Growth hormone stimulates phosphorylation and activation of elk-1 and expression of c-fos, egr-1, and junB through activation of extracellular signal-regulated kinases 1 and 2

Aberrant Expression and Oncogenic Activity of SPP1 in Hodgkin Lymphoma

Background: Hodgkin lymphoma (HL) is a B-cell-derived malignancy and one of the most frequent types of lymphoma. The tumour cells typically exhibit multiple genomic alterations together with aberrantly activated signalling pathways, driven by paracrine and/or autocrine modes. SPP1 (alias osteopontin) is a cytokine acting as a signalling activator and has been connected with relapse in HL patients. To understand its pathogenic role, here, we investigated the mechanisms and function of deregulated SPP1 in HL. Methods: We screened public patient datasets and cell lines for aberrant SPP1 expression. HL cell lines were stimulated with SPP1 and subjected to siRNA-mediated knockdown. Gene and protein activities were analyzed by RQ-PCR, ELISA, Western blot, and immuno-cytology. Results: SPP1 expression was detected in 8.3% of classic HL patients and in HL cell line SUP-HD1, chosen to serve as an experimental model. The gene encoding SPP1 is located at chromosomal position 4q22 and is genomically amplified in SUP-HD1. Transcription factor binding site analysis revealed TALE and HOX factors as potential regulators. Consistent with this finding, we showed that aberrantly expressed PBX1 and HOXB9 mediate the transcriptional activation of SPP1. RNA-seq data and knockdown experiments indicated that SPP1 signals via integrin ITGB1 in SUP-HD1. Accordingly, SPP1 activated NFkB in addition to MAPK/ERK which in turn mediated the nuclear import of ETS2, activating oncogenic JUNB expression. Conclusions: SPP1 is aberrantly activated in HL cell line SUP-HD1 via genomic copy number gain and by homeodomain transcription factors PBX1 and HOXB9. SPP1-activated NFkB and MAPK merit further investigation as potential therapeutic targets in affected HL patients.

The intersection of endocrine signaling and neuroimmune communication regulates muscle inflammation-induced nociception in neonatal mice

Neonatal pain is a significant clinical issue but the mechanisms by which pain is produced early in life are poorly understood. Our recent work has linked the transcription factor serum response factor downstream of local growth hormone (GH) signaling to incision-related hypersensitivity in neonates. However, it remains unclear if similar mechanisms contribute to inflammatory pain in neonates. We found that local GH treatment inhibited neonatal inflammatory myalgia but appeared to do so through a unique signal transducer and activator of transcription (STAT) dependent pathway within sensory neurons. The STAT1 transcription factor appeared to regulate peripheral inflammation itself by modulation of monocyte chemoattractant protein 1/C-C motif chemokine ligand 2 (MCP1/CCL2) release from sensory neurons. Data suggests that STAT1 upregulation, downstream of GH signaling, contributes to neonatal nociception during muscle inflammation through a novel neuroimmune loop involving chemokine release from primary afferents. Results could uncover new ways to treat muscle pain and inflammation in neonates.

GADD45β-MTK1 signaling axis mediates oncogenic stress-induced activation of the p38 and JNK pathways

The ERK pathway governs essential biological processes such as cell proliferation and survival, and its hyperactivation by various oncogenes ultimately drives carcinogenesis. However, normal mammalian cells typically recognize aberrant ERK signaling as oncogenic stress and respond by inducing cell cycle arrest or apoptosis through activation of the p38 and JNK pathways. Despite the critical role of this response in preventing carcinogenesis, the precise molecular mechanisms underlying oncogene-induced, ERK-dependent activation of p38/JNK and its tumor-suppressive effects remain unclear. Here, we demonstrate that MAP three kinase 1 (MTK1), a stress-responsive MAPKKK, serves as a key mediator of p38/JNK activation induced by oncogenic ERK signaling. Mechanistically, aberrant ERK signaling induces sustained expression of the transcription factor early growth response protein 1 (EGR1), which promotes the production of the MTK1 activator GADD45β, leading to persistent activation of MTK1-p38/JNK signaling. Gene knockout and transcriptome analyses revealed that this GADD45β/MTK1-mediated cross-talk between the ERK and p38/JNK pathways preferentially upregulates a specific set of genes involved in apoptosis and the immune response. Notably, the expression of EGR1, GADD45β, and MTK1 is frequently downregulated in many cancers with high ERK activity, resulting in the disruption of the tumor-suppressive ERK-p38/JNK cross-talk. Restoring GADD45β expression in cancer cells reactivates p38/JNK signaling and suppresses tumorigenesis. Our findings delineate a molecular mechanism by which normal cells sense and respond to oncogenic stress to prevent abnormal growth, and highlight the significance of its dysregulation in cancer.

Novel FGF21 analogues through structure-based optimization for therapeutic development

Fibroblast growth factor 21 (FGF21) plays a pivotal role in regulating metabolic processes and energy homeostasis, making it a promising therapeutic avenue for various obesity-related conditions. However, its therapeutic efficacy faces challenges due to its suboptimal pharmacokinetics and bioactivity. To overcome these limitations, we adapt a strategy in which key amino acid residues responsible for enhanced activity are pinpointed through sequence alignment and comparative analysis to develop long-acting FGF21 analogs. The mutant FGF21 analogs are fused with the Fc fragment. Here, we report the design, identification, and characterization of two distinct Fc-fused FGF21 analogs, Fc-FGF21(P119R) and Fc-FGF21(H125R), with significantly augmented potency. These findings hold promise for clinical applications, offering potential interventions for obesity-related metabolic disorders.

The Zebrafish Cerebellar Neural Circuits Are Involved in Orienting Behavior

Deficits in social behavior are found in neurodevelopmental disorders, including autism spectrum disorders (ASDs). Since abnormalities in cerebellar morphology and function are observed in ASD patients, the cerebellum is thought to play a role in social behavior. However, it remains unknown whether the cerebellum is involved in social behavior in other animals and how cerebellar circuits control social behavior. To address this issue, we employed zebrafish stereotyped orienting behavior as a model of social behaviors, in which a pair of adult zebrafish in two separate tanks approach each other, with one swimming at synchronized angles (orienting angles) with the other. We harnessed transgenic zebrafish that express botulinum toxin, which inhibits the release of neurotransmitters, in either granule cells or Purkinje cells (PCs), and zebrafish mutants of reelin, which is involved in the positioning of cerebellar neurons, including PCs. These zebrafish, deficient in the function or formation of cerebellar neural circuits, showed a significantly shorter period of orienting behavior compared with their control siblings. We found an increase in c-fos and egr1 expression in the cerebellum after the orienting behavior. These results suggest that zebrafish cerebellar circuits play an important role in social orienting behavior.

The intersection of endocrine signaling and neuroimmune communication regulates neonatal nociception

Neonatal pain is a significant clinical issue but the mechanisms by which pain is produced early in life are poorly understood. Our recent work has linked the transcription factor serum response factor downstream of local growth hormone (GH) signaling to incision-related hypersensitivity in neonates. However, it remains unclear if similar mechanisms contribute to inflammatory pain in neonates. We found that local GH treatment inhibited neonatal inflammatory myalgia but appeared to do so through a unique signal transducer and activator of transcription (STAT) dependent pathway within sensory neurons. The STAT1 transcription factor appeared to regulate peripheral inflammation itself by modulation of monocyte chemoattractant protein 1 (MCP1) release from sensory neurons. Data suggests that STAT1 upregulation, downstream of GH signaling, contributes to neonatal nociception during muscle inflammation through a novel neuroimmune loop involving cytokine release from primary afferents. Results could uncover new ways to treat muscle pain and inflammation in neonates.

MicroRNA-focused CRISPR/Cas9 screen identifies miR-142 as a key regulator of Epstein-Barr virus reactivation

Reactivation from latency plays a significant role in maintaining persistent lifelong Epstein-Barr virus (EBV) infection. Mechanisms governing successful activation and progression of the EBV lytic phase are not fully understood. EBV expresses multiple viral microRNAs (miRNAs) and manipulates several cellular miRNAs to support viral infection. To gain insight into the host miRNAs regulating transitions from EBV latency into the lytic stage, we conducted a CRISPR/Cas9-based screen in EBV+ Burkitt lymphoma (BL) cells using anti-Ig antibodies to crosslink the B cell receptor (BCR) and induce reactivation. Using a gRNA library against >1500 annotated human miRNAs, we identified miR-142 as a key regulator of EBV reactivation. Genetic ablation of miR-142 enhanced levels of immediate early and early lytic gene products in infected BL cells. Ago2-PAR-CLIP experiments with reactivated cells revealed miR-142 targets related to Erk/MAPK signaling, including components directly downstream of the B cell receptor (BCR). Consistent with these findings, disruption of miR-142 enhanced SOS1 levels and Mek phosphorylation in response to surface Ig cross-linking. Effects could be rescued by inhibitors of Mek (cobimetinib) or Raf (dabrafenib). Taken together, these results show that miR-142 functionally regulates SOS1/Ras/Raf/Mek/Erk signaling initiated through the BCR and consequently, restricts EBV entry into the lytic cycle.

