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At least 1,261 records · Page 70Linked to original sources
PubMed2006

FOXOs in the maintenance of vascular homoeostasis.

The mammalian FoxO (forkhead box O) transcription factors FoxO1, FoxO3 and FoxO4 represent one of several effector arms of the PI3K (phosphoinositide 3-kinase)-Akt signalling network that has been linked to cancer, metabolism and aging. Specific roles of the FoxOs in the vascular cell types have been investigated to reveal that they play redundant yet critical roles in the proliferation and survival of ECs (endothelial cells). Somatic deletions of all FoxOs engendered progressive, widespread and highly penetrant haemangiomas associated with altered proliferative/survival dynamics of ECs in our genetic model. Related work by Akt-FoxO manipulation reported differentially regulated genes in ECs that may represent novel FoxO targets, controlling EC growth and morphogenesis and mediating many of the consequences of FoxO inactivation in the endothelium. Further studies on the action of these surrogate genes may provide important new insights into how the PI3K-Akt-FoxO pathway could be exploited clinically to treat vascular diseases and lead to the invention of novel therapeutic approaches. Here recent studies elucidating the role of FoxOs in the maintenance of vascular homoeostasis and supporting that the mammalian FoxO family serves essential roles in the maintenance of vascular stability and the suppression of aberrant vascular outgrowth are discussed.

Animals↗
PubMed2002

Regulation of Raf-Akt Cross-talk.

We have recently shown that the Ras-Raf-MEK-ERK and phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathways can cross-talk in the human breast cancer cell line MCF-7. High Raf activity induces growth arrest and differentiation in these cells, whereas high PI3K/Akt activity correlates with cell survival and proliferation. Here we show that the Raf-Akt cross-talk is regulated in a concentration- and ligand-dependent manner. High doses of insulin-like growth factor I (IGF-I) activate Akt quickly and strongly enough to suppress Raf kinase activity via phosphorylation of Ser-259, whereas low doses of IGF-I do not trigger this cross-talk but are still mitogenic. Phorbol 12-myristate 13-acetate, a differentiation-inducing stimulus, potently activates the Ras-Raf-MEK-ERK pathway but only weakly activates PI3K/Akt and does not trigger the cross-talk. Thus, the herein analyzed parameters such as ligand type, concentration, and time course may contribute to the cellular response of either proliferation or differentiation. This is highly relevant to understanding cellular transformation and may be of use in areas like tissue engineering.

Cell Division↗
PubMed2003

Stimulation of signal transducer and activator of transcription-1 (STAT1)-dependent gene transcription by lipopolysaccharide and interferon-gamma is regulated by mammalian target of rapamycin.

Mammalian target of rapamycin (mTOR) and phosphatidylinositol 3-kinase (PI3K) regulate cell growth, protein synthesis, and apoptosis in response to nutrients and mitogens. As an important source of nitric oxide during inflammation, human inducible nitric oxide synthase also plays a role in the regulation of cytokine-driven cell proliferation and apoptosis. The role of mTOR and PI3K in the activation of human inducible nitric oxide synthase transcription by cytokines and lipopolysaccharide (LPS) was investigated in lung epithelial adenocarcinoma (A549) cells. LY294002, a dual mTOR and PI3K inhibitor, blocked human inducible nitric oxide synthase (hiNOS) promoter activation and mRNA induction by cytokines and LPS in a PI3K-independent fashion. On gene expression analysis, LY294002 selectively blocked the induction of a subset of 14 LPS/interferon-gamma (IFN-gamma)-induced genes, previously characterized as signal transducer and activator of transcription-1 (STAT1)-dependent. LY294002, but not wortmannin, inhibited LPS/IFN-gamma-dependent STAT1 phosphorylation at Ser-727 and STAT1 activity. Consistent with dual inhibition of mTOR and PI3K by LY294002, dominant-negative mTOR, anti-mTOR small interfering RNA, or rapamycin each inhibited phosphorylation of STAT1 only in the presence of wortmannin. LPS/IFN-gamma led to the formation of a macromolecular complex containing mTOR, STAT1, as well as protein kinase C delta, a known STAT1alpha kinase. Thus, LPS and IFN-gamma activate the PI3K and mTOR pathways, which converge to regulate STAT1-dependent transcription of pro-apoptotic and pro-inflammatory genes in a rapamycin-insensitive manner.

Androstadienes↗
PubMed2003

Cyclin-dependent kinase-5 is involved in neuregulin-dependent activation of phosphatidylinositol 3-kinase and Akt activity mediating neuronal survival.

The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway plays an important role in mediating survival signals in wide variety of neurons and cells. Recent studies show that Akt also regulates metabolic pathways to regulate cell survival. In this study, we reported that cyclin-dependent kinase-5 (Cdk5) regulates Akt activity and cell survival through the neuregulin-mediated PI 3-kinase signaling pathway. We found that brain extracts of Cdk5-/-mice display a lower PI 3-kinase activity and phosphorylation of Akt compared with that in wild type mice. Moreover, we demonstrated that Cdk5 phosphorylated Ser-1176 in the neuregulin receptor ErbB2 and phosphorylated Thr-871 and Ser-1120 in the ErbB3 receptor. We identified the Ser-1120 sequence RSRSPR in ErbB3 as a novel phosphorylation consensus sequence of Cdk5. Finally, we found that Cdk5 activity is involved in neuregulin-induced Akt activity and neuregulin-mediated neuronal survival. These findings suggest that Cdk5 may exert a key role in promoting neuronal survival by regulating Akt activity through the neuregulin/PI 3-kinase signaling pathway.

Amino Acid Sequence↗
PubMed2003

The forkhead transcription factor FOXO4 induces the down-regulation of hypoxia-inducible factor 1 alpha by a von Hippel-Lindau protein-independent mechanism.

Tumors utilize hyperactivation of the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway to cope with deleterious environmental conditions. Activation of the PI3K/AKT pathway has been shown to increase protein expression of the alpha subunit of the hypoxia-inducible factor (HIF) 1, a key regulator of oxygen homeostasis. Elevated levels of HIF-1 alpha induce expression of genes with critical roles in angiogenesis, erythropoiesis, and glucose metabolism, processes that are essential for tumor expansion. Here we examine the involvement of FOXO4 (also known as AFX), a member of the forkhead transcription factor superfamily that is negatively regulated by the PI3K/AKT pathway, in the regulation of HIF-1 alpha protein expression. Nuclear expression of FOXO4 results in the suppression of various responses to hypoxia, including decreased vascular endothelial growth factor, glucose transporter 1, and erythropoietin expression. Interestingly, FOXO4 down-regulates the HIF-1 alpha protein levels, consistent with the lack of hypoxia responsiveness. Previous results have revealed a role for prolyl hydroxylation and resultant von Hippel-Lindau protein (pVHL) interactions in the ubiquitin-proteasome-mediated degradation of HIF-1 alpha. However, neither inhibition of prolyl hydroxylases nor mutation of HIF-1 alpha-hydroxylated prolines involved with pVHL-mediated binding inhibits the observed FOXO4-mediated down-regulation of HIF-1 alpha. These results suggest a novel alternate mechanism for hypoxic regulation that is dependent upon the level of activation of FOXO4-mediated transcription.

Blotting, Western↗
PubMed2003

Inhibition of ligand-independent ERK1/2 activity in kidney proximal tubular cells deprived of soluble survival factors up-regulates Akt and prevents apoptosis.

Mouse kidney proximal tubular epithelial (MK-PT) cells die by apoptosis over 7-10 days when deprived of all survival factors. We show here that withdrawal of all survival factors from MK-PT cells is associated with a progressive increase in the activity of extracellular signal-regulated kinase-1 and -2 (ERK1/2) and a progressive decrease in phosphorylated Akt, a kinase critical to cell survival. Pharmacological inhibition of MEK1/2, the immediate upstream kinase for ERK1/2, not only prevented the decrease in phosphorylated Akt, but also prolonged MK-PT cell survival. Inhibition of ERK1/2, by itself, in the absence of any other known survival factors, was as potent as epidermal growth factor in maintaining MK-PT cell viability. ERK1/2 co-immunoprecipitated with Akt in a multimolecular assembly of signaling molecules, containing at a minimum ERK1/2, Akt, Rsk, and 3-phosphoinositide dependent kinase 1 (PDK1). We hypothesize that the kinase Rsk, whose activation requires phosphorylation by both ERK1/2 and PDK1, acts as a bridge bringing ERK1/2 into proximity with PDK1-associated Akt. Although a number of interactions between the Raf-MEK-ERK and PI3K-Akt signaling pathways have been described, our results are the first to show modulation of Akt activity by signaling events originating with ERK1/2. Spontaneous activation of ERK1/2 occurs via MEK1/2 and appears to depend on oxidant stress, accompanying induction of the default pathway of apoptosis. Together, these data suggest that the spontaneous activation of ERK1/2, in the absence of known extracellular stimuli, represents a previously unrecognized major regulatory pathway determining the fate of cells destined to die by the default pathway of apoptosis.

Animals↗
PubMed2004

Apc deficiency is associated with increased Egfr activity in the intestinal enterocytes and adenomas of C57BL/6J-Min/+ mice.

Overexpression of the epidermal growth factor receptor (EGFR) and its increased tyrosine kinase activity are implicated in colorectal cancer (CRC) development and malignant progression. The C57BL/6J-Min/+ (Min/+) mouse is a model for CRC and develops numerous intestinal adenomas. We analyzed the normal mucosa of Min/+ and Apc+/+ (WT) littermate mice together with Apc-null adenomas to gain insight into the roles of Egfr in these intestinal tissues. Protein analyses showed that Egfr activity was highest in the tumors, and also up-regulated in Min/+ relative to WT enterocytes. Expression of ubiquitylated Egfr (Egfr-Ub) was increased in Min/+ enterocytes and tumors. Tumors exhibited increased association of Egfr with clathrin heavy chain (CHC), Gab1, and p85alpha, the regulatory subunit of phosphoinositide 3-kinase (PI3K), and tumors also overexpressed c-Src, PDK1, and Akt. Immunohistochemistry for Akt-p-Ser473 revealed a low level of this active kinase in Min/+ and WT enterocytes and its strong presence in tumors. Prostaglandin E2 (PGE2) is a product of cyclooxygenase-2 (Cox-2) activity that is up-regulated in Min/+ tumors and transactivates Egfr. PGE2 expression was significantly higher in untreated Min/+ tumors and reduced by treatment with the Cox-2 inhibitor, celecoxib. Dietary administration of this NSAID also inhibited Egfr activity in tumors. Increased activation of the EGFR-PI3K-Akt signaling pathway in tumors relative to Apc+/+ and ApcMin/+ enterocytes provides potential opportunities for therapeutic interventions to differentially suppress tumor formation, promotion, progression, and/or recurrence.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces rheumatoid arthritis synovial fibroblast proliferation through mitogen-activated protein kinases and phosphatidylinositol 3-kinase/Akt.

