The prolyl isomerase PIN1: a pivotal new twist in phosphorylation signalling and disease

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.

Synthesis and Conformational Analysis of N-Aromatic Acetamides Bearing Thiophene: Effect of Intramolecular Chalcogen-Chalcogen Interaction on Amide Conformational Stability

The conformations of aromatic amides bearing an N-(2-thienyl) or N-(3-thienyl) group were investigated in solution and in the crystal state. NMR spectral data indicate that the conformational preferences of these amides in solution are dependent not only on the relative π-electron densities of the N-aromatic moieties, but also on the three-dimensional relationship between carbonyl oxygen and the N-aromatic moieties. A comparison of the conformational preferences of N-(2-thienyl)amides and N-(3-thienyl)amides revealed that the Z-conformers of N-(2-thienyl)acetamides are stabilized by 1,5-type intramolecular S···O═C interactions between amide carbonyl and thiophene sulfur. The crystal structures of these compounds were similar to the solution structures. The stabilization energy due to 1,5-type intramolecular S···O═C interaction in N-aryl-N-(2-thienyl)acetamides and N-methyl-N-(2-thienyl)acetamide was estimated to be ca. 0.74 and 0.93 kcal/mol, respectively.

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.

PIN1 and CDK1 cooperatively govern pVHL stability and suppressive functions

The VHL protein (pVHL) functions as a tumor suppressor by regulating the degradation or activation of protein substrates such as HIF1α and Akt. In human cancers harboring wild-type VHL, the aberrant downregulation of pVHL is frequently detected and critically contributes to tumor progression. However, the underlying mechanism by which the stability of pVHL is deregulated in these cancers remains elusive. Here, we identify cyclin-dependent kinase 1 (CDK1) and peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (PIN1) as two previously uncharacterized regulators of pVHL in multiple types of human cancers harboring wild-type VHL including triple-negative breast cancer (TNBC). PIN1 and CDK1 cooperatively modulate the protein turnover of pVHL, thereby conferring tumor growth, chemotherapeutic resistance and metastasis both in vitro and in vivo. Mechanistically, CDK1 directly phosphorylates pVHL at Ser80, which primes the recognition of pVHL by PIN1. PIN1 then binds to phosphorylated pVHL and facilitates the recruitment of the E3 ligase WSB1, therefore targeting pVHL for ubiquitination and degradation. Furthermore, the genetic ablation or pharmacological inhibition of CDK1 by RO-3306 and PIN1 by all-trans retinoic acid (ATRA), the standard care for Acute Promyelocytic Leukemia could markedly suppress tumor growth, metastasis and sensitize cancer cells to chemotherapeutic drugs in a pVHL dependent manner. The histological analyses show that PIN1 and CDK1 are highly expressed in TNBC samples, which negatively correlate with the expression of pVHL. Taken together, our findings reveal the previous unrecognized tumor-promoting function of CDK1/PIN1 axis through destabilizing pVHL and provide the preclinical evidence that targeting CDK1/PIN1 is an appealing strategy in the treatment of multiple cancers with wild-type VHL.

Pin1 and Alzheimer's disease

Alzheimer's disease (AD) is an immense and growing public health crisis. Despite over 100 years of investigation, the etiology remains elusive and therapy ineffective. Despite current gaps in knowledge, recent studies have identified dysfunction or loss-of-function of Pin1, a unique cis-trans peptidyl prolyl isomerase, as an important step in AD pathogenesis. Here I review the functionality of Pin1 and its role in neurodegeneration.

Small molecules targeting Pin1 as potent anticancer drugs

Background: Pin1 is a member of the evolutionarily conserved peptidyl-prolyl isomerase (PPIase) family of proteins. Following phosphorylation, Pin1-catalyzed prolyl-isomerization induces conformational changes, which serve to regulate the function of many phosphorylated proteins that play important roles during oncogenesis. Thus, the inhibition of Pin1 provides a unique means of disrupting oncogenic pathways and therefore represents an appealing target for novel anticancer therapies.

Methods: As Pin1 is conserved between yeast and humans, we employed budding yeast to establish a high-throughput screening method for the primary screening of Pin1 inhibitors. This effort culminated in the identification of the compounds HWH8-33 and HWH8-36. Multifaceted approaches were taken to determine the inhibition profiles of these compounds against Pin1 activity in vitro and in vivo, including an isomerization assay, surface plasmon resonance (SPR) technology, virtual docking, MTT proliferation assay, western blotting, cell cycle analysis, apoptosis analysis, immunofluorescence analysis, wound healing, migration assay, and nude mouse assay.

Results:In vitro, HWH8-33 and HWH8-36 could bind to purified Pin1 and inhibited its enzyme activity; showed inhibitory effects on cancer cell proliferation; led to G2/M phase arrest, dysregulated downstream protein expression, and apoptosis; and suppressed cancer cell migration. In vivo, HWH8-33 suppressed tumor growth in the xenograft mice after oral administration for 4 weeks, with no noticeable toxicity. Together, these results show the anticancer activity of HWH8-33 and HWH8-36 against Pin1 for the first time.

Conclusion: In summary, we identified two hit compounds HWH8-33 and HWH8-36, which after further structure optimization have the potential to be developed as antitumor drugs.

Cinobufacini injection suppresses the proliferation of human osteosarcoma cells by inhibiting PIN1-YAP/TAZ signaling pathway

Cinobufacini injection (CI), an aqueous extract of Cutis Bufonis, is clinically used for cancer therapy in China, but its molecular mechanism for the treatment of osteosarcoma (OS) remains unclear. We constructed U2OS ectopic subcutaneous tumor model to verify the anti-OS effect of CI in vivo. Meanwhile, cell proliferation of U2OS and MG63 cells was monitored in vitro using the CCK-8 assay, colony formation and morphological changes. Cell cycle arrest and apoptosis were detected by flow cytometry and western blot, which showed that CI significantly inhibited proliferation, induced cell cycle arrest and apoptosis in human OS cells. The further RNA-seq results identified that the Hippo signaling pathway was involved in the anti-OS effect of CI. YAP/TAZ are two major components of the Hippo pathway in breast cancer and are positively regulated by prolyl isomerase PIN1, we assessed their role in OS using both clinicopathological sections and western blots. CI also inhibited PIN1 enzyme activity in a dose-dependent manner, which resulted in impaired PIN1, YAP, and TAZ expression in vitro and in vivo. Additionally, 15 potential compounds of CI were found to occupy the PIN1 kinase domain and inhibit its activity. In summary, CI plays an anti-OS role by down-regulating the PIN1-YAP/TAZ pathway.

Chaperoning of specific tau structure by immunophilin FKBP12 regulates the neuronal resilience to extracellular stress

Alzheimer's disease and related tauopathies are characterized by the pathogenic misfolding and aggregation of the microtubule-associated protein tau. Understanding how endogenous chaperones modulate tau misfolding could guide future therapies. Here, we show that the immunophilin FKBP12, the 12-kDa FK506-binding protein (also known as FKBP prolyl isomerase 1A), regulates the neuronal resilience by chaperoning a specific structure in monomeric tau. Using a combination of mouse and cell experiments, in vitro aggregation experiments, nuclear magnetic resonance-based structural analysis of monomeric tau, site-specific phosphorylation and mutation, as well as structure-based analysis using the neural network-based structure prediction program AlphaFold, we define the molecular factors that govern the binding of FKBP12 to tau and its influence on tau-induced neurotoxicity. We further demonstrate that tyrosine phosphorylation of tau blocks the binding of FKBP12 to two highly specific structural motifs in tau. Our data together with previous results demonstrating FKBP12/tau colocalization in neurons and neurofibrillary tangles support a critical role of FKBP12 in regulating tau pathology.

