scholarly journals Tomatine Displays Antitumor Potential in In Vitro Models of Metastatic Melanoma

2020 ◽  
Vol 21 (15) ◽  
pp. 5243 ◽  
Author(s):  
Simona Serratì ◽  
Letizia Porcelli ◽  
Stefania Guida ◽  
Anna Ferretta ◽  
Rosa Maria Iacobazzi ◽  
...  
Keyword(s):  
Metastatic Melanoma ◽  
Cell Lines ◽  
Cell Invasion ◽  
Capillary Tube ◽  
Tube Formation ◽  
Boyden Chamber ◽  
Wild Type ◽  
Antitumor Potential ◽  
Vegf Release

There is a growing interest in the cytotoxic effects of bioactive glycoalkaloids, such as α-tomatine on tumor cells. Here, for the first time, we determine the antitumor potential of tomatine, a mixture of α-tomatine and dehydrotomatine, in metastatic melanoma (MM) cell lines harboring different BRAF and MC1R variants. We performed cytotoxicity experiments and annexin-V/propidium iodide staining to assess the apoptotic/necrotic status of the cells. ER stress and autophagy markers were revealed by Western Blot, whereas antiangiogenic and vascular-disrupting effects were evaluated through a capillary tube formation assay on matrigel and by ELISA kit for VEGF release determination. Cell invasion was determined by a Boyden chamber matrigel assay. Tomatine reduced 50% of cell viability and induced a concentration-dependent increase of apoptotic cells in the range of 0.5–1 μM in terms of α-tomatine. The extent of apoptosis was more than two-fold higher in V600BRAF-D184H/D184H MC1R cells than in BRAF wild-type cells and V600BRAF-MC1R wild-type cell lines. Additionally, tomatine increased the LC3I/II autophagy marker, p-eIF2α, and p-Erk1/2 levels in BRAF wild-type cells. Notably, tomatine strongly reduced cell invasion and melanoma-dependent angiogenesis by reducing VEGF release and tumor-stimulating effects on capillary tube formation. Collectively, our findings support tomatine as a potential antitumor agent in MM.

scholarly journals Anti-Metastatic and Anti-Angiogenic Effects of Curcumin Analog DK1 on Human Osteosarcoma Cells In Vitro

2021 ◽  
Vol 14 (6) ◽  
pp. 532
Author(s):  
Muhammad Nazirul Mubin Aziz ◽  
Nurul Fattin Che Rahim ◽  
Yazmin Hussin ◽  
Swee Keong Yeap ◽  
Mas Jaffri Masarudin ◽  
...  
Keyword(s):  
Cell Lines ◽  
Safety Profile ◽  
Quantitative Polymerase Chain Reaction ◽  
Tube Formation ◽  
Osteosarcoma Cell ◽  
Curcumin Analog ◽  
Human Osteosarcoma ◽  
Human Osteosarcoma Cells ◽  
Human Osteosarcoma Cell

Osteosarcoma (OS) is a life-threatening malignant bone tumor associated with poor prognosis among children. The survival rate of the patient is still arguably low even with intensive treatment provided, plus with the inherent side effects from the chemotherapy, which gives more unfavorable outcomes. Hence, the search for potent anti-osteosarcoma agent with promising safety profile is still on going. Natural occurring substance like curcumin has gained a lot of attention due to its splendid safety profile as well as it pharmacological advantages such as anti-metastasis and anti-angiogenesis. However, natural curcumin was widely known for its poor cellular uptake, which undermines all potential that it possesses. This prompted the development of synthetically synthesized curcuminoid analog, known as (Z)-3-hydroxy-1-(2-hydroxyphenyl)-3-phenylprop-2- en-1-one (DK1). In this present study, in vitro scratch assay, transwell migration/invasion assay, HUVEC tube formation assay, and ex vivo rat aortic ring assays were performed in order to investigate the anti-metastatic and anti-angiogenic potential of DK1. For further comprehension of DK1 mechanism on human osteosarcoma cell lines, microarray gene expression analysis, quantitative polymerase chain reaction (qPCR), and proteome profiler were adopted, providing valuable forecast from the expression of important genes and proteins related to metastasis and angiogenesis. Based on the data gathered from the bioassays, DK1 was able to inhibit the metastasis and angiogenesis of human osteosarcoma cell lines by significantly reducing the cell motility, number of migrated and invaded cells as well as the tube formation and micro-vessels sprouting. Additionally, DK1 also has significantly regulated several cancer pathways involved in OS proliferation, metastasis, and angiogenesis such as PI3K/Akt and NF-κB in both U-2 OS and MG-63. Regulation of PI3K/Akt caused up-regulation of genes related to metastasis inhibition, namely, PTEN, FOXO, PLK3, and GADD45A. Meanwhile, NF-κB pathway was regulated by mitigating the expression of NF-κB activator such as IKBKB and IKBKE in MG-63, whilst up-regulating the expression of NF-κB inhibitors such as NFKBIA and NFKBIE in U-2 OS. Finally, DK1 also has successfully hindered the metastatic and angiogenic capability of OS cell lines by down-regulating the expression of pro-metastatic genes and proteins like MMP3, COL11A1, FGF1, Endoglin, uPA, and IGFBP2 in U-2 OS. Whilst for MG-63, the significantly down-regulated oncogenes were Serpin E1, AKT2, VEGF, uPA, PD-ECGF, and Endoglin. These results suggest that curcumin analog DK1 may serve as a potential new anti-osteosarcoma agent due to its anti-metastatic and anti-angiogenic attributes.

