Familial Dilated Cardiomyopathy: A Novel MED9 Short Isoform Identification.

Familial dilated cardiomyopathy (DCM) is among the leading indications for heart transplantation. DCM alters the transcriptomic profile. The alteration or activation/silencing of physiologically operating transcripts may explain the onset and progression of this pathological state. The mediator complex (MED) plays a fundamental role in the transcription process. The aim of this study is to investigate the MED subunits, which are altered in DCM, to identify target crossroads genes. RNA sequencing allowed us to identify specific MED subunits that are altered during familial DCM, transforming into human myocardial samples. N = 13 MED subunits were upregulated and n = 7 downregulated. MED9 alone was significantly reduced in patients compared to healthy subjects (HS) (FC = -1.257; p < 0.05). Interestingly, we found a short MED9 isoform (MED9s) (ENSG00000141026.6), which was upregulated when compared to the full-transcript isoform (MED9f). Motif identification analysis yielded several significant matches (p < 0.05), such as GATA4, which is downregulated in CHD. Moreover, although the protein-protein interaction network showed FOG2/ZFPM2, FOS and ID2 proteins to be the key interacting partners of GATA4, only FOG2/ZFPM2 overexpression showed an interaction score of "high confidence" ≥ 0.84. A significant change in the MED was observed during HF. For the first time, the MED9 subunit was significantly reduced between familial DCM and HS (p < 0.05), showing an increased MED9s isoform in DCM patients with respect to its full-length transcript. MED9 and GATA4 shared the same sequence motif and were involved in a network with FOG2/ZFPM2, FOS, and ID2, proteins already implicated in cardiac development.

Cochleovestibular Phenotype in a Rare Genetic MED13L Mutation.

The gene MED13 participates in transcription. The MED13L gene is a paralog of MED13 that is involved in developmental gene expression. Mutations in the gene have been shown to result in a heterogenous phenotype affecting several physiological systems. Hearing loss has been reported very rarely, and vestibular weakness has never been reported in the condition. In this report, we present a mutation of MED13L in c.1162A > T (p.Arg388Ter), where we detail and describe a cochleovestibular phenotype with objective vestibulometry for the first time. The child showed bilateral sloping sensorineural hearing loss, a bilateral vestibular weakness, and an inner ear vestibular structural abnormality on imaging. Early intervention with hearing aids and vestibular rehabilitation led to a favorable outcome in terms of speech, communication, and balance. We emphasize the importance of comprehensive audiovestibular assessment in children diagnosed with MED13L mutations for effective management of these children.

Assessment of machine-learning predictions for the Mediator complex subunit MED25 ACID domain interactions with transactivation domains.

The human Mediator complex subunit MED25 binds transactivation domains (TADs) present in various cellular and viral proteins using two binding interfaces, named H1 and H2, which are found on opposite sides of its ACID domain. Here, we use and compare deep learning methods to characterize human MED25-TAD interfaces and assess the predicted models to published experimental data. For the H1 interface, AlphaFold produces predictions with high-reliability scores that agree well with experimental data, while the H2 interface predictions appear inconsistent, preventing reliable binding modes. Despite these limitations, we experimentally assess the validity of MED25 interface predictions with the viral transcriptional activators Lana-1 and IE62. AlphaFold predictions also suggest the existence of a unique hydrophobic pocket for the Arabidopsis MED25 ACID domain.

Comparative phylogenetic analysis of the mediator complex subunit in asparagus bean (Vigna unguiculata ssp. sesquipedialis) and its expression profile under cold stress.

BACKGROUND: The mediator complex subunits (MED) constitutes a multiprotein complex, with each subunit intricately involved in crucial aspects of plant growth, development, and responses to stress. Nevertheless, scant reports pertain to the VunMED gene within the context of asparagus bean (Vigna unguiculata ssp. sesquipedialis). Establishing the identification and exploring the responsiveness of VunMED to cold stress forms a robust foundation for the cultivation of cold-tolerant asparagus bean cultivars. RESULTS: Within this study, a comprehensive genome-wide identification of VunMED genes was executed in the asparagus bean cultivar 'Ningjiang3', resulting in the discovery of 36 distinct VunMED genes. A phylogenetic analysis encompassing 232 MED genes from diverse species, including Arabidopsis, tomatoes, soybeans, mung beans, cowpeas, and asparagus beans, underscored the highly conserved nature of MED gene sequences. Throughout evolutionary processes, each VunMED gene underwent purification and neutral selection, with the exception of VunMED19a. Notably, VunMED9/10b/12/13/17/23 exhibited structural variations discernible across four cowpea species. Divergent patterns of temporal and spatial expression were evident among VunMED genes, with a prominent role attributed to most genes during early fruit development. Additionally, an analysis of promoter cis-acting elements was performed, followed by qRT-PCR assessments on roots, stems, and leaves to gauge relative expression after exposure to cold stress and subsequent recovery. Both treatments induced transcriptional alterations in VunMED genes, with particularly pronounced effects observed in root-based genes following cold stress. Elucidating the interrelationships between subunits involved a preliminary understanding facilitated by correlation and principal component analyses. CONCLUSIONS: This study elucidates the pivotal contribution of VunMED genes to the growth, development, and response to cold stress in asparagus beans. Furthermore, it offers a valuable point of reference regarding the individual roles of MED subunits.

Hypoxic Bone Mesenchymal Stem Cell-Derived Exosomes Direct Schwann Cells Proliferation, Migration, and Paracrine to Accelerate Facial Nerve Regeneration via circRNA_Nkd2/miR-214-3p/MED19 Axis.

Background: Facial nerves have the potential for regeneration following injury, but this process is often challenging and slow. Schwann cells (SCs) are pivotal in this process. Bone mesenchymal stem cells (BMSC)-derived exosomes promote tissue repair through paracrine action, with hypoxic preconditioning enhancing their effects. The main purpose of this study was to determine whether hypoxia-preconditioned BMSC-derived exosomes (Hypo-Exos) exhibit a greater therapeutic effect on facial nerve repair/regeneration and reveal the mechanism. Methods: CCK-8, EdU, Transwell, and ELISA assays were used to evaluate the functions of Hypo-Exos in SCs. Histological analysis and Vibrissae Movements (VMs) recovery were used to evaluate the therapeutic effects of Hypo-Exos in rat model. circRNA array was used to identify the significantly differentially expressed exosomal circRNAs between normoxia-preconditioned BMSC-derived exosomes (Nor-Exos) and Hypo-Exos. miRDB, TargetScan, double luciferase assay, qRT-PCR and WB were used to predict and identify potential exosomal cirRNA_Nkd2-complementary miRNAs and its target gene. The function of exosomal circRNA_Nkd2 in facial nerve repair/regeneration was evaluated by cell and animal experiments. Results: This study confirmed that Hypo-Exos more effectively promote SCs proliferation, migration, and paracrine function, accelerating facial nerve repair following facial nerve injury (FNI) compared with Nor-Exos. Furthermore, circRNA analysis identified significant enrichment of circRNA_Nkd2 in Hypo-Exos compared with Nor-Exos. Exosomal circRNA_Nkd2 positively regulates mediator complex subunit 19 (MED19) expression by sponging rno-miR-214-3p. Conclusion: Our results demonstrated a mechanism by which Hypo-Exos enhanced SCs proliferation, migration, and paracrine function and facial nerve repair and regeneration following FNI through the circRNA_Nkd2/miR-214-3p/Med19 axis. Hypoxic preconditioning is an effective and promising method for optimizing the therapeutic action of BMSC-derived exosomes in FNI.

Expanding the phenotypic spectrum for CDK8-related disease: A case report.

BACKGROUND: Cyclin-dependent kinase 8 (CDK8) is part of a regulatory kinase module that regulates the activity of the Mediator complex. The Mediator, a large conformationally flexible protein complex, goes on to regulate RNA polymerase II activity, consequently affecting transcriptional regulation. Thus, inactivating mutations of the genes within the kinase module cause aberrant transcriptional regulation and disease, namely, CDK8-related intellectual developmental disorder with hypotonia and behavioral abnormalities (IDDHBA). CASE PRESENTATION: We describe, for the first time, a likely pathogenic heterozygous CDK8 variant c.599G>A, p.(Arg200Gln) inherited from the biological mother. The clinical presentation of the child and mother is within the described clinical spectrum for IDDHBA; however, undocumented progressive contractures of the hips and knees as well as scoliosis were also observed in the child. This phenotype was not found in the mother, highlighting a heterogenous presentation for the same variant within the same family. Furthermore, the described clinical presentation may further support the notion of a module- or Mediator-related syndrome with varying clinical presentation. CONCLUSION: This case report documents the first inherited case of IDDHBA and expands the phenotypic spectrum for CDK8-related disease to include undocumented progressive contractures of the hips and knees as well as scoliosis, which may support the notion of a module- or Mediator-related syndrome with varying clinical presentation.

