Group IVA Cytosolic Phospholipase A2Regulates the G2-to-M Transition by Modulating the Activity of Tumor Suppressor SIRT2

The G2-to-M transition (or prophase) checkpoint of the cell cycle is a critical regulator of mitotic entry. SIRT2, a tumor suppressor gene, contributes to the control of this checkpoint by blocking mitotic entry under cellular stress. However, the mechanism underlying both SIRT2 activation and regulation of the G2-to-M transition remains largely unknown. Here, we report the formation of a multiprotein complex at the G2-to-M transitionin vitroandin vivo. Group IVA cytosolic phospholipase A2(cPLA2α) acts as a bridge in this complex to promote binding of SIRT2 to cyclin A-Cdk2. Cyclin A-Cdk2 then phosphorylates SIRT2 at Ser331. This phosphorylation reduces SIRT2 catalytic activity and its binding affinity to centrosomes and mitotic spindles, promoting G2-to-M transition. We show that the inhibitory effect of cPLA2α on SIRT2 activity impacts various cellular processes, including cellular levels of histone H4 acetylated at K16 (Ac-H4K16) and Ac-α-tubulin. This regulatory effect of cPLA2α on SIRT2 defines a novel function of cPLA2α independent of its phospholipase activity and may have implications for the impact of SIRT2-related effects on tumorigenesis and age-related diseases.

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MR imaging of model drug distribution in simulated vitreous

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2015-0059 ◽

2015 ◽

Vol 1 (1) ◽

pp. 236-239 ◽

Cited By ~ 2

Author(s):

Sandra Stein ◽

Christian Simroth-Loch ◽

Sönke Langner ◽

Stefan Hadlich ◽

Oliver Stachs ◽

...

Keyword(s):

Molecular Weight ◽

Ex Vivo ◽

Drug Distribution ◽

Injection Technique ◽

Innovative Therapy ◽

Age Related ◽

The Impact

AbstractThe in vitro and in vivo characterization of intravitreal injections plays an important role in developing innovative therapy approaches. Using the established vitreous model (VM) and eye movement system (EyeMoS) the distribution of contrast agents with different molecular weight was studied in vitro. The impact of the simulated age-related vitreal liquefaction (VL) on drug distribution in VM was examined either with injection through the gel phase or through the liquid phase. For comparison the distribution was studied ex vivo in the porcine vitreous. The studies were performed in a magnetic resonance (MR) scanner. As expected, with increasing molecular weight the diffusion velocity and the visual distribution of the injected substances decreased. Similar drug distribution was observed in VM and in porcine eye. VL causes enhanced convective flow and faster distribution in VM. Confirming the importance of the injection technique in progress of VL, injection through gelatinous phase caused faster distribution into peripheral regions of the VM than following injection through liquefied phase. VM and MR scanner in combination present a new approach for the in vitro characterization of drug release and distribution of intravitreal dosage forms.

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Distribution and vulnerability of transcriptional outputs across the genome in Myc-amplified medulloblastoma cells

10.1101/2021.06.07.447394 ◽

2021 ◽

Author(s):

Rui Yang ◽

Wenzhe Wang ◽

Meichen Dong ◽

Kristen Roso ◽

Paula Greer ◽

...

Keyword(s):