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.

Regulation of eukaryotic protein kinases by Pin1, a peptidyl-prolyl isomerase

The peptidyl-prolyl isomerase Pin1 cooperates with proline-directed kinases and phosphatases to regulate multiple oncogenic pathways. Pin1 specifically recognizes phosphorylated Ser/Thr-Pro motifs in proteins and catalyzes their cis-trans isomerization. The Pin1-catalyzed conformational changes determine the stability, activity, and subcellular localization of numerous protein substrates. We conducted a survey of eukaryotic protein kinases that are regulated by Pin1 and whose Pin1 binding sites have been identified. Our analyses reveal that Pin1 target sites in kinases do not fall exclusively within the intrinsically disordered regions of these enzymes. Rather, they fall into three groups based on their location: (i) within the catalytic kinase domain, (ii) in the C-terminal kinase region, and (iii) in regulatory domains. Some of the kinases downregulated by Pin1 activity are tumor-suppressing, and all kinases upregulated by Pin1 activity are functionally pro-oncogenic. These findings further reinforce the rationale for developing Pin1-specific inhibitors as attractive pharmaceuticals for cancer therapy.

Par14 interacts with the androgen receptor, augmenting both its transcriptional activity and prostate cancer proliferation

BACKGROUND

Prostate cancer (PCa) is a major cause of cancer morbidity and mortality for men globally, and androgen signaling clearly drives its onset and progression. Androgen receptor (AR) regulation is complex and remains elusive, despite several studies tackling these issues. Therefore, elucidating the mechanism(s) underlying AR regulation is a potentially promising approach to suppressing PCa.

METHODS

We report that Par14, one isoform of the prolyl isomerases homologous to Pin1, is a critical regulator of AR transcriptional activity and is essential for PCa cell growth.

RESULTS

Par14 was shown to be overexpressed in PCa, based on analyses of deposited data. Importantly, overexpression of Par14 significantly enhanced androgen-sensitive LNCap cell growth. In contrast, silencing of Par14 dramatically decreased cell growth in LNCap cells by causing cell cycle arrest. Mechanistically, silencing of the Par14 gene dramatically induced cyclin-dependent kinase inhibitor p21 at both the mRNA and the protein level through modulating the localization of p53. In addition, suppression of Par14 in LNCap cells was shown to downregulate the expressions of androgen response genes, at both the mRNA and the protein level, induced by dihydrotestosterone. Par14 was shown to directly associate with AR in nuclei via its DNA-binding domain and augment AR transcriptional activity.

CONCLUSION

Thus, Par14 plays a critical role in PCa progression, and its enhancing effects on AR signaling are likely to be involved in the underlying molecular mechanisms. These findings suggest Par14 to be a promising therapeutic target for PCa.

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.

The role of peptidyl-prolyl isomerase Pin1 in neuronal signaling in epilepsy

Epilepsy is a common symptom of many neurological disorders and can lead to neuronal damage that plays a major role in seizure-related disability. The peptidyl-prolyl isomerase Pin1 has wide-ranging influences on the occurrence and development of neurological diseases. It has also been suggested that Pin1 acts on epileptic inhibition, and the molecular mechanism has recently been reported. In this review, we primarily focus on research concerning the mechanisms and functions of Pin1 in neurons. In addition, we highlight the significance and potential applications of Pin1 in neuronal diseases, especially epilepsy. We also discuss the molecular mechanisms by which Pin1 controls synapses, ion channels and neuronal signaling pathways to modulate epileptic susceptibility. Since neurotransmitters and some neuronal signaling pathways, such as Notch1 and PI3K/Akt, are vital to the nervous system, the role of Pin1 in epilepsy is discussed in the context of the CaMKII-AMPA receptor axis, PSD-95-NMDA receptor axis, NL2/gephyrin-GABA receptor signaling, and Notch1 and PI3K/Akt pathways. The effect of Pin1 on the progression of epilepsy in animal models is discussed as well. This information will lead to a better understanding of Pin1 signaling pathways in epilepsy and may facilitate development of new therapeutic strategies.

Circulating levels of PIN1 and glucose metabolism in young people with obesity

PURPOSE

Impaired activity of the peptidylprolyl cis/trans isomerase NIMA-interacting 1 (PIN1) isomerase might contribute to link disturbed glucose metabolism and risk of glucose related neurotoxicity, neurodegeneration and cognitive decline. The isomerase modulates also pathways of peripheral insulin sensitivity and secretion. We aimed at investigating the levels of circulating PIN1 in adolescents with obesity and any association with their glucose metabolism.

METHODS

We enrolled 145 adolescents (age 12-17.8 years); 67 lean controls (46.2%) and 78 (53.8%) with overweight or obesity (males n = 62, 46%). We estimated glucose and insulin in fasting condition and after a standard oral glucose tolerance test; fasting serum levels of PIN1, amyloid β-protein 42 (Aβ42), presenilin 1 (PSEN1), glucagon-like peptide 1 (GLP1) and Non Esterified Fatty Acids (NEFA). We calculated the homeostasis model assessment of insulin resistance (HOMA-IR), the β cell function (HOMA-β) and the Adipo-IR.

RESULTS

There was no difference in PIN1 serum levels between normal weight individuals and patients with obesity. However, there was an inverse correlation between serum fasting PIN1 and glucose (r - 0.183 and p = 0.027). We confirmed levels of Aβ42 and PSEN1 were higher in teens with obesity than in lean controls and their correlation with the body mass index (Aβ42: r = 0.302, p = 0.0001, PSEN1 r = 0.231, p = 0.005) and the HOMA-IR (Aβ42: r = 0.219, p = 0.009, r = 0.170, p < 0.042).

CONCLUSIONS

There was no significant rise of circulating PIN1 levels in young individuals with obesity. Increased levels reported in the literature in adult patients are likely to occur late in the natural history of the disease with the onset of an overt impairment of glucose homeostasis.

Kidney Failure Alters Parathyroid Pin1 Phosphorylation and Parathyroid Hormone mRNA-Binding Proteins, Leading to Secondary Hyperparathyroidism

BACKGROUND

Secondary hyperparathyroidism (SHP) is a common complication of CKD that increases morbidity and mortality. In experimental SHP, increased parathyroid hormone (PTH) expression is due to enhanced PTH mRNA stability, mediated by changes in its interaction with stabilizing AUF1 and destabilizing KSRP. The isomerase Pin1 leads to KSRP dephosphorylation, but in SHP parathyroid Pin1 activity is decreased and hence phosphorylated KSRP fails to bind PTH mRNA, resulting in high PTH mRNA stability and levels. The up- and downstream mechanisms by which CKD stimulates the parathyroid glands remain elusive.

