FK506-binding protein 12 ligands: a patent review

Simultaneous determination of HD56, a novel prodrug, and its active metabolite in cynomolgus monkey plasma using LC-MS/MS for elucidating its pharmacokinetic profile

An LC-MS/MS method was developed and validated for the simultaneous determination of the carboxylic acid ester precursor HD56 and the active product HD561 in cynomolgus monkey plasma. Then, the pharmacokinetic characteristics of both compounds following single and multiple i.g. administrations in cynomolgus monkeys were elucidated. In the method, chromatographic separation was achieved with a C18 reversed-phase column and the target quantification was carried out by an electrospray ionization (ESI) source coupled with triple quadrupole mess detector in positive ionization mode with multiple reaction monitoring (MRM) approach. Using the quantification method, the in vitro stability of HD56 in plasma and HD56 pharmacokinetic behavior after i.g. administration in cynomolgus monkey were investigated. It was approved that HD56 did convert into HD561 post-administration. The overall systemic exposure of HD561 post-conversion from HD56 accounted for only about 17% of HD56. After repeated administration at the same dose, there was no significant difference in exposure levels of both HD56 and HD561. However, after multiple dosing, the exposure of HD56 tended to decrease while that of HD561 tended to increase, resulting in a 30% in the exposure ratio. Remarkably, with a carboxylesterase (CES) activity profile akin to humans, the observed in vivo pharmacokinetic profile in cynomolgus monkeys holds promise for predicting HD56/HD561 PK profiles in humans.

The prognostic and immunological role of FKBP1A in an integrated muti-omics cancers analysis, especially lung cancer

BACKGROUND AND AIM

FKBP1A, a gene encoding the FK506-binding protein 1A, has emerged as a significant player in cancer progression and prognosis. This study aimed to comprehensively investigate the multifaceted role of FKBP1A in cancer, focusing on its differential expression patterns, prognostic implications, genetic alterations, and associations with the tumor microenvironment.

METHODS AND RESULTS

Using large-scale datasets, including GTEx, TCGA, HPA, and cBioPortal, we analyzed FKBP1A expression across normal tissues and various cancer types. Our findings revealed that FKBP1A exhibited aberrant upregulation in most human cancers, making it a potential biomarker for malignancy. Moreover, FKBP1A expression correlated with poor overall survival, disease-specific survival, disease-free interval, and progression-free interval in several cancers, indicating its prognostic significance. Genetic alteration analysis showed that FKBP1A gene amplification was prevalent, particularly in ovarian cancer. Furthermore, FKBP1A expression was associated with tumor mutational burden and microsatellite instability, highlighting its potential involvement in tumor-immune response. Notably, FKBP1A expression positively correlated with stromal and immune cell scores, suggesting its role in shaping the tumor microenvironment. Additionally, according to the functional enrichment analysis, experimental validation in lung adenocarcinoma confirmed the role of FKBP1A through the regulation of EGFR signaling by apoptosis, which is consistent with drug sensitivity analysis to some extent.

CONCLUSION

In conclusion, FKBP1A exhibits differential expression in cancer, serves as a prognostic indicator, undergoes genetic alterations, and influences the tumor-immune microenvironment. These findings shed light on the multifaceted role of FKBP1A in cancer development and progression, suggesting its potential as a therapeutic target and guidance of clinical drugs selection, and provide valuable insights into patient prognosis for interventions based on pharmaceuticals.

Double-reporter-guided targeted activation of the oxytetracycline silent gene cluster in Streptomyces rimosus M527

In Streptomyces rimosus M527, the oxytetracycline (OTC) biosynthetic gene cluster is not expressed under laboratory conditions. In this study a reported-guided mutant selection (RGMS) procedure was used to activate the cluster. The double-reporter plasmid pAGT was constructed in which gusA encoding a β-glucuronidase and tsr encoding a thiostrepton resistance methyltransferase were placed under the control of the native promoter of oxyA gene (P_oxyA ). Plasmid pAGT was introduced and integrated into the chromosome of S. rimosus M527 by conjugation, yielding initial strain M527-pAGT. Subsequently, mutants of M527-pAGT were generated by using ribosome engineering technology. The mutants harboring activated OTC gene cluster were selected based on visual observation of GUS activity and thiostrepton resistance. Finally, mutant M527-pAGT-R7 was selected producing OTC in a concentration of 235.2 mg/L. In this mutant transcriptional levels of oxy_sr genes especial oxyA_sr gene were increased compared to wild-type strain S. rimosus M527. The mutant M527-pAGT-R7 showed antagonistic activities against Gram-negative and Gram-positive strains. All data indicate that the OTC gene cluster was successfully activated using the RGMS method.

Mounting evidence of FKBP12 implication in neurodegeneration

Intrinsically disordered proteins, such as tau or α-synuclein, have long been associated with a dysfunctional role in neurodegenerative diseases. In Alzheimer's and Parkinson's' diseases, these proteins, sharing a common chemical-physical pattern with alternating hydrophobic and hydrophilic domains rich in prolines, abnormally aggregate in tangles in the brain leading to progressive loss of neurons. In this review, we present an overview linking the studies on the implication of the peptidyl-prolyl isomerase domain of immunophilins, and notably FKBP12, to a variety of neurodegenerative diseases, focusing on the molecular origin of such a role. The involvement of FKBP12 dysregulation in the aberrant aggregation of disordered proteins pinpoints this protein as a possible therapeutic target and, at the same time, as a predictive biomarker for early diagnosis in neurodegeneration, calling for the development of reliable, fast and cost-effective detection methods in body fluids for community-based screening campaigns.

A modular DNA scaffold to study protein-protein interactions at single-molecule resolution

The residence time of a drug on its target has been suggested as a more pertinent metric of therapeutic efficacy than the traditionally used affinity constant. Here, we introduce junctured-DNA tweezers as a generic platform that enables real-time observation, at the single-molecule level, of biomolecular interactions. This tool corresponds to a double-strand DNA scaffold that can be nanomanipulated and on which proteins of interest can be engrafted thanks to widely used genetic tagging strategies. Thus, junctured-DNA tweezers allow a straightforward and robust access to single-molecule force spectroscopy in drug discovery, and more generally in biophysics. Proof-of-principle experiments are provided for the rapamycin-mediated association between FKBP12 and FRB, a system relevant in both medicine and chemical biology. Individual interactions were monitored under a range of applied forces and temperatures, yielding after analysis the characteristic features of the energy profile along the dissociation landscape.

Effect of Different Doses and Times of FK506 on Different Areas of the Hippocampus in the Rat Model of Transient Global Cerebral Ischemia-Reperfusion

Background

Stroke is a major worldwide problem that is leading to a high mortality rate in humans. Ischemia, as the most common type of stroke, is characterized by tissue damage that can occur due to insufficient blood flow to the brain even for a brief duration, leading to the release of inflammatory factors, cytokines, and free radicals. In this study, we investigated the effective dose and injection time of FK506 as an immunophilin ligand for providing a suitable effect on cells of CA2, CA3, and dentate gyrus of the hippocampus.

Methods

In this in vivo study, a total of 48 male Wistar rats were divided into nine groups. The ischemia model was induced by the ligation of bilateral common carotid arteries. The doses of FK506 (3, 6, and 10 mg/kg) were administered intravenously (IV) at the beginning of reperfusion, followed by repeated injections (10 mg/kg) at 6, 24, 48, and 72 hours after ischemia, respectively. Brains were removed and prepared for Nissl staining and the TdT-mediated dUTP Nick End Labeling method.

Results

Data showed that global ischemia did not decrease the number of viable pyramidal cells in CA2 and CA3 regions, but significant differences were observed in the number of viable granular cells and apoptotic bodies in the dentate gyrus between the control and ischemia groups. Repeated doses of 6 mg/kg of FK506 at an interval of 48 hours were deemed to be the suitable dose and best time of injection.

Conclusions

It seems that FK506 can ameliorate the extent of apoptosis and may be a good candidate for the treatment of ischemia-induced brain damage.

