Polo-like Kinase Research Articles

Riddelline from Tamarix articulate as a potential anti-bacterial lead compound for novel antibiotics discovery: A comprehensive computational and toxicological studies.

Tamarix articulate from the Tamaricaece family is a halophytic plant. This plant is commonly called Athal or Tamarix in different Arabic and Asian countries. Due to the high load of polyphenolic phytochemicals, the plant has been used as a therapeutic option against several diseases for decades. The plant is an anti-inflammatory, anti-bacterial, anti-viral, anti-cancer, anti-oxidant, and anti-inflammatory. In this work, the 222 phytochemical compounds of T. articulate from our previous study are used in different bioinformatic and biophysics techniques to explore their biological potency against different anti-bacterial, anti-cancer and anti-viral targets. By doing so, it was found that Riddelline ranked as the best binding molecule of biological macromolecules selected herein in particular the bacterial targets. The binding energy value of the compound for the KdsA enzyme was -14.64 kcal/mol, KdsB (-13.09 kcal/mol), MurC (-13.67 kcal/mol), MurD (-13.54 kcal/mol), MurF (-14.20 kcal/mol), Polo-like kinase 1 (Plk1) (-12.34 kcal/mol), Bcl-2 protein (-13.39 kcal/mol), SARS-CoV-2 main protease enzyme (-12.67 kcal/mol), and Human T cell leukemia virus protease (-13.67 kcal/mol). The mean Rg value of KdsA-Riddelline complex and KdsA-FPE complex is 32.67 Å, and average RMSD of KdsA-Riddelline complex and KdsA-FPE complex is 2.31 Å, respectively. The binding energy complexes was found to be dominated by van der Waals (-71.98 kcal/mol for KdsA-Riddelline complex and -65.09 kcal/mol for KdsA-FPE complex). The lead compound was also unveiled to show favorable druglike properties and pharmacokinetics. Together, the data suggest the good anti-bacterial activities of the T. articulate phytochemicals and thus can be subjected to experimental in vitro and in vivo investigations.

Sterile Alpha Motif Domain-Containing 5 Suppresses Malignant Phenotypes and Tumor Growth in Breast Cancer: Regulation of Polo-Like Kinase 1 and c-Myc Signaling in a Xenograft Model.

Background Breast cancer, particularly the triple-negative breast cancer (TNBC) subtype, remains a significant clinical challenge due to its resistance to standard chemotherapy and high recurrence rate. In this study, we explored the role of Sterile Alpha Motif Domain-Containing 5 (SAMD5) as a potential regulatory partner with the c-Myc oncogenic signaling pathway in breast cancer. Materials and methods Functional assays were conducted to investigate the effects of SAMD5 overexpression on cell viability, colony formation, and invasive behavior in TNBC cell lines. This study further assessed the expression levels of proliferation and invasion markers, including Ki67 (a marker for cell proliferation), Matrix Metalloproteinase-2 (MMP2), and Matrix Metalloproteinase-9 (MMP9). Mechanistic analyses identified a negative correlation between SAMD5 and Polo-like Kinase 1 (PLK1), a gene frequently overexpressed in breast cancer, particularly in TNBC. The effects of PLK1 knockdown on cell viability, colony formation, and invasion were observed, along with the impact of PLK1 overexpression on SAMD5's inhibitory activity. In vivo studies were performed using a xenograft tumor model in nude mice to evaluate the impact of SAMD5 overexpression on tumor weight and volume. Results SAMD5 overexpression significantly reduced cell viability, colony formation, and invasion in TNBC cells, and downregulated key proteins in the c-Myc signaling pathway, including c-Myc itself, β-catenin, Cyclin-Dependent Kinase 4 (CDK4), Cyclin-Dependent Kinase 6 (CDK6), and Cyclin D1. PLK1 overexpression was found to counteract SAMD5's inhibitory effects. In vivo experiments demonstrated that SAMD5 overexpression led to a marked reduction in tumor weight and volume, effects that were partially reversed by PLK1 overexpression. Conclusions SAMD5 acts as a tumor suppressor in breast cancer, particularly in TNBC, by inhibiting critical cellular processes and downregulating the c-Myc signaling pathway. This effect appears to be mediated, in part, through its negative association with PLK1. Targeting the SAMD5/PLK1 axis offers a promising therapeutic strategy for addressing aggressive breast cancers.