scholarly journals Mechanism of MicroRNA-375 Promoter Methylation in Promoting Ovarian Cancer Cell Malignancy

2021 ◽  
Vol 20 ◽  
pp. 153303382098011
Author(s):  
Junjun Shu ◽  
Ling Xiao ◽  
Sanhua Yan ◽  
Boqun Fan ◽  
Xia Zou ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Protein Expression ◽  
Cell Lines ◽  
Cell Invasion ◽  
Promoter Methylation ◽  
Luciferase Reporter ◽  
Luciferase Reporter Gene ◽  
Gene Assay ◽  
Cell Malignancy

Objective: Ovarian cancer (OC) ranks one of the most prevalent fatal tumors of female genital organs. Aberrant promoter methylation triggers changes of microRNA (miR)-375 in OC. Our study aimed to evaluate the mechanism of methylated miR-375 promoter region in OC cell malignancy and to seek the possible treatment for OC. Methods: miR-375 promoter methylation level in OC tissues and cells was detected. miR-375 expression in OC tissues and cell lines was compared with that in demethylated cells. Role of miR-375 in OC progression was measured. Dual-luciferase reporter gene assay was utilized to verify the targeting relationship between miR-375 and Yes-associated protein 1 (YAP1). Then, Wnt/β-catenin pathway-related protein expression was tested. Moreover, xenograft transplantation was applied to confirm the in vitro experiments. Results: Highly methylated miR-375 was seen in OC tissues and cell lines, while its expression was decreased as the promoter methylation increased. Demethylation in OC cells brought miR-375 back to normal level, with obviously declined cell invasion, migration and viability and improved apoptosis. Additionally, miR-375 targeted YAP1 to regulate the Wnt/β-catenin pathway protein expression. Overexpressed YAP1 reversed the protein expression, promoted cell invasion, migration and viability while reduced cell apoptosis. Overexpressed miR-375 in vivo inhibited OC progression. Conclusion: Our study demonstrated that demethylated miR-375 inhibited OC growth by targeting YAP1 and downregulating the Wnt/β-catenin pathway. This investigation may offer novel insight for OC treatment.

scholarly journals Novel Nargenicin A1 Analog Inhibits Angiogenesis by Downregulating the Endothelial VEGF/VEGFR2 Signaling and Tumoral HIF-1α/VEGF Pathway

Biomedicines ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 252
Author(s):  
Jang Mi Han ◽  
Ye Seul Choi ◽  
Dipesh Dhakal ◽  
Jae Kyung Sohng ◽  
Hye Jin Jung
Keyword(s):  
Capillary Tube ◽  
Umbilical Vein ◽  
Hypoxia Inducible Factor ◽  
Chorioallantoic Membrane ◽  
Tube Formation ◽  
Ags Cells ◽  
Vegf Pathway ◽  
Vegfr2 Signaling

