FAK loss reduces BRAFV600E-induced ERK phosphorylation to promote intestinal stemness and cecal tumor formation.

BRAFV600E mutation is a driver mutation in the serrated pathway to colorectal cancers. BRAFV600E drives tumorigenesis through constitutive downstream extracellular signal-regulated kinase (ERK) activation, but high-intensity ERK activation can also trigger tumor suppression. Whether and how oncogenic ERK signaling can be intrinsically adjusted to a 'just-right' level optimal for tumorigenesis remains undetermined. In this study, we found that FAK (Focal adhesion kinase) expression was reduced in BRAFV600E-mutant adenomas/polyps in mice and patients. In Vil1-Cre;BRAFLSL-V600E/+;Ptk2fl/fl mice, Fak deletion maximized BRAFV600E's oncogenic activity and increased cecal tumor incidence to 100%. Mechanistically, our results showed that Fak loss, without jeopardizing BRAFV600E-induced ERK pathway transcriptional output, reduced EGFR (epidermal growth factor receptor)-dependent ERK phosphorylation. Reduction in ERK phosphorylation increased the level of Lgr4, promoting intestinal stemness and cecal tumor formation. Our findings show that a 'just-right' ERK signaling optimal for BRAFV600E-induced cecal tumor formation can be achieved via Fak loss-mediated downregulation of ERK phosphorylation.

Research progress of acupuncture regulating ERK signaling pathway in the treatment of depression. / 针刺调控ERKä¿¡å·é€šè·¯æ²»ç–—æŠ‘éƒç—‡çš„ç ”ç©¶è¿›å±•.

Acupuncture treatment for depression has definite therapeutic efficacy, and its mechanism has been extensively studied. The extracellular regulatory protein kinase(ERK) signaling pathway is involved in the development and progression of depression. This article reviewed and summarized the research progress on the regulation of the ERK signaling pathway by acupuncture in the treatment of depression in recent years, focusing on the physiological activation and regulatory mechanism of the ERK signaling pathway, its association with the occurrence of depression, and the mechanisms through which acupuncture activates the ERK signaling pathway to treat depression (including enhancing neuronal synaptic plasticity, promoting the release of neurotrophic factors, and inhibiting neuronal apoptosis). Future research could explore the relationship between the ERK pathway and other pathways, investigate other brain regions besides the prefrontal cortex and hippocampus, examine differences in regulatory mechanisms between male and female patients, assess the effects of different acupuncture techniques on the ERK pathway, and increase efforts to explore mechanism of synaptic plasticity regulation, so as to provide reference for the clinical application and mechanism sludy of acupuncture in depression treatment.

Optimized new Shengmai powder inhibits myocardial fibrosis in heart failure by regulating the rat sarcoma/rapidly accelerated fibrosarcoma/mitogen-activated protein kinase kinase/extracellular regulated protein kinases signaling pathway.

OBJECTIVE: Exploring the effect of Optimized New Shengmai powder (, ONSMP) on myocardial fibrosis in heart failure (HF) based on rat sarcoma (RAS)/rapidly accelerated fibrosarcoma (RAF)/mitogen-activated protein kinase kinase (MEK)/extracellular regulated protein kinases (ERK) signaling pathway. METHODS: Randomized 70 Sprague-Dawley rats into sham (n = 10) and operation (n = 60) groups, then established the HF rat by ligating the left anterior descending branch of the coronary artery. We randomly divided the operation group rats into the model, ONSMP [including low (L), medium (M), and high (H) dose], and enalapril groups. After the 4-week drug intervention, echocardiography examines the cardiac function and calculates the ratios of the whole/left heart to the rat's body weight. Finally, we observed the degree of myocardial fibrosis by pathological sections, determined myocardium collagen (COL) I and COL Ⅲ content by enzyme-linked immunosorbent assay, detected the mRNA levels of COL I, COL Ⅲ, α-smooth muscle actin (α-SMA), and c-Fos proto-oncogene (c-Fos) by universal real-time, and detected the protein expression of p-RAS, p-RAF, p-MEK1/2, p-ERK1/2, p-ETS-like-1 transcription factor (p-ELK1), p-c-Fos, α-SMA, COL I, and COL Ⅲ by Western blot. RESULTS: ONSMP can effectively improve HF rat's cardiac function, decrease cardiac organ coefficient, COL volume fraction, and COL I/Ⅲ content, down-regulate the mRNA of COL I/Ⅲ, α-SMA and c-Fos, and the protein of p-RAS, p-RAF, p-MEK1/ 2, p-ERK1/2, p-ELK1, c-Fos, COL Ⅰ/Ⅲ, and α-SMA. CONCLUSIONS: ONSMP can effectively reduce myocardial fibrosis in HF rats, and the mechanism may be related to the inhibition of the RAS/RAF/MEK/ERK signaling pathway.