The Effect of Race/Ethnicity and MED12 Mutation on the Expression of Long Non-Coding RNAs in Uterine Leiomyoma and Myometrium.

The objective of this study was to elucidate the expression of long non-coding RNA (lncRNA) in leiomyomas (Lyo) and paired myometrium (Myo) and explore the impact of race and MED12 mutation. Fold change analysis (Lyo/paired Myo) indicated the expression of 63 lncRNAs was significantly altered in the mutated group but not in the non-mutated Lyo. Additionally, 65 lncRNAs exhibited an over 1.5-fold change in the Black but not the White group. Fifteen differentially expressed lncRNAs identified with next-generation sequencing underwent qRT-PCR confirmation. Compared with Myo, the expression of TPTEP1, PART1, RPS10P7, MSC-AS1, SNHG12, CA3-AS1, LINC00337, LINC00536, LINC01436, LINC01449, LINC02433, and LINC02624 was significantly higher, while the expression of ZEB2-AS1, LINC00957, and LINC01186 was significantly lower. Comparison of normal Myo with diseased Myo showed significant differences in the expression of several lncRNAs. Analysis based on race and Lyo MED12 mutation status indicated a significantly higher expression of RPS10P7, SNHG12, LINC01449, LINC02433, and LINC02624 in Lyo from Black patients. The expression of TPTEP1, PART1, RPS10P7, MSC-AS1, LINC00337, LINC00536, LINC01436, LINC01449, LINC02433, and LINC02624 was higher, while LINC01186 was significantly lower in the MED12-mutated group. These results indicate that Lyo are characterized by aberrant lncRNA expression, which is further impacted by race and Lyo MED12 mutation status.

Med23 deficiency reprograms the tumor microenvironment to promote lung tumorigenesis.

BACKGROUND: Lung cancer is the leading cause of cancer-related death worldwide. We previously found that Mediator complex subunit 23 (MED23) is important for the tumourigenicity of lung cancer cells with hyperactive Ras activity in vitro, although the in vivo function of MED23 in lung tumourigenesis remains to be explored. METHODS: In this study, we utilized well-characterized KrasG12D-driven non-small cell lung cancer mouse model to investigate the role of MED23 in lung cancer. The lung tumour progression was evaluated by H&E and IHC analysis. Western blotting and qRT-PCR assays were performed to detect changes in gene expression. Immune cells were analyzed by FACS technology. RNA-seq and reporter assays were conducted to explore the mechanism. RESULTS: We observed that lung epithelial Med23 deletion by adeno-Cre resulted in a significant increase in KrasG12D tumour number and size, which was further verified with another mouse model with Med23 specifically deleted in alveolar type II cells. Mice with lung-specific Med23 deficiency also exhibited accelerated tumourigenesis, and a higher proliferation rate for tumour cells, along with increased ERK phosphorylation. Notably, the numbers of infiltrating CD4+ T cells and CD8+ T cells were significantly reduced in the lungs of Med23-deficient mice, while the numbers of myeloid-derived suppressor cells (MDSCs) and Treg cells were significantly increased, suggesting the enhanced immune escape capability of the Med23-deficient lung tumours. Transcriptomic analysis revealed that the downregulated genes in Med23-deficient lung tumour tissues were associated with the immune response. Specifically, Med23 deficiency may compromise the MHC-I complex formation, partially through down-regulating B2m expression. CONCLUSIONS: Collectively, these findings revealed that MED23 may negatively regulate Kras-induced lung tumourigenesis in vivo, which would improve the precise classification of KRAS-mutant lung cancer patients and provide new insights for clinical interventions.

