RESUMEN

Prostate cancer progression is driven by androgen receptor (AR) activity, which is a target for therapeutic approaches. Enzalutamide is an AR inhibitor that prolongs the survival of patients with advanced prostate cancer. However, resistance mechanisms arise and impair its efficacy. One of these mechanisms is the expression of AR-V7, a constitutively active AR splice variant. The Mediator complex is a multisubunit protein that modulates gene expression on a genome-wide scale. MED12 and cyclin-dependent kinase (CDK)8, or its paralog CDK19, are components of the kinase module that regulates the proliferation of prostate cancer cells. In this study, we investigated how MED12 and CDK8/19 influence cancer-driven processes in prostate cancer cell lines, focusing on AR activity and the enzalutamide response. We inhibited MED12 expression and CDK8/19 activity in LNCaP (AR+, enzalutamide-sensitive), 22Rv1 (AR-V7+, enzalutamide-resistant), and PC3 (AR-, enzalutamide-insensitive) cells. Both MED12 and CDK8/19 inhibition reduced cell proliferation in all cell lines, and MED12 inhibition reduced proliferation in the respective 3D spheroids. MED12 knockdown significantly inhibited c-Myc protein expression and signaling pathways. In 22Rv1 cells, it consistently inhibited the AR response, prostate-specific antigen (PSA) secretion, AR target genes, and AR-V7 expression. Combined with enzalutamide, MED12 inhibition additively decreased the AR activity in both LNCaP and 22Rv1 cells. CDK8/19 inhibition significantly decreased PSA secretion in LNCaP and 22Rv1 cells and, when combined with enzalutamide, additively reduced proliferation in 22Rv1 cells. Our study revealed that MED12 and CDK8/19 regulate AR activity and that their inhibition may modulate response to enzalutamide in prostate cancer.

Asunto(s)

Benzamidas , Proliferación Celular , Quinasa 8 Dependiente de Ciclina , Quinasas Ciclina-Dependientes , Complejo Mediador , Nitrilos , Feniltiohidantoína , Neoplasias de la Próstata , Receptores Androgénicos , Feniltiohidantoína/farmacología , Masculino , Humanos , Receptores Androgénicos/metabolismo , Receptores Androgénicos/genética , Complejo Mediador/metabolismo , Complejo Mediador/genética , Línea Celular Tumoral , Neoplasias de la Próstata/tratamiento farmacológico , Neoplasias de la Próstata/metabolismo , Neoplasias de la Próstata/patología , Neoplasias de la Próstata/genética , Quinasas Ciclina-Dependientes/metabolismo , Quinasas Ciclina-Dependientes/genética , Quinasas Ciclina-Dependientes/antagonistas & inhibidores , Quinasa 8 Dependiente de Ciclina/metabolismo , Quinasa 8 Dependiente de Ciclina/genética , Proliferación Celular/efectos de los fármacos , Resistencia a Antineoplásicos/efectos de los fármacos , Resistencia a Antineoplásicos/genética , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos

RESUMEN

Complementary studies by Zhao et al.1 and Chen et al.2 reveal how an intrinsically disordered region in MED13 controls mutually exclusive binding of RNA Polymerase II and CDK8 kinase module to Mediator, switching Mediator and transcription activation on and off.

Asunto(s)

Quinasa 8 Dependiente de Ciclina , Complejo Mediador , ARN Polimerasa II , Complejo Mediador/metabolismo , Complejo Mediador/genética , Complejo Mediador/química , Quinasa 8 Dependiente de Ciclina/metabolismo , Quinasa 8 Dependiente de Ciclina/genética , ARN Polimerasa II/metabolismo , ARN Polimerasa II/genética , Humanos , Proteínas Intrínsecamente Desordenadas/metabolismo , Proteínas Intrínsecamente Desordenadas/química , Proteínas Intrínsecamente Desordenadas/genética , Unión Proteica , Activación Transcripcional

RESUMEN

Cyclin-dependent kinase 8 (CDK8) is highly expressed in various cancers and common complex human diseases, and an important therapeutic target for drug discovery and development. The CDK8 inhibitors are actively sought after, especially among natural products. We performed a virtual screening using the ZINC library comprising approximately 90,000 natural compounds. We applied Lipinski's rule of five, absorption, distribution, metabolism, excretion, and toxicity properties, and pan-assay interference compounds filter to eliminate promiscuous binders. Subsequently, the filtered compounds underwent molecular docking to predict their binding affinity and interactions with the CDK8 protein. Interaction analysis were carried out to elucidate the interaction mechanism of the screened hits with binding pockets of the CDK8. The ZINC02152165, ZINC04236005, and ZINC02134595 were selected with appreciable specificity and affinity with CDK8. An all-atom molecular dynamic (MD) simulation followed by essential dynamics was performed for 200 ns. Taken together, the results suggest that ZINC02152165, ZINC04236005, and ZINC02134595 can be harnessed as potential leads in therapeutic development. Moreover, the binding of the molecules brings change in protein conformation in a way that blocks the ATP-binding site of the protein, obstructing its kinase activity. These new findings from natural products offer insights into the molecular mechanisms underlying CDK8 inhibition. CDK8 was previously associated with behavioral and neurological diseases such as autism spectrum disorder, and cancers, for example, colorectal, prostate, breast, and acute myeloid leukemia. Hence, we call for further research and experimental validation, and with an eye to inform future clinical drug discovery and development in these therapeutic fields.

