Granzyme B ( GzmB ) promotes neutrophil infiltration , increased macrophage inflammatory protein-2 ( MIP-2 ) / IL-8 levels , and elevated elastase activity .

Further, granzyme B mediates IL-8 and macrophage inflammatory protein-2 secretion, lesional neutrophil infiltration, and lesional neutrophil elastase activity.

In our current study, GzmB stimulation increased IL-8 and MIP-2 secretion by pHEKs and primary mouse epidermal keratinocytes, respectively.

As GzmB induces COL17 loss in keratinocytes and keratinocyte secretion of IL-8 correlates to COL17 loss 38, GzmB may induce IL-8 secretion from keratinocytes in response to COL17 degradation.

To further test if GzmB positively regulated MIP-2 production and to ascertain keratinocytes as a cell source of MIP-2, MIP-2 was quantified in the supernatants of primary mouse epidermal keratinocytes after GzmB stimulation for 16h.

MIP-2 levels in the supernatant were increased in a GzmB-dose dependent manner while GzmB inhibitor VTI-1002 attenuated GzmB induced MIP-2 secretion.

Consistent with GzmB dependent elevation of neutrophil elastase activity in EBA, we identified GzmB dependent infiltration of neutrophils, a predominant source of neutrophil elastase 32, in EBA mice and GzmB dependent elevation of strong neutrophil chemoattractant MIP-2, a mouse homolog of human IL-8 33.

In our current study, GzmB stimulation increased IL-8 and MIP-2 secretion by pHEKs and primary mouse epidermal keratinocytes, respectively.

As GzmB did not directly degrade alpha6 integrin in pHEKs, we postulated that GzmB modulated alpha6 integrin loss in WT EBA mice by promoting neutrophil infiltration and neutrophil elastase activity.

Consistent with GzmB dependent elevation of neutrophil elastase activity in EBA, we identified GzmB dependent infiltration of neutrophils, a predominant source of neutrophil elastase 32, in EBA mice and GzmB dependent elevation of strong neutrophil chemoattractant MIP-2, a mouse homolog of human IL-8 33.

Further, granzyme B mediates IL-8 and macrophage inflammatory protein-2 secretion, lesional neutrophil infiltration, and lesional neutrophil elastase activity.

Indeed , a recent work revealed that GzmB activates caspase 3 in secretory lysosomes of mast cells , a mechanism which possibly contributes to enhanced caspase 3-dependent proteolytic cleavage in the extracellular space39 .

Indeed, a recent work revealed that GzmB activates caspase 3 in secretory lysosomes of mast cells, a mechanism which possibly contributes to enhanced caspase 3 dependent proteolytic cleavage in the extracellular space 39.

Indeed, a recent work revealed that GzmB activates caspase 3 in secretory lysosomes of mast cells, a mechanism which possibly contributes to enhanced caspase 3-dependent proteolytic cleavage in the extracellular space xref .

As proteolytic degradation of alpha6 integrin by other proteases has been reported 31, we hypothesized that GzmB augments inflammation to increase the activity of other proteases to degrade alpha6 integrin.

As proteolytic degradation of alpha6 integrin by other proteases has been reported31 , we hypothesized that GzmB augments inflammation to increase the activity of other proteases to degrade alpha6 integrin .

In this traditional dogma , GzmB was considered to be exclusively released from the granules of cytotoxic T and natural killer cells and internalized into target cells through perforin-mediated pores to initiate apoptosis .

Further, granzyme B mediates IL-8 and macrophage inflammatory protein-2 secretion, lesional neutrophil infiltration, and lesional neutrophil elastase activity.

As GzmB did not directly degrade alpha6 integrin in pHEKs, we postulated that GzmB modulated alpha6 integrin loss in WT EBA mice by promoting neutrophil infiltration and neutrophil elastase activity.

Therefore, simultaneous induction of nitric oxide, respiratory burst and tryptophan degradation responses would antagonize PKC and thus NADPH oxidase activation and the IDO enzyme.

Previous studies have suggested nitric oxide (NO) can inhibit IDO activity and expression [XREF_BIBR, XREF_BIBR] most likely through post-translational regulation leading to proteasomal degradation of IDO rather than transcriptional regulation [XREF_BIBR].

Previous studies have suggested nitric oxide (NO) can inhibit IDO activity and expression [XREF_BIBR, XREF_BIBR] most likely through post-translational regulation leading to proteasomal degradation of IDO rather than transcriptional regulation [XREF_BIBR].

Several findings have demonstrated that NO is able to inhibit the IDO enzyme by direct interaction or accelerating proteasomal degradation [XREF_BIBR, XREF_BIBR].

Although not yet examined in the context of exercise, nitric oxide has been shown to inhibit IDO activity.