METHODS

Adenine-rich high-phosphate diets induced CKD in rats and mice. Parathyroid organ cultures and transfected cells were incubated with Pin1 inhibitors for their effect on PTH expression. Mass spectrometry was performed on both parathyroid and PTH mRNA pulled-down proteins.

RESULTS

CKD led to changes in rat parathyroid proteome and phosphoproteome profiles, including KSRP phosphorylation at Pin1 target sites. Furthermore, both acute and chronic kidney failure led to parathyroid-specific Pin1 Ser16 and Ser71 phosphorylation, which disrupts Pin1 activity. Pharmacologic Pin1 inhibition, which mimics the decreased Pin1 activity in SHP, increased PTH expression ex vivo in parathyroid glands in culture and in transfected cells through the PTH mRNA-protein interaction element and KSRP phosphorylation.

CONCLUSIONS

Kidney failure leads to loss of parathyroid Pin1 activity by inducing Pin1 phosphorylation. This predisposes parathyroids to increase PTH production through impaired PTH mRNA decay that is dependent on KSRP phosphorylation at Pin1-target motifs. Pin1 and KSRP phosphorylation and the Pin1-KSRP-PTH mRNA axis thus drive SHP.

The kingdom of the prolyl-isomerase Pin1: The structural and functional convergence and divergence of Pin1

More than 20 years since its discovery, our understanding of Pin1 function in various diseases continues to improve. Pin1 plays a crucial role in pathogenesis and has been implicated in metabolic disorders, cardiovascular diseases, inflammatory diseases, viral infection, cancer and neurodegenerative diseases such as Alzheimer’s, Parkinson’s and Huntington’s disease. In particular, the role of Pin1 in neurodegenerative diseases and cancer has been extensively studied. Our understanding of Pin1 in cancer also led to the development of cancer therapeutic drugs targeting Pin1, with some currently in clinical trial phases. However, identifying a Pin1-specific drug with good cancer therapeutic effect remains elusive, thus leading to the continued efforts in Pin1 research. The importance of Pin1 is highlighted by the presence of Pin1 orthologs across various species: from vertebrates to invertebrates and Kingdom Animalia to Plantae. Among these Pin1 orthologs, their sequence and structural similarity demonstrate the presence of conservation. Moreover, their similar functionality between species further highlights the conservancy of Pin1. As researchers continue to unlock the mysteries of Pin1 in various diseases, using different Pin1 models might shed light on how to better target Pin1 for disease therapeutics. This review aims to highlight the various Pin1 orthologs in numerous species and their divergent functional roles. We will examine their sequence and structural similarities and discuss their functional similarities and uniqueness to demonstrate the interconnectivity of Pin1 orthologs in multiple diseases.

PIN1-mediated ROS production is involved in antagonism of N-acetyl-L-cysteine against arsenic-induced hepatotoxicity

Arsenic, a widely existing environmental contaminant, is recognized to be toxic to multiple organs. Exposure to arsenic results in liver damage via excessive production of reactive oxidative species (ROS). PIN1 regulates the levels of ROS. N-acetyl-L-cysteine (NAC) is an ROS scavenger that protects the hepatic functions. Whether PIN1 plays a regulatory role in NAC-mediated antagonism against arsenic hepatotoxicity remains largely unknown. In our study, the protective effects of NAC against arsenic (NaAsO2)-induced hepatotoxicity were evaluated in vitro and in vivo. Arsenic exposure induced cytotoxicity by increasing the intracellular ROS production, impairing mitochondrial function and inducing apoptosis in L02 hepatocytes. Overexpression of PIN1 markedly protected against arsenic cytotoxicity, decreased ROS levels, and mitigated mitochondrial dysfunction and apoptosis in L02 cells. However, loss of PIN1 further aggravated arsenic-induced cytotoxicity and abolished the protective effects of NAC in L02 cells. An in vivo study showed that pretreatment with NAC rescued arsenic-induced liver injury by restoring liver function and suppressing hepatic oxidative stress. Overexpression of PIN1 in mice transfected with AAV-Pin1 relieved arsenic-induced liver dysfunction and hepatic oxidative stress. Taken together, our study identified PIN1 as a novel intervention target for antagonizing arsenic-induced hepatotoxicity, highlighting a new pharmacological mechanism of NAC targeting PIN1 in antagonism against arsenic toxicity.

Targeting peptidyl-prolyl isomerase 1 in experimental pulmonary arterial hypertension

BACKGROUND

Pulmonary arterial hypertension (PAH) is a progressive disease characterised by pro-proliferative and anti-apoptotic phenotype in vascular cells, leading to pulmonary vascular remodelling and right heart failure. Peptidyl-prolyl cis/trans isomerase, NIMA interacting 1 (Pin1), a highly conserved enzyme, which binds to and catalyses the isomerisation of specific phosphorylated Ser/Thr-Pro motifs, acts as a molecular switch in multiple coordinated cellular processes. We hypothesised that Pin1 plays a substantial role in PAH, and its inhibition with a natural organic compound, Juglone, would reverse experimental pulmonary hypertension.

RESULTS

We demonstrated that the expression of Pin1 was markedly elevated in experimental pulmonary hypertension (i.e. hypoxia-induced mouse and Sugen/hypoxia-induced rat models) and pulmonary arterial smooth muscle cells of patients with clinical PAH. In vitro Pin1 inhibition by either Juglone treatment or short interfering RNA knockdown resulted in an induction of apoptosis and decrease in proliferation of human pulmonary vascular cells. Stimulation with growth factors induced Pin1 expression, while its inhibition reduced the activity of numerous PAH-related transcription factors, such as hypoxia-inducible factor (HIF)-α and signal transducer and activator of transcription (STAT). Juglone administration lowered pulmonary vascular resistance, enhanced right ventribular function, improved pulmonary vascular and cardiac remodelling in the Sugen/hypoxia rat model of PAH and the chronic hypoxia-induced pulmonary hypertension model in mice.

CONCLUSION

Our study demonstrates that targeting of Pin1 with small molecule inhibitor, Juglone, might be an attractive future therapeutic strategy for PAH and right heart disease secondary to PAH.

Pancreatic tumor eradication via selective Pin1 inhibition in cancer-associated fibroblasts and T lymphocytes engagement

Cancer associated fibroblasts (CAFs) support tumors via multiple mechanisms, including maintaining the immunosuppressive tumor microenvironment and limiting infiltration of immune cells. The prolyl isomerase Pin1, whose overexpression in CAFs has not been fully profiled yet, plays critical roles in tumor initiation and progression. To decipher effects of selective Pin1 inhibition in CAFs on pancreatic cancer, here we formulate a DNA-barcoded micellular system (DMS) encapsulating the Pin1 inhibitor AG17724. DMS functionalized with CAF-targeting anti-FAP-α antibodies (antiCAFs-DMS) can selectively inhibit Pin1 in CAFs, leading to efficacious but transient tumor growth inhibition. We further integrate DNA aptamers (AptT), which can engage CD8+ T lymphocytes, to obtain a bispecific antiCAFs-DMS-AptT system. AntiCAFs-DMS-AptT inhibits tumor growth in subcutaneous and orthotopic pancreatic cancer models.

Pharmacological inhibition of the prolyl isomerase PIN1, highly expressed in cancer cells and cancer associated fibroblasts (CAF), has been proposed for cancer therapy. Here the authors report the design of a DNA-barcoded micellular system functionalized with antibodies targeting CAFs and a T cell recruiting aptamer to deliver the PIN1 inhibitor AG17724, showing antitumor response in preclinical models of pancreatic cancer.

The CD8α hinge is intrinsically disordered with a dynamic exchange that includes proline cis-trans isomerization

T cells engineered to express artificial chimeric antigen receptors (CARs) that selectively target tumor-specific antigens or deleterious cell types offer transformative therapeutic possibilities. CARs contain an N-terminal extracellular antigen recognition domain, C-terminal intracellular signal transduction domains, and connecting hinge and transmembrane regions, each of which have been varied to optimize targeting and minimize toxicity. We find that a CD22-targeting CAR harboring a CD8α hinge (H) exhibits greater cytotoxicity against a low antigen density CD22⁺ leukemia as compared to an equivalent CAR with a CD28 H. We therefore studied the biophysical and dynamic properties of the CD8α H by nuclear magnetic resonance (NMR) spectroscopy. We find that a large region of the CD8α H undergoes dynamic chemical exchange between distinct and observable states. This exchanging region contains proline residues dispersed throughout the sequence that undergo cis-trans isomerization. Up to four signals of differing intensity are observed, with the most abundantly populated being intrinsically disordered and with all prolines in the trans isomerization state. The lesser populated states all contain cis prolines and evidence of local structural motifs. Altogether, our data suggest that the CD8α H lacks long-range structural order but has local structural motifs that transiently exchange with a dominant disordered state. We propose that structural plasticity and local structural motifs promoted by cis proline states within the CD8α H are important for relaying and amplifying antigen-binding effects to the transmembrane and signal transduction domains.

A Specific pSer/Thr-Pro Motif Generates Interdomain Communication Bifurcations of Two Modes of Pin1 in Solution Nuclear Magnetic Resonance

Peptides mediate the interdomain communication of Pin1 (peptidyl-prolyl cis-trans isomerase) and can regulate its conformation and biochemical functions, providing an idea for drug design using Pin1. Two template peptide sequences have been widely used in the extended or compact state of Pin1 (Cdc25C, E-Q-P-L-pT-P-V-T-D-L; Pintide, W-F-Y-pS-P-R). The way in which specific pSer/Thr-Pro peptides regulate interdomain communication to achieve the opposite state is not clear. In this study, we subdivided the sequence composition of eight types of modified peptides and investigated the interaction with Pin1 by solution nuclear magnetic resonance and molecular dynamics. Demonstrating sequence dependence on the pSer-Pro or pThr-Pro motif and different residues in anchoring the WW domain, the Pin peptide (Pintide, PintideT, Pin25C, and Pin25CT) transmits this concentration accumulation to the PPIase domain, thus exhibiting two anchoring tendencies. However, the Cdc peptide (Cdc25C, Cdc25CS, Cdctide, and CdctideS) has a low binding energy that makes it difficult for the conformation to reach a steady state. In addition, Pin1 is influenced by both compact and extended states, regulated precisely by the sequence as well as by threonine or serine. These results provide new insight into the interdomain communication of Pin1 via pSer/Thr-Pro peptide binding.

The Yin and Yang of GABAergic and Glutamatergic Synaptic Plasticity: Opposites in Balance by Crosstalking Mechanisms

Synaptic plasticity is a critical process that regulates neuronal activity by allowing neurons to adjust their synaptic strength in response to changes in activity. Despite the high proximity of excitatory glutamatergic and inhibitory GABAergic postsynaptic zones and their functional integration within dendritic regions, concurrent plasticity has historically been underassessed. Growing evidence for pathological disruptions in the excitation and inhibition (E/I) balance in neurological and neurodevelopmental disorders indicates the need for an improved, more "holistic" understanding of synaptic interplay. There continues to be a long-standing focus on the persistent strengthening of excitation (excitatory long-term potentiation; eLTP) and its role in learning and memory, although the importance of inhibitory long-term potentiation (iLTP) and depression (iLTD) has become increasingly apparent. Emerging evidence further points to a dynamic dialogue between excitatory and inhibitory synapses, but much remains to be understood regarding the mechanisms and extent of this exchange. In this mini-review, we explore the role calcium signaling and synaptic crosstalk play in regulating postsynaptic plasticity and neuronal excitability. We examine current knowledge on GABAergic and glutamatergic synapse responses to perturbances in activity, with a focus on postsynaptic plasticity induced by short-term pharmacological treatments which act to either enhance or reduce neuronal excitability via ionotropic receptor regulation in neuronal culture. To delve deeper into potential mechanisms of synaptic crosstalk, we discuss the influence of synaptic activity on key regulatory proteins, including kinases, phosphatases, and synaptic structural/scaffolding proteins. Finally, we briefly suggest avenues for future research to better understand the crosstalk between glutamatergic and GABAergic synapses.

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.

Neurodegenerative effect of DAPK1 after cerebral hypoxia-ischemia is associated with its post-transcriptional and signal transduction regulations: A systematic review and meta-analysis

Cerebral hypoxia-ischemia (CHI) causes brain aging, neurological disorders, cognitive decline, motor function impairment, and mortality. Inhibiting death-associated protein kinase 1 (DAPK1) has shown therapeutic potential against CHI, but several reports contradict its protective function, mechanism of activation, and signal transduction. Here, we systematically reviewed the role and the activation mechanism of DAPK1, and quantitatively assess the efficacy of DAPK1 inhibition (DI) methods in neuroprotection, following a CHI in animal models. Embase and PubMed were searched for relevant studies. Overall, 13 studies met the inclusion criteria, and the SYRCLE Risk of bias tool (RoB) tool was used to assess RoB. StataSE 16 was used for meta-analysis and network meta-analysis (NMA). Standardized mean differences (SMD) with 95% confidence intervals (CI) were calculated to estimate the effect size. DI was associated with the reduction of brain infarct volume (BIV) [SMD = -1.70, 95% CI (-2.10, -1.30); p = 0.00], neurological score (N.S.), neuronal degeneration, with no change in the level of in cell death [SMD = -0.83, 95% CI (-2.00, 0.35); p = 0.17], indicating the protective role of DI against CHI. No differences were found in DAPK1 mRNA and protein levels [SMD = 0.50, 95% CI (-0.05, 1.04); p = 0.07] {single-study driven; upregulated after exclusion (p = 0.01, I² = 36.43)}, whereas phospho-DAPK1 [SMD = -2.22, 95% CI (-3.69, -0.75); p = 0.00] was downregulated and phosphorylated myosin light chain [SMD = 3.37, 95% CI (2.51, 4.96); p = 0.00] was upregulated between CHI and sham groups. Furthermore, we performed NMA to understand the molecular level at which DI offers maximum protection against BIV. Post-transcriptional inhibition (PTI; SUCRA, 82.6%) and gene knockout showed best (KO; SUCRA, 81.3%), signal transduction inhibition (STI; SUCRA, 49.5%) offered 3^rd best, while catalytic activity inhibition (CAI; SUCRA, 0.3%) exhibited the lowest reduction in BIV against CHI. The results demonstrate that DI has a neuroprotective effect against CHI and DAPK1 might be regulated at the post-transcriptional and post-translational levels after CHI. Inhibiting DAPK1 at the post-transcriptional level and blocking multiple signal transduction pathways of DAPK1 could lead to better functional recovery against CHI. AVAILABILITY OF DATA AND MATERIALS: The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Molecular biological mechanism of action in cancer therapies: Juglone and its derivatives, the future of development

Juglone (5 - hydroxy - 1, 4 - naphthalene diketone) is a kind of natural naphthoquinone, present in the roots, leaves, nut-hulls, bark and wood of walnut trees. Recent studies have found that Juglone has special significance in the treatment of cancer, which plays a significant role in the resistance of cancer cell proliferation, induction of cancer cell apoptosis, induction of autophagy, anti-angiogenesis and inhibition of cancer cell migration and invasion, etc. Additionally, its derivatives also play a tumor suppressive effect. In conclusion, Juglone and its derivatives have been identified as effective anticancer drugs. This paper reviews action mechanisms of Juglone and its derivatives in cancer treatment.

Design and Synthesis of New Oligopeptidic Parvulin Inhibitors

Pin1 catalyzes the cis-trans isomerization of pThr-Pro or pSer-Pro amide bonds of different proteins involved in several physio/pathological processes. In this framework, recent research activity is directed towards the identification of new selective Pin1 inhibitors. Here, we developed a set ( 5a - p ) of peptide-based Pin1 inhibitors. Direct-binding experiments allowed the identification of the peptide-based inhibitor 5k as a potent ligand of Pin1. Notably, 5k binds Pin1 with a higher affinity compared to Pin4. The comparative analysis of molecular models of Pin1 and Pin4 with the selected compound, gave a rational explanation of the biochemical activity, and pinpointed the chemical elements that, if opportunely modified, may further improve inhibitory potency, pharmacological properties and selectivity of future peptide-based Parvulin inhibitors. Since 5k showed a limited cell penetration and no antiproliferative activity, it was conjugated to a polyarginine stretch, known to promote cell penetration of peptides, to obtain R8-5k derivative, which displayed an anti-proliferative effect on cancer cell lines compared to non-tumor cells. The effect of R8 on cell proliferation was also investigated. This work doubts the application of the R8 strategy for the development of cell penetrating antiproliferative peptides since it is not inert.

Juglone and KPT6566 Suppress the Tumorigenic Potential of CD44+CD133+ Tumor-Initiating Caco-2 Cells In Vitro and In Vivo

Pin1, a cis/trans isomerase of peptidyl-prolyl peptide bonds, plays a crucial role in the pathogenesis of many human cancers. Although chemical inhibitors of Pin1 show potent antitumor therapeutic properties against various cancers, their effect on colorectal cancer, especially colorectal tumor-initiating cells, remains unknown. Here, we investigated the effect of Juglone and KPT6566 on Caco-2 cells and tumor-initiating Caco-2 cells. Juglone and KPT6566 inhibited cell growth and colony formation, and induced apoptosis of Caco-2 cells. We also found that Juglone and KPT6566 downregulated expression of G1-phase-specific cyclins and cyclin-dependent kinases in a time-dependent manner, consistent with suppression of Caco-2 cell proliferation and colony formation. Although tumor-initiating cells are thought to be responsible for resistance to traditional chemotherapeutic drugs, our experiments demonstrate that Juglone or KPT6566 kill both tumor-initiating and non-tumor-initiating Caco-2 cells with equal or similar efficacy. Finally, when CD44⁺CD133⁺ tumor-initiating Caco-2 cells were injected into NSG mice, Juglone or KPT6566 led to a meaningful reduction in tumor volume and mass compared with tumors isolated from mice that received control treatment. Overall, these results indicate that chemical Pin1 inhibitors may be a valuable therapeutic option against colorectal tumor-initiating cancer cells.

Genome-wide association analysis for susceptibility to infection by Mycobacterium avium ssp. paratuberculosis in US Holsteins

Paratuberculosis, or Johne's disease, is a chronic, granulomatous, gastrointestinal tract disease of cattle and other ruminants caused by the bacterium Mycobacterium avium subspecies paratuberculosis (MAP). Control of Johne's disease is based on programs of testing and culling animals positive for infection with MAP and concurrently modifying management to reduce the likelihood of infection. The current study was motivated by the hypothesis that genetic variation in host susceptibility to MAP infection can be dissected and quantifiable associations with genetic markers identified. Two separate GWAS analyses were conducted, the first using 897 genotyped Holstein artificial insemination sires with phenotypes derived from incidence of MAP infection among daughters based on milk ELISA testing records. The second GWAS analysis was a case-control design using US Holstein cows phenotyped for MAP infection by serum ELISA or fecal culture tests. Cases included cows positive for either serum ELISA, fecal culture, or both. Controls consisted of animals negative for all tests conducted. A total of 376 samples (70 cases and 306 controls) from a University of Minnesota Johne's management demonstration project and 184 samples (76 cases and 108 controls) from a Michigan State University study were used. Medium-density (sires) and high-density (cows) genotype data were imputed to full genome sequence for the analyses. Marker-trait associations were analyzed using the single-step (ss)GWAS procedure implemented in the BLUPF90 suite of programs. Evidence of significant genomic contributions for susceptibility to MAP infection were observed on multiple chromosomes. Results were combined across studies in a meta-analysis, and increased support for genomic regions on BTA7 and BTA21 were observed. Gene set enrichment analysis suggested pathways for antigen processing and presentation, antimicrobial peptides and natural killer cell-mediated cytotoxicity are relevant to variation in host susceptibility to MAP infection, among others. Genomic prediction was evaluated using a 5-fold cross-validation, and moderate correlations were observed between genomic breeding value predictions and daughter averages (∼0.43 to 0.53) for MAP infection in testing data sets. These results suggest that genomic selection against susceptibility to MAP infection is feasible in Holstein cattle.

A Mini-Review on Structure-Activity Relationships of Glycyrrhetinic Acid Derivatives with Diverse Bioactivities

Pentacyclic triterpenoids, consisting of six isoprene units, are a kind of natural active substance. At present, numerous pentacyclic triterpene have been observed and classified into four subgroups of oleanane, ursane, lupane, and xylene on the basis of the carbon skeleton. Among them, oleanane is the most popular due to its rich backbone and diverse bioactivities. 18β-Glycyrrhetinic acid (GA), an oleanane-type pentacyclic triterpene isolated from licorice roots, possesses diverse bioactivities including antitumor, anti-inflammatory, antiviral, antimicrobial, enzyme inhibitor, hepatoprotective and so on. It has received more attention in medicinal chemistry due to the advantages of easy-to-access and rich bioactivity. Thus, numerous novel lead compounds were synthesized using GA as a scaffold. Herein, we summarize the structure-activity relationship and synthetic methodologies of GA derivatives from 2010 to 2020 as well as the most active GA derivatives. Finally, we anticipate that this review can benefit future research on structural modifications of GA to enhance bioactivity and provide an example for developing pentacyclic triterpene-based novel drugs.

