scholarly journals Bi-allelic MCM10 variants associated with immune dysfunction and cardiomyopathy cause telomere shortening

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ryan M. Baxley ◽  
Wendy Leung ◽  
Megan M. Schmit ◽  
Jacob Peter Matson ◽  
Lulu Yin ◽  
...  
Keyword(s):  
Immune Cell ◽  
Nk Cell ◽  
Restrictive Cardiomyopathy ◽  
Telomerase Activity ◽  
Compound Heterozygous ◽  
Minichromosome Maintenance ◽  
Telomere Shortening ◽  
Clinical Phenotypes ◽  
Eukaryotic Dna ◽  
Minichromosome Maintenance Protein

AbstractMinichromosome maintenance protein 10 (MCM10) is essential for eukaryotic DNA replication. Here, we describe compound heterozygous MCM10 variants in patients with distinctive, but overlapping, clinical phenotypes: natural killer (NK) cell deficiency (NKD) and restrictive cardiomyopathy (RCM) with hypoplasia of the spleen and thymus. To understand the mechanism of MCM10-associated disease, we modeled these variants in human cell lines. MCM10 deficiency causes chronic replication stress that reduces cell viability due to increased genomic instability and telomere erosion. Our data suggest that loss of MCM10 function constrains telomerase activity by accumulating abnormal replication fork structures enriched with single-stranded DNA. Terminally-arrested replication forks in MCM10-deficient cells require endonucleolytic processing by MUS81, as MCM10:MUS81 double mutants display decreased viability and accelerated telomere shortening. We propose that these bi-allelic variants in MCM10 predispose specific cardiac and immune cell lineages to prematurely arrest during differentiation, causing the clinical phenotypes observed in both NKD and RCM patients.

scholarly journals Bi-allelic MCM10 mutations cause telomere shortening with immune dysfunction and cardiomyopathy

2019 ◽  
Author(s):  
Ryan M. Baxley ◽  
Wendy Leung ◽  
Megan M. Schmit ◽  
Jacob Peter Matson ◽  
Marissa K. Oram ◽  
...  
Keyword(s):  
Immune Cell ◽  
Nk Cell ◽  
Restrictive Cardiomyopathy ◽  
Telomerase Activity ◽  
Compound Heterozygous ◽  
Minichromosome Maintenance ◽  
Telomere Shortening ◽  
Clinical Phenotypes ◽  
Eukaryotic Dna ◽  
Minichromosome Maintenance Protein

ABSTRACTMinichromosome maintenance protein 10 (Mcm10) is essential for eukaryotic DNA replication. Here, we describe compound heterozygous MCM10 mutations in patients with distinctive but overlapping clinical phenotypes – natural killer (NK) cell deficiency (NKD) and restrictive cardiomyopathy (RCM) with hypoplasia of the spleen and thymus. To understand the mechanism of Mcm10-associated disease, we modeled these mutations in human cell lines. Mcm10 deficiency causes chronic replication stress that reduces cell viability due to increased genomic instability and telomere erosion. Our data suggest that loss of Mcm10 function constrains telomerase activity by accumulating abnormal replication fork structures enriched with single-stranded DNA. Terminally-arrested replication forks in Mcm10-deficient cells require endonucleolytic processing by Mus81, as MCM10:MUS81 double mutants display decreased viability and accelerated telomere shortening. We propose that these bi-allelic mutations in MCM10 predispose specific cardiac and immune cell lineages to prematurely arrest during differentiation, causing the clinical phenotypes in both NKD and CM patients.

scholarly journals Chronic stress elevates telomerase activity in rats

2012 ◽  
Vol 8 (6) ◽  
pp. 1063-1066 ◽  
Author(s):  
Annaliese K. Beery ◽  
Jue Lin ◽  
Joshua S. Biddle ◽  
Darlene D. Francis ◽  
Elizabeth H. Blackburn ◽  
...  
Keyword(s):  
Chronic Stress ◽  
Dna Sequences ◽  
Replicative Senescence ◽  
Immune Cell ◽  
Telomerase Activity ◽  
Male Rats ◽  
Repetitive Dna Sequences ◽  
Potential Mechanism ◽  
Telomere Shortening ◽  
Protective Structures

The enzyme telomerase lengthens telomeres—protective structures containing repetitive DNA sequences at chromosome ends. Telomere shortening is associated with diseases of ageing in mammals. Chronic stress has been related to shorter immune-cell telomeres, but telomerase activity under stress may be low, permitting telomere loss, or high, partially attenuating it. We developed an experimental model to examine the impacts of extended unpredictable stress on telomerase activity in male rats. Telomerase activity was 54 per cent higher in stressed rats than in controls, and associated with stress-related physiological and behavioural outcomes. This significant increase suggests a potential mechanism for resilience to stress-related replicative senescence.

scholarly journals Ciprofloxacin is an inhibitor of the Mcm2-7 replicative helicase

2013 ◽  
Vol 33 (5) ◽  
Author(s):  
Nicholas Simon ◽  
Matthew L. Bochman ◽  
Sandlin Seguin ◽  
Jeffrey L. Brodsky ◽  
William L. Seibel ◽  
...  
Keyword(s):  
Dna Replication ◽  
Dna Helicase ◽  
Dna Unwinding ◽  
Helicase Activity ◽  
Minichromosome Maintenance ◽  
Replicative Helicase ◽  
Eukaryotic Dna ◽  
Minichromosome Maintenance Protein ◽  
Ciprofloxacin Resistance

Most currently available small molecule inhibitors of DNA replication lack enzymatic specificity, resulting in deleterious side effects during use in cancer chemotherapy and limited experimental usefulness as mechanistic tools to study DNA replication. Towards development of targeted replication inhibitors, we have focused on Mcm2-7 (minichromosome maintenance protein 2–7), a highly conserved helicase and key regulatory component of eukaryotic DNA replication. Unexpectedly we found that the fluoroquinolone antibiotic ciprofloxacin preferentially inhibits Mcm2-7. Ciprofloxacin blocks the DNA helicase activity of Mcm2-7 at concentrations that have little effect on other tested helicases and prevents the proliferation of both yeast and human cells at concentrations similar to those that inhibit DNA unwinding. Moreover, a previously characterized mcm mutant (mcm4chaos3) exhibits increased ciprofloxacin resistance. To identify more potent Mcm2-7 inhibitors, we screened molecules that are structurally related to ciprofloxacin and identified several that compromise the Mcm2-7 helicase activity at lower concentrations. Our results indicate that ciprofloxacin targets Mcm2-7 in vitro, and support the feasibility of developing specific quinolone-based inhibitors of Mcm2-7 for therapeutic and experimental applications.

scholarly journals Natural Killer Cells Are Present in Rag1−/− Mice and Promote Tissue Damage During the Acute Phase of Ischemic Stroke

2021 ◽  
Author(s):  
Leoni Rolfes ◽  
Tobias Ruck ◽  
Christina David ◽  
Stine Mencl ◽  
Stefanie Bock ◽  
...  
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Adoptive Transfer ◽  
Immune Cell ◽  
Nk Cell ◽  
Cell Subset ◽  
Neurological Deficits ◽  
In Vitro Assays ◽  
Experimental Stroke ◽  
Transfer Model

AbstractRag1−/− mice, lacking functional B and T cells, have been extensively used as an adoptive transfer model to evaluate neuroinflammation in stroke research. However, it remains unknown whether natural killer (NK) cell development and functions are altered in Rag1−/− mice as well. This connection has been rarely discussed in previous studies but might have important implications for data interpretation. In contrast, the NOD-Rag1nullIL2rgnull (NRG) mouse model is devoid of NK cells and might therefore eliminate this potential shortcoming. Here, we compare immune-cell frequencies as well as phenotype and effector functions of NK cells in Rag1−/− and wildtype (WT) mice using flow cytometry and functional in vitro assays. Further, we investigate the effect of Rag1−/− NK cells in the transient middle cerebral artery occlusion (tMCAO) model using antibody-mediated depletion of NK cells and adoptive transfer to NRG mice in vivo. NK cells in Rag1−/− were comparable in number and function to those in WT mice. Rag1−/− mice treated with an anti-NK1.1 antibody developed significantly smaller infarctions and improved behavioral scores. Correspondingly, NRG mice supplemented with NK cells were more susceptible to tMCAO, developing infarctions and neurological deficits similar to Rag1−/− controls. Our results indicate that NK cells from Rag1−/− mice are fully functional and should therefore be considered in the interpretation of immune-cell transfer models in experimental stroke. Fortunately, we identified the NRG mice, as a potentially better-suited transfer model to characterize individual cell subset-mediated neuroinflammation in stroke.

