation of Egr-1 protein and mRNA in human skin fibroblasts. In transient transfection assays, TGF-beta stimulated the activity of the Egr-1 gene promoter, as well as that of a minimal Egr-1-responsive reporter construct. Furthermore, TGF-beta enhanced endogenous Egr-1 interaction with a consensus Egr-1-binding site element and with GC-rich DNA sequences of the human COL1A2 promoter in vitro and in vivo. Forced expression of Egr-1 by itself caused dose-dependent up-regulation of COL1A2 promoter activity and further enhanced the stimulation induced by TGF-beta. In contrast, the TGF-beta response was abrogated when the Egr-1-binding sites of the COL1A2 promoter were mutated or deleted. Furthermore, Egr-1-deficient embryonic mouse fibroblasts showed attenuated TGF-beta responses despite intact Smad activation, and forced expression of ectopic EGR-1 in these cells could restore COL1A2 stimulation in a dose-dependent manner. Taken together, these findings identify Egr-1 as a novel intracellular TGF-beta target that is necessary for maximal stimulation of collagen gene expression in fibroblasts. The results therefore implicate Egr-1 in the profibrotic responses elicited by TGF-beta and suggest that Egr-1 may play a new and important role in the pathogenesis of fibrosis.

Early growth response-1 in cardiovascular pathobiology

The immediate-early gene product and zinc finger transcription factor early growth response (Egr)-1 plays a key master regulatory role in multiple cardiovascular pathological processes. This article reviews the amazing recent evidence implicating Egr-1 in atherosclerosis, intimal thickening after acute vascular injury, ischemic pathology, angiogenesis, allograft rejection, and cardiac hypertrophy.

Enhanced transduction of fibroblasts in transplanted kidney with an adenovirus having an RGD motif in the HI loop

Application of gene therapy to the renal graft has a powerful potential to improve the outcome of kidney transplantation and eliminate detrimental side effects associated with systemic therapy, through local expression of immunoregulatory or other protective molecules. However, the search for the optimal vector is still ongoing. In this study, we used a modified adenovirus that has an Arg-Gly-Asp (RGD) motif inserted in the HI loop of the fiber knob, as a successful strategy to transduce the renal graft. Donor Lewis rat kidneys were infused via the renal artery with a solution containing either a fiber-modified adenovirus (AdTL-RGD) or an unmodified adenovirus (AdTL), or with saline. Syngeneic recipients were killed after 3, 7 or 14 days. Efficiency, selectivity, localization, time course of gene expression and side effects were studied using biochemical and immunohistological techniques. Enhanced gene expression was achieved selectively in the transplanted kidney by AdTL-RGD, when compared to AdTL. Transgene expression lasted for at least 2 weeks. With the AdTL-RGD vector, the transgene was abundantly expressed in the renal interstitial fibroblasts. An increase in the number of cytotoxic T lymphocytes accompanied the use of either vector, when compared to saline. These data convincingly show enhanced and selective gene transfer to the fibroblasts of transplanted kidneys using an RGD-modified adenovirus, providing a highly efficient vector system for future therapeutic interventions.

FVIII gene delivery by muscle electroporation corrects murine hemophilia A

BACKGROUND

Hemophilia A treatment relies on costly factor VIII (FVIII) replacement that may transmit iatrogenic viral diseases. Viral vectors and cell implants are being developed as improvements. We investigated in vivo electroporation of naked DNA as a safe and simple method for correcting FVIII deficiency.

METHODS

B-domain-deleted murine FVIII cDNA expression plasmids were constructed with CMV and elongation factor 1alpha promoters for characterisation in murine C2C12 myoblasts. The construct conferring highest in vitro FVIII secretion was electroporated into skeletal muscle of FVII null mice in vivo for phenotypic correction using a protocol that minimised tissue injury.