Molecular Mechanisms of Parathyroid Disorders in Chronic Kidney Disease

Secondary hyperparathyroidism (SHP) is a common complication of chronic kidney disease (CKD) that induces morbidity and mortality in patients. How CKD stimulates the parathyroid to increase parathyroid hormone (PTH) secretion, gene expression and cell proliferation remains an open question. In experimental SHP, the increased PTH gene expression is post-transcriptional and mediated by PTH mRNA–protein interactions that promote PTH mRNA stability. These interactions are orchestrated by the isomerase Pin1. Pin1 participates in conformational change-based regulation of target proteins, including mRNA-binding proteins. In SHP, Pin1 isomerase activity is decreased, and thus, the Pin1 target and PTH mRNA destabilizing protein KSRP fails to bind PTH mRNA, increasing PTH mRNA stability and levels. An additional level of post-transcriptional regulation is mediated by microRNA (miRNA). Mice with parathyroid-specific knockout of Dicer, which facilitates the final step in miRNA maturation, lack parathyroid miRNAs but have normal PTH and calcium levels. Surprisingly, these mice fail to increase serum PTH in response to hypocalcemia or uremia, indicating a role for miRNAs in parathyroid stimulation. SHP often leads to parathyroid hyperplasia. Reduced expressions of parathyroid regulating receptors, activation of transforming growth factor α-epidermal growth factor receptor, cyclooxygenase 2-prostaglandin E2 and mTOR signaling all contribute to the enhanced parathyroid cell proliferation. Inhibition of mTOR by rapamycin prevents and corrects the increased parathyroid cell proliferation of SHP. This review summarizes the current knowledge on the mechanisms that stimulate the parathyroid cell at multiple levels in SHP.

The CSY-protecting group in the microwave-assisted synthesis of aggregation-prone peptides

This report describes the application of cyanosulfurylide (CSY)-protected aspartatic acid building blocks in microwave-assisted synthesis of aggregation-prone protein domains. We present a synthesis of Fmoc-Asp(CSY)-OH on a multigram scale, as...

Phosphopeptide enrichment using Phos-tag technology reveals functional phosphorylation of the nucleocapsid protein of SARS-CoV-2

Phosphorylation of viral proteins serves as a regulatory mechanism during the intracellular life cycle of infected viruses. There is therefore a pressing need to develop a method to efficiently purify and enrich phosphopeptides derived from viral particles in biological samples. In this study, we utilized Phos-tag technology to analyze the functional phosphorylation of the nucleocapsid protein (N protein; NP) of severe respiratory syndrome coronavirus 2 (SARS-CoV-2). Viral particles were collected from culture supernatants of SARS-CoV-2-infected VeroE6/TMPRSS2 cells by ultracentrifugation, and phosphopeptides were purified by Phos-tag magnetic beads for LC-MS/MS analysis. Analysis revealed that NP was reproducibly phosphorylated at serine 79 (Ser79). Multiple sequence alignment and phylogenetic analysis showed that the Ser79 was a distinct phospho-acceptor site in SARS-CoV-2 but not in other beta-coronaviruses. We also found that the prolyl-isomerase Pin1 bound to the phosphorylated Ser79 in NP and positively regulated the production of viral particles. These results suggest that SARS-CoV-2 may have acquired the potent virus-host interaction during its evolution mediated by viral protein phosphorylation. Moreover, Phos-tag technology can provide a useful means for analyzing the functional phosphorylation of viral proteins.

Significance

In this study, we aimed to investigate the functional phosphorylation of SARS-CoV-2 NP. For this purpose, we used Phos-tag technology to purify and enrich virus-derived phosphopeptides with high selectivity and reproducibility. This method can be particularly useful in analyzing viral phosphopeptides from cell culture supernatants that often contain high concentrations of fetal bovine serum and supplements. We newly identified an NP phosphorylation site at Ser79, which is important for Pin1 binding. Furthermore, we showed that the interaction between Pin1 and phosphorylated NP could enhance viral replication in a cell culture model.

Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 directly binds and stabilizes Nrf2 in breast cancer

Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) has been frequently overexpressed in many types of malignancy, suggesting its oncogenic function. It recognizes phosphorylated serine or threonine (pSer/Thr) of a target protein and isomerizes the adjacent proline (Pro) residue, thereby altering folding, subcellular localization, stability, and function of target proteins. The oncogenic transcription factor, Nrf2 harbors the pSer/Thr-Pro motif. This prompted us to investigate whether Pin1 could bind to Nrf2 and influence its stability and function in the context of implications for breast cancer development and progression. The correlation between Pin1 and Nrf2 in the triple-negative breast cancer cells was validated by RNASeq analysis as well as immunofluorescence staining. Interaction between Pin1 and Nrf2 was assessed by co-immunoprecipitation and an in situ proximity ligation assay. We found that mRNA and protein levels of Pin1 were highly increased in the tumor tissues of triple-negative breast cancer patients and the human breast cancer cell line. Genetic or pharmacologic inhibition of Pin1 enhanced the ubiquitination and degradation of Nrf2. In contrast, the overexpression of Pin1 resulted in the accumulation of Nrf2 in the nucleus, without affecting its transcription. Notably, the phosphorylation of Nrf2 at serine 215, 408, and 577 is essential for its interaction with Pin1. We also identified phosphorylated Ser104 and Thr277 residues in Keap1, a negative regulator of Nrf2, for Pin1 binding. Pin1 plays a role in breast cancer progression through stabilization and constitutive activation of Nrf2 by competing with Keap1 for Nrf2 binding.

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.

A novel nickel-modified nano-magnetite for isolation of histidine-tagged proteins expressed in Escherichia coli

Nano-magnetite with superparamagnetism could be coated by some organic compounds or by nano Au or Pt via surface modifications with multi-step reactions for the applications of isolating histidine-tagged (His-tagged) proteins. Introducing active sites of binding histidine onto the surface of nano-magnetite was the ultimate task. However, multi-step treatments might result in departure of the coatings from the surface of the nano-magnetite, which led to loss of active sites. In this work, we reported a convenient and efficient way of treating nano-magnetites and applied them in isolating His-tagged proteins. Carboxylates were introduced on the surface of home-made nano-magnetite directly via ultrasonic mixing with sodium bitartrate rather than complicated surface modifications, which was proved by thermogravimetric analyses. Ni²⁺ was, therefore, caught by the carboxylates of the coating via the coordinate interaction, demonstrated by X-ray photoelectron spectra. The coated magnetic nanoparticles with the bonded Ni²⁺ were successfully employed to selectively bind and separate recombinant His-tagged proteins directly from the mixture of Escherichia coli cell lysate, and showed wonderful affinity for His-tagged proteins with the saturated adsorption amount being 556 mg g^-1. Additionally, such functionalized nano-magnetite manifested the excellent recyclability in isolating His-tagged proteins.