Polo-like kinase 2 targeting as novel strategy to sensitize mutant p53-expressing tumor cells to anticancer treatments.

Polo-like kinase 2 (Plk2) belongs to a family of serine/threonine kinases, and it is involved in tumorigenesis of diverse kind of tissues. We previously reported that Plk2 gene was a transcriptional target of the mutant p53/NF-Y oncogenic complex. Plk2 protein can bind to and phosphorylate mutant p53 triggering an oncogenic autoregulatory feedback loop involved in cancer cell proliferation and chemoresistance. In this study, we aimed to assess whether the specific inhibition of Plk2 kinase activity by the selective TC-S 7005 inhibitor could decrease cell proliferation and migration inhibiting mutant p53 phosphorylation, thus disarming its oncogenic potential. We found that the Plk2 inhibitor treatment sensitized the cells to the irradiation and chemotherapy drugs, thereby overcoming the mutant p53-dependent chemoresistance. Taken together, we provided results that Plk2 could be considered a tractable pharmacological target for cancers expressing mutant p53 proteins. The combined treatment with conventional chemotherapeutic drugs and Plk2 inhibitors may represent a new candidate intervention approach, which may be considered for improving tumor cell sensitivity to DNA damaging drugs. KEY MESSAGES : Missense mutations are present in the TP53 gene in about half of all human cancers and correlate with poor patient outcome. Mutant p53 proteins exert gain of function (GOF) activities in tumor cells such as increased proliferation, genomic instability and resistance to therapies. Polo-like kinase 2 (PLK2) binds and phosphorylates mutant p53 protein strengthening its GOF activities. Pharmacologically targeting PLK2 weakens mutant p53 proteins and sensitizes tumor cells to therapeutic treatments.

Onvansertib in Combination With Chemotherapy and Bevacizumab in Second-Line Treatment of KRAS-Mutant Metastatic Colorectal Cancer: A Single-Arm, Phase II Trial.

This phase II study evaluated the efficacy and tolerability of onvansertib, a polo-like kinase 1 (PLK1) inhibitor, in combination with fluorouracil, leucovorin, and irinotecan (FOLFIRI) + bevacizumab for the second-line treatment of KRAS-mutant metastatic colorectal cancer (mCRC). This multicenter, open-label, single-arm study enrolled patients with KRAS-mutated mCRC previously treated with oxaliplatin and fluorouracil with or without bevacizumab. Patients received onvansertib (15 mg/m2 once daily on days 1-5 and 15-19 of a 28-day cycle) and FOLFIRI + bevacizumab (days 1 and 15). The primary end point was the objective response rate (ORR), and secondary endpoints included progression-free survival (PFS), duration of response (DOR), and tolerability. Translational and preclinical studies were conducted in KRAS-mutant CRC. Among the 53 patients treated, the confirmed ORR was 26.4% (95% CI, 15.3 to 40.3). The median DOR was 11.7 months (95% CI, 9.4 to not reached). Grade 3/4 adverse events were reported in 62% of patients. A post hoc analysis revealed that patients with no prior bevacizumab treatment had a significantly higher ORR and longer PFS compared with patients with prior bevacizumab treatment: ORR of 76.9% versus 10.0% (odds ratio of 30.0, P < .001) and median PFS of 14.9 months versus 6.6 months (hazard ratio of 0.16, P < .001). Our translational findings support that prior bevacizumab exposure contributes to onvansertib resistance. Preclinically, we showed that onvansertib inhibited the hypoxia pathway and exhibited robust antitumor activity in combination with bevacizumab through the inhibition of angiogenesis. Onvansertib in combination with FOLFIRI + bevacizumab showed significant activity in the second-line treatment of patients with KRAS-mutant mCRC, particularly in patients with no prior bevacizumab treatment. These findings led to the evaluation of the combination in the first-line setting (ClinicalTrails.gov identifier: NCT06106308).