Oncogenic Kras induces spatiotemporally specific tissue deformation through converting pulsatile into sustained ERK activation.

Tissue regeneration and maintenance rely on coordinated stem cell behaviours. This orchestration can be impaired by oncogenic mutations leading to cancer. However, it is largely unclear how oncogenes perturb stem cells' orchestration to disrupt tissue. Here we used intravital imaging to investigate the mechanisms by which oncogenic Kras mutation causes tissue disruption in the hair follicle. Through longitudinally tracking hair follicles in live mice, we found that KrasG12D, a mutation that can lead to squamous cell carcinoma, induces epithelial tissue deformation in a spatiotemporally specific manner, linked with abnormal cell division and migration. Using a reporter mouse capture real-time ERK signal dynamics at the single-cell level, we discovered that KrasG12D, but not a closely related mutation HrasG12V, converts ERK signal in stem cells from pulsatile to sustained. Finally, we demonstrated that interrupting sustained ERK signal reverts KrasG12D-induced tissue deformation through modulating specific features of cell migration and division.

circUSP13 facilitates the fast-to-slow myofiber shift via the MAPK/ERK signaling pathway in goat skeletal muscles.

Understanding how skeletal muscle fiber proportions are regulated is essential for understanding muscle function and improving the quality of mutton. While circular RNA (circRNA) has a critical function in myofiber type transformation, the specific mechanisms are not yet fully understood. Prior evidence indicates that circular ubiquitin-specific peptidase 13 (circUSP13) can promote myoblast differentiation by acting as a ceRNA, but its potential role in myofiber switching is still unknown. Herein, we found that circUSP13 enhanced slow myosin heavy chain (MyHC-slow) and suppressed MyHC-fast expression in goat primary myoblasts (GPMs). Meanwhile, circUSP13 evidently enhanced the remodeling of the mitochondrial network while inhibiting the autophagy of GPMs. We obtained fast-dominated myofibers, via treatment with rotenone, and further demonstrated the positive role of circUSP13 in the fast-to-slow transition. Mechanistically, activation of the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway significantly impaired the slow-to-fast shift in fully differentiated myotubes, which was restored by circUSP13 or IGF1 overexpression. In conclusion, circUSP13 promoted the fast-to-slow myofiber type transition through MAPK/ERK signaling in goat skeletal muscle. These findings provide novel insights into the role of circUSP13 in myofiber type transition and contribute to a better understanding of the genetic mechanisms underlying meat quality.

FHND004 inhibits malignant proliferation of multiple myeloma by targeting PDZ-binding kinase in MAPK pathway.

Inhibitors of Epidermal growth factor receptor tyrosine kinase (EGFR-TKIs) are producing impressive benefits to responsive types of cancers but challenged with drug resistances. FHND drugs are newly modified small molecule inhibitors based on the third-generation EGFR-TKI AZD9291 (Osimertinib) that are mainly for targeting the mutant-selective EGFR, particularly for the non-small cell lung cancer (NSCLC). Successful applications of EGFR-TKIs to other cancers are less certain, thus the present pre-clinical study aims to explore the anticancer effect and downstream targets of FHND in multiple myeloma (MM), which is an incurable hematological malignancy and reported to be insensitive to first/second generation EGFR-TKIs (Gefitinib/Afatinib). Cell-based assays revealed that FHND004 and FHND008 significantly inhibited MM cell proliferation and promoted apoptosis. The RNA-seq identified the involvement of the MAPK signaling pathway. The protein chip screened PDZ-binding kinase (PBK) as a potential drug target. The interaction between PBK and FHND004 was verified by molecular docking and microscale thermophoresis (MST) assay with site mutation (N124/D125). Moreover, the public clinical datasets showed high expression of PBK was associated with poor clinical outcomes. PBK overexpression evidently promoted the proliferation of two MM cell lines, whereas the FHND004 treatment significantly inhibited survival of 5TMM3VT cell-derived model mice and growth of patient-derived xenograft (PDX) tumors. The mechanistic study showed that FHND004 downregulated PBK expression, thus mediating ERK1/2 phosphorylation in the MAPK pathway. Our study not only demonstrates PBK as a promising novel target of FHND004 to inhibit MM cell proliferation, but also expands the EGFR kinase-independent direction for developing anti-myeloma therapy.

