Activation of CFTR by UCCF-029 and genistein

Recommended Tool Compounds for Modifying the Cystic Fibrosis Transmembrane Conductance Regulator Channel Variants

Cystic fibrosis (CF) is a genetic disorder arising from variations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, leading to multiple organ system defects. CFTR tool compounds are molecules that can modify the activity of the CFTR channel. Especially, patients that are currently not able to benefit from approved CFTR modulators, such as patients with rare CFTR variants, benefit from further research in discovering novel tools to modulate CFTR. This Review explores the development and classification of CFTR tool compounds, including CFTR blockers (CFTRinh-172, GlyH-101), potentiators (VRT-532, Genistein), correctors (VRT-325, Corr-4a), and other approved and unapproved modulators, with detailed descriptions and discussions for each compound. The challenges and future directions in targeting rare variants and optimizing drug delivery, and the potential synergistic effects in combination therapies are outlined. CFTR modulation holds promise not only for CF treatment but also for generating CF models that contribute to CF research and potentially treating other diseases such as secretory diarrhea. Therefore, continued research on CFTR tool compounds is critical.

Overview of CFTR activators and their recent studies for dry eye disease: a review

The cystic fibrosis transmembrane conductance regulator (CFTR) gets activated via the cAMP signaling pathway and is present in various secretory epithelial cells, including conjunctival and corneal epithelial cells. Activation of CFTR leads to fluid secretion in both mouse and human ocular surfaces. Dry eye disease is a significant health problem for which limited therapeutic options are available. In this review, on the one hand, small molecule CFTR activators with different chemical structures are summarized, and on the other hand, the pharmacological activity test and structural optimization of small molecule CFTR activators in the treatment of dry eye are outlined. The purpose of this review is to highlight the important role of CFTR activators in the treatment of dry eye disease and their potential as a new strategy for the treatment of dry eye disease.

Therapeutic potential of phytochemicals for cystic fibrosis

The aim of this review was to review and discuss various phytochemicals that exhibit beneficial effects on mutated membrane channels, and hence, improve transmembrane conductance. These therapeutic phytochemicals may have the potential to decrease mortality and morbidity of CF patients. Four databases were searched using keywords. Relevant studies were identified, and related articles were separated. Google Scholar, as well as gray literature (i.e., information that is not produced by commercial publishers), were also checked for related articles to locate/identify additional studies. The relevant databases were searched a second time to ensure that recent studies were included. In conclusion, while curcumin, genistein, and resveratrol have demonstrated effectiveness in this regard, it should be emphasized that coumarins, quercetin, and other herbal medicines also have beneficial effects on transporter function, transmembrane conductivity, and overall channel activity. Additional in vitro and in vivo studies should be conducted on mutant CFTR to unequivocally define the mechanism by which phytochemicals alter transmembrane channel function/activity, since the results of the studies evaluated in this review have a high degree of heterogenicity and discrepancy. Finally, continued research be undertaken to clearly define the mechanism(s) of action and the therapeutic effects that therapeutic phytochemicals have on the symptoms observed in CF patients in an effort to reduce mortality and morbidity.

Genistein Activates Transcription Factor EB and Corrects Niemann-Pick C Phenotype

Niemann-Pick type C disease (NPCD) is a lysosomal storage disease (LSD) characterized by abnormal cholesterol accumulation in lysosomes, impaired autophagy flux, and lysosomal dysfunction. The activation of transcription factor EB (TFEB), a master lysosomal function regulator, reduces the accumulation of lysosomal substrates in LSDs where the degradative capacity of the cells is compromised. Genistein can pass the blood-brain barrier and activate TFEB. Hence, we investigated the effect of TFEB activation by genistein toward correcting the NPC phenotype. We show that genistein promotes TFEB translocation to the nucleus in HeLa TFEB-GFP, Huh7, and SHSY-5Y cells treated with U18666A and NPC1 patient fibroblasts. Genistein treatment improved lysosomal protein expression and autophagic flux, decreasing p62 levels and increasing those of the LC3-II in NPC1 patient fibroblasts. Genistein induced an increase in β-hexosaminidase activity in the culture media of NPC1 patient fibroblasts, suggesting an increase in lysosomal exocytosis, which correlated with a decrease in cholesterol accumulation after filipin staining, including cells treated with U18666A and NPC1 patient fibroblasts. These results support that genistein-mediated TFEB activation corrects pathological phenotypes in NPC models and substantiates the need for further studies on this isoflavonoid as a potential therapeutic agent to treat NPCD and other LSDs with neurological compromise.