RESULTS

B-domain-deleted murine FVIII cDNA plasmids induced FVIII secretion from stably transfected C2C12 myoblasts (0.54+/-0.20 mU/day/10(5) cells). Phenotypic correction of hemophilic mice was more consistently achieved using a protocol for in vivo electroporation of gastrocnemius muscle with FVIII cDNA that reduced tissue injury by the use of plate electrodes, hyaluronidase pre-treatment and lower field strength. This technique was associated with <10% muscle necrosis. Activated partial thromboplastin time decreased from 51.4+/-3.3 to 34.7+/-1.1 (mean+/-s.e.m.) seconds (p=0.0004) following in vivo electroporation (0.1 mg plasmid/limb; 8x20 ms pulses, 175 V/cm, 1 Hz) of hemophilic mice. All hemophilic mice (8/8) survived hemostatic challenge after muscle electroporation with FVIII cDNA, whereas all (9/9) untreated hemophilic mice died. Plasmid DNA was detectable only in electroporated muscle and not in all other organs tested, including gonads.

CONCLUSION

In vivo intramuscular electroporation of naked FVIII plasmid successfully corrects murine hemophilia.

Exploring RNA interference as a therapeutic strategy for renal disease

The short synthetic interfering RNA duplexes (siRNAs) can selectively suppress gene expression in somatic mammalian cells without nonselective toxic effects of double-stranded RNA (dsRNA). However, a selective in vivo delivery of siRNA transfer has not been reported in kidney. Here, we investigated whether injection of synthetic siRNAs via renal artery followed by electroporation could be effective and therapeutic in silencing specific gene in glomerulus. We investigated the effect of siRNA in rat cultured mesangial cells (MCs) and showed that siRNA sequence-specific suppression of transgene expression was over a 1000-fold more potent than that by antisense oligodeoxynucleotide (ASODN). Transfection of siRNA targeting luciferase into rat kidneys significantly inhibited expression of a cotransfected luciferase expression vector in vivo. The delivery of siRNA targeting enhanced green fluorescent protein (EGFP) in the transgenic 'green' rat reduced endogenous EGFP expression, mainly in glomerular MCs. Furthermore, RNAi targeting against TGF-beta1 significantly suppressed TGF-beta1 mRNA and protein expression, thereby ameliorated the progression of matrix expansion in experimental glomerulonephritis. In addition, vector-based RNAi also inhibited TGF-beta1 expression in vitro and in vivo. In conclusion, siRNA-directed TGF-beta1 silencing may be of therapeutic value in the prevention and treatment of fibrotic diseases.

Gene therapy for renal disorders

During the last 20 years there have been major improvements in renal replacement therapy, including dialysis and kidney transplantation; however, the treatment options for renal diseases are still limited. Gene therapy is a potential modality for many renal diseases for which we are as yet unable to offer specific treatment. This article reviews the recent data on gene therapy in animal models applicable to human renal diseases and evaluates its efficacy, safety and clinical relevance. Several approaches appear to be promising, including adeno-associated viral vectors for long-term gene expression, electroporation for muscular gene delivery, ultrasound/microbubble-mediated gene targeting, macrophage-based gene therapy and small interfering RNAs.

Electroporation-mediated HGF gene transfer ameliorated cyclosporine nephrotoxicity

BACKGROUND

The clinical utility of cyclosporine A (CsA) has been limited by its nephrotoxicity, which is characterized by tubular atrophy, interstitial fibrosis, and progressive renal impairment. Hepatocyte growth factor (HGF) has been reported to protect and salvage from renal injury as a renotropic and antifibrotic factor. Here, we investigated protective effects of HGF gene therapy on rat CsA-induced nephrotoxicity using electroporation-mediated gene transfer.

METHOD

CsA was subcutaneously administered daily under low sodium diet, and HGF gene was transferred into skeletal muscle by electroporation on days 7 and 14. We also examined the antiapoptotic mechanism of HGF using human proximal tubular epithelial cells.

RESULTS

HGF gene transfer rescued CsA-induced initial tubular injury and suppressed interstitial infiltration of ED-1-positive macrophages in CsA-induced nephrotoxicity. In addition, HGF significantly inhibited tubular cell apoptosis, and increased the number of proliferating tubular epithelial cells. In vitro studies suggest that HGF executes the antiapoptotic function by enhancing the phosphorylation of Akt and Bcl-2. Northern blot analysis demonstrated that HGF gene transfer suppressed cortical mRNA levels of transforming growth factor-beta (TGF-beta). Consequently, HGF gene transfer significantly reduced a striped interstitial phenotypic alteration and fibrosis.

CONCLUSION

We demonstrated that HGF gene transfer reduced CsA-induced tubular cell apoptosis and interstitial fibrosis. HGF gene transfer could be a potential strategy for preventing renal fibrosis.