Asunto(s)

Antineoplásicos , Productos Biológicos , Quinasa 8 Dependiente de Ciclina , Inhibidores de Proteínas Quinasas , Humanos , Antineoplásicos/farmacología , Antineoplásicos/química , Sitios de Unión , Productos Biológicos/farmacología , Productos Biológicos/química , Quinasa 8 Dependiente de Ciclina/antagonistas & inhibidores , Quinasa 8 Dependiente de Ciclina/metabolismo , Quinasa 8 Dependiente de Ciclina/química , Descubrimiento de Drogas/métodos , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Unión Proteica , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/química

RESUMEN

Macrophages polarize into alternatively activated M2 macrophages through interleukin (IL)-4, and they express high levels of arginase-1, which promotes anti-inflammatory responses. Several studies have confirmed the anti-inflammatory effects of cyclin-dependent kinase (CDK) 8/19 inhibition, and hence, numerous CDK8/19 inhibitors, such as BRD6989, have been developed. However, the effects of CDK8/19 inhibitors on arginase-1 expression in macrophages have not yet been elucidated. This study investigated the effects of CDK8/19 inhibitor on arginase-1 expression in IL-4-activated macrophages. The results showed that BRD6989 increased arginase-1 expression transcriptionally in murine peritoneal macrophages and the murine macrophage cell line RAW264.7 in an IL-4-dependent manner. In addition, the results indicated that BRD6989 enhances signal transducer and activator of transcription (STAT) 6 phosphorylation. Meanwhile, BRD6989 exhibited the capability to activate p38 mitogen-activated protein kinase (MAPK） even in the absence of IL-4 stimulation. Moreover, we observed that a p38 MAPK inhibitor suppressed the BRD6989-induced increase in arginase-1 expression. Besides, BRD6989 increased the surface expression of CD206, an M2 macrophage marker. Thus, this study demonstrated for the first time that CDK8/19 inhibition increases arginase-1 expression, suggesting that this mechanism involves the activation of STAT6 and p38 MAPK. This finding implies that CDK8/19 inhibition may facilitate the production of anti-inflammatory M2 macrophages.

Asunto(s)

Arginasa , Quinasa 8 Dependiente de Ciclina , Quinasas Ciclina-Dependientes , Interleucina-4 , Factor de Transcripción STAT6 , Proteínas Quinasas p38 Activadas por Mitógenos , Animales , Arginasa/metabolismo , Arginasa/antagonistas & inhibidores , Factor de Transcripción STAT6/metabolismo , Ratones , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Células RAW 264.7 , Quinasas Ciclina-Dependientes/antagonistas & inhibidores , Quinasas Ciclina-Dependientes/metabolismo , Interleucina-4/metabolismo , Quinasa 8 Dependiente de Ciclina/antagonistas & inhibidores , Quinasa 8 Dependiente de Ciclina/metabolismo , Inhibidores de Proteínas Quinasas/farmacología , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Fosforilación/efectos de los fármacos , Macrófagos Peritoneales/efectos de los fármacos , Macrófagos Peritoneales/metabolismo , Activación Enzimática/efectos de los fármacos , Flavonoides , Piperidinas , Quinasa 9 Dependiente de la Ciclina

RESUMEN

The eukaryotic Mediator, comprising a large Core (cMED) and a dissociable CDK8 kinase module (CKM), functions as a critical coregulator during RNA polymerase II (RNAPII) transcription. cMED recruits RNAPII and facilitates the assembly of the pre-initiation complex (PIC) at promoters. In contrast, CKM prevents RNAPII binding to cMED while simultaneously exerting positive or negative influence on gene transcription through its kinase function. Recent structural studies on cMED and CKM have revealed their intricate architectures and subunit interactions. Here, we explore these structures, providing a comprehensive insight into Mediator (cMED-CKM) architecture and its potential mechanism in regulating RNAPII transcription. Additionally, we discuss the remaining puzzles that require further investigation to fully understand how cMED coordinates with CKM to regulate transcription in various events.

