Mitogen-activated Protein Kinase Gene Research Articles

Identification and analysis of MAPK cascade gene families of Camellia oleifera and their roles in response to cold stress.

Low-temperature severely limits the growth and development of Camellia oleifera (C. oleifera). The mitogen-activated protein kinase (MAPK) cascade plays a key role in the response to cold stress. Our study aims to identify MAPK cascade genes in C. oleifera and reveal their roles in response to cold stress. In our study, we systematically identified and analyzed the MAPK cascade gene families of C. oleifera, including their physical and chemical properties, conserved motifs, and multiple sequence alignments. In addition, we characterized the interacting networks of MAPKK kinase (MAPKKK)-MAPK kinase (MAPKK)-MAPK in C. oleifera. The molecular mechanism of cold stress resistance of MAPK cascade genes in wild C. oleifera was analyzed by differential gene expression and real-time quantitative reverse transcription-PCR (qRT-PCR). In this study, 21 MAPKs, 4 MAPKKs and 55 MAPKKKs genes were identified in the leaf transcriptome of C. oleifera. According to the phylogenetic results, MAPKs were divided into 4 groups (A, B, C and D), MAPKKs were divided into 3 groups (A, B and D), and MAPKKKs were divided into 2 groups (MEKK and Raf). Motif analysis showed that the motifs in each subfamily were conserved, and most of the motifs in the same subfamily were basically the same. The protein interaction network based on Arabidopsis thaliana (A. thaliana) homologs revealed that MAPK, MAPKK, and MAPKKK genes were widely involved in C. oleifera growth and development and in responses to biotic and abiotic stresses. Gene expression analysis revealed that the CoMAPKKK5/CoMAPKKK43/CoMAPKKK49-CoMAPKK4-CoMAPK8 module may play a key role in the cold stress resistance of wild C. oleifera at a high-elevation site in Lu Mountain (LSG). This study can facilitate the mining and utilization of genetic resources of C. oleifera with low-temperature tolerance.

FsCGBP, a Cutinase G-Box Binding Protein, Regulates the Growth, Development, and Virulence of Fusarium sacchari, the Pathogen of Sugarcane Pokkah Boeng Disease.

Fusarium sacchari is a causal agent of sugarcane Pokkah boeng, an important fungal disease that causes a considerable reduction in yield and sugar content in susceptible varieties of sugarcane worldwide. Despite its importance, the fungal factors that regulate the virulence of this pathogen remain largely unknown. In our previous study, mapping of an insertional mutant defect in virulence resulted in the identification of a cutinase G-box binding protein gene, designated FsCGBP, that encodes a C2H2-type transcription factor (TF). FsCGBP was shown to localize in the nuclei, and the transcript level of FsCGBP was significantly upregulated during the infection process or in response to abiotic stresses. Deletion or silencing of FsCGBP resulted in a reduction in mycelial growth, conidial production, and virulence and a delay in conidial germination in the F. sacchari. Cutinase genes FsCUT2, FsCUT3, and FsCUT4 and the mitogen-activated protein kinase (MAPK) genes FsHOG1, FsMGV1, and FsGPMK1, which were significantly downregulated in ΔFsCGBP. Except for FsHOG1, all of these genes were found to be transcriptionally activated by FsCGBP using the yeast one-hybrid system in vitro. The deletion of individual cutinase genes did not result in any of the phenotypes exhibited in the ΔFsCGBP mutant, except for cutinase activity. However, disruption of the MAPK pathway upon deletion of FsMGV1 or FsGPMK1 resulted in phenotypes similar to those of the ΔFsCGBP mutant. The above results suggest that FsCGBP functions by regulating the MAPK pathway and cutinase genes, providing new insights into the mechanism of virulence regulation in F. sacchari.

The basic leucine zipper transcription factor MeaB is critical for biofilm formation, cell wall integrity, and virulence in Aspergillus fumigatus.