Growth control of the kidney

The functional mass of kidney tissue in an adult is an important determinant of human health. Kidney formation during development is an essential determinant of the final nephron endowment of the adult organ, and no evidence has been reported that mice or humans are able to generate new nephrons after the developmental period. Mechanisms controlling organ growth after development are essential to establish the final adult organ size. The potential for organ growth is maintained in adult life and the size of one kidney may be significantly increased by loss of the contralateral kidney. The mouse has provided a model system for investigators to critically explore genetic, cell biological, and hormonal control of developmental and juvenile kidney growth. This article reviews three basic aspects of kidney size regulation: (1) Mechanisms that control nephron formation and how these are altered by the cessation of nephrogenesis at the end of the developmental period. (2) Applicability of the general model for growth hormone-insulin like growth factor control to kidney growth both pre- and postnatally. (3) Commonalities between mechanisms of juvenile kidney growth and the compensatory growth that is stimulated in adult life by reduction of kidney mass. Understanding the mechanisms that determine set-points for cell numbers and size in the kidney may inform ongoing efforts to generate kidney tissue from stem cells.

Hypothalamus-pituitary axis transcriptomic modification dependent on growth rate in geese (Anser anser domesticus)

The hypothalamus-pituitary axis is involved in digest processing, stress response, energy storage and many other processes. In birds, this control differs from in mammals, such as regulation of appetite and satiety centre. The transcriptomics analyses of both brain structures can explain and identify the molecular processes related to body growth and development and nutritional status. Many reports describe chicken transcriptome in literature, but gene expression studies in the other poultry species are extremely rare. Therefore, the present research undertook the attempt to explain hypothalamus-pituitary processes in domestic geese-Polish White Kołuda®, main Polish line. After 16 weeks of fattening, significant differences in geese weight were observed. Therefore, transcriptome of pituitary and hypothalamus profiles could be compared between low and high growth rate geese groups. Due to the lack of domestic geese genome assembly in the public databases, we used three mapping approaches: de novo analysis, mapping to two other pink-footed and swan geese genomes. The functional examination showed that the most enriched biological process in the geese hypothalamus covered the immune response. Moreover, in the hypothalamus, proteins typical for the pituitary such as PRL and GH were differentially expressed (DE). Our study recommends one gene as a candidate for growth rate in geese-the FOS gene, which encodes Fos proto-oncogene-DE in both analysed tissues. The FOS gene is involved in regulating feeding behaviour, immune regulation, stimulating cellular proliferation and controlling growth hormone synthesis. Moreover, the present investigation indicates DE genes involved in gene expression regulation. The study delivers new information about the changes in the pituitary-hypothalamic axis in geese dependent on growth rate differences.

Identification of X-chromosomal genes that drive sex differences in embryonic stem cells through a hierarchical CRISPR screening approach

BACKGROUND

X-chromosomal genes contribute to sex differences, in particular during early development, when both X chromosomes are active in females. Double X-dosage shifts female pluripotent cells towards the naive stem cell state by increasing pluripotency factor expression, inhibiting the differentiation-promoting MAP kinase (MAPK) signaling pathway, and delaying differentiation.

RESULTS

To identify the genetic basis of these sex differences, we use a two-step CRISPR screening approach to comprehensively identify X-linked genes that cause the female pluripotency phenotype in murine embryonic stem cells. A primary chromosome-wide CRISPR knockout screen and three secondary screens assaying for different aspects of the female pluripotency phenotype allow us to uncover multiple genes that act in concert and to disentangle their relative roles. Among them, we identify Dusp9 and Klhl13 as two central players. While Dusp9 mainly affects MAPK pathway intermediates, Klhl13 promotes pluripotency factor expression and delays differentiation, with both factors jointly repressing MAPK target gene expression.

CONCLUSIONS

Here, we elucidate the mechanisms that drive sex-induced differences in pluripotent cells and our approach serves as a blueprint to discover the genetic basis of the phenotypic consequences of other chromosomal effects.

Manipulation of IRE1-Dependent MAPK Signaling by a Vibrio Agonist-Antagonist Effector Pair

Diverse bacterial pathogens employ effector delivery systems to disrupt vital cellular processes in the host (N. M. Alto and K. Orth, Cold Spring Harbor Perspect Biol 4:a006114, 2012, https://doi.org/10.1101/cshperspect.a006114). The type III secretion system 1 of the marine pathogen Vibrio parahaemolyticus utilizes the sequential action of four effectors to induce a rapid, proinflammatory cell death uniquely characterized by a prosurvival host transcriptional response (D. L. Burdette, M. L. Yarbrough, A Orvedahl, C. J. Gilpin, and K. Orth, Proc Natl Acad Sci USA 105:12497-12502, 2008, https://doi.org/10.1073/pnas.0802773105; N. J. De Nisco, M. Kanchwala, P. Li, J. Fernandez, C. Xing, and K. Orth, Sci Signal 10:eaa14501, 2017, https://doi.org/10.1126/scisignal.aal4501). Herein, we show that this prosurvival response is caused by the action of the channel-forming effector VopQ that targets the host V-ATPase, resulting in lysosomal deacidification and inhibition of lysosome-autophagosome fusion. Recent structural studies have shown how VopQ interacts with the V-ATPase and, while in the ER, a V-ATPase assembly intermediate can interact with VopQ, causing a disruption in membrane integrity. Additionally, we observed that VopQ-mediated disruption of the V-ATPase activates the IRE1 branch of the unfolded protein response (UPR), resulting in an IRE1-dependent activation of ERK1/2 MAPK signaling. We also find that this early VopQ-dependent induction of ERK1/2 phosphorylation is terminated by the VopS-mediated inhibitory AMPylation of Rho GTPase signaling. Since VopS dampens VopQ-induced IRE1-dependent ERK1/2 activation, we propose that IRE1 activates ERK1/2 phosphorylation at or above the level of Rho GTPases. This study illustrates how temporally induced effectors can work as in tandem as agonist/antagonist to manipulate host signaling and reveals new connections between V-ATPase function, UPR, and MAPK signaling.IMPORTANCE Vibrio parahaemolyticus is a seafood-borne pathogen that encodes two type 3 secretion systems (T3SS). The first system, T3SS1, is thought to be maintained in all strains of V. parahaemolyticus to maintain survival in the environment, whereas the second system, T3SS2, is linked to clinical isolates and disease in humans. Here, we found that first system targets evolutionarily conserved signaling systems to manipulate host cells, eventually causing a rapid, orchestrated cells death within 3 h. We have found that the T3SS1 injects virulence factors that temporally manipulate host signaling. Within the first hour of infection, the effector VopQ acts first by activating host survival signals while diminishing the host cell apoptotic machinery. Less than an hour later, another effector, VopS, reverses activation and inhibition of these signaling systems, ultimately leading to death of the host cell. This work provides example of how pathogens have evolved to manipulate the interplay between T3SS effectors to regulate host signaling pathways.