Sulfopin is a covalent inhibitor of Pin1 that blocks Myc-driven tumors in vivo

The peptidyl-prolyl isomerase, Pin1, is exploited in cancer to activate oncogenes and inactivate tumor suppressors. However, despite considerable efforts, Pin1 has remained an elusive drug target. Here, we screened an electrophilic fragment library to identify covalent inhibitors targeting Pin1's active site Cys113, leading to the development of Sulfopin, a nanomolar Pin1 inhibitor. Sulfopin is highly selective, as validated by two independent chemoproteomics methods, achieves potent cellular and in vivo target engagement and phenocopies Pin1 genetic knockout. Pin1 inhibition had only a modest effect on cancer cell line viability. Nevertheless, Sulfopin induced downregulation of c-Myc target genes, reduced tumor progression and conferred survival benefit in murine and zebrafish models of MYCN-driven neuroblastoma, and in a murine model of pancreatic cancer. Our results demonstrate that Sulfopin is a chemical probe suitable for assessment of Pin1-dependent pharmacology in cells and in vivo, and that Pin1 warrants further investigation as a potential cancer drug target.

A molecular link between diabetes and breast cancer: Therapeutic potential of repurposing incretin-based therapies for breast cancer

Female breast cancer recently surpassed lung cancer and became the most commonly diagnosed cancer worldwide. As per the recent data from WHO, breast cancer accounts for one out of every 8 cancer cases diagnosed among an estimated 2.3 million new cancer cases. Breast cancer is the most prevailing cancer type among women causing the highest number of cancer-related mortality. It has been estimated that in 2020, 68,5000 women died due to this disease. Breast cancers have varying degrees of molecular heterogeneity; therefore, they are divided into various molecular clinical sub types. Recent reports suggest that type 2 diabetes (one of the common chronic diseases worldwide) is linked to the higher incidence, accelerated progression, and aggressiveness of different cancers; especially breast cancer. Breast cancer is hormone-dependent in nature and has a cross-talk with metabolism. A number of antidiabetic therapies are known to exert beneficial effects on various types of cancers, including breast cancer. However, only a few reports are available on the role of incretin-based antidiabetic therapies in cancer as a whole and in breast cancer in particular. The present review sheds light on the potential of incretin based therapies on breast cancer and explores the plausible underlying mechanisms. Additionally, we have also discussed the sub types of breast cancer as well as the intricate relationship between diabetes and breast cancer.

The Suppression of Pin1-Alleviated Oxidative Stress through the p38 MAPK Pathway in Ischemia- and Reperfusion-Induced Acute Kidney Injury

Background

Pin1, as the peptidyl-prolyl isomerase, plays a vital role in cellular processes. However, whether it has a regulatory effect on renal ischemia and reperfusion (I/R) injury still remains unknown.

Methods

The hypoxia/reoxygenation (H/R) model in human kidney (HK-2) cells and the I/R model in rats were assessed to investigate the role of Pin1 on I/R-induced acute kidney injury. Male Sprague-Dawley rats were used to establish the I/R model for 15, 30, and 45 min ischemia and then 24 h reperfusion, with or without the Pin1 inhibitor, to demonstrate the role of Pin1 in acute kidney injury. HK-2 cells were cultured and experienced the H/R model to identify the molecular mechanisms involved.

Results

In this study, we found that Pin1 and oxidative stress were obviously increased after renal I/R. Inhibition of Pin1 with juglone decreased renal structural and functional injuries, as well as oxidative stress. Besides, Pin1 inhibition with the inhibitor, juglone, or the small interfering RNA showed significant reduction on oxidative stress markers caused by the H/R process in vitro. Furthermore, the results indicated that the expression of p38 MAPK was increased during H/R in vitro and Pin1 inhibition could reduce the increased expression of p38 MAPK.

Conclusion

Our results illustrated that Pin1 aggravated renal I/R injury via elevating oxidative stress through activation of the p38 MAPK pathway. These findings indicated that Pin1 might become the potential treatment for renal I/R injury.

FBXW7 induces apoptosis in glioblastoma cells by regulating HDAC7

Glioblastoma is an aggressive type of brain cancer with an extremely poor prognosis. Additionally, the F-box WD repeat-containing protein 7 (FBXW7) is a component of the ubiquitin-proteasome system that has been widely implicated in human cancers. In this study, we investigated the role and mechanism of FBXW7 in glioblastoma. FBXW7 expression was analyzed in normal and glioblastoma tissue samples using The Cancer Genome Atlas Glioblastoma Multiforme (TCGA-GBM) database. Then, quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to examine mRNA expression, whereas, western blot analysis was conducted to determine protein levels of the samples. Furthermore, cell apoptosis was assessed using the Annexin V staining method, followed by flow cytometry analysis. Immunoprecipitation (IP) assay was conducted as well to test protein-protein interactions. Lastly, protein expression in tissues was examined by conducting immunohistochemistry (IHC). Results showed that the glioblastoma tissue samples displayed an FBXW7 downregulation compared with normal tissues. In vitro, the overexpression of FBXW7 in glioblastoma cells induced apoptosis, whereas, its knockdown displayed the opposite effect. Mechanistically, FBXW7 interacted with HDAC7 to promote HDAC7 ubiquitination, however, the overexpression of HDAC7 in glioblastoma cells blocked FBXW7-induced apoptosis. Finally, FBXW7 and HDAC7 displayed an inverse correlation in glioblastoma tissues in vivo. Therefore, our data demonstrated an important function of FBXW7 in promoting glioblastoma apoptosis by interacting with HDAC7 and promoting HDAC7 ubiquitination.

SlyD Accelerates trans-to-cis Prolyl Isomerization in a Mechanosignaling Protein under Load

Prolyl isomerization is recognized as one of the key regulatory mechanisms, which plays a crucial role in cell signaling, ion channel gating, phage virus infection, and molecular timing. This isomerization is usually slow but often accelerated by an enzyme, called peptidyl-prolyl isomerase (PPIase). In the current project, we investigate using single-molecule force spectroscopy (SMFS) the impact of a bacterial PPIase, SlyD, on the cis-trans isomerization of the proline 2225 (P2225) in an isolated 20th domain of a cytoskeletal mechanosensing protein filamin-A (FlnA20). To explore the FlnA20-PPIase interaction, we have used multiple SMFS modes, like constant velocity, constant distance, and jumping trap experiments. In our previous study, we reported the unique nature of the P2225, which is conserved in all naturally occurring filamins and can slowly (minutes) interconvert between cis-trans isomers, in absence of any PPIase. Our current results show a staggering 25-fold acceleration of the trans-to-cis isomerization rate in the presence of saturating SlyD concentration (7.25 μM) compared to the unenzymatic condition. A SlyD concentration-dependent depletion of the trans isomeric lifetime was also observed. Additionally, we observed that SlyD stabilizes the cis-isomer in the native state of FlnA20 by ∼2 k_BT. This is the first single-molecule observation of the cis-trans isomerization catalysis by a PPIase in a mechanosensing protein.