A hallmark of rheumatoid arthritis (RA) is the pseudo-tumoral expansion of fibroblast-like synoviocytes (FLSs), and the RA FLS has therefore been proposed as a therapeutic target. Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) has been described as a pro-apoptotic factor on RA FLSs and, therefore, suggested as a potential drug. Here we report that exposure to TRAIL-induced apoptosis in a portion (up to 30%) of RA FLSs within the first 24 h. In the cells that survived, TRAIL induced RA FLS proliferation in a dose-dependent manner, with maximal proliferation observed at 0.25 nm. This was blocked by a neutralizing anti-TRAIL antibody. RA FLSs were found to express constitutively TRAIL receptors 1 and 2 (TRAIL-R1 and TRAIL-R2) on the cell surface. TRAIL-R2 appears to be the main mediator of TRAIL-induced stimulation, as RA FLS proliferation induced by an agonistic anti-TRAIL-R2 antibody was comparable with that induced by TRAIL. TRAIL activated the mitogen-activated protein kinases ERK and p38, as well as the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway with kinetics similar to those of TNF-alpha. Moreover, TRAIL-induced RA FLS proliferation was inhibited by the protein kinase inhibitors PD98059, SB203580, and LY294002, confirming the involvement of the ERK, p38, and PI3 kinase/Akt signaling pathways. This dual functionality of TRAIL in stimulating apoptosis and proliferation has important implications for its use in the treatment of RA.

Apoptosis Regulatory Proteins↗
PubMed2004

Unoprostone isopropyl rescues retinal progenitor cells from apoptosis in vitro.

PURPOSE: Unoprostone isopropyl is an ocular hypotensive that was originally produced as a prostaglandin F2alpha analogue and is eventually recognized as a synthetic docosanoid. The compound is recently suggested to have potent neuroprotective ability in the retina. The purpose of this study is to test whether and how the biologically active metabolites of unoprostone isopropyl rescue retinal neuro-glial progenitor cells from apoptosis. METHODS: R28 cells were deprived of serum for 24 hr with or without varying concentrations of unoprostone metabolite M1 or M2 or vehicle in the presence or absence of specific inhibitors against several types of signal transduction proteins. Immunocytochemistry against activated caspase-3 with Hoechst nuclear staining was performed. RESULTS: Up to 15%of R28 cells became pyknotic and activated caspase-3 immunoreactive after 24-hr serum withdrawal. M1, but not M2, significantly reduced apoptotic cells in a dose-dependent fashion with a maximal effect at 100 microM (p < .0001). LY294002, the phosphatidylinositol 3-OH kinase (PI3K) inhibitor, and KT5823, the protein kinase G (PKG) inhibitor, reversed the antiapoptotic effect of M1. CONCLUSIONS: The unoprostone metabolite M1 protects retinal neuro-glial progenitor R28 cells from apoptosis induced by serum deprivation via the PI3K and PKG pathways.

Animals↗
PubMed2005

Role of leptin in modulation of Porphyromonas gingivalis lipopolysaccharide-induced up-regulation of endothelin-1 in salivary gland acinar cells.

Leptin, a pleiotropic cytokine that regulates food intake and metabolic and endocrine responses, has emerged recently as an important regulator of mucosal inflammatory responses to bacterial infection. In this study, we report that in sublingual salivary gland acinar cells leptin plays a role in the suppression of up-regulation in endothelin-1 (ET-1), induced by the LPS of a periodontopathic bacterium P. gingivalis. We show that P. gingivalisLPS detrimental effect on salivary mucin synthesis, associated with up-regulation (3.9-fold) in ET-1 generation and the enhancement (3.2-fold) in endothelin-converting enzyme-1 (ECE-1) activity, was subject to a dose-dependent suppression by leptin. The impedance by leptin of the LPS inhibitory effect on mucin synthesis was blocked by wortmannin, an inhibitor of PI3K, as well as by ERK inhibitor, PD98059. However, while the blockade of ERK led also to amplification in the impedance by leptin of the LPS-induced expression of ECE-1 and ET-1, the effect was not observed in the presence of wortmannin. The findings are the first to demonstrate that leptin counters the pathological consequences of P. gingivalisinfection on the synthesis of salivary mucin through the involvement in signaling events of PI3K and ERK pathways. We also show that the ERK cascade represents a critical signaling target for leptin in the LPS-induced up-regulation in ET-1.

Analysis of Variance↗
PubMed2000

Impairment of erbB1 receptor and fluid-phase endocytosis and associated mitogenic signaling by inositol hexaphosphate in human prostate carcinoma DU145 cells.