Targeting angiogenesis is an attractive strategy for the treatment of angiogenesis-related diseases, including cancer. We previously identified 23-demethyl 8,13-deoxynargenicin (compound 9) as a novel nargenicin A1 analog with potential anticancer activity. In this study, we investigated the antiangiogenic activity and mode of action of compound 9. This compound was found to effectively inhibit in vitro angiogenic characteristics, including the proliferation, invasion, capillary tube formation, and adhesion of human umbilical vein endothelial cells (HUVECs) stimulated by vascular endothelial growth factor (VEGF). Furthermore, compound 9 suppressed the neovascularization of the chorioallantoic membrane of growing chick embryos in vivo. Notably, the antiangiogenic properties of compound 9 were related to the downregulation of VEGF/VEGFR2-mediated downstream signaling pathways, as well as matrix metalloproteinase (MMP)-2 and MMP-9 expression in HUVECs. In addition, compound 9 was found to decrease the in vitro AGS gastric cancer cell-induced angiogenesis of HUVECs by blocking hypoxia-inducible factor-1α (HIF-1α) and VEGF expression in AGS cells. Collectively, our findings demonstrate for the first time that compound 9 is a promising antiangiogenic agent targeting both VEGF/VEGFR2 signaling in ECs and HIF-1α/VEGF pathway in tumor cells.

Abstract 34: Human Cardiac Mesenchymal Cell Derived Extracellular Vesicles Promote Angiogenesis Through Angiopoietin-TIE2 Signaling

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Asif Pathan ◽  
Talha Farid ◽  
Abdur Rahman Khan ◽  
Marjan Nasr ◽  
Marcin Wysoczynski ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Extracellular Vesicles ◽  
Embryonic Stem ◽  
Tube Formation ◽  
Right Atrial ◽  
Boyden Chamber ◽  
Human Umbilical Cord ◽  
Angiogenic Activity ◽  
Cell Based Therapy

Cell-based therapy is considered a promising approach to treat the damaged heart due to myocardial infarction. Although the mechanisms for their beneficial action are not yet clear, exosome/extracellular vesicles (EVs) secreted by these cells may be involved in their reparative paracrine signaling. Previous studies have suggested that EVs isolated from several cell types (e.g. cardiosphere-derived cells, embryonic stem cell, CD34+ stem cells) induce angiogenic activity both in vitro and in vivo . Here, we investigated whether EVs secreted by adult human cardiac mesenchymal cells (hCMCs) exhibit pro-angiogenic activity, and if so, what signaling molecules are involved in this process. hCMCs were isolated from right atrial appendage of patients undergoing cardiac procedures and were characterized by the expression of classical mesenchymal markers- CD29 (99.1%), CD73 (99.0%), CD90 (20.4%), CD105 (99.3%), CD 31 (16.8%), CD34 (0.9%) and CD45 (0.1%). EVs isolated from serum-free 24-hour hCMC conditioned media using PEG4000-based precipitation technique exhibited two distinct population of particles with size range of 10-60nm and 100-500nm in diameter; expressed characteristic exosomal markers- CD63, HSP70, Flotillin-1 and were negative for cellular organelle markers- calreticulin (ER and apoptotic bodies), prohibitin (mitochondria), GM130 (Golgi), Lamin B (nuclear protein), β-actin (cytoskeleton) and PMP70 (peroxisomes) as determined by immunoblotting. In vitro assays revealed that hCMC EVs promote human umbilical cord endothelial cells (HUVECs) proliferation, transwell migration in Boyden chamber and tube formation on Matrigel, indicative of enhanced angiogenesis. Angiogenic proteomic array identified that angiopoietin-1 (ANG-1) and angiopoietin-2 (ANG-2) proteins are highly enriched in EVs secreted by hCMCs. Furthermore, hCMC EV mediated HUVEC migration and tube formation was inhibited by TIE2 kinase inhibitor. Overall, these findings suggest that ANG-1 and ANG-2 are the key component of hCMC secreted EVs and they promote angiogenesis by activating TIE2 receptor in endothelial cells.

Abstract P211: N-Acetyl-Seryl-Aspartyl-Lysyl-Proline (Ac-SDKP) Promotes Tube Formation in Human Coronary Artery Endothelial Cells

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Ginette Bordcoch ◽  
Pablo Nakagawa ◽  
Cesar A Romero ◽  
Oscar A Romero
Keyword(s):  
Endothelial Cells ◽  
Coronary Artery ◽  
Capillary Tube ◽  
Tube Formation ◽  
Endothelial Cell Migration ◽  
Tube Length ◽  
Human Coronary Artery ◽  
Double Phase ◽  
Angiogenic Effect