33 Thus, a strong rationale suggests that exercise induced changes in nitric oxide may mediate an inhibition of IDO activity, possibly leading to a chronic downregulation and stabilization of the KYN pathway as reported by Zimmer et al. 23 The mechanisms underlying both acute and chronic exercise induced elevations in the metabolic flux towards KA could be driven by KAT expression in different tissues or cell types.

Cells expressing IDO can co-express iNOS in response to IFN-gamma, which produces NO that inhibits, in turn, IDO.

Previous studies have reported that NO is able to inhibit the activity of IDO by reacting with the heme iron situated in its active site.

NO inhibits IDO at the transcriptional level and accelerates the decomposition of IDO protein, thereby affecting its stability.

For example, nitric oxide (NO) production may block IDO enzyme activity since NO inhibits the activity of heme containing enzymes such as IDO (Thomas et al., 2001).

For example, nitric oxide (NO) production may block IDO enzyme activity since NO inhibits the activity of heme containing enzymes such as IDO (Thomas et al., 2001).

In sharp contrast to macrophages, murine microglial cell clones immortalized with the activated c-myc oncogene have been reported to be resistant to NO inhibition of IDO.

In conclusion, results of the present series of experiments indicate that IDO in primary murine microglia costimulated with IFNgamma + LPS is not impaired by the production of NO, as is known to occur in murine macrophages.

Conversely, induction of NO by activation of iNOS down-regulates IDO activity in cell types as diverse as human uroepithelial transformed cells, murine bone marrow derived myeloid dendritic cells, human transformed and primary macrophages and mouse peritoneal cells.

As a result of this crosstalk, NO is well known to inhibit IDO activity in many types of cells.

In addition, direct binding of NO to heme iron in IDO, which is one of the mechanisms by which NO inhibits IDO at the post-translational level, is dependent on a number of cellular factors, including NO abundance, pH, redox environment and tryptophan availability.

NO inhibition of IDO is apparently specific to both certain species and cell types.

In macrophages, the inhibition of IDO by NO occurs at both the transcriptional and post-transcriptional levels.

The loss of AR increased NGF expression in our study , suggesting that the AR may act as an upstream regulator that downregulates the NGF in the absence of ADT .

Repression of AR signaling increases the NGF and is associated with NEPC differentiation.

We found that CSS treated cells had increased levels of the NGF and were associated with higher neuroendocrine marker expressions compared to cells cultured in fetal bovine serum (FBS)-containing medium; however, AR ligand (dihydrotestosterone (DHT))-treated cells had reduced levels of NGF and neuroendocrine markers.

AR inhibition by CSS or enzalutamide upregulates the NGF possibly because ADT inhibits the AR.

The AR may act upstream of both ZBTB46 and the NGF, and downregulates ZBTB46 and the NGF before ADT.

These findings suggest a mechanism whereby ADT upregulated ZBTB46 enhances NGF transcription through direct physical interaction with the NGF-regulatory sequence.

We hypothesized that ZBTB46 upregulates NGF expression in prostate cancer cells by acting as a transcriptional activator and binding to a ZBTB46 binding element (ZBE) in the NGF regulatory sequence.

Moreover, ZBTB46 binding signals were enriched in C4-2 and LNCaP cells in response to CSS containing medium or MDV3100, supporting the hypothesis that ADT increased ZBTB46 upregulates NGF expression.

These findings suggest a mechanism whereby ADT upregulated ZBTB46 enhances NGF transcription through direct physical interaction with the NGF-regulatory sequence.

We further knocked-down AR in AR positive LNCaP cells using AR small interfering RNA, and found that knockdown of AR increased ZBTB46 and NGF expressions.

This suggests that NTRK1 and the NGFR might not respond to AR signaling, and the roles of NGF–NGFR or NGF–NTRK1 signaling pathways might differ from that of NGF–CHRM4 signaling in prostate cancer.

This suggests that NTRK1 and the NGFR might not respond to AR signaling, and the roles of NGF–NGFR or NGF–NTRK1 signaling pathways might differ from that of NGF–CHRM4 signaling in prostate cancer.

They show that NGF interacts with the GPCR CHRM4, that both NGF and CHRM4 are upregulated in highly metastatic prostate cancer and that targeting NGF reduces therapy resistance in a mouse xenograft model.

The results suggest an approach for NEPC treatment by targeting NGF–CHRM4 signaling.

Since the activated PI3K/AKT pathway was reported to cross-talk with stimulated muscarinic receptor signaling xref , xref , and activated AKT is associated with MYCN expression in contributing to NEPC transformation xref , we hypothesized that stimulation of the NGF–CHRM4 axis might upregulate AKT-MYCN signaling in prostate cancer.

Since we showed that upregulated NGF cannot increase expression of CHRM1 and CHRM3 (Fig.  xref ; Supplementary Fig.  xref ), this result suggests that NGF–CHRM4 might be a unique signaling pathway involved in neuroendocrine differentiation of prostate cancer that differs from canonical acetylcholine–CHRM pathways.

NGF is associated with CHRM4 and was shown to be upregulated in high-grade and SCNC samples.

IHC analyses revealed that cytoplasmic NGF was associated with increased cytoplasmic CHRM4 and was highly expressed in high-grade tumors and SCNC samples (Fig.  xref ).

These results support that activation of NGF–CHRM4 signaling is connected to malignant progression and neuroendocrine differentiation of prostate cancer.

NGF physically interacts with CHRM4 after ADT.

To determine the possible interaction between NGF and CHRM4, AR-positive cells were subjected to ADT followed by an immunoprecipitation (IP)-Western blot analysis.

These observations confirm that the NGF physically interacts with CHRM4.

Our study demonstrated that inhibition of AR signaling decreases activation of the NGF–CHRM4 axis, which is associated with neuroendocrine differentiation of prostate cancer, suggesting that current hormonal therapy designed to suppress AR functions may predispose prostate cancer to NEPC development.

We demonstrated that the NGF physically interacts with CHRM4 and that the NGF mediates NEPC differentiation dependent on CHRM4.

This suggests that NTRK1 and the NGFR might not respond to AR signaling, and the roles of NGF–NGFR or NGF–NTRK1 signaling pathways might differ from that of NGF–CHRM4 signaling in prostate cancer.

The specificity of the NGF–CHRM4 interrelationship can be used to develop specific drugs that target this interaction.

Thus, our findings offer the potential to develop a prognostic information for current AR-directed therapeutic strategies with an antagonist of NGF–CHRM4 signaling.

NGF physically interacts with CHRM4 after ADT.

To determine the possible interaction between NGF and CHRM4, AR positive cells were subjected to ADT followed by an immunoprecipitation (IP)-Western blot analysis.

These observations confirm that the NGF physically interacts with CHRM4.

We demonstrated that the NGF physically interacts with CHRM4 and that the NGF mediates NEPC differentiation dependent on CHRM4.

The NGF was reported to promote prostate cancer cell metastasis XREF_BIBR, XREF_BIBR, yet the mechanisms and functions of NGF in NEPC differentiation have not been clearly elucidated.

In prostate cancer, the NGF stimulates NTRK1 downstream of p38-MAPK activation to promote cell migration, invasion, and metastasis 11.

In prostate cancer, the NGF stimulates NTRK1 downstream of p38-MAPK activation to promote cell migration, invasion, and metastasis 11.

In prostate cancer, the NGF stimulates NTRK1 downstream of p38-MAPK activation to promote cell migration, invasion, and metastasis 11.

Pharmacologic NGF blockade and NGF knockdown markedly inhibited CHRM4 mediated NEPC differentiation and AKT-MYCN signaling activation.

These results are consistent with the notion that the NGF upregulates CHRM4, through which it activates AKT-MYCN signaling after ADT.

Taken together, our findings support a model wherein ADT or AR inhibitor treatment stimulates ZBTB46 expression, which upregulates NGF mediated CHRM4 stimulation; this plays a pivotal role in integrating AKT and MYCN signals to promote therapeutic resistance and neuroendocrine differentiation of prostate cancer.

Activated NGF upregulates CHRM4 and links AKT signaling activation and MYCN stimulation to enhance NEPC reprogramming.

In prostate cancer, the NGF stimulates NTRK1 downstream of p38-MAPK activation to promote cell migration, invasion, and metastasis 11.

Indeed, involvement of the NGF in pancreatic cancer was demonstrated to increase cell proliferation and survival through activation of mitogen activated protein kinase (MAPK) via the NTRK1 receptor 8.

Notably, overexpression of the NGF in cells promoted cell proliferation regardless of CSS containing medium treatment, whereas NGF-knockdown in AR negative PC3 and ADT-resistance C4-2-MDVR cells reduced cell proliferation and colony formation compared to cells carrying the control vector.

In prostate cancer, the NGF stimulates NTRK1 downstream of p38-MAPK activation to promote cell migration, invasion, and metastasis 11.

Indeed, it is clear that many types of tumors have the potential to secrete NGF, which induces peripheral nerve infiltration into the tumor microenvironment, thereby promoting tumor growth and metastasis XREF_BIBR, XREF_BIBR.

In addition, the NGF stimulates nerve infiltration into solid tumors and acts as a mediator of pain through activation of NTRK1 in the endings of sensory neurons 65.

ZBTB46 directly binds to the regulatory sequence of the NGF and upregulates NGF expression We hypothesized that ZBTB46 upregulates NGF expression in prostate cancer cells by acting as a transcriptional activator and binding to a ZBTB46-binding element ( ZBE ) in the NGF regulatory sequence .

