Somatic Gain of KRAS Function in the Endothelium is Sufficient to Cause Vascular Malformations that Require MEK but not PI3K Signaling
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ABSTRACT:
PROVIDER: PRJNA632020 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR11780513_1.fastq.gz | Fastqsanger.gz | |||
| SRR11780513_2.fastq.gz | Fastqsanger.gz | |||
| SRR11780514_1.fastq.gz | Fastqsanger.gz | |||
| SRR11780514_2.fastq.gz | Fastqsanger.gz | |||
| SRR11780515_1.fastq.gz | Fastqsanger.gz |
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Project description:Rationale – We previously identified somatic activating mutations in the KRAS gene in the endothelium of the majority of human sporadic brain arteriovenous malformations (bAVMs); a disorder characterized by direct connections between arteries and veins. However, whether this genetic abnormality alone is sufficient for lesion formation, as well as how active KRAS signaling contributes to AVM formation, remains unknown. Objective – To establish the first in vivo models of somatic KRAS gain of function in the endothelium in both mice and zebrafish in order to directly observe the phenotypic consequences of constitutive KRAS activity at a cellular level in vivo, and to test potential therapeutic interventions for AVMs. Methods and Results – Using both postnatal and adult mice, as well as embryonic zebrafish, we demonstrate that endothelial-specific gain of function mutations in Kras (G12D or G12V) are sufficient to induce bAVMs. Active KRAS signaling leads to altered endothelial cell morphogenesis and increased cell size, ectopic sprouting, expanded vessel lumen diameter, and direct connections between arteries and veins. Furthermore, we show that these lesions are not associated with altered endothelial growth dynamics or a lack of proper arteriovenous identity, but instead appear to feature exuberant angiogenic signaling. Finally, we demonstrate that KRAS-dependent AVMs in zebrafish are refractory to inhibition of the downstream effector PI3K, but instead require active MEK signaling. Conclusions – We demonstrate that active KRAS expression in the endothelium is sufficient for bAVM formation, even in the setting of uninjured adult vasculature. Furthermore, the finding that KRAS-dependent lesions are reversible in zebrafish suggests that MEK inhibition may represent a promising therapeutic treatment for AVM patients.
2020-07-01 | GSE150426 | GEO
Project description:RationaleWe previously identified somatic activating mutations in the KRAS (Kirsten rat sarcoma viral oncogene homologue) gene in the endothelium of the majority of human sporadic brain arteriovenous malformations; a disorder characterized by direct connections between arteries and veins. However, whether this genetic abnormality alone is sufficient for lesion formation, as well as how active KRAS signaling contributes to arteriovenous malformations, remains unknown.ObjectiveTo establish the first in vivo models of somatic KRAS gain of function in the endothelium in both mice and zebrafish to directly observe the phenotypic consequences of constitutive KRAS activity at a cellular level in vivo, and to test potential therapeutic interventions for arteriovenous malformations.Methods and resultsUsing both postnatal and adult mice, as well as embryonic zebrafish, we demonstrate that endothelial-specific gain of function mutations in Kras (G12D or G12V) are sufficient to induce brain arteriovenous malformations. Active KRAS signaling leads to altered endothelial cell morphogenesis and increased cell size, ectopic sprouting, expanded vessel lumen diameter, and direct connections between arteries and veins. Furthermore, we show that these lesions are not associated with altered endothelial growth dynamics or a lack of proper arteriovenous identity but instead seem to feature exuberant angiogenic signaling. Finally, we demonstrate that KRAS-dependent arteriovenous malformations in zebrafish are refractory to inhibition of the downstream effector PI3K but instead require active MEK (mitogen-activated protein kinase kinase 1) signaling.ConclusionsWe demonstrate that active KRAS expression in the endothelium is sufficient for brain arteriovenous malformations, even in the setting of uninjured adult vasculature. Furthermore, the finding that KRAS-dependent lesions are reversible in zebrafish suggests that MEK inhibition may represent a promising therapeutic treatment for arteriovenous malformation patients. Graphical Abstract: A graphical abstract is available for this article.