Classical and novel GH receptor signaling pathways

In this review, I summarize historical and recent features of the classical pathways activated by growth hormone (GH) through the cell surface GH receptor (GHR). GHR is a cytokine receptor superfamily member that signals by activating the non-receptor tyrosine kinase, JAK2, and members of the Src family kinases. Activation of the GHR engages STATs, PI3K, and ERK pathways, among others, and details of these now-classical pathways are presented. Modulating elements, including the SOCS proteins, phosphatases, and regulated GHR metalloproteolysis, are discussed. In addition, a novel physical and functional interaction of GHR with IGF-1R is summarized and discussed in terms of its mechanisms, consequences, and physiological and therapeutic implications.

miR-597-5p inhibits cell growth and promotes cell apoptosis by targeting ELK1 in pancreatic cancer

Pancreatic cancer is a malignant disease with poor prognosis. Emerging evidences have showed that miR-597-5p is closely related to tumor development. However, the functional roles of miR-597-5p in pancreatic cancer remain unknown. This study aimed to investigate the expression of miR-597-5p in pancreatic cancer tissues and cells, and explored its regulatory mechanism during pancreatic cancer progression. Pancreatic cancer and adjacent tissues were obtained to detect the expression of miR-597-5p by RT-qPCR. Cell growth, apoptosis, and related protein expression were, respectively, tested by CCK-8 assay, cell formation, wound healing, Transwell assay, flow cytometry, and western blotting. Finally, the pancreatic cancer mice model was constructed. In vitro and in vivo results showed that miR-597-5p expression was down-regulated in pancreatic cancer tissues and cell lines, and increased the overall survival of pancreatic cancer patients. Moreover, miR-597-5p decreased pancreatic cancer cell viability, reduced relative wound width, suppressed colony formation and decreased invasive cell number, as well as reduced the expression of proliferating cell nuclear antigen (PCNA), Ki67, Cyclin D1, N-cad, and Bcl-2. Meanwhile, it increased pancreatic cancer cell apoptosis and the expression of E-cad, cleaved caspase 3, and Bax. The dual-luciferase reporter assay confirmed miR-597-5p could directly target e-twenty six like-1 (ELK1) oncogene. The reduction of cell growth and the induction of cell apoptosis induced by miR-597-5p were reversed by ELK1. In addition, miR-597-5p inhibited the growth of pancreatic cancer in vivo. This study demonstrated that miR-597-5p may be a novel suppressor of pancreatic cancer. It inhibits pancreatic cancer cell growth and promotes apoptosis by the down-regulation of ELK1 in vitro and in vivo.

Characterization of a membrane-associated estrogen receptor in breast cancer cells and its contribution to hormone therapy resistance using a novel selective ligand

The estrogen receptor (ER) plays a role in the progression of hormone-dependent breast cancer and is a hormone therapy target. Estrogen acts as a transcription factor (genomic action) and also produces a quick non-genomic reaction through intracellular signaling pathways. The membrane associated ER (mER) may regulate both these signals and hormone therapy resistance. However, the details remain unclear because a reliable method to distinguish the signals induced by the estradiol (E2)-mER and E2-nuclear ER complex has not been established. In the present study, we prepared the novel ligand Qdot-6-E2, selective for mER, by coupling E2 with insoluble quantum dot nano-beads. We investigated the characteristics of mER signaling pathways and its contribution to hormone therapy resistance using different cell lines including estrogen depletion resistant (EDR) cells with different mechanisms. Qdot-6-E2 stimulated proliferation of nuclear ER-positive cells, but nuclear ER-negative cells showed no response. In addition, Qdot-6-E2 indirectly activated nuclear ER and increased mRNA expression of target genes. We confirmed that E2 was not dissociated from Qdot-6-E2 using a mammalian one-hybrid assay. We visually demonstrated that Qdot-6-E2 acts from the outside of cells. The gene expression profile induced by Qdot-6-E2-mER was different from that induced by E2-nuclear ER. The effect of anti-ER antibody, the GFP-ER fusion protein localization, and the effect of palmitoyl acyltransferase inhibitor also indicated the existence of mER. Regarding intracellular phosphorylation signaling pathways, the MAPK (Erk 1/2) and the PI3K/Akt pathways were both activated by Qdot-6-E2. In EDR cells, only nuclear ER-positive cells showed increased cell proliferation with increased localization of ERα to the membrane fraction. These findings suggested that Qdot-6-E2 reacts with ERα surrounding the cell membrane and that mER signals help the cells to survive under estrogen-depleted conditions by re-localizing the ER to use trace amounts of E2 more effectively. We expect that Qdot-6-E2 is a useful tool for studying the mER.

Angiotensin II Influences Pre-mRNA Splicing Regulation by Enhancing RBM20 Transcription Through Activation of the MAPK/ELK1 Signaling Pathway

RNA binding motif 20 (RBM20) is a key regulator of pre-mRNA splicing of titin and other genes that are associated with cardiac diseases. Hormones, like insulin, triiodothyronine (T3), and angiotensin II (Ang II), can regulate gene-splicing through RBM20, but the detailed mechanism remains unclear. This study was aimed at investigating the signaling mechanism by which hormones regulate pre-mRNA splicing through RBM20. We first examined the role of RBM20 in Z-, I-, and M-band titin splicing at different ages in wild type (WT) and RBM20 knockout (KO) rats using RT-PCR; we found that RBM20 is the predominant regulator of I-band titin splicing at all ages. Then we treated rats with propylthiouracil (PTU), T3, streptozotocin (STZ), and Ang II and evaluated the impact of these hormones on the splicing of titin, LIM domain binding 3 (Ldb3), calcium/calmodulin-dependent protein kinase II gamma (Camk2g), and triadin (Trdn). We determined the activation of mitogen-activated protein kinase (MAPK) signaling in primary cardiomyocytes treated with insulin, T3, and Ang II using western blotting; MAPK signaling was activated and RBM20 expression increased after treatment. Two downstream transcriptional factors c-jun and ETS Transcription Factor (ELK1) can bind the promoter of RBM20. A dual-luciferase activity assay revealed that Ang II, but not insulin and T3, can trigger ELK1 and thus promote transcription of RBM20. This study revealed that Ang II can trigger ELK1 through activation of MAPK signaling by enhancing RBM20 expression which regulates pre-mRNA splicing. Our study provides a potential therapeutic target for the treatment of cardiac diseases in RBM20-mediated pre-mRNA splicing.

ERK1/2 signaling induces skeletal muscle slow fiber-type switching and reduces muscular dystrophy disease severity

Mitogen-activated protein kinase (MAPK) signaling consists of an array of successively acting kinases. The extracellular signal-regulated kinases 1/2 (ERK1/2) are major components of the greater MAPK cascade that transduce growth factor signaling at the cell membrane. Here we investigated ERK1/2 signaling in skeletal muscle homeostasis and disease. Using mouse genetics, we observed that the muscle-specific expression of a constitutively active MEK1 mutant promotes greater ERK1/2 signaling that mediates fiber-type switching to a slow, oxidative phenotype with type I myosin heavy chain expression. Using a conditional and temporally regulated Cre strategy as well as Mapk1 (ERK2) and Mapk3 (ERK1) genetically targeted mice, MEK1-ERK2 signaling was shown to underlie this fast-to-slow fiber type switching in adult skeletal muscle as well as during development. Physiologic assessment of these activated MEK1-ERK1/2 mice showed enhanced metabolic activity and oxygen consumption with greater muscle fatigue resistance. Moreover, induction of MEK1-ERK1/2 signaling increased dystrophin and utrophin protein expression in a mouse model of limb-girdle muscle dystrophy and protected myofibers from damage. In summary, sustained MEK1-ERK1/2 activity in skeletal muscle produces a fast-to-slow fiber-type switch that protects from muscular dystrophy, suggesting a therapeutic approach to enhance the metabolic effectiveness of muscle and protect from dystrophic disease.

Pathways regulating the expression of the immunomodulatory protein glycodelin in non‑small cell lung cancer

Glycodelin [gene name, progesterone associated endometrial protein (PAEP)] was initially described as an immune system modulator in reproduction. Today, it is also known to be expressed in several types of cancer, including non‑small cell lung cancer (NSCLC). In this cancer type, the feasibility of its usage as a follow‑up biomarker and its potential role as an immune system modulator were described. It is assumed that NSCLC tumours secrete glycodelin to overcome immune surveillance. Therefore, targeting glycodelin might be a future approach with which to weaken the immune system defence of NSCLC tumours. In this context, it is important to understand the regulatory pathways of PAEP/glycodelin expression, as these are mostly unknown so far. In this study, we analysed the influence of several inducers and of their downstream pathways on PAEP/glycodelin expression in a human lung adenocarcinoma carcinoma (ADC; H1975) and a human lung squamous cell carcinoma (SQCC) cell line (2106T). PAEP/glycodelin expression was notably stimulated by the canonical transforming growth factor (TGF)‑β pathway in SQCC cells and the PKC signalling cascade in both cell lines. The PI3K/AKT pathway inhibited PAEP/glycodelin expression in the ADC cells and an antagonizing role towards the other investigated signalling cascades is suggested herein. Furthermore, the mitogen‑activated protein kinase kinase (MEK)/extracellular‑signal regulated kinases (ERK) pathway was, to a lesser extent, found to be associated with increased PAEP/glycodelin amounts. The phosphoinositide 3‑kinase (PI3K)/protein kinase B (AKT), MEK/ERK pathway and TGF‑β are targets of NSCLC drugs that are already approved or are currently under investigation. On the whole, the findings of this study provide evidence that inhibiting these targets affects the expression of glycodelin and its immunosuppressive effect in NSCLC tumours. Moreover, understanding the regulation of glycodelin expression may lead to the development of novel therapeutic approaches with which to weaken the immune system defence of NSCLC tumours in the future.