The regulation of fungal cell wall biosynthesis is crucial for cell wall integrity maintenance and directly impacts fungal pathogen virulence. Although numerous genes are involved in fungal cell wall polysaccharide biosynthesis through multiple pathways, the underlying regulatory mechanism is still not fully understood. In this study, we identified and functionally characterized a direct downstream target of SomA, the basic-region leucine zipper transcription factor MeaB, playing a certain role in Aspergillus fumigatus cell wall integrity. Loss of meaB reduces hyphal growth, causes severe defects in galactosaminogalactan-mediated biofilm formation, and attenuates virulence in a Galleria mellonella infection model. Furthermore, the meaB null mutant strain exhibited hypersensitivity to cell wall-perturbing agents and significantly alters the cell wall structure. Transcriptional profile analysis revealed that MeaB positively regulates the expression of the galactosaminogalactan biosynthesis and β-1,3-glucanosyltransferase genes uge3, agd3, and sph3 and gel1, gel5, and gel7, respectively, as well as genes involved in amino sugar and nucleotide sugar metabolism. Further study demonstrated that MeaB could respond to cell wall stress and contribute to the proper expression of mitogen-activated protein kinase genes mpkA and mpkC in the presence of different concentrations of congo red. In conclusion, A. fumigatus MeaB plays a critical role in cell wall integrity by governing the expression of genes encoding cell wall-related proteins, thus impacting the virulence of this fungus.IMPORTANCEAspergillus fumigatus is a common opportunistic mold that causes life-threatening infections in immunosuppressed patients. The fungal cell wall is a complex and dynamic organelle essential for the development of pathogenic fungi. Genes involved in cell wall polysaccharide biosynthesis and remodeling are crucial for fungal pathogen virulence. However, the potential regulatory mechanism for cell wall integrity remains to be fully defined in A. fumigatus. In the present study, we identify basic-region leucine zipper transcription factor MeaB as an important regulator of cell wall galactosaminogalactan biosynthesis and β-1,3-glucan remodeling that consequently impacts stress response and virulence of fungal pathogens. Thus, we illuminate a mechanism of transcriptional control fungal cell wall polysaccharide biosynthesis and stress response. As these cell wall components are promising therapeutic targets for fungal infections, understanding the regulatory mechanism of such polysaccharides will provide new therapeutic opportunities.

Mechanism of IL-17 Signaling Pathway in Spleen Inflammatory Response Induced by Altitude Hypoxia in Mice

To explore the mechanism of spleen tissue inflammatory response induced by altitude hypoxia in mice. C57BL/6 mice were randomly assigned to a plain, i.e., low-altitude, normoxia group and an altitude hypoxia group, with 5 mice in each group. In the plain normoxia group, the mice were kept in a normoxic environment at the altitude of 400 m above sea level (with an oxygen concentration of 19.88%). The mice in the altitude hypoxia group were kept in an environment at the altitude of 4200 m above sea level (with an oxygen concentration of 14.23%) to establish the animal model of altitude hypoxia. On day 30, spleen tissues were collected to determine the splenic index. HE staining was performed to observe the histopathological changes in the spleen tissues of the mice. Real time fluorogenic quantitative PCR (RT-qPCR) and Western blot were conducted to determine the mRNA and protein expressions of interleukin (IL)-6, IL-12, and IL-1β in the spleen tissue of the mice. High-throughput transcriptome sequencing was performed with RNA sequencing (RNA-seq). KEGG enrichment analysis was performed for the differentially expressed genes (DEGs). The DEGs in the key pathways were verified by RT-qPCR. Compared with the plain normoxia group, the mice exposed to high-altitude hypoxic environment had decreased spleen index (P<0.05) and exhibited such pathological changes as decreased white pulp, enlarged germinal center, blurred edge, and venous congestion. The mRNA and protein expression levels of IL-6, IL-12, and IL-1β in the spleen tissue of mice in the altitude hypoxia group were up-regulated (P<0.05). According to the results of transcriptome sequencing and KEGG pathway enrichment analysis, 4218 DEGs were enriched in 178 enrichment pathways (P<0.05). DEGs were significantly enriched in multiple pathways associated with immunity and inflammation, such as T cell receptor signaling pathway, TNF signaling pathway, and IL-17 signaling pathway (P<0.05) in the spleen of mice exposed to high-altitude hypoxic environment. Among them, IL-17 signaling pathway and the downstream inflammatory factors were highly up-regulated (P<0.05). Compared with the plain normoxia group, the mRNA expression levels of key genes in the IL-17 signaling pathway, including IL-17, IL-17R, and mitogen-activated protein kinase genes (MAPKs), and the downstream inflammatory factors, including matrix metallopeptidase 9 (MMP9), S100 calcium binding protein A8 gene (S100A8), S100 calcium binding protein A9 gene (S100A9), and tumor necrosis factor α (TNF-α), were up-regulated or down-regulated (P<0.05) in the altitude hypoxia group. According to the validation of RT-qPCR results, the mRNA expression levels of DEGs were consistent with the RNA-seq results. Altitude hypoxia can induce inflammatory response in the mouse spleen tissue by activating IL-17 signaling pathway and promoting the release of downstream inflammatory factors.

OsMKK1 is a novel element that positively regulates the Xa21-mediated resistance response to Xanthomonas oryzae pv. oryzae in rice.