Cancer Cells ◽

Tumor Cells ◽

Target Genes ◽

De Novo ◽

Inhibitory Effect ◽

Nucleotide Synthesis ◽

High Level ◽

The Impact

Myc plays a central role in tumorigenesis by orchestrating the expression of genes essential to numerous cellular processes1-4. While it is well established that Myc functions by binding to its target genes to regulate their transcription5, the distribution of the transcriptional output across the human genome in Myc-amplified cancer cells, and the susceptibility of such transcriptional outputs to therapeutic interferences remain to be fully elucidated. Here, we analyze the distribution of transcriptional outputs in Myc-amplified medulloblastoma (MB) cells by profiling nascent total RNAs within a temporal context. This profiling reveals that a major portion of transcriptional action in these cells was directed at the genes fundamental to cellular infrastructure, including rRNAs and particularly those in the mitochondrial genome (mtDNA). Notably, even when Myc protein was depleted by as much as 80%, the impact on transcriptional outputs across the genome was limited, with notable reduction mostly only in genes involved in ribosomal biosynthesis, genes residing in mtDNA or encoding mitochondria-localized proteins, and those encoding histones. In contrast to the limited direct impact of Myc depletion, we found that the global transcriptional outputs were highly dependent on the activity of Inosine Monophosphate Dehydrogenases (IMPDHs), rate limiting enzymes for de novo guanine nucleotide synthesis and whose expression in tumor cells was positively correlated with Myc expression. Blockage of IMPDHs attenuated the global transcriptional outputs with a particularly strong inhibitory effect on infrastructure genes, which was accompanied by the abrogation of MB cells proliferation in vitro and in vivo. Together, our findings reveal a real time action of Myc as a transcriptional factor in tumor cells, provide new insight into the pathogenic mechanism underlying Myc-driven tumorigenesis, and support IMPDHs as a therapeutic vulnerability in cancer cells empowered by a high level of Myc oncoprotein.

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Age-Related Macular Degeneration Revisited: From Pathology and Cellular Stress to Potential Therapies

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2020.612812 ◽

2021 ◽

Vol 8 ◽

Author(s):

Majda Hadziahmetovic ◽

Goldis Malek

Keyword(s):

Macular Degeneration ◽

Vision Loss ◽

Clinical Care ◽

Retinal Pigment ◽

Retinal Pigment Epithelial Cells ◽

Age Related Macular Degeneration ◽

Age Related ◽

The Impact

Age-related macular degeneration (AMD) is a neurodegenerative disease of the aging retina, in which patients experience severe vision loss. Therapies available to patients are limited and are only effective in a sub-population of patients. Future comprehensive clinical care depends on identifying new therapeutic targets and adopting a multi-therapeutic approach. With this goal in mind, this review examines the fundamental concepts underlying the development and progression of AMD and re-evaluates the pathogenic pathways associated with the disease, focusing on the impact of injury at the cellular level, with the understanding that critical assessment of the literature may help pave the way to identifying disease-relevant targets. During this process, we elaborate on responses of AMD vulnerable cells, including photoreceptors, retinal pigment epithelial cells, microglia, and choroidal endothelial cells, based on in vitro and in vivo studies, to select stressful agents, and discuss current therapeutic developments in the field, targeting different aspects of AMD pathobiology.

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Effect of hyperthermia on the viability and proliferative activity of tumor cells

Russian Journal of Oncology ◽

10.18821/1028-9984-2016-21-5-250-252 ◽

2016 ◽

Vol 21 (5) ◽

pp. 250-252

Author(s):

N. Yu Anisimova ◽

M. V Kiselevskiy ◽

Amir G. Abdullaev ◽

N. V Malakhova ◽

S. M Sitdikova ◽

...

Keyword(s):

Tumor Cells ◽

Physiological Activity ◽

Inhibitory Effect ◽

In Vivo Studies ◽

Transformed Cells ◽

Cell Mortality ◽

Temperature Exposure ◽

The Impact

Introduction. Results of the systemic chemotherapy in the peritoneum canceromatosis are unsatisfactory because of poor penetration of anticancer drugs in serous cavities due to the presence ofperitoneal-plasma barrier. One of the possible ways to enhance the action cytostatic agents is the use of chemotherapy and hyperthermia, which, according to some data, has an own cytotoxic effect. The purpose of the study. The study of the effect ofdifferent modes of hyperthermia on the physiological activity of transplantable lines of tumor and non-transformed cells. Results. Analysis of the impact of hyperthermia on the physiological activity of transplantable lines of tumor and the non-transformed cells in vitro and in vivo studies demonstrated that along with the gain in the level and time of the temperature exposure as the degree of damage as tumor cell mortality rate increases. In this study the most effective treatment was as follows: the temperature is above 45°C with the exposure of more than 2 hours, which is difficult to achieve in practice due to the limited tolerance of healthy tissues. Conclusion. With the use of hyperthermia in monoregimen it is not possible to achieve effective levels of the temperature impact, which could hardly have a significant inhibitory effect on tumor cells.

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Inhibition of Group IVA Cytosolic Phospholipase A2by Novel 2-Oxoamides in Vitro, in Cells, and in Vivo

Journal of Medicinal Chemistry ◽

10.1021/jm030485c ◽

2004 ◽

Vol 47 (14) ◽

pp. 3615-3628 ◽

Cited By ~ 67

Author(s):

George Kokotos ◽

David A. Six ◽

Vassilios Loukas ◽

Timothy Smith ◽

Violetta Constantinou-Kokotou ◽

...