CGRP Receptor Signalling Pathways

Calcitonin gene-related peptide (CGRP) is a promiscuous peptide, similar to many other members of the calcitonin family of peptides. The potential of CGRP to act on many different receptors with differing affinities and efficacies makes deciphering the signalling from the CGRP receptor a challenging task for researchers.Although it is not a typical G protein-coupled receptor (GPCR), in that it is composed not just of a GPCR, the CGRP receptor activates many of the same signalling pathways common for other GPCRs. This includes the family of G proteins and a variety of protein kinases and transcription factors. It is now also clear that in addition to the initiation of cell-surface signalling, GPCRs, including the CGRP receptor, also activate distinct signalling pathways as the receptor is trafficking along the endocytic conduit.Given CGRP's characteristic of activating multiple GPCRs, we will first consider the complex of calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 1 (RAMP1) as the CGRP receptor. We will discuss the discovery of the CGRP receptor components, the molecular mechanisms controlling its internalization and post-endocytic trafficking (recycling and degradation) and the diverse signalling cascades that are elicited by this receptor in model cell lines. We will then discuss CGRP-mediated signalling pathways in primary cells pertinent to migraine including neurons, glial cells and vascular smooth muscle cells.Investigation of all the CGRP- and CGRP receptor-mediated signalling cascades is vital if we are to fully understand CGRP's role in migraine and will no doubt unearth new targets for the treatment of migraine and other CGRP-driven diseases.

Improved FGF21 Sensitivity and Restored FGF21 Signaling Pathway in High-Fat Diet/Streptozotocin-Induced Diabetic Rats After Duodenal-Jejunal Bypass and Sleeve Gastrectomy

Objective: Bariatric surgery can profoundly improve glucose and lipid metabolism in diabetic rats. Fibroblast growth factor 21 (FGF21) is an important hormone with multiple metabolic beneficial effects. Alteration in serum FGF21 level after bariatric surgery has been reported with conflicting results. Here, we investigated the effect of bariatric surgeries on FGF21 expression and sensitivity. Methods: We performed duodenal-jejunal bypass (DJB), sleeve gastrectomy (SG) and sham surgery in diabetic rats induced by high fat diet and streptozotocin. Metabolic parameters, including body weight, food intake, glucose tolerance, and lipid profiles, were monitored. FGF21 levels in both serum and liver were measured after surgery. FGF21 signaling pathway including FGF receptor 1 (FGFR1), β-klotho (KLB), and phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2) was detected in the liver and white adipose tissue (WAT). We also determined FGF21 sensitivity post-operatively by acute recombinant human FGF21 injection. Oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were conducted immediately after FGF21 injection. Serum triglyceride (TG) and non-esterified fatty acid (NEFA) were measured and the mRNA levels of early growth response 1 (Egr1) and c-Fos in the liver and WAT were detected after FGF21 injection. Results: Improvements in glucose tolerance, insulin sensitivity, and lipid profiles were observed after bariatric surgeries along with ameliorated lipid metabolism in the liver and WAT. Serum and hepatic FGF21 levels decreased in both DJB and SG groups. FGFR1 and phosphorylated ERK1/2 levels increased in both DJB and SG groups 8 weeks after surgery. The expression of KLB was downregulated only in the WAT after DJB and SG. Significant alteration of OGTT and ITT were observed after acute FGF21 administration in DJB and SG groups. Serum TG and NEFA in DJB and SG groups also decreased after FGF21 administration. And increased mRNA levels of Egr1 and c-Fos were detected in the liver and WAT after DJB and SG surgeries. Conclusions: DJB and SG surgeries can downregulate hepatic expression of FGF21, restore FGF21 signaling pathway and improve FGF21 sensitivity in high-fat diet/streptozotocin-induced diabetic rats.

Growth hormone acts along the PPARγ-FSP27 axis to stimulate lipolysis in human adipocytes

The lipolytic effects of growth hormone (GH) have been known for half a century and play an important physiological role for substrate metabolism during fasting. In addition, sustained GH-induced lipolysis is causally linked to insulin resistance. However, the underlying molecular mechanisms remain elusive. In the present study, we obtained experimental data in human subjects and used human adipose-derived stromal vascular cells (hADSCs) as a model system to elucidate GH-triggered molecular signaling that stimulates adipose tissue lipolysis and insulin resistance in human adipocytes. We discovered that GH downregulates the expression of fat-specific protein (FSP27), a negative regulator of lipolysis, by impairing the transcriptional ability of the master transcriptional regulator, peroxisome proliferator-activated receptor-γ (PPARγ) via MEK/ERK activation. Ultimately, GH treatment promotes phosphorylation of PPARγ at Ser273 and causes its translocation from nucleus to the cytosol. Surprisingly, FSP27 overexpression inhibited PPARγ Ser273 phosphorylation and promoted its nuclear retention. GH antagonist treatment had similar effects. Our study identifies a novel signaling mechanism by which GH transcriptionally induces lipolysis via the MEK/ERK pathway that acts along PPARγ-FSP27 in human adipose tissue.

Induction of early growth response gene 1 (EGR1) by endoplasmic reticulum stress is mediated by the extracellular regulated kinase (ERK) arm of the MAPK pathways

Endoplasmic reticulum (ER) stress activates three principal signaling pathways, collectively known as the unfolded protein response, leading to translational and transcriptional control mechanisms that dictate the cell's response as adaptive or apoptotic. The present study illustrates that for HepG2 human hepatocellular carcinoma cells the signaling pathways triggered by ER stress extend beyond the three principal pathways to include mitogen-activated protein kinase (MAPK) signaling, leading to activation of transcription from the early growth response 1 (EGR1) gene. Analysis provided evidence for a SRC-RAS-RAF-MEK-ERK cascade mechanism that leads to enhanced phosphorylation of the transcription factor ELK1. ELK1 and serum response factor (SRF) are constitutively bound to the EGR1 promoter and are phosphorylated by nuclear localized ERK. The promoter abundance of both phospho-SRF and phopsho-ELK1 was increased by ER stress, but the SRF phosphorylation was transient. Knockdown of ELK1 had little effect on the basal EGR1 mRNA content, but completely blocked the increase in response to ER stress. Conversely, knockdown of SRF suppressed basal EGR1 mRNA content, but had only a small effect on the induction by ER stress. This research highlights the importance of MAPK signaling in response to ER stress and identifies ELK1 as a transcriptional mediator and the EGR1 gene as a target.

Curcumin inhibits autocrine growth hormone-mediated invasion and metastasis by targeting NF-κB signaling and polyamine metabolism in breast cancer cells

Curcumin is assumed to be a plant-derived therapeutic drug that triggers apoptotic cell death in vitro and in vivo by affecting different molecular targets such as NF-κB. Phase I/II trial of curcumin alone or with chemotherapeutic drugs has been accomplished in pancreatic, colon, prostate and breast cancer cases. Recently, autocrine growth hormone (GH) signaling-induced cell growth, metastasis and drug resistance have been demonstrated in breast cancer. In this study, our aim was to investigate the potential therapeutic effect of curcumin by evaluating the molecular machinery of curcumin-triggered apoptotic cell death via focusing on NF-κB signaling and polyamine (PA) metabolism in autocrine GH-expressing MCF-7, MDA-MB-453 and MDA-MB-231 breast cancer cells. For this purpose, a pcDNA3.1 (+) vector with a GH gene insert was transfected by a liposomal agent in all breast cancer cells and then selection was conducted in neomycin (G418) included media. Autocrine GH-induced curcumin resistance was overcome in a dose-dependent manner and curcumin inhibited cell proliferation, invasion-metastasis and phosphorylation of p65 (Ser536), and thereby partly prevented its DNA binding activity in breast cancer cells. Moreover, curcumin induced caspase-mediated apoptotic cell death by activating the PA catabolic enzyme expressions, which led to generation of toxic by-products such as H₂O₂ in MCF-7, MDA-MB-453 and MDA-MB-231 GH+ breast cancer cells. In addition, transient silencing of SSAT prevented curcumin-induced cell viability loss and apoptotic cell death in each breast cancer cells. In conclusion, curcumin could overcome the GH-mediated resistant phenotype via modulating cell survival, death-related signaling routes and activating PA catabolic pathway.

Molecular profiling and combinatorial activity of CCT068127: a potent CDK2 and CDK9 inhibitor

Deregulation of the cyclin-dependent kinases (CDKs) has been implicated in the pathogenesis of multiple cancer types. Consequently, CDKs have garnered intense interest as therapeutic targets for the treatment of cancer. We describe herein the molecular and cellular effects of CCT068127, a novel inhibitor of CDK2 and CDK9. Optimized from the purine template of seliciclib, CCT068127 exhibits greater potency and selectivity against purified CDK2 and CDK9 and superior antiproliferative activity against human colon cancer and melanoma cell lines. X-ray crystallography studies reveal that hydrogen bonding with the DFG motif of CDK2 is the likely mechanism of greater enzymatic potency. Commensurate with inhibition of CDK activity, CCT068127 treatment results in decreased retinoblastoma protein (RB) phosphorylation, reduced phosphorylation of RNA polymerase II, and induction of cell cycle arrest and apoptosis. The transcriptional signature of CCT068127 shows greatest similarity to other small-molecule CDK and also HDAC inhibitors. CCT068127 caused a dramatic loss in expression of DUSP6 phosphatase, alongside elevated ERK phosphorylation and activation of MAPK pathway target genes. MCL1 protein levels are rapidly decreased by CCT068127 treatment and this associates with synergistic antiproliferative activity after combined treatment with CCT068127 and ABT263, a BCL2 family inhibitor. These findings support the rational combination of this series of CDK2/9 inhibitors and BCL2 family inhibitors for the treatment of human cancer.

A growth hormone receptor SNP promotes lung cancer by impairment of SOCS2-mediated degradation

Both humans and mice lacking functional growth hormone (GH) receptors are known to be resistant to cancer. Further, autocrine GH has been reported to act as a cancer promoter. Here we present the first example of a variant of the GH receptor (GHR) associated with cancer promotion, in this case lung cancer. We show that the GHRP495T variant located in the receptor intracellular domain is able to prolong the GH signal in vitro using stably expressing mouse pro-B-cell and human lung cell lines. This is relevant because GH secretion is pulsatile, and extending the signal duration makes it resemble autocrine GH action. Signal duration for the activated GHR is primarily controlled by suppressor of cytokine signalling 2 (SOCS2), the substrate recognition component of the E3 protein ligase responsible for ubiquitinylation and degradation of the GHR. SOCS2 is induced by a GH pulse and we show that SOCS2 binding to the GHR is impaired by a threonine substitution at Pro 495. This results in decreased internalisation and degradation of the receptor evident in TIRF microscopy and by measurement of mature (surface) receptor expression. Mutational analysis showed that the residue at position 495 impairs SOCS2 binding only when a threonine is present, consistent with interference with the adjacent Thr494. The latter is key for SOCS2 binding, together with nearby Tyr487, which must be phosphorylated for SOCS2 binding. We also undertook nuclear magnetic resonance spectroscopy approach for structural comparison of the SOCS2 binding scaffold Ile455-Ser588, and concluded that this single substitution has altered the structure of the SOCS2 binding site. Importantly, we find that lung BEAS-2B cells expressing GHRP495T display increased expression of transcripts associated with tumour proliferation, epithelial-mesenchymal transition and metastases (TWIST1, SNAI2, EGFR, MYC and CCND1) at 2 h after a GH pulse. This is consistent with prolonged GH signalling acting to promote cancer progression in lung cancer.

Egr-1 regulates RTA transcription through a cooperative involvement of transcriptional regulators

Kaposi's sarcoma associated herpesvirus (KSHV) regulates the host cellular environment to establish life-long persistent infection by manipulating cellular signaling pathways, with approximately 1- 5% of cells undergoing lytic reactivation during the course of infection. Egr-1 (Early Growth Response Factor-1) is one such cellular transcription factor, which gets phosphorylated during the lytic phase of viral life cycle to perpetrate its function. This study demonstrates the mechanism of how Egr-1 mediates transcription of the immediate early gene, RTA (Replication and transcription activator), which is the lytic switch gene of KSHV. Egr-1 depleted KSHV infected cells exhibited reduced expression of RTA. Also, an increase in Egr-1 phosphorylation led to a higher virion production, which was suppressed in the presence of p38 and Raf inhibitors. Reporter assays showed that coexpression of Egr-1 and CBP (CREB-binding protein) enhances RTA promoter activity as compared to the expression of either Egr-1 or CBP alone. Binding of Egr-1 and CBP at RTA promoter was analyzed by chromatin immunoprecipitation assay (ChIP), which showed an enhanced accumulation during viral reactivation. Mutation in Egr-1 binding site of the RTA promoter eliminated Egr-1 response on promoter activation. Furthermore, de novo infection of THP-1 (monocytic) and HUVECs (endothelial) cells showed an upregulation of Egr-1 phosphorylation, whereas depletion of Egr-1 reduced the mRNA levels of RTA during primary infection. Together, these results demonstrate a cooperative role of Egr-1 and CBP in mediating RTA transcription, which significantly improves our understanding of the involvement of cellular factors controlling RTA transcription in KSHV pathogenesis.

β1-Integrin Deletion From the Lens Activates Cellular Stress Responses Leading to Apoptosis and Fibrosis

Purpose

Previous research showed that the absence of β1-integrin from the mouse lens after embryonic day (E) 13.5 (β1MLR10) leads to the perinatal apoptosis of lens epithelial cells (LECs) resulting in severe microphthalmia. This study focuses on elucidating the molecular connections between β1-integrin deletion and this phenotype.

Methods

RNA sequencing was performed to identify differentially regulated genes (DRGs) in β1MLR10 lenses at E15.5. By using bioinformatics analysis and literature searching, Egr1 (early growth response 1) was selected for further study. The activation status of certain signaling pathways (focal adhesion kinase [FAK]/Erk, TGF-β, and Akt signaling) was studied via Western blot and immunohistochemistry. Mice lacking both β1-integrin and Egr1 genes from the lenses were created (β1MLR10/Egr1-/-) to study their relationship.

Results

RNA sequencing identified 120 DRGs that include candidates involved in the cellular stress response, fibrosis, and/or apoptosis. Egr1 was investigated in detail, as it mediates cellular stress responses in various cell types, and is recognized as an upstream regulator of numerous other β1MLR10 lens DRGs. In β1MLR10 mice, Egr1 levels are elevated shortly after β1-integrin loss from the lens. Further, pErk1/2 and pAkt are elevated in β1MLR10 LECs, thus providing the potential signaling mechanism that causes Egr1 upregulation in the mutant. Indeed, deletion of Egr1 from β1MLR10 lenses partially rescues the microphthalmia phenotype.

Conclusions

β1-integrin regulates the appropriate levels of Erk1/2 and Akt phosphorylation in LECs, whereas its deficiency results in the overexpression of Egr1, culminating in reduced cell survival. These findings provide insight into the molecular mechanism underlying the microphthalmia observed in β1MLR10 mice.

Growth Hormone differentially modulates chemoresistance in human endometrial adenocarcinoma cell lines

Growth Hormone may influence neoplastic development of endometrial epithelium towards endometrial adenocarcinoma, which is one of the most occurring tumors in acromegalic patients. Since chemoresistance often develops in advanced endometrial adenocarcinoma, we investigated whether Growth Hormone might influence the development of chemoresistance to drugs routinely employed in endometrial adenocarcinoma treatment, such as Doxorubicin, Cisplatin, and Paclitaxel. Growth Hormone and Growth Hormone receptor expression was assessed by immunofluorescence in two endometrial adenocarcinoma cell lines, AN3 CA and HEC-1-A cells. Growth Hormone effects were assessed investigating cell viability, caspase3/7 activation, ERK1/2, and protein kinase C delta protein expression. AN3 CA and HEC-1-A cells display Growth Hormone and Growth Hormone receptor. Growth Hormone does not influence cell viability in both cells lines, but significantly reduces caspase 3/7 activation in AN3 CA cells, an effect blocked by a Growth Hormone receptor antagonist. Growth Hormone rescues AN3 CA cells from the inhibitory effects of Doxorubicin and Cisplatin on cell viability, while it has no effect on Paclitaxel. Growth Hormone does not influence the pro-apoptotic effects of Doxorubicin, but is capable of rescuing AN3 CA cells from the pro-apoptotic effects of Cisplatin. On the other hand, Growth Hormone did not influence the effects of Doxorubicin and Paclitaxel on HEC-1A cell viability. The protective action of Growth Hormone towards the effects of Doxorubicin may be mediated by ERK1/2 activation, while the pro-apoptotic effects of Cisplatin may be mediated by protein kinase C delta inhibition. All together our results indicate that Growth Hormone may differentially contribute to endometrial adenocarcinoma chemoresistance. This may provide new insights on novel therapies against endometrial adenocarcinoma chemoresistant aggressive tumors.