The Mediator kinase module enhances polymerase activity to regulate transcriptional memory after heat stress in Arabidopsis.

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.

Three-dimensional chromatin landscapes in hepatocellular carcinoma associated with hepatitis B virus.

BACKGROUND: Three-dimensional (3D) chromatin architecture frequently altered in cancer. However, its changes during the pathogenesis of hepatocellular carcinoma (HCC) remained elusive. METHODS: Hi-C and RNA-seq were applied to study the 3D chromatin landscapes and gene expression of HCC and ANHT. Hi-C Pro was used to generate genome-wide raw interaction matrices, which were normalized via iterative correction (ICE). Moreover, the chromosomes were divided into different compartments according to the first principal component (E1). Furthermore, topologically associated domains (TADs) were visualized via WashU Epigenome Browser. Furthermore, differential expression analysis of ANHT and HCC was performed using the DESeq2 R package. Additionally, dysregulated genes associated with 3D genome architecture altered were confirmed using TCGA, qRT-PCR, immunohistochemistry (IHC), etc. RESULTS: First, the intrachromosomal interactions of chr1, chr2, chr5, and chr11 were significantly different, and the interchromosomal interactions of chr4-chr10, chr13-chr21, chr15-chr22, and chr16-chr19 are remarkably different between ANHT and HCC, which resulted in the up-regulation of TP53I3 and ZNF738 and the down-regulation of APOC3 and APOA5 in HCC. Second, 49 compartment regions on 18 chromosomes have significantly switched (A-B or B-A) during HCC tumorigenesis, contributing to up-regulation of RAP2A. Finally, a tumor-specific TAD boundary located on chr5: 6271000-6478000 and enhancer hijacking were identified in HCC tissues, potentially associated with the elevated expression of MED10, whose expression were associated with poor prognosis of HCC patients. CONCLUSION: This study demonstrates the crucial role of chromosomal structure variation in HCC oncogenesis and potential novel biomarkers of HCC, laying a foundation for cancer precision medicine development.

The Mediator Complex Subunit 12 (MED-12) Gene and Uterine Fibroids: a Systematic Review.

Uterine leiomyomas are the most common tumor of reproductive-age women worldwide. Although benign, uterine fibroids cause significant morbidity and adversely impact the quality of life for affected women. Somatic mutations in the exon 2 of the mediator complex subunit 12 (MED-12) gene represent the most common single gene mutation associated with uterine leiomyomas. The objective of this review was to evaluate the current role of MED-12 mutation in the pathophysiology of uterine fibroids, to assess the prevalence of MED-12 mutation among different populations, and to identify the most common subtypes of MED-12 mutations found in uterine fibroids. A comprehensive search was conducted using Pubmed, Embase, Scopus, and the Web of Science. English-language publications that evaluated MED-12 mutation and uterine fibroids in humans, whether experimental or clinical, were considered. We identified 380 studies, of which 23 were included, comprising 1353 patients and 1872 fibroid tumors. Of the total number of tumors analyzed, 1045 (55.8%) harbored a MED-12 mutation. Among the 23 studies included, the frequency of MED-12 mutation varied from 31.1 to 80% in fibroid samples. The most common type of MED-12 mutation was a heterozygous missense mutation affecting codon 44 of exon 2, specifically the nucleotide 131. Studies reported that MED-12 mutation acts by increasing levels of AKT and disrupting the cyclin C-CDK8/19 kinase activity. The overall average prevalence of MED-12 mutation in uterine fibroids was found to be 55.8% across the global population, though the frequency varied greatly among different countries.

Chloroprocaine antagonizes progression of breast cancer by regulating LINC00494/miR-3619-5p/MED19 axis.