MAPK15 controls cellular responses to oxidative stress by regulating NRF2 activity and expression of its downstream target genes.

Oxidation processes in mitochondria and different environmental insults contribute to unwarranted accumulation of reactive oxygen species (ROS). These, in turn, rapidly damage intracellular lipids, proteins, and DNA, ultimately causing aging and several human diseases. Cells have developed different and very effective systems to control ROS levels. Among these, removal of excessive amounts is guaranteed by upregulated expression of various antioxidant enzymes, through activation of the NF-E2-Related Factor 2 (NRF2) protein. Here, we show that Mitogen Activated Protein Kinase 15 (MAPK15) controls the transactivating potential of NRF2 and, in turn, the expression of its downstream target genes. Specifically, upon oxidative stress, MAPK15 is necessary to increase NRF2 expression and nuclear translocation, by inducing its activating phosphorylation, ultimately supporting transactivation of cytoprotective antioxidant genes. Lungs are continuously exposed to oxidative damages induced by environmental insults such as air pollutants and cigarette smoke. Interestingly, we demonstrate that MAPK15 is very effective in supporting NRF2-dependent antioxidant transcriptional response to cigarette smoke of epithelial lung cells. Oxidative damage induced by cigarette smoke indeed represents a leading cause of disability and death worldwide by contributing to the pathogenesis of different chronic respiratory diseases and lung cancer. Therefore, the development of novel therapeutic strategies able to modulate cellular responses to oxidative stress would be highly beneficial. Our data contribute to the necessary understanding of the molecular mechanisms behind such responses and identify new potentially actionable targets.

ERK-mediated curvature feedback regulates branching morphogenesis in lung epithelial tissue.

Intricate branching patterns emerge in internal organs due to the recurrent occurrence of simple deformations in epithelial tissues. During murine lung development, epithelial cells in distal tips of the single tube require fibroblast growth factor (FGF) signals emanating from their surrounding mesenchyme to form repetitive tip bifurcations. However, it remains unknown how the cells employ FGF signaling to convert their behaviors to achieve the recursive branching processes. Here, we show a mechano-chemical regulatory system underlying lung branching morphogenesis, orchestrated by extracellular signal-regulated kinase (ERK) as a downstream driver of FGF signaling. We found that tissue-scale curvature regulated ERK activity in the lung epithelium using two-photon live cell imaging and mechanical perturbations. ERK activation occurs specifically in epithelial tissues exhibiting positive curvature, regardless of whether the change in curvature was attributable to morphogenesis or perturbations. Moreover, ERK activation accelerates actin polymerization preferentially at the apical side of cells, mechanically contributing to the extension of the apical membrane, culminating in a reduction of epithelial tissue curvature. These results indicate the existence of a negative feedback loop between tissue curvature and ERK activity that transcends spatial scales. Our mathematical model confirms that this regulatory mechanism is sufficient to generate the recursive branching processes. Taken together, we propose that ERK orchestrates a curvature feedback loop pivotal to the self-organized patterning of tissues.

Braf V600E mutation in melanoma: translational current scenario

Melanoma was one of the translational cancer examples in clinic, including target therapy related to specific biomarkers impacting in the outcome of melanoma patients. Melanomagenesis involved a wide variety of mutations during his evolution; many of these mutated proteins have a kinase activity. One of the most cited proteins in melanoma is BRAF (about 50-60 % of melanomas harbors activating BRAF mutations), for these the most common is a substitution of valine to glutamic acid at codon 600 (p.V600E). Therefore, the precise identification of this underlying somatic mutation is essential; knowing the translational implications has opened a wide view of melanoma biology and therapy (AU)

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Tegumentary manifestations of Noonan and Noonan-related syndromes

