Dataset Information

Fitness cost of LINE-1 (L1) activity in humans.

ABSTRACT: The self-replicating LINE-1 (L1) retrotransposon family is the dominant retrotransposon family in mammals and has generated 30-40% of their genomes. Active L1 families are present in modern mammals but the important question of whether these currently active families affect the genetic fitness of their hosts has not been addressed. This issue is of particular relevance to humans as Homo sapiens contains the active L1 Ta1 subfamily of the human specific Ta (L1Pa1) L1 family. Although DNA insertions generated by the Ta1 subfamily can cause genetic defects in current humans, these are relatively rare, and it is not known whether Ta1-generated inserts or any other property of Ta1 elements have been sufficiently deleterious to reduce the fitness of humans. Here we show that full-length (FL) Ta1 elements, but not the truncated Ta1 elements or SINE (Alu) insertions generated by Ta1 activity, were subject to negative selection. Thus, one or more properties unique to FL L1 elements constitute a genetic burden for modern humans. We also found that the FL Ta1 elements became more deleterious as the expansion of Ta1 has proceeded. Because this expansion is ongoing, the Ta1 subfamily almost certainly continues to decrease the fitness of modern humans.

SUBMITTER: Boissinot S

PROVIDER: S-EPMC1480451 | biostudies-literature | 2006 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Fitness cost of LINE-1 (L1) activity in humans.

Boissinot Stephane S Davis Jerel J Entezam Ali A Petrov Dimitri D Furano Anthony V AV

Proceedings of the National Academy of Sciences of the United States of America 20060609 25

The self-replicating LINE-1 (L1) retrotransposon family is the dominant retrotransposon family in mammals and has generated 30-40% of their genomes. Active L1 families are present in modern mammals but the important question of whether these currently active families affect the genetic fitness of their hosts has not been addressed. This issue is of particular relevance to humans as Homo sapiens contains the active L1 Ta1 subfamily of the human specific Ta (L1Pa1) L1 family. Although DNA insertio ...[more]

PMID: 16766655

Similar Datasets

Project description:Driven essentially by random genetic drift, subfunctionalization has been identified as a possible non-adaptive mechanism for the retention of duplicate genes in small-population species, where widespread deleterious mutations are likely to cause complementary loss of subfunctions across gene copies. Through subfunctionalization, duplicates become indispensable to maintain the functional requirements of the ancestral locus. Yet, gene duplication produces a dosage imbalance in the encoded proteins and thus, as investigated in this paper, subfunctionalization must be subject to the selective forces arising from the fitness bottleneck introduced by the duplication event.We show that, while arising from random drift, subfunctionalization must be inescapably subject to selective forces, since the diversification of expression patterns across paralogs mitigates duplication-related dosage imbalances in the concentrations of encoded proteins. Dosage imbalance effects become paramount when proteins rely on obligatory associations to maintain their structural integrity, and are expected to be weaker when protein complexation is ephemeral or adventitious. To establish the buffering effect of subfunctionalization on selection pressure, we determine the packing quality of encoded proteins, an established indicator of dosage sensitivity, and correlate this parameter with the extent of paralog segregation in humans, using species with larger population -and more efficient selection- as controls.Recognizing the role of subfunctionalization as a dosage-imbalance buffer in gene duplication events enabled us to reconcile its mechanistic nonadaptive origin with its adaptive role as an enabler of the evolution of genetic redundancy. This constructive role was established in this paper by proving the following assertion: If subfunctionalization is indeed adaptive, its effect on paralog segregation should scale with the dosage sensitivity of the duplicated genes. Thus, subfunctionalization becomes adaptive in response to the selection forces arising from the fitness bottleneck imposed by gene duplication.

Project description:ObjectiveOur previous economic assessment found that nivolumab was not cost-effective for Chinese patients with advanced non-small cell lung cancer (NSCLC) and without EGFR mutations or ALK translocations, when compared with the standard second-line drug docetaxel. However, a greater survival benefit with nivolumab was observed for patients with 1% or greater tumor programmed death ligand 1 (PD-L1) expression. In view of this, we designed the present analysis to explore whether it is cost-effective to use the PD-L1 test to guide second-line nivolumab treatment in China.Material and methodsA Markov model was established to project the lifetime costs and quality-adjusted life-years (QALYs) of three second-line treatment strategies: nivolumab and docetaxel (strategies without a PD-L1 test) and PD-L1 test-based strategy. Deterministic and probabilistic sensitivity analyses were performed to examine the robustness of our results. Additional price reduction and willingness-to-pay (WTP) threshold scenario analyses were performed to explore the impact of economic and health policies with Chinese characteristics on our results.ResultsThe PD-L1 test-based strategy costs approximately CNY 194,607 (USD 28,210) or more and yielded an additional 0.27 QALYs compared to the docetaxel strategy without a PD-L1 test, equating an incremental cost-effectiveness ratio (ICER) of CNY 731,089 (USD 105,978)/QALY. Deterministic sensitivity analyses showed that the price of nivolumab was the strongest source of variation in the ICERs. Probability sensitivity analysis showed that the probability for the PD-L1 test-based strategy being cost-effective increases with the increase of WTP thresholds.ConclusionFrom the perspective of the Chinese healthcare system, using a PD-L1 test to guide second-line nivolumab treatment was not cost-effective. The National Healthcare Security Administration negotiation on the price reduction of nivolumab was found to be the most effective action to improve its cost-effectiveness in China.

Dataset Information

Fitness cost of LINE-1 (L1) activity in humans.

Publications

Fitness cost of LINE-1 (L1) activity in humans.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure