FKBP52 in Neuronal Signaling and Neurodegenerative Diseases: A Microtubule Story

Assessment of prognosis and responsiveness to immunotherapy in colorectal cancer patients based on the level of immune cell infiltration

Objective

To build a new prognostic risk assessment model based on immune cell co-expression networks for predicting overall survival and evaluating the efficacy of immunotherapy for colon cancer patients.

Methods

The Cancer Genome Atlas (TCGA) database was used to obtain mRNA expression profiling data, clinical information, and somatic mutation data from colorectal cancer patients. The degree of tumor immune cell infiltration of the samples was analyzed using the CIBERSORT algorithm. Co-expression of immune-related genes was analyzed using weighted correlation network analysis (WGCNA) and gene modules were identified. Prognosis-related genes were screened and models were constructed using LASSO-Cox analysis. The models were validated by survival analysis. The prognostic potential of the models was quantitatively assessed using Cox regression analysis and the development of column line plots. Immunotherapy sensitivity analysis was performed using CIBERSORT and TIMER algorithms. Gene biofunction analysis was performed using Gene set enrichment analysis (GSEA) and Gene set variation analysis (GSVA). And the chemotherapeutic response to different drugs was assessed.

Results

We established a novel prognostic model utilizing the WGCNA method, which demonstrated robust predictive accuracy for patient survival. The high-risk subgroup in our model exhibited elevated immune cell infiltration coupled with a higher tumor mutation burden, but the difference in response to immunotherapy was not significant compared to the low-risk group. Furthermore, we identified distinct chemotherapy responses to 39 drugs between these risk subgroups.

Conclusion

This study revealed a significant correlation between high levels of immune infiltration and unfavorable prognosis in patients with colon cancer. Furthermore, an accurate prognostic risk prediction model based on the co-expression of relevant genes by immune cells was developed, enabling precise prediction of survival of colon cancer patients. These findings offer valuable insights for accurate prognostication and comprehensive management of individuals diagnosed with colon cancer.

Interplay of p23 with FKBP51 and their chaperone complex in regulating tau aggregation

The pathological deposition of tau and amyloid-beta into insoluble amyloid fibrils are pathological hallmarks of Alzheimer's disease. Molecular chaperones are important cellular factors contributing to the regulation of tau misfolding and aggregation. Here we reveal an Hsp90-independent mechanism by which the co-chaperone p23 as well as a molecular complex formed by two co-chaperones, p23 and FKBP51, modulates tau aggregation. Integrating NMR spectroscopy, SAXS, molecular docking, and site-directed mutagenesis we reveal the structural basis of the p23-FKBP51 complex. We show that p23 specifically recognizes the TPR domain of FKBP51 and interacts with tau through its C-terminal disordered tail. We further show that the p23-FKBP51 complex binds tau to form a dynamic p23-FKBP51-tau trimeric complex that delays tau aggregation and thus may counteract Hsp90-FKBP51 mediated toxicity. Taken together, our findings reveal a co-chaperone mediated Hsp90-independent chaperoning of tau protein.

Self-Healing COCu-Tac Hydrogel Enhances iNSCs Transplantation for Spinal Cord Injury by Promoting Mitophagy via the FKBP52/AKT Pathway

In the realm of neural regeneration post-spinal cord injury, hydrogel scaffolds carrying induced neural stem cells (iNSCs) have demonstrated significant potential. However, challenges such as graft rejection and dysfunction caused by mitochondrial damage persist after transplantation, presenting formidable barriers. Tacrolimus, known for its dual role as an immunosuppressant and promoter of neural regeneration, holds the potential for enhancing iNSC transplantation. However, systemic administration of tacrolimus often comes with severe side effects. This study pioneers the development of a self-healing hydrogel with sustained-release tacrolimus (COCu-Tac), tailored specifically for iNSC transplantation after spinal cord injury. This research reveals that the sustained release of tacrolimus enhances axonal growth and improves mitochondrial quality control in iNSCs and neurons. Further analysis shows that tacrolimus targets FKBP52 rather than FKBP51, enhancing mitophagy via the FKBP52/AKT pathway. This advanced system demonstrates significant efficacy in promoting neural regeneration and restoring motor function following spinal cord injury.

Structure and function of the TPR-domain immunophilins FKBP51 and FKBP52 in normal physiology and disease

Coordinated cochaperone interactions with Hsp90 and associated client proteins are crucial for a multitude of signaling pathways in normal physiology, as well as in disease settings. Research on the molecular mechanisms regulated by the Hsp90 multiprotein complexes has demonstrated increasingly diverse roles for cochaperones throughout Hsp90-regulated signaling pathways. Thus, the Hsp90-associated cochaperones have emerged as attractive therapeutic targets in a wide variety of disease settings. The tetratricopeptide repeat (TPR)-domain immunophilins FKBP51 and FKBP52 are of special interest among the Hsp90-associated cochaperones given their Hsp90 client protein specificity, ubiquitous expression across tissues, and their increasingly important roles in neuronal signaling, intracellular calcium release, peptide bond isomerization, viral replication, steroid hormone receptor function, and cell proliferation to name a few. This review summarizes the current knowledge of the structure and molecular functions of TPR-domain immunophilins FKBP51 and FKBP52, recent findings implicating these immunophilins in disease, and the therapeutic potential of targeting FKBP51 and FKBP52 for the treatment of disease.

FKBP4 promotes glycolysis and hepatocellular carcinoma progression via p53/HK2 axis

FKBP4, a member of the FK506-binding protein (FKBP) family, is a promising target for a variety of disorders, including cancer. However, its underlying molecular mechanism and potential function in hepatocellular carcinoma (HCC) are largely elusive. Therefore, we aimed to investigate the expression status, functional implications and underlying mechanisms of FKBP4 in HCC. Our bioinformatics analysis of TCGA LIHC datasets, ICGC LIRI-JP datasets and GEO datasets results showed FKBP4 was upregulated in HCC tissues. We also confirmed the elevated FKBP4 in clinical HCC samples. Additionally, quantitative RT-PCR results revealed FKBP4 was highly expressed in all five tested HCC cell lines. We also observed a correlation between elevated FKBP4 expression and poor prognosis in HCC patients. Loss of FKBP4 can inhibit the proliferation and migration in HCC cells. Furthermore, we found that silencing FKBP4 suppressed glucose uptake, lactic acid production and 18F-FDG uptake compared with the control group. Mechanistically, our funding indicated that FKBP4 participates in glycolysis through p53 mediated HK2 signaling pathway, specially, FKBP4 knockdown promotes the expression and stability of p53 protein rather than affecting the transcription level. Finally, rescue experiments revealed that simultaneous knockdown of both FKBP4 and p53 partially reversed the inhibitory effects on HK2 protein levels and 18F-FDG uptake. Our study elucidates a novel role of FKBP4 in promoting HCC development and glycolysis by modulating the p53/HK2 signaling pathway. Given the critical role of aerobic glycolysis in the progression of HCC, targeting FKBP4 may offer a new therapeutic strategy for treating this malignancy.

Molecular Insights into Tau Pathology and its Therapeutic Strategies in Alzheimer's Disease

Alzheimer's disease (AD) is the most common cause of dementia. The two major hallmarks of this disease are extracellular amyloid plaques and intracellular neurofibrillary tangles in the brain, accompanied by loss of neurons and synapses. The plaques and tangles mainly consist of amyloid-β (Aβ) and tau protein, respectively. Most of the therapeutic strategies for AD to date have focused on Aβ. However, there is still no effective therapy available. In recent years, the clinical therapeutic failure of targeting Aβ pathology has resulted in increased interest towards tau-based therapeutics. In the current review, we focus on the research progress regarding the pathological mechanisms of tau protein in this disease and discuss tau-targeting therapeutic strategies.

A decrease in Fkbp52 alters autophagosome maturation and A152T-tau clearance in vivo

The failure of the autophagy-lysosomal pathway to clear the pathogenic forms of Tau exacerbates the pathogenesis of tauopathies. We have previously shown that the immunophilin FKBP52 interacts both physically and functionally with Tau, and that a decrease in FKBP52 protein levels is associated with Tau deposition in affected human brains. We have also shown that FKBP52 is physiologically present within the lysosomal system in healthy human neurons and that a decrease in FKBP52 expression alters perinuclear lysosomal positioning and Tau clearance during Tau-induced proteotoxic stress in vitro. In this study, we generate a zebrafish fkbp4 loss of function mutant and show that axonal retrograde trafficking of Lamp1 vesicles is altered in this mutant. Moreover, using our transgenic HuC::mCherry-EGFP-LC3 line, we demonstrate that the autophagic flux is impaired in fkbp4 mutant embryos, suggesting a role for Fkbp52 in the maturation of autophagic vesicles. Alterations in both axonal transport and autophagic flux are more evident in heterozygous rather than homozygous fkbp4 mutants. Finally, taking advantage of the previously described A152T-Tau transgenic fish, we show that the clearance of pathogenic A152T-Tau mutant proteins is slower in fkbp4 +/- mutants in comparison to fkbp4 +/+ larvae. Altogether, these results indicate that Fkbp52 is required for the normal trafficking and maturation of lysosomes and autophagic vacuoles along axons, and that its decrease is sufficient to hinder the clearance of pathogenic Tau in vivo.

Regulation of tau by peptidyl-prolyl isomerases

Tau is an intrinsically disordered protein found abundantly in axons, where it binds to microtubules. Since tau is a central player in the dynamic microtubule network, it is highly regulated by post-translational modifications. Abnormal hyperphosphorylation and aggregation of tau characterize a group of diseases called tauopathies. A specific protein family of cis/trans peptidyl-prolyl isomerases (PPIases) can interact with tau to regulate its aggregation and neuronal resilience. Structural interactions between tau and specific PPIases have been determined, establishing possible mechanisms for tau regulation and modification. While there have been numerous in vivo studies evaluating the impact of PPIase expression on tau biology/pathology, the direct roles of PPIases have yet to be fully characterized. Different PPIases correlate to either increased or decreased levels of tau-associated degeneration. Therefore, the ability of PPIases to structurally modify and regulate tau should be further investigated due to its potential therapeutic implications for Alzheimer's disease and other tauopathies.

Post-Traumatic Stress Disorder and Risk of Degenerative Synucleinopathies: Systematic Review and Meta-Analysis

OBJECTIVE

A systematic review was conducted to answer whether adult-onset post-traumatic stress disorder (PTSD) is associated with increased risk of Parkinson's disease (PD) and related synucleinopathies.

DESIGN

A systematic search of Medline (Ovid), Embase (Elsevier), PsycInfo (Ovid), Cochrane Library (Wiley), and Web of Science (Clarivate) was performed using MeSH headings and equivalent terms for PTSD, PD, DLB, and related disorders.

SETTING

No restrictions.

PARTICIPANTS

Eligible articles were published in peer-reviewed journals, sampled adult human populations, and treated PTSD and degenerative synucleinopathies as exposures and outcomes, respectively.

MEASUREMENTS

Extracted data included diagnostic methods, sample characteristics, matching procedures, covariates, and effect estimates. Bias assessment was performed with the Newcastle-Ottawa scale. Hazard ratios were pooled using the random effects model, and the Hartung-Knapp adjustment was applied due to the small number of studies.

RESULTS

A total of six articles comprising seven unique samples (total n = 1,747,378) met eligibility criteria. The risk of PD was reported in three retrospective cohort studies and one case-control study. Risk of DLB was reported in one retrospective cohort, one case-control, and one prospective cohort study. No studies addressed potential relationships with multiple system atrophy or pure autonomic failure. Meta-analysis of hazard ratios from four retrospective cohort studies supported the hypothesis that incident PTSD was associated with PD and DLB risk (pooled HR 1.88, 95% C.I. 1.08-3.24; p = 0.035).

CONCLUSIONS

The sparse literature to-date supports further investigations on the association of mid- to late-life PTSD with Parkinson's and related neurodegenerative disorders.

Concomitant Neuronal Tau Deposition and FKBP52 Decrease Is an Early Feature of Different Human and Experimental Tauopathies

BACKGROUND

Pathological tau proteins constitute neurofibrillary tangles that accumulate in tauopathies including Alzheimer's disease (AD), progressive supranuclear palsy (PSP), and familial frontotemporal lobar degeneration (FTLD-Tau). We previously showed that the FKBP52 immunophilin interacts functionally with tau and strongly decreases in AD brain neurons in correlation with tau deposition. We also reported that FKBP52 co-localizes with autophagy-lysosomal markers and an early pathological tau isoform in AD neurons, suggesting its involvement in autophagic tau clearance.

OBJECTIVE

Our objective was to evaluate if differences in neuronal FKBP52 expression levels and subcellular localization might be detected in AD, PSP, familial FTLD-Tau, and in the hTau-P301 S mouse model compared to controls.

METHODS

Cell by cell immunohistofluorescence analyses and quantification of FKBP52 were performed on postmortem brain samples of some human tauopathies and on hTau-P301 S mice spinal cords.

RESULTS

We describe a similar FKBP52 decrease and its localization with early pathological tau forms in the neuronal autophagy-lysosomal pathway in various tauopathies and hTau-P301 S mice. We find that FKBP52 decreases early during the pathologic process as it occurs in rare neurons with tau deposits in the marginally affected frontal cortex region of AD Braak IV brains and in the spinal cord of symptomless 1-month-old hTau-P301 S mice.

CONCLUSION

As FKBP52 plays a significant role in cellular signaling and conceivably in tau clearance, our data support the idea that the prevention of FKBP52 decrease or the restoration of its normal expression at early pathologic stages might represent a new potential therapeutic approach in tauopathies including AD, familial FTLD-Tau, and PSP.

Cross-talk between α-synuclein and the microtubule cytoskeleton in neurodegeneration

Looking at the puzzle that depicts the molecular determinants in neurodegeneration, many pieces are lacking and multiple interconnections among key proteins and intracellular pathways still remain unclear. Here we focus on the concerted action of α-synuclein and the microtubule cytoskeleton, whose interplay, indeed, is emerging but remains largely unexplored in both its physiology and pathology. α-Synuclein is a key protein involved in neurodegeneration, underlying those diseases termed synucleinopathies. Its propensity to interact with other proteins and structures renders the identification of neuronal death trigger extremely difficult. Conversely, the unbalance of microtubule cytoskeleton in terms of structure, dynamics and function is emerging as a point of convergence in neurodegeneration. Interestingly, α-synuclein and microtubules have been shown to interact and mediate cross-talks with other intracellular structures. This is supported by an increasing amount of evidence ranging from their direct interaction to the engagement of in-common partners and culminating with their respective impact on microtubule-dependent neuronal functions. Last, but not least, it is becoming even more clear that α-synuclein and tubulin work synergically towards pathological aggregation, ultimately resulting in neurodegeneration. In this respect, we supply a novel perspective towards the understanding of α-synuclein biology and, most importantly, of the link between α-synuclein with microtubule cytoskeleton and its impact for neurodegeneration and future development of novel therapeutic strategies.