Estrogen and estrogen receptors in the modulation of gastrointestinal epithelial secretion

Gastrointestinal (GI) epithelial ion transport is physiologically important in many aspects of humans, such as in maintaining fluid balance of whole body, and also plays a role in the development and progression of common GI disease. Estrogen and estrogen receptors have been shown to modulate the activity of epithelial ion secretion in GI tract. This review aims to address the current state of knowledge about the role of estrogen and estrogen receptors in modulation of GI epithelial secretion and to elucidate the underlying mechanisms. We highlight the recent findings regarding the importance of estrogen and estrogen receptors in GI epithelia protection and body fluid balance by modulation of gastrointestinal epithelial HCO₃^- and Cl^- secretion, especially current information about the regulatory mechanisms of duodenal HCO₃^- secretion based on our study in this field. Since there are no reviews on this topic but only few papers to address the main issues, we hope to timely provide new perspectives for the association between estrogen and GI disease.

Natural Compounds as Therapeutic Agents in the Treatment Cystic Fibrosis

The recent FDA approval of two drugs to treat the basic defect in cystic fibrosis has given hope to patients and their families battling this devastating disease. Over many years, with heavy financial investment from Vertex Pharmaceuticals and the Cystic Fibrosis Foundation, pre-clinical evaluation of thousands of synthetic drugs resulted in the production of Kalydeco and Orkambi. Yet, despite the success of this endeavor, many other compounds have been proposed as therapeutic agents in the treatment of CF. Of note, several of these compounds are naturally occurring, and are present in spices from the grocery store and over the counter preparations in health food stores. In this short review, we look at three such compounds, genistein, curcumin, and resveratrol, and evaluate the scientific support for their use as therapeutic agents in the treatment of patients with CF.

Decreased expression of cystic fibrosis transmembrane conductance regulator impairs sperm quality in aged men

Sperm quality declines with aging; however, the underlying molecular mechanism remains elusive. The cystic fibrosis transmembrane conductance regulator (CFTR) has been shown to play an essential role in fertilizing capacity of sperm and male fertility. This study aimed to investigate the involvement of age-dependent CFTR downregulation in lowering sperm quality in old age. Two hundred and one healthy fertile men of three age groups (20-40 years, n=64; 40-60 years, n=61; and >60 years, n=76) were recruited. Expression of CFTR was determined by RT-PCR, western blot, and immunofluorescence staining. Collected sperm were treated with CFTR inhibitor or potentiator. Sperm quality was assessed by motility and bicarbonate-induced capacitation. The results showed that the expression of CFTR on the equatorial segment and neck region of sperm was significantly decreased in an age-dependent manner. Reduction of CFTR expression in sperm from old men was correlated with lowered forward motility and decreased HCO3(-) sensitivity required for sperm capacitation. Activation of CFTR by genistein partially rescued the decreased forward motility in sperm from old men. Decreased CFTR expression in sperm was also found to be associated with lowered sperm quality in aging mice. These results suggest that age-dependent downregulation of CFTR in sperm leads to lowered sperm quality in old age sperm. CFTR may be a pontential target for rescuing sperm motility as well as a fertility indicator in old age men.