Asunto(s)

Regulación de la Expresión Génica , Complejo Mediador , ARN Polimerasa II , Transcripción Genética , Complejo Mediador/metabolismo , Complejo Mediador/química , ARN Polimerasa II/metabolismo , ARN Polimerasa II/química , Humanos , Unión Proteica , Quinasa 8 Dependiente de Ciclina/metabolismo , Modelos Moleculares

RESUMEN

The essential Mediator (MED) coactivator complex plays a well-understood role in regulation of basal transcription in all eukaryotes, but the mechanism underlying its role in activator-dependent transcription remains unknown. We investigated modulation of metazoan MED interaction with RNA polymerase II (RNA Pol II) by antagonistic effects of the MED26 subunit and the CDK8 kinase module (CKM). Biochemical analysis of CKM-MED showed that the CKM blocks binding of the RNA Pol II carboxy-terminal domain (CTD), preventing RNA Pol II interaction. This restriction is eliminated by nuclear receptor (NR) binding to CKM-MED, which enables CTD binding in a MED26-dependent manner. Cryoelectron microscopy (cryo-EM) and crosslinking-mass spectrometry (XL-MS) revealed that the structural basis for modulation of CTD interaction with MED relates to a large intrinsically disordered region (IDR) in CKM subunit MED13 that blocks MED26 and CTD interaction with MED but is repositioned upon NR binding. Hence, NRs can control transcription initiation by priming CKM-MED for MED26-dependent RNA Pol II interaction.

Asunto(s)

Microscopía por Crioelectrón , Quinasa 8 Dependiente de Ciclina , Complejo Mediador , Unión Proteica , ARN Polimerasa II , ARN Polimerasa II/metabolismo , ARN Polimerasa II/genética , Complejo Mediador/metabolismo , Complejo Mediador/genética , Complejo Mediador/química , Humanos , Quinasa 8 Dependiente de Ciclina/metabolismo , Quinasa 8 Dependiente de Ciclina/genética , Animales , Proteínas Intrínsecamente Desordenadas/metabolismo , Proteínas Intrínsecamente Desordenadas/genética , Proteínas Intrínsecamente Desordenadas/química , Sitios de Unión , Receptores Citoplasmáticos y Nucleares/metabolismo , Receptores Citoplasmáticos y Nucleares/genética , Células HEK293 , Dominios y Motivos de Interacción de Proteínas

RESUMEN

Currently, the drugs used in clinical to treat psoriasis mainly broadly suppress cellular immunity. However, these drugs can only provide temporary and partial symptom relief, they do not cure the condition and may lead to recurrence or even serious toxic side effects. In this study, we describe the discovery of a novel potent CDK8 inhibitor as a treatment for psoriasis. Through structure-based design, compound 46 was identified as the most promising candidate, exhibiting a strong inhibitory effect on CDK8 (IC50 value of 57 nM) along with favourable inhibition against NF-κB. Additionally, it demonstrated a positive effect in an in vitro psoriasis model induced by TNF-α. Furthermore, this compound enhanced the thermal stability of CDK8 and exerted evident effects on the biological function of CDK8, and it had favourable selectivity across the CDK family and tyrosine kinase. This compound showed no obvious inhibitory effect on CYP450 enzyme. Further studies confirmed that compound 46 exhibited therapeutic effect on IMQ-induced psoriasis, alleviated the inflammatory response in mice, and enhanced the expression of Foxp3 and IL-10 in the dorsal skin in vivo. This discovery provides a new strategy for developing selective CDK8 inhibitors with anti-inflammatory activity for the treatment of psoriasis.

Asunto(s)

Quinasa 8 Dependiente de Ciclina , Inhibidores de Proteínas Quinasas , Psoriasis , Animales , Quinasa 8 Dependiente de Ciclina/antagonistas & inhibidores , Quinasa 8 Dependiente de Ciclina/metabolismo , Psoriasis/tratamiento farmacológico , Humanos , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/química , Ratones , FN-kappa B/metabolismo , FN-kappa B/antagonistas & inhibidores , Piridinas/farmacología , Piridinas/química , Ratones Endogámicos BALB C , Interleucina-10/metabolismo , Masculino , Pirroles/farmacología , Pirroles/química , Factores de Transcripción Forkhead/metabolismo , Descubrimiento de Drogas/métodos , Factor de Necrosis Tumoral alfa/metabolismo , Factor de Necrosis Tumoral alfa/antagonistas & inhibidores , Modelos Animales de Enfermedad , Piel/efectos de los fármacos , Piel/patología , Piel/metabolismo