Recently, we observed that epidermal growth factor receptor (EGFR or erbB1) endocytosis and associated mitogenic signaling occur in human prostate cancer (PCA) cells, suggesting that erbB1 endocytosis might be involved in advanced and androgen-independent PCA growth. Based on these findings, and the fact that aberrant expression of erbB family members is common in human prostatic intraepithelial neoplasia and invasive PCA, we reasoned that impairment of erbB1 endocytosis and associated mitogenic signaling might inhibit PCA growth. Inositol hexaphosphate (IP6) interacts with plasma membrane clathrin-associated protein complex 2 (AP2) and inhibits phosphatidylinositol 3-kinase (PI3K). As these are essential components of receptor-mediated and fluid-phase endocytosis, respectively, we reasoned that IP6 might impair erbB1 endocytosis and associated signaling in human PCA cells, leading to their growth inhibition. IP6 strongly to completely inhibited (26-100%; P < 0.05) transforming growth factor alpha-induced binding of activated erbB1 to AP2 in human PCA DU145 cells, demonstrating the impairment of the initial step in ligand-induced erbB1 endocytosis. IP6 treatment of cells resulted in a dose-dependent increase (1.8- to 7. 7-fold compared with cells treated with ligand alone; P < 0.05) in levels of activated erbB1. These two findings suggest that the inhibitory effect of IP6 on receptor endocytosis is independent of its lack of effect on ligand-induced erbB1 activation. These effects of IP6, however, were associated with strong inhibition of ligand-induced Shc phosphorylation (77-84% decrease; P < 0.05) and its binding to erbB1 (58-100% decrease; P < 0.05). IP6 also significantly and dose-dependently inhibited fluid-phase endocytosis (19-52%; P < 0.05). It inhibited PI3K-AKT signaling pathway as an upstream response in its effect on the inhibition of fluid-phase endocytosis. The inhibition of erbB1 receptor and fluid-phase endocytosis, and associated signaling by IP6, was corroborated by very strong to complete inhibition (70-100%; P < 0.05) of extracellular signal-regulated protein kinase 1/2 activation by IP6. IP6 significantly (P < 0.05) inhibited anchorage-dependent and -independent inhibition (50-100% and 30-75%, respectively) in DU145 cells. Targeting the impairment of erbB1 endocytosis and associated mitogenic signaling by IP6 in advanced and androgen-independent human PCA DU145 cells could be a useful approach for treating PCA.

Adaptor Protein Complex 2↗
PubMed2006

AIB1 promotes DNA replication by JNK repression and AKT activation during cellular stress.

Amplified in breast cancer 1 (AIB1) is a member of the p160 family of nuclear receptor coactivator protein. Recent studies have reported that high-level AIB1 production is involved in the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway for progression to malignant carcinoma in a steroid-independent manner. Here we demonstrate that, in AIB1-knockout DT40 chicken B-lymphocytes, loss of AIB1 results in induction of phosphorylation of c-Jun N-terminal kinase (JNK) and c-Jun, in addition to the inhibition of DNA replication. In contrast, high-level AIB1 production prevents proapoptotic activation of the JNK/c-Jun signal transduction pathway and induces DNA replication through phosphorylation of the Akt/p65 NF-kappaB subunit RelA under cellular stresses such as UV irradiation or serum deprivation. Moreover, we have found that AIB1 is essential for the phosphorylation of histone H3 at serine 10, which is associated with the signal transduction to chromatin, leading to the transient expression of immediate-early genes in response to UV stimulation. Our results therefore suggest that AIB1 directly links to cell cycle control mechanisms in concern with the balance between apoptosis and proliferation.

Animals↗
PubMed2006

PI3K, RSK, and mTOR signal networks for the GST gene regulation.