Keyword(s):

Cytosolic Phospholipase ◽

Group Iva ◽

In Cells

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P11.07 LAPTM5 functions as a tumor suppressor via CD40 - NFêB pathway inhibition and represents a potential biomarker for temozolomide sensitivity in CD40 proficient glioblastoma

Neuro-Oncology ◽

10.1093/neuonc/noz126.153 ◽

2019 ◽

Vol 21 (Supplement_3) ◽

pp. iii43-iii43

Author(s):

A Berberich ◽

F Bartels ◽

Z Tang ◽

S Pusch ◽

N Hucke ◽

...

Keyword(s):

Tumor Suppressor ◽

Treatment Resistance ◽

High Grade Glioma ◽

Expression Array ◽

Potential Biomarker ◽

Nfκb Pathway ◽

Pathway Inhibition ◽

The Impact

Abstract BACKGROUND Glioma therapy is challenged by the invasive nature of glioma resulting in tumor recurrence and treatment resistance. Lysosomal protein transmembrane 5 (LAPTM5) was identified to inhibit invasion by screening for invasion-associated genes in glioma. The aim of this study was to decipher the function of LAPTM5 in glioblastoma and its interaction with the CD40 receptor which was shown to be highly expressed in up to 40% of glioblastoma. METHODS LAPTM5 expression was correlated with clinical outcome of glioma patients. Knockdown of LAPTM5 was performed in different glioma cell lines to analyze the impact on clonogenicity, invasiveness, sensitivity to temozolomide chemotherapy and tumorigenicity in-vitro and in-vivo in a subcutaneous xenograft mouse model. Expression array was used to elucidate the underlying pathways. CD40 knockdown and overexpression was induced to prove the crosstalk of LAPTM5 and CD40. RESULTS LAPTM5 expression correlated with better overall survival in high grade glioma patients and acted as a tumor suppressor in CD40 positive glioblastoma cells. LAPTM5 inhibited CD40-mediated NFκB activation resulting in anti-invasive, anti-clonogenic and temozolomide sensitizing effects in-vitro and in-vivo. Vice-versa, knockdown of LAPTM5 enhanced tumorigenicity by activation of the NFκB pathway which was overcome by NFκB inhibition. Importantly, CD40 expression was required for LAPTM5-mediated tumor suppressive activity. CONCLUSION LAPTM5 conveyed tumor suppressive and temozolomide sensitizing effects in CD40-positive glioblastoma by inhibition of CD40-mediated NFκB activation and thereby might provide a reasonable biomarker for sensitivity to temozolomide in CD40-positive glioblastoma.

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Angptl2 is a Marker of Cellular Senescence: The Physiological and Pathophysiological Impact of Angptl2-Related Senescence

International Journal of Molecular Sciences ◽

10.3390/ijms222212232 ◽

2021 ◽

Vol 22 (22) ◽

pp. 12232

Author(s):

Nathalie Thorin-Trescases ◽

Pauline Labbé ◽

Pauline Mury ◽

Mélanie Lambert ◽

Eric Thorin

Keyword(s):

Cell Fate ◽

Cellular Senescence ◽

Cellular Response ◽

Inflammatory Diseases ◽

Age Related ◽

A Cell ◽

Future Work ◽

The Impact

Cellular senescence is a cell fate primarily induced by DNA damage, characterized by irreversible growth arrest in an attempt to stop the damage. Senescence is a cellular response to a stressor and is observed with aging, but also during wound healing and in embryogenic developmental processes. Senescent cells are metabolically active and secrete a multitude of molecules gathered in the senescence-associated secretory phenotype (SASP). The SASP includes inflammatory cytokines, chemokines, growth factors and metalloproteinases, with autocrine and paracrine activities. Among hundreds of molecules, angiopoietin-like 2 (angptl2) is an interesting, although understudied, SASP member identified in various types of senescent cells. Angptl2 is a circulatory protein, and plasma angptl2 levels increase with age and with various chronic inflammatory diseases such as cancer, atherosclerosis, diabetes, heart failure and a multitude of age-related diseases. In this review, we will examine in which context angptl2 was identified as a SASP factor, describe the experimental evidence showing that angptl2 is a marker of senescence in vitro and in vivo, and discuss the impact of angptl2-related senescence in both physiological and pathological conditions. Future work is needed to demonstrate whether the senescence marker angptl2 is a potential clinical biomarker of age-related diseases.

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Corynebacterium Species Inhibit Streptococcus pneumoniae Colonization and Infection of the Mouse Airway

Frontiers in Microbiology ◽

10.3389/fmicb.2021.804935 ◽

2022 ◽

Vol 12 ◽

Author(s):

Kadi J. Horn ◽

Alexander C. Jaberi Vivar ◽

Vera Arenas ◽

Sameer Andani ◽

Edward N. Janoff ◽

...

Keyword(s):

Streptococcus Pneumoniae ◽

Respiratory Health ◽

Upper Airway ◽

Inhibitory Effect ◽

Airway Microbiome ◽

The Stability ◽

Independent Effects ◽

The Impact

The stability and composition of the airway microbiome is an important determinant of respiratory health. Some airway bacteria are considered to be beneficial due to their potential to impede the acquisition and persistence of opportunistic bacterial pathogens such as Streptococcus pneumoniae. Among such organisms, the presence of Corynebacterium species correlates with reduced S. pneumoniae in both adults and children, in whom Corynebacterium abundance is predictive of S. pneumoniae infection risk. Previously, Corynebacterium accolens was shown to express a lipase which cleaves host lipids, resulting in the production of fatty acids that inhibit growth of S. pneumoniae in vitro. However, it was unclear whether this mechanism contributes to Corynebacterium-S. pneumoniae interactions in vivo. To address this question, we developed a mouse model for Corynebacterium colonization in which colonization with either C. accolens or another species, Corynebacterium amycolatum, significantly reduced S. pneumoniae acquisition in the upper airway and infection in the lung. Moreover, the lungs of co-infected mice had reduced pro-inflammatory cytokines and inflammatory myeloid cells, indicating resolution of infection-associated inflammation. The inhibitory effect of C. accolens on S. pneumoniae in vivo was mediated by lipase-dependent and independent effects, indicating that both this and other bacterial factors contribute to Corynebacterium-mediated protection in the airway. We also identified a previously uncharacterized bacterial lipase in C. amycolatum that is required for inhibition of S. pneumoniae growth in vitro. Together, these findings demonstrate the protective potential of airway Corynebacterium species and establish a new model for investigating the impact of commensal microbiota, such as Corynebacterium, on maintaining respiratory health.

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BIOL-10. DISTRIBUTION AND VULNERABILITY OF TRANSCRIPTIONAL OUTPUTS ACROSS THE GENOME IN MYC-AMPLIFIED MEDULLOBLASTOMA CELLS

Neuro-Oncology ◽

10.1093/neuonc/noab090.017 ◽

2021 ◽

Vol 23 (Supplement_1) ◽

pp. i5-i5

Author(s):

Rui Yang ◽

Wenzhe Wang ◽

Meichen Dong ◽

Kristen Roso ◽

Xuhui Bao ◽

...

Keyword(s):

Tumor Cells ◽

Target Genes ◽

De Novo ◽

Inhibitory Effect ◽

Nucleotide Synthesis ◽

Expression Of Genes ◽

High Level ◽

The Impact

Abstract Myc plays a central role in tumorigenesis by orchestrating the expression of genes essential to numerous cellular processes. While it is well established that Myc functions by binding to its target genes to regulate their transcription, the distribution of the transcriptional output across human genome in Myc-amplified cancer cells, and the susceptibility of such transcriptional outputs to therapeutic interferences remain to be fully elucidated. Here, we analyze the distribution of transcriptional outputs in Myc-amplified medulloblastoma (MB) cells by profiling nascent total RNAs within a temporal context. This profiling reveals a major portion of transcriptional action in these cells was directed at the genes fundamental to cellular infrastructures, including rRNAs and particularly those in the mitochondrial genome (mtDNA). Notably, even when Myc protein was depleted by as much as 80%, the impact on transcriptional outputs across the genome was limited, with notable reduction mostly in genes of involved in ribosomal biosynthesis, genes residing in mtDNA or encoding mitochondria-localized proteins, and those encoding histones. In contrast to the limited direct impact of Myc depletion, we found that the global transcriptional outputs were highly dependent on the activity of Inosine Monophosphate Dehydrogenases (IMPDHs), rate limiting enzymes for de novo guanine nucleotide synthesis and whose expression in tumor cells was positively correlated with Myc’s expression. Blockage of IMPDHs attenuated the global transcriptional outputs with a particularly strong inhibitory effect on the aforementioned infrastructure genes, which was accompanied by the abrogation of MB cell’s proliferation in vitro and in vivo. Together, our findings reveal a real time action of Myc as a transcriptional factor in tumor cells, gain new insight into the pathogenic mechanism underlying Myc-driven tumorigenesis, and support IMPDHs as a therapeutic vulnerability in MB cells empowered by a high level of Myc oncoprotein.