Cis P-tau underlies vascular contribution to cognitive impairment and dementia and can be effectively targeted by immunotherapy in mice

Compelling evidence supports vascular contributions to cognitive impairment and dementia (VCID) including Alzheimer's disease (AD), but the underlying pathogenic mechanisms and treatments are not fully understood. Cis P-tau is an early driver of neurodegeneration resulting from traumatic brain injury, but its role in VCID remains unclear. Here, we found robust cis P-tau despite no tau tangles in patients with VCID and in mice modeling key aspects of clinical VCID, likely because of the inhibition of its isomerase Pin1 by DAPK1. Elimination of cis P-tau in VCID mice using cis-targeted immunotherapy, brain-specific Pin1 overexpression, or DAPK1 knockout effectively rescues VCID-like neurodegeneration and cognitive impairment in executive function. Cis mAb also prevents and ameliorates progression of AD-like neurodegeneration and memory loss in mice. Furthermore, single-cell RNA sequencing revealed that young VCID mice display diverse cortical cell type-specific transcriptomic changes resembling old patients with AD, and the vast majority of these global changes were recovered by cis-targeted immunotherapy. Moreover, purified soluble cis P-tau was sufficient to induce progressive neurodegeneration and brain dysfunction by causing axonopathy and conserved transcriptomic signature found in VCID mice and patients with AD with early pathology. Thus, cis P-tau might play a major role in mediating VCID and AD, and antibody targeting it may be useful for early diagnosis, prevention, and treatment of cognitive impairment and dementia after neurovascular insults and in AD.

The Association Between Cancer and Spousal Rate of Memory Decline: A Negative Control Study to Evaluate (Unmeasured) Social Confounding of the Cancer-memory Relationship

Cancer diagnoses are associated with better long-term memory in older adults, possibly reflecting a range of social confounders that increase cancer risk but improve memory. We used spouse's memory as a negative control outcome to evaluate this possible confounding, since spouses share social characteristics and environments, and individuals' cancers are unlikely to cause better memory among their spouses. We estimated the association of an individual's incident cancer diagnosis (exposure) with their own (primary outcome) and their spouse's (negative control outcome) memory decline in 3601 couples from 1998 to 2014 in the Health and Retirement Study, using linear mixed-effects models. Incident cancer predicted better long-term memory for the diagnosed individual. We observed no association between an individual's cancer diagnosis and rate of spousal memory decline. This negative control study suggests that the inverse association between incident cancer and rate of memory decline is unlikely to be attributable to social/behavioral factors shared between spouses.

PIN1 Protects Hair Cells and Auditory HEI-OC1 Cells against Senescence by Inhibiting the PI3K/Akt/mTOR Pathway

A growing amount of evidence has confirmed the crucial role of the prolyl isomerase PIN1 in aging and age-related diseases. However, the mechanism of PIN1 in age-related hearing loss (ARHL) remains unclear. Pathologically, ARHL is primarily due to the loss and dysfunction of hair cells (HCs) and spiral ganglion cells (SGCs) in the cochlea. Therefore, in this study, we aimed to investigate the role of PIN1 in protecting hair cells and auditory HEI-OC1 cells from senescence. Enzyme-linked immunosorbent assays, immunohistochemistry, and immunofluorescence were used to detect the PIN1 protein level in the serum of ARHL patients and C57BL/6 mice in different groups, and in the SGCs and HCs of young and aged C57BL/6 mice. In addition, a model of HEI-OC1 cell senescence induced by H2O2 was used. Adult C57BL/6 mice were treated with juglone, or juglone and NAC, for 4 weeks. Interestingly, we found that the PIN1 protein expression decreased in the serum of patients with ARHL, in senescent HEI-OC1 cells, and in the cochlea of aged mice. Moreover, under H2O2 and juglone treatment, a large amount of ROS was produced, and phosphorylation of p53 was induced. Importantly, PIN1 expression was significantly increased by treatment with the p53 inhibitor pifithrin-α. Overexpression of PIN1 reversed the increased level of p-p53 and rescued HEI-OC1 cells from senescence. Furthermore, PIN1 mediated cellular senescence by the PI3K/Akt/mTOR signaling pathway. In vivo data from C57BL/6 mice showed that treatment with juglone led to hearing loss. Taken together, these findings demonstrated that PIN1 may act as a vital modulator in hair cell and HEI-OC1 cell senescence.

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 role of microRNAs in epithelial to mesenchymal transition and cancers; focusing on mir-200 family

Epithelial to mesenchymal transition (EMT) is a process associated with cancer malignancy and metastases. Cells undergoing EMT lose their epithelial phenotype and acquire mesenchymal phenotype. This process is accompanied by several molecular changes such as decrease of E-cadherin and increase of N-cadherin which is called the "cadherin swich". MicroRNAs (miRNAs, miRs) are small non-coding RNAs having ability to regulate genes post-transcriptionally. Nowadays they are believed to take part in multiple physiological and pathological processes including cancer development. Comparison between TargetScan7 (www.targetscan.org) results for miR-200b and metanalysis of genes involved in EMT showed that miR-200b has a potential binding site in 60 genes that are involved in EMT (the majority of them were associated with mesenchymal phenotype). Our review summarizes literature findings contributing to experimentally proven interactions between miR-200b and genes involved in EMT process including cell receptors, signaling pathways, cell cycle or cell adhesion. The results of those interactions indicate that miR-200b may have an inhibitory impact on EMT or even in selected cases is able to restore epithelial phenotype.

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.

(-)-Epigallocatechin-3-gallate induces apoptosis and differentiation in leukaemia by targeting reactive oxygen species and PIN1

(-)-Epigallocatechin-3-gallate (EGCG), the major active polyphenol extracted from green tea, has been shown to induce apoptosis and inhibit cell proliferation, cell invasion, angiogenesis and metastasis. Herein, we evaluated the in vivo effects of EGCG in acute myeloid leukaemia (AML) using an acute promyelocytic leukaemia (APL) experimental model (PML/RARα). Haematological analysis revealed that EGCG treatment reversed leucocytosis, anaemia and thrombocytopenia, and prolonged survival of PML/RARα mice. Notably, EGCG reduced leukaemia immature cells and promyelocytes in the bone marrow while increasing mature myeloid cells, possibly due to apoptosis increase and cell differentiation. The reduction of promyelocytes and neutrophils/monocytes increase detected in the peripheral blood, in addition to the increased percentage of bone marrow cells with aggregated promyelocytic leukaemia (PML) bodies staining and decreased expression of PML-RAR oncoprotein corroborates our results. In addition, EGCG increased expression of neutrophil differentiation markers such as CD11b, CD14, CD15 and CD66 in NB4 cells; and the combination of all-trans retinoic acid (ATRA) plus EGCG yield higher increase the expression of CD15 marker. These findings could be explained by a decrease of peptidyl-prolyl isomerase NIMA-interacting 1 (PIN1) expression and reactive oxygen species (ROS) increase. EGCG also decreased expression of substrate oncoproteins for PIN1 (including cyclin D1, NF-κB p65, c-MYC, and AKT) and 67 kDa laminin receptor (67LR) in the bone marrow cells. Moreover, EGCG showed inhibition of ROS production in NB4 cells in the presence of N-acetyl-L-cysteine (NAC), as well as a partial blockage of neutrophil differentiation and apoptosis, indicating that EGCG-activities involve/or are in response of oxidative stress. Furthermore, apoptosis of spleen cells was supported by increasing expression of BAD and BAX, parallel to BCL-2 and c-MYC decrease. The reduction of spleen weights of PML/RARα mice, as well as apoptosis induced by EGCG in NB4 cells in a dose-dependent manner confirms this assumption. Our results support further evaluation of EGCG in clinical trials for AML, since EGCG could represent a promising option for AML patient ineligible for current mainstay treatments.