Tacrolimus-induced severe headache associated with diffuse leukoencephalopathy: Evidence for an immune-mediated pathogenesis

Tacrolimus-induced encephalopathy presents with acute neurological symptoms such as headache, seizures, visual disturbances, hemiplegia, and altered mental status. A 60-year-old woman, presented to our clinic with a 4-month history of severe headache. She recently underwent kidney transplantation and was taking tacrolimus. MRI scan showed diffuse and symmetric alterations involving both supratentorial and infratentorial white matter. Cerebral spinal fluid assessment for infectious diseases were negative but elevated total protein level and oligoclonal bands positivity were reported. Treatment with steroid bolus, along with tacrolimus tapering, provided clinico-radiological improvement. This is the first case of tacrolimus-induced neurotoxicity strongly suggestive of an immune-mediated pathogenesis.

Fluorescence Polarization Assay for Small Molecule Screening of FK506 Biosynthesized in 96-Well Microtiter Plates

The fluorescence polarization (FP) assay has been widely used to study enzyme kinetics, antibody-antigen interactions, and other biological interactions. We propose that the FP assay can be adapted as a high-throughput and potentially widely applicable screen for small molecules. This is useful in metabolic engineering, which is a promising approach to synthesizing compounds of pharmaceutical, agricultural, and industrial importance using bioengineered strains. There, the development of high-yield strains is often a costly and time-consuming process. This problem can be addressed by generating and testing large mutant strain libraries. However, a current key bottleneck is the lack of high-throughput screens to detect the small molecule products. The FP assay is quantitative, sensitive, fast, and cheap. As a proof of principle, we established the FP assay to screen for FK506 (tacrolimus) produced by Streptomyces tsukubaensis, which was cultivated in 96-well plates. An ultraviolet mutagenized library of 160 colonies was screened to identify strains showing higher FK506 productivities. The FP assay has the potential to be generalized to detect a wide range of other small molecules.

Total chemical synthesis, refolding, and crystallographic structure of fully active immunophilin calstabin 2 (FKBP12.6)

Synthetic biology (or chemical biology) is a growing field to which the chemical synthesis of proteins, particularly enzymes, makes a fundamental contribution. However, the chemical synthesis of catalytically active proteins (enzymes) remains poorly documented because it is difficult to obtain enough material for biochemical experiments. We chose calstabin, a 107-amino-acid proline isomerase, as a model. We synthesized the enzyme using the native chemical ligation approach and obtained several tens of milligrams. The polypeptide was refolded properly, and we characterized its biophysical properties, measured its catalytic activity, and then crystallized it in order to obtain its tridimensional structure after X-ray diffraction. The refolded enzyme was compared to the recombinant, wild-type enzyme. In addition, as a first step of validating the whole process, we incorporated exotic amino acids into the N-terminus. Surprisingly, none of the changes altered the catalytic activities of the corresponding mutants. Using this body of techniques, avenues are now open to further obtain enzymes modified with exotic amino acids in a way that is only barely accessible by molecular biology, obtaining detailed information on the structure-function relationship of enzymes reachable by complete chemical synthesis.

TWISTED DWARF 1 Associates with BRASSINOSTEROID-INSENSITIVE 1 to Regulate Early Events of the Brassinosteroid Signaling Pathway

A genome-wide screen for mutants showing altered brassinosteroid (BR) sensitivity or bri1-like phenotypes resulted in the identification of two new mutant alleles of TWISTED DWARF 1 (TWD1), twd1-4, and twd1-5. Previous studies indicated that TWD1, also named as ULTRACURVATA 2 or FKBP42, associates with auxin efflux transporters and is essential for their biological functions. Although earlier reports showed that BR signaling is downregulated in twd1, how TWD1 is integrated in BR signaling has not been elucidated. Here, we provide genetic and biochemical evidence demonstrating that TWD1 interacts with the BR receptor BRI1 in vivo in a BR-independent manner. Further analyses indicated that TWD1 modulates the BR signal transduction not by altering ER quality control or protein abundance of BRI1; instead, TWD1 appears to be critical in BR-induced interaction of BRI1 and its co-receptor BAK1, as well as BR-induced phosphorylation of these two proteins. These results provide better understanding of the early events of the BR signaling pathway.