Biomimetic Modification of siRNA/Chemo Drug Nanoassemblies for Targeted Combination Therapy in Breast Cancer.

The development and progression of tumors are characterized by intricate biological processes. Monotherapy not only struggles to achieve effective treatment but also tends to precipitate a series of issues, including multidrug resistance and limited antitumor effect. Consequently, it is imperative to adopt a synergistic multitherapy approach to enhance the efficacy of tumor treatment. The integration of chemotherapy drug with oligonucleotide drug for combinational treatment has shown significant promise in improving tumor therapeutic efficiency. However, the effective in vivo codelivery of oligonucleotide drugs and chemotherapy drugs faces substantial challenges such as poor stability of oligonucleotide drugs during the circulation time, limited tumor accumulation, and uncertain delivery ratios of different payloads. To overcome these obstacles, we have engineered cyclic Arg-Gly-Asp (cRGD)-modified red blood cell membrane (RBCm)-coated multidrug nanocomplexes, which were self-assembled from the Polo-like kinase 1 siRNA (siPlk1) and an irreversible tyrosine kinase inhibitor neratinib targeted to human epidermal growth factor receptor 2 (HER2) overexpressed in breast cancer. Through electrostatic and amphiphilic interactions between the positively charged neratinib and negatively charged siPlk1, we have successfully fabricated uniform multidrug nanoparticles. The cRGD-modified red blood cell membranes coated on the surface of the multidrug nanoparticles could enhance drug stability in circulation and tumor accumulation. This targeted combinational therapy significantly enhanced the antitumor efficiency in HER2-positive breast cancer in vitro and in vivo.

Centrioles are frequently amplified in early B cell development but dispensable for humoral immunity

Centrioles define centrosome structure and function. Deregulation of centriole numbers can cause developmental defects and cancer. The p53 tumor suppressor limits the growth of cells lacking or harboring additional centrosomes and can be engaged by the “mitotic surveillance” or the “PIDDosome pathway”, respectively. Here, we show that early B cell progenitors frequently present extra centrioles, ensuing their high proliferative activity and related DNA damage. Extra centrioles are efficiently cleared during B cell maturation. In contrast, centriole loss upon Polo-like kinase 4 (Plk4) deletion causes apoptosis and arrests B cell development. This defect can be rescued by co-deletion of Usp28, a critical component of the mitotic surveillance pathway, that restores cell survival and maturation. Centriole-deficient mature B cells are proliferation competent and mount a humoral immune response. Our findings imply that progenitor B cells are intolerant to centriole loss but permissive to centriole amplification, a feature potentially facilitating their malignant transformation.

Polo-like Kinase 1 Predicts Lymph Node Metastasis in Middle Eastern Colorectal Cancer Patients; Its Inhibition Reverses 5-Fu Resistance in Colorectal Cancer Cells.

