The Basic Helix‐Loop‐Helix/Leucine Zipper Transcription Factor USF2 Integrates Serum‐Induced PAI‐1 Expression and Keratinocyte Growth

Tang

et al. 2018

Cellular Signalling

Self Cite

130

Fibrotic disorders of the renal, pulmonary, cardiac, and hepatic systems are associated with significant morbidity and mortality. Effective therapies to prevent or curtail the advancement to organ failure, however, remain a major clinical challenge. Chronic kidney disease, in particular, constitutes an increasing medical burden affecting >15% of the US population. Regardless of etiology (diabetes, hypertension, ischemia, acute injury, urologic obstruction), persistently elevated TGF-β1 levels are causatively linked to the activation of profibrotic signaling networks and disease progression. TGF-β1 is the principal driver of renal fibrogenesis, a dynamic pathophysiologic process that involves tubular cell injury/apoptosis, infiltration of inflammatory cells, interstitial fibroblast activation and excess extracellular matrix synthesis/deposition leading to impaired kidney function and, eventually, to chronic and end-stage disease. TGF-β1 activates the ALK5 type I receptor (which phosphorylates SMAD2/3) as well as non-canonical (e.g., src kinase, EGFR, JAK/STAT, p53) pathways that collectively drive the fibrotic genomic program. Such multiplexed signal integration has pathophysiological consequences. Indeed, TGF-β1 stimulates the activation and assembly of p53-SMAD3 complexes required for transcription of the renal fibrotic genes plasminogen activator inhibitor-1, connective tissue growth factor and TGF-β1. Tubular-specific ablation of p53 in mice or pifithrin-α-mediated inactivation of p53 prevents epithelial G/M arrest, reduces the secretion of fibrotic effectors and attenuates the transition from acute to chronic renal injury, further supporting the involvement of p53 in disease progression. This review focuses on the pathophysiology of TGF-β1-initiated renal fibrogenesis and the role of p53 as a regulator of profibrotic gene expression.

Section: Integration Of Tgf-β1-activated P53 In Renal Fibrogenesismentioning

confidence: 96%

TGF-β1/p53 signaling in renal fibrogenesis

Tang

et al. 2018

Cellular Signalling

Self Cite

130

“…The PE2 region E box is a docking site for USF1 and -2. A) Occupancy of the immediate 599 upstream SBEs with SMAD2, 3, and 4 and complex formation with p53 is required for TGF-b1-induced PAI-1 expression (73,(122)(123)(124). The Mad homology (MH) 1 domain of SMAD2, 3, and 4 contains a b-hairpin structure for binding to DNA, although SMAD2 has a relatively low affinity for the SBE.…”

Section: Discussionmentioning

confidence: 99%

“…USF2 occupancy of the PAI-1 promoter proximal E box 2 (PE2) region E box (CACGTG) site, which adjoins the 3 59 SMAD binding elements (SBEs) that mediate TGF-b1induced gene expression ( Fig. 6A), is essential for the growth state-dependent transcriptional activation of the PAI-1 gene (71,(122)(123)(124). USF1 and -2 involvement in PAI-1 gene control has significant implications regarding both renal fibrosis and p53 function (124)(125)(126)(127)(128)(129)(130).…”

Section: Modeling P53-smad Interactions With Accessory Coactivatorsmentioning

confidence: 99%

“…6A), is essential for the growth state-dependent transcriptional activation of the PAI-1 gene (71,(122)(123)(124). USF1 and -2 involvement in PAI-1 gene control has significant implications regarding both renal fibrosis and p53 function (124)(125)(126)(127)(128)(129)(130). Indeed, USF1 directly interacts with p53 and inhibits MDM2-mediated p53 nuclear export and degradation, resulting in p53 protein stabilization (131).…”

Section: Modeling P53-smad Interactions With Accessory Coactivatorsmentioning

confidence: 99%

See 1 more Smart Citation

TGF‐β1–p53 cooperativity regulates a profibrotic genomic program in the kidney: molecular mechanisms and clinical implications