mTOR inhibitor temsirolimus and MEK1/2 inhibitor U0126 promote chromosomal instability and cell type-dependent phenotype changes of glioblastoma cells

The phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) and the RAF/mitogen-activated and extracellular signal-regulated kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling pathways are frequently deregulated in cancer. Temsirolimus (TEM) and its primary active metabolite rapamycin allosterically block mTOR complex 1 substrate recruitment. The context-/experimental setup-dependent opposite effects of rapamycin on the multiple centrosome formation, aneuploidy, DNA damage/repair, proliferation, and invasion were reported. Similarly, the context-dependent either tumor-promoting or suppressing effects of RAF-MEK-ERK pathway and its inhibitors were demonstrated. Drug treatment-mediated stress may promote chromosomal instability (CIN), accelerating changes in the genomic landscape and phenotype diversity. Here, we characterized the genomic and phenotypic changes of U251 and T98G glioblastoma cell lines long-term treated with TEM or U0126, an inhibitor of MEK1/2. TEM significantly increased clonal and non-clonal chromosome aberrations. Both TEM and U0126 affected copy number alterations (CNAs) pattern. A proliferation rate of U251TEM and U251U0126 cells was lower and higher, respectively, than control cells. Colony formation efficiency of U251TEM significantly decreased, whereas U251U0126 did not change. U251TEM and U251U0126 cells decreased migration. In contrast, T98GTEM and T98GU0126 cells did not change proliferation, colony formation efficiency, and migration. Changes in the sensitivity of inhibitor-treated cells to the reduction of the glucose concentration were observed. Our results suggest that CIN and adaptive reprogramming of signal transduction pathways may be responsible for the cell type-dependent phenotype changes of long-term TEM- or U0126-treated tumor cells.

Airway response to sirolimus therapy for the treatment of complex pediatric lymphatic malformations

Head and neck lymphatic malformations can create airway management challenges requiring tracheotomy. Sirolimus, an inhibitor of mammalian target of rapamycin (mTOR), may inhibit growth of lymphatic malformations. We describe two patients born with large lymphatic malformations with improved airway symptoms following sirolimus therapy. Patient #1 underwent tracheotomy and multi-modal therapy including sirolimus with reduction in airway involvement but regrowth after discontinuation of sirolimus. Patient #2 also experienced a significant response to sirolimus allowing for extubation and discharge without tracheotomy. Early initiation of sirolimus therapy should be considered as a means to avoid tracheotomy in complex head and neck lymphatic malformations.

Peptidyl-prolyl isomerases: functionality and potential therapeutic targets in cardiovascular disease

Peptidyl-prolyl cis/trans isomerases (PPIases) are a conserved group of enzymes that catalyse the conversion between cis and trans conformations of proline imidic peptide bonds. These enzymes play critical roles in regulatory mechanisms of cellular function and pathophysiology of disease. There are three different classes of PPIases and increasing interest in the development of specific PPIase inhibitors. Cyclosporine A, FK506, rapamycin and juglone are known PPIase inhibitors. Herein, we review recent advances in elucidating the role and regulation of the PPIase family in vascular disease. We focus on peptidyl-prolyl cis/trans isomerase NIMA-interacting 1 (Pin1), an important member of the PPIase family that plays a role in cell cycle progression, gene expression, cell signalling and cell proliferation. In addition, Pin1 may be involved in atherosclerosis. The unique role of Pin1 as a molecular switch that impacts on multiple downstream pathways necessitates the evaluation of a highly specific Pin1 inhibitor to aid in potential therapeutic drug discovery.