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Impact of mTOR Inhibition on FoxP3+ Regulatory T Cells as Compared to Conventional T Cells after Allogeneic Bone Marrow Transplantation.

Blood ◽

10.1182/blood.v108.11.448.448 ◽

2006 ◽

Vol 108 (11) ◽

pp. 448-448 ◽

Cited By ~ 1

Author(s):

Robert Zeiser ◽

Dennis B. Leveson-Gower ◽

Elizabeth A. Zambricki ◽

Jing-Zhou Hou ◽

Robert Negrin

Keyword(s):

Clinical Trials ◽

T Cells ◽

Regulatory T Cells ◽

Allogeneic Bone Marrow Transplantation ◽

Inhibitory Effect ◽

Allogeneic Bone ◽

Mtor Inhibition ◽

The Impact

Abstract FoxP3+CD4+CD25+ regulatory T-cells (Treg) have been shown to effectively reduce the severity of experimental acute graft-versus-host disease (aGvHD) while sparing graft-versus-leukemia activity. These findings, in concert with the observation that human and murine Treg share functional characteristics, have fueled interest in clinical trials to control aGvHD. Recent data indicates that the immunosuppressant rapamycin (RAPA) in contrast to cyclosporine A does not interfere with in vivo function of Treg and could enhance Treg expansion in vitro by a yet unknown mechanism. To investigate the impact of mTOR inhibition on proliferating Treg and Tconv, both cell types were exposed to CD3/CD28 Mabs in the presence of different RAPA concentrations in vitro. Phosphorylation of mTOR downstream products p70S6K1 and 4E-BP1 were assessed by western blot and flow cytometry. Inhibition of the phosphorylation of p70S6K1 and 4E-BP1 was observed in both populations in the presence of RAPA. Interestingly, Treg were more resistant to mTOR inhibition as compared to Tconv and displayed significantly higher phosphorylated products in the presence of RAPA at 10 nM (MFI Treg vs Tconv, p<0.001) and at 100nM (MFI Treg vs Tconv, p<0.001). To investigate whether Treg and RAPA protect from aGvHD in a synergistic manner, BALB/c recipients were transplanted with H-2 disparate BM and 1.6x10e6 T-cells (FVB/N) after lethal irradiation (8 Gy). aGvHD lethality was only slightly reduced when suboptimal Tconv:Treg ratios were employed (4:1, 8:1), or when recipients were treated with a non-protective RAPA dose (0.5 mg/kg bodyweight). Combining a suboptimal Tconv:Treg ratio with a non-protective RAPA dose reduced expansion of luciferase expressing (luc+) Tconv and pro-inflamatory cytokines and improved survival indicative for an additive in vivo effect of RAPA and Treg. To evaluate the impact of RAPA on in vivo T cell expansion, either luc+ Tconv or luc+ Treg were adoptively transferred. In vivo bioluminescence imaging demonstrated that RAPA had a more potent inhibitory effect on proliferation of Tconv as compared to Treg (p<0.05 vs. NS). We did not observe RAPA to increase FoxP3+ Treg numbers in vivo, or to enhance GITR or CTLA-4 expression. Thus, increased Treg numbers observed in RAPA containing expansion cultures are likely due to a lower susceptibility of this cell population to mTOR inhibition. This could explain the observed synergistic effect of RAPA and Treg in aGvHD protection which has relevance for clinical trials utilizing Treg to prevent aGvHD.

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