Polo-like kinase 1 (PLK1) is a serine/threonine-protein kinase essential for regulating multiple stages of cell cycle progression in mammals. Aberrant regulation of PLK1 has been observed in numerous human cancers and is linked to poor prognoses. However, its role in the pathogenesis of colorectal cancer (CRC) in the Middle East remains unexplored. PLK1 overexpression was noted in 60.3% (693/1149) of CRC cases and was significantly associated with aggressive clinico-pathological parameters and p-ERK1/2 overexpression. Intriguingly, multivariate logistic regression analysis identified PLK1 as an independent predictor of lymph node metastasis. Our in vitro experiments demonstrated that CRC cells with high PLK1 levels were resistant to 5-Fu treatment, while those with low PLK1 expression were sensitive. To investigate PLK1's role in chemoresistance, we used the specific inhibitor volasertib, which effectively reversed 5-Fu resistance. Interestingly, forced PLK1 expression activated the CRAF-MEK-ERK signaling cascade, while its inhibition suppressed this cascade. PLK1 knockdown reduced epithelial-to-mesenchymal transition (EMT) progression and stem cell-like traits in 5-Fu-resistant cells, implicating PLK1 in EMT induction and stemness in CRC. Moreover, silencing ERK1/2 significantly mitigated chemoresistance, EMT, and stemness properties in CRC cell lines that express PLK1. Furthermore, the knockdown of Zeb1 attenuated EMT and stemness, suggesting a possible link between EMT activation and the maintenance of stemness in CRC. Our findings underscore the pivotal role of PLK1 in mediating chemoresistance and suggest that PLK1 inhibition may represent a potential therapeutic strategy for the management of aggressive colorectal cancer subtypes.

Multigram-scale synthesis of volasertib, an inhibitor of polo-like kinases in clinical evaluation

Multigram-scale synthesis of volasertib, an inhibitor of polo-like kinases in clinical evaluation

Pachytene piRNAs control discrete meiotic events during spermatogenesis and restrict gene expression in space and time.

Pachytene piRNAs, a Piwi-interacting RNA subclass in mammals, are hypothesized to regulate non-transposon sequences during spermatogenesis. Caenorhabditis elegans piRNAs, the 21URNAs, are implicated in regulating coding sequences; the messenger RNA targets and biological processes they control during spermatogenesis are largely unknown. We demonstrate that loss of 21URNAs compromises homolog pairing and makes it permissive for nonhomologous synapsis resulting in defects in crossover formation and chromosome segregation during spermatogenesis. We identify Polo-like kinase 3 (PLK-3), among others, as a 21URNA target. 21URNA activity restricts PLK-3 protein to proliferative cells, and expansion of PLK-3 in pachytene overlaps with the meiotic defects. Removal of plk-3 results in quantitative genetic suppression of the meiotic defects. One discrete 21URNA inhibits PLK-3 expression in late pachytene cells. Together, these results suggest that the 21URNAs function as pachytene piRNAs during C. elegans spermatogenesis. We identify their targets and meiotic events and highlight the remarkable intricacy of this multi-effector mechanism during spermatogenesis.

CENP-C-targeted PLK-1 regulates kinetochore function in C. elegans embryos.

Polo-like kinase 1 (PLK-1) is present in centrosomes, the nuclear envelope, and kinetochores and plays a significant role in meiosis and mitosis. PLK-1 depletion or inhibition has severe consequences for spindle assembly, spindle assembly checkpoint (SAC) activation, chromosome segregation, and cytokinesis. BUB-1 targets PLK-1 to the outer kinetochore and, in mammals, the inner kinetochore PLK1 targeting is mediated by the constitutive centromere associated network (CCAN). BUB1-targeted PLK-1 plays a key role in SAC activation and a SAC-independent role through targeting CDC-20. In contrast, whether there is a specific, non-redundant role for inner kinetochore targeted PLK-1 is unknown. Here, we used the C. elegans embryo to study the role of inner kinetochore PLK-1. We found that CENP-C, the sole CCAN component in C. elegans and other species, targets PLK-1 to the inner kinetochore during prometaphase and metaphase. Disruption of the CENP-C/PLK-1 interaction leads to an imbalance in kinetochore components and a defect in chromosome congression, without affecting CDC-20 recruitment. These findings indicate that PLK-1 kinetochore recruitment by CENP-C has at least partially distinct functions than outer kinetochore PLK-1, providing a platform for a better understanding of the different roles played by PLK-1 during mitosis.

Rational Design of HER2-Targeted Combination Therapies to Reverse Drug Resistance in Fibroblast-Protected HER2+ Breast Cancer Cells.