Moreover , ZBTB46-binding signals were enriched in C4-2 and LNCaP cells in response to CSS-containing medium or MDV3100 ( Fig. 2e , f ) , supporting the hypothesis that ADT-increased ZBTB46 upregulates NGF expression .

Here, we show that an androgen deprivation therapy (ADT)-stimulated transcription factor, ZBTB46, upregulated NGF via ZBTB46 mediated-transcriptional activation of NGF.

ZBTB46 upregulated NGF is associated with NEPC differentiation.

These results indicate that ADT increased NGF promotes NEPC differentiation and suggest that NGF expression is likely regulated by ZBTB46.

Nerve growth factor interacts with CHRM4 and promotes neuroendocrine differentiation of prostate cancer and castration resistance.

Our study provides evidence that the NGF-CHRM4 axis has potential to be considered as a therapeutic target to impair NEPC progression.

Pharmacologic NGF blockade and NGF knockdown markedly inhibited CHRM4 mediated NEPC differentiation and AKT-MYCN signaling activation.

Here, we show that an androgen deprivation therapy (ADT)-stimulated transcription factor, ZBTB46, upregulated NGF via ZBTB46 mediated-transcriptional activation of NGF.

Here, we show that an androgen deprivation therapy (ADT)-stimulated transcription factor, ZBTB46, upregulated NGF via ZBTB46 mediated-transcriptional activation of NGF.

A low LCR was identified in 21 patients and was significantly correlated with older age, a high CRP-albumin ratio, and advanced disease stage, and was a prognostic factor for OS and DFS.

The kinase activity of TAK1 leads to phosphorylation events that activate AP-1 and NF-κB. In parallel to cIAP-induced ubiquitination of RIPK2, XIAP’s enzymatic activity results in the formation of polyubiquitin chains on RIPK2, serving as a platform to engage another E3 ligase complex known as the Linear Ubiquitin Assembly Complex (LUBAC) ( xref , xref ).

K63-linked ubiquitination of RIPK2 has been established as a means to construct protein scaffolds that transduce downstream signaling.

In a step-wise fashion, ubiquitination of RIPK2 leads to activation and recruitment of the TAK1 complex, consisting of TAK1 in association with TAK1-binding protein (TAB)2 and 3.

It was recently shown that MAVS recruits NLRP3 to the mitochondria for activation in response to non crystalline activators and that microtubule driven trafficking of the mitochondria is necessary for NLRP3 and ASC complex assembly and activation.

It was recently shown that MAVS recruits NLRP3 to the mitochondria for activation in response to non crystalline activators and that microtubule driven trafficking of the mitochondria is necessary for NLRP3 and ASC complex assembly and activation.

By triggering the phosphorylation of the autophagy inducer ULK1, RIPK2 induces autophagy of disrupted mitochondria (mitophagy), preventing the accumulation of ROS and NLRP3 inflammasome activation.

Conversely, others have shown that overexpression of NLRP7 inhibited pro-IL-1beta synthesis and secretion.

Some studies have suggested that NLRP12 may negatively regulate the NF-kappaB pathway.

IFNgamma functions via signal transducer and activator of transcription 1 (STAT1) and can not induce NLRC5 expression in the absence of STAT1.

Despite this focus, much of the nature of the NOD1 and 2 interaction with these structures remains unknown, although recent findings suggest that NOD2 directly binds MDP with high affinity ( xref ), with the N-glycosylated form specific to the mycobacterial cell wall triggering an exceptionally strong immunogenic response compared to N-acetyl MDP ( xref ).

Moreover, it was recently reported that bacterial acylated lipopeptides (acLP) activated NLRP7 and stimulated formation of an NLRP7-ASC-caspase-1 inflammasome ( xref ).

It was recently shown that MAVS recruits NLRP3 to the mitochondria for activation in response to non crystalline activators and that microtubule driven trafficking of the mitochondria is necessary for NLRP3 and ASC complex assembly and activation.

While this mechanism is still poorly understood, the ability of NLRP10 to interact with NOD1 as well as its signaling targets RIPK2, TAK1, and NEMO, suggests that NLRP10 may be involved in optimizing cytokine release following bacterial infections.

NOD1 and 2 both interact with RIPK2, via a CARD-CARD homotypic interaction.

In Alzheimer 's disease, amyloid-beta aggregates were shown to activate NLRP3 ex vivo in primary macrophages and microglia.

The possibility of a role for NOD2 in non bacterial infections has also been suggested, with NOD2 having been shown to induce an IFNbeta driven antiviral response following recognition of single stranded viral RNA.

IL-1beta produced downstream of the NLRP3 inflammasome, which is also stimulated by islet amyloid polypeptide, promotes beta-cell dysfunction, and cell death, linking NLRP3 activation to insulin resistance.

Moreover, it was recently reported that bacterial acylated lipopeptides (acLP) activated NLRP7 and stimulated formation of an NLRP7-ASC-caspase-1 inflammasome.

NLRX1 has been shown to enhance ROS production when it is overexpressed, following Chlamydia and Shigella infection, as well as in response to TNFalpha and poly (I : C).

A recent study by Zhong et al. suggested that particulate stimuli might induce mitochondrial production of reactive oxygen species (ROS), which triggers a calcium influx mediated by transient receptor potential melastatin 2 (TRPM2) to activate NLRP3.

A recent study by Zhong et al. suggested that particulate stimuli might induce mitochondrial production of reactive oxygen species (ROS), which triggers a calcium influx mediated by transient receptor potential melastatin 2 (TRPM2) to activate NLRP3.

Ceballos-Olvera et al. demonstrated that while IL-18 and pyroptosis are both essential for host resistance, the production of IL-1beta by NLRP3 was deleterious, as it triggered excessive neutrophil recruitment and exacerbated the disease.

Mutations in NLRP3 were reported to induce an overproduction of IL-1beta that triggers the subsequent development of severe inflammation.

Other NLRs such as NOD1, NOD2, NLRP10, NLRX1, NLRC5, and CIITA do not directly engage the inflammatory caspases, but instead activate nuclear factor-kappaB (NF-kappaB), mitogen activated protein kinases (MAPKs), and interferon (IFN) regulatory factors (IRFs) to stimulate innate immunity.

A recent study by Zhong et al. suggested that particulate stimuli might induce mitochondrial production of reactive oxygen species (ROS), which triggers a calcium influx mediated by transient receptor potential melastatin 2 (TRPM2) to activate NLRP3.

By triggering the phosphorylation of the autophagy inducer ULK1, RIPK2 induces autophagy of disrupted mitochondria (mitophagy), preventing the accumulation of ROS and NLRP3 inflammasome activation.

Nlrp6 - / - mice had increased numbers of immune cells in their circulation, as well as enhanced activation of MAPK and NF-kappaB signaling, though Toll like receptor (TLR) activation, suggesting that NLRP6 may suppress TLR pathways after the recognition of pathogens to prevent amplified inflammatory pathology.

Other NLRs such as NOD1, NOD2, NLRP10, NLRX1, NLRC5, and CIITA do not directly engage the inflammatory caspases, but instead activate nuclear factor-kappaB (NF-kappaB), mitogen activated protein kinases (MAPKs), and interferon (IFN) regulatory factors (IRFs) to stimulate innate immunity.

Few ligands have been found for NLRP1 to date, and include bacterial products such as lethal toxin (LT) produced by Bacillus anthracis which activates murine NLRP1b ( xref ), muramyl dipeptide (MDP), a component of bacterial peptidoglycan that activates human NLRP1; and reduced levels of cytosolic ATP ( xref – xref ).

Moreover, it was recently reported that bacterial acylated lipopeptides (acLP) activated NLRP7 and stimulated formation of an NLRP7-ASC-caspase-1 inflammasome ( xref ).

The exact mechanism of NLRP3 activation by uric acid crystals is still unknown, but monosodium urate and calcium pyrophosphate dihydrate crystals were found to induce NLRP3 and caspase-1 activation and the subsequent processing of IL-1beta and IL-18.

The exact mechanism of NLRP3 activation by uric acid crystals is still unknown, but monosodium urate and calcium pyrophosphate dihydrate crystals were found to induce NLRP3 and caspase-1 activation and the subsequent processing of IL-1beta and IL-18.

The exact mechanism of NLRP3 activation by uric acid crystals is still unknown, but monosodium urate and calcium pyrophosphate dihydrate crystals were found to induce NLRP3 and caspase-1 activation and the subsequent processing of IL-1beta and IL-18.

The exact mechanism of NLRP3 activation by uric acid crystals is still unknown, but monosodium urate and calcium pyrophosphate dihydrate crystals were found to induce NLRP3 and caspase-1 activation and the subsequent processing of IL-1beta and IL-18.

A recent study by Zhong et al. suggested that particulate stimuli might induce mitochondrial production of reactive oxygen species (ROS), which triggers a calcium influx mediated by transient receptor potential melastatin 2 (TRPM2) to activate NLRP3.

The exact mechanism of NLRP3 activation by uric acid crystals is still unknown, but monosodium urate and calcium pyrophosphate dihydrate crystals were found to induce NLRP3 and caspase-1 activation and the subsequent processing of IL-1beta and IL-18.