RESUMEN

Dysregulation of cyclin-dependent kinase 8 (CDK8) activity has been associated with many diseases, including colorectal and breast cancer. As usual in the CDK family, the activity of CDK8 is controlled by a regulatory protein called cyclin C (CycC). But, while human CDK family members are generally activated in two steps, that is, the binding of the cyclin to CDK and the phosphorylation of a residue in the CDK activation loop, CDK8 does not require the phosphorylation step to be active. Another peculiarity of CDK8 is its ability to be associated with CycC while adopting an inactive form. These specificities raise the question of the role of CycC in the complex CDK8-CycC, which appears to be more complex than the other members of the CDK family. Through molecular dynamics (MD) simulations and binding free energy calculations, we investigated the effect of CycC on the structure and dynamics of CDK8. In a second step, we particularly focused our investigation on the structural and molecular basis of the protein-protein interaction between the two partners by finely analyzing the energetic contribution of residues and simulating the transition between the active and the inactive form. We found that CycC has a stabilizing effect on CDK8, and we identified specific interaction hotspots within its interaction surface compared to other human CDK/Cyc pairs. Targeting these specific interaction hotspots could be a promising approach in terms of specificity to effectively disrupt the interaction between CDK8. The simulation of the conformational transition from the inactive to the active form of CDK8 suggests that the residue Glu99 of CycC is involved in the orientation of three conserved arginines of CDK8. Thus, this residue may assume the role of the missing phosphorylation step in the activation mechanism of CDK8. In a more general view, these results point to the importance of keeping the CycC in computational studies when studying the human CDK8 protein in both the active and the inactive form.

Asunto(s)

Ciclina C , Quinasa 8 Dependiente de Ciclina , Simulación de Dinámica Molecular , Unión Proteica , Quinasa 8 Dependiente de Ciclina/metabolismo , Quinasa 8 Dependiente de Ciclina/química , Ciclina C/metabolismo , Ciclina C/química , Humanos , Fosforilación , Termodinámica , Sitios de Unión

RESUMEN

The identification of an effective inhibitor is an important starting step in drug development. Unfortunately, many issues such as the characterization of protein binding sites, the screening library, materials for assays, etc., make drug screening a difficult proposition. As the size of screening libraries increases, more resources will be inefficiently consumed. Thus, new strategies are needed to preprocess and focus a screening library towards a targeted protein. Herein, we report an ensemble machine learning (ML) model to generate a CDK8-focused screening library. The ensemble model consists of six different algorithms optimized for CDK8 inhibitor classification. The models were trained using a CDK8-specific fragment library along with molecules containing CDK8 activity. The optimized ensemble model processed a commercial library containing 1.6 million molecules. This resulted in a CDK8-focused screening library containing 1,672 molecules, a reduction of more than 99.90%. The CDK8-focused library was then subjected to molecular docking, and 25 candidate compounds were selected. Enzymatic assays confirmed six CDK8 inhibitors, with one compound producing an IC50 value of ≤100 nM. Analysis of the ensemble ML model reveals the role of the CDK8 fragment library during training. Structural analysis of molecules reveals the hit compounds to be structurally novel CDK8 inhibitors. Together, the results highlight a pipeline for curating a focused library for a specific protein target, such as CDK8.

Asunto(s)

Quinasa 8 Dependiente de Ciclina , Evaluación Preclínica de Medicamentos , Aprendizaje Automático , Inhibidores de Proteínas Quinasas , Humanos , Quinasa 8 Dependiente de Ciclina/antagonistas & inhibidores , Quinasa 8 Dependiente de Ciclina/química , Quinasa 8 Dependiente de Ciclina/metabolismo , Evaluación Preclínica de Medicamentos/métodos , Simulación del Acoplamiento Molecular , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/farmacología , Bibliotecas de Moléculas Pequeñas/química , Bibliotecas de Moléculas Pequeñas/farmacología

RESUMEN

The mediator kinases CDK8 and CDK19 control the dynamic transcription of selected genes in response to various signals and have been shown to be hijacked to sustain hyperproliferation by various solid and liquid tumors. CDK8/19 is emerging as a promising anticancer therapeutic target. Here, we report the discovery of compound 12, a novel small molecule CDK8/19 inhibitor. This molecule demonstrated not only decent enzymatic and cellular activities but also remarkable selectivity in CDK and kinome panels. Besides, compound 12 also displayed favorable ADME profiles including low CYP1A2 inhibition, acceptable clearance, and high oral bioavailability in multiple preclinical species. Robust in vivo PD and efficacy studies in mice models further demonstrated its potential use as mono- and combination therapy for the treatment of cancers.