Approaches and methods in gene therapy for kidney disease

Renal gene therapy may offer new strategies to treat diseases of native and transplanted kidneys. Several experimental techniques have been developed and employed using nonviral, viral, and cellular vectors. The most efficient vector for in vivo transfection appears to be adenovirus. Glomeruli, blood vessels, interstitial cells, and pyelum can be transfected with high efficiency. In addition, electroporation and microbubbles with ultrasound, both being enhanced naked plasmid techniques, offer good opportunities. Trapping of mesangial cells into the glomeruli as well as natural targeting of monocytes or macrophages to inflamed kidneys are elegant methods for site-specific delivery of genes. For gene therapy in kidney transplantation, hemagglutinating virus of Japan liposomes are efficient vectors for tubular transfection, whereas enhanced naked plasmid techniques are suitable for glomerular transfection. However, adenovirus offers the best opportunities in a renal transplantation setup because varying parameters of graft perfusion allows targeting of different cell types. In renal grafts, lymphocytes can be used for selective targeting to sites of inflammation. In conclusion, for both in vivo and ex vivo renal transfection, enhanced naked plasmids and adenovirus offer the best perspectives for effective clinical application. Moreover, the development of safer, nonimmunogenic vectors and the large-scale production could make clinical renal gene therapy a realistic possibility for the near future.

Gene therapy in renal diseases

Kidney-targeted gene therapy could be an ideal treatment for renal diseases since the therapeutic molecule is limited in the kidney and the systemic effect may be minimized. The technical development of the gene delivery to kidney and the identification of the responsive gene for a particular disease encourage the challenge to hereditary diseases. Collagen type IV reassembling was reported to be succeeded in Alport syndrome model by introduction of exogenous COL4A5 gene. Many gene therapies are evaluated in various glomerulonephritis models and unilateral ureteral obstruction (UUO) model, and favorable results are accumulated. Transplant kidney is an ideal target for gene therapy, by which ischemia reperfusion, acute rejection and chronic allograft nephropathy can be treated. The importation of the novel technology, for example hybrid stem cell-gene therapy could promote the gene therapy of renal diseases toward clinical application.

Perspectives for gene therapy in renal diseases

Somatic cell gene therapy has made considerable progress last five years and has shown clear success in some clinical trials. In the field of nephrology, both the elucidation of pathophysiology of renal diseases and the development of gene transfer technique have become driving force for new therapy of incurable renal diseases, such as Alport syndrome and polycystic kidney disease. Gene therapy of renal cancer, although its application is limited to advanced cancer, is the front-runner of clinical application. Erythropoietin gene therapy has provided encouraging results for the treatment of anemia in uremic rats and recently progressed to the inducible one in response to hypoxia. Gene therapy for glomerulonephritis and renal fibrosis showed prominent impact on experimental models, although the safety must be confirmed for prolonged treatment. Transplant kidney is an ideal material for gene modification and induction of tolerance in the transplant kidney is an attractive challenge. Emerging techniques are becoming available such as stem cell technology and messenger RNA silencing strategies. We believe that the future of gene therapy research is exciting and promising and it holds an enormous potential for clinical application.

Electroporation-mediated delivery of catalytic oligodeoxynucleotides for manipulation of vascular gene expression

The development of inexpensive and effective approaches to transiently decrease gene expression in vivo would be useful for the study of physiological processes in living animals. DNAzymes are a novel class of DNA oligonucleotides that can catalytically cleave target mRNAs and thereby reduce protein production. However, current methods for their delivery in vivo are limited and inefficient. In this study, we show that electroporation can be used to deliver DNAzymes to the intact mesenteric vasculature of rats. With the use of PKC-epsilon as a target, a set of wild-type and mutant control DNAzymes was designed and shown to reduce both PKC-epsilon mRNA and protein levels in cultured smooth muscle cells in a specific manner. The wild-type DNAzyme reduced PKC-epsilon protein levels by 70% at 24 h in two different cell lines without decreasing the levels of the five other PKC isoforms tested. When delivered to the intact vasculature using electroporation, the DNAzyme reduced PKC-epsilon protein levels by >60% without affecting these other PKC isoforms. Electroporation was required for oligonucleotide transfer and was able to deliver the DNAzymes to multiple cell layers in the vessel wall. Protein levels were reduced maximally by 24 h postelectroporation and returned to normal by 48 h. These results suggest that electroporation can be used to deliver DNAzymes and other DNA oligonucleotides to the vasculature in vivo and can decrease gene expression for a window of time that can be used for experimental studies.