Breast cancer, as the most prevalent female malignancy, leads the cancer-related death in women worldwide. Local anesthetic chloroprocaine exhibits antitumor potential, but its specific functions and underlying molecular mechanisms in breast cancer remain unclear. Here, we demonstrated chloroprocaine significantly inhibited proliferation, invasion and induced apoptosis of breast cancer cells in vitro. Tumor growth and pulmonary metastasis were also suppressed in BABL/c nude mice model with chloroprocaine treatment. LINC00494 was identified as one of the most downregulated long noncoding RNAs in chloroprocaine-treated breast cancer cells by high-throughput sequencing. Futhermore, high level of LINC00494 was positively associated with poor outcome of breast cancer patients. LINC00494 acted as a "miRNAs sponge" to compete with MED19 for the biding of miR-3619-5p, led to the upregulation of MED19. LINC00494/miR-3619-5p/MED19 axis participated in chloroprocaine-mediated inhibition of proliferation, invasion and promotion of apoptosis of breast cancer cells. Consequently, our finding suggested local anesthetic chloroprocaine attenuated breast cancer aggressiveness through LINC00494-mediated signaling pathway, which detailly revealed the clinical value of chloroprocaine during breast cancer treatment.

Are both distinct epithelial and stromal cells molecular analysis from phyllodes tumors versus fibroadenoma components affected in breast fibroepithelial progression?

PURPOSE: To determine molecular events involved in the tumorigenesis of phyllodes tumors (PT) and the role of each stromal (SC) and epithelial (EC) cell. METHODS: Frozen breast samples enriched with epithelial and stromal cells from three fibroadenomas and 14 PT were retrieved and laser microdissected. Sanger and polymerase chain reaction-based sequencing of exon 2 MED12 and TERT promoter hotspot mutations were performed; 44K microarray platform was used to analyze gene expression. RESULTS: All three fibroadenomas (FAs) presented mutations in MED12, but not in TERT, whose mutation was observed in five of the 14 PTs. EC and SC of each affected tumor displayed identical alterations. Of the total differentially expressed genes (DEG) (EC = 1,543 and SC = 850), 984 were EC-eDEGs and 291 were SC-eDEGs. We found a high similarity of diseases and functions enriched by both cell types, but dissimilarity in the number of enriched canonical pathways. Three signaling canonical pathways overlapping with EC and SC were predicted to be activated in one cell type and inactivated in the other, while no overlap in eDEGs was assigned to them. We also identified 13 EC-eDEGs and five SC-eDEGs enriched networks, in which the SC-eDEGs were able to segregate FA from PT samples. CONCLUSIONS: Identical TERT mutations from both SC and ES origins might affect the PTs tumorigenesis. Gene expression differences suggest coordinated molecular processes between these components with determinant differences acquired by SC, able to fully distinguish PTs from FAs lesions.

Upregulation of MED7 was associated with progression in hepatocellular carcinoma.

OBJECTIVE: MED subunits have been reported to be associated with various types of tumors, however, the potential role of MED7 in hepatocellular carcinoma (HCC) was still unclear. The aim of the study was to explore the role of MED7 in HCC. METHODS: In this study, MED7 mRNA expression levels between HCC and adjacent normal tissues were first analyzed by several public datasets. Then we utilized a tissue microarray (TMA) to investigate the clinical role of MED7 in HCC by immunohistochemistry (IHC). Meanwhile, the potential mechanisms of MED7 based on gene-gene correlation analyses were also explored. RESULTS: High mRNA level of MED7 correlated with advanced stage and worse grade of differentiation. IHC results showed that MED7 protein level was upregulated in HCC and associated with Edmondson grade and Microvascular invasion in 330 cases of HCC. GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis revealed that MED7 co-expressed genes participate primarily in ribonucleoprotein complex biogenesis, protein targeting, mRNA processing and nucleoside triphosphate metabolic process et cetera. Further analysis also revealed that MED7 mRNA level has significant correlation with immune cells infiltration levels. CONCLUSION: MED7 was upregulated in HCC and correlated with progression of HCC. Meanwhile, MED7 may promote HCC through participating in multiple gene networks to influence tumorigenesis as well as immune response in HCC microenvironment.

Novel pathogenic variant in MED12 causing non-syndromic dilated cardiomyopathy.

