Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 4 de 4
Filtrar
Mais filtros

Base de dados
Ano de publicação
Tipo de documento
País de afiliação
Intervalo de ano de publicação
1.
EMBO J ; 41(15): e109694, 2022 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-35694726

RESUMO

Naked mole rats (NMRs) are the longest-lived rodents yet their stem cell characteristics remain enigmatic. Here, we comprehensively mapped the NMR hematopoietic landscape and identified unique features likely contributing to longevity. Adult NMRs form red blood cells in spleen and marrow, which comprise a myeloid bias toward granulopoiesis together with decreased B-lymphopoiesis. Remarkably, youthful blood and marrow single-cell transcriptomes and cell compositions are largely maintained until at least middle age. Similar to primates, the primitive stem and progenitor cell (HSPC) compartment is marked by CD34 and THY1. Stem cell polarity is seen for Tubulin but not CDC42, and is not lost until 12 years of age. HSPC respiration rates are as low as in purified human stem cells, in concert with a strong expression signature for fatty acid metabolism. The pool of quiescent stem cells is higher than in mice, and the cell cycle of hematopoietic cells is prolonged. By characterizing the NMR hematopoietic landscape, we identified resilience phenotypes such as an increased quiescent HSPC compartment, absence of age-related decline, and neotenic traits likely geared toward longevity.


Assuntos
Envelhecimento , Ratos-Toupeira , Adulto , Envelhecimento/metabolismo , Animais , Hematopoese , Humanos , Camundongos , Pessoa de Meia-Idade , Ratos-Toupeira/genética , Ratos-Toupeira/metabolismo , Fenótipo , Células-Tronco
2.
Nucleic Acids Res ; 52(11): 6317-6332, 2024 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-38613387

RESUMO

Telomerase is the enzyme that lengthens telomeres and is tightly regulated by a variety of means to maintain genome integrity. Several DNA helicases function at telomeres, and we previously found that the Saccharomyces cerevisiae helicases Hrq1 and Pif1 directly regulate telomerase. To extend these findings, we are investigating the interplay between helicases, single-stranded DNA (ssDNA) binding proteins (ssBPs), and telomerase. The yeast ssBPs Cdc13 and RPA differentially affect Hrq1 and Pif1 helicase activity, and experiments to measure helicase disruption of Cdc13/ssDNA complexes instead revealed that Cdc13 can exchange between substrates. Although other ssBPs display dynamic binding, this was unexpected with Cdc13 due to the reported in vitro stability of the Cdc13/telomeric ssDNA complex. We found that the DNA exchange by Cdc13 occurs rapidly at physiological temperatures, requires telomeric repeat sequence DNA, and is affected by ssDNA length. Cdc13 truncations revealed that the low-affinity binding site (OB1), which is distal from the high-affinity binding site (OB3), is required for this intermolecular dynamic DNA exchange (DDE). We hypothesize that DDE by Cdc13 is the basis for how Cdc13 'moves' at telomeres to alternate between modes where it regulates telomerase activity and assists in telomere replication.


Assuntos
DNA Helicases , DNA de Cadeia Simples , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Proteínas de Ligação a Telômeros , Telômero , Sítios de Ligação , DNA Helicases/metabolismo , DNA Fúngico/metabolismo , DNA Fúngico/genética , DNA de Cadeia Simples/metabolismo , Proteínas de Ligação a DNA/metabolismo , Ligação Proteica , RecQ Helicases , Proteína de Replicação A/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Telomerase/metabolismo , Telômero/metabolismo , Proteínas de Ligação a Telômeros/metabolismo
3.
bioRxiv ; 2024 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-38105973

RESUMO

Telomerase is the enzyme that lengthens telomeres and is tightly regulated by a variety of means to maintain genome integrity. Several DNA helicases function at telomeres, and we previously found that the Saccharomyces cerevisiae helicases Hrq1 and Pif1 directly regulate telomerase. To extend these findings, we are investigating the interplay between helicases, single-stranded DNA (ssDNA) binding proteins (ssBPs), and telomerase. The yeast ssBPs Cdc13 and RPA differentially affect Hrq1 and Pif1 helicase activity, and experiments to measure helicase disruption of Cdc13/ssDNA complexes instead revealed that Cdc13 can exchange between substrates. Although other ssBPs display dynamic binding, this was unexpected with Cdc13 due to the reported in vitro stability of the Cdc13/telomeric ssDNA complex. We found that the DNA exchange by Cdc13 occurs rapidly at physiological temperatures, requires telomeric repeat sequence DNA, and is affected by ssDNA length. Cdc13 truncations revealed that the low-affinity binding site (OB1), which is distal from the high-affinity binding site (OB3), is required for this intermolecular dynamic DNA exchange (DDE). We hypothesize that DDE by Cdc13 is the basis for how Cdc13 'moves' at telomeres to alternate between modes where it regulates telomerase activity and assists in telomere replication.

4.
Methods Enzymol ; 673: 169-190, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35965006

RESUMO

DNA helicases are involved in nearly all facets of genome integrity, and in humans, mutations in helicase-encoding genes are often linked to diseases of genomic instability. Two highly studied and evolutionarily conserved helicase families are the PIF1 and RecQ helicases. Enzymes in these families have known roles in DNA replication, recombination, and repair, as well as telomere maintenance, DNA recombination, and transcription. Although genetics, structural biology, and a variety of other techniques have been used to study these helicases, ensemble analyses of their basic biochemical activities such as DNA binding, ATP hydrolysis, and DNA unwinding have made significant contributions to our understanding of their physiological roles. Here, we present general methods to generate recombinant proteins from both helicase families, as well as standard biochemical assays to investigate their activities on DNA.


Assuntos
Replicação do DNA , RecQ Helicases , DNA , DNA Helicases/genética , DNA Helicases/metabolismo , Reparo do DNA , Instabilidade Genômica , Humanos , RecQ Helicases/genética , RecQ Helicases/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA