Human telomeric repeat binding factors TRF1 and TRF2 along with TIN2 form the core of the shelterin complex that protects chromosome ends against unwanted end-joining and DNA repair. We applied a single-molecule approach to assess TRF1-TIN2-TRF2 complex formation in solution at physiological conditions. Fluorescence cross-correlation spectroscopy was used to describe the complex assembly by analyzing how coincident fluctuations of differently labeled TRF1 and TRF2 correlate when they move together through the confocal volume of the microscope. We observed, at the single-molecule level, that TRF1 effectively substitutes TRF2 on TIN2. We assessed also the effect of another telomeric factor TPP1 that recruits telomerase to telomeres. We found that TPP1 upon binding to TIN2 induces changes that expand TIN2 binding capacity, such that TIN2 can accommodate both TRF1 and TRF2 simultaneously. We suggest a molecular model that explains why TPP1 is essential for the stable formation of TRF1-TIN2-TRF2 core complex.

• MeSH
• DNA vazebné proteiny chemie   metabolismus   MeSH
• lidé MeSH
• molekulární modely MeSH
• multimerizace proteinu MeSH
• