The role of the Pin1-cis P-tau axis in the development and treatment of vascular contribution to cognitive impairment and dementia and preeclampsia

Tauopathies are neurodegenerative diseases characterized by deposits of abnormal Tau protein in the brain. Conventional tauopathies are often defined by a limited number of Tau epitopes, notably neurofibrillary tangles, but emerging evidence suggests structural heterogeneity among tauopathies. The prolyl isomerase Pin1 isomerizes cis P-tau to inhibit the development of oligomers, tangles and neurodegeneration in multiple neurodegenerative diseases such as Alzheimer's disease, traumatic brain injury, vascular contribution to cognitive impairment and dementia (VCID) and preeclampsia (PE). Thus, cis P-tau has emerged as an early etiological driver, blood marker and therapeutic target for multiple neurodegenerative diseases, with clinical trials ongoing. The discovery of cis P-tau and other tau pathologies in VCID and PE calls attention for simplistic classification of tauopathy in neurodegenerative diseases. These recent advances have revealed the exciting novel role of the Pin1-cis P-tau axis in the development and treatment of vascular contribution to cognitive impairment and dementia and preeclampsia.

FASN negatively regulates p65 expression by reducing its stability via Thr254 phosphorylation and isomerization by Pin1

FASN, the sole cytosolic enzyme responsible for de novo palmitate synthesis in mammalian cells, has been associated with poor prognosis in cancer and shown to cause drug and radiation resistance by upregulating DNA damage repair via suppression of p65 expression. Targeting FASN by repurposing proton pump inhibitors has generated impressive outcomes in triple-negative breast cancer patients. While p65 regulation of DNA damage repair was thought to be due to its suppression of poly(ADP-ribose) polymerase 1 gene transcription, the mechanism of FASN regulation of p65 expression was unknown. In this study, we show that FASN regulates p65 stability by controlling its phosphorylation at Thr254, which recruits the peptidyl-prolyl cis/trans isomerase Pin1 that is known to stabilize many proteins in the nucleus. This regulation is mediated by palmitate, the FASN catalytic product, not by FASN protein per se. This finding of FASN regulation of p65 stability via phosphorylation of Thr254 and isomerization by Pin1 implicates that FASN and its catalytic product palmitate may play an important role in regulating protein stability in general and p65 more specifically.

Prolyl isomerase Pin1 sculpts the immune microenvironment of colorectal cancer

Pin1, a peptide prolyl cis-trans isomerase, is overexpressed and/or overactivated in many human malignancies. However, whether Pin1 regulates the immunosuppressive TME has not been well defined. In this study, we detected the effect of Pin1 on immune cells and immune checkpoint PD-L1 in the TME of CRC and explored the anti-tumor efficacy of Pin1 inhibitor ATRA combined with PD-1 antibody. We found that Pin1 facilitated the immunosuppressive TME by raising the proportion of myeloid-derived suppressor cells (MDSCs) and declining the percentage of CD8+ T cells and CD4+ T cells. Pin1 restrained PD-L1 protein expression in CRC cells and the effect was tempered by endoplasmic reticulum (ER) stress inducers. Mechanically, Pin1 overexpression decreased the stability of PD-L1 and promoted its degradation by mitigating ER stress. Silencing or inhibiting Pin1 promoted PD-L1 protein expression by inducing ER stress. Hence, Pin1 inhibitor ATRA enhanced the anti-tumor efficacy of PD-1 antibody in the CRC allograft by upregulating PD-L1. Our results reveal the critical and pleiotropic effects of Pin1 on managing the immune cells and immune checkpoint PD-L1 in the TME of CRC, providing a new promising candidate for combination with immunotherapy.

A common molecular and cellular pathway in developing Alzheimer and cancer

Globally cancer and Alzheimer's disease (AD) are two major diseases and still, there is no clearly defined molecular mechanism. There is an opposite relation between cancer and AD which are the proportion of emerging cancer was importantly slower in AD patients, whereas slow emerging AD in patients with cancer. In cancer, regulation of cell mechanisms is interrupted by an increase in cell survival and proliferation, while on the contrary, AD is related to augmented neuronal death, that may be either produced by or associated with amyloid-β (Aβ) and tau deposition. Stated that the probability that disruption of mechanisms takes part in the regulation of cell survival/death and might be implicated in both diseases. The mechanism of actions such as DNA-methylation, genetic polymorphisms, or another mechanism of actions that induce alteration in the action of drugs with significant roles in resolving the finding to repair and live or die might take part in the pathogenesis of these two ailments. The functions of miRNA, p53, Pin1, the Wnt signaling pathway, PI3 KINASE/Akt/mTOR signaling pathway GRK2 signaling pathway, and the pathophysiological role of oxidative stress are presented in this review as potential candidates which hypothetically describe inverse relations between cancer and AD. Innovative materials almost mutual mechanisms in the aetiology of cancer and AD advocates novel treatment approaches. Among these treatment strategies, the most promising use treatment such as tyrosine kinase inhibitor, nilotinib, protein kinase C, and bexarotene.

Recent advances of Pin1 inhibitors as potential anticancer agents

Pin1 (proline isomerase peptidyl-prolyl isomerase NIMA-interacting-1), as a member of PPIase family, catalyzes cis-trans isomerization of pThr/Ser-Pro amide bonds of its substrate proteins, further regulating cell proliferation, division, apoptosis, and transformation. Pin1 is overexpressed in various cancers and is positively correlated with tumor initiation and progression. Pin1 inhibition can effectively reduce tumor growth and cancer stem cell expansion, block metastatic spread, and restore chemosensitivity, suggesting that targeting Pin1 may be an effective strategy for cancer treatment. Considering the promising therapeutic effects of Pin1 inhibitors on cancers, we herein are intended to comprehensively summarize the reported Pin1 inhibitors, mainly highlighting their structures, biological functions and binding modes, in hope of providing a reference for the future drug discovery.

Integrating computational methods guided the discovery of phytochemicals as potential Pin1 inhibitors for cancer: pharmacophore modeling, molecular docking, MM-GBSA calculations and molecular dynamics studies

Pin1 is a pivotal player in interactions with a diverse array of phosphorylated proteins closely linked to critical processes such as carcinogenesis and tumor suppression. Its axial role in cancer initiation and progression, coupled with its overexpression and activation in various cancers render it a potential candidate for the development of targeted therapeutics. While several known Pin1 inhibitors possess favorable enzymatic profiles, their cellular efficacy often falls short. Consequently, the pursuit of novel Pin1 inhibitors has gained considerable attention in the field of medicinal chemistry. In this study, we employed the Phase tool from Schrödinger to construct a structure-based pharmacophore model. Subsequently, 449,008 natural products (NPs) from the SN3 database underwent screening to identify compounds sharing pharmacophoric features with the native ligand. This resulted in 650 compounds, which then underwent molecular docking and binding free energy calculations. Among them, SN0021307, SN0449787 and SN0079231 showed better docking scores with values of -9.891, -7.579 and -7.097 kcal/mol, respectively than the reference compound (-6.064 kcal/mol). Also, SN0021307, SN0449787 and SN0079231 exhibited lower free binding energies (-57.12, -49.81 and -46.05 kcal/mol, respectively) than the reference ligand (-37.75 kcal/mol). Based on these studies, SN0021307, SN0449787, and SN0079231 showed better binding affinity that the reference compound. Further the validation of these findings, molecular dynamics simulations confirmed the stability of the ligand-receptor complex for 100 ns with RMSD ranging from 0.6 to 1.8 Å. Based on these promising results, these three phytochemicals emerge as promising lead compounds warranting comprehensive biological screening in future investigations. These compounds hold great potential for further exploration regarding their efficacy and safety as Pin1 inhibitors, which could usher in new avenues for combating cancer.

pH-sensitive niosomes for ATRA delivery: A promising approach to inhibit Pin1 in high-grade serous ovarian cancer

The peptidyl-prolyl cis/trans isomerase Pin1 positively regulates numerous cancer-driving pathways, and it is overexpressed in several malignancies, including high-grade serous ovarian cancer (HGSOC). The findings that all-trans retinoic acid (ATRA) induces Pin1 degradation strongly support that ATRA treatment might be a promising approach for HGSOC targeted therapy. Nevertheless, repurposing ATRA into the clinics for the treatment of solid tumors remains an unmet need mainly due to the insurgence of resistance and its ineffective delivery. In the present study, niosomes have been employed for improving ATRA delivery in HGSOC cell lines. Characterization of niosomes including hydrodynamic diameter, ζ-potential, morphology, entrapment efficiency and stability over time and in culture media was performed. Furthermore, pH-sensitiveness and ATRA release profile were investigated to demonstrate the capability of these vesicles to release ATRA in a stimuli-responsive manner. Obtained results documented a nanometric and monodispersed samples with negative ζ-potential. ATRA was efficiently entrapped, and a substantial release was observed in the presence of acidic pH (pH 5.5). Finally, unloaded niosomes showed good biocompatibility while ATRA-loaded niosomes significantly increased ATRA Pin1 inhibitory activity, which was consistent with cell growth inhibition. Taken together, ATRA-loaded niosomes might represent an appealing therapeutic strategy for HGSOC therapy.

Prolyl isomerase Pin1 promotes autophagy and cancer cell viability through activating FoxO3 signalling

Pin1-directed prolyl isomerization is a central common oncogenic mechanism to drive tumorigenic processes. However, the role of Pin1 in cellular autophagy is still poorly understood. Here we report that pharmacological inhibition of Pin1 decreased the formation of autophagosome/autolysosomes upon nutrient starvation. Inhibition of Pin1 reduced, whereas forced expression of Pin1 increased, the level of LC3 and viability of U2OS and PANC-1 cells. Pin1 could augment the accumulation of LC3 upon chloroquine treatment, while chloroquine also disturbed its function on cell viability. RNA-Seq and qPCR identified altered autophagic pathway upon Pin1 silencing. Mechanistically, FoxO3 was identified critical for Pin1-mediated autophagy. Knockdown of FoxO3 could rescue the changes of LC3 level and cellular viability caused by Pin1 overexpression. In xenograft mouse model, Pin1 reduced the sensitivity of PANC-1 to chloroquine while FoxO3 silencing could inhibit Pin1's function. Moreover, Pin1 could bind FoxO3 via its pS284-P motif, reduce its phosphorylation at T32, facilitate its nuclear retention, and therefore increased its transcriptional activity. S284A mutation of FoxO3 interfered with its T32 phosphorylation, reduced its nuclear localization and disrupted its function to support cell viability upon nutrient starvation. Furthermore, the protein level of Pin1 positively correlated with FoxO3 nuclear localization and LC3 level in pancreatic adenocarcinoma and osteosarcoma samples. Together, this study highlights an important role for Pin1-FoxO3 axis in regulating autophagy and cancer cell viability. Intervening in the Pin1-FoxO3 interaction would serve as an effective therapeutic strategy and the pS284-P motif of FoxO3 provides a potential target for drug design.

Upregulation of Pin1 contributes to alleviation of cognitive dysfunction in diabetic mice

OBJECTIVE

This study aimed to explore the molecular mechanism underlying the role of Pin1 in cognitive dysfunction in diabetic mice.

METHODS

Using a streptozotocin-induced diabetic mouse model, an adeno-associated virus carrying the Pin1 gene was used to upregulate Pin1 expression in the hippocampus of diabetic mice. Animal behavior tests and molecular biology techniques were further used to explore the role of Pin1 in cognitive dysfunction in diabetic mice.

RESULTS

Our study demonstrated that upregulation of Pin1 expression increased the phosphorylation of AKT and insulin receptor substrate 1 downstream signaling molecules of the IR-IGF1R pathway, increased the phosphorylation of GSK-3β, and concomitantly decreased the phosphorylation of Tau in the hippocampus of diabetic mice, thereby improving the ultrastructural pathology of the hippocampus and further alleviating diabetes-related cognitive impairment.

CONCLUSION

Pin1 can improve cognitive dysfunction in diabetic mice.

Long-term normalization of calcineurin activity in model mice rescues Pin1 and attenuates Alzheimer's phenotypes without blocking peripheral T cell IL-2 response

BACKGROUND

Current treatments for Alzheimer's disease (AD) have largely failed to yield significant therapeutic benefits. Novel approaches are desperately needed to help address this immense public health issue. Data suggests that early intervention at the first stages of mild cognitive impairment may have a greater chance for success. The calcineurin (CN)-Pin1 signaling cascade can be selectively targeted with tacrolimus (FK506), a highly specific, FDA-approved CN inhibitor used safely for > 20 years in solid organ transplant recipients. AD prevalence was significantly reduced in solid organ recipients treated with FK506.

METHODS

Time release pellets were used to deliver constant FK506 dosage to APP/PS1 mice without deleterious manipulation or handling. Immunofluorescence, histology, molecular biology, and behavior were used to evaluate changes in AD pathology.

RESULTS

FK506 can be safely and consistently delivered into juvenile APP/PS1 mice via time-release pellets to levels roughly seen in transplant patients, leading to the normalization of CN activity and reduction or elimination of AD pathologies including synapse loss, neuroinflammation, and cognitive impairment. Pin1 activity and function were rescued despite the continuing presence of high levels of transgenic Aβ42. Indicators of neuroinflammation including Iba1 positivity and IL-6 production were also reduced to normal levels. Peripheral blood mononuclear cells (PBMC) obtained during treatment or splenocytes isolated at euthanasia activated normally after mitogens.

CONCLUSIONS

Low-dose, constant FK506 can normalize CNS CN and Pin1 activity, suppress neuroinflammation, and attenuate AD-associated pathology without blocking peripheral IL-2 responses making repurposed FK506 a viable option for early, therapeutic intervention in AD.

Oxygen-independent stabilization of HIF-2α in breast cancer through direct interaction with peptidyl-prolyl cis-trans isomerase NIMA-interacting 1

Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) isomerizes the nearby proline (Pro) residue when it detects phosphorylated serine (Ser) or threonine (Thr) of target proteins, altering their structure, stability, function, and interaction with other proteins. Hypoxia-inducible factor 2α (HIF-2α), a transcription factor that transactivates many oncogenic genes under hypoxic conditions, harbours the pSer/Thr-Pro motif. We found for the first time that Pin1 binds to HIF-2α physically in normoxic as well as hypoxic conditions in human breast cancer cells. The level of ubiquitinated HIF-2α was significantly raised by Pin1 knockdown, while expression of its mRNA transcript was unaffected. In agreement with this observation, the cycloheximide chase assay demonstrated that Pin1 prolonged the stability of HIF-2α. Serine 672, 696, and 790 of HIF-2α were found to undergo phosphorylation. Of these, the main amino acid involved in the Pin1 binding and HIF-2α stabilization was identified as serine 790, located in the nuclear export signal region of HIF-2α. The tissue array with human breast cancer specimens showed elevated expression of HIF-2α as well as Pin1 compared to adjacent normal tissues. Knockdown of Pin1 or HIF-2α diminished breast cancer cell migration and colony formation. In conclusion, Pin1 stabilizes HIF-2α through direct interaction, which contributes to the growth of breast cancer.

Sufentanil inhibits Pin1 to attenuate renal tubular epithelial cell ischemia-reperfusion injury by activating the PI3K/AKT/FOXO1 pathway

BACKGROUND

Renal ischemia-reperfusion injury (RIRI) has become a great concern in clinical practice with high morbidity and mortality rates. Sufentanil has protective effects on IRI-induced organ injury. Herein, the effects of sufentanil on RIRI were investigated.

METHODS

RIRI cell model was established by hypoxia/reperfusion (H/R) stimulation. The mRNA and protein expressions were assessed using qRT-PCR and western blot. TMCK-1 cell viability and apoptosis were assessed using MTT assay and flow cytometry, respectively. The mitochondrial membrane potential and ROS level were detected by JC-1 mitochondrial membrane potential fluorescent probe and DCFH-DA fluorescent probe, respectively. LDH, SOD, CAT, GSH and MDA levels were determined by the kits. The interaction between FOXO1 and Pin1 promoter was analyzed using dual luciferase reporter gene and ChIP assays.

RESULTS

Our results revealed that sufentanil treatment attenuated H/R-induced cell apoptosis, mitochondrial membrane potential (MMP) dysfunction, oxidative stress, inflammation and activated PI3K/AKT/FOXO1 associated proteins, while these effects were reversed by PI3K inhibitor, suggesting that sufentanil attenuated RIRI via activating the PI3K/AKT/FOXO1 signaling pathway. We subsequently found that FOXO1 transcriptionally activated Pin1 in TCMK-1 cells. Pin1 inhibition ameliorated H/R-induced TCMK-1 cell apoptosis, oxidative stress and inflammation. In addition, as expected, the biological effects of sufentanil on H/R-treated TMCK-1 cells were abrogated by Pin1 overexpression.

CONCLUSION

Sufentanil reduced Pin1 expression through activation of the PI3K/AKT/FOXO1 signaling to suppress cell apoptosis, oxidative stress and inflammation in renal tubular epithelial cells during RIRI development.

Hepatic Pin1 Expression, Particularly in Nuclei, Is Increased in NASH Patients in Accordance with Evidence of the Role of Pin1 in Lipid Accumulation Shown in Hepatoma Cell Lines

Our previous studies using rodent models have suggested an essential role for Pin1 in the pathogenesis of non-alcoholic steatohepatitis (NASH). In addition, interestingly, serum Pin1 elevation has been reported in NASH patients. However, no studies have as yet examined the Pin1 expression level in human NASH livers. To clarify this issue, we investigated the expression level and subcellular distribution of Pin1 in liver specimens obtained using needle-biopsy samples from patients with NASH and healthy liver donors. Immunostaining using anti-Pin1 antibody revealed the Pin1 expression level to be significantly higher, particularly in nuclei, in the livers of NASH patients than those of healthy donors. In the samples from patients with NASH, the amount of nuclear Pin1 was revealed to be negatively related to serum alanine aminotransferase (ALT), while tendencies to be associated with other serum parameters such as aspartate aminotransferase (AST) and platelet number were noted but did not reach statistical significance. Such unclear results and the lack of a significant relationship might well be attributable to our small number of NASH liver samples (n = 8). Moreover, in vitro, it was shown that addition of free fatty acids to medium induced lipid accumulation in human hepatoma HepG2 and Huh7 cells, accompanied with marked increases in nuclear Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1), in accordance with the aforementioned observations in human NASH livers. In contrast, suppression of Pin1 gene expression using siRNAs attenuated the free fatty acid-induced lipid accumulation in Huh7 cells. Taken together, these observations strongly suggest that increased expression of Pin1, particularly in hepatic nuclei, contributes to the pathogenesis of NASH with lipid accumulation.

Prolyl isomerase Pin1 promotes extracellular matrix production in hepatic stellate cells through regulating formation of the Smad3-TAZ complex

Hepatic stellate cells (HSCs) produce extracellular matrixes (ECMs), such as collagen and fibronectin, in response to stimulation with transforming growth factor β (TGFβ). The massive ECM accumulation in the liver due to HSCs causes fibrosis which eventually leads to hepatic cirrhosis and hepatoma development. However, details of the mechanisms underlying continuous HSC activation are as yet poorly understood. We thus attempted to elucidate the role of Pin1, one of the prolyl isomerases, in the underlying mechanism(s), using the human HSC line LX-2. Treatment with Pin1 siRNAs markedly alleviated the TGFβ-induced expressions of ECM components such as collagen 1a1/2, smooth muscle actin and fibronectin at both the mRNA and the protein level. Pin1 inhibitors also decreased the expressions of fibrotic markers. In addition, it was revealed that Pin1 associates with Smad2/3/4, and that four Ser/Thr-Pro motifs in the linker domain of Smad3 are essential for binding with Pin1. Pin1 significantly regulated Smad-binding element transcriptional activity without affecting Smad3 phosphorylations or translocation. Importantly, both Yes-associated protein (YAP) and WW domain-containing transcription regulator (TAZ) also participate in ECM induction, and upregulate Smad3 activity rather than TEA domain transcriptional factor transcriptional activity. Although Smad3 interacts with both TAZ and YAP, Pin1 facilitates the Smad3 association with TAZ, but not that with YAP. In conclusion, Pin1 plays pivotal roles in ECM component productions in HSCs through regulation of the interaction between TAZ and Smad3, and Pin1 inhibitors may have the potential to ameliorate fibrotic diseases.

Thymol improves autism-like behaviour in VPA-induced ASD rats through the Pin1/p38 MAPK pathway

Inflammation plays an essential role in the pathogenesis of autism spectrum disorder (ASD). Thymol is a bioactive monoterpene isolated from Thymus vulgaris that has anti-inflammatory properties and is helpful in neurodevelopmental disorders. The purpose of this study was to investigate the effects of thymol on autism-like behaviours in rats with VPA-induced ASD and to assess the related molecular mechanisms. In the prefrontal cortex (PFC) of the valproic acid (VPA)-exposed rat model, the levels of Pin1, phosphorylated p38 MAPK, interleukin-1β (IL-1β) and tumour necrosis factor (TNF)-α, were increased, and the levels of PSD95 and synaptophysin (SYP) decreased. After thymol treatment (30 mg/kg), the VPA-induced autism-like behaviours were alleviated. Moreover, thymol also rescued the dysregulated levels of Pin1, phosphorylated p38 MAPK, IL-1β, TNF-α, PSD95, and SYP. In addition, immunofluorescence experiments showed that thymol treatment decreased the correlation between Pin1 and phosphorylated p38 MAPK. Mechanistically, Pin1 knockdown by RNA interference confirmed that Pin1 promotes inflammation via phosphorylation of p38 MAPK in the VPA exposure rat model. In conclusion, thymol improved autism-like behaviours in VPA-induced ASD rats by reducing inflammation and improving neurodevelopment. This effect was mediated by the Pin1/p38 MAPK pathway. These results experimentally provide the potential for thymol in new therapeutic avenues for autism.

Juglone Inhibits Tumor Metastasis by Regulating Stemness Characteristics and the Epithelial-to-Mesenchymal Transition in Cancer Cells both in Vitro and in Vivo

BACKGROUND

The stemness characteristics of cancer cells, such as self-renewal and tumorigenicity, are considered to be responsible, in part, for tumor metastasis. Epithelial-to-mesenchymal transition (EMT) plays an important role in promoting both stemness and tumor metastasis. Although the traditional medicine juglone is thought to play an anticancer role by affecting cell cycle arrest, induction of apoptosis, and immune regulation, a potential function of juglone in regulating cancer cell stemness characteristics remains unknown.

METHODS

In the present study, tumor sphere formation assay and limiting dilution cell transplantation assays were performed to assess the function of juglone in regulating maintenance of cancer cell stemness characteristics. EMT of cancer cells was assessed by western blot and transwell assay in vitro, and a liver metastasis model was also performed to demonstrate the effect of juglone on colorectal cancer cells in vivo.

RESULTS

Data gathered indicates juglone inhibits stemness characteristics and EMT in cancer cells. Furthermore, we verified that metastasis was suppressed by juglone treatment. We also observed that these effects were, in part, achieved by inhibiting Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1).

CONCLUSIONS

These results indicate that juglone inhibits maintenance of stemness characteristics and metastasis in cancer cells.

Spastin Promotes the Migration and Invasion Capability of T98G Glioblastoma Cells by Interacting with Pin1 through Its Microtubule-Binding Domain

Microtubule-severing protein Spastin has been shown to co-localize with actin in migratory glioblastoma cells and is linked to glioblastomas' migration and invasion capacity. However, the effectiveness of Spastin in glioblastoma migration and the molecular mechanism underpinning the orientation of Spastin towards actin filaments remain unknown. Here, we demonstrated that Spastin plays an active role in glioblastoma migration by showing a reduced migratory potential of T98G glioblastoma cells using real-time cell analysis (RTCA) in Spastin-depleted cells. Pull-down assays revealed that a cis-trans isomerase Pin1 interacts with Spastin through binding to the phosphorylated Pin1 recognition motifs in the microtubule-binding domain (MBD), and immunocytochemistry analysis showed that interaction with Pin1 directs Spastin to actin filaments in extended cell regions. Consequently, by utilizing RTCA, we proved that the migration and invasion capacity of T98G glioblastoma cells significantly increased with the overexpression of Spastin, of which the Pin1 recognition motifs in MBD are constitutively phosphorylated, while the overexpression of phospho-mutant form did not have a significant effect on migration and invasion of T98G glioblastoma cells. These findings demonstrate that Pin1 is a novel interaction partner of Spastin, and their interaction drives Spastin to actin filaments, allowing Spastin to contribute to the glioblastomas' migration and invasion abilities.

Stress Activated MAP Kinases and Cyclin-Dependent Kinase 5 Mediate Nuclear Translocation of Nrf2 via Hsp90α-Pin1-Dynein Motor Transport Machinery

Non-lethal low levels of oxidative stress leads to rapid activation of the transcription factor nuclear factor-E2-related factor 2 (Nrf2), which upregulates the expression of genes important for detoxification, glutathione synthesis, and defense against oxidative damage. Stress-activated MAP kinases p38, ERK, and JNK cooperate in the efficient nuclear accumulation of Nrf2 in a cell-type-dependent manner. Activation of p38 induces membrane trafficking of a glutathione sensor neutral sphingomyelinase 2, which generates ceramide upon depletion of cellular glutathione. We previously proposed that caveolin-1 in lipid rafts provides a signaling hub for the phosphorylation of Nrf2 by ceramide-activated PKCζ and casein kinase 2 to stabilize Nrf2 and mask a nuclear export signal. We further propose a mechanism of facilitated Nrf2 nuclear translocation by ERK and JNK. ERK and JNK phosphorylation of Nrf2 induces the association of prolyl cis/trans isomerase Pin1, which specifically recognizes phosphorylated serine or threonine immediately preceding a proline residue. Pin1-induced structural changes allow importin-α5 to associate with Nrf2. Pin1 is a co-chaperone of Hsp90α and mediates the association of the Nrf2-Pin1-Hsp90α complex with the dynein motor complex, which is involved in transporting the signaling complex to the nucleus along microtubules. In addition to ERK and JNK, cyclin-dependent kinase 5 could phosphorylate Nrf2 and mediate the transport of Nrf2 to the nucleus via the Pin1-Hsp90α system. Some other ERK target proteins, such as pyruvate kinase M2 and hypoxia-inducible transcription factor-1, are also transported to the nucleus via the Pin1-Hsp90α system to modulate gene expression and energy metabolism. Notably, as malignant tumors often express enhanced Pin1-Hsp90α signaling pathways, this provides a potential therapeutic target for tumors.

Expression, Purification, Structural and Functional Characterization of Recombinant Human Parvulin 17

Parvulins, peptidyl-prolyl isomerase enzymes (PPIase), catalyze the cis-trans isomerization of prolyl bonds in polypeptides, contributing to folding and function regulation of many proteins. Among Parvulins, Par17, exclusively expressed in hominids, is the least examined in terms of structure, catalytic function and cellular activity. Setting the conditions for the preparation of recombinant active Par17 may therefore significantly foster future studies. Here, we comparatively evaluated the impact of several parameters, including host strains, culture media, isopropyl ß-D-1-thiogalactopyranoside concentration, post-induction incubation time and temperature, on the overexpression of Par17 in E. coli cells. A similar approach was also comparatively adopted for the preparation of the recombinant full-length Pin1 protein, the most representative Parvulin, and the catalytic domains of both enzymes. Proteins were efficiently expressed and purified to homogeneity and were subjected to a structural characterization by Size Exclusion Chromatography and Circular Dichroism. Moreover, a single-step homogeneous protease-based fluorimetric assay, potentially scalable in HTS format, has been developed for determining the peptidyl-prolyl cis-trans isomerase activity of recombinant Parvulins. Results obtained show that proteins are folded and active. These new data mark an important milestone for progressing the investigation of Parvulins.

3D dynamic cultures of HGSOC organoids to model innovative and standard therapies

High-grade serous ovarian cancer (HGSOC) needs new technologies for improving cancer diagnosis and therapy. It is a fatal disease with few options for the patients. In this context, dynamic culture systems coupling with patient-derived cancer 3D microstructures could offer a new opportunity for exploring novel therapeutic approaches. In this study, we optimized a passive microfluidic platform with 3D cancer organoids, which allows a standardized approach among different patients, a minimum requirement of samples, multiple interrogations of biological events, and a rapid response. The passive flow was optimized to improve the growth of cancer organoids, avoiding the disruption of the extracellular matrix (ECM). Under optimized conditions of the OrganoFlow (tilting angle of 15° and an interval of rocking every 8 min), the cancer organoids grow faster than when they are in static conditions and the number of dead cells is reduced over time. To calculate the IC ₅₀ values of standard chemotherapeutic drugs (carboplatin, paclitaxel, and doxorubicin) and targeted drugs (ATRA), different approaches were utilized. Resazurin staining, ATP-based assay, and DAPI/PI colocalization assays were compared, and the IC ₅₀ values were calculated. The results showed that in the passive flow, the IC ₅₀ values are lower than in static conditions. FITC-labeled paclitaxel shows a better penetration of ECM under passive flow than in static conditions, and cancer organoids start to die after 48 h instead of 96 h, respectively. Cancer organoids are the last frontiers for ex vivo testing of drugs that replicate the response of patients in the clinic. For this study, organoids derived from ascites or tissues of patients with Ovarian Cancer have been used. In conclusion, it was possible to develop a protocol for organoid cultures in a passive microfluidic platform with a higher growth rate, faster drug response, and better penetration of drugs into ECM, maintaining the samples' vitals and collecting the data on the same plate for up to 16 drugs.

Molecular docking, 3D-QASR and molecular dynamics simulations of thiazoles Pin1 inhibitors

Pin1 (protein interacting with never-in-mitosis akinase-1) is a member of the PPIase (peptidylprolyl cis-trans isomerase) family. It can interact with a variety of carcinogenic or tumor suppressive phosphorylated proteins. The interaction results in the conformational changes of target proteins, and ultimately regulates the activity of these proteins. These activity changes play a key role in tumorigenesis. Pin1 is an attractive target for cancer therapy due to its over-expression and/or activation in various types of cancer and the disorder of Proline directed phosphorylation. In this study, molecular docking, three-dimensional quantitative structure-activity relationship (3D-QSAR) and molecular dynamics (MD) simulations were performed to investigate the structure-activity relationship and binding mechanism of 45 thiazole-class Pin1 inhibitors. Molecular docking studies predict the binding mode and the interactions between the ligand and the receptor protein. The results of the 3 D-QSAR model show that electrostatic field, hydrophobic field and hydrogen bond play important roles in the binding process of inhibitors to protein. Molecular dynamics simulation results reveal that the complex of the ligand and the receptor protein are stable at 300 K. The binding free energy calculation and energy decomposition results show that His59, Cys113, Ser114, Ser115, Leu122, Met130, Gln131, Phe134, Ser154 and His157 may be the key to the inhibitor binding to Pin1 protein. This study provides an important theoretical basis for further development of the new Pin1 inhibitor design. These results can provide more useful information for our further drug design. Communicated by Ramaswamy H. Sarma.

Prolyl Isomerase, Pin1, Controls Meiotic Progression in Mouse Oocytes

During meiotic maturation, accurate progression of meiosis is ensured by multiple protein kinases and by signal transduction pathways they are involved in. However, the mechanisms regulating the functions of phosphorylated proteins are unclear. Herein, we investigated the role of Pin1, a peptidyl-prolyl cis-trans isomerase family member that regulates protein functions by altering the structure of the peptide bond of proline in phosphorylated proteins in meiosis. First, we analyzed changes in the expression of Pin1 during meiotic maturation and found that although its levels were constant, its localization was dynamic in different stages of meiosis. Furthermore, we confirmed that the spindle rotates near the cortex when Pin1 is inhibited by juglone during meiotic maturation, resulting in an error in the extrusion of the first polar body. In Pin1^-/- mice, frequent polar body extrusion errors were observed in ovulation, providing insights into the mechanism underlying the errors in the extrusion of the polar body. Although multiple factors and mechanisms might be involved, Pin1 functions in meiosis progression via actin- and microtubule-associated phosphorylated protein targets. Our results show that functional regulation of Pin1 is indispensable in oocyte production and should be considered while developing oocyte culture technologies for reproductive medicine and animal breeding.

Novel pH-sensitive nanoparticles based on prodrug strategy to delivery All-Trans Retinoic Acid for breast cancer

Developing chemotherapy with nanoparticle-based prodrugs provides promising strategies for improving the safety and delivery of anti-cancer drugs therapeutics and effective cancer treatment. Herein, we developed a pH-sensitive prodrug delivery system (All-Trans-Retinoic Acid (ATRA) grafted poly (β-amino esters) (PBAE) copolymers, ATRA-g-PBAE) for delivery of ATRA with some physicochemical and biological properties. The in vitro release of ATRA-g-PBAE prodrug nanoparticles (PNPs) was sustained-release and pH-sensitive. The cytotoxicity and uptake of different preparations in vitro were evaluated on MCF-7 cells at pH 7.4 and 5.5. The carrier PBAE had no cytotoxicity, and ATRA-g-PBAE PNPs could significantly inhibit cell growth at pH 5.5. MCF-7 cells treated with Cy5.5 grafted PBAE (Cy5.5-PBAE) showed stronger fluorescence signals at pH 5.5. Meanwhile, ATRA-g-PBAE PNPs entered the cell via a clathrin-mediated endocytic pathway. Subsequently, PBAE protonation facilitated the escape of PNPs from the lysosome and released the drug. ATRA-g-PBAE seems promising as a novel pH-sensitive prodrug to overcome the limitations of ATRA for breast cancer therapy.

Roles of peptidyl prolyl isomerase Pin1 in viral propagation

Peptidyl-prolyl isomerase (PPIase) is a unique enzyme that promotes cis-trans isomerization of a proline residue of a target protein. Peptidyl-prolyl cis-trans isomerase NIMA (never in mitosis A)-interacting 1 (Pin1) is a PPIase that binds to the pSer/pThr-Pro motif of target proteins and isomerizes their prolines. Pin1 has been reported to be involved in cancer development, obesity, aging, and Alzheimer's disease and has been shown to promote the growth of several viruses including SARS-CoV-2. Pin1 enhances the efficiency of viral infection by promoting uncoating and integration of the human immunodeficiency virus. It has also been shown that Pin1 interacts with hepatitis B virus proteins and participates in viral replication. Furthermore, Pin1 promotes not only viral proliferation but also the progression of virus-induced tumorigenesis. In this review, we focus on the effects of Pin1 on the proliferation of various viruses and discuss the underlying molecular mechanisms.

MicroRNA-140-5p inhibitor attenuates memory impairment induced by amyloid-ß oligomer in vivo possibly through Pin1 regulation

AIMS

The peptidyl-prolyl cis/trans isomerase, Pin1, has a protective role in age-related neurodegeneration by targeting different phosphorylation sites of tau and the key proteins required to produce Amyloid-β, which are the well-known molecular signatures of Alzheimer's disease (AD) neuropathology. The direct interaction of miR-140-5p with Pin1 mRNA and its inhibitory role in protein translation has been identified. The main purpose of this study was to investigate the role of miRNA-140-5p inhibition in promoting Pin1 expression and the therapeutic potential of the AntimiR-140-5p in the Aß oligomer (AßO)-induced AD rat model.

METHODS

Spatial learning and memory were assessed in the Morris water maze. RT-PCR, western blot, and histological assays were performed on hippocampal samples at various time points after treatments. miRNA-140-5p inhibition enhanced Pin1 and ADAM10 mRNA expressions but has little effect on Pin1 protein level.

RESULTS

The miRNA-140-5p inhibitor markedly ameliorated spatial learning and memory deficits induced by AßO, and concomitantly suppressed the mRNA expression of inflammatory mediators TNFα and IL-1β, and phosphorylation of tau at three key sites (thr231, ser396, and ser404) as well as increased phosphorylated Ser473-Akt.

CONCLUSION

According to our results, Antimir-140-mediated improvement of AβO-induced neuronal injury and memory impairment in rats may provide an appropriate rationale for evaluating miR-140-5p inhibitors as a promising agent for the treatment of AD.

Pin1-mediated regulation of articular cartilage stem/progenitor cell aging

Cartilage stem/progenitor cells (CSPCs) was recently isolated and identified from the cartilage tissue. CSPCs is essential for repair and regeneration of cartilage in osteoarthritis (OA). Aging is a primary risk factor for cartilage damage and joint OA. Although studies have confirmed the link between cell aging and OA, the underlying molecular mechanisms regulating CSPCs aging are not fully understood. In this study, we investigated the role of Pin1 in the aging of rat knee joint CSPCs. We isolated CSPCs from rat knee joints and demonstrated that, in long-term in vitro culture, Pin1 protein levels are significantly reduced. At the same time, expression of the senescence-related β-galactosidase and the senescence marker p16^INK4A were markedly elevated. In addition, Pin1 overexpression reversed the progression of cellular senescence, as evidenced by the down-regulation of senescence-related β-galactosidase, increased EdU positive cells and diminished levels of p16^INK4A. In contrast, Pin1 siRNA incorporation promoted CSPCs senescence. In addition, we also observed the distribution of cell cycles through flow cytometry and revealed that Pin1 deficiency results in cell cycle arrest in the G1 phase, suggesting severe lack of proliferation ability, a sign of cellular senescence. Collectively, these results validated that Pin1 is an essential regulator of CSPCs aging.

Spinal Cord Injury Causes Prominent Tau Pathology Associated with Brain Post-Injury Sequela

Spinal cord injury (SCI) can result in significant neurological impairment and functional and cognitive deficits. It is well established that SCI results in focal neurodegeneration that gradually spreads to other cord areas. On the other hand, traumatic brain injury (TBI) is strongly associated with tau protein pathology and neurodegeneration that can spread in areas throughout the brain. Tau is a microtubule-associated protein abundant in neurons and whose abnormalities result in neuronal cell death. While SCI and TBI have been extensively studied, there is limited research on the relationship between SCI and brain tau pathology. As a result, in this study, we examined tau pathology in spinal cord and brain samples obtained from severe SCI mouse models at various time points. The effects of severe SCI on locomotor function, spatial memory, anxiety/risk-taking behavior were investigated. Immunostaining and immunoblotting confirmed a progressive increase in tau pathology in the spinal cord and brain areas. Moreover, we used electron microscopy to examine brain samples and observed disrupted mitochondria and microtubule structure following SCI. SCI resulted in motor dysfunction, memory impairment, and abnormal risk-taking behavior. Notably, eliminating pathogenic cis P-tau via systemic administration of appropriate monoclonal antibodies restored SCI's pathological and functional consequences. Thus, our findings suggest that SCI causes severe tauopathy that spreads to brain areas, indicating brain dysfunction. Additionally, tau immunotherapy with an anti-cis P-tau antibody could suppress pathogenic outcomes in SCI mouse models, with significant clinical implications for SCI patients. SCI induces profound pathogenic cis p-tau, which diffuses into the brain through CSF, resulting in brain neurodegeneration and cognitive decline.

Cinobufacini Injection Inhibits the Proliferation of Triple-Negative Breast Cancer Through the Pin1-TAZ Signaling Pathway

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer (BC), which is characterized by the total absence of human epidermal growth factor receptor 2 (HER2), progesterone receptor (PR), and estrogen receptor (ER) expression. Cinobufacini injection (CI) is the aqueous extract from the dry skin of Bufo gargarizans, which is broadly used for the treatment of malignant tumors. However, the potential mechanism of CI against TNBC has not been fully revealed. In this study, we found that CI inhibited the proliferation of MDA-MB-231 and 4T1 cells in a time- and dose-dependent manner. RNA-seq data showed that downregulated and upregulated genes were mainly enriched in biological processes related to tumor cell proliferation, including cell cycle arrest and regulation of apoptosis signaling pathways. Indeed, after CI treatment, the protein level of CDK1 and Bcl-2/Bax decreased, indicating that CI induced the cell cycle of MDA-MB-231 arrest in the G2/M phase and increased the rate of apoptosis. Meanwhile, CI significantly inhibited the growth of tumor in vivo, and RNA-seq data showed that the TAZ signaling pathway played a vital role after CI treatment. Both immunohistochemistry and Western blot analysis confirmed the downregulation of Pin1 and TAZ, caused by CI treatment. Furthermore, the bioinformatics analysis indicated that Pin1 and TAZ were indeed elevated in TNBC patients, with poor staging, classification, and patient survival rate. In conclusion, CI effectively inhibited the proliferation of TNBC in vitro and in vivo and induced their apoptosis and cycle arrest through the Pin1–TAZ pathway.

Establishment of a Zebrafish Xenograft Model for in Vivo Investigation of Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is a unique malignant tumor of the head and neck. Despite higher survival rates by the combination of radiotherapy and chemotherapy, the recurrence or metastasis of NPC still occurs at about 10%. Therefore, there is urgent demand to develop more effective in vivo models for preclinical trials to investigate the mechanisms of NPC development and progression and to explore better treatment approaches. In this study, we transplanted human NPC CNE1 cells into zebrafish embryos to establish a xenograft model of NPC, where the proliferation and invasion behaviors of NPC cells were investigated in vivo. Combining in vitro and in vivo analyses, we found that activating transcription factor 7 (ATF7) was involved in the occurrence and development of NPC regulated by peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1). The zebrafish NPC xenograft model established here thereby provides an in vivo tool for exploring the occurrence and development of NPC, which may help to identify new tumor markers and develop new therapeutic strategies for the treatment of NPC.

Pin1 as Molecular Switch in Vascular Endothelium: Notes on Its Putative Role in Age-Associated Vascular Diseases

By controlling the change of the backbones of several cellular substrates, the peptidyl-prolyl cis-trans isomerase Pin1 acts as key fine-tuner and amplifier of multiple signaling pathways, thereby inducing several biological consequences, both in physiological and pathological conditions. Data from the literature indicate a prominent role of Pin1 in the regulating of vascular homeostasis. In this review, we will critically dissect Pin1’s role as conformational switch regulating the homeostasis of vascular endothelium, by specifically modulating nitric oxide (NO) bioavailability. In this regard, Pin1 has been reported to directly control NO production by interacting with bovine endothelial nitric oxide synthase (eNOS) at Ser¹¹⁶-Pro¹¹⁷ (human equivalent is Ser¹¹⁴-Pro¹¹⁵) in a phosphorylation-dependent manner, regulating its catalytic activity, as well as by regulating other intracellular players, such as VEGF and TGF-β, thereby impinging upon NO release. Furthermore, since Pin1 has been found to act as a critical driver of vascular cell proliferation, apoptosis, and inflammation, with implication in many vascular diseases (e.g., diabetes, atherosclerosis, hypertension, and cardiac hypertrophy), evidence indicating that Pin1 may serve a pivotal role in vascular endothelium will be discussed. Understanding the role of Pin1 in vascular homeostasis is crucial in terms of finding a new possible therapeutic player and target in vascular pathologies, including those affecting the elderly (such as small and large vessel diseases and vascular dementia) or those promoting the full expression of neurodegenerative dementing diseases.

RETSAT Mutation Selected for Hypoxia Adaptation Inhibits Tumor Growth

Hypoxia occurs not only in natural environments including high altitude, underground burrows and deep sea, but also in human pathological conditions, such as hypoxic solid tumors. It has been well documented that hypoxia related signaling pathway is associated with a poor clinical outcome. Our group has recently identified multiple novel genes critical for solid tumor growth comparing the genome-wide convergent/parallel sequence evolution of highland mammals. Among them, a single mutation on the retinol saturase gene (RETSAT) containing amino acid switch from glutamine (Q) to arginine (R) at the position 247 was identified. Here, we demonstrate that RETSAT is mostly downregulated in multiple types of human cancers, whose lower expression correlates with worse clinical outcome. We show that higher expression of RETSAT is positively associated with immune infiltration in different human cancers. Furthermore, we identify that the promoter region of RETSAT is highly methylated, which leads to its decreased expressions in tumor tissues comparing to normal tissues. Furthermore, we show that RETSAT knockdown promotes, while its overexpression inhibits, the cell proliferation ability of mouse embryonic fibroblasts (MEFs) and B16 in vitro. In addition, the mice carrying homozygous Q247R mutation (RETSATR/R) is more resistant to xenograft tumor formation, as well as DMBA/TPA induced cutaneous keratinocyte carcinoma formation, compared to littermate wild-type (RETSATQ/Q) mice. Mechanistic study uncovers that the oncogenic factor, the prolyl isomerase (PPIase) Pin1 and its related downstream signaling pathway, were both markedly repressed in the mutant mice compared to the wild-type mice. In summary, these results suggest that interdisciplinary study between evolution and tumor biology can facilitate identification of novel molecular events essential for hypoxic solid tumor growth in the future.

All-Trans Retinoic Acid and Doxorubicin Delivery by Folic Acid Modified Polymeric Micelles for the Modulation of Pin1-Mediated DOX-Induced Breast Cancer Stemness and Metastasis

Stemness and metastasis are the two main challenges in cancer therapy and are related to disease relapse post-treatment. They both have a strong correlation with chemoresistance and poor prognosis, ultimately leading to treatment failure. It has been reported that chemotherapy can induce stemness and metastasis in many cancer types, especially treatment with the chemotherapeutic agent doxorubicin (DOX) in breast cancer. A combination treatment is an efficient and elegant approach in cancer therapy through simultaneous delivery of two or more drugs with a delivery system for its synergistic effect, which is not an additive of two individual drugs. Herein, we report a combinatorial system with DOX and all-trans retinoic acid (ATRA) to address both of the above issues. As a common critical regulatory factor for oncogenic signal transduction pathways, Pin1 is a specific isomerase highly expressed within various tumor cells. ATRA, a newly identified Pin1 inhibitor, can abolish several oncogenic pathways by effectively inhibiting and degrading overexpressed Pin1. We successfully developed a folic acid (FA)-modified chitosan (CSO)-derived polymer (FA-CSOSA) and obtained FA-CSOSA/DOX and FA-CSOSA/ATRA drug-loaded micelles. FA modification can improve the uptake of the nanoparticles in tumor cells and tumor sites via folate receptor-mediated cell internalization. Compared to treatment with DOX alone, the combined treatment induced 4T1 cell apoptosis in a synergistic manner. Reduced stemness-related protein expression and inhibited metastasis were observed during treatment with FA-CSOSA/DOX and FA-CSOSA/ATRA and were found to be associated with Pin1. Further in vivo experiments showed that treatment with FA-CSOSA/DOX and FA-CSOSA/ATRA resulted in 85.5% tumor inhibition, which was 2.5-fold greater than that of cells treated with DOX·HCl alone. This work presents a new paradigm for addressing chemotherapy-induced side effects via degradation of Pin1 induced by tumor-targeted delivery of DOX and ATRA.

Synthesis and analysis of small molecules to restrain the function of tissue factor within tumour cells

Introduction: The restriction of prolyl-protein cis/trans isomerase 1 (Pin1) activity has been shown to prevent the release of tissue factor (TF) leading to the accumulation of the latter protein within the cell. This study tested the ability of novel small molecules to inhibit Pin1, suppress TF activity and release, and induce cellular apoptosis. Methods: Four compounds were designed and synthesised based on modification of 5-(p-methoxyphenyl)-2-methylfuran-3-carbonyl amide and the outcome on MDA-MB-231 and primary cells examined. These compounds contained 3-(2-naphthyl)-_D-alanine (4a), _D-tryptophan (4b), _D-phenylalanine (4c), and _D-tyrosine (4d) at the amino-termini. Results: Treatment of cells with compound 4b and 4d reduced the cell-surface TF activity after 60 min on MDA-MB-231 cells. Incubation with compound 4d also reduced TF antigen on the cell surface and its incorporation into microvesicles, while compounds 4a and 4b significantly increased TF release. None of the four compounds significantly altered the total amount of TF antigen or TF mRNA expression. Compound 4b and 4d also suppressed the binding of Pin1 to TF-cytoplasmic domain peptide. However, compound 4d reduced while compound 4b increased the Pin1 isomerase activity. Finally, treatment with compound 4b and 4d reduced the cell numbers, increased nuclear localisation of p53, Bax protein and bax mRNA expression and induced cellular apoptosis in MDA-MB-231 but not primary endothelial cells. Conclusions: In conclusion, we have identified small molecules to regulate the function of TF within cells. Two of these compounds may prove to be beneficial in moderating TF function specifically and restrain TF-mediated tumour growth without detrimental outcomes on normal vascular cells.

Pathologic role of peptidyl-prolyl isomerase Pin1 in pulmonary artery remodeling

Peptidyl-prolyl isomerase Pin1 is crucial for cell proliferation, but its role in pulmonary artery remodeling (PAR) is unclear. In the present study, we aimed to evaluate the expression and contribution of Pin1 in PAR. Treatment with Pin1 inhibitor Juglone or Pin1-specific siRNAs ameliorated the expression of Pin1 and proliferating cell nuclear antigen (PCNA) in human pulmonary artery smooth muscle cells (PASMCs) in vitro, and Juglone treatment arrested the cell cycle at the G1 phase. Treatment with transforming growth factor β1 (TGF-β1) also enhanced Pin1 expression and PASMC proliferation. Immunohistochemical staining revealed that Pin1 and PCNA expression levels were increased and positively correlated with each other in PAR samples from humans and monocrotaline-treated Sprague-Dawley rats; these proteins were mainly localized in arteries undergoing remodeling, as well as inflammatory cells, and hyperplastic bronchial epithelial cells. Intraperitoneal injection of Juglone also led to morphologic and hemodynamic changes in PAR rats. Additionally, PAR rats displayed higher serum and lung TGF-β1 levels compared with controls, while administration of Juglone to PAR rats suppressed serum and lung TGF-β1 levels. The findings in this study suggest that TGF-β1 and Pin1 constitute a positive feedback loop, which plays an important role in the pathophysiology of PAR.

Cobalt induces neurodegenerative damages through Pin1 inactivation in mice and human neuroglioma cells

Cobalt is a hazardous material that has harmful effects on neurotoxicity. Excessive exposure to cobalt or inactivation of the unique proline isomerase Pin1 contributes to age-dependent neurodegeneration. However, nothing is known about the role of Pin1 in cobalt-induced neurodegeneration. Here we find that out of several hazardous materials, only cobalt dose-dependently decreased Pin1 expression and alterations in its substrates, including cis and trans phosphorylated Tau in human neuronal cells, concomitant with neurotoxicity. Cobalt-induced neurotoxicity was aggravated by Pin1 genetic or chemical inhibition, but rescued by Pin1 upregulation. Furthermore, less than 4 μg/l of blood cobalt induced dose- and age-dependent Pin1 downregulation in murine brains, ensuing neurodegenerative changes. These defects were corroborated by changes in Pin1 substrates, including cis and trans phosphorylated Tau, amyloid precursor protein, β amyloid and GSK3β. Moreover, blood Pin1 was downregulated in human hip replacement patients with median blood cobalt level of 2.514 μg/l, which is significantly less than the safety threshold of 10 μg/l, suggesting an early role Pin1 played in neurodegenerative damages. Thus, Pin1 inactivation by cobalt contributes to age-dependent neurodegeneration, revealing that cobalt is a hazardous material triggering AD-like neurodegenerative damages.

Spectroscopic and computational studies on the binding interaction between gallic acid and Pin1

Gallic acid (GA) is a natural ingredient in functional foods, which has various health-promoting and antitumour effects. Peptidyl-prolyl cis/trans isomerase Pin1 plays an important role in preventing the development of some malignant tumours. However, whether there was an interaction between Pin1 and GA remains unknown. In this work, the binding information of GA and Pin1 was investigated systematically using multiple spectral and computational methods. GA bound to Pin1 directly with moderate binding affinity in the order of 10⁴  mol/L, therefore decreasing the activity of Pin1. Also, the binding process of GA to Pin1 was driven through weak van der Waals forces, hydrogen bonds, and electrostatic forces. In addition, the important residues Lys63, Arg68, and Arg69 played a significant role in maintaining the binding stability between Pin1 and GA. Interestingly, GA reduced the activity of Pin1 by affecting its conformational characteristics. Our present work showed that GA binds to Pin1 and inhibits its activity, affecting its structural and functional properties, which may contribute to the therapy of Pin1-related diseases.

Targeting Pin1 renders pancreatic cancer eradicable by synergizing with immunochemotherapy

Pancreatic ductal adenocarcinoma (PDAC) is characterized by notorious resistance to current therapies attributed to inherent tumor heterogeneity and highly desmoplastic and immunosuppressive tumor microenvironment (TME). Unique proline isomerase Pin1 regulates multiple cancer pathways, but its role in the TME and cancer immunotherapy is unknown. Here, we find that Pin1 is overexpressed both in cancer cells and cancer-associated fibroblasts (CAFs) and correlates with poor survival in PDAC patients. Targeting Pin1 using clinically available drugs induces complete elimination or sustained remissions of aggressive PDAC by synergizing with anti-PD-1 and gemcitabine in diverse model systems. Mechanistically, Pin1 drives the desmoplastic and immunosuppressive TME by acting on CAFs and induces lysosomal degradation of the PD-1 ligand PD-L1 and the gemcitabine transporter ENT1 in cancer cells, besides activating multiple cancer pathways. Thus, Pin1 inhibition simultaneously blocks multiple cancer pathways, disrupts the desmoplastic and immunosuppressive TME, and upregulates PD-L1 and ENT1, rendering PDAC eradicable by immunochemotherapy.

Prolyl-Isomerase Pin1 Controls Key fMLP-Induced Neutrophil Functions

Neutrophils are key cells of the innate immune and inflammatory responses. They are the first blood cells to migrate to the infection site where they release high amounts of reactive oxygen species (ROS) and several peptides and enzymes required for microbial killing. However, excessive neutrophil activation can induce tissue injury participating in inflammation, thus the characterization of the enzymes involved in neutrophil activation could help to identify new pharmacological targets to treat inflammation. The prolyl-isomerase Pin1 is a ubiquitous enzyme involved in several functions, however, its role in neutrophil functions is less known. In this study, we show that the bacterial peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP or fMLF), a G-protein coupled receptor (GPCR) agonist-induced Pin1 activation in human neutrophils. PiB and juglone, two Pin1 inhibitors inhibited Pin1 activity in neutrophils and consequently inhibited fMLP-induced chemotaxis and -degranulation of azurophil and specific granules as measured by myeloperoxidase and neutrophil gelatinase-associated lipocalin (NGAL) release respectively. We also showed that PiB inhibited TNFα + fMLP-induced superoxide production, confirming the effect of juglone. These data show that inhibitors of Pin1 impaired key pro-inflammatory neutrophil functions elicited by GPCR activation and suggest that Pin1 could control neutrophil inflammatory functions.

Distinct phosphorylation profiles of tau in brains of patients with different tauopathies

Tauopathies are neurodegenerative diseases that are characterized by pathological accumulation of tau protein. Tau is hyperphosphorylated in the brain of tauopathy patients, and this phosphorylation is proposed to play a role in disease development. However, it has been unclear whether phosphorylation is different among different tauopathies. Here, we investigated the phosphorylation states of tau in several tauopathies, including corticobasal degeneration, Pick's disease, progressive supranuclear palsy (PSP), argyrophilic grain dementia (AGD) and Alzheimer's disease (AD). Analysis of tau phosphorylation profiles using Phos-tag SDS-PAGE revealed distinct phosphorylation of tau in different tauopathies, whereas similar phosphorylation patterns were found within the same tauopathy. For PSP, we found 2 distinct phosphorylation patterns suggesting that PSP may consist of 2 different related diseases. Immunoblotting with anti-phospho-specific antibodies showed different site-specific phosphorylation in the temporal lobes of patients with different tauopathies. AD brains showed increased phosphorylation at Ser202, Thr231 and Ser235, Pick's disease brains showed increased phospho-Ser202, and AGD brains showed increased phospho-Ser396. The cis conformation of the peptide bond between phospho-Thr231 and Pro232 (cis ptau) was increased in AD and AGD. These results indicate that while tau is differently phosphorylated in tauopathies, a similar pathological mechanism may occur in AGD and AD patients. The present data provide useful information regarding tau pathology and diagnosis of tauopathies.

BAFF signaling drives interstitial transformation of mouse renal tubular epithelial cells in a Pin1-dependent manner

Aberrant expression of B cell–activating factor belonging to TNF superfamily (BAFF) and its receptors results in abnormal biological activities in hematopoietic and non-hematopoietic cells and is closely associated with the occurrence and development of various diseases. However, the biological significance and potential mechanisms underlying BAFF signaling in renal tubular epithelial cells (RTECs) remain unknown. This study aimed to investigate the biological role of BAFF signaling in RTECs. Mice primary RTECs were applied. The proliferation status and apoptotic rates were examined by MTS assay and flow cytometry, respectively. The expression of BAFF and its receptors was analyzed via flow cytometry and sodium ion transport function, and cytokeratin-18 expression was detected through immunofluorescence staining. In addition, Pin1 was knocked down via siRNA and its expression was assessed through reverse transcription PCR. Lastly, western blotting was performed to analyze E-cadherin, ɑ-SMA, and Pin1 expression. Results suggested that BAFF-R was significantly upregulated upon IFN-γ stimulation, and enhancement of BAFF signaling promoted cell survival and reduced their apoptotic rate, while simultaneously reducing the epithelial phenotype and promoting the interstitial transformation of cells. Furthermore, Pin1 was significantly increased, along with the upregulation of BAFF signaling in the RTECs, and participated in interstitial transformation induced by BAFF signaling. Collectively, the present results elucidate the potential mechanism of loss of normal function of RTECs under long-term high dose of BAFF stimulation provides a potential therapeutic target for renal interstitial fibrosis, and underlining mechanisms of shortening of long-term outcomes of kidney allografts via augmenting of BAFF signaling.

Pathological Role of Pin1 in the Development of DSS-Induced Colitis

Inflammatory bowel diseases (IBDs) are serious disorders of which the etiologies are not, as yet, fully understood. In this study, Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) protein was shown to be dramatically upregulated in the colons of dextran sodium sulfate (DSS)-induced ulcerative colitis model mice. Interestingly, Pin1 knockout (KO) mice exhibited significant attenuation of DSS-induced colitis compared to wild-type (WT) mice, based on various parameters, including body weight, colon length, microscopic observation of the intestinal mucosa, inflammatory cytokine expression, and cleaved caspase-3. In addition, a role of Pin1 in inflammation was suggested because the percentage of M1-type macrophages in the colon was decreased in the Pin1 KO mice while that of M2-type macrophages was increased. Moreover, Pin1 KO mice showed downregulation of both Il17 and Il23a expression in the colon, both of which have been implicated in the development of colitis. Finally, oral administration of Pin1 inhibitor partially but significantly prevented DSS-induced colitis in mice, raising the possibility of Pin1 inhibitors serving as therapeutic agents for IBD.

The Pin1-CaMKII-AMPA Receptor Axis Regulates Epileptic Susceptibility

Pin1 is a unique isomerase that regulates protein conformation and function after phosphorylation. Pin1 aberration contributes to some neurological diseases, notably Alzheimer's disease, but its role in epilepsy is not fully understood. We found that Pin1-deficient mice had significantly increased seizure susceptibility in multiple chemical inducing models and developed age-dependent spontaneous epilepsy. Electrophysiologically, Pin1 ablation enhanced excitatory synaptic transmission to prefrontal cortex (PFC) pyramidal neurons without affecting their intrinsic excitability. Biochemically, Pin1 ablation upregulated AMPA receptors and GluA1 phosphorylation by acting on phosphorylated CaMKII. Clinically, Pin1 was decreased significantly, whereas phosphorylated CaMKII and GluA1 were increased in the neocortex of patients with epilepsy. Moreover, Pin1 expression restoration in the PFC of Pin1-deficient mice using viral gene transfer significantly reduced phosphorylated CaMKII and GluA1 and effectively suppressed their seizure susceptibility. Thus, Pin1-CaMKII-AMPA receptors are a novel axis controlling epileptic susceptibility, highlighting attractive new therapeutic strategies.

Inhibition of death-associated protein kinase 1 attenuates cis P-tau and neurodegeneration in traumatic brain injury

Traumatic brain injury (TBI) is the leading cause of mortality and disability in young people and may lead to the development of progressive neurodegeneration, such as that observed in chronic traumatic encephalopathy. We have recently found that the conformation-specific cis phosphorylated form of tau (cis P-tau) is a major early driver of neurodegeneration after TBI. However, not much is known about how cis P-tau is regulated in TBI. In this study, we demonstrated a novel critical role of death-associated protein kinase 1 (DAPK1) in regulating cis P-tau induction after TBI. We found that DAPK1 is significantly upregulated in mouse brains after TBI and subsequently promotes cis P-tau induction. Genetic deletion of DAPK1 in mice not only significantly decreases cis P-tau expression, but also effectively attenuates neuropathology development and rescues behavioral impairments after TBI. Mechanistically, DAPK1-mediated cis P-tau induction is regulated by the phosphorylation of Pin1 at Ser71, a unique prolyl isomerase known to control the conformational status of P-tau. Furthermore, pharmacological suppression of DAPK1 kinase activity dramatically decreases the levels of Pin1 phosphorylated at Ser71 as well as cis P-tau after neuronal stress. Thus, DAPK1 is a novel regulator of TBI that, in combination with its downstream targets, has a major impact on the development and/or outcome of TBI, and targeting DAPK1 might offer a potential therapeutic impact on TBI-related neurodegenerative diseases.

Protein sumoylation with SUMO1 promoted by Pin1 in glioma stem cells augments glioblastoma malignancy

BACKGROUND

The tumorigenic potential of glioma stem cells (GSCs) is associated with multiple reversible molecular alternations, but the role of posttranslational protein sumoylation in GSCs has not been elucidated. The development of GSC-targeting drugs relies on the discovery of GSC-preferential molecular modifications and the relevant signaling pathways. In this work, we investigated the protein sumoylation status, the major sumoylated substrate, and the key regulatory enzyme in GSCs to explore the therapeutic potential of disrupting protein sumoylation for glioblastoma (GBM) treatment.

METHODS

Patient-derived GSCs, primary GBM sections, and intracranial GBM xenografts were used to determine protein sumoylation and the related molecular mechanisms by immunoblot, quantitative PCR, immunoprecipitation, immunofluorescence, and immunohistochemistry. Orthotopic GBM xenograft models were applied to investigate the inhibition of tumor growth by disrupting protein sumoylation with short hairpin (sh)RNAs or molecular inhibitors.

RESULTS

We show that high levels of small ubiquitin-related modifier 1 (SUMO1)-but not SUMO2/3-modified sumoylation are preferentially present in GSCs. The promyelocytic leukemia (PML) protein is a major SUMO1-sumoylated substrate in GSCs, whose sumoylation facilitates its interaction with c-Myc to stabilize c-Myc proteins. The prolyl-isomerase Pin1 is preferentially expressed in GSCs and functions as the key enzyme to promote SUMO1 sumoylation. Disruption of SUMO1 sumoylation by Pin1 silencing with shRNAs or inhibition with its inhibitor Juglone markedly abrogated GSC maintenance and mitigated GSC-driven tumor growth.

CONCLUSIONS

Our findings indicate that high SUMO1-modified protein sumoylation as a feature of GSCs is critical for GSC maintenance, suggesting that targeting SUMO1 sumoylation may effectively improve GBM treatment.

Targeting Pin1 for Modulation of Cell Motility and Cancer Therapy

Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) specifically binds and isomerizes the phosphorylated serine/threonine-proline (pSer/Thr-Pro) motif, which leads to changes in protein conformation and function. Pin1 is widely overexpressed in cancers and plays an important role in tumorigenesis. Mounting evidence has revealed that targeting Pin1 is a potential therapeutic approach for various cancers by inhibiting cell proliferation, reducing metastasis, and maintaining genome stability. In this review, we summarize the underlying mechanisms of Pin1-mediated upregulation of oncogenes and downregulation of tumor suppressors in cancer development. Furthermore, we also discuss the multiple roles of Pin1 in cancer hallmarks and examine Pin1 as a desirable pharmaceutical target for cancer therapy. We also summarize the recent progress of Pin1-targeted small-molecule compounds for anticancer activity.

Promoter Methylation and Gene Expression of Pin1 Associated with the Risk of Alzheimer's Disease in Southern Chinese

BACKGROUND

Pin1 is a propyl cis-trans isomerase and it has been associated with age-atonset of Alzheimer's disease (AD) and other pathological characteristics of AD. DNA methylation is one of the gene regulation mechanisms and it might affect the gene expression.

OBJECTIVE

This study was aimed to examine the correlation between DNA methylation and gene expression of Pin1 and its effect on the risk of AD in a Chinese population.

METHODS

80 AD patients and 180 normal controls were recruited in this study and their cognitive functions were assessed. Pin1 gene expression and methylation were quantified by real-time RT-PCR and Melting Curve Analysis-Methylation assay (MCA-Meth), respectively.

RESULTS

Our finding revealed a positive correlation between methylation and gene expression of Pin1 (p=0.001) and increased Pin1 methylation was predisposed to the risk of AD (p<0.001). CG genotype of Pin1 SNP rs2287839 was associated with higher gene expression of Pin1 (p=0.036) and the effect was only prominent in normal controls as AD patients were already methylated at Pin1 promoter. Furthermore, methylation of Pin1 was associated with better performance in cognition (p=0.018).

CONCLUSION

Our result further supported the involvement of Pin1 in AD and the increased level of Pin1 might be a protective factor for AD.

Pin1 Promotes NLRP3 Inflammasome Activation by Phosphorylation of p38 MAPK Pathway in Septic Shock

Pin1 is the only known peptidyl-prolyl cis-trans isomerase (PPIase) that can specifically recognize and isomerize the phosphorylated Serine/Threonine-Proline (pSer/Thr-Pro) motif, change the conformation of proteins through protein phosphorylation, thus regulate various cellular processes in the body. Pin1 plays an important role in cancer, Alzheimer’s disease, and autoimmune diseases. However, the specific mechanism of Pin1 regulation in LPS-induced septic shock is unclear. Here, we found that lack of Pin1 reduced shock mortality and organ damage in mice, and NLRP3 inflammasome activation also was reduced in this process. We further confirmed that Pin1 can affect the expression of NLRP3, ASC, Caspase1, and this process can be regulated through the p38 MAPK pathway. We analyzed that p38 MAPK signaling pathway was highly expressed in septic shock and showed a positive correlation with Pin1 in the Gene Expression Omnibus database. We found that Pin1 could affect the phosphorylation of p38 MAPK, have no obvious difference in extracellular signal-regulated kinases (ERK) and Jun-amino-terminal kinase (JNK) signaling. We further found that Pin1 and p-p38 MAPK interacted, but not directly. In addition, Pin1 deficiency inhibited the cleavage of gasdermin D (GSDMD) and promoted the death of macrophages with LPS treatment, and reduced secretion of inflammatory cytokines including IL-1β and IL-18. In general, our results suggest that Pin1 regulates the NLRP3 inflammasome activation by p38 MAPK signaling pathway in macrophages. Thus, Pin1 may be a potential target for the treatment of inflammatory diseases such as septic shock.

Pin1 and JNK1 cooperatively modulate TAp63γ

The p63 gene encodes at least 10 isoforms, which can be classified into TA and ∆N isotypes (TAp63 and ∆Np63 proteins) according to their differences at the N termini. TAp63γ is an important transcription factor. We previously reported that peptidyl‐prolyl isomerase (PPI) Pin1 directly binds to TAp63γ protein and identified that serine 12 (S₁₂) in the transactivation domain (TAD) of TAp63γ is required for regulation of its transcriptional activity. In the present study, we report that Pin1 stimulates transcriptional and pro‐apoptotic activities of TAp63γ; this Pin1‐mediated stimulation may depend on phosphorylation of S₁₂ mediated by JNK1 and results in striking activation of TAp63γ. JNK1 represses transactivity of TAp63γ in cells without abundant Pin1 proteins and enhances it in the presence of sufficient levels of Pin1. Collectively, our data suggest a novel mechanism for regulation of TAp63γ transactivity: TAp63γ with unphosphorylated S₁₂ is moderately active, phosphorylation at this residue (pS₁₂) makes it hypoactive, and Pin1 binds to the pS₁₂‐P₁₃ motif and makes TAp63γ hyperactive. Our findings will aid in the elucidation of the mechanism underlying modulation of TAp63γ.

Pin1 Regulates IL-5 Induced Eosinophil Polarization and Migration

Eosinophils become polarized in response to cytokines such IL-5 or eotaxin prior to directional migration. Polarization is preceded by F-actin assembly, but the mechanisms that regulate these events and how the shape change influences cell migration from the peripheral blood into the lung remain unclear. In this study, we show that the prolyl isomerase, Pin1, is required for IL-5-induced Eos polarization and migration. Co-immunoprecipitation and immunofluorescence analysis revealed that Pin1 directly interacts with members of Rho GTPase family. Mouse eosinophils lacking Pin1 or human cells treated with Pin1 inhibitors showed significantly reduced IL-5-induced GTPase activity and cofilin phosphorylation, resulting in reduced F-actin polymerization, cell polarization, and directional migration to chemokines. Our result suggests that Pin1 regulates cytoskeletal re-organization, eosinophil morphology, and cell migration through the modulation of Rho GTPase activity. Targeting Pin1 along with GTPases could provide a new approach to reduce pulmonary Eos accumulation during asthmatic exacerbations.

Roles of peptidyl-prolyl isomerase Pin1 in disease pathogenesis

Pin1 belongs to the peptidyl-prolyl cis-trans isomerases (PPIases) superfamily and catalyzes the cis-trans conversion of proline in target substrates to modulate diverse cellular functions including cell cycle progression, cell motility, and apoptosis. Dysregulation of Pin1 has wide-ranging influences on the fate of cells; therefore, it is closely related to the occurrence and development of various diseases. This review summarizes the current knowledge of Pin1 in disease pathogenesis.