The exact mechanism of NLRP3 activation by uric acid crystals is still unknown, but monosodium urate and calcium pyrophosphate dihydrate crystals were found to induce NLRP3 and caspase-1 activation and the subsequent processing of IL-1beta and IL-18.

The exact mechanism of NLRP3 activation by uric acid crystals is still unknown, but monosodium urate and calcium pyrophosphate dihydrate crystals were found to induce NLRP3 and caspase-1 activation and the subsequent processing of IL-1beta and IL-18.

The exact mechanism of NLRP3 activation by uric acid crystals is still unknown, but monosodium urate and calcium pyrophosphate dihydrate crystals were found to induce NLRP3 and caspase-1 activation and the subsequent processing of IL-1beta and IL-18.

Ceramide, a specific product from the metabolism of long-chain saturated fatty acids, and the saturated free fatty acid, palmitate, have been shown to induce IL-1beta in an NLRP3 dependent fashion [Ref.

Crystalline cholesterol was proposed to cause atherosclerosis by acting as a danger signal and initiating inflammation through the NLRP3 inflammasome.

A recent study by Zhong et al. suggested that particulate stimuli might induce mitochondrial production of reactive oxygen species (ROS), which triggers a calcium influx mediated by transient receptor potential melastatin 2 (TRPM2) to activate NLRP3.

The data suggest that in hepatocytes merlin is functionally linked to the hippo pathway and acts upstream Mst1/2 by recruiting LATS to the membrane comparable to what has been shown in FH912 Schwann cell line.

Translocation of merlin to the nucleus allows merlin to bind and inhibit the E3 ubiquitin ligase CRL4 DCAF1 ( D DB1- and C ul4- A ssociated F actor 1) ( xref , xref ).

Translocation of merlin to the nucleus allows merlin to bind and inhibit the E3 ubiquitin ligase CRL4 DCAF1 (DDB1- and Cul4 Associated Factor 1).

For example, in confluent human umbilical vein endothelial cells, merlin suppressed recruitment of Rac to the plasma membrane, and its silencing promoted recruitment of Rac1 to sites of extracellular matrix adhesion, and promoted cell growth ( xref ).

Previously, we showed that activation of ErbB2/ErbB3 receptors in primary rat Schwann cells by neuregulin-1 induced merlin phosphorylation at Ser518 via PKA ( xref ).

Notably, NF2 transfection into these cells induced YAP1 phosphorylation at Ser127, YAP1 retention in the cytoplasm and consequent reduction of YAP1 nuclear localization.

Previously, we showed that activation of ErbB2 and ErbB3 receptors in primary rat Schwann cells by neuregulin-1 induced merlin phosphorylation at Ser518 via PKA.

Previously, we showed that activation of ErbB2 and ErbB3 receptors in primary rat Schwann cells by neuregulin-1 induced merlin phosphorylation at Ser518 via PKA.

Previously, we showed that activation of ErbB2 and ErbB3 receptors in primary rat Schwann cells by neuregulin-1 induced merlin phosphorylation at Ser518 via PKA.

We reported that merlin associates with beta 1 -integrin in primary Schwann cells and undifferentiated Schwann cell and neuron co-cultures, and in primary Schwann cell cultures, laminin-1 stimulated integrin signaled though PAK1 and caused merlin Ser518 phosphorylation and inactivation of its tumor suppressor function.

Merlin is phosphorylated at Ser10, Thr230 and Ser315 by Akt (also known as protein kinase B, PKB) and controls merlin’s proteasome-mediated degradation by ubiquitination to prevent its interaction with binding partners ( xref , xref ).

Merlin is phosphorylated at Ser10, Thr230 and Ser315 by Akt (also known as protein kinase B, PKB) and controls merlin 's proteasome mediated degradation by ubiquitination to prevent its interaction with binding partners.

Merlin is phosphorylated at Ser10, Thr230 and Ser315 by Akt (also known as protein kinase B, PKB) and controls merlin 's proteasome mediated degradation by ubiquitination to prevent its interaction with binding partners.

Merlin is phosphorylated at Ser10, Thr230 and Ser315 by Akt (also known as protein kinase B, PKB) and controls merlin’s proteasome-mediated degradation by ubiquitination to prevent its interaction with binding partners ( xref , xref ).

Merlin is phosphorylated at Ser10, Thr230 and Ser315 by Akt (also known as protein kinase B, PKB) and controls merlin’s proteasome-mediated degradation by ubiquitination to prevent its interaction with binding partners ( xref , xref ).

Merlin is phosphorylated at Ser10, Thr230 and Ser315 by Akt (also known as protein kinase B, PKB) and controls merlin 's proteasome mediated degradation by ubiquitination to prevent its interaction with binding partners.