Ac-SDKP is an endogenous peptide with anti-inflammation and anti-fibrotic effects in hypertensive and cardiovascular diseases. It is cleaved from Thymosin β4 (Tβ4) and hydrolyzed by angiotensin converting enzyme (ACE). Ac-SDKP plasma concentration increases after treatment with ACE inhibitors (ACEi) and some of the beneficial effects of ACEi treatment has been ascribed to Ac-SDKP. Ac-SDKP is a mediator of angiogenesis in in-vitro and in-vivo animal models. Ac-SDKP stimulates rodents derived immortalized aortic endothelial cells migration and capillary-like structures formation (tube formation). Similarly, Ac-SDKP increases capillary density after myocardial infarction in rats. The mechanism related to angiogenesis induced by Ac-SDKP is not known. Tβ4 (Ac-SDKP precursor) promotes endothelial cell migration and angiogenesis by the activation of the VEGF/AKT pathway. Our objective is to evaluate the Ac-SDKP pro-angiogenic effect in Human Coronary Artery Endothelial Cells (HCAEC) and the mechanism that regulates the angiogenic effect of Ac-SDKP. HCAEC do not produce VEGF, thus we hypothesize that Ac-SDKP increases VEGF expression in fibroblasts and that indirectly could promote capillary tube formation in endothelial cells. We used primary culture of rat cardiac fibroblast (RCF) and we treated these cells with 10nM Ac-SDKP for 24 hours. VEGF concentration in cell supernatant was measured by ELISA. Cells were starved without serum overnight before the Ac-SDKP treatment. For capillary tube formation assay, HCAEC cells were seeded into matrigel and incubated in presence of 10nM Ac-SDKP for 12 hours, pictures were taken by double phase contrast microscope and tube length was quantified with image J software and the results were expressed as percentage of control. After Ac-SDKP treatment, VEGF concentration did not increase in the supernatant of RCF (control: 0.12±0.07 vs. Ac-SDKP: 0.14±0.09 mg/ml; p=0.7). However, Ac-SDKP treatment induced the development of tube formation in HCAECs by 7±2% respect to control (p=0.037). We conclude that Ac-SDKP induces capillary tube formation not only in rodent but also in human derived endothelial cells. The mechanism by which Ac-SDKP promotes tube formation in HCAECs is still unknown.

Abstract 470: Recording Cell Migration Dynamics in Mouse Tissues With Cells Secreting Fluorescence Protein-tagged Collagen

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Zhongming Chen
Keyword(s):  
Cell Migration ◽  
Cell Lines ◽  
Wild Type Mouse ◽  
Cardiac Progenitor Cells ◽  
Wild Type ◽  
Mouse Tissues ◽  
Migration Dynamics ◽  
Fluorescence Protein

Background: Cell migration is an important step involved in heart regeneration and many cardiovascular diseases. However, cell migration dynamics in vivo is poorly understood due to the challenges from mammal hearts, which are opaque and fast beating, and thus individual cardiac cells cannot be imaged or tracked. Aims: In this study, cell migration dynamics in the heart is recorded with a novel strategy, in which fluorescence protein-tagged collagen is secreted from cells and deposited into extracellular matrix, forming visible trails when cells are moving in tissues. As a proof-of-concept, transplanted migration dynamics of cardiac progenitor cells in mouse hearts were investaged. Methods: Stable cell lines expressing mCherry-tagged type I collagen were generated from isolated cardiac progenitor cells, ABCG2 + CD45 - CD31 - cells (side populations), or c-kit + CD45 - CD31 - cells (c-kit + CPCs). The cell migration dynamics were monitored and measured based on the cell trails after cell transplantation into mouse tissues. Results: The stable cell lines form red cell trails both in vitro and in vivo (Fig. 1A & 1B, Green: GFP; Red: mCherry-collagen I, Blue: DAPI, bar: 50 microns). In culture dishes, the cells form visible cell trails of fluorescence protein. The cell moving directions are random, with a speed of 288 +/- 79 microns/day (side populations, n=3) or 143 +/-37 microns/day (c-kit + CPCs, n=3). After transplantation into wild-type mouse hearts, the cells form highly tortuous trails along the gaps between the heart muscle fibers. Angle between a cell trail and a muscle fiber is 16+/-16 degree (n=3). Side populations migrate twice as fast as c-kit+ CPCs in the heart (16.0 +/-8.7 microns/day vs. 8.1+/-0.0 microns/day, n=3, respectively), 18 time slower than the respective speeds in vitro . Additionally, side populations migrate significantly faster in the heart than in the skeletal muscles (26.4+/-5.8 microns/day, n=3). The side populations move significantly faster in immunodeficient mouse hearts (36.7+/-13.3 microns/day, n=3, typically used for studying cell therapies) than in wild-type mouse hearts. Conclusion: For the first time, cell migration dynamics in living hearts is monitored and examined with genetically modified cell lines. This study may greatly advance the fields of cardiovascular biology.

