The 90-kDa heat-shock protein (Hsp90)-binding immunophilin FKBP51 is a mitochondrial protein that translocates to the nucleus to protect cells against oxidative stress

The Role of FKBPs in Complex Disorders: Neuropsychiatric Diseases, Cancer, and Type 2 Diabetes Mellitus

Stress is a common denominator of complex disorders and the FK-506 binding protein (FKBP)51 plays a central role in stress. Hence, it is not surprising that multiple studies imply the involvement of the FKBP51 protein and/or its coding gene, FKBP5, in complex disorders. This review summarizes such reports concentrating on three disorder clusters-neuropsychiatric, cancer, and type 2 diabetes mellitus (T2DM). We also attempt to point to potential mechanisms suggested to mediate the effect of FKBP5/FKBP51 on these disorders. Neuropsychiatric diseases considered in this paper include (i) Huntington's disease for which increased autophagic cellular clearance mechanisms related to decreased FKBP51 protein levels or activity is discussed, Alzheimer's disease for which increased FKBP51 activity has been shown to induce Tau phosphorylation and aggregation, and Parkinson's disease in the context of which FKBP12 is mentioned; and (ii) mental disorders, for which significant association with the single nucleotide polymorphism (SNP) rs1360780 of FKBP5 intron 7 along with decreased DNA methylation were revealed. Since cancer is a large group of diseases that can start in almost any organ or tissue of the body, FKBP51's role depends on the tissue type and differences among pathways expressed in those tumors. The FKBP51-heat-shock protein-(Hsp)90-p23 super-chaperone complex might function as an oncogene or as a tumor suppressor by downregulating the serine/threonine protein kinase (AKt) pathway. In T2DM, two potential pathways for the involvement of FKBP51 are highlighted as affecting the pathogenesis of the disease-the peroxisome proliferator-activated receptor-γ (PPARγ) and AKt.

Structure-based discovery of small molecule inhibitors of FKBP51-Hsp90 protein-protein interaction

The heat shock protein 90 kDa (Hsp90) molecular chaperone machinery is responsible for the folding and activation of hundreds of important clients such as kinases, steroid hormone receptors, transcription factors, etc. This process is dynamically regulated in an ATP-dependent manner by Hsp90 co-chaperones including a group of tetratricopeptide (TPR) motif proteins that bind to the C-terminus of Hsp90. Among these TPR containing co-chaperones, FK506-binding protein 51 kDa (FKBP51) is reported to play an important role in stress-related pathologies, psychiatric disorders, Alzheimer's disease, and cancer, making FKBP51-Hsp90 interaction a potential therapeutic target. In this study, we report identification of potent and selective inhibitors of FKBP51-Hsp90 protein-protein interaction using a structure-based virtual screening approach. Upon in vitro evaluation, the identified hits show a considerable degree of selectivity towards FKBP51 over other TPR proteins, particularly for highly homologous FKBP52. Tyr355 of FKBP51 emerged as an important contributor to inhibitor's specificity. Additionally, we demonstrate the impact of these inhibitors on cellular energy metabolism, and neurite outgrowth, which are subjects of FKBP51 regulation. Overall, the results from this study highlight a novel pharmacological approach towards regulation of FKBP51 function and more generally, Hsp90 function via its interaction with TPR co-chaperones.

Proteogenomic analysis of enriched HGSOC tumor epithelium identifies prognostic signatures and therapeutic vulnerabilities

We performed a deep proteogenomic analysis of bulk tumor and laser microdissection enriched tumor cell populations from high-grade serous ovarian cancer (HGSOC) tissue specimens spanning a broad spectrum of purity. We identified patients with longer progression-free survival had increased immune-related signatures and validated proteins correlating with tumor-infiltrating lymphocytes in 65 tumors from an independent cohort of HGSOC patients, as well as with overall survival in an additional 126 HGSOC patient cohort. We identified that homologous recombination deficient (HRD) tumors are enriched in pathways associated with metabolism and oxidative phosphorylation that we validated in independent patient cohorts. We further identified that polycomb complex protein BMI-1 is elevated in HR proficient (HRP) tumors, that elevated BMI-1 correlates with poor overall survival in HRP but not HRD HGSOC patients, and that HRP HGSOC cells are uniquely sensitive to BMI-1 inhibition.

Circulating cell-free mitochondrial DNA levels and glucocorticoid sensitivity in a cohort of male veterans with and without combat-related PTSD

Circulating cell-free mitochondrial DNA (ccf-mtDNA) is a biomarker of cellular injury or cellular stress and is a potential novel biomarker of psychological stress and of various brain, somatic, and psychiatric disorders. No studies have yet analyzed ccf-mtDNA levels in post-traumatic stress disorder (PTSD), despite evidence of mitochondrial dysfunction in this condition. In the current study, we compared plasma ccf-mtDNA levels in combat trauma-exposed male veterans with PTSD (n = 111) with those who did not develop PTSD (n = 121) and also investigated the relationship between ccf mt-DNA levels and glucocorticoid sensitivity. In unadjusted analyses, ccf-mtDNA levels did not differ significantly between the PTSD and non-PTSD groups (t = 1.312, p = 0.191, Cohen's d = 0.172). In a sensitivity analysis excluding participants with diabetes and those using antidepressant medication and controlling for age, the PTSD group had lower ccf-mtDNA levels than did the non-PTSD group (F(1, 179) = 5.971, p = 0.016, partial η2 = 0.033). Across the entire sample, ccf-mtDNA levels were negatively correlated with post-dexamethasone adrenocorticotropic hormone (ACTH) decline (r = -0.171, p = 0.020) and cortisol decline (r = -0.149, p = 0.034) (viz., greater ACTH and cortisol suppression was associated with lower ccf-mtDNA levels) both with and without controlling for age, antidepressant status and diabetes status. Ccf-mtDNA levels were also significantly positively associated with IC50-DEX (the concentration of dexamethasone at which 50% of lysozyme activity is inhibited), a measure of lymphocyte glucocorticoid sensitivity, after controlling for age, antidepressant status, and diabetes status (β = 0.142, p = 0.038), suggesting that increased lymphocyte glucocorticoid sensitivity is associated with lower ccf-mtDNA levels. Although no overall group differences were found in unadjusted analyses, excluding subjects with diabetes and those taking antidepressants, which may affect ccf-mtDNA levels, as well as controlling for age, revealed decreased ccf-mtDNA levels in PTSD. In both adjusted and unadjusted analyses, low ccf-mtDNA levels were associated with relatively increased glucocorticoid sensitivity, often reported in PTSD, suggesting a link between mitochondrial and glucocorticoid-related abnormalities in PTSD.

Knocking out Fkbp51 decreases CCl4-induced liver injury through enhancement of mitochondrial function and Parkin activity

BACKGROUND AND AIMS

Previously, we found that FK506 binding protein 51 (Fkbp51) knockout (KO) mice resist high fat diet-induced fatty liver and alcohol-induced liver injury. The aim of this research is to identify the mechanism of Fkbp51 in liver injury.

METHODS

Carbon tetrachloride (CCl4)-induced liver injury was compared between Fkbp51 KO and wild type (WT) mice. Step-wise and in-depth analyses were applied, including liver histology, biochemistry, RNA-Seq, mitochondrial respiration, electron microscopy, and molecular assessments. The selective FKBP51 inhibitor (SAFit2) was tested as a potential treatment to ameliorate liver injury.