BACKGROUND: Dilated cardiomyopathy (DCM) is a major cause of sudden cardiac death and heart failure. Up to 50% of all DCM cases have a genetic background, with variants in over 250 genes reported in association with DCM. Whole-exome sequencing (WES) is a powerful tool to identify variants underlying genetic cardiomyopathies. Via WES, we sought to identify DCM causes in a family with 2 affected patients. METHODS: WES was performed on the affected members of an Iranian family to identify the genetic etiology of DCM. The candidate variant was segregated via polymerase chain reaction and Sanger sequencing. Computational modeling and protein-protein docking were performed to survey the impact of the variant on the structure and function of the protein. RESULTS: A novel single-nucleotide substitution (G > A) in exon 9 of MED12, c.1249G > A: p.Val417Ile, NM_005120.3, was identified. The c.1249G > A variant was validated in the family. Bioinformatic analysis and computational modeling confirmed that c.1249G > A was the pathogenic variant responsible for the DCM phenotype. CONCLUSION: We detected a novel DCM-causing variant in MED12 using WES. The variant in MED12 may decrease binding to cyclin-dependent kinase 8 (CDK8), affect its activation, and cause alterations in calcium-handling gene expression in the heart, leading to DCM.

Regulation of fungal raw-starch-degrading enzyme production depends on transcription factor phosphorylation and recruitment of the Mediator complex.

Filamentous fungus can produce raw-starch-degrading enzyme (RSDE) that efficiently degrades raw starch below starch gelatinization temperature. Employment of RSDE in starch processing can save energy. A key putative transcription factor PoxRsrA (production of raw-starch-degrading enzyme regulation in Penicillium oxalicum) was identified to regulate RSDE production in P. oxalicum; however, its regulatory mechanism remains unclear. Here we show that PoxRsrA1434-1730 was the transcriptional activation domain, with essential residues, D1508, W1509 and M1510. SANT (SWI3, ADA2, N-CoR and TFIIIB)-like domain 1 (SANT1) bound to DNA at the sequence 5'-RHCDDGGD-3' in the promoter regions of genes encoding major amylases, with an essential residue, R866. SANT2 interacted with a putative 3-hydroxyisobutyryl-CoA hydrolase, which suppressed phosphorylation at tyrosines Y1127 and Y1170 of PoxRsrA901-1360, thereby inhibiting RSDE biosynthesis. PoxRsrA1135-1439 regulated mycelial sporulation by interacting with Mediator subunit Med6, whereas PoxRsrA1440-1794 regulated RSDE biosynthesis by binding to Med31. Overexpression of PoxRsrA increased sporulation and RSDE production. These findings provide insights into the regulatory mechanisms of fungal RSDE biosynthesis.

MED19 encodes two unique protein isoforms that confer prostate cancer growth under low androgen through distinct gene expression programs.

MED19, a component of the mediator complex and a co-regulator of the androgen receptor (AR), is pivotal in prostate cancer cell proliferation. MED19 has two isoforms: a full-length "canonical" and a shorter "alternative" variant. Specific antibodies were developed to investigate these isoforms. Both exhibit similar expression in normal prostate development and adult prostate tissue, but the canonical isoform is elevated in prostate adenocarcinomas. Overexpression of canonical MED19 in LNCaP cells promotes growth under conditions of androgen deprivation in vitro and in vivo, mirroring earlier findings with alternative MED19-overexpressing LNCaP cells. Interestingly, alternative MED19 cells displayed strong colony formation in clonogenic assays under conditions of androgen deprivation, while canonical MED19 cells did not, suggesting distinct functional roles. These isoforms also modulated gene expression differently. Canonical MED19 triggered genes related to extracellular matrix remodeling while suppressing those involved in androgen-inactivating glucuronidation. In contrast, alternative MED19 elevated genes tied to cell movement and reduced those associated with cell adhesion and differentiation. The ratio of MED19 isoform expression in prostate cancers shifts with the disease stage. Early-stage cancers exhibit higher canonical MED19 expression than alternative MED19, consistent with canonical MED19's ability to promote cell proliferation under androgen deprivation. Conversely, alternative MED19 levels were higher in later-stage metastatic prostate cancer than in canonical MED19, reflecting alternative MED19's capability to enhance cell migration and autonomous cell growth. Our findings suggest that MED19 isoforms play unique roles in prostate cancer progression and highlights MED19 as a potential therapeutic target for both early and late-stage prostate cancer.

RISING STARS: Role of MED12 mutation in the pathogenesis of uterine fibroids.