Loss of merlin results in integrin mediated activation of mTORC1 through PAK1, which promotes cell cycle progression by inducing translation of cyclin-D1 mRNA and cyclin-D1 expression.

Loss of merlin in mesotheliomas has been linked not only to increased proliferation, but also increased invasiveness, spreading and migration.

Adenoviral transduction of NF2 in Meso-17 and Meso-25 cell lines decreased invasion through Matrigel membranes compared to cells transduced with empty vector.

Second, similar to NF2 schwannomas, mesothelioma cells with NF2 inactivation, exhibit activated PAK1 and AKT, and re-expression of merlin in merlin-null human mesothelioma cells (Meso-17) decreases PAK1 activity.

Soon after merlin was cloned, evidence that merlin inhibits another important member of the Rho GTPases family, Ras, was reported in v-Ha-Ras-transformed NIH3T3cells in which merlin overexpression counteracted the oncogenic role of Ras.

Merlin re-expression in Nf2 -/- Schwann cells similarly reduced the transport of growth factor receptors ErbB2 and ErbB3, insulin like growth factor 1 receptor (IGF1R) and platelet derived growth factor receptor (PDGFR).

Merlin re-expression in Nf2 -/- Schwann cells similarly reduced the transport of growth factor receptors ErbB2 and ErbB3, insulin like growth factor 1 receptor (IGF1R) and platelet derived growth factor receptor (PDGFR).

In sum, multiple lines of evidence have established a feedback regulation loop with merlin being phosphorylated at Ser518 (growth permissive form) via activated Rho small GTPases Rac1 and Cdc42 through PAK, and in turn, merlin associating with PAK to inhibit Rac1 and Cdc42 signaling (XREF_FIG).

Collectively, these results indicate that merlin inhibits cell growth by contact inhibition in part by binding CD44 and negatively regulating CD44 function (XREF_FIG).

Merlin inactivation of Src signaling was also shown in CNS glial cells, where merlin competitively inhibits Src binding to ErbB2 thereby preventing ErbB2 mediated Src phosphorylation and downstream mitogenic signaling.

In the NF2 -/- breast cancer MDA-MB-231 cell line, merlin re-expression inhibited YAP and TEAD activity that was eliminated by LATS1/2 silencing.

Loss of merlin results in integrin mediated activation of mTORC1 through PAK1, which promotes cell cycle progression by inducing translation of cyclin-D1 mRNA and cyclin-D1 expression.

Loss of merlin activated mTORC1 signaling independently of Akt or ERK in these tumor cells; however, the molecular mechanism connecting merlin loss to mTORC1 activation remains to be elucidated.

Loss of merlin activated mTORC1 signaling independently of Akt or ERK in these tumor cells; however, the molecular mechanism connecting merlin loss to mTORC1 activation remains to be elucidated.

Furthermore, merlin overexpression in Tr6BC1 mouse schwannoma cells inhibited the binding of fluorescein labeled hyaluronan to CD44 and inhibited subcutaneous tumor growth in immunocompromised mice, and overexpression of a merlin mutant lacking the CD44 binding domain was unable to inhibit schwannoma growth.

Further studies showed that wild-type merlin is transported throughout the cell by microtubule motors and merlin mutants or depletion of the microtubule motor kinesin-1 suppressed merlin transport and was associated with accumulation of yorkie, a Drosophila homolog of the hippo pathway transcriptional co-activator Yes associated protein (YAP), in the nucleus.

In a similar fashion, NF2 mutations increased the resistance to dihydrofolate reductase inhibitors methotrexalate and pyremethamine as well as the JNK inhibitor JNK-9L.

The disrupted cell-contact inhibition signaling and merlin phosphorylation correlated with increased expression of NOTCH1 and its downstream target gene, HES1, which represses the transcription factor E2F in cell-contact growth arrest.

Binding of merlin unphosphorylated at Ser518 with the cytoplasmic tail of CD44 mediates contact inhibition at high cell density.

Loss of merlin activated mTORC1 signaling independently of Akt or ERK in these tumor cells; however, the molecular mechanism connecting merlin loss to mTORC1 activation remains to be elucidated.

First, protein kinase C potentiated phosphatase inhibitor (CPI-17), which is frequently overexpressed in mesothelioma tumors, inhibits merlin phosphatase MYPT1-PP1delta, providing one potential pathway by which merlin 's tumor suppressor function might be inactivated through maintenance of phosphorylation at Ser518.

First, protein kinase C potentiated phosphatase inhibitor (CPI-17), which is frequently overexpressed in mesothelioma tumors, inhibits merlin phosphatase MYPT1-PP1delta, providing one potential pathway by which merlin 's tumor suppressor function might be inactivated through maintenance of phosphorylation at Ser518.

Loss of merlin results in integrin mediated activation of mTORC1 through PAK1, which promotes cell cycle progression by inducing translation of cyclin-D1 mRNA and cyclin-D1 expression.