RESULTS

Fkbp51 knockout mice exhibited protection against liver injury, as evidenced by liver histology, reduced fibrosis-associated markers and lower serum liver enzyme levels. RNA-seq identified differentially expressed genes and involved pathways, such as fibrogenesis, inflammation, mitochondria, and oxidative metabolism pathways and predicted the interaction of FKBP51, Parkin, and HSP90. Cellular studies supported co-localization of Parkin and FKBP51 in the mitochondrial network, and Parkin was shown to be expressed higher in the liver of KO mice at baseline and after liver injury relative to WT. Further functional analysis identified that KO mice exhibited increased ATP production and enhanced mitochondrial respiration. KO mice have increased mitochondrial size, increased autophagy/mitophagy and mitochondrial-derived vesicles (MDV), and reduced reactive oxygen species (ROS) production, which supports enhancement of mitochondrial quality control (MQC). Application of SAFit2, an FKBP51 inhibitor, reduced the effects of CCl4-induced liver injury and was associated with increased Parkin, pAKT, and ATP production.

CONCLUSIONS

Downregulation of FKBP51 represents a promising therapeutic target for liver disease treatment.

Sex-Specific Impact of Fkbp5 on Hippocampal Response to Acute Alcohol Injection: Involvement in Alterations of Metabolism-Related Pathways

High levels of alcohol intake alter brain gene expression and can produce long-lasting effects. FK506-binding protein 51 (FKBP51) encoded by Fkbp5 is a physical and cellular stress response gene and has been associated with alcohol consumption and withdrawal severity. Fkbp5 has been previously linked to neurite outgrowth and hippocampal morphology, sex differences in stress response, and epigenetic modification. Presently, primary cultured Fkbp5 KO and WT mouse neurons were examined for neurite outgrowth and mitochondrial signal with and without alcohol. We found neurite specification differences between KO and WT; particularly, mesh-like morphology was observed after alcohol treatment and confirmed higher MitoTracker signal in cultured neurons of Fkbp5 KO compared to WT at both naive and alcohol-treated conditions. Brain regions that express FKBP51 protein were identified, and hippocampus was confirmed to possess a high level of expression. RNA-seq profiling was performed using the hippocampus of naïve or alcohol-injected (2 mg EtOH/Kg) male and female Fkbp5 KO and WT mice. Differentially expressed genes (DEGs) were identified between Fkbp5 KO and WT at baseline and following alcohol treatment, with female comparisons possessing a higher number of DEGs than male comparisons. Pathway analysis suggested that genes affecting calcium signaling, lipid metabolism, and axon guidance were differentially expressed at naïve condition between KO and WT. Alcohol treatment significantly affected pathways and enzymes involved in biosynthesis (Keto, serine, and glycine) and signaling (dopamine and insulin receptor), and neuroprotective role. Functions related to cell morphology, cell-to-cell signaling, lipid metabolism, injury response, and post-translational modification were significantly altered due to alcohol. In summary, Fkbp5 plays a critical role in the response to acute alcohol treatment by altering metabolism and signaling-related genes.

Distinct neuroinflammatory signatures exist across genetic and sporadic amyotrophic lateral sclerosis cohorts

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive loss of upper and lower motor neurons. ALS is on a pathogenetic disease spectrum with frontotemporal dementia, referred to as ALS-frontotemporal spectrum disorder (ALS-FTSD). For mutations associated with ALS-FTSD, such as the C9orf72 hexanucleotide repeat expansion, the molecular factors associated with heterogeneity along this spectrum require further characterization. Here, using a targeted NanoString molecular barcoding approach, we interrogate neuroinflammatory dysregulation and heterogeneity at the level of gene expression in post-mortem motor cortex tissue from a cohort of clinically heterogeneous C9-ALS-FTSD cases. We identified 20 dysregulated genes in C9-ALS-FTSD, with enrichment of microglial and inflammatory response gene sets. Two genes with significant correlations to available clinical metrics were selected for validation: FKBP5, a correlate of cognitive function, and brain-derived neurotrophic factor (BDNF), a correlate of disease duration. FKBP5 and its signalling partner, NF-κB, appeared to have a cell type-specific staining distribution, with activated (i.e. nuclear) NF-κB immunoreactivity in C9-ALS-FTSD. Expression of BDNF, a correlate of disease duration, was confirmed to be higher in individuals with long compared to short disease duration using BaseScope™ in situ hybridization. Our analyses also revealed two distinct neuroinflammatory panel signatures (NPS), NPS1 and NPS2, delineated by the direction of expression of proinflammatory, axonal transport and synaptic signalling pathways. We compared NPS between C9-ALS-FTSD cases and those from sporadic ALS and SOD1-ALS cohorts and identified NPS1 and NPS2 across all cohorts. Moreover, a subset of NPS was also able to separate publicly available RNA sequencing data from independent C9-ALS and sporadic ALS cohorts into two inflammatory subgroups. Importantly, NPS subgroups did not clearly segregate with available demographic, genetic, clinical or pathological features, highlighting the value of molecular stratification in clinical trials for inflammatory subgroup identification. Our findings thus underscore the importance of tailoring therapeutic approaches based on distinct molecular signatures that exist between and within ALS-FTSD cohorts.

The transportosome system as a model for the retrotransport of soluble proteins

The classic model of action of the glucocorticoid receptor (GR) sustains that its associated heat-shock protein of 90-kDa (HSP90) favours the cytoplasmic retention of the unliganded GR, whereas the binding of steroid triggers the dissociation of HSP90 allowing the passive nuclear accumulation of GR. In recent years, it was described a molecular machinery called transportosome that is responsible for the active retrograde transport of GR. The transportosome heterocomplex includes a dimer of HSP90, the stabilizer co-chaperone p23, and FKBP52 (FK506-binding protein of 52-kDa), an immunophilin that binds dynein/dynactin motor proteins. The model shows that upon steroid binding, FKBP52 is recruited to the GR allowing its active retrograde transport on cytoskeletal tracks. Then, the entire GR heterocomplex translocates through the nuclear pore complex. The HSP90-based heterocomplex is released in the nucleoplasm followed by receptor dimerization. Subsequent findings demonstrated that the transportosome is also responsible for the retrotransport of other soluble proteins. Importantly, the disruption of this molecular oligomer leads to several diseases. In this article, we discuss the relevance of this transport machinery in health and disease.

Cumulative Exposure to Phthalates and Their Alternatives and Associated Female Reproductive Health: Body Burdens, Adverse Outcomes, and Underlying Mechanisms

The global birth rate has recently shown a decreasing trend, and exposure to environmental pollutants has been identified as a potential factor affecting female reproductive health. Phthalates have been widely used as plasticizers in plastic containers, children's toys, and medical devices, and their ubiquitous presence and endocrine-disrupting potential have already raised particular concerns. Phthalate exposure has been linked to various adverse health outcomes, including reproductive diseases. Given that many phthalates are gradually being banned, a growing number of phthalate alternatives are becoming popular, such as di(isononyl) cyclohexane-1,2-dicarboxylate (DINCH), di(2-ethylhexyl) adipate (DEHA), and di(2-ethylhexyl) terephthalate (DEHTP), and they are beginning to have a wide range of environmental effects. Studies have shown that many phthalate alternatives may disrupt female reproductive function by altering the estrous cycle, causing ovarian follicular atresia, and prolonging the gestational cycle, which raises growing concerns about their potential health risks. Herein, we summarize the effects of phthalates and their common alternatives in different female models, the exposure levels that influence the reproductive system, and the effects on female reproductive impairment, adverse pregnancy outcomes, and offspring development. Additionally, we scrutinize the effects of phthalates and their alternatives on hormone signaling, oxidative stress, and intracellular signaling to explore the underlying mechanisms of action on female reproductive health, because these chemicals may affect reproductive tissues directly or indirectly through endocrine disruption. Given the declining global trends of female reproductive capacity and the potential ability of phthalates and their alternatives to negatively impact female reproductive health, a more comprehensive study is needed to understand their effects on the human body and their underlying mechanisms. These findings may have an important role in improving female reproductive health and in turn decreasing the number of complications during pregnancy.

Mitochondrial-nuclear communication by FKBP51 shuttling

The HSP90-binding immunophilin FKBP51 is a soluble protein that shows high homology and structural similarity with FKBP52. Both immunophilins are functionally divergent and often show antagonistic actions. They were first described in steroid receptor complexes, their exchange in the complex being the earliest known event in steroid receptor activation upon ligand binding. In addition to steroid-related events, several pleiotropic actions of FKBP51 have emerged during the last years, ranging from cell differentiation and apoptosis to metabolic and psychiatric disorders. On the other hand, mitochondria play vital cellular roles in maintaining energy homeostasis, responding to stress conditions, and affecting cell cycle regulation, calcium signaling, redox homeostasis, and so forth. This is achieved by proteins that are encoded in both the nuclear genome and mitochondrial genes. This implies active nuclear-mitochondrial communication to maintain cell homeostasis. Such communication involves factors that regulate nuclear and mitochondrial gene expression affecting the synthesis and recruitment of mitochondrial and nonmitochondrial proteins, and/or changes in the functional state of the mitochondria itself, which enable mitochondria to recover from stress. FKBP51 has emerged as a serious candidate to participate in these regulatory roles since it has been unexpectedly found in mitochondria showing antiapoptotic effects. Such localization involves the tetratricopeptide repeats domains of the immunophilin and not its intrinsic enzymatic activity of peptidylprolyl-isomerase. Importantly, FKBP51 abandons the mitochondria and accumulates in the nucleus upon cell differentiation or during the onset of stress. Nuclear FKBP51 enhances the enzymatic activity of telomerase. The mitochondrial-nuclear trafficking is reversible, and certain situations such as viral infections promote the opposite trafficking, that is, FKBP51 abandons the nucleus and accumulates in mitochondria. In this article, we review the latest findings related to the mitochondrial-nuclear communication mediated by FKBP51 and speculate about the possible implications of this phenomenon.

Genetically engineered mouse models of FK506-binding protein 5

FK506 binding protein 51 (FKBP51) is a molecular chaperone that influences stress response. In addition to having an integral role in the regulation of steroid hormone receptors, including glucocorticoid receptor, FKBP51 has been linked with several biological processes including metabolism and neuronal health. Genetic and epigenetic alterations in the gene that encodes FKBP51, FKBP5, are associated with increased susceptibility to multiple neuropsychiatric disorders, which has fueled much of the research on this protein. Because of the complexity of these processes, animal models have been important in understanding the role of FKBP51. This review examines each of the current mouse models of FKBP5, which include whole animal knockout, conditional knockout, overexpression, and humanized mouse models. The generation of each model and observational details are discussed, including behavioral phenotypes, molecular changes, and electrophysiological alterations basally and following various challenges. While much has been learned through these models, there are still many aspects of FKBP51 biology that remain opaque and future studies are needed to help illuminate these current gaps in knowledge. Overall, FKBP5 continues to be an exciting potential target for stress-related disorders.

Functions of the Hsp90-Binding FKBP Immunophilins

The Hsp90 chaperone is known to interact with a diverse array of client proteins. However, in every case examined, Hsp90 is also accompanied by a single or several co-chaperone proteins. One class of co-chaperone contains a tetratricopeptide repeat (TPR) domain that targets the co-chaperone to the C-terminal region of Hsp90. Within this class are Hsp90-binding peptidylprolyl isomerases, most of which belong to the FK506-binding protein (FKBP) family. Despite the common association of FKBP co-chaperones with Hsp90, it is abundantly clear that the client protein influences, and is often influenced by, the particular FKBP bound to Hsp90. Examples include Xap2 in aryl hydrocarbon receptor complexes and FKBP52 in steroid receptor complexes. In this chapter, we discuss the known functional roles played by FKBP co-chaperones and, where possible, relate distinctive functions to structural differences between FKBP members.

Identification of candidate aberrant differentially methylated/expressed genes in asthma

BACKGROUND

Asthma is an important non-communicable disease worldwide. DNA methylation is associated with the occurrence and development of asthma. We are aimed at assuring differential expressed genes (DEGs) modified by aberrantly methylated genes (DMGs) and pathways related to asthma by integrating bioinformatics analysis.

METHODS

One mRNA dataset (GSE64913) and one gene methylation dataset (GSE137716) were selected from the Gene Expression Omnibus (GEO) database. Functional enrichment analysis was performed using GeneCodies 4.0 database. All gene expression matrices were analyzed by Gene set enrichment analysis (GSEA) software. STRING was applied to construct a protein-protein interaction (PPI) network to find the hub genes. Then, electronic validation was performed to verify the hub genes, followed by the evaluation of diagnostic value. Eventually, quantitative real-time polymerase chain reaction (qRT-PCR) was utilized to detect the expression of hub genes.

RESULTS

In total, 14 hypomethylated/high-expression genes and 10 hypermethylated/low-expression genes were obtained in asthma. Among them, 10 hub genes were identified in the PPI network. Functional analysis demonstrated that the differentially methylated/expressed genes were primarily associated with the lung development, cytosol and protein binding. Notably, HLA-DOA was enriched in asthma. FKBP5, WNT5A, TM4SF1, PDK4, EPAS1 and GMPR had potential diagnostic value for asthma.

CONCLUSION

The project explored the pathogenesis of asthma, which may provide a research basis for the prediction and the drug development of asthma.

FK506 binding protein 51: Its role in the adipose organ and beyond

There is a great body of evidence that the adipose organ plays a central role in the control not only of energy balance, but importantly, in the maintenance of metabolic homeostasis. Interest in the study of different aspects of its physiology grew in the last decades due to the pandemic of obesity and the consequences of metabolic syndrome. It was not until recently that the first evidence for the role of the high molecular weight immunophilin FK506 binding protein (FKBP) 51 in the process of adipocyte differentiation have been described. Since then, many new facets have been discovered of this stress-responsive FKBP51 as a central node for precise coordination of many cell functions, as shown for nuclear steroid receptors, autophagy, signaling pathways as Akt, p38 MAPK, and GSK3, as well as for insulin signaling and the control of glucose homeostasis. Thus, the aim of this review is to integrate and discuss the recent advances in the understanding of the many roles of FKBP51 in the adipose organ.

The Scaffold Immunophilin FKBP51 Is a Phosphoprotein That Undergoes Dynamic Mitochondrial-Nuclear Shuttling

The immunophilin FKBP51 forms heterocomplexes with molecular chaperones, protein-kinases, protein-phosphatases, autophagy-related factors, and transcription factors. Like most scaffold proteins, FKBP51 can use a simple tethering mechanism to favor the efficiency of interactions with partner molecules, but it can also exert more complex allosteric controls over client factors, the immunophilin itself being a putative regulation target. One of the simplest strategies for regulating pathways and subcellular localization of proteins is phosphorylation. In this study, it is shown that scaffold immunophilin FKBP51 is resolved by resolutive electrophoresis in various phosphorylated isoforms. This was evidenced by their reactivity with specific anti-phosphoamino acid antibodies and their fade-out by treatment with alkaline phosphatase. Interestingly, stress situations such as exposure to oxidants or in vivo fasting favors FKBP51 translocation from mitochondria to the nucleus. While fasting involves phosphothreonine residues, oxidative stress involves tyrosine residues. Molecular modeling predicts the existence of potential targets located at the FK1 domain of the immunophilin. Thus, oxidative stress favors FKBP51 dephosphorylation and protein degradation by the proteasome, whereas FK506 binding protects the persistence of the post-translational modification in tyrosine, leading to FKBP51 stability under oxidative conditions. Therefore, FKBP51 is revealed as a phosphoprotein that undergoes differential phosphorylations according to the stimulus.

FKBP4 regulates 5-fluorouracil sensitivity in colon cancer by controlling mitochondrial respiration

FKBP4 controls mitochondrial respiration via modulating COA6-mediated biogenesis and activity of mitochondrial complex IV, thereby regulating 5-fluorouracil sensitivity in colon cancer.

Mitochondrial respiration and metabolism play a key role in the pathogenesis and progression of colon adenocarcinoma (COAD). Here, we report a functional pool of FKBP4, a co-chaperone protein, in the mitochondrial intermembrane space (IMS) of colon cancer cells. We found that IMS-localized FKBP4 is essential for the maintenance of mitochondrial respiration, thus contributing to the sensitivity of COAD cells to 5-fluorouracil (5-FU). Mechanistically, FKBP4 interacts with COA6 and controls the assembly of the mitochondrial COA6/SCO1/SCO2 complex, thereby governing COA6-regulated biogenesis and activity of mitochondrial cytochrome c oxidase (complex IV). Thus, our data reveal IMS-localized FKBP4 as a novel regulator of 5-FU sensitivity in COAD, linking mitochondrial respiration to 5-FU sensitivity in COAD.

The emerging importance of immunophilins in fibrosis development

Immunophilins are a family of proteins encompassing FK506-binding proteins (FKBPs) and cyclophilins (Cyps). FKBPs and Cyps exert peptidyl-prolyl cis-trans isomerase (PPIase) activity, which facilitates diverse protein folding assembly, or disassembly. In addition, they bind to immunosuppressant medications where FKBPs bind to tacrolimus (FK506) and rapamycin, whereas cyclophilins bind to cyclosporin. Some large immunophilins have domains other than PPIase referred to as tetratricopeptide (TPR) domain, which is involved in heat shock protein 90 (Hsp90) and heat shock protein 70 (Hsp 70) chaperone interaction. The TPR domain confers immunophilins’ pleotropic actions to mediate various physiological and biochemical processes. So far, immunophilins have been implicated to play an important role in pathophysiology of inflammation, cancer and neurodegenerative disorders. However, their importance in the development of fibrosis has not yet been elucidated. In this review we focus on the pivotal functional and mechanistic roles of different immunophilins in fibrosis establishment affecting various organs. The vast majority of the studies reported that cyclophilin A, FKBP12 and FKBP10 likely induce organ fibrosis through the calcineurin or TGF-β pathways. FKBP51 demonstrated a role in myelofibrosis development through calcineurin-dependant pathway, STAT5 or NF-κB pathways. Inhibition of these specific immunophilins has been shown to decrease the extent of fibrosis suggesting that immunophilins could be a novel promising therapeutic target to prevent or reverse fibrosis.

Progesterone as an Anti-Inflammatory Drug and Immunomodulator: New Aspects in Hormonal Regulation of the Inflammation

The specific regulation of inflammatory processes by steroid hormones has been actively studied in recent years, especially by progesterone (P₄) and progestins. The mechanisms of the anti-inflammatory and immunomodulatory P₄ action are not fully clear. The anti-inflammatory effects of P₄ can be defined as nonspecific, associated with the inhibition of NF-κB and COX, as well as the inhibition of prostaglandin synthesis, or as specific, associated with the regulation of T-cell activation, the regulation of the production of pro- and anti-inflammatory cytokines, and the phenomenon of immune tolerance. The specific anti-inflammatory effects of P₄ and its derivatives (progestins) can also include the inhibition of proliferative signaling pathways and the antagonistic action against estrogen receptor beta-mediated signaling as a proinflammatory and mitogenic factor. The anti-inflammatory action of P₄ is accomplished through the participation of progesterone receptor (PR) chaperones HSP90, as well as immunophilins FKBP51 and FKBP52, which are the validated targets of clinically approved immunosuppressive drugs. The immunomodulatory and anti-inflammatory effects of HSP90 inhibitors, tacrolimus and cyclosporine, are manifested, among other factors, due to their participation in the formation of an active ligand–receptor complex of P₄ and their interaction with its constituent immunophilins. Pharmacological agents such as HSP90 inhibitors can restore the lost anti-inflammatory effect of glucocorticoids and P₄ in chronic inflammatory and autoimmune diseases. By regulating the activity of FKBP51 and FKBP52, it is possible to increase or decrease hormonal signaling, as well as restore it during the development of hormone resistance. The combined action of immunophilin suppressors with steroid hormones may be a promising strategy in the treatment of chronic inflammatory and autoimmune diseases, including endometriosis, stress-related disorders, rheumatoid arthritis, and miscarriages. Presumably, the hormone receptor- and immunophilin-targeted drugs may act synergistically, allowing for a lower dose of each.

Transcriptome Profile of Thyroid Glands in Bile Duct Ligation Mouse Model

Thyroid hormone (TH) contributes to multiple cellular mechanisms in the liver, muscle cells, adipose tissue, and brain, etc. In particular, the liver is an important organ in TH metabolism for the conversion of thyronine (T4) into triiodothyronine (T3) by the deiodinase enzyme. TH levels were significantly decreased and thyroid-stimulating hormone (TSH) levels were significantly increased in patients with liver failure compared with normal subjects. Among liver failure diseases, hepatic encephalopathy (HE) deserves more attention because liver damage and neuropathologies occur simultaneously. Although there is numerous evidence of TH dysregulation in the HE model, specific mechanisms and genetic features of the thyroid glands in the HE model are not fully understood. Here, we investigated the significantly different genes in the thyroid glands of a bile duct ligation (BDL) mouse model as the HE model, compared to the thyroid glands of the control mouse using RNA sequencing. We also confirmed the alteration in mRNA levels of thyroid gland function-related genes in the BDL mouse model. Furthermore, we evaluated the increased level of free T4 and TSH in the BDL mouse blood. Thus, we emphasize the potential roles of TH in liver metabolism and suggest that thyroid dysfunction-related genes in the HE model should be highlighted for finding the appropriate solution for an impaired thyroid system in HE.

FKBP51, AmotL2 and IQGAP1 Involvement in Cilastatin Prevention of Cisplatin-Induced Tubular Nephrotoxicity in Rats

The immunophilin FKBP51, the angiomotin AmotL2, and the scaffoldin IQGAP1 are overexpressed in many types of cancer, with the highest increase in leucocytes from patients undergoing oxaliplatin chemotherapy. Inflammation is involved in the pathogenesis of nephrotoxicity induced by platinum analogs. Cilastatin prevents renal damage caused by cisplatin. This functional and confocal microscopy study shows the renal focal-segmental expression of TNFα after cisplatin administration in rats, predominantly of tubular localization and mostly prevented by co-administration of cilastatin. FKBP51, AmotL2 and IQGAP1 protein expression increases slightly with cilastatin administration and to a much higher extent with cisplatin, in a cellular- and subcellular-specific manner. Kidney tubule cells expressing FKBP51 show either very low or no expression of TNFα, while cells expressing TNFα have low levels of FKBP51. AmotL2 and TNFα seem to colocalize and their expression is increased in tubular cells. IQGAP1 fluorescence increases with cilastatin, cisplatin and joint cilastatin-cisplatin treatment, and does not correlate with TNFα expression or localization. These data suggest a role for FKBP51, AmotL2 and IQGAP1 in cisplatin toxicity in kidney tubules and in the protective effect of cilastatin through inhibition of dehydropeptidase-I.

FKBP52 in Neuronal Signaling and Neurodegenerative Diseases: A Microtubule Story

The FK506-binding protein 52 (FKBP52) belongs to a large family of ubiquitously expressed and highly conserved proteins (FKBPs) that share an FKBP domain and possess Peptidyl-Prolyl Isomerase (PPIase) activity. PPIase activity catalyzes the isomerization of Peptidyl-Prolyl bonds and therefore influences target protein folding and function. FKBP52 is particularly abundant in the nervous system and is partially associated with the microtubule network in different cell types suggesting its implication in microtubule function. Various studies have focused on FKBP52, highlighting its importance in several neuronal microtubule-dependent signaling pathways and its possible implication in neurodegenerative diseases such as tauopathies (i.e., Alzheimer disease) and alpha-synucleinopathies (i.e., Parkinson disease). This review summarizes our current understanding of FKBP52 actions in the microtubule environment, its implication in neuronal signaling and function, its interactions with other members of the FKBPs family and its involvement in neurodegenerative disease.

Engagement of gcFKBP5/TRAF2 by spring viremia of carp virus to promote host cell apoptosis for supporting viral replication in grass carp

Spring viremia of carp virus (SVCV) causes severe morbidity and mortality in grass carp (Ctenopharyngodon idellus) in Europe, America and several Asian countries. We found that FKBP5 (FK506-binding protein 5) is an SVCV infection response factor; however, its role in the innate immune mechanism caused by SVCV infection remains unknown. This study cloned gcFKBP5 (grass carp FKBP5) and made its mimic protein structure for function discussion. We found that gcFKBP5 expression in the primary innate immune organs of grass carp, including intestine, liver and spleen, was highly upregulated by SVCV in 24 h, with a similar result in fish cells by poly(I:C) treatment. gcFKBP overexpression aggravates viral damage to cells and increases viral replication. Furthermore, SVCV engages gcFKBP5 interacting with TRAF2 (tumour necrosis factor receptor-associated factor 2) to promote host cell apoptosis for supporting viral replication. The enhanced viral replication seems not to be due to the repression of IFN and other antiviral factors as expected. For the first time, these data show the pivotal role of gcFKBP5 in the innate immune response of grass carp to SVCV infection.

AmotL2, IQGAP1, and FKBP51 Scaffold Proteins in Glioblastoma Stem Cell Niches

Glioma stem cells (GSCs) live in a continuous process of stemness reprogramming to achieve specific cell commitment within the so-called GSC niches, specifically located in periarteriolar regions. In this review, we analyze the expression levels, cellular and subcellular location, and role of three scaffold proteins (IQGAP1, FKBP51, and AmotL2) in GSC niches. Scaffold proteins contribute to cell differentiation, migration, and angiogenesis in glioblastoma. It could be of diagnostic interest for establishing stages, for therapeutic targets, and for improving glioblastoma prognosis, which is still at the experimental level.

FKBP51 and the molecular chaperoning of metabolism

The molecular chaperone FK506-binding protein 51 (FKBP51) is gaining attention as a meaningful biomarker of metabolic dysfunction. This review examines the emerging contributions of FKBP51 in adipogenesis and lipid metabolism, myogenesis and protein catabolism, and glucocorticoid-induced skin hypoplasia and dermal adipocytes. The FKBP51 signaling mechanisms that may explain these metabolic consequences are discussed. These mechanisms are diverse, with FKBP51 independently and directly regulating phosphorylation cascades and nuclear receptors. We provide a discussion of the newly developed compounds that antagonize FKBP51, which may offer therapeutic advantages for adiposity. These observations suggest we are only beginning to uncover the complex nature of FKBP51 and its molecular chaperoning of metabolism.

Corticosteroid receptors as a model for the Hsp90•immunophilin-based transport machinery

Steroid receptors form soluble heterocomplexes with the 90-kDa heat-shock protein (Hsp90) and other chaperones and co-chaperones. The assembly and composition of the oligomer is influenced by the presence and nature of the bound steroid. Although these receptors shuttle dynamically in and out of the nucleus, their primary localization in the absence of steroid can be mainly cytoplasmic, mainly nuclear, or partitioned into both cellular compartments. Upon steroid binding, receptors become localized to the nucleus via the transportosome, a retrotransport molecular machinery that comprises Hsp90, a high-molecular-weight immunophilin, and dynein motors. This molecular machinery, first evidenced in steroid receptors, can also be used by other soluble proteins. In this review, we dissect the complete model of this transport machinery system.

Di(isononyl) cyclohexane-1,2-dicarboxylate (DINCH) alters transcriptional profiles, lipid metabolism and behavior in zebrafish larvae

Plasticizers are commonly used in different consumer goods and personal care products to provide flexibility, durability and elasticity to polymers. Due to their reported toxicity, the use of several plasticizers, including phthalates has been regulated and/or banned from the market. Di(isononyl) cyclohexane-1,2-dicarboxylate (DINCH) is an alternative plasticizer that was introduced to replace toxic plasticizers. Increasing global demand and lack of toxicity data and safety assessment of DINCH have raised the concern to human and animal health. Hence, in the present study, we investigated the adverse effects of DINCH (at concentrations ranging from 0.01 to 10 μM) in early developmental stages of zebrafish using different endpoints such as hatching rate, developmental abnormalities, lipid content, behavior analysis and gene expression. We found that DINCH caused hatching delay in a dose-dependent manner and altered the expression of genes involved in stress response. Lipid staining using Oil Red O stain showed a slight lipid accumulation around the yolk, brain, eye and neck with increasing concentration. Genes associated with lipid transport such as fatty acid synthesis, β-oxidation, elongation, lipid transport were significantly altered by DINCH. Genes involved in cholesterol biosynthesis and homeostasis were also affected by DINCH indicating possible developmental neurotoxicity. Behavioral analysis of larvae demonstrated a distinct locomotor activity upon exposure to DINCH. The present data shows that DINCH could induce physiological and metabolic toxicity to aquatic organisms. Hence, further analyses and environmental monitoring of DINCH should be conducted to determine its safety and toxicity levels.

Mitochondrial Glucocorticoid Receptors and Their Actions

Mitochondria are membrane organelles present in almost all eukaryotic cells. In addition to their well-known role in energy production, mitochondria regulate central cellular processes, including calcium homeostasis, Reactive Oxygen Species (ROS) generation, cell death, thermogenesis, and biosynthesis of lipids, nucleic acids, and steroid hormones. Glucocorticoids (GCs) regulate the mitochondrially encoded oxidative phosphorylation gene expression and mitochondrial energy metabolism. The identification of Glucocorticoid Response Elements (GREs) in mitochondrial sequences and the detection of Glucocorticoid Receptor (GR) in mitochondria of different cell types gave support to hypothesis that mitochondrial GR directly regulates mitochondrial gene expression. Numerous studies have revealed changes in mitochondrial gene expression alongside with GR import/export in mitochondria, confirming the direct effects of GCs on mitochondrial genome. Further evidence has made clear that mitochondrial GR is involved in mitochondrial function and apoptosis-mediated processes, through interacting or altering the distribution of Bcl2 family members. Even though its exact translocation mechanisms remain unknown, data have shown that GR chaperones (Hsp70/90, Bag-1, FKBP51), the anti-apoptotic protein Bcl-2, the HDAC6- mediated deacetylation and the outer mitochondrial translocation complexes (Tom complexes) co-ordinate GR mitochondrial trafficking. A role of mitochondrial GR in stress and depression as well as in lung and hepatic inflammation has also been demonstrated.

FK506-binding protein 5 promotes the progression of papillary thyroid carcinoma

Objective

To detect the expression of FK506-binding protein 5 (FKBP5) in human papillary thyroid carcinoma (PTC) tissues, and explore its possible role in the progression of PTC.

Methods

FKBP5 expression levels were assessed in 115 PTC tissues and corresponding normal tissues by immunohistochemistry. We also examined the correlations between FKBP5 expression and clinicopathological factors and survival in 75 patients with PTC. The effects of FKBP5 on the proliferation and apoptosis of PTC cells were detected by colony-formation, MTT, and flow cytometry assays, respectively. We further investigated the effects of FKBP5 on tumor growth in mice.

Results

We revealed high expression levels of FKBP5 in human PTC tissues compared with normal tissues. Furthermore, high FKBP5 expression was associated with an increased incidence of intraglandular dissemination, and lower overall and progression-free survival. FKBP5 depletion remarkably suppressed the proliferation and induced apoptosis of PTC cells in vitro. FKBP5 further contributed to the growth of PTC tumors in mice.

Conclusions

The results of this study demonstrated the potential involvement of FKBP5 in the progression of PTC, and confirmed FKBP5 as a novel therapeutic target for PTC treatment.

Cyclophilin A is a mitochondrial factor that forms complexes with p23 - correlative evidence for an anti-apoptotic action

Cyclophilin A (CyPA, also known as PPIA) is an abundant and ubiquitously expressed protein belonging to the immunophilin family, which has intrinsic peptidyl-prolyl-(cis/trans)-isomerase enzymatic activity. CyPA mediates immunosuppressive action of the cyclic undecapeptide cyclosporine A and is also involved in multiple cellular processes, such as protein folding, intracellular trafficking, signal transduction and transcriptional regulation. CyPA is abundantly expressed in cancer cells, and, owing to its chaperone nature, its expression is induced upon the onset of stress. In this study, we demonstrated that a significant pool of this immunophilin is primarily an intramitochondrial factor that migrates to the nucleus when cells are stimulated with stressors. CyPA shows anti-apoptotic action per se and the capability of forming ternary complexes with cytochrome c and the small acidic co-chaperone p23, the latter interaction being independent of the usual association of p23 with the heat-shock protein of 90 kDa, Hsp90. These CyPA•p23 complexes enhance the anti-apoptotic response of the cell, suggesting that both proteins form a functional unit, the high level of expression of which plays a significant role in cell survival.

The glucocorticoid receptor-FKBP51 complex contributes to fear conditioning and posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) can develop after exposure to severe psychological trauma, leaving patients with disabling anxiety, nightmares, and flashbacks. Current treatments are only partially effective, and development of better treatments is hampered by limited knowledge of molecular mechanisms underlying PTSD. We have discovered that the glucocorticoid receptor (GR) and FK506 binding protein 51 (FKBP51) form a protein complex that is elevated in PTSD patients compared with unaffected control subjects, subjects exposed to trauma without PTSD, and patients with major depressive disorder (MDD). The GR-FKBP51 complex is also elevated in fear-conditioned mice, an aversive learning paradigm that models some aspects of PTSD. Both PTSD patients and fear-conditioned mice had decreased GR phosphorylation, decreased nuclear GR, and lower expression of 14-3-3ε, a gene regulated by GR. We created a peptide that disrupts GR-FKBP51 binding and reverses behavioral and molecular changes induced by fear conditioning. This peptide reduces freezing time and increases GR phosphorylation, GR-FKBP52 binding, GR nuclear translocation, and 14-3-3ε expression in fear-conditioned mice. These experiments demonstrate a molecular mechanism contributing to PTSD and suggest that the GR-FKBP51 complex may be a diagnostic biomarker and a potential therapeutic target for preventing or treating PTSD.

Nucleocytoplasmic shuttling of the glucocorticoid receptor is influenced by tetratricopeptide repeat-containing proteins

It has been demonstrated that tetratricopeptide-repeat (TPR) domain proteins regulate the subcellular localization of glucocorticoid receptor (GR). This study analyses the influence of the TPR domain of high molecular weight immunophilins in the retrograde transport and nuclear retention of GR. Overexpression of the TPR peptide prevented efficient nuclear accumulation of the GR by disrupting the formation of complexes with the dynein-associated immunophilin FKBP52 (also known as FKBP4), the adaptor transporter importin-β1 (KPNB1), the nuclear pore-associated glycoprotein Nup62 and nuclear matrix-associated structures. We also show that nuclear import of GR was impaired, whereas GR nuclear export was enhanced. Interestingly, the CRM1 (exportin-1) inhibitor leptomycin-B abolished the effects of TPR peptide overexpression, although the drug did not inhibit GR nuclear export itself. This indicates the existence of a TPR-domain-dependent mechanism for the export of nuclear proteins. The expression balance of those TPR domain proteins bound to the GR-Hsp90 complex may determine the subcellular localization and nucleocytoplasmic properties of the receptor, and thereby its pleiotropic biological properties in different tissues and cell types.

Post-translational modifications and stress adaptation: the paradigm of FKBP51

Adaptation to stress is a fundamental requirement to cope with changing environmental conditions that pose a threat to the homeostasis of cells and organisms. Post-translational modifications (PTMs) of proteins represent a possibility to quickly produce proteins with new features demanding relatively little cellular resources. FK506 binding protein (FKBP) 51 is a pivotal stress protein that is involved in the regulation of several executers of PTMs. This mini-review discusses the role of FKBP51 in the function of proteins responsible for setting the phosphorylation, ubiquitination and lipidation of other proteins. Examples include the kinases Akt1, CDK5 and GSK3β, the phosphatases calcineurin, PP2A and PHLPP, and the ubiquitin E3-ligase SKP2. The impact of FKBP51 on PTMs of signal transduction proteins significantly extends the functional versatility of this protein. As a stress-induced protein, FKBP51 uses re-setting of PTMs to relay the effect of stress on various signaling pathways.

Regulation of FKBP51 and FKBP52 functions by post-translational modifications

FKBP51 and FKBP52 are two iconic members of the family of peptidyl-prolyl-(cis/trans)-isomerases (EC: 5.2.1.8), which comprises proteins that catalyze the cis/trans isomerization of peptidyl-prolyl peptide bonds in unfolded and partially folded polypeptide chains and native state proteins. Originally, both proteins have been studied as molecular chaperones belonging to the steroid receptor heterocomplex, where they were first discovered. In addition to their expected role in receptor folding and chaperoning, FKBP51 and FKBP52 are also involved in many biological processes, such as signal transduction, transcriptional regulation, protein transport, cancer development, and cell differentiation, just to mention a few examples. Recent studies have revealed that both proteins are subject of post-translational modifications such as phosphorylation, SUMOlyation, and acetylation. In this work, we summarize recent advances in the study of these immunophilins portraying them as scaffolding proteins capable to organize protein heterocomplexes, describing some of their antagonistic properties in the physiology of the cell, and the putative regulation of their properties by those post-translational modifications.

Restoration of FKBP51 protein promotes the progression of castration resistant prostate cancer

Background

As deregulation of androgen receptor (AR) signaling target genes is associated with tumorigenesis and the development of prostate cancer (PCa), AR signaling is the primary therapeutic target for PCa. Although patients initially responses to first-line androgen deprivation therapies (ADTs), most of them with advanced PCa progress to lethal castration-resistant prostate cancer (CRPC). Recent studies have suggested the molecular mechanisms by which AR elicit the robust up-regulation of the FKBP51 gene. We suggest that restored expression of FKBP51 gene, modulated by androgen receptor splicing variant 7 (AR-V7) which replaces full length androgen receptor (AR-FL) in androgen ablation status, promotes CRPC progression through activating NF-κB signaling.

Methods

Immunohistochemistry assays were used to detect the expression of AR-V7, FKBP51 and NF-κB signaling correlated proteins in CRPC tissues. An androgen ablation resistant PCa cell line model established by Long-term culturing in androgen depleted medium, named androgen-independent LNCaP (LNCaP-AI) cells, were used to dynamically monitor FKBP51 expression during the process of androgen dependent PCa cells transforming into androgen-independent cells, as well as its association with NF-κB signal pathway. LNCaP-AI cell line was determined to express AR-V7 protein continuously. Luciferase reporter assays and DNA pull down were used to determine the association between AR-V7 and FKBP51.

Results

Our results suggested that CRPC patients with AR-V7 high expression tend to have higher expression of FKBP51 and enhanced NF-κB signaling compared with AR-V7 negative patients. Knockdown of AR-V7 or FKBP51 in LNCaP-AI cells attenuated the level of p-NF-κB (Ser536) and androgen-resistant cells growth. Luciferase reporter assays and DNA pull down results indicated that FKBP51 was transcriptionally promoted by AR-V7 in absence of androgen, which enhanced NF-κB signaling.

Conclusions

Because of upregulation of AR-V7 in androgen-independent PCa cells, increasing of FKBP51 induced NF-κB signaling, leading to progression of CRPC.

Broad-spectrum antitumor properties of Withaferin A: a proteomic perspective

The multifunctional antitumor properties of Withaferin A (WA), the manifold studied bioactive compound of the plant Withania somnifera, have been well established in many different in vitro and in vivo cancer models. This undoubtedly has led to a much better insight in the underlying mechanisms of WAs broad antitumor activity range, but also raises additional challenging questions on how all these antitumor properties could be explained on a molecular level. Therefore, a lot of effort was made to characterize the cellular WA target proteins, since these binding events will lead and initiate the observed downstream effects. Based on a proteomic perspective, this review provides novel insights in the molecular chain of events by which WA potentially exercises its antitumor activities. We illustrate that WA triggers multiple cellular stress pathways such as the NRF2-mediated oxidative stress response, the heat shock response and protein translation events and at the same time inhibits these cellular protection mechanisms, driving stressed cancer cells towards a fatal state of collapse. If cancer cells manage to restore homeostasis and survive, a stress-independent WA antitumor response comes into play. These include the known inhibition of cytoskeleton proteins, NFκB pathway inhibition and cell cycle inhibition, among others. This review therefore provides a comprehensive overview which integrates the numerous WA-protein binding partners to formulate a general WA antitumor mechanism.

HIV in the cART era and the mitochondrial: immune interface in the CNS

HIV-associated neurocognitive disorders (HAND) persist in the era of effective combined antiretroviral therapy (cART). A large body of literature suggests that mitochondrial dysfunction is a prospective etiology of HAND in the cART era. While viral load is often suppressed and the immune system remains intact in HIV+ patients on cART, evidence suggests that the central nervous system (CNS) acts as a reservoir for virus and low-level expression of viral proteins, which interact with mitochondria. In particular, the HIV proteins glycoprotein 120, transactivator of transcription, viral protein R, and negative factor have each been linked to mitochondrial dysfunction in the brain. Moreover, cART drugs have also been shown to have detrimental effects on mitochondrial function. Here, we review the evidence generated from human studies, animal models, and in vitro models that support a role for HIV proteins and/or cART drugs in altered production of adenosine triphosphate, mitochondrial dynamics, mitophagy, calcium signaling and apoptosis, oxidative stress, mitochondrial biogenesis, and immunometabolism in the CNS. When insightful, evidence of HIV or cART-induced mitochondrial dysfunction in the peripheral nervous system or other cell types is discussed. Lastly, therapeutic approaches to targeting mitochondrial dysfunction have been summarized with the aim of guiding new investigations and providing hope that mitochondrial-based drugs may provide relief for those suffering with HAND.

Higd1a Protects Cells from Lipotoxicity under High-Fat Exposure

Hypoxia-inducible gene domain family member 1A (Higd1a) has recently been reported to protect cells from hypoxia by helping to maintain normal mitochondrial function. The potential induction of Higd1a under high-fat exposure and whether it could protect cells from oxidative stress attracted our attention. Initially, 0.4 mM oleic acid and 0.2 mM palmitate were added to the growth media of HepG2 and LO2 cells for 72 hours. We discovered increased Higd1a expression, and knocking down Higd1a impaired mitochondrial transmembrane potential and induced cell apoptosis. We then identified that elevated reactive oxygen species (ROS) is responsible for increased Higd1a expression. Furthermore, we found that ROS promoted Higd1a expression by upregulating HIF-1a and PGC-1a expressions, and these two proteins could exert synergistic effects in inducing Higd1a expression. Taken together, these data suggest that Higd1a plays positive roles in protecting cells from oxidative stress, and ROS could induce Higd1a expression by upregulating PGC-1a and HIF-1a expressions.

IQGAP1, AmotL2, and FKBP51 Scaffoldins in the Glioblastoma Microenvironment

Glioblastoma (GB) is the most frequently occurring and aggressive primary brain tumor. Glioma stem cells (GSCs) and astrocytoma cells are the predominant malignant cells occurring in GB besides a highly heterogeneous population of migrating, neovascularizing and infiltrating myeloid cells that forms a complex tumor microenvironment (TME). Cross talk between the TME cells is pivotal in the biology of this tumor and, consequently, adaptor proteins at critical junctions of signaling pathways may be crucial. Scaffold proteins (scaffolins or scaffoldins) integrate external and internal stimuli to regulate various signaling pathways, interacting simultaneously with multiple proteins involved. We investigated by double and triple immunofluorescence the localization of IQGAP1, AmotL2, and FKBP51, three closely related scaffoldins, in malignant cells and TME of human GB tumors. We found that IQGAP1 is preferentially expressed in astrocytoma cells, AmotL2 in GSCs, and FKBP51 in white blood cells in human GB tumors. As GSCs are specially the target for novel therapies, we will investigate in further studies whether AmotL2 inhibition is effective in the treatment of GB.

Proteome profiling of triple negative breast cancer cells overexpressing NOD1 and NOD2 receptors unveils molecular signatures of malignant cell proliferation

Background

Triple negative breast cancer (TNBC) is a malignancy with very poor prognosis, due to its aggressive clinical characteristics and lack of response to receptor-targeted drug therapy. In TNBC, immune-related pathways are typically upregulated and may be associated with a better prognosis of the disease, encouraging the pursuit for immunotherapeutic options. A number of immune-related molecules have already been associated to the onset and progression of breast cancer, including NOD1 and NOD2, innate immune receptors of bacterial-derived components which activate pro-inflammatory and survival pathways. In the context of TNBC, overexpression of either NOD1or NOD2 is shown to reduce cell proliferation and increase clonogenic potential in vitro. To further investigate the pathways linking NOD1 and NOD2 signaling to tumorigenesis in TNBC, we undertook a global proteome profiling of TNBC-derived cells ectopically expressing each one of these NOD receptors.

Results

We have identified a total of 95 and 58 differentially regulated proteins in NOD1- and NOD2-overexpressing cells, respectively. We used bioinformatics analyses to identify enriched molecular signatures aiming to integrate the differentially regulated proteins into functional networks. These analyses suggest that overexpression of both NOD1 and NOD2 may disrupt immune-related pathways, particularly NF-κB and MAPK signaling cascades. Moreover, overexpression of either of these receptors may affect several stress response and protein degradation systems, such as autophagy and the ubiquitin-proteasome complex. Interestingly, the levels of several proteins associated to cellular adhesion and migration were also affected in these NOD-overexpressing cells.

Conclusions

Our proteomic analyses shed new light on the molecular pathways that may be modulating tumorigenesis via NOD1 and NOD2 signaling in TNBC. Up- and downregulation of several proteins associated to inflammation and stress response pathways may promote activation of protein degradation systems, as well as modulate cell-cycle and cellular adhesion proteins. Altogether, these signals seem to be modulating cellular proliferation and migration via NF-κB, PI3K/Akt/mTOR and MAPK signaling pathways. Further investigation of altered proteins in these pathways may provide more insights on relevant targets, possibly enabling the immunomodulation of tumorigenesis in the aggressive TNBC phenotype.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5523-6) contains supplementary material, which is available to authorized users.

Compression of Large Sets of Sequence Data Reveals Fine Diversification of Functional Profiles in Multigene Families of Proteins: A Study for Peptidyl-Prolyl cis/trans Isomerases (PPIase)

In this technical note, we describe analyses of more than 15,000 sequences of FK506-binding proteins (FKBP) and cyclophilins, also known as peptidyl-prolyl cis/trans isomerases (PPIases). We have developed a novel way of displaying relative changes of amino acid (AA)-residues at a given sequence position by using heat-maps. This type of representation allows simultaneous estimation of conservation level in a given sequence position in the entire group of functionally-related paralogues (multigene family of proteins). We have also proposed that at least two FKBPs, namely FKBP36, encoded by the Fkbp6 gene and FKBP51, encoded by the Fkbp5 gene, can form dimers bound via a disulfide bridge in the nucleus. This type of dimer may have some crucial function in the regulation of some nuclear complexes at different stages of the cell cycle.

Biological Actions of the Hsp90-binding Immunophilins FKBP51 and FKBP52

Immunophilins are a family of proteins whose signature domain is the peptidylprolyl-isomerase domain. High molecular weight immunophilins are characterized by the additional presence of tetratricopeptide-repeats (TPR) through which they bind to the 90-kDa heat-shock protein (Hsp90), and via this chaperone, immunophilins contribute to the regulation of the biological functions of several client-proteins. Among these Hsp90-binding immunophilins, there are two highly homologous members named FKBP51 and FKBP52 (FK506-binding protein of 51-kDa and 52-kDa, respectively) that were first characterized as components of the Hsp90-based heterocomplex associated to steroid receptors. Afterwards, they emerged as likely contributors to a variety of other hormone-dependent diseases, stress-related pathologies, psychiatric disorders, cancer, and other syndromes characterized by misfolded proteins. The differential biological actions of these immunophilins have been assigned to the structurally similar, but functionally divergent enzymatic domain. Nonetheless, they also require the complementary input of the TPR domain, most likely due to their dependence with the association to Hsp90 as a functional unit. FKBP51 and FKBP52 regulate a variety of biological processes such as steroid receptor action, transcriptional activity, protein conformation, protein trafficking, cell differentiation, apoptosis, cancer progression, telomerase activity, cytoskeleton architecture, etc. In this article we discuss the biology of these events and some mechanistic aspects.

Hsp90 Heterocomplexes Regulate Steroid Hormone Receptors: From Stress Response to Psychiatric Disease

The hypothalamus-pituitary-adrenal (HPA) axis directly controls the stress response. Dysregulation of this neuroendocrine system is a common feature among psychiatric disorders. Steroid hormone receptors, like glucocorticoid receptor (GR), function as transcription factors of a diverse set of genes upon activation. This activity is regulated by molecular chaperone heterocomplexes. Much is known about the structure and function of these GR/heterocomplexes. There is strong evidence suggesting altered regulation of steroid receptor hormones by chaperones, particularly the 51 kDa FK506-binding protein (FKBP51), may work with environmental factors to increase susceptibility to various psychiatric illnesses including post-traumatic stress disorder (PTSD), major depressive disorder (MDD), and anxiety. This review highlights the regulation of steroid receptor dynamics by the 90kDa heat shock protein (Hsp90)/cochaperone heterocomplexes with an in depth look at how the structural regulation and imbalances in cochaperones can cause functional effects on GR activity. Links between the stress response and circadian systems and the development of novel chaperone-targeting therapeutics are also discussed.

Understanding the Molecular Mechanisms Underpinning Gene by Environment Interactions in Psychiatric Disorders: The FKBP5 Model

Epidemiologic and genetic studies suggest common environmental and genetic risk factors for a number of psychiatric disorders, including depression, bipolar disorder, and schizophrenia. Genetic and environmental factors, especially adverse life events, not only have main effects on disease development but also may interact to shape risk and resilience. Such gene by adversity interactions have been described for FKBP5, an endogenous regulator of the stress-neuroendocrine system, conferring risk for a number of psychiatric disorders. In this review, we present a molecular and cellular model of the consequences of FKBP5 by early adversity interactions. We illustrate how altered genetic and epigenetic regulation of FKBP5 may contribute to disease risk by covering evidence from clinical and preclinical studies of FKBP5 dysregulation, known cell-type and tissue-type expression patterns of FKBP5 in humans and animals, and the role of FKBP5 as a stress-responsive molecular hub modulating many cellular pathways. FKBP5 presents the possibility to better understand the molecular and cellular factors contributing to a disease-relevant gene by environment interaction, with implications for the development of biomarkers and interventions for psychiatric disorders.

Antenatal pomegranate juice rescues hypoxia-induced fetal growth restriction in pregnant mice while reducing placental cell stress and apoptosis

INTRODUCTION

There is a need for prophylaxis to reduce placental-associated intrauterine growth restriction (IUGR). Pomegranate juice (PJ) is replete with phytochemicals having biological effects at non-pharmacological concentrations. We test the hypothesis that exposure of pregnant mice to hypoxia late in gestation induces cellular stress in the placenta, which can be ameliorated by antecedent maternal consumption of PJ.

MATERIALS AND METHODS

We exposed pregnant mice to 12% or 21% oxygen, with food ad libitum or restricted, and with consumption of PJ or glucose between 12.5 and 18.5 days post conception (dpc). We examined the outcomes of the nine groups (n = 10) at 18.5 dpc, quantifying fetal and placental weights and placental labyrinthine and junctional zone depths and areas. We assayed cellular stress by expression of Hsp90 and apoptosis by TUNEL staining and expression of cleaved caspase 3.

RESULTS

Maternal exposure to 12% oxygen or food restriction in 21% oxygen, induced IUGR, compared to control. The labyrinth to junctional zone ratio was lower in hypoxic ad libitum, compared to normoxic food-restricted, placentas. Antenatal PJ prior to and during hypoxic exposure significantly improved fetal growth, reduced Hsp90 expression, and limited apoptosis in the labyrinth, while enhancing junctional zone apoptosis.

DISCUSSION

Maternal exposure to hypoxia induces IUGR, cell stress, and apoptosis in mouse placentas. The labyrinth and junctional zone of the mouse placenta are differentially sensitive to FiO₂ and to PJ. PJ offers benefits in the prophylaxis of IUGR in the mouse, but PJ effects on the junctional zone require further study.

Inhibition of heat shock protein 90 improves pulmonary arteriole remodeling in pulmonary arterial hypertension

While the molecular chaperone heat shock protein 90 (HSP90) is involved in a multitude of physiological and pathological processes, its role relating to pulmonary arterial hypertension (PAH) remains unclear. In the present study, we investigated the effect in which HSP90 improves pulmonary arteriole remodeling, and explored the therapeutic utility of targeting HSP90 as therapeutic drug for PAH. By Elisa and immunohistochemistry, HSP90 was found to be increased in both plasma and membrane walls of pulmonary arterioles from PAH patients. Moreover, plasma HSP90 levels positively correlated with mean pulmonary arterial pressure and C-reactive protein. In a monocrotaline-induced rat model of PH, we found that 17-AAG, a HSP90-inhibitor, alleviated the progress of PH, demonstrated by lower pulmonary arterial pressure and absence of right ventricular hypertrophy. Immunohistochemical staining demonstrated that 17-AAG improved pulmonary arteriole remodeling on the basis of reduced wall thickness and wall area. The inflammatory response attributed to PH could be attenuated by 17-AAG through reduction of NF-κB signaling. Moreover, 17-AAG was found to suppress PDGF-stimulated proliferation and migration of pulmonary artery smooth muscle cells (PASMCs) through induction of cell cycle arrest in the G1 phase. In conclusion, HSP90 inhibitor 17-AAG could improve pulmonary arteriole remodeling via inhibiting the excessive proliferation of PASMCs, and inhibition of HSP90 may represent a therapeutic avenue for the treatment of PAH.