Asunto(s)

Antineoplásicos , Quinasa 8 Dependiente de Ciclina , Quinasas Ciclina-Dependientes , Inhibidores de Proteínas Quinasas , Quinasa 8 Dependiente de Ciclina/antagonistas & inhibidores , Quinasa 8 Dependiente de Ciclina/metabolismo , Humanos , Animales , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/farmacocinética , Inhibidores de Proteínas Quinasas/uso terapéutico , Inhibidores de Proteínas Quinasas/síntesis química , Quinasas Ciclina-Dependientes/antagonistas & inhibidores , Quinasas Ciclina-Dependientes/metabolismo , Antineoplásicos/farmacología , Antineoplásicos/química , Antineoplásicos/farmacocinética , Antineoplásicos/uso terapéutico , Antineoplásicos/síntesis química , Ratones , Descubrimiento de Drogas , Línea Celular Tumoral , Relación Estructura-Actividad , Proliferación Celular/efectos de los fármacos , Neoplasias/tratamiento farmacológico , Ratas

RESUMEN

Cdk8 in Drosophila is the orthologue of vertebrate CDK8 and CDK19. These proteins have been shown to modulate transcriptional control by RNA polymerase II. We found that neuronal loss of Cdk8 severely reduces fly lifespan and causes bang sensitivity. Remarkably, these defects can be rescued by expression of human CDK19, found in the cytoplasm of neurons, suggesting a non-nuclear function of CDK19/Cdk8. Here we show that Cdk8 plays a critical role in the cytoplasm, with its loss causing elongated mitochondria in both muscles and neurons. We find that endogenous GFP-tagged Cdk8 can be found in both the cytoplasm and nucleus. We show that Cdk8 promotes the phosphorylation of Drp1 at S616, a protein required for mitochondrial fission. Interestingly, Pink1, a mitochondrial kinase implicated in Parkinson's disease, also phosphorylates Drp1 at the same residue. Indeed, overexpression of Cdk8 significantly suppresses the phenotypes observed in flies with low levels of Pink1, including elevated levels of ROS, mitochondrial dysmorphology, and behavioral defects. In summary, we propose that Pink1 and Cdk8 perform similar functions to promote Drp1-mediated fission.

Asunto(s)

Proteínas de Drosophila , Drosophila , Animales , Humanos , Fosforilación , Drosophila/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Dinámicas Mitocondriales/genética , Quinasas Ciclina-Dependientes/genética , Quinasas Ciclina-Dependientes/metabolismo , Quinasa 8 Dependiente de Ciclina/genética , Quinasa 8 Dependiente de Ciclina/metabolismo

RESUMEN

Mediator kinases CDK19 and CDK8, pleiotropic regulators of transcriptional reprogramming, are differentially regulated by androgen signaling, but both kinases are upregulated in castration-resistant prostate cancer (CRPC). Genetic or pharmacological inhibition of CDK8 and CDK19 reverses the castration-resistant phenotype and restores the sensitivity of CRPC xenografts to androgen deprivation in vivo. Prolonged CDK8/19 inhibitor treatment combined with castration not only suppressed the growth of CRPC xenografts but also induced tumor regression and cures. Transcriptomic analysis revealed that Mediator kinase inhibition amplified and modulated the effects of castration on gene expression, disrupting CRPC adaptation to androgen deprivation. Mediator kinase inactivation in tumor cells also affected stromal gene expression, indicating that Mediator kinase activity in CRPC molded the tumor microenvironment. The combination of castration and Mediator kinase inhibition downregulated the MYC pathway, and Mediator kinase inhibition suppressed a MYC-driven CRPC tumor model even without castration. CDK8/19 inhibitors showed efficacy in patient-derived xenograft models of CRPC, and a gene signature of Mediator kinase activity correlated with tumor progression and overall survival in clinical samples of metastatic CRPC. These results indicate that Mediator kinases mediated androgen-independent in vivo growth of CRPC, supporting the development of CDK8/19 inhibitors for the treatment of this presently incurable disease.

Asunto(s)

Quinasa 8 Dependiente de Ciclina , Quinasas Ciclina-Dependientes , Neoplasias de la Próstata Resistentes a la Castración , Inhibidores de Proteínas Quinasas , Ensayos Antitumor por Modelo de Xenoinjerto , Masculino , Humanos , Animales , Neoplasias de la Próstata Resistentes a la Castración/patología , Neoplasias de la Próstata Resistentes a la Castración/tratamiento farmacológico , Neoplasias de la Próstata Resistentes a la Castración/genética , Neoplasias de la Próstata Resistentes a la Castración/metabolismo , Neoplasias de la Próstata Resistentes a la Castración/enzimología , Ratones , Quinasas Ciclina-Dependientes/antagonistas & inhibidores , Quinasas Ciclina-Dependientes/genética , Quinasas Ciclina-Dependientes/metabolismo , Quinasa 8 Dependiente de Ciclina/antagonistas & inhibidores , Quinasa 8 Dependiente de Ciclina/genética , Quinasa 8 Dependiente de Ciclina/metabolismo , Línea Celular Tumoral , Inhibidores de Proteínas Quinasas/farmacología , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Microambiente Tumoral/efectos de los fármacos

RESUMEN

Pulmonary fibrosis involves destruction of the lung parenchyma and extracellular matrix deposition. Effective treatments for pulmonary fibrosis are lacking and its pathogenesis is still unclear. Studies have found that epithelial-mesenchymal transition (EMT) of alveolar epithelial cells (AECs) plays an important role in progression of pulmonary fibrosis. Thus, an in-depth exploration of its mechanism might identify new therapeutic targets. In this study, we revealed that a novel circular RNA, MKLN1 (circMKLN1), was significantly elevated in two pulmonary fibrosis models (intraperitoneally with PQ, 50 mg/kg for 7 days, and intratracheally with BLM, 5 mg/kg for 28 days). Additionally, circMKLN1 was positively correlated with the severity of pulmonary fibrosis. Inhibition of circMKLN1 expression significantly reduced collagen deposition and inhibited EMT in AECs. EMT was aggravated after circMKLN1 overexpression in AECs. MiR-26a-5p/miR-26b-5p (miR-26a/b), the targets of circMKLN1, were confirmed by luciferase reporter assays. CircMKLN1 inhibition elevated miR-26a/b expression. Significantly decreased expression of CDK8 (one of the miR-26a/b targets) was observed after inhibition of circMKLN1. EMT was exacerbated again, and CDK8 expression was significantly increased after circMKLN1 inhibition and cotransfection of miR-26a/b inhibitors in AECs. Our research indicated that circMKLN1 promoted CDK8 expression through sponge adsorption of miR-26a/b, which regulates EMT and pulmonary fibrosis. This study provides a theoretical basis for finding new targets or biomarkers in pulmonary fibrosis.

Asunto(s)

MicroARNs , Fibrosis Pulmonar , Humanos , Ratones , Animales , Fibrosis Pulmonar/inducido químicamente , Fibrosis Pulmonar/genética , MicroARNs/genética , MicroARNs/metabolismo , ARN Circular/genética , Células Epiteliales Alveolares , Transición Epitelial-Mesenquimal/genética , Quinasa 8 Dependiente de Ciclina/metabolismo , Moléculas de Adhesión Celular/metabolismo , Péptidos y Proteínas de Señalización Intracelular/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo

RESUMEN

Pollen development in flowering plants has strong implications for reproductive success. Pollen DNA can be targeted to improve plant traits for yield and stress tolerance. In this study, we demonstrated that the Mediator subunit CYCLIN-DEPENDENT KINASE 8 (CDK8) is a key modulator of pollen development in tomato (Solanum lycopersicum). SlCDK8 knockout led to significant decreases in pollen viability, fruit yield, and fruit seed number. We also found that SlCDK8 directly interacts with transcription factor TEOSINTE BRANCHED1-CYCLOIDEA-PCF15 (SlTCP15) using yeast two-hybrid screens. We subsequently showed that SlCDK8 phosphorylates Ser 187 of SlTCP15 to promote SlTCP15 stability. Phosphorylated TCP15 directly bound to the TGGGCY sequence in the promoters of DYSFUNCTIONAL TAPETUM 1 (SlDYT1) and MYB DOMAIN PROTEIN 103 (SlMYB103), which are responsible for pollen development. Consistently, disruption of SlTCP15 resembled slcdk8 tomato mutants. In sum, our work identified a new substrate of Mediator CDK8 and revealed an important regulatory role of SlCDK8 in pollen development via cooperation with SlTCP15.

Asunto(s)

Quinasa 8 Dependiente de Ciclina , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas , Polen , Solanum lycopersicum , Factores de Transcripción , Solanum lycopersicum/genética , Solanum lycopersicum/crecimiento & desarrollo , Solanum lycopersicum/metabolismo , Polen/crecimiento & desarrollo , Polen/genética , Polen/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Quinasa 8 Dependiente de Ciclina/metabolismo , Quinasa 8 Dependiente de Ciclina/genética , Factores de Transcripción/metabolismo , Factores de Transcripción/genética , Fosforilación , Mutación/genética

RESUMEN

Plants are often exposed to recurring adverse environmental conditions in the wild. Acclimation to high temperatures entails transcriptional responses, which prime plants to better withstand subsequent stress events. Heat stress (HS)-induced transcriptional memory results in more efficient re-induction of transcription upon recurrence of heat stress. Here, we identified CDK8 and MED12, two subunits of the kinase module of the transcription co-regulator complex, Mediator, as promoters of heat stress memory and associated histone modifications in Arabidopsis. CDK8 is recruited to heat-stress memory genes by HEAT SHOCK TRANSCRIPTION FACTOR A2 (HSFA2). Like HSFA2, CDK8 is largely dispensable for the initial gene induction upon HS, and its function in transcriptional memory is thus independent of primary gene activation. In addition to the promoter and transcriptional start region of target genes, CDK8 also binds their 3'-region, where it may promote elongation, termination, or rapid re-initiation of RNA polymerase II (Pol II) complexes during transcriptional memory bursts. Our work presents a complex role for the Mediator kinase module during transcriptional memory in multicellular eukaryotes, through interactions with transcription factors, chromatin modifications, and promotion of Pol II efficiency.