et al. 2019

Self Cite

Chronic kidney disease affects >15% of the U.S. population and >850 million individuals worldwide. Fibrosis is the common outcome of many chronic renal disorders and, although the etiology varies (i.e., diabetes, hypertension, ischemia, acute injury, and urologic obstructive disorders), persistently elevated renal TGF‐β1 levels result in the relentless progression of fibrotic disease. TGF‐β1 orchestrates the multifaceted program of renal fibrogenesis involving proximal tubular dysfunction, failed epithelial recovery and redifferentiation, and subsequent tubulointerstitial fibrosis, eventually leading to chronic renal disease. Recent findings implicate p53 as a cofactor in the TGF‐β1‐induced signaling pathway and a transcriptional coregulator of several TGF‐β1 profibrotic response genes by complexing with receptor‐activated SMADs, which are homologous to the small worms (SMA) and Drosophilia mothers against decapentaplegic (MAD) gene families. The cooperative p53‐TGF‐β1 genomic cluster includes genes involved in cell growth control and extracellular matrix remodeling [e.g., plasminogen activator inhibitor‐1 (PAI‐1; serine protease inhibitor, clade E, member 1), connective tissue growth factor, and collagen I]. Although the molecular basis for this codependency is unclear, many TGF‐β1‐responsive genes possess p53 binding motifs. p53 up‐regulation and increased p53 phosphorylation; moreover, they are evident in nephrotoxin‐ and ischemia/reperfusion‐induced injury, diabetic nephropathy, ureteral obstructive disease, and kidney allograft rejection. Pharmacologic and genetic approaches that target p53 attenuate expression of the involved genes and mitigate the fibrotic response, confirming a key role for p53 in renal disorders. This review focuses on mechanisms whereby p53 functions as a transcriptional regulator within the TGF‐β1 cluster with an emphasis on the potent fibrosis‐promoting PAI‐1 gene.—Higgins, C. E., Tang, J., Mian, B. M., Higgins, S. P., Gifford, C. C., Conti, D. J., Meldrum, K. K., Samarakoon, R., Higgins, P. J. TGF‐β1‐p53 cooperativity regulates a profibrotic genomic program in the kidney: molecular mechanisms and clinical implications. FASEB J. 33, 10596–10606 (2019). http://www.fasebj.org

“…PAI-1 limits urokinase (uPA)-mediated pericellular plasmin generation to maintain a supporting "scaffold" for cell movement [22] while also regulating uPA-dependent growth factor activation attenuating, thereby, the associated proliferative response [13]. Using the sequence restraints for PAI-1 promoter-driven reporter activation [25] and DNA binding [11], a double-stranded 45-bp PE2 DNA construct was designed based on the requirements for an intact CACGTG motif for probe recognition by USF [11,24]. Transfection of these double-stranded USF binding, "decoys" effectively reduced both serum-and TGF-β1-induced PAI-1 transcript levels in HaCaT II-4 keratinocytes (Figure 2).…”

Section: Ape2 Region Decoy Effectively Attenuates Tgf-β1-induced Pai-mentioning

confidence: 99%

PAI-1 Promoter-specific Oligonucleotide Decoys: Transcription Factor “Bates” and Potential Utility as Wound Healing Therapeutics

Higgins¹

2014

Cell Dev Biol

IntroductionDouble-strand Oligo DeoxyNucleotides (ODNs) or hairpin ODNs that mimic binding sites for transcription factors are effective ciselement decoys. These short (15-30 mer) platforms are designed to contain protein-binding consensus recognition sites or modified sequences permissive for stronger protein-DNA interactions [1]. Transfected decoys bind construct-specific transcriptional effectors effectively titrating trans-acting factors from their target promoters. Sp1, AP-1, STAT3, and Ets-1 decoys inhibit expression of cancerassociated genes as well as attenuate tumor cell growth and metastasis [2][3][4][5]. Despite similarity in the consensus binding sequences between STAT1 and STAT3, a decoy was developed that specifically sequesters STAT3 but not STAT1 [6], demonstrating the feasibility of differential discrimination among closely-related transcription factors. While decoy delivery in vivo is major challenge for clinical applications, recent findings highlight the utility and advantages of ODN technologies in animal model systems [7,8] including specific modifications (i.e., incorporation of phosphorothioate groups) to increase stability. Recent advances include development of circularized or "block" decoys which are chimeric constructs that target multiple regulatory elements [9]. The USF/PAI-1 Axis as a ModelUpstream stimulatory factor-1 and -2 (USF1/2) are basic helixloop-helix/leucine zipper (bHLHLZ) E box-binding transcription factors the functions of which are dependent on site-specific phosphorylation. Dimer composition and recruited co-factors dictate target gene expression [10][11][12]. USF1/2 regulate growth statedependent transcription of plasminogen activator inhibitor-1 (PAI-1, SERPINE1) [11], a major TGF-β1-responsive and p53 target gene [13,14]. PAI-1 controls pericellular plasmin generation and is a prominent member of the "wound-response" transcriptome [15,16]. PAI-1 is required for TGF-β1-stimulated keratinocyte planar migration and stromal barrier invasion likely via LRP1-mediated engagement of the Jak/Stat pathway [14,17]. This SERPIN is a nonstructural Extracellular Matrix (ECM)-associated (matricellular) protein [18] that promotes a mesenchymal-to-amoeboid transition with activation of a intracellular signaling cascade required for efficient 3-D "stromal" migration [19,20]. The consistent association of PAI-1 expression with the global program of tissue injury [21] suggests that this SERPIN integrates cycles of cell-to-substrate adhesion/dis-adhesion with repair "scaffold" remodeling to meet the requirements for effective cellular migration [22]. A recent assessment of the transcriptional signature among the spectrum of wound healing responses (i.e., non-scarring regenerative repair, scar formation, chronic non-healing injuries) clearly indicated that PAI-1 partitioned to the dysfunctional healing gene set repertoire [23] emphasizing its candidacy as a translationally-important target in the context of tissue repair anomalies associated with deficient or excessive PAI-1 levels [21...