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Competitive formation of homocircuit [3]rotaxanes in synthetically useful yields in the bipyridine-mediated active template CuAAC reaction.

ABSTRACT: We recently identified competitive formation of doubly interlocked [3]rotaxanes as the origin of the non-linear variation in yield of [2]rotaxane with macrocycle size in the bipyridine-mediated AT-CuAAC reaction. Selection of reaction conditions gave [2]rotaxanes in essentially quantitative yield in all cases and hard to access doubly threaded [3]rotaxanes in up to 50% yield in a single, four component coupling. Based on the effect of macrocycle structure on the reaction outcome we propose a detailed mechanism of [3]rotaxane formation.

SUBMITTER: Neal EA

PROVIDER: S-EPMC5645920 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Diastereoselective synthesis of [1]rotaxanes <i>via</i> an active metal template strategy.

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High yielding synthesis of 2,2'-bipyridine macrocycles, versatile intermediates in the synthesis of rotaxanes.

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BTG1 mutation yields super-competitive B cells primed for malignant transformation

Project description:Mutations in the BTG1 tumor suppressor gene are exclusive to germinal center (GC)-derived B cell lymphomas and associate with low clinical outcome. To elucidate the effect of BTG1 mutations in mature B cells, we generated a mouse model for the conditional expression of mutant Btg1 Unlike conventional lymphoma oncogenes, mutated Btg1 expression in B cells did not induce GC hyperplasia. However, placing mutant and wild-type GC B cells in direct competition revealed that mutant Btg1 provides a massive advantage during the GC reaction. Furthermore, mutant Btg1 accelerates and dramatically increases the aggressiveness of BCL2-driven lymphomas in vivo. NGS, cellular and molecular profiling showed activation of Myc and mTORC1 anabolic programs in Btg1 mutant GC B cells, murine lymphomas and patient DLBCLs. These programs characterize T cell-selected GC B cells that enter a growth phase prior to clonal burst. We find that mutant Btg1 sensitizes GC B cells to T cell signals, resulting in a lower threshold to Myc activation, through mRNA translational biochemical mechanisms. Together, we link recurrent mutations of BTG1 to a massive fitness gain of GC B cells that confers an agressive and invasive phenotype to B cell lymphomas in vivo and associate with low clinical outcome in patients with agressive DLBCL. This work reveals a fine-tuned metabolic regulatory network that controls normal GC development and can be hijacked by lymphoma cells during disease progression. These findings have implications for fitness processes and natural selection at a broad level by providing fundamental insight into the power of subtle biochemical shifts to enhance biological fitness of cells.

2023-01-24 | GSE167786 | GEO

Selective Monofunctionalization Enabled by Reaction-History-Dependent Communication in Catalytic Rotaxanes.

Project description:Selective monofunctionalization of substrates with distant, yet equally reactive functional groups is difficult to achieve, as it requires the second functional group to selectively modulate its reactivity once the first functional group has reacted. We now show that mechanically interlocked catalytic rings can effectively regulate the reactivity of stoppering groups in rotaxanes over a distance of about 2 nm. Our mechanism of communication is enabled by a unique interlocked design, which effectively removes the catalytic rings from the substrates by fast dethreading as soon as the first reaction has taken place. Our method not only led to a rare example of selective monofunctionalization, but also to a "molecular if function". Overall, the study presents a way to get distant functional groups to communicate with each other in a reaction-history-dependent manner by creating linkers that can ultimately perform logical operations at the molecular level.

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