Asunto(s)

Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Respuesta al Choque Térmico/genética , Factores de Transcripción del Choque Térmico/metabolismo , Activación Transcripcional , Nucleotidiltransferasas/metabolismo , Complejo Mediador/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Quinasa 8 Dependiente de Ciclina/genética , Quinasa 8 Dependiente de Ciclina/metabolismo

RESUMEN

Neurological diseases, including traumatic brain injuries, stroke (haemorrhagic and ischemic), and inherent neurodegenerative diseases cause acquired disability in humans, representing a leading cause of death worldwide. The Mediator complex (MED) is a large, evolutionarily conserved multiprotein that facilities the interaction between transcription factors and RNA Polymerase II in eukaryotes. Some MED subunits have been found altered in the brain, although their specific functions in neurodegenerative diseases are not fully understood. Mutations in MED subunits were associated with a wide range of genetic diseases for MED12, MED13, MED13L, MED20, MED23, MED25, and CDK8 genes. In addition, MED12 and MED23 were deregulated in the Alzheimer's Disease. Interestingly, most of the genomic mutations have been found in the subunits of the kinase module. To date, there is only one evidence on MED1 involvement in post-stroke cognitive deficits. Although the underlying neurodegenerative disorders may be different, we are confident that the signal cascades of the biological-cognitive mechanisms of brain adaptation, which begin after brain deterioration, may also differ. Here, we analysed relevant studies in English published up to June 2023. They were identified through a search of electronic databases including PubMed, Medline, EMBASE and Scopus, including search terms such as "Mediator complex", "neurological disease", "brains". Thematic content analysis was conducted to collect and summarize all studies demonstrating MED alteration to understand the role of this central transcriptional regulatory complex in the brain. Improved and deeper knowledge of the regulatory mechanisms in neurological diseases can increase the ability of physicians to predict onset and progression, thereby improving diagnostic care and providing appropriate treatment decisions.

Asunto(s)

Quinasa 8 Dependiente de Ciclina , Factores de Transcripción , Humanos , Quinasa 8 Dependiente de Ciclina/genética , Quinasa 8 Dependiente de Ciclina/metabolismo , Factores de Transcripción/metabolismo , Mutación , Complejo Mediador/genética

RESUMEN

Fibroblasts can be chemically induced to pluripotent stem cells (CiPSCs) through an extraembryonic endoderm (XEN)-like state or directly converted into other differentiated cell lineages. However, the mechanisms underlying chemically induced cell-fate reprogramming remain unclear. Here, a transcriptome-based screen of biologically active compounds uncovered that CDK8 inhibition was essential to enable chemically induced reprogramming from fibroblasts into XEN-like cells, then CiPSCs. RNA-sequencing analysis showed that CDK8 inhibition downregulated proinflammatory pathways that suppress chemical reprogramming and facilitated the induction of a multi-lineage priming state, indicating the establishment of plasticity in fibroblasts. CDK8 inhibition also resulted in a chromatin accessibility profile like that under initial chemical reprogramming. Moreover, CDK8 inhibition greatly promoted reprogramming of mouse fibroblasts into hepatocyte-like cells and induction of human fibroblasts into adipocytes. These collective findings thus highlight CDK8 as a general molecular barrier in multiple cell reprogramming processes, and as a common target for inducing plasticity and cell fate conversion.

Asunto(s)

Quinasa 8 Dependiente de Ciclina , Células Madre Pluripotentes Inducidas , Células Madre Pluripotentes , Animales , Humanos , Ratones , Diferenciación Celular , Reprogramación Celular/genética , Quinasa 8 Dependiente de Ciclina/genética , Quinasa 8 Dependiente de Ciclina/metabolismo , Fibroblastos/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , Células Madre Pluripotentes/metabolismo , Transcriptoma/genética

RESUMEN

The CDK8-cyclin C complex is an important anti-tumor target, but unlike CDK8, cyclin C remains undruggable. Modulators regulating cyclin C activity directly are still under development. Here, a series of hydrophobic tagging-based degraders of the CDK8-cyclin C complex were designed, synthesized, and evaluated to identify the first dual degrader, LL-K8-22, which induced selective and synchronous degradation of CDK8 and cyclin C. Proteomic and immunoblot studies exhibited that LL-K8-22 significantly degraded CDK8 without reducing CDK19 and did not degrade other cyclin proteins except cyclin C. Moreover, LL-K8-22 showed enhanced anti-proliferative effects over its parental molecule, BI-1347, with potency increased by 5-fold in MDA-MB-468 cells. LL-K8-22 exhibited more pronounced effects on CDK8-cyclin C downstream signaling than BI-1347, suppressing STAT1 phosphorylation more persistently. RNA-sequencing analysis revealed that LL-K8-22 inhibited E2F- and MYC-driven carcinogenic transcriptional programs. Overall, LL-K8-22 is the first-in-class degrader of cyclin C and would be useful for studying the unknown functions of cyclin C.