The essentiality of arachidonic acid in addition to docosahexaenoic acid for brain growth and function

The essentiality of arachidonic acid (ARA) and docosahexaenoic acid (DHA) for growth and brain function using delta-6-desaturase knockout (D6D-KO) mice and a novel artificial rearing method was investigated. Newborn male wild type (WT) and homozygous D6D-KO pups were separated from their dams within 48h and fed artificial milk containing α-linolenic acid and linoleic acid (Cont), or supplemented with ARA, DHA or both (ARA+DHA). After weaning, each group was fed diets similar to artificial milk in fatty acid composition for 7 weeks. KO-Cont showed a lower body weight than WT-Cont. When ARA was added to the control diet, (KO-ARA and KO-ARA+DHA diets) the body weight gain was restored. The KO-DHA group was initially similar to the WT groups for the first 6 weeks, but afterwards their body weight was significantly lower. Brain weight in the 10 week old KO-ARA+DHA group was significantly higher within the KO dietary groups. Motor activity of the KO-ARA and KO-ARA+DHA groups was elevated relative to the KO-Cont group but the KO-ARA+DHA group exhibited similar activity to the WT-Cont group. In the motor coordination ability test, the KO-Cont group performed significantly worse compared with the WT-Cont group. KO-ARA mice showed decreased motor coordination in spite of their increased motor activity. The best performance was observed in only KO-ARA+DHA mice. These experiments demonstrated that supplementation with only ARA or only DHA was insufficient for optimal development. ARA was essential for normal growth within the lactation period. In conclusion, only the combination of preformed ARA and DHA was capable of improving the dysfunction caused by D6D deficiency.

A computationally identified compound antagonizes excess FGF-23 signaling in renal tubules and a mouse model of hypophosphatemia

Fibroblast growth factor-23 (FGF-23) interacts with a binary receptor complex composed of α-Klotho (α-KL) and FGF receptors (FGFRs) to regulate phosphate and vitamin D metabolism in the kidney. Excess FGF-23 production, which causes hypophosphatemia, is genetically inherited or occurs with chronic kidney disease. Among other symptoms, hypophosphatemia causes vitamin D deficiency and the bone-softening disorder rickets. Current therapeutics that target the receptor complex have limited utility clinically. Using a computationally driven, structure-based, ensemble docking and virtual high-throughput screening approach, we identified four novel compounds predicted to selectively inhibit FGF-23-induced activation of the FGFR/α-KL complex. Additional modeling and functional analysis found that Zinc13407541 bound to FGF-23 and disrupted its interaction with the FGFR1/α-KL complex; experiments in a heterologous cell expression system showed that Zinc13407541 selectivity inhibited α-KL-dependent FGF-23 signaling. Zinc13407541 also inhibited FGF-23 signaling in isolated renal tubules ex vivo and partially reversed the hypophosphatemic effects of excess FGF-23 in a mouse model. These chemical probes provide a platform to develop lead compounds to treat disorders caused by excess FGF-23.

Growth hormone biases amygdala network activation after fear learning

Prolonged stress exposure is a risk factor for developing posttraumatic stress disorder, a disorder characterized by the 'over-encoding' of a traumatic experience. A potential mechanism by which this occurs is through upregulation of growth hormone (GH) in the amygdala. Here we test the hypotheses that GH promotes the over-encoding of fearful memories by increasing the number of neurons activated during memory encoding and biasing the allocation of neuronal activation, one aspect of the process by which neurons compete to encode memories, to favor neurons that have stronger inputs. Viral overexpression of GH in the amygdala increased the number of amygdala cells activated by fear memory formation. GH-overexpressing cells were especially biased to express the immediate early gene c-Fos after fear conditioning, revealing strong autocrine actions of GH in the amygdala. In addition, we observed dramatically enhanced dendritic spine density in GH-overexpressing neurons. These data elucidate a previously unrecognized autocrine role for GH in the regulation of amygdala neuron function and identify specific mechanisms by which chronic stress, by enhancing GH in the amygdala, may predispose an individual to excessive fear memory formation.

Src tyrosine kinase mediates endothelin-1-induced early growth response protein-1 expression via MAP kinase-dependent pathways in vascular smooth muscle cells

We have previously demonstrated that the non-receptor protein tyrosine kinase (NR-PTK) c-Src is an upstream regulator of endothelin-1 (ET-1) and angiotensin II-induced activation of protein kinase B (PKB) signaling in vascular smooth muscle cells (VSMCs). We have also demonstrated that ET-1 potently induces the expression of the early growth response protein-1 (Egr-1), a zinc finger transcription factor that is overexpressed in models of vascular diseases, such as atherosclerosis. However, the involvement of c-Src in ET-1‑induced Egr-1 expression has not yet been investigated and its role in mitogen-activated protein kinase (MAPK) signaling remains controversial. Therefore, the aim of the present study was to examine the role of c-Src in the ET-1-induced phosphorylation of extracellular signal-regulated kinase (ERK)1/2, c-Jun N-terminal kinase (JNK) and p38 MAPK, 3 key members of the MAPK family and in the regulation of Egr-1 expression in rat aortic A10 VSMCs. ET-1 rapidly induced the phosphorylation of MAPKs, as well as the expression of Egr-1; however, treatment of the VSMCs with PP2, a specific pharmacological inhibitor of c-Src, dose-dependently reduced the phosphorylation of the 3 MAPKs and the expression of Egr-1 induced by ET-1. Furthermore, in mouse embryonic fibroblasts (MEFs) deficient in c-Src (SYF), the ET-1-induced Egr-1 expression and MAPK phosphorylation were significantly suppressed, as compared to MEFs expressing normal Src levels. These results suggest that c-Src plays a critical role in mediating ET-1-induced MAPK phosphorylation and Egr-1 expression in VSMCs.

Growth hormone signaling pathways

Over 20years ago, our laboratory showed that growth hormone (GH) signals through the GH receptor-associated tyrosine kinase JAK2. We showed that GH binding to its membrane-bound receptor enhances binding of JAK2 to the GHR, activates JAK2, and stimulates tyrosyl phosphorylation of both JAK2 and GHR. The activated JAK2/GHR complex recruits a variety of signaling proteins, thereby initiating multiple signaling pathways and cellular responses. These proteins and pathways include: 1) Stat transcription factors implicated in the expression of multiple genes, including the gene encoding insulin-like growth factor 1; 2) Shc adapter proteins that lead to activation of the grb2-SOS-Ras-Raf-MEK-ERK1,2 pathway; 3) insulin receptor substrate proteins implicated in the phosphatidylinositol-3-kinase and Akt pathway; 4) signal regulatory protein α, a transmembrane scaffold protein that recruits proteins including the tyrosine phosphatase SHP2; and 5) SH2B1, a scaffold protein that can activate JAK2 and enhance GH regulation of the actin cytoskeleton. Our recent work has focused on the function of SH2B1. We have shown that SH2B1β is recruited to and phosphorylated by JAK2 in response to GH. SH2B1 localizes to the plasma membrane, cytoplasm and focal adhesions; it also cycles through the nucleus. SH2B1 regulates the actin cytoskeleton and promotes GH-dependent motility of RAW264.7 macrophages. Mutations in SH2B1 have been found in humans exhibiting severe early-onset childhood obesity and insulin resistance. These mutations impair SH2B1 enhancement of GH-induced macrophage motility. As SH2B1 is expressed ubiquitously and is also recruited to a variety of receptor tyrosine kinases, our results raise the possibility that effects of SH2B1 on the actin cytoskeleton in various cell types, including neurons, may play a role in regulating body weight.