scholarly journals Serotonin 5-HT2C Receptor Cys23Ser Single Nucleotide Polymorphism Associates with Receptor Function and Localization In Vitro

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Michelle A. Land ◽  
Holly L. Chapman ◽  
Brionna D. Davis-Reyes ◽  
Daniel E. Felsing ◽  
John A. Allen ◽  
...  
Keyword(s):  
Single Nucleotide Polymorphism ◽  
Subcellular Localization ◽  
Cell Lines ◽  
Intracellular Signaling ◽  
Calcium Release ◽  
Wild Type ◽  
Nucleotide Polymorphism ◽  
Single Nucleotide ◽  
Recycling Pathway

Abstract A non-synonymous single nucleotide polymorphism of the human serotonin 5-HT2C receptor (5-HT2CR) gene that converts a cysteine to a serine at amino acid codon 23 (Cys23Ser) appears to impact 5-HT2CR pharmacology at a cellular and systems level. We hypothesized that the Cys23Ser alters 5-HT2CR intracellular signaling via changes in subcellular localization in vitro. Using cell lines stably expressing the wild-type Cys23 or the Ser23 variant, we show that 5-HT evokes intracellular calcium release with decreased potency and peak response in the Ser23 versus the Cys23 cell lines. Biochemical analyses demonstrated lower Ser23 5-HT2CR plasma membrane localization versus the Cys23 5-HT2CR. Subcellular localization studies demonstrated O-linked glycosylation of the Ser23 variant, but not the wild-type Cys23, may be a post-translational mechanism which alters its localization within the Golgi apparatus. Further, both the Cys23 and Ser23 5-HT2CR are present in the recycling pathway with the Ser23 variant having decreased colocalization with the early endosome versus the Cys23 allele. Agonism of the 5-HT2CR causes the Ser23 variant to exit the recycling pathway with no effect on the Cys23 allele. Taken together, the Ser23 variant exhibits a distinct pharmacological and subcellular localization profile versus the wild-type Cys23 allele, which could impact aspects of receptor pharmacology in individuals expressing the Cys23Ser SNP.

Aberrant fibrin formation and cross-linking of fibrinogen Nieuwegein, a variant with a shortened Aα-chain, alters endothelial capillary tube formation

Blood ◽  
2001 ◽  
Vol 97 (4) ◽  
pp. 973-980 ◽  
Author(s):  
Annemie Collen ◽  
Annemarie Maas ◽  
Teake Kooistra ◽  
Florea Lupu ◽  
Jos Grimbergen ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Capillary Tube ◽  
Stop Codon ◽  
Tissue Transglutaminase ◽  
Tube Formation ◽  
Factor Xiiia ◽  
Cross Linking ◽  
Molecular Abnormalities ◽  
Fibrin Network

Abstract A congenital dysfibrinogenemia, fibrinogenNieuwegein, was discovered in a young man without any thromboembolic complications or bleeding. A homozygous insertion of a single nucleotide (C) in codon Aα 453 (Pro) introduced a stop codon at position 454, which resulted in the deletion of the carboxyl-terminal segment Aα 454-610. The ensuing unpaired cysteine at Aα 442 generated fibrinogen-albumin complexes of different molecular weights. The molecular abnormalities of fibrinogenNieuwegein led to a delayed clotting and a fibrin network with a low turbidity. Electron microscopy confirmed that thin fibrin bundles were organized in a fine network. The use of fibrinogenNieuwegein-derived fibrin (fibrinNieuwegein) in an in vitro angiogenesis model resulted in a strong reduction of tube formation. The ingrowth of human microvascular endothelial cells (hMVEC) was independent of αvβ3, indicating that the reduced ingrowth is not due to the absence of the RGD-adhesion site at position Aα 572-574. Rather, the altered structure of fibrinNieuwegeinis the cause, since partial normalization of the fibrin network by lowering the pH during polymerization resulted in an increased tube formation. Whereas factor XIIIa further decreased the ingrowth of hMVEC in fibrinNieuwegein, tissue transglutaminase (TG), which is released in areas of vessel injury, did not. This is in line with the absence of the cross-linking site for TG in the α-chains of fibrinogenNieuwegein. In conclusion, this newly discovered congenital dysfibrinogenemia has a delayed clotting time and leads to the formation of an altered fibrin structure, which could not be cross-linked by TG and which is less supportive for ingrowth of endothelial cells.