HDAC inhibitors disrupt the PP1-HDAC interaction facilitating Akt dephosphorylation and decrease human meningioma and schwannoma cell proliferation and schwannoma growth in an allograft model and meningioma growth in an intracranial xenograft model.

The mTORC1 inhibitor rapamycin selectively inhibited proliferation of seven merlin-null mesothelioma cell lines, but not merlin positive cell lines, suggesting a potential pharmacological target for merlin deficient mesotheliomas.

Merlin expression in Meso-17 and Meso-25 cells decreased FAK Tyr397 phosphorylation and consequently disrupted FAK-Src and PI3K interaction, providing a mechanism for the observed enhancement of invasion and spreading caused by merlin inactivation.

Accordingly, merlin was shown to reduce the levels of ErbB2 and ErbB3 receptor levels at the plasma membrane.

Accordingly, merlin was shown to reduce the levels of ErbB2 and ErbB3 receptor levels at the plasma membrane.

Accordingly, merlin was shown to reduce the levels of ErbB2 and ErbB3 receptor levels at the plasma membrane.

In sub-confluent primary Schwann cells, we found that merlin binds to paxillin and mediates merlin localization at the plasma membrane and association with beta1-integrin and ErbB2, modifying the organization of the actin cytoskeleton in a cell density dependent manner.

In sub-confluent primary Schwann cells, we found that merlin binds to paxillin and mediates merlin localization at the plasma membrane and association with β1-integrin and ErbB2, modifying the organization of the actin cytoskeleton in a cell density-dependent manner ( xref ).

Moreover, in cultured Schwann cells, merlin interaction with Amot was demonstrated by co-immunoprecipitation of the endogenous proteins.

Moreover, in cultured Schwann cells, merlin interaction with Amot was demonstrated by co-immunoprecipitation of the endogenous proteins ( xref ).

Merlin-Amot interaction was required for merlin regulation of mitogenic MAPK signaling.

Moreover, co-immunoprecipitation experiments revealed that merlin interacts with YAP1, although the interaction is not direct.

Moreover, co-immunoprecipitation experiments revealed that merlin interacts with YAP1, although the interaction is not direct ( xref ).

Studies in human meningioma tumors and in paired cell lines—KY21MG1 or MENII-1 meningioma cell lines and AC1 arachnoidal cells—demonstrated that merlin loss was associated with increased YAP expression and nuclear localization.

Amot-p130 isoform bound to the WW domains of YAP and blocked LATS1 access to YAP.

The activation of Rac1 through CD44 was identified via the interaction of CD44 with Tiam-1, a Rac1 guanine nucleotide exchange factor (GEF) that catalyzes the replacement of the tightly-bound GDP with GTP.

Merlin inactivation of Src signaling was also shown in CNS glial cells, where merlin competitively inhibits Src binding to ErbB2 thereby preventing ErbB2-mediated Src phosphorylation and downstream mitogenic signaling.

Merlin inactivation of Src signaling was also shown in CNS glial cells, where merlin competitively inhibits Src binding to ErbB2 thereby preventing ErbB2 mediated Src phosphorylation and downstream mitogenic signaling.

Merlin interacts with tubulin and acetylated-tubulin and stabilizes the microtubules by attenuating tubulin turnover -- lowering the rates of microtubule polymerization and depolymerization.

Merlin interacts with tubulin and acetylated-tubulin and stabilizes the microtubules by attenuating tubulin turnover—lowering the rates of microtubule polymerization and depolymerization.

Merlin inhibits PI3K activity by binding phosphatidylinositol 3-kinase enhancer-L (PIKE-L), the GTPase that binds and activates PI3K.

HDAC inhibitors disrupt the PP1-HDAC interaction facilitating Akt dephosphorylation and decrease human meningioma and schwannoma cell proliferation and schwannoma growth in an allograft model and meningioma growth in an intracranial xenograft model ( xref , xref , xref ).

Hyaluronan-CD44 interaction in astrocytes and an immortalized mouse mammary epithelial cell line, EpH4, leads to Rac1 signaling activation and actin cytoskeleton rearrangement ( xref , xref ).

In various cell types, the binding of hyaluronan to CD44 stimulates Tiam1 dependent Rac1 signaling and cytoskeleton mediated tumor cell migration.

In various cell types, the binding of hyaluronan to CD44 stimulates Tiam1 dependent Rac1 signaling and cytoskeleton mediated tumor cell migration.

Pharmacological or genetic inhibition of Rac1 in Nf2 -/- MEFs reduced the Wnt signaling activation to basal levels as assessed by reporter assay of transactivation of the nuclear beta-catenin-dependent T-cell factor 4 transcription factor.