Pitfalls of the MTT assay: Direct and off-target effects of inhibitors can result in over/underestimation of cell viability

The MTT assay (to a less degree MTS, XTT or WST) is a widely exploited approach for measuring cell viability/drug cytotoxicity. MTT reduction occurs throughout a cell and can be significantly affected by a number of factors, including metabolic and energy perturbations, changes in the activity of oxidoreductases, endo-/exocytosis and intracellular trafficking. Over/underestimation of cell viability by the MTT assay may be due to both adaptive metabolic and mitochondrial reprogramming of cells subjected to drug treatment-mediated stress and inhibitor off-target effects. Previously, imatinib, rottlerin, ursolic acid, verapamil, resveratrol, genistein nanoparticles and some polypeptides were shown to interfere with MTT reduction rate resulting in inconsistent results between the MTT assay and alternative assays. Here, to test the under/overestimation of viability by the MTT assay, we compared results derived from the MTT assay with the trypan blue exclusion assay after treatment of glioblastoma U251, T98G and C6 cells with three widely used inhibitors with the known direct and side effects on energy and metabolic homeostasis - temozolomide (TMZ), a DNA-methylating agent, temsirolimus (TEM), an inhibitor of mTOR kinase, and U0126, an inhibitor of MEK1/2 kinases. Inhibitors were applied shortly as in IC50 evaluating studies or long as in studies focusing on drug resistance acquisition. We showed that over/underestimation of cell viability by the MTT assay and its significance depends on a cell line, a time point of viability measurement and other experimental parameters. Furthermore, we provided a comprehensive survey of factors that should be accounted in the MTT assay. To avoid result misinterpretation, supplementation of the tetrazolium salt-based assays with other non-metabolic assays is recommended.

Evaluation of WO2011045166A1, Fkbp52-tau interaction as a novel therapeutical target for treating the neurological disorders involving tau dysfunction

INTRODUCTION

This invention provides the screening methods of candidate compounds, the diagnostic methods and the methods of treatment of human cognitive diseases, and also gives out several potential candidate compounds. The invention establishes that the FKBP52-Tau interaction provides a new target that may be used advantageously for novel therapeutic approaches for neurological disorders involving Tau dysfunction, and especially for Alzheimer's disease.

AREAS COVERED

The invention generally relates to neuroprotection and repair in neurological disorders involving Tau dysfunction (including Alzheimer's disease). The invention describes a direct interaction between FKBP52 and Tau, the screening methods for molecules acting on the FKBP52-Tau interaction, in order to modulate the detrimental effect of pathogenic Tau. Finally, it discusses therapeutic, diagnostic, prognostic and monitoring assays of neurological disorders involving Tau dysfunction.

EXPERT OPINION

Several methods or techniques were used to determine the validity of screening methods, involving biochemistry, immunology, fluorescence analysis and cell experiment. Candidate compounds mentioned in the patent include FK506 derivatives, rapamycin derivatives and pipecolyl-α-keto-amid compounds. However, the mechanism, the structural similarity and the biological activity were unmentioned, which may partly reduce the practicability of the invention. The FKBP52-Tau interaction as a novel target for neurodegenerative diseases is promising. FKBP52 is capable of preventing polymerization of tubulin and maintaining axonal transport. In AD patients' brain, the high level of Tau protein phosphorylation is directly related to the decrease of FKBP52. The FKBP52-Tau interaction may provide a new critical path for treatment of neurodegenerative diseases, and new molecules will possess higher affinity and efficiency.

Biological relevance of Hsp90-binding immunophilins in cancer development and treatment

Immunophilins are a family of intracellular receptors for immunosuppressive drugs. Those immunophilins that are related to immunosuppression are the smallest proteins of the family, i.e., FKBP12 and CyPA, whereas the other members of the family have higher molecular weight because the show additional domains to the drug-binding site. Among these extra domains, the TPR-domain is perhaps the most relevant because it permits the interaction of high molecular weight immunophilins with the 90-kDa heat-shock protein, Hsp90. This essential molecular chaperone regulates the biological function of several protein-kinases, oncogenes, protein phosphatases, transcription factors and cofactors . Hsp90-binding immunophilins where first characterized due to their association with steroid receptors. They regulate the cytoplasmic transport and the subcellular localization of these and other Hsp90 client proteins, as well as transcriptional activity, cell proliferation, cell differentiation and apoptosis. Hsp90-binding immunophilins are frequently overexpressed in several types of cancers and play a key role in cell survival. In this article we analyze the most important biological actions of the best characterized Hsp90-binding immunophilins in both steroid receptor function and cancer development and discuss the potential use of these immunophilins for therapeutic purposes as potential targets of specific small molecules.