Asunto(s)

Ciclina C , Quinasas Ciclina-Dependientes , Ciclina C/metabolismo , Quinasa 8 Dependiente de Ciclina/metabolismo , Quinasas Ciclina-Dependientes/metabolismo , Fosforilación , Proteómica , Transducción de Señal

RESUMEN

BACKGROUND: Chronic inflammation is a well-known risk factor for the development of gastric cancer (GC). Nevertheless, the molecular mechanisms underlying inflammation-related GC progression are incompletely defined. METHODS: Bioinformatic analysis was performed based on data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO), and the expression of miR-26b-5p in GC cells and tissues was validated by quantitative real-time PCR (qRT-PCR). Cell proliferation was examined through Cell Counting Kit-8 (CCK8), 5-Ethynyl-2'-deoxyuridine (EdU), colony formation, flow cytometry, and tumor xenografts. Correlation between miR-26b-5p and Cyclin dependent kinase 8 (CDK8) or Phosphodiesterase 4B (PDE4B) was analyzed by dual-luciferase reporter assays, qRT-PCR, and Western blot. The effect of miR-26b-5p on the Signal transducer and activator of transcription 3 (STAT3) pathway was investigated using Western blot, immunofluorescence (IF), and immunohistochemistry (IHC). The impact of STAT3 on miR-26b-5p was determined by dual-luciferase reporter assays and qRT-PCR. RESULTS: The expression of miR-26b-5p was significantly downregulated in Helicobacter Pylori (H. pylori)-infected GC cells. The decreased expression of miR-26b-5p was also detected in GC cells and tissues compared to normal gastric epithelium cells (GES1) and normal adjacent gastric tissues. The low expression of miR-26b-5p promoted GC proliferation in vitro and in vivo and was related to the poor outcome of GC patients. In terms of mechanism, miR-26b-5p directly targeted PDE4B and CDK8, resulting in decreased phosphorylation and nuclear translocation of STAT3, which was associated with the regulation of GC proliferation by miR-26b-5p. Notably, miR-26b-5p was transcriptionally suppressed by STAT3, thus forming the miR-26b-5p-PDE4B/CDK8-STAT3 positive feedback loop. CONCLUSION: The newly identified miR-26b-5p-PDE4B/CDK8-STAT3 feedback loop plays an important role in inflammation-related GC progression and may serve as a promising therapeutic target for GC.

Asunto(s)

MicroARNs , Neoplasias Gástricas , Humanos , Línea Celular Tumoral , Proliferación Celular/genética , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 4/genética , Fosfodiesterasas de Nucleótidos Cíclicos Tipo 4/metabolismo , Quinasa 8 Dependiente de Ciclina/genética , Quinasa 8 Dependiente de Ciclina/metabolismo , Retroalimentación , Regulación Neoplásica de la Expresión Génica , MicroARNs/genética , MicroARNs/metabolismo , Factor de Transcripción STAT3/metabolismo , Neoplasias Gástricas/patología , Animales

RESUMEN

CYCLIN-DEPENDENT KINASE 8 (CDK8), a component of the kinase module of the Mediator complex in Arabidopsis, is involved in many processes, including flowering, plant defense, drought, and energy stress responses. Here, we investigated cdk8 mutants and CDK8-overexpressing lines to evaluate whether CDK8 also plays a role in regulating lipid synthesis, an energy-demanding anabolism. Quantitative lipid analysis demonstrated significant reductions in lipid synthesis rates and lipid accumulation in developing siliques and seedlings of cdk8, and conversely, elevated lipid contents in wild-type seed overexpressing CDK8. Transactivation assays show that CDK8 is necessary for maximal transactivation of the master seed oil activator WRINKLED1 (WRI1) by the seed maturation transcription factor ABSCISIC ACID INSENSITIVE3, supporting a direct regulatory role of CDK8 in oil synthesis. Thermophoretic studies show GEMINIVIRUS REP INTERACTING KINASE1, an activating kinase of KIN10 (a catalytic subunit of SUCROSE NON-FERMENTING1-RELATED KINASE1), physically interacts with CDK8, resulting in its phosphorylation and degradation in the presence of KIN10. This work defines a mechanism whereby, once activated, KIN10 downregulates WRI1 expression and suppresses lipid synthesis via promoting the degradation of CDK8. The KIN10-CDK8-dependent regulation of lipid synthesis described herein is additional to our previously reported KIN10-dependent phosphorylation and degradation of WRI1.

Asunto(s)

Proteínas de Arabidopsis , Arabidopsis , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Quinasa 8 Dependiente de Ciclina/metabolismo , Arabidopsis/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Lípidos