Genistein stimulates duodenal HCO(3)(-) secretion through PI3K pathway in mice

Genistein has been proposed as a promising pharmacotherapeutic for cystic fibrosis. We recently found that genistein stimulates murine duodenal HCO(3)(-) secretion through cystic fibrosis transmembrane conductance regulator (CFTR). The aim of the present study was to determine the intracellular signal pathways involved in genistein-stimulated duodenal HCO(3)(-) secretion. Murine duodenal mucosal HCO(3)(-) secretion was examined in vitro in Ussing chambers by the pH-stat technique. The results showed that neither cAMP-dependent signal pathway inhibitors MDL-12330A and KT-5720, nor cGMP signal pathway inhibitors NS2028 and KT5823, nor calcium signal pathway inhibitors verapamil and W-13, altered genistein-stimulated duodenal HCO(3)(-) secretion. In calcium-free solution, genistein-stimulated duodenal HCO(3)(-) secretion was not altered either. Vanadate, an inhibitor of protein tyrosine phosphatase, only partially inhibited genistein-stimulated duodenal HCO(3)(-) secretion. However, both wortmannin and LY294002, two structurally and mechanistically distinct phosphatidylinositol 3-kinase (PI3K) inhibitors, markedly inhibited genistein-stimulated duodenal HCO(3)(-) secretion. Genistein increased duodenal mucosal PI3K activity and induced the phosphorylation of Akt, a signaling molecule downstream of PI3K, which was again inhibited by wortmannin. Estrogen receptor antagonist, ICI182,780, also markedly inhibited genistein-stimulated duodenal HCO(3)(-) secretion and genistein-induced PI3K activity increase in duodenal mucosa. These results demonstrate that genistein stimulates duodenal HCO(3)(-) secretion mainly through estrogen receptor and PI3K-dependent pathway. These findings contribute to the understanding of the molecular mechanism of genistein-induced anion secretion and further pharmacotherapeutic development and use of genistein or related substances in the treatment of diseases of epithelial tissues.

Genistein: a natural isoflavone with a potential for treatment of genetic diseases

Genistein [4′,5,7-trihydroxyisoflavone or 5,7-dihydroxy-3-(4-hydroxyphenyl)-4H-1-benzopyran-4-one] is a natural isoflavone occurring in many plants known to possess various biological activities, ranging from phyto-oestrogenic to antioxidative actions. Recent studies indicated that this isoflavone can also be considered as a drug for as yet untreatable genetic diseases. In the present review, we discuss a plausible use of genistein in treatment of two genetic disorders: CF (cystic fibrosis) and MPS (mucopolysaccharidosis). Although various biological actions of genistein are employed in these two cases, in vitro studies, tests on animal models and pilot clinical trials suggest that this plant-derived compound might be a real hope for patients suffering from severe inherited disorders with relatively complicated pathomechanisms, including those affecting the central nervous system.

Genistein stimulates electrogenic Cl− secretion via phosphodiesterase modulation in the mouse jejunum

Previously, we demonstrated that genistein stimulated Cl− secretion in the mouse jejunum (Baker MJ and Hamilton KL, Am J Physiol Cell Physiol 287: C1636–C1645, 2004); however, the mode of action of genistein still remains unclear. Here, we examined the activation of Cl− secretion by the modulation of phosphodiesterases (PDEs) by genistein (75 μM) in the mouse jejunum with the Ussing short-circuit current ( Isc) technique. Drugs tested included theophylline (10 mM), a nonspecific PDE inhibitor; 8-methoxymethyl-3-isobutyl-1-methylxanthine (8-MM-IBMX; 100 μM), erythro-9-(2-hydroxyl-3-nonyl)-adenine (EHNA; 40 μM), milrinone (100 μM), and rolipram (40 and 100 μM), which are specific inhibitors of PDE1–PDE4, respectively. Theophylline stimulated a bumetanide-sensitive Isc, indicative of Cl− secretion, and abolished genistein's stimulatory action on Isc. Neither 8-MM-IBMX nor EHNA altered the basal Isc nor did these PDE inhibitors affect the stimulatory action of genistein on the Isc of the mouse jejunum. Rolipram had no effect on basal Isc, but it reduced the genistein-stimulated Isc compared with time-matched control tissues. Milrinone stimulated a concentration-dependent increase in Isc. Bumetanide (10 μM) inhibited 60 ± 4% of milrinone-induced Isc. Pretreating tissues with milrinone prevented genistein from stimulating Isc, and pretreatment with genistein reduced the effect of milrinone on Isc. H89 (50 μM), a PKA inhibitor, reduced the milrinone-stimulated Isc. Likewise, H89 reduced the genistein-stimulated Isc. Here, we demonstrate, for the first time, that genistein activates Cl− secretion of the mouse jejunum via inhibition of a PDE3-dependent pathway.