Growth hormone is permissive for neoplastic colon growth

Growth hormone (GH) excess in acromegaly is associated with increased precancerous colon polyps and soft tissue adenomas, whereas short-stature humans harboring an inactivating GH receptor mutation do not develop cancer. We show that locally expressed colon GH is abundant in conditions predisposing to colon cancer and in colon adenocarcinoma-associated stromal fibroblasts. Administration of a GH receptor (GHR) blocker in acromegaly patients induced colon p53 and adenomatous polyposis coli (APC), reversing progrowth GH signals. p53 was also induced in skin fibroblasts derived from short-statured humans with mutant GHR. GH-deficient prophet of pituitary-specific positive transcription factor 1 (Prop1)(-/-) mice exhibited induced colon p53 levels, and cross-breeding them with Apc(min+/-) mice that normally develop intestinal and colon tumors resulted in GH-deficient double mutants with markedly decreased tumor number and size. We also demonstrate that GH suppresses p53 and reduces apoptosis in human colon cell lines as well as in induced human pluripotent stem cell-derived intestinal organoids, and confirm in vivo that GH suppresses colon mucosal p53/p21. GH excess leads to decreased colon cell phosphatase and tensin homolog deleted on chromosome 10 (PTEN), increased cell survival with down-regulated APC, nuclear β-catenin accumulation, and increased epithelial-mesenchymal transition factors and colon cell motility. We propose that GH is a molecular component of the "field change" milieu permissive for neoplastic colon growth.

Expression, regulation and function of Egr1 during implantation and decidualization in mice

Abstract Early growth response gene 1 (Egr1), a zinc finger transcriptional factor, plays an important role in regulating cell proliferation, differentiation and angiogenesis. Current data have shown that Egr1 is involved in follicular development, ovulation, luteinization and placental angiogenesis. However, the expression, regulation and function of Egr1 in mouse uterus during embryo implantation and decidualization are poorly understood. Here we showed that Egr1 was strongly expressed in the subluminal stroma surrounding the implanting blastocyst on day 5 of pregnancy. Injection of Egr1 siRNA into the mouse uterine horn could obviously reduce the number of implanted embryos and affect the uterine vascular permeability. Further study found that Egr1 played a role through influencing the expression of cyclooxygenase-2 (Cox-2), microsomal prostaglandin E synthase 1 (mPGES-1), vascular endothelial growth factor (Vegf), transformation related protein 53 (Trp53) and matrix metallopeptidase 9 (Mmp9) genes in the process of mouse embryo implantation. Growth hormone (GH) and insulin-like growth factor 1 (IGF-1) might direct the expression of Egr1 in the uterine stromal cells. Under in vivo and in vitro artificial decidualization, Egr1 expression was significantly decreased. Overexpression of Egr1 downregulated the expression of decidual marker decidual/trophoblast PRL-related protein (Dtprp) in the uterine stromal cells, while inhibition of Egr1 upregulated the expression of Dtprp under in vitro decidualization. Estrogen and progesterone could regulate the expression of Egr1 in the ovariectomized mouse uterus and uterine stromal cells. These results suggest that Egr1 may be essential for embryo implantation and decidualization.

The oncogenic FIP1L1-PDGFRα fusion protein displays skewed signaling properties compared to its wild-type PDGFRα counterpart

Aberrant activation of oncogenic kinases is frequently observed in human cancers, but the underlying mechanism and resulting effects on global signaling are incompletely understood. Here, we demonstrate that the oncogenic FIP1L1-PDGFRα kinase exhibits a significantly different signaling pattern compared to its PDGFRα wild type counterpart. Interestingly, the activation of primarily membrane-based signal transduction processes (such as PI3-kinase- and MAP-kinase- pathways) is remarkably shifted toward a prominent activation of STAT factors. This diverging signaling pattern compared to classical PDGF-receptor signaling is partially coupled to the aberrant cytoplasmic localization of the oncogene, since membrane targeting of FIP1L1-PDGFRα restores activation of MAPK- and PI3K-pathways. In stark contrast to the classical cytokine-induced STAT activation process, STAT activation by FIP1L1-PDGFRα does neither require Janus kinase activity nor Src kinase activity. Furthermore, we investigated the mechanism of STAT5 activation via FIP1L1-PDGFRα in more detail and found that STAT5 activation does not involve an SH2-domain-mediated binding mechanism. We thus demonstrate that STAT5 activation occurs via a non-canonical activation mechanism in which STAT5 may be subject to a direct phosphorylation by FIP1L1-PDGFRα.

Neurotrophic tyrosine kinase receptor 1 is a direct transcriptional and epigenetic target of IL-13 involved in allergic inflammation

Although interleukin (IL)-13 and neurotrophins are functionally important for the pathogenesis of immune responses, the interaction of these pathways has not been explored. Herein, by interrogating IL-13-induced responses in human epithelial cells we show that neurotrophic tyrosine kinase receptor, type 1 (NTRK1), a cognate, high-affinity receptor for nerve growth factor (NGF), is an early transcriptional IL-13 target. Induction of NTRK1 was accompanied by accumulation of activating epigenetic marks in the promoter; transcriptional and epigenetic changes were signal transducer and activator of transcription 6 dependent. Using eosinophilic esophagitis as a model for human allergic inflammation, we found that NTRK1 was increased in inflamed tissue and dynamically expressed as a function of disease activity and that the downstream mediator of NTRK1 signaling early growth response 1 protein was elevated in allergic inflammatory tissue compared with control tissue. Unlike NTRK1, its ligand NGF was constitutively expressed in control and disease states, indicating that IL-13-stimulated NTRK1 induction is a limiting factor in pathway activation. In epithelial cells, NGF and IL-13 synergistically induced several target genes, including chemokine (C-C motif) ligand 26 (eotaxin-3). In summary, we have demonstrated that IL-13 confers epithelial cell responsiveness to NGF by regulating NTRK1 levels by a transcriptional and epigenetic mechanism and that this process likely contributes to allergic inflammation.

A cell-based sensor of fluid shear stress for microfluidics

Microsystems designed for cell-based studies or applications inherently require fluid handling. Flows within such systems inevitably generate fluid shear stress (FSS) that may adversely affect cell health. Simple assays of cell viability, morphology or growth are typically reported to indicate any gross disturbances to cell physiology. However, no straightforward metric exists to specifically evaluate physiological implications of FSS within microfluidic devices, or among competing microfluidic technologies. This paper presents the first genetically encoded cell sensors that fluoresce in a quantitative fashion upon FSS pathway activation. We picked a widely used cell line (NIH3T3s) and created a transcriptional cell-sensor where fluorescence turns on when transcription of a relevant FSS-induced protein is initiated. Specifically, we chose Early Growth Factor-1 (a mechanosensitive protein) upregulation as the node for FSS detection. We verified our sensor pathway specificity and functionality by noting induced fluorescence in response to chemical induction of the FSS pathway, seen both through microscopy and flow cytometry. Importantly, we found our cell sensors to be inducible by a range of FSS intensities and durations, with a limit of detection of 2 dynes cm(-2) when applied for 30 minutes. Additionally, our cell-sensors proved their versatility by showing induction sensitivity when made to flow through an inertial microfluidic device environment with typical flow conditions. We anticipate these cell sensors to have wide application in the microsystems community, allowing the device designer to engineer systems with acceptable FSS, and enabling the end-user to evaluate the impact of FSS upon their assay of interest.

Milk-derived tripeptides IPP (Ile-Pro-Pro) and VPP (Val-Pro-Pro) promote adipocyte differentiation and inhibit inflammation in 3T3-F442A cells

Milk derived tripeptides IPP (Ile-Pro-Pro) and VPP (Val-Pro-Pro) have shown promise as anti-hypertensive agents due to their inhibitory effects on angiotensin converting enzyme (ACE). Due to the key inter-related roles of hypertension, chronic inflammation and insulin resistance in the pathogenesis of metabolic syndrome, there is growing interest in investigating established anti-hypertensive agents for their effects on insulin sensitivity and inflammation. In this study, we examined the effects of IPP and VPP on 3T3-F442A murine pre-adipocytes, a widely used model for studying metabolic diseases. We found that both IPP and VPP induced beneficial adipogenic differentiation as manifested by intracellular lipid accumulation, upregulation of peroxisome proliferator-activated receptor gamma (PPARγ) and secretion of the protective lipid hormone adiponectin by these cells. The observed effects were similar to those induced by insulin, suggesting potential benefits in the presence of insulin resistance. IPP and VPP also inhibited cytokine induced pro-inflammatory changes such as reduction in adipokine levels and activation of the nuclear factor kappa B (NF-κB) pathway. Taken together, our findings suggest that IPP and VPP exert insulin-mimetic adipogenic effects and prevent inflammatory changes in adipocytes, which may offer protection against metabolic disease.