OsMKK1, a MAPK gene, positively regulates rice Xa21-mediated resistance response and also plays roles in normal growth and development process of rice. The mitogen-activated protein kinase (MAPK) cascade was highly conserved among eukaryotes, which played crucial roles in plant responses to pathogen infection. Bacterial blight is the most devastating bacterial disease. Xa21 confers broad-spectrum resistance to Xanthomonas oryzae pv. Oryzae (Xoo). This study identified that the transcription level of OsMKK1 was up-regulated in resistant response against Xoo, thus overexpression (OsMKK1-OX) and RNA interference (OsMKK1-RNAi) transgenic rice lines under the background of Xa21 was constructed. Compared with recipient control plants 4021, the OsMKK1-OX lines significantly enhanced disease resistance to Xoo, on the contrary, the resistance of OsMKK1-RNAi lines was weakened, demonstrated that OsMKK1 played a positive role in Xa21-mediated disease resistance pathway. A number of pathogenesis-related proteins, including PR1A, PR2 and PR10A showed enhanced expression in OsMKK1-OX lines, supported that these PR genes may be regulated by OsMKK1 to participate in the defense responses. In addition, the agronomic traits of OsMKK1 transgenic plants were affected. Overall, these results revealed the role of OsMKK1 in Xa21-mediated resistance against Xoo and in the normal growth and development process in rice.

Genome-Wide Identification, Evolution, and Expression Analysis of the MAPK Gene Family in Rosaceae Plants

Mitogen-activated protein kinases (MAPKs) are crucial regulators in coping with abiotic and biotic stresses, including drought, salinity, fungi, and pathogens. However, little is known about the characteristics, evolution process, and functional divergence of the MAPK gene family in Rosaceae plants. A total of 97 MAPK members were identified in six Rosaceae species, including 12 genes in Fragaria vesca, 22 genes in Malus domestica, 23 genes in Pyrus bretschneideri, 12 genes in Prunus mume, 14 genes in Prunus persica, and 14 genes in Rosa chinensis. All MAPK members of six Rosaceae plants were categorized into four clusters by the phylogenetic relationship analysis. Collinearity analysis discovered that both segmental duplication and tandem duplication contributed to the expansion of MAPK family genes in Rosaceae plants. And the analysis of motifs and gene structures indicated that the evolution of the MAPK gene family was highly conserved among phylogenetic clusters in Rosaceae species. In addition, the dN/dS rates of MAPK paralogous gene pairs were below one, suggesting the MAPK gene family in Rosaceae was driven by purifying selective pressure. Furthermore, functional divergence analysis discovered that 14 amino acid residues were detected as potentially key sites for functional divergence of MAPK family genes between different cluster pairs, specifically Type I functional divergence. The analysis of functional distance indicated that cluster C retained more of the original functional features, while cluster B exhibited functional specialization. Moreover, the expression profiles revealed that PmMAPK8, PmMAPK9, and PmMAPK10 were both highly expressed under drought stress and low temperature conditions. This study aims to comprehensively analyze the evolutionary process and functional analyses of the MAPK gene family in Rosaceae plants, which will lay the foundation for future studies into MAPK genes of Rosaceae in response to drought and cold stress.

Abstract B082: A novel, potent and selective ribonucleotide reductase (RNR) inhibitor, BBI-825, blocks extrachromosomal DNA (ecDNA) amplification-mediated resistance to KRASG12C inhibitor in colorectal cancer (CRC)

Abstract Introduction: KRASG12C inhibitors are a new therapeutic approach to treat KRAS mutant-driven cancers, but as with other oncogene directed therapies, adaptive resistance develops quickly and frequently. The predominant resistance mechanisms are 1) secondary mutations in KRAS and/or other mitogen-activated protein kinase (MAPK) signaling genes and 2) amplification of KRAS or MAPK genes. Extrachromosomal DNA (ecDNA) are the predominant site of focal high copy number oncogene or resistance gene amplifications in human cancers. Previous studies have demonstrated KRASG12C amplification on ecDNA to be an acquired resistance mechanism after treatment with approved KRASG12C inhibitors. Cancers enabled by ecDNA remain underserved by current therapeutic options, including targeted therapies, and have poor prognosis. An in silico “loss of function” screen revealed ribonucleotide reductase (RNR) as a critical target required for the survival of ecDNA amplified tumor cells. RNR is the rate-limiting enzyme in the biosynthesis of deoxyribonucleotide triphosphates (dNTP), the building blocks of DNA and ecDNA replication and repair. While non-selective drugs with RNR inhibitory activity (e.g., gemcitabine) indirectly validate RNR as a cancer target, no selective small molecules targeting RNR have been approved. Methods: We have developed BBI-825, a potent, selective, and orally bioavailable RNR inhibitor (RNRi) for the treatment of ecDNA-enabled oncogene or resistance gene amplified cancers. Results: BBI-825 inhibits RNR with an IC50 of 20 nM in vitro and reduces deoxyadenosine triphosphate (dATP) levels in ecDNA amplified cancer cells, with an EC50 of less than 100 nM. On target selectivity of BBI-825 was confirmed using SAFETYscan cellular screening assay investigating target selectivity over 78 targets spanning hormone receptors, kinases, calcium, GPCR, ion channel, and transporter signaling. Importantly, BBI-825 prevented resistance-conferring ecDNA-enabled amplification of KRASG12C in KRASG12C mutated colorectal cancer cells treated with the KRAS inhibitor adagrasib in vitro. Prevention of ecDNA amplification correlated with antiproliferation of BBI-825-treated tumor cells in long-term cultures. Treatment of KRASG12C mutated CRC tumor xenograft models with single agent adagrasib resulted in rapid acquired resistance through KRASG12C amplification on ecDNA. In concordance with in vitro observations, co-treatment with BBI-825 delayed the development of adagrasib resistance concurrent with an abrogation of ecDNA-enabled KRASG12C amplification (P=0.001). Furthermore, BBI-825 significantly inhibited the growth of pre-established adagrasib-resistant KRASG12C ecDNA-amplified tumors in vivo (tumor growth inhibition (TGI) = 92%, p&amp;lt;0.002), reinforcing clinical actionability in the KRAS inhibitor-refractory setting. Conclusions: These findings support the advancement of BBI-825 as a selective RNR inhibitor for the treatment of ecDNA-enabled oncogene or resistance gene amplified cancers, including KRASG12C mutant CRC. Citation Format: Sudhir Chowdhry, Ryan Hansen, Jacques Mauger, AnneMarie Pferdekamper, Edison Tse, Ben Norman, Jafar Moininazeri, Salvador Garcia, Yen Truong, Debbie Liao, Joshua Lange, Evan Holmes, Anthony Celeste, Dave Solis, Auzon Steffy, Joshua Plum, Julie Wiese, Julius Apuy, Ardalan Ardeshiri, Snezana Milutinovic, Deepti Wilkinson, Anthony Pinkerton, Christian Hassig, Shailaja Kasibhatla. A novel, potent and selective ribonucleotide reductase (RNR) inhibitor, BBI-825, blocks extrachromosomal DNA (ecDNA) amplification-mediated resistance to KRASG12C inhibitor in colorectal cancer (CRC) [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B082.

In Silico Analysis of the MAPK Gene Family in Cabbage and Its Expression during Development and Stress Response

Cabbage is often affected by an adverse environment and pathogens during its growth, resulting in a decline in yield and quality. Mitogen-activated protein kinases (MAPKs) play crucial roles in the development process, hormones, abiotic and biotic stresses, and cell division. So far, MAPKs have been characterized in various species. However, no systematic analysis of the MAPK family in cabbage has been performed. A total of 24 BoMAPK genes were identified and renamed according to Arabidopsis homologs; they were unevenly distributed on nine chromosomes. According to the conserved domain and phylogenetic relationship, BoMAPKs were divided into four subgroups, of which three belonged to subgroup A, four to subgroup B, three to subgroup C, and fourteen to subgroup D, respectively. There were 13 segmental duplication events in the cabbage genome. The Ka/Ks ratios for duplicated gene pairs of the MAPK family were less than 0.2, indicating that these BoMAPK genes have undergone purification selection in evolution. There were various cis-acting elements associated with stress, hormones, and development found in the promoter regions of most BoMAPK genes. Transcriptome data showed a high expression of BoMAPK3, BoMAPK4.1, and BoMAPK6.1 genes in various tissues. BoMAPK17.2, BoMAPK20.1 and BoMAPK20.2 were significantly induced by Plasmodiophora brassicae, as evidenced in the quantitative PCR (RT-qPCR) analysis, revealing their enormous potential to regulate stress response. RT-qPCR results showed how the transcriptional levels of BoMAPK genes varied substantially under abiotic stress at different time points. These analysis results provide a reference to further explore the function and evolution of BoMAPK genes in cabbage.

Selection and validation of internal control genes for quantitative real-time RT‒qPCR normalization of Phlebopus portentosus gene expression under different conditions.

Phlebopus portentosus (Berk. and Broome) Boedijn is an attractive edible mushroom and is considered the only bolete for which artificial cultivation in vitro has been achieved. Gene expression analysis has become widely used in research on edible fungi and is important for elucidating the functions of genes involved in complex biological processes. Selecting appropriate reference genes is crucial to ensuring reliable RT‒qPCR gene expression analysis results. In our study, a total of 12 candidate control genes were selected from 25 traditional housekeeping genes based on their expression stability in 9 transcriptomes of 3 developmental stages. These genes were further evaluated using geNorm, NormFinder, and RefFinder under different conditions and developmental stages. The results revealed that MSF1 domain-containing protein (MSF1), synaptobrevin (SYB), mitogen-activated protein kinase genes (MAPK), TATA-binding protein 1 (TBP1), and SPRY domain protein (SPRY) were the most stable reference genes in all sample treatments, while elongation factor 1-alpha (EF1), actin and ubiquitin-conjugating enzyme (UBCE) were the most unstably expressed. The gene SYB was selected based on the transcriptome results and was identified as a novel reference gene in P. portentosus. This is the first detailed study on the identification of reference genes in this fungus and may provide new insights into selecting genes and quantifying gene expression.