Abstract: Uterine fibroids (UFs) are benign tumors arising from the uterus, characterized by accumulation of abundant extracellular matrix (ECM) and sex steroid-dependent growth. Women with symptomatic UFs have reduced quality of life and decreased labor productivity. Among the driver gene mutations identified in UFs, mutations in MED12, a component of the cyclin-dependent kinase (CDK) Mediator module, are the most common and observed in 50-80% of UFs. They are gain-of-function mutations and are more frequently observed in Black women and commonly observed even in small UFs. MED12 mutation-positive UFs (MED12-UFs) often develop multiple rather than solitary and have distinct gene expression profiles, DNA methylomes, transcriptomes, and proteomes. Gene expressions related to ECM organization and collagen-rich ECM components are upregulated, and impaired Mediator kinase activity and dysregulation of Wnt/ß-catenin signaling are identified in MED12-UFs. Clinically, the UF shrinking effect of gonadotropin-releasing hormone agonists and ulipristal acetate is dependent on the MED12 mutation status. Understanding of characteristics of MED12-UFs and functions of MED12 mutations for UF tumorigenesis may elucidate the pathophysiology of UFs, leading to the development of new therapeutic options in women with symptomatic UFs.

OsMED16, a tail subunit of Mediator complex, interacts with OsE2Fa to synergistically regulate rice leaf development and blast resistance.

Mediator, a universal eukaryotic coactivator, is a multiprotein complex to transduce information from the DNA-bound transcription factors to the RNA polymerase II transcriptional machinery. In this study, the biofunctions of a rice mediator subunit OsMED16 in leaf development and blast resistance were characterized. OsMED16 encodes a putative protein of 1170 amino acids, which is 393 bp shorted than the version in Rice Genome Annotation Project databases. Overexpression of OsMED16 plants exhibited wider leaves with larger and more numerous cells in lateral axis, and enhanced resistance to M. oryzae with hyperaccumulated salicylic acid. Further analysis revealed that OsMED16 interacts with OsE2Fa in nuclei, and the complex could directly regulate the transcriptional levels of several genes involved in cell cycle regulation and SA mediated blast resistance, such as OsCC52A1, OsCDKA1, OsCDKB2;2, OsICS1 and OsWRKY45. Altogether, this study proved that OsMED16 is a positive regulator of rice leaf development and blast resistance, and providing new insights into the crosstalk between cell cycle regulation and immunity.

CRISPR screen identifies CEBPB as contributor to dyskeratosis congenita fibroblast senescence via augmented inflammatory gene response.

Aging is the consequence of intra- and extracellular events that promote cellular senescence. Dyskeratosis congenita (DC) is an example of a premature aging disorder caused by underlying telomere/telomerase-related mutations. Cells from these patients offer an opportunity to study telomere-related aging and senescence. Our previous work has found that telomere shortening stimulates DNA damage responses (DDRs) and increases reactive oxygen species (ROS), thereby promoting entry into senescence. This work also found that telomere elongation via TERT expression, the catalytic component of the telomere-elongating enzyme telomerase, or p53 shRNA could decrease ROS by disrupting this telomere-DDR-ROS pathway. To further characterize this pathway, we performed a CRISPR/Cas9 knockout screen to identify genes that extend life span in DC cells. Of the cellular clones isolated due to increased life span, 34% had a guide RNA (gRNA) targeting CEBPB, while gRNAs targeting WSB1, MED28, and p73 were observed multiple times. CEBPB is a transcription factor associated with activation of proinflammatory response genes suggesting that inflammation may be present in DC cells. The inflammatory response was investigated using RNA sequencing to compare DC and control cells. Expression of inflammatory genes was found to be significantly elevated (P < 0.0001) in addition to a key subset of these inflammation-related genes [IL1B, IL6, IL8, IL12A, CXCL1 (GROa), CXCL2 (GROb), and CXCL5]. which are regulated by CEBPB. Exogenous TERT expression led to downregulation of RNA/protein CEBPB expression and the inflammatory response genes suggesting a telomere length-dependent mechanism to regulate CEBPB. Furthermore, unlike exogenous TERT and p53 shRNA, CEBPB shRNA did not significantly decrease ROS suggesting that CEBPB's contribution in DC cells' senescence is ROS independent. Our findings demonstrate a key role for CEBPB in engaging senescence by mobilizing an inflammatory response within DC cells.