The induction of glutathione S-transferases (GST) represents not only cell detoxification and survival but also cancer prevention. In response to various extracellular stimuli, expression of the gene has been shown to be regulated coordinately by activating the transcription factors in a transcriptional or posttranscriptional manner. Cytoprotective agents induce GST and concomitantly activate the PI3K-Akt/ERK-RSK1-mTOR pathways that activate the transcription factors favoring cell viability. The mechanistic basis and cell signaling for the induction of GST induction by prooxidants and toxicants may be different from that by cytoprotective agents. This paper summarizes the molecular mechanisms of the transcriptional induction of the GST gene orchestrated by a series of transcription factors that recruit coactivators or corepressors.

Animals↗
PubMed2005

Akt/FOXO3a signaling modulates the endothelial stress response through regulation of heat shock protein 70 expression.

To identify new antiapoptotic targets of the PI3K-Akt signaling pathway in endothelial cells, adenovirus-mediated Akt1 gene transfer and oligonucleotide microarrays were used to examine Akt-regulated transcripts. DNA microarray analysis revealed that HSP70 expression underwent the greatest fold activation of 12,532 transcripts examined in human umbilical vein endothelial cells (HUVEC) transduced with constitutively active Akt1. Akt1 gene transfer increased HSP70 transcript expression by 24.8-fold as determined by quantitative PCR and promoted a dose-dependent up-regulation of HSP70 protein as determined by Western immunoblot analysis. Gene transfer of FOXO3a, a downstream target of Akt in endothelial cells, significantly suppressed both basal and stress-induced HSP70 protein expression. FOXO3a induced caspase-9-dependent apoptosis in HUVEC, and cotransduction with Ad-HSP70 rescued endothelial cells from FOXO3a-induced apoptosis under basal and stress conditions. Our results identify HSP70 as a new antiapoptotic target of Akt-FOXO3a signaling in endothelial cells that controls viability through modulation of the stress-induced intrinsic cell death pathway.

Adenoviridae↗
PubMed2003

Phosphorylated Akt/PKB controls cell growth and apoptosis in intraductal papillary-mucinous tumor and invasive ductal adenocarcinoma of the pancreas.

INTRODUCTION: Akt/PKB promotes cell proliferation and rescues cells from apoptosis. AIM: To evaluate the role of Akt/PKB, a key molecule in phosphatidylinositol 3-OH kinase (PI3K) signaling, during the development of pancreatic duct neoplasias such as intraductal papillary-mucinous tumor (IPMT) and invasive ductal adenocarcinoma (IDAC) of the pancreas. METHODOLOGY AND RESULTS: In PK-45H pancreatic cancer cells, the growth-inhibitory and apoptosis-inducing effects of LY294002, a PI3K inhibitor, were detected in a concentration-dependent manner, followed by the reduction of phosphorylated Akt levels. Immunohistochemical analyses revealed that frequent overexpression of phosphorylated Akt (Ser473) was detected in 10 (63%) of 16 IPMTs and 14 (70%) of 20 IDACs. It is interesting that the incidence of Akt phosphorylation closely correlated with Ki-67 immunoreactivity and had an inverse association with the number of cases of apoptotic bodies in both IPMT and IDAC. Although there was no good correlation with other clinicopathologic parameters, the two patients with recurrent IPMT had high levels of phosphorylated Akt. CONCLUSION: Our findings suggest that activation of Akt plays an important role during the progression of these pancreatic duct neoplasias at the early stage. Furthermore, inhibition of the PI3K-Akt/PKB pathway may have therapeutic potential in the treatment of pancreatic duct tumors.

Adenocarcinoma↗
PubMed2005

Atorvastatin and myocardial reperfusion injury: new pleiotropic effect implicating multiple prosurvival signaling.