Gαs is dispensable for β-arrestin coupling but dictates GRK selectivity and is predominant for gene expression regulation by β2-adrenergic receptor

β-arrestins play a key role in G protein-coupled receptor (GPCR) internalization, trafficking, and signaling. Whether β-arrestins act independently of G protein-mediated signaling has not been fully elucidated. Studies using genome-editing approaches revealed that whereas G proteins are essential for mitogen-activated protein kinase activation by GPCRs., β-arrestins play a more prominent role in signal compartmentalization. However, in the absence of G proteins, GPCRs may not activate β-arrestins, thereby limiting the ability to distinguish G protein from β-arrestin-mediated signaling events. We used β2-adrenergic receptor (β2AR) and its β2AR-C tail mutant expressed in human embryonic kidney 293cells wildtype or CRISPR-Cas9 gene edited for Gαs, β-arrestin1/2, or GPCR kinases 2/3/5/6 in combination with arrestin conformational sensors to elucidate the interplay between Gαs and β-arrestins in controlling gene expression. We found that Gαs is not required for β2AR and β-arrestin conformational changes, β-arrestin recruitment, and receptor internalization, but that Gαs dictates the GPCR kinase isoforms involved in β-arrestin recruitment. By RNA-Seq analysis, we found that protein kinase A and mitogen-activated protein kinase gene signatures were activated by stimulation of β2AR in wildtype and β-arrestin1/2-KO cells but absent in Gαs-KO cells. These results were validated by re-expressing Gαs in the corresponding KO cells and silencing β-arrestins in wildtype cells. These findings were extended to cellular systems expressing endogenous levels of β2AR. Overall, our results support that Gs is essential for β2AR-promoted protein kinase A and mitogen-activated protein kinase gene expression signatures, whereas β-arrestins initiate signaling events modulating Gαs-driven nuclear transcriptional activity.

Schisandra extract ameliorates arthritis pathogenesis by suppressing the NF-κB and MAPK signalling pathways.

Schisandra chinensis is a medicinal plant used to treat various diseases. Extracts from the leaves or fruits of S. chinensis and their components are used in osteoarthritis (OA). The OA inhibitory effect of schisandrol A, one of its components, has been previously confirmed. We aimed to confirm the OA inhibitory effect of Schisandra (including components like schisandrol A) to identify why the inhibitory effect of the Schisandra extract is better. First, we investigated the effects of the Schisandra extract on OA as a potential therapeutic. Experimental OA was induced in a mouse model via destabilized medial meniscus surgery. The animals were orally administered the Schisandra extract; the inhibition of cartilage destruction was confirmed using histological analysis. In vitro analysis showed that the Schisandra extract attenuated osteoarthritic cartilage destruction by regulating IL-1β-induced MMP3 and COX-2 levels. The Schisandra extract inhibited IL-1β-induced degradation of IκB (NF-κB pathway) and IL-1β-induced phosphorylation of p38 and JNK (mitogen-activated protein kinase (MAPK) pathway). RNA-sequencing analysis showed that the Schisandra extract decreased the expression of IL-1β-induced MAPK and NF-κB signalling pathway-related genes more than schisandrol A alone. Therefore, Schisandra extract may be more effective than schisandrol A in preventing OA progression by regulating MAPK and NF-κB signalling.

Targeted Next-Generation Sequencing Improves the Prognostication of Patients with Disseminated Appendiceal Mucinous Neoplasms (Pseudomyxoma Peritonei).

Appendiceal mucinous neoplasms (AMNs) with disseminated disease (pseudomyxoma peritonei) are heterogeneous tumors with variable clinicopathologic behavior. Despite the development of prognostic systems, objective biomarkers are needed to stratify patients. With the advent of next-generation sequencing (NGS), it remains unclear if molecular testing can improve the evaluation of disseminated AMN patients. Targeted NGS was performed for 183 patients and correlated with clinicopathologic features to include American Joint Committee on Cancer/World Health Organization (AJCC/WHO) histologic grade, peritoneal cancer index (PCI), completeness of cytoreduction (CC) score, and overall survival (OS). Genomic alterations were identified for 179 (98%) disseminated AMNs. Excluding mitogen-activated protein kinase genes and GNAS due to their ubiquitous nature, collective genomic alterations in TP53, SMAD4, CDKN2A, and the mTOR genes were associated with older mean age, higher AJCC/WHO histologic grade, lymphovascular invasion, perineural invasion, regional lymph node metastasis, and lower mean PCI (p < 0.040). Patients harboring TP53, SMAD4, ATM, CDKN2A, and/or mTOR gene alterations were found to have lower OS rates of 55% at 5 years and 14% at 10 years, compared with 88% at 5 years and 88% at 10 years for patients without the aforementioned alterations (p < 0.001). Based on univariate and multivariate analyses, genomic alterations in TP53, SMAD4, ATM, CDKN2A, and/or the mTOR genes in disseminated AMNs were a negative prognostic factor for OS and independent of AJCC/WHO histologic grade, PCI, CC score, and hyperthermic intraperitoneal chemotherapy treatment (p = 0.006). Targeted NGS improves the prognostic assessment of patients with disseminated AMNs and identifies patients who may require increased surveillance and/or aggressive management.