Elafin drives poor outcome in high-grade serous ovarian cancers and basal-like breast tumors

High-grade serous ovarian carcinoma (HGSOC) and basal-like breast cancer (BLBC) share many features including TP53 mutations, genomic instability and poor prognosis. We recently reported that Elafin is overexpressed by HGSOC and is associated with poor overall survival. Here, we confirm that Elafin overexpression is associated with shorter survival in 1000 HGSOC patients. Elafin confers a proliferative advantage to tumor cells through the activation of the MAP kinase pathway. This mitogenic effect can be neutralized by RNA interference, specific antibodies and a MEK inhibitor. Elafin expression in patient-derived samples was also associated with chemoresistance and strongly correlates with bcl-xL expression. We extended these findings into the examination of 1100 primary breast tumors and six breast cancer cell lines. We observed that Elafin is overexpressed and secreted specifically by BLBC tumors and cell lines, leading to a similar mitogenic effect through activation of the MAP kinase pathway. Here too, Elafin overexpression is associated with poor overall survival, suggesting that it may serve as a biomarker and therapeutic target in this setting.

MAPK signaling triggers transcriptional induction of cFOS during amino acid limitation of HepG2 cells

Amino acid (AA) deprivation in mammalian cells activates a collection of signaling cascades known as the AA response (AAR), which is characterized by transcriptional induction of stress-related genes, including FBJ murine osteosarcoma viral oncogene homolog (cFOS). The present study established that the signaling mechanism underlying the AA-dependent transcriptional regulation of the cFOS gene in HepG2 human hepatocellular carcinoma cells is independent of the classic GCN2-eIF2-ATF4 pathway. Instead, a RAS-RAF-MEK-ERK cascade mediates AAR signaling to the cFOS gene. Increased cFOS transcription is observed from 4-24 h after AAR-activation, exhibiting little or no overlap with the rapid and transient increase triggered by the well-known serum response. Furthermore, serum is not required for the AA-responsiveness of the cFOS gene and no phosphorylation of promoter-bound serum response factor (SRF) is observed. The ERK-phosphorylated transcription factor E-twenty six-like (p-ELK1) is increased in its association with the cFOS promoter after activation of the AAR. This research identified cFOS as a target of the AAR and further highlights the importance of AA-responsive MAPK signaling in HepG2 cells.

A mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK)-dependent transcriptional program controls activation of the early growth response 1 (EGR1) gene during amino acid limitation

Amino acid (AA) limitation in mammalian cells triggers a collection of signaling cascades jointly referred to as the AA response (AAR). In human HepG2 hepatocellular carcinoma, the early growth response 1 (EGR1) gene was induced by either AA deprivation or endoplasmic reticulum stress. AAR-dependent EGR1 activation was discovered to be independent of the well characterized GCN2-ATF4 pathway and instead dependent on MEK-ERK signaling, one of the MAPK pathways. ChIP showed that constitutively bound ELK1 at the EGR1 proximal promoter region was phosphorylated after AAR activation. Increased p-ELK1 binding was associated with increased de novo recruitment of RNA polymerase II to the EGR1 promoter. EGR1 transcription was not induced in HEK293T cells lacking endogenous MEK activity, but overexpression of exogenous constitutively active MEK in HEK293T cells resulted in increased basal and AAR-induced EGR1 expression. ChIP analysis of the human vascular endothelial growth factor A (VEGF-A) gene, a known EGR1-responsive gene, revealed moderate increases in AAR-induced EGR1 binding within the proximal promoter and highly inducible binding to a site within the first intron. Collectively, these data document a novel AA-activated MEK-ERK-ELK1 signaling mechanism.

Selective inhibition of the function of tyrosine-phosphorylated STAT3 with a phosphorylation site-specific intrabody

Signal transducer and activator of transcription 3 (STAT3) is a multifunctional protein that participates in signaling pathways initiated by various growth factors and cytokines. It exists in multiple forms including those phosphorylated on Tyr(705) (pYSTAT3) or Ser(727) (pSSTAT3) as well as the unphosphorylated protein (USTAT3). In addition to the canonical transcriptional regulatory role of pYSTAT3, both USTAT3 and pSSTAT3 function as transcriptional regulators by binding to distinct promoter sites and play signaling roles in the cytosol or mitochondria. The roles of each STAT3 species in different biological processes have not been readily amenable to investigation, however. We have now prepared an intrabody that binds specifically and with high affinity to the tyrosine-phosphorylated site of pYSTAT3. Adenovirus-mediated expression of the intrabody in HepG2 cells as well as mouse liver blocked both the accumulation of pYSTAT3 in the nucleus and the production of acute phase response proteins induced by interleukin-6. Intrabody expression did not affect the overall accumulation of pSSTAT3 induced by interleukin-6 or phorbol 12-myristate 13-acetate (PMA), the PMA-induced expression of the c-Fos gene, or the PMA-induced accumulation of pSSTAT3 specifically in mitochondria. In addition, it had no effect on interleukin-6-induced expression of the gene for IFN regulatory factor 1, a downstream target of STAT1. Our results suggest that the engineered intrabody is able to block specifically the downstream effects of pYSTAT3 without influencing those of pSSTAT3, demonstrating the potential of intrabodies as tools to dissect the cellular functions of specific modified forms of proteins that exist as multiple species.

Growth hormone potentiates 17β-estradiol-dependent breast cancer cell proliferation independently of IGF-I receptor signaling

Estrogen action in mammary gland development and breast cancer progression is tightly linked to the GH/IGF-I axis. Although many of the effects of GH on mammary gland growth and development require IGF-I, the extent to which GH action in breast cancer depends on IGF-I is not known. We examined GH action in a panel of estrogen receptor-positive breast cancer cell lines and found that T47D cells express significant levels of GH receptor and that GH significantly enhances 17β-estradiol (E2)-stimulated proliferation in these cells. GH action in the T47D cells was independent of changes in IGF-I and IGF-I receptor (IGF-IR) expression and IGF-IR signaling, suggesting that GH can exert direct effects on breast cancer cells. Although E2-dependent proliferation required IGF-IR signaling, the combination of GH+E2 overcame inhibition of IGF-IR activity to restore proliferation. In contrast, GH required both Janus kinase 2 and epidermal growth factor receptor signaling for subsequent ERK activation and potentiation of E2-dependent proliferation. Downstream of these pathways, we identified a number of immediate early-response genes associated with proliferation that are rapidly and robustly up-regulated by GH. These findings demonstrate that GH can have important effects in breast cancer cells that are distinct from IGF-IR activity, suggesting that novel drugs or improved combination therapies targeting estrogen receptor and the GH/IGF axis may be beneficial for breast cancer patients.

Mechanism of tissue-specific farnesoid X receptor in suppressing the expression of genes in bile-acid synthesis in mice

Activation of farnesoid X receptor (Fxr, Nr1h4) is a major mechanism in suppressing bile-acid synthesis by reducing the expression levels of genes encoding key bile-acid synthetic enzymes (e.g., cytochrome P450 [CYP]7A1/Cyp7a1 and CYP8B1/Cyp8b1). FXR-mediated induction of hepatic small heterodimer partner (SHP/Shp, Nr0b2) and intestinal fibroblast growth factor 15 (Fgf15; FGF19 in humans) has been shown to be responsible for this suppression. However, the exact contribution of Shp/Fgf15 to this suppression, and the associated cell-signaling pathway, is unclear. By using novel genetically modified mice, the current study showed that the intestinal Fxr/Fgf15 pathway was critical for suppressing both Cyp7a1 and Cyp8b1 gene expression, but the liver Fxr/Shp pathway was important for suppressing Cyp8b1 gene expression and had a minor role in suppressing Cyp7a1 gene expression. Furthermore, in vivo administration of Fgf15 protein to mice led to a strong activation of extracellular signal-related kinase (ERK) and, to a smaller degree, Jun N-terminal kinase (JNK) in the liver. In addition, deficiency of either the ERK or JNK pathway in mouse livers reduced the basal, but not the Fgf15-mediated, suppression of Cyp7a1 and Cyp8b1 gene expression. However, deficiency of both ERK and JNK pathways prevented Fgf15-mediated suppression of Cyp7a1 and Cyp8b1 gene expression.

CONCLUSION

The current study clearly elucidates the underlying molecular mechanism of hepatic versus intestinal Fxr in regulating the expression of genes critical for bile-acid synthesis and hydrophobicity in the liver.