Ionic Liquid Immobilized Organocatalysts for Asymmetric Reactions in Aqueous Media

Qiao, Yupu; Headley, Allan D.

doi:10.3390/catal3030709

Cited by 40 publications

(17 citation statements)

References 94 publications

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“…These findings fit with the reported data on telomerase activity in gliomas which is considerably higher in GBM (50-89 %) and oligodendrogliomas (75-100 %), than in astrocytomas (0-45 %) [49,67,106]. The low frequency of TERT promoter mutations and telomerase activity in grades II and III astrocytomas can be explained by the high prevalence of ATRX mutations, one of the most frequent mutations in this type of glioma [56]. It is known that ATRX mutations trigger ALT in astrocytoma cells and it has been shown that this alternative mechanism is frequently activated in astrocytomas, allowing telomere maintenance without the need for telomerase reactivation [48].…”

Section: Telomerase Promoter Mutations In Bladder Carcinomassupporting

confidence: 80%

Telomerase promoter mutations in cancer: an emerging molecular biomarker?

et al. 2014

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Cell immortalization has been considered for a long time as a classic hallmark of cancer cells. Besides telomerase reactivation, such immortalization could be due to telomere maintenance through the "alternative mechanism of telomere lengthening" (ALT) but the mechanisms underlying both forms of reactivation remained elusive. Mutations in the coding region of telomerase gene are very rare in the cancer setting, despite being associated with some degenerative diseases. Recently, mutations in telomerase (TERT) gene promoter were found in sporadic and familial melanoma and subsequently in several cancer models, notably in gliomas, thyroid cancer and bladder cancer. The importance of these findings has been reinforced by the association of TERT mutations in some cancer types with tumour aggressiveness and patient survival. In the first part of this review, we summarize the data on the biology of telomeres and telomerase, available methodological approaches and nonneoplastic diseases associated with telomere dysfunction. In the second part, we review the information on telomerase expression and genetic alterations in the most relevant types of cancer (skin, thyroid, bladder and central nervous system) on record, and discuss the value of telomerase as a new biomarker with impact on the prognosis and survival of the patients and as a putative therapeutic target.

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Section: Telomerase Promoter Mutations In Bladder Carcinomassupporting

confidence: 80%

Telomerase promoter mutations in cancer: an emerging molecular biomarker?

et al. 2014

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“…The latter possibly resulted from impaired transcription, as RNAP II levels were also severely depressed following ATRX inactivation. Previous findings, mainly from clinical studies, have pointed to the simultaneous occurrence of a mutation in ATRX and of the telomeraseindependent ALT pathway in several types of tumors (10,11,(20)(21)(22)(23). This list is not exhaustive, as other, more recent studies have confirmed these early findings.…”

Section: Discussionsupporting

confidence: 55%

“…Thus, in several clinical studies, mutations in ATRX were found to be tightly associated with the ALT pathway in various types of tumors (10,11,(20)(21)(22)(23). This correlation has also been observed in cultured cells (24,25).…”

Section: Atrx Localizes To Subtelomeric Regions Of Human Glioma Cellsmentioning

confidence: 60%

Genetic Inactivation of ATRX Leads to a Decrease in the Amount of Telomeric Cohesin and Level of Telomere Transcription in Human Glioma Cells

Eid

Demattei

Episkopou

et al. 2015

Molecular and Cellular Biology

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cMutations in ATRX (alpha thalassemia/mental retardation syndrome X-linked), a chromatin-remodeling protein, are associated with the telomerase-independent ALT (alternative lengthening of telomeres) pathway of telomere maintenance in several types of cancer, including human gliomas. In telomerase-positive glioma cells, we found by immunofluorescence that ATRX localized not far from the chromosome ends but not exactly at the telomere termini. Chromatin immunoprecipitation (ChIP) experiments confirmed a subtelomeric localization for ATRX, yet short hairpin RNA (shRNA)-mediated genetic inactivation of ATRX failed to trigger the ALT pathway. Cohesin has been recently shown to be part of telomeric chromatin. Here, using ChIP, we showed that genetic inactivation of ATRX provoked diminution in the amount of cohesin in subtelomeric regions of telomerasepositive glioma cells. Inactivation of ATRX also led to diminution in the amount of TERRAs, noncoding RNAs resulting from transcription of telomeric DNA, as well as to a decrease in RNA polymerase II (RNAP II) levels at the telomeres. Our data suggest that ATRX might establish functional interactions with cohesin on telomeric chromatin in order to control TERRA levels and that one or the other or both of these events might be relevant to the triggering of the ALT pathway in cancer cells that exhibit genetic inactivation of ATRX.T he linear chromosomes of eukaryotic organisms require particular protection at their extremities. Telomeres, which represent the ends of these chromosomes and contain repeated TGrich sequences that do not code for proteins, as well as proteins of the shelterin complex, are essential for this protection (1). Telomeres protect chromosome ends from DNA repair activities that reseal chromosome internal DNA breaks occurring during DNA damage (2). Telomere sequences naturally erode with ongoing cell divisions, due to intrinsic mechanisms associated with the fixed 5=-to-3= polarity of replication of the DNA of the genome. Below a certain threshold, shortened telomeres result in DNA damageinduced cell cycle arrest, which is the equivalent of replicative senescence in cultured cells.By limiting the replicative potential of cells, telomere length acts as a biological clock, and telomere erosion serves as a barrier against tumorigenesis in healthy tissue. Paradoxically, telomere erosion or telomere dysfunction also induces chromosomal instability and favors the emergence of tumors (3). However, following cancer initiation, tumor cells must overcome the telomere-controlled replicative-senescence barrier, and all have an absolute necessity to maintain functional telomeres in order to sustain continuous and unlimited cell proliferation. In around 85 to 90% of cancer types, this occurs through upregulation of telomerase, a reverse transcriptase with a built-in RNA template specialized in telomeric DNA replication that is naturally repressed in most somatic tissues (4). In the remaining 10 to 15% of cancer types, an alternative pathway called the ALT (alternativ...

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“…However, the immobilization of organocatalyst to ionic liquid systems gave catalyst which can be used either under organic or aqueous homogeneous conditions [101]. Hence, several functionalized ionic liquids have been attached to the pyrrolidine motif after quaternization of the pyrrolidineimidazole precursor.…”

Section: Aqueous Aldol Reactions With Supported Organocatalystsmentioning

confidence: 99%

Pursuing Chemical Efficiency by Using Supported Organocatalysts for Asymmetric Reactions under Aqueous Conditions

Guillena

Alonso²,

Baeza³

et al. 2015

COCAT

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Over the past decade, a great effort has been made by the chemical community to improve the efficiency and greenness of reactions. Merging the use of supported and recyclable organocatalysts and aqueous conditions to pursue this goal in the asymmetric synthesis of interesting enantioselective molecules lead to outstanding results in some cases. Progresses in this area also offer the possibility of having even more sustainable processes by implementing these reactions in the large scale production of chiral molecules using automated flow chemistry.

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Ionic Liquid Immobilized Organocatalysts for Asymmetric Reactions in Aqueous Media

Cited by 40 publications

References 94 publications

Telomerase promoter mutations in cancer: an emerging molecular biomarker?

Telomerase promoter mutations in cancer: an emerging molecular biomarker?

Genetic Inactivation of ATRX Leads to a Decrease in the Amount of Telomeric Cohesin and Level of Telomere Transcription in Human Glioma Cells

Pursuing Chemical Efficiency by Using Supported Organocatalysts for Asymmetric Reactions under Aqueous Conditions

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