We investigated the potential role of atorvastatin, given at reperfusion, to improve survival of the ischemic/reperfused myocardium by activation of p44/42 MAPK and p38 MAPK with its downstream effector, HSP27. We have previously shown that atorvastatin attenuates lethal reperfusion-induced injury via activation of the phosphatidyl inositol 3-kinase (PI3K) prosurvival signaling pathway. In this study we hypothesize that other prosurvival kinases may also be implicated in this protection. Langendorff-perfused mouse hearts were subjected to 35 minutes of global ischemia followed by 30 minutes of reperfusion, and either infarct size or the levels of phosphorylated AKT, p44/42 MAPK, p38 MAPK, and HSP27 were analyzed. Atorvastatin was administered during reperfusion only. We used wortmannin to block PI3K/AKT, U0126 to block p44/42 MAPK, and SB203580 to prevent the phosphorylation of p38 MAPK and HSP27. Atorvastatin significantly reduced infarct size (32.96 +/- 3.4% versus 51.27 +/- 2.79% in controls, P < 0.05). This protection was abrogated by wortmannin (48.38 +/- 4.28%), U0126 (52.58 +/- 7.58), and SB203580 (49.37 +/- 4.16%). Western blot analysis confirmed significant phosphorylation of AKT, p44/42 MAPK, p38 MAPK, and HSP27 following administration of atorvastatin during reperfusion and abrogation of the respective phosphorylation in the presence of their specific inhibitors. Atorvastatin given at reperfusion attenuates lethal reperfusion-induced injury by the phosphorylation of multiple prosurvival pathways involving not only PI3K/AKT but also p44/42 MAPK, p38 MAPK, and HSP27.

Animals↗
PubMed2005

Deregulated matriptase causes ras-independent multistage carcinogenesis and promotes ras-mediated malignant transformation.

Overexpression of the type II transmembrane serine protease matriptase is a highly consistent feature of human epithelial tumors. Here we show that matriptase possesses a strong oncogenic potential when unopposed by its endogenous inhibitor, HAI-1. Modest orthotopic overexpression of matriptase in the skin of transgenic mice caused spontaneous squamous cell carcinoma and dramatically potentiated carcinogen-induced tumor formation. Matriptase-induced malignant conversion was preceded by progressive interfollicular hyperplasia, dysplasia, follicular transdifferentiation, fibrosis, and dermal inflammation. Furthermore, matriptase induced activation of the pro-tumorigenic PI3K-Akt signaling pathway. This activation was frequently accompanied by H-ras or K-ras mutations in carcinogen-induced tumors, whereas matriptase-induced spontaneous carcinoma formation occurred independently of ras activation. Increasing epidermal HAI-1 expression completely negated the oncogenic effects of matriptase. The data implicate dysregulated matriptase expression in malignant epithelial transformation.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2026

Integrated Multi-Omics Analysis Reveals the Genetic Basis of Phenotypic Variation in Tibetan Sheep.

Body size is a key economic trait influencing the profitability of farmed animals. This study used genome-wide association studies (GWAS) to identify five single nucleotide polymorphisms (SNPs) significantly associated with body size in the Tibetan sheep population, advancing molecular breeding and providing a basis for genomic selection. These SNPs are located within five candidate genes. SNaPshot validated GWAS results, demonstrating significant correlations between candidate SNPs and body size traits in Tibetan sheep. Concurrently, hematoxylin and eosin staining, alongside muscle fiber analysis, confirmed pronounced morphological differences in muscle tissue between sheep of varying conformation. Therefore, transcriptome and proteomics were performed on the longest dorsi muscle from large and small Tibetan sheep of both sexes. The transcriptome, together with weighted gene co-expression network analysis (WGCNA), identified VEPH1 and PRKG1 as core genes regulating body characteristics in Tibetan sheep through their involvement in the PI3K-Akt signaling pathway and pathways related to fat deposition. The integrative analyses demonstrated significantly different expression of CARNS1 and CRYAB at both transcriptional and protein levels between the muscles of large- and small-sized Tibetan sheep of both sexes, suggesting their importance in body size traits by influencing muscle morphology. This study provides valuable genomic resources that advance sheep genetics research.

GWAS↗