MAPK family genes' influences on myogenesis in cattle: Genome-wide analysis and identification

The mitogen-activated protein kinase (MAPK) family is highly conserved in mammals, and is involved in a variety of physiological phenomena like regeneration, development, cell proliferation, and differentiation. In this study, 13 MAPK genes were identified in cattle and their corresponding protein properties were characterized using genome-wide identification and analysis. Phylogenetic analysis showed that the 13 BtMAPKs were cluster grouped into eight major evolutionary branches, which were segmented into three large subfamilies: ERK, p38 and JNK MAPK. BtMAPKs from the same subfamily had similar protein motif compositions, but considerably different exon-intron patterns. The heatmap analysis of transcriptome sequencing data showed that the expression of BtMAPKs was tissue-specific, with BtMAPK6 and BtMAPK12 highly expressed in muscle tissues. Furthermore, knockdown of BtMAPK6 and BtMAPK12 revealed that BtMAPK6 had no effect on myogenic cell proliferation, but negatively affected the differentiation of myogenic cells. In contrast, BtMAPK12 improved both the cell proliferation and differentiation. Taken together, these results provide novel insights into the functions of MAPK families in cattle, which could serve as a basis for further studies on the specific mechanisms of the genes in myogenesis.

Abstract 4258: Racial and ethnic differences in the mutational landscape of low-grade serous ovarian cancer

Abstract Objective To characterize the mutational landscape of low grade serous ovarian cancer (LGSOC) with racial/ethnic stratification. Methods The AACR Project GENIE database version 12.0 was queried via cBioPortal (http://genie.cbioportal.org) for low-grade serous ovarian cancer (LGSOC) samples. This is a publicly available, de-identified, multi-institutional database of next-generation sequencing genomic profiling results for tumor samples. Mutation frequencies for 9 homologous recombination deficiency (HRD) genes, 4 MAP-Kinase (MAP-K) pathway genes and 6 mismatch-repair (MMR) deficiency genes were reported and compared between racial/ethnic groups using chi-squared or Fischer’s exact tests. The threshold used for statistical significance was a two-sided alpha of 0.05. Results Among 317 tumor samples of LGSOC, there were high rates of MAP-K pathway gene mutations but low rates of HRD, MMR and TP53 gene mutations (Table 1). Non-Hispanic Black patients had significantly higher rates of KRAS mutations compared to non-Hispanic White patients (6/7, 86% vs 48/178, 27%, p&amp;lt;0.01). There was no difference in KRAS mutation frequency among Asian (6/17, 35%), Hispanic (7/24, 29%) and Native American (2/2, 100%) patients when compared to non-Hispanic White patients. BRAF mutations were less common compared to KRAS mutations (32/317, 10%), with no racial/ethnic differences in mutation frequency. Conclusion High rates of MAP-K pathway mutations in LGSOC support development and trials of drugs targeting this pathway, such as MEK protein inhibitors. Furthermore, prior literature has demonstrated the prognostic advantage of KRAS and BRAF mutations in LGSOC as well as the association of KRAS mutations with progression of serous borderline tumors to LGSOC. These racial/ethnic differences in frequencies of these mutations are thus hypothesis generating for clinical research to evaluate the impact of race/ethnicity on the development and prognosis of this rare ovarian cancer. Mutation frequencies of HR, MAP-kinase, MMR and TP53 genes in low-grade serous ovarian cancer Gene No. of samples with ≥1 mutation No. of samples profiled for mutation Mutation frequency BRCA1 3 287 1.05 BRCA2 7 287 2.44 BRIP1 5 271 1.85 CHEK2 2 278 0.72 BARD1 2 239 0.84 RAD51B - - - RAD51C - - - RAD51D 2 246 0.81 PALB2 2 279 0.72 KRAS 93 317 29.34 NRAS 29 317 9.15 BRAF 32 317 10.09 EIF1AX 14 144 9.72 MSH2 3 275 1.09 MSH3 1 113 0.88 MSH6 6 286 2.10 MLH1 1 317 0.32 MLH3 3 96 3.13 PMS2 1 270 0.37 TP53 12 317 3.79 Citation Format: Muhammad Danyal Ahsan, Emily M. Webster, Sarah R. Levi, Natalie T. Nguyen, Juan R. Cubillos-Ruiz, Evelyn Cantillo, Eloise Chapman-Davis, Melissa K. Frey, Kevin Holcomb. Racial and ethnic differences in the mutational landscape of low-grade serous ovarian cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4258.