Fibroblasts, an abundant cell type in the breast tumor microenvironment, interact with cancer cells and orchestrate tumor progression and drug resistance. However, the mechanisms by which fibroblast-derived factors impact drug sensitivity remain poorly understood. Here, we develop rational combination therapies that are informed by proteomic profiling to overcome fibroblast-mediated therapeutic resistance in HER2+ breast cancer cells. Drug sensitivity to the HER2 kinase inhibitor lapatinib was characterized under conditions of monoculture and exposure to breast fibroblast-conditioned medium. Protein expression was measured using reverse phase protein arrays. Candidate targets for combination therapy were identified using differential expression and multivariate regression modeling. Follow-up experiments were performed to evaluate the effects of HER2 kinase combination therapies in fibroblast-protected cancer cell lines and fibroblasts. Compared to monoculture, fibroblast-conditioned medium increased the expression of plasminogen activator inhibitor-1 (PAI1) and cell cycle regulator polo like kinase 1 (PLK1) in lapatinib-treated breast cancer cells. Combination therapy of lapatinib with inhibitors targeting either PAI1 or PLK1, eliminated fibroblast-protected cancer cells, under both conditions of direct coculture with fibroblasts and protection by fibroblast-conditioned medium. Analysis of publicly available, clinical transcriptomic datasets revealed that HER2-targeted therapy fails to suppress PLK1 expression in stroma-rich HER2+ breast tumors and that high PAI1 gene expression associates with high stroma density. Furthermore, we showed that an epigenetics-directed approach using a bromodomain and extraterminal inhibitor to globally target fibroblast-induced proteomic adaptions in cancer cells, also restored lapatinib sensitivity. Our data-driven framework of proteomic profiling in breast cancer cells identified the proteolytic degradation regulator PAI1 and the cell cycle regulator PLK1 as predictors of fibroblast-mediated treatment resistance. Combination therapies targeting HER2 kinase and these fibroblast-induced signaling adaptations eliminates fibroblast-protected HER2+ breast cancer cells. The online version contains supplementary material available at 10.1007/s12195-024-00823-0.

USP18 promotes the proliferation, invasion, and migration of head and neck squamous cell carcinoma by deubiquitinating PLK1

The ubiquitin specific peptidase 18 (USP18), a well-established deubiquitinase, has been extensively implicated in the malignant progression of various human tumors. However, its role in head and neck squamous cell carcinoma (HNSC) requires further investigation. Here, we revealed that USP18 was significantly upregulated in HNSC and knockdown of USP18 markedly suppressed tumor growth in vivo. Furthermore, silencing USP18 attenuated HNSC cell proliferation, invasion, and migration, while overexpression of USP18 exerted converse effects. Mechanistically, USP18 diminished K48-linked ubiquitination of polo-like kinase 1 (PLK1) to stabilize the protein through its deubiquitinase activity. Subsequently, we validated that USP18 modulated PLK1 to activate the mTORC1 pathway, thereby facilitating HNSC cell proliferation, invasion, and migration. In conclusion, our findings demonstrate that elevated expression of USP18 in HNSC cells promotes tumorigenesis by regulating the PLK1-mTORC1 pathway.

NOD2 reduces the chemoresistance of melanoma by inhibiting the TYMS/PLK1 signaling axis

AbstractNucleotide-binding oligomerization domain 2 (NOD2) is an immune sensor crucial for eliciting the innate immune responses. Nevertheless, discrepancies exist regarding the effect of NOD2 on different types of cancer. This study aimed to investigate these function of NOD2 in melanoma and its underlying mechanisms. We have validated the tumor suppressor effect of NOD2 in melanoma. NOD2 inhibited the proliferation of melanoma cells, hindering their migration and invasion while promoting the onset of apoptosis. Our study showed that NOD2 expression is closely related to pyrimidine and folate metabolism. NOD2 inhibits thymidylate synthase (TYMS) expression by promoting K48-type ubiquitination modification of TYMS, thereby decreasing the resistance of melanoma cells to 5-fluorouracil (5-FU) and capecitabine (CAP). TYMS was identified to form a complex with Polo-like Kinase 1 (PLK1) and activate the PLK1 signaling pathway. Furthermore, we revealed that the combination of the PLK1 inhibitor volasertib (BI6727) with 5-FU or CAP had a synergistic effect repressing the proliferation, migration, and autophagy of melanoma cells. Overall, our research highlights the protective role of NOD2 in melanoma and suggests that targeting NOD2 and the TYMS/PLK1 signaling axis is a high-profile therapy that could be a prospect for melanoma treatment.

Pharmacological inhibition of PLK2 kinase activity mitigates cognitive decline but aggravates APP pathology in a sex-dependent manner in APP/PS1 mouse model of Alzheimer's disease

Converging evidence from clinical and experimental studies suggest the potential significance of Polo-like kinase 2 (PLK2) in regulating the phosphorylation and toxicity of the Alzheimer's disease (AD)-related protein, amyloid precursor protein (APP). These findings have prompted various experimental trials aimed at inhibiting PLK2 kinase activity in different transgenic mouse models of AD. While positive impacts on cognitive decline were reported in these studies, the cellular effects remained controversial. In the present study, we sought to assess the cognitive and cellular consequences of chronic PLK2 inhibitor treatment in the APP/PS1 transgenic mouse model of AD. First, we confirmed that inhibiting PLK2 prevented cognitive decline in a sex-dependent manner, particularly by enhancing working memory in male APP/PS1 mice. Surprisingly, cellular analysis revealed that treatment with PLK2 inhibitor increased the load of amyloid plaques and elevated levels of soluble amyloid β (Aβ) 40 and Aβ42 in the cortex, as well as insoluble Aβ42 in the hippocampus of female mice, without affecting APP pathology in males. These results underscore the potential of PLK2 inhibition to mitigate cognitive symptoms in males. However, paradoxically, it intensifies amyloid pathology in females by enhancing APP amyloidogenic processing, creating a controversial aspect to its therapeutic impact. Overall, these data highlight the sex-dependent nature of the effects of PLK2 inhibition, which may also be influenced by the genetic background of the transgenic mouse model utilized.

The role of polo-like kinases 2 in the proteasomal and lysosomal degradation of alpha-synuclein in neurons.

Parkinson's disease (PD) is a neurodegenerative disorder caused by the degeneration of dopaminergic neurons in the brain stem. PD is mostly sporadic, but familial PD (FPD) cases are recorded in different studies. The first gene mutation that is linked to FPD is α-synuclein (α-syn). It was then found that α-syn is also accumulated in Lewy body (LB), a classical pathological hallmark in PD patients. Different studies have shown that α-syn accumulation and aggregation can be a crucial factor contributing to the degeneration of dopaminergic neurons in PD. α-syn has been found to be degraded by the ubiquitin proteasomal system (UPS) and autophagy-lysosomal pathway (ALP). In this study, we initially explored how α-syn phosphorylation by GRK6, PLK2 and CK2α would facilitate its degradation in relation to the UPS or ALP. Unexpectedly, we found that the degradation of α-syn through PLK2 phosphorylation could be modulated by UPS and ALP in a novel mechanism. Specially, attenuation of UPS could increase the amount of PLK2 and then could facilitate the phosphorylation and degradation of α-syn through ALP. To test this further invivo, we attenuate the proteasomal activity in a well-established A53T α-syn transgenic PD mouse model. We found that attenuation of proteasomal activity in the A53T α-syn transgenic mice could reduce the accumulation of α-syn in the striatum and midbrain. Based on our results, this study provides a new insight into how α-syn is degraded through the UPS and ALP.