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Project description:Though mitogen activated protein kinase kinases (MKK or MEK) 1 and 2 are widely assumed to be functionally redundant some reports indicate they possess distinct biologic activities. To test the hypothesis that MEK1 and MEK2 signaling pathways are interchangeable we used two complementary approaches to determine the necessity and sufficiency of individual MEK1 and MEK2 signaling pathways for human melanoma SK-MEL-28 cell proliferation. To test the necessity we targeted MEK1 and/or MEK2 using specific siRNAs. An effect on proliferation was observed only when both MEK1 and MEK2 were knocked down indicating that neither of the individual MEK isoforms is necessary for SK-MEL-28 cell proliferation. To test the sufficiency we inhibited multiple MEK and MKK signaling pathways in SK-MEL-28 cells with anthrax lethal toxin (LeTx) a MEK/MKK-specific protease and rescued individual MEK signaling pathways by expressing a cleavage-resistant form of MEK (MEKcr). In this fashion ERK activation was retained only in MEK2cr-expressing cells but not in MEK1cr-expressing cells following LeTx treatment. Microarray analysis revealed groups of non-overlapping downstream transcriptional targets of MEK1 and MEK2 and indicated a substantial rescue effect of MEK2cr on proliferation pathways. Furthermore LeTx efficiently inhibited the cell proliferation and anchorage-independent growth of SK-MEL-28 cells expressing MKK1cr but not MEK2cr. These results not only indicate that in this cellular context MEK2 signaling pathway alone is sufficient for ERK activation melanoma cell proliferation and anchorage-independent growth but MEK1 is not but also demonstrate that MEK1 and MEK2 signaling pathways are not redundant and interchangeable for melanoma cell proliferation. We conclude that while MEK2 alone is sufficient for SK-MEL-28 cell proliferation MEK1 can conditionally compensate for loss of MEK2. SK-MEL-28 melanoma cells +/- cleavage resistant MKK1/MKK2
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Project description:Comparison of Tpl-2 small molecule inhibitor (SMI) versus MEK SMI activities in LPS-treated human monocytes will reveal a subset of genes that require Tpl-2 but are independent of MEK. Tpl-2 is a highly conserved (94% human versus mouse) serine-threonine kinase expressed in cells important to the inflammatory response, including monocytes, macrophages, dendritic cells, and B/T cells. The role of Tpl-2 in monocytes and macrophages has been especially well-studied. It has been shown in these cells that Tpl-2 is required for the expression of cytokines in response to Toll-like receptor ligands, including LPS. In resting cells, Tpl-2 forms a complex with p105 and ABIN-2. Upon stimulation, this complex dissociates. Dissociated p105 is processed to p50, which impacts transcription. Dissociated Tpl-2 phosphorylates MEK, which, in turn, phosphorylates ERK. ERK activates the transcription factor AP-1 and its downstream gene targets. An open question in the field is whether Tpl-2 acts solely through MEK to drive gene expression, or does Tpl-2 have any MEK-independent targets. Answering this question is important both for understanding basic Tpl-2 biology as well as its role in disease. Based on published data, Tpl-2 is important for inflammatory cytokine production, and in animal models where these cytokines contribute to disease (septic shock, IBD), blocking Tpl-2 ameliorates disease symptoms. We have a highly selective SMI of Tpl-2 that effectively blocks cytokine production in purified human monocytes. This SMI can block production of the same cytokines that a MEK inhibitor blocks, which is expected given that Tpl-2 lies upstream of MEK. However, the MEK SMI only partially inhibits certain cytokines, while the Tpl-2 SMI fully blocks them, suggesting there are additional factors downstream of Tpl-2 that are not MEK-dependent.
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Project description:Angiogenesis plays a key role in tumor metastasis. Many genes may act in this process including formation of vessels, immune evasion,etc. Different gene expression profiles between lymphoma endothelium cells and reactive lymph node-derived endothelium cells may uncover these genes. And intensive mechanism researches on such key genes may explain the mechanisim of tumor-specific angiogenesis and help to explore effective treatment strategies to prevent/reverse tumor metastasis. We use microarrays to detail gene expression profiles of human lymphoma endothelium and reactive lymph node-derived endothelium. Lymph nodes were taken from surgery samples of cases pathologically diagnosed DLBCL (diffuse large B-cell lymphoma), PTL (peripheral T cell lymphoma) and reactive lymph nodes. The pure endothelium cells were isolated by LCM after immunohistochemical staining of CD34. We found Tim-3 was preferentially expressed on lymphoma-derived ECs via different expression profiles between lymphoma ECs and reactive lymph node-derived ECs. Intensive researches were carried out on Tim-3-expressing -ECs and we found that Tim-3 -expressing-Ecs may play important role on EC-mediated tumor evasion.
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Project description:Angiogenesis plays a key role in tumor metastasis. Many genes may act in this process including formation of vessels, immune evasion,etc. Different gene expression profiles between lymphoma endothelium cells and reactive lymph node-derived endothelium cells may uncover these genes. And intensive mechanism researches on such key genes may explain the mechanisim of tumor-specific angiogenesis and help to explore effective treatment strategies to prevent/reverse tumor metastasis. We use microarrays to detail gene expression profiles of human lymphoma endothelium and reactive lymph node-derived endothelium.
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Project description:Though mitogen activated protein kinase kinases (MKK or MEK) 1 and 2 are widely assumed to be functionally redundant some reports indicate they possess distinct biologic activities. To test the hypothesis that MEK1 and MEK2 signaling pathways are interchangeable we used two complementary approaches to determine the necessity and sufficiency of individual MEK1 and MEK2 signaling pathways for human melanoma SK-MEL-28 cell proliferation. To test the necessity we targeted MEK1 and/or MEK2 using specific siRNAs. An effect on proliferation was observed only when both MEK1 and MEK2 were knocked down indicating that neither of the individual MEK isoforms is necessary for SK-MEL-28 cell proliferation. To test the sufficiency we inhibited multiple MEK and MKK signaling pathways in SK-MEL-28 cells with anthrax lethal toxin (LeTx) a MEK/MKK-specific protease and rescued individual MEK signaling pathways by expressing a cleavage-resistant form of MEK (MEKcr). In this fashion ERK activation was retained only in MEK2cr-expressing cells but not in MEK1cr-expressing cells following LeTx treatment. Microarray analysis revealed groups of non-overlapping downstream transcriptional targets of MEK1 and MEK2 and indicated a substantial rescue effect of MEK2cr on proliferation pathways. Furthermore LeTx efficiently inhibited the cell proliferation and anchorage-independent growth of SK-MEL-28 cells expressing MKK1cr but not MEK2cr. These results not only indicate that in this cellular context MEK2 signaling pathway alone is sufficient for ERK activation melanoma cell proliferation and anchorage-independent growth but MEK1 is not but also demonstrate that MEK1 and MEK2 signaling pathways are not redundant and interchangeable for melanoma cell proliferation. We conclude that while MEK2 alone is sufficient for SK-MEL-28 cell proliferation MEK1 can conditionally compensate for loss of MEK2.
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