OBJECTIVES: Noonan and Noonan-related syndromes are common autosomal dominant disorders with neuro-cardio-facial-cutaneous and developmental involvement. The objective of this article is to describe the most relevant tegumentary findings in a cohort of 41 patients with Noonan or Noonan-related syndromes and to detail certain aspects of the molecular mechanisms underlying ectodermal involvement. METHODS: A standard questionnaire was administered. A focused physical examination and a systematic review of clinical records was performed on all patients to verify the presence of tegumentary alterations. The molecular analysis of this cohort included sequencing of the following genes in all patients: PTPN1, SOS1, RAF1, KRAS, SHOC2 and BRAF. RESULTS: The most frequent tegumentary alterations were xeroderma (46%), photosensitivity (29%), excessive hair loss (24%), recurrent oral ulcers (22%), curly hair (20%), nevi (17%), markedly increased palmar and plantar creases (12%), follicular hyperkeratosis (12%), palmoplantar hyperkeratosis (10%), café-au-lait spots (10%) and sparse eyebrows (7%). Patients with mutations in PTPN11 had lower frequencies of palmar and plantar creases and palmar/plantar hyperkeratosis compared with the other patients. CONCLUSIONS: We observed that patients with mutations in genes directly involved in cell proliferation kinase cascades (SOS1, BRAF, KRAS and RAF1) had a higher frequency of hyperkeratotic lesions compared with patients with mutations in genes that have a more complex interaction with and modulation of cell proliferation kinase cascades (PTPN11). .

Regulation of expression of matrix metalloproteinase-9 by JNK in Raw 264.7 cells: presence of inhibitory factor(s) suppressing MMP-9 induction in serum and conditioned media

Matrix metalloproteinase-9 (MMP-9) secreted from macrophages plays an important role in tissue destruction and inflammation through degradation of matrix proteins and proteolytic activation of cytokines/chemokines. Whereas the MEK-ERK and PI3K-Akt pathways up-regulate MMP-9 expression, regulation of MMP-9 by JNK remains controversial. Presently, we aimed to determine the role of JNK in MMP-9 regulation in Raw 264.7 cells. Inhibition of JNK by the JNK inhibitor SP600125 induced MMP-9 in the absence of serum and suppressed the expression of TNF-alpha, IL-6 and cyclooxygenase-2 in LPS-treated Raw 264.7 cells. In a knockdown experiment with small interfering RNA, suppression of JNK1 induced MMP-9 expression. Interestingly, mouse serum suppressed SP600125-mediated MMP-9 induction, similar to IFN-gamma. However, the inhibitory activity of mouse serum was not affected by pyridone 6, which inhibits Janus kinase downstream to IFN-gamma. In addition to mouse serum, conditioned media of Raw 264.7 cells contained the inhibitory factor(s) larger than 10 kDa, which suppressed SP600125- or LPS-induced MMP-9 expression. Taken together, these data suggest that JNK1 suppresses MMP-9 expression in the absence of serum. In addition, the inhibitory factor(s) present in serum or secreted from macrophages may negatively control MMP-9 expression.

The translation inhibitor anisomycin induces Elk-1-mediated transcriptional activation of egr-1 through multiple mitogen-activated protein kinase pathways

The early growth response-1 gene (egr-1) encodes a zinc-finger transcription factor Egr-1 and is rapidly inducible by a variety of extracellular stimuli. Anisomycin (ANX), a protein synthesis inhibitor, stimulates mitogen-activated protein kinase (MAPK) pathways and thereby causes a rapid induction of immediate-early response genes. We found that anisomycin treatment of U87MG glioma cells resulted in a marked, time-dependent increase in levels of Egr-1 protein. The results of Northern blot analysis and reporter gene assay of egr-1 gene promoter (Pegr-1) activity indicate that the ANX- induced increase in Egr-1 occurs at the transcriptional level. Deletion of the serum response element (SRE) in the 5'-flanking region of egr-1 gene abolished ANX-induced Pegr-1 activity. ANX induced the phosphorylation of the ERK1/2, JNK, and p38 MAPKs in a time-dependent manner and also induced transactivation of Gal4-Elk-1, suggesting that Elk-1 is involved in SRE-mediated egr-1 transcription. Transient transfection of dominant-negative constructs of MAPK pathways blocked ANX-induced Pegr-1 activity. Furthermore, pretreatment with specific MAPK pathway inhibitors, including the MEK inhibitor U0126, the JNK inhibitor SP600125, and the p38 kinase inhibitor SB202190, completely inhibited ANX-inducible expression of Egr-1. Taken together, these results suggest that all three MAPK pathways play a crucial role in ANX-induced transcriptional activation of Pegr-1 through SRE-mediated transactivation of Elk