scholarly journals TWIST1 Heterodimerization with E12 Requires Coordinated Protein Phosphorylation to Regulate Periostin Expression

Cancers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1392
Author(s):  
Svetlana A. Mikheeva ◽  
Nathan D. Camp ◽  
Lei Huang ◽  
Antrix Jain ◽  
Sung Yun Jung ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Cell Invasion ◽  
Glioma Cells ◽  
Therapeutic Strategies ◽  
Bhlh Transcription Factor ◽  
Phosphorylation Sites ◽  
Wild Type ◽  
Dismal Prognosis ◽  
Adjacent Brain

Diffuse invasion into adjacent brain matter by glioblastoma (GBM) is largely responsible for their dismal prognosis. Previously, we showed that the TWIST1 (TW) bHLH transcription factor and its regulated gene periostin (POSTN) promote invasive phenotypes of GBM cells. Since TW functional effects are regulated by phosphorylation and dimerization, we investigated how phosphorylation of serine 68 in TW regulates TW dimerization, POSTN expression, and invasion in glioma cells. Compared with wild-type TW, the hypophosphorylation mutant, TW(S68A), impaired TW heterodimerization with the E12 bHLH transcription factor and cell invasion in vitro but had no effect on TW homodimerization. Overexpression of TW:E12 forced dimerization constructs (FDCs) increased glioma cell invasion and upregulated pro-invasive proteins, including POSTN, in concert with cytoskeletal reorganization. By contrast, TW:TW homodimer FDCs inhibited POSTN expression and cell invasion in vitro. Further, phosphorylation of analogous PXSP phosphorylation sites in TW:E12 FDCs (TW S68 and E12 S139) coordinately regulated POSTN and PDGFRa mRNA expression. These results suggested that TW regulates pro-invasive phenotypes in part through coordinated phosphorylation events in TW and E12 that promote heterodimer formation and regulate downstream targets. This new mechanistic understanding provides potential therapeutic strategies to inhibit TW-POSTN signaling in GBM and other cancers.

scholarly journals Unstable Spinocerebellar Ataxia Type 10 (ATTCT)·(AGAAT) Repeats Are Associated with Aberrant Replication at the ATX10 Locus and Replication Origin-Dependent Expansion at an Ectopic Site in Human Cells

2007 ◽  
Vol 27 (22) ◽  
pp. 7828-7838 ◽  
Author(s):  
Guoqi Liu ◽  
John J. Bissler ◽  
Richard R. Sinden ◽  
Michael Leffak
Keyword(s):  
Molecular Mechanism ◽  
Cell Lines ◽  
Spinocerebellar Ataxia ◽  
Replication Origin ◽  
Spinocerebellar Ataxia Type ◽  
Dna Unwinding ◽  
Wild Type ◽  
Normal Length ◽  
Population Doublings

ABSTRACT Spinocerebellar ataxia type 10 (SCA10) is associated with expansion of (ATTCT) n repeats (where n is the number of repeats) within the ataxin 10 (ATX10/E46L) gene. The demonstration that (ATTCT) n tracts can act as DNA unwinding elements (DUEs) in vitro has suggested that aberrant replication origin activity occurs at expanded (ATTCT) n tracts and may lead to their instability. Here, we confirm these predictions. The wild-type ATX10 locus displays inefficient origin activity, but origin activity is elevated at the expanded ATX10 loci in patient-derived cells. To test whether (ATTCT) n tracts can potentiate origin activity, cell lines were constructed that contain ectopic copies of the c-myc replicator in which the essential DUE was replaced by ATX10 DUEs with (ATTCT) n . ATX10 DUEs containing (ATTCT)27 or (ATTCT)48, but not (ATTCT)8 or (ATTCT)13, could substitute functionally for the c-myc DUE, but (ATTCT)48 could not act as an autonomous replicator. Significantly, chimeric c-myc replicators containing ATX10 DUEs displayed length-dependent (ATTCT) n instability. By 250 population doublings, dramatic two- and fourfold length expansions were observed for (ATTCT)27 and (ATTCT)48 but not for (ATTCT)8 or (ATTCT)13. These results implicate replication origin activity as one molecular mechanism associated with the instability of (ATTCT) n tracts that are longer than normal length.

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