Progress in research of polo-like kinase 1 in hepatocellular carcinoma

Progress in research of polo-like kinase 1 in hepatocellular carcinoma

Novel insights into the circadian modulation of lipid metabolism in chicken livers revealed by RNA sequencing and weighted gene co-expression network analysis

The circadian clock is crucial for maintaining lipid metabolism homeostasis in mammals. Despite the economic importance of fat content in poultry, research on the regulatory effects and molecular mechanisms of the circadian clock on avian hepatic lipid metabolism has been limited. In this study, we observed significant diurnal variations (P<0.05) in triglyceride (TG), free fatty acids (FFA), fatty acid synthase (FAS), and total cholesterol (TC) levels in the chicken embryonic liver under 12-h light/12-h dark incubation conditions, with TG, FFA, and TC concentrations showing significant cosine rhythmic oscillations (P<0.05). However, such rhythmic variations were not observed under complete darkness incubation conditions. Using transcriptome sequencing technology, we identified 157 genes significantly upregulated at night and 313 genes significantly upregulated during the 12-h light/12-h dark cycle. These circadian differential genes are involved in processes and pathways such as lipid catabolic process regulation, meiotic cell cycle, circadian rhythm regulation, positive regulation of the MAPK cascade, and glycerolipid metabolism. Weighted gene co-expression network analysis (WGCNA) revealed 3 modules-green, blue, and red-that significantly correlate with FFA, FAS, and TG, respectively. Genes within these modules were enriched in processes and pathways including the cell cycle, light stimulus response, circadian rhythm regulation, phosphorylation, positive regulation of the MAPK cascade, and lipid biosynthesis. Notably, we identified ten hub genes, including protein kinase C delta (PRKCD), polo like kinase 4 (PLK4), clock circadian regulator (CLOCK), steroid 5 alpha-reductase 3 (SRD5A3), BUB1 mitotic checkpoint serine/threonine kinase (BUB1B), shugoshin 1 (SGO1), NDC80 kinetochore complex component (NDC80), NIMA related kinase 2 (NEK2), minichromosome maintenance complex component 4 (MCM4), polo like kinase 1 (PLK1), potentially link circadian regulation with lipid metabolic homeostasis. These findings demonstrate the regulatory role of the circadian clock in chicken liver lipid metabolism homeostasis and provide a theoretical basis and molecular targets for optimizing the circadian clock to reduce excessive fat deposition in chickens, which is significant for the healthy development of the poultry industry.

403 Impact of lysine, methionine, and histidine deficiencies on gene expression and upstream transcriptional regulators in bovine mammary epithelial cells: An RNA-sequencing analysis

Abstract Essential (E) amino acids (AA) may alter bovine mammary epithelial cell functions by impacting mRNA expression of genes through their upstream transcription factors. The objective of this research was to study the impact of EAA deficiencies on gene expression and to identify upstream transcriptional factors mediating their effects in bovine mammary epithelial cells. Epithelial cells were collected from the mammary glands of lactating dairy cows and cultured in combined media of DMEM/F12 and Medium 170, differentiated for 5 d, and subsequently treated in triplicate for 60 h with a control medium containing all EAA at normal plasma concentrations for cows (CTL), or a medium with 20 μM Lys (LY), 5 μM Met (LM), or 10 μM His (LH), which are each 25% of normal concentration. RNA was isolated from the cells and sequenced on an Illumina NovaSeq 6000 producing 150 base pair paired-end reads with a minimum sequencing depth of 150 million reads. Reads were cleaned with ‘fastp’ (Chen et al., 2018), aligned to the bovine reference genome (ARS-UCD1.2) using ‘STAR’ aligner (Dobin et al., 2013), and genes counted using ‘featureCounts’ (Liao et al., 2014). Differential expression of genes between treatment pairs was determined using the ‘DESeq2’ package (Love et al., 2014) in R. Genes with an absolute log2 fold change ≥ 1 and a false discovery rate of &amp;lt; 0.05 were considered differentially expressed. The number of differentially expressed genes relative to CTL was 780 for LY, 383 for LH, and 536 for LM. QIAGEN Ingenuity Pathway Analysis (IPA) identified four pathways consistently affected across LY, LM, and LH: kinetochore metaphase signaling, mitotic roles of polo-like kinase, cell cycle: G2/M DNA damage checkpoint regulation, and interferon signaling (Figure 1-3). Notably, the kinetochore metaphase signaling pathway was identified as the most significant across all treatments, suggesting a strong link to cell proliferation and apoptosis during EAA deficiency. The interferon signaling might be related to the Janus kinase 2/signal transducer and activator of transcription 5 (Jak2/STAT5) pathway which can promote the expression of genes encoding milk proteins such as β-casein and β-lactoglobulin. Furthermore, the IPA identified upstream transcription factors related to cell proliferation, apoptosis, autophagy, protein translation, endoplasmic reticulum biogenesis, and amino acid metabolism including NUPR1, FOXM1, MYC, CCND1, TP53, DDIT3, and ATF4 across all treatments. The findings suggest that AA deprivation regulates bovine mammary epithelial cell function by instigating amino acid response pathways and altering secretory cell number.