scholarly journals 114 Preclinical development of a novel iPSC-derived CAR-MICA/B NK cell immunotherapy to overcome solid tumor escape from NKG2D-mediated mechanisms of recognition and killing

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A126-A126
Author(s):  
John Goulding ◽  
Mochtar Pribadi ◽  
Robert Blum ◽  
Wen-I Yeh ◽  
Yijia Pan ◽  
...  
Keyword(s):  
T Cells ◽  
Cancer Immunotherapy ◽  
Tumor Immunity ◽  
Immune Cell ◽  
Nk Cell ◽  
Tumor Escape ◽  
Car T Cells ◽  
Car T

BackgroundMHC class I related proteins A (MICA) and B (MICB) are induced by cellular stress and transformation, and their expression has been reported for many cancer types. NKG2D, an activating receptor expressed on natural killer (NK) and T cells, targets the membrane-distal domains of MICA/B, activating a potent cytotoxic response. However, advanced cancer cells frequently evade immune cell recognition by proteolytic shedding of the α1 and α2 domains of MICA/B, which can significantly reduce NKG2D function and the cytolytic activity.MethodsRecent publications have shown that therapeutic antibodies targeting the membrane-proximal α3 domain inhibited MICA/B shedding, resulting in a substantial increase in the cell surface density of MICA/B and restoration of immune cell-mediated tumor immunity.1 We have developed a novel chimeric antigen receptor (CAR) targeting the conserved α3 domain of MICA/B (CAR-MICA/B). Additionally, utilizing our proprietary induced pluripotent stem cell (iPSC) product platform, we have developed multiplexed engineered, iPSC-derived CAR-MICA/B NK (iNK) cells for off-the-shelf cancer immunotherapy.ResultsA screen of CAR spacer and ScFv orientations in primary T cells delineated MICA-specific in vitro activation and cytotoxicity as well as in vivo tumor control against MICA+ cancer cells. The novel CAR-MICA/B design was used to compare efficacy against NKG2D CAR T cells, an alternative MICA/B targeting strategy. CAR-MICA/B T cells showed superior cytotoxicity against melanoma, breast cancer, renal cell carcinoma, and lung cancer lines in vitro compared to primary NKG2D CAR T cells (p<0.01). Additionally, using an in vivo xenograft metastasis model, CAR-MICA/B T cells eliminated A2058 human melanoma metastases in the majority of the mice treated. In contrast, NKG2D CAR T cells were unable to control tumor growth or metastases. To translate CAR-MICA/B functionality into an off-the-shelf cancer immunotherapy, CAR-MICA/B was introduced into a clonal master engineered iPSC line to derive a multiplexed engineered, CAR-MICA/B iNK cell product candidate. Using a panel of tumor cell lines expressing MICA/B, CAR-MICA/B iNK cells displayed MICA specificity, resulting in enhanced cytokine production, degranulation, and cytotoxicity. Furthermore, in vivo NK cell cytotoxicity was evaluated using the B16-F10 melanoma cell line, engineered to express MICA. In this model, CAR-MICA/B iNK cells significantly reduced liver and lung metastases, compared to untreated controls, by 93% and 87% respectively.ConclusionsOngoing work is focused on extending these preclinical studies to further support the clinical translation of an off-the-shelf, CAR-MICA/B iNK cell cancer immunotherapy with the potential to overcome solid tumor escape from NKG2D-mediated mechanisms of recognition and killing.ReferenceFerrari de Andrade L, Tay RE, Pan D, Luoma AM, Ito Y, Badrinath S, Tsoucas D, Franz B, May KF Jr, Harvey CJ, Kobold S, Pyrdol JW, Yoon C, Yuan GC, Hodi FS, Dranoff G, Wucherpfennig KW. Antibody-mediated inhibition of MICA and MICB shedding promotes NK cell-driven tumor immunity. Science 2018 Mar 30;359(6383):1537–1542.

scholarly journals Sex- and age‐dependent alterations of splenic immune cell profile and NK cell phenotypes and function in C57BL/6J mice