Anti-monocyte chemoattractant protein-1 gene therapy attenuates renal injury induced by protein-overload proteinuria

It has been postulated that protein filtered through glomeruli activates tubular epithelial cells, which secrete vasoactive and inflammatory substances including chemokines, leading to tubulointerstitial renal injury. The present study was designed to investigate the role of monocyte chemoattractant protein-1 (MCP-1) in this process and to evaluate the effectiveness of a kidney-targeted gene transfer technique using hydrodynamic pressure. Naked plasmid encoding 7ND (an MCP-1 antagonist) or a control plasmid was introduced into the left kidney of rats. Three days after gene transfer (day 0), intraperitoneal administration of bovine serum albumin (10 mg/g body wt per day) was started and continued for 14 or 21 d. RT-PCR showed that 7ND mRNA was expressed only in the gene-transfected kidney. Immunostaining showed that 7ND protein was localized in the interstitial cells. Macrophage infiltration was significantly reduced in the left kidney of rats treated with 7ND on days 14 and 21. In the right kidney, such effects were not observed. 7ND also attenuated tubular damage and decreased the number of apoptotic cells. Computer-assisted analysis revealed that the areas positively stained for alpha-smooth muscle actin (alpha SMA), fibronectin-EDA, type I collagen, and collagen fibrils were significantly reduced in the 7ND-treated kidney on day 21. Furthermore, 7ND gene therapy significantly reduced MCP-1 and TGF-beta 1 mRNA expression. These results demonstrate that MCP-1 plays an important role in the development of tubulointerstitial inflammation, tubular damage, and fibrosis induced by proteinuria. The fact that 7ND gene therapy had little effect on the contralateral kidney indicates that 7ND acted locally. This strategy may have a potential usefulness as a gene therapy against tubulointerstitial renal injury.

TGF-beta signal transduction and mesangial cell fibrogenesis

Transforming growth factor-beta (TGF-beta) is closely associated with progressive renal fibrosis. Significant progress has been accomplished in determining the cellular signaling pathways that are activated by TGF-beta. This knowledge is being applied to glomerular mesangial cell models of extracellular matrix (ECM) accumulation. A central component of TGF-beta-stimulated mesangial cell fibrogenesis is the TGF-beta family-specific Smad signal transduction pathway. However, while Smads play an important role in collagen accumulation, recent findings indicate that cross talk among a variety of pathways is necessary for maximal stimulation of collagen expression. Further investigation of these multiple interactions will provide insight into possible ways to interrupt cellular mechanisms of glomerular fibrogenesis.

Transcription factor Egr-1 activates collagen expression in immortalized fibroblasts or fibrosarcoma cells

Synovial fibroblasts from rheumatoid arthritis patients express elevated levels of the transcription factor Egr-1. The metabolic consequences of Egr-1 overexpression in fibroblasts are not known in detail. Therefore we searched for gene products that are differentially expressed in Egr-1(high) versus Egr-1(low) fibroblasts. Immortalized synovial fibroblasts were transfected with two different Egr-1 expression vectors. Expression of recombinant Egr-1 was confirmed by RT-PCR and immunoblots. Random arbitrarily primed PCR revealed that Egr-1 induces enhanced transcription levels of the alpha1 chain of type I collagen. Increased expression of the alpha2 (I) chain could also be observed. We found enhanced levels of type I collagen propeptide in supernatants and stronger signals of alpha2 (I) protein in extracts of the Egr-1(high) expressing clone versus controls. Additionally, Egr-1 was transiently expressed in fibrosarcoma cells. These cells showed a pronounced elevation of type I collagen (alpha1) transcripts as well. Moreover, we could demonstrate that Egr-1 induces transcription of other genes including type II collagen (alpha1) and plateled-derived growth factor beta1. These data suggest that upregulation of Egr-1 might contribute tofibrosis observed in rheumatoid arthritis synovium by activation of genes encoding the alpha1 and alpha2 chains of type I collagen.