RXR nuclear receptor signaling modulates lipid metabolism and triggers lysosomal clearance of alpha-synuclein in neuronal models of synucleinopathy

Disease-modifying strategies for Parkinson disease (PD), the most common synucleinopathy, represent a critical unmet medical need. Accumulation of the neuronal protein alpha-synuclein (αS) and abnormal lipid metabolism have each been implicated in PD pathogenesis. Here, we elucidate how retinoid-X-receptor (RXR) nuclear receptor signaling impacts these two aspects of PD pathogenesis. We find that activated RXR differentially regulates fatty acid desaturases, significantly reducing the transcript levels of the largely brain-specific desaturase SCD5 in human cultured neural cells and PD patient-derived neurons. This was associated with reduced perilipin-2 protein levels in patient neurons, reversal of αS-induced increases in lipid droplet (LD) size, and a reduction of triglyceride levels in human cultured cells. With regard to αS proteostasis, our study reveals that RXR agonism stimulates lysosomal clearance of αS. Our data support the involvement of Polo-like kinase 2 activity and αS S129 phosphorylation in mediating this benefit. The lowering of cellular αS levels was associated with reduced cytotoxicity. Compared to RXR activation, the RXR antagonist HX531 had the opposite effects on LD size, SCD, αS turnover, and cytotoxicity, all supporting pathway specificity. Together, our findings show that RXR-activating ligands can modulate fatty acid metabolism and αS turnover to confer benefit in cellular models of PD, including patient neurons. We offer a new paradigm to investigate nuclear receptor ligands as a promising strategy for PD and related synucleinopathies.

Structure-guided Development of Novel Benzothiophene Derivatives as PLK1-PBD Inhibitors

Background: Polo-like kinase 1 (PLK1), a validated target for tumor therapy, plays a key role in mitosis and is over-expressed in many tumors. In addition to its N-terminal kinase domain, PLk1 also harbors a C-terminal polo-box domain (PBD). Objective: A candidate based on PLK1-PBD was developed as a promising compound for future development. Methods: Seventeen small molecule PLK1-PBD inhibitors were designed, synthesized and evaluated for PLK1-PBD inhibitory activities by fluorescence polarization (FP) assay. The compounds with better inhibitory activities were further assessed for their anti-proliferative activities using a CCK-8 method. Results: The inhibitory rates of compounds 7a, 7d, 14a, 14d, 14e and 14f exceeded 98%. The IC50 values of compounds 7d, 14d, 14e, and 14f were 0.73 μM, 0.67 μM, 0.89 μM and 0.26 μM, proving better than MCC1019. Compound 14f showed the best inhibitory activity (IC50: 0.26 μM) and antiproliferative activities against three cancer cell lines (HeLa, HepG2 and MG63). Especially, compound 14f also exhibited acceptable safety profiles in the human ether-a-go-go related gene (hERG) and normal cell tests. The results of docking and prediction studies indicated that compound 14f had a high binding affinity to the target, with good drug-like absorption, distribution, metabolism, elimination, and toxicity (ADMET) properties. Conclusion: Compound 14f can be a promising compound for future development.