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Kelly B. Menees ◽  
Rachael H. Earls ◽  
Jaegwon Chung ◽  
Janna Jernigan ◽  
Nikolay M. Filipov ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Sex Differences ◽  
Nk Cells ◽  
Immune Cell ◽  
Nk Cell ◽  
Spleen Weight ◽  
Age Related ◽  
And Function ◽  
Cell Phenotypes

Abstract Background Physiological homeostasis decline, immunosenescence, and increased risk for multiple diseases, including neurodegeneration, are all hallmarks of ageing. Importantly, it is known that the ageing process is sex-biased. For example, there are sex differences in predisposition for multiple age-related diseases, including neurodegenerative and autoimmune diseases. However, sex differences in age-associated immune phenotypes are not clearly understood. Results Here, we examined the effects of age on immune cell phenotypes in both sexes of C57BL/6J mice with a particular focus on NK cells. We found female-specific spleen weight increases with age and concordant reduction in the number of splenocytes per gram of spleen weight compared to young females. To evaluate sex- and age-associated changes in splenic immune cell composition, we performed flow cytometry analysis. In male mice, we observed an age-associated reduction in the frequencies of monocytes and NK cells; female mice displayed a reduction in B cells, NK cells, and CD8 + T cells and increased frequency of monocytes and neutrophils with age. We then performed a whole blood stimulation assay and multiplex analyses of plasma cytokines and observed age- and sex-specific differences in immune cell reactivity and basal circulating cytokine concentrations. As we have previously illustrated a potential role of NK cells in Parkinson’s disease, an age-related neurodegenerative disease, we further analyzed age-associated changes in NK cell phenotypes and function. There were distinct differences between the sexes in age-associated changes in the expression of NK cell receptors, IFN-γ production, and impairment of α-synuclein endocytosis. Conclusions This study demonstrates sex- and age-specific alterations in splenic lymphocyte composition, circulating cytokine/chemokine profiles, and NK cell phenotype and effector functions. Our data provide evidence that age-related physiological perturbations differ between the sexes which may help elucidate sex differences in age-related diseases, including neurodegenerative diseases, particularly Parkinson’s disease, where immune dysfunction is implicated in their etiology.

scholarly journals Telomerase activation in mouse mammary tumors: lack of detectable telomere shortening and evidence for regulation of telomerase RNA with cell proliferation.

1996 ◽  
Vol 16 (7) ◽  
pp. 3765-3772 ◽  
Author(s):  
D Broccoli ◽  
L A Godley ◽  
L A Donehower ◽  
H E Varmus ◽  
T de Lange
Keyword(s):  
Cell Proliferation ◽  
Tumor Development ◽  
Mammary Tumorigenesis ◽  
Mammary Tumors ◽  
Mammary Glands ◽  
Telomerase Activity ◽  
Telomerase Rna ◽  
Proliferating Cells ◽  
Telomere Shortening ◽  
Mouse Mammary Tumors

Activation of telomerase in human cancers is thought to be necessary to overcome the progressive loss of telomeric DNA that accompanies proliferation of normal somatic cells. According to this model, telomerase provides a growth advantage to cells in which extensive terminal sequence loss threatens viability. To test these ideas, we have examined telomere dynamics and telomerase activation during mammary tumorigenesis in mice carrying a mouse mammary tumor virus long terminal repeat-driven Wnt-1 transgene. We also analyzed Wnt-1-induced mammary tumors in mice lacking p53 function. Normal mammary glands, hyperplastic mammary glands, and mammary carcinomas all had the long telomeres (20 to 50 kb) typical of Mus musculus and did not show telomere shortening during tumor development. Nevertheless, telomerase activity and the RNA component of the enzyme were consistently upregulated in Wnt-1-induced mammary tumors compared with normal and hyperplastic tissues. The upregulation of telomerase activity and RNA also occurred during tumorigenesis in p53-deficient mice. The expression of telomerase RNA correlated strongly with histone H4 mRNA in all normal tissues and tumors, indicating that the RNA component of telomerase is regulated with cell proliferation. Telomerase activity in the tumors was elevated to a greater extent than telomerase RNA, implying that the enzymatic activity of telomerase is regulated at additional levels. Our data suggest that the mechanism of telomerase activation in mouse mammary tumors is not linked to global loss of telomere function but involves multiple regulatory events including upregulation of telomerase RNA in proliferating cells.

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