Transcriptome Dynamics Underlying Planticine®-Induced Defense Responses of Tomato (Solanum lycopersicum L.) to Biotic Stresses

The induction of natural defense mechanisms in plants is considered to be one of the most important strategies used in integrated pest management (IPM). Plant immune inducers could reduce the use of chemicals for plant protection and their harmful impacts on the environment. Planticine® is a natural plant defense biostimulant based on oligomers of α(1→4)-linked D-galacturonic acids, which are biodegradable and nontoxic. The aim of this study was to define the molecular basis of Planticine's biological activity and the efficacy of its use as a natural plant resistance inducer in greenhouse conditions. Three independent experiments with foliar application of Planticine® were carried out. The first experiment in a climatic chamber (control environment, no pest pressure) subjected the leaves to RNA-seq analysis, and the second and third experiments in greenhouse conditions focused on efficacy after a pest infestation. The result was the RNA sequencing of six transcriptome libraries of tomatoes treated with Planticine® and untreated plants; a total of 3089 genes were found to be differentially expressed genes (DEGs); among them, 1760 and 1329 were up-regulated and down-regulated, respectively. DEG analysis indicated its involvement in such metabolic pathways and processes as plant-pathogen interaction, plant hormone signal transduction, MAPK signaling pathway, photosynthesis, and regulation of transcription. We detected up-regulated gene-encoded elicitor and effector recognition receptors (ELRR and ERR), mitogen-activated protein kinase (MAPKs) genes, and transcription factors (TFs), i.e., WRKY, ERF, MYB, NAC, bZIP, pathogenesis-related proteins (PRPs), and resistance-related metabolite (RRMs) genes. In the greenhouse trials, foliar application of Planticine® proved to be effective in reducing the infestation of tomato leaves by the biotrophic pathogen powdery mildew and in reducing feeding by thrips, which are insect herbivores. Prophylactic and intervention use of Planticine® at low infestation levels allows the activation of plant defense mechanisms.

Combination of the LARS1 Inhibitor, BC-LI-0186 with a MEK1/2 Inhibitor Enhances the Anti-Tumor Effect in Non-Small Cell Lung Cancer.

The mammalian target of rapamycin complex 1 (mTORC1) regulates cell growth and proliferation by growth factor coordination and amino acid availability. Leucyl-tRNA synthetase 1 (LARS1) senses the intracellular leucine concentration and mediates amino acid-induced activation of mTORC1. Thus, LARS1 inhibition could be useful in cancer treatment. However, the fact that mTORC1 can be stimulated by various growth factors and amino acids suggests that LARS1 inhibition alone has limitations in inhibiting cell growth and proliferation. We investigated the combined effects of BC-LI-0186, a LARS1 inhibitor, and trametinib, an MEK inhibitor, on non-small cell lung cancer (NSCLC). Protein expression and phosphorylation were observed by immunoblotting, and genes differentially expressed between BC-LI-0186-sensitive and -resistant cells were identified by RNA sequencing. The combined effect of the two drugs was inferred from the combination index values and a xenograft model. LARS1 expression was positively correlated with mTORC1 in NSCLC cell lines. BC-LI-0186 treatment of A549 and H460 cells maintained in media supplemented with fetal bovine serum revealed paradoxical phosphorylation of S6 and activation of mitogen- activated protein kinase (MAPK) signaling. Compared with BC-LI-0186-sensitive cells, -resistant cells showed enrichment of the MAPK gene set. The combination of trametinib and BC-LI-0186 inhibited the phosphorylation of S6, MEK, and extracellular signal-regulated kinase and their synergistic effects were confirmed in a mouse xenograft model. The combination of BC-LI-0186 and trametinib inhibited the non-canonical mTORC1-activating function of LARS1. Our study demonstrated a new therapeutic approach for NSCLC without targetable driver mutations.

Germline variation in RASAL2 may predict survival in patients with RAS-activated colorectal cancer.

Therapeutic agents that specifically target patients with RAS mutant colorectal cancer (CRC) are needed. We sought potential drug targets by relating genome-wide association study and survival data in patients with advanced CRC profiled for mitogen-activated protein kinase (MAPK) pathway mutations. In total, 694 patients from the clinical trials COIN and COIN-B had MAPK-activated CRCs (assigned as KRAS, NRAS, or BRAF mutant). Genome-wide single nucleotide polymorphism (SNP), gene, and gene-set analyses were performed to identify determinants of survival. For rs12028023 in RAS protein activator-like 2 (RASAL2), we studied its effect by MAPK pathway activation status (by comparing to 760 patients without MAPK-activated CRCs), MAPK gene mutation status, surface area of the primary tumor (as a marker of proliferation), and expression on RASAL2. In MAGMA genome-wide analyses, RASAL2 was the most significant gene associated with survival (p=2.0× 10-5 ). Patients carrying the minor (A) allele in the lead SNP, rs12028023 in intron 1 of RASAL2, had a median increase in survival of 167 days as compared with patients carrying the major allele. rs12028023 was predictive for survival by MAPK-activation status (pZ-test = 2.1× 10-3 ). Furthermore, rs12028023 improved survival in patients with RAS mutant (hazard ratio [HR]=0.62, 95% confidence intervals [CI]=0.5-0.8, p= 3.4× 10-5 ) but not BRAF mutant (p= 0.87) CRCs. The rs12028023 A-allele was associated with reduced surface area of the primary tumor (Beta=-0.037, standard error [SE]=0.017, p= 3.2× 10-2 ) and reduced RASAL2 expression in cultured fibroblasts (p= 1.6× 10-11 ). Our data demonstrate a prognostic role for RASAL2 in patients with MAPK-activated CRCs, with potential as a therapeutic target.

Harnessing the role of mitogen-activated protein kinases against abiotic stresses in plants.

Crop plants are vulnerable to various biotic and abiotic stresses, whereas plants tend to retain their physiological mechanisms by evolving cellular regulation. To mitigate the adverse effects of abiotic stresses, many defense mechanisms are induced in plants. One of these mechanisms is the mitogen-activated protein kinase (MAPK) cascade, a signaling pathway used in the transduction of extracellular stimuli into intercellular responses. This stress signaling pathway is activated by a series of responses involving MAPKKKs→MAPKKs→MAPKs, consisting of interacting proteins, and their functions depend on the collaboration and activation of one another by phosphorylation. These proteins are key regulators of MAPK in various crop plants under abiotic stress conditions and also related to hormonal responses. It is revealed that in response to stress signaling, MAPKs are characterized as multigenic families and elaborate the specific stimuli transformation as well as the antioxidant regulation system. This pathway is directed by the framework of proteins and stopping domains confer the related associates with unique structure and functions. Early studies of plant MAPKs focused on their functions in model plants. Based on the results of whole-genome sequencing, many MAPKs have been identified in plants, such as Arbodiposis, tomato, potato, alfalfa, poplar, rice, wheat, maize, and apple. In this review, we summarized the recent work on MAPK response to abiotic stress and the classification of MAPK cascade in crop plants. Moreover, we highlighted the modern research methodologies such as transcriptomics, proteomics, CRISPR/Cas technology, and epigenetic studies, which proposed, identified, and characterized the novel genes associated with MAPKs and their role in plants under abiotic stress conditions. In-silico-based identification of novel MAPK genes also facilitates future research on MAPK cascade identification and function in crop plants under various stress conditions.

Genome-wide identification of the mitogen-activated protein kinase kinases in pear and their functional analysis in response to black spot

The mitogen-activated protein kinase (MAPK) cascade is crucial to plant growth, development, and stress responses. MAPK kinases (MAPKK) play a vital role in linking upstream MAPKK kinases (MAPKKK) with the downstream MAPK. Black spot is one of the most serious fungal diseases of pear which is an important part of the fruit industry in China. The MAPKK genes have been identified in many plants, however, none has been reported in pear (Pyrus bretschneideri). In order to explore whether MAPK gene of pear is related to black spot disease, we designed this experiment. The present study investigated eight putative PbrMAPKK genes obtained from the Chinese white pear genome. The phylogenetic analysis revealed that PbrMAPKK genes were divided into A, B, C, and D groups. These PbrMAPKK genes are randomly distributed on 7 out of 17 chromosomes and mainly originated from the whole-genome duplication (WGD) event. The expression analysis of PbrMAPKK genes in seven pear tissues and the leaves of susceptible and resistant varieties after Alternaria alternata infection by quantitative real-time PCR (qRT-PCR) identified seven candidate genes associated with resistance. Furthermore, virus-induced gene silencing (VIGS) indicated that PbrMAPKK6 gene enhanced resistance to pear black spot disease in pear.

Comprehensive genome-wide identification and functional characterization of MAPK cascade gene families in Nelumbo

Mitogen-activated protein kinase (MAPK) cascade signaling pathway plays pivotal roles in various plant biological processes. However, systematic study of MAPK cascade gene families is yet to be conducted in lotus. Herein, 198 putative MAPK genes, including 152 MAP3Ks, 15 MKKs, and 31 MPKs genes were identified in Nelumbo. Segmental duplication was identified as the predominant factor driving MAPK cascade gene family expansion in lotus. MAPK cascade genes in N. nucifera and N. lutea shared high degree of sequence homologies, with 84, 9, and 19 homologous MAP3K, MKK, and MPK gene pairs being detected between the two species, respectively, with most genes predominantly undergoing purifying selection. Gene expression profiling indicated that NnMAPK cascade genes were extensively involved in plant development and submergence stress response. Co-expression analysis revealed potential interaction between transcription factors (TFs) and NnMAPK cascade genes in various biological processes. NnMKK showed predicted interactions with multiple NnMAP3K or NnMPK proteins, which suggested that functional diversity of MAPK cascade genes could be as a result of their complex protein interaction mechanisms. This first systematic analysis of MAPK cascade families in lotus provides deeper insights into their evolutionary dynamics and functional properties, which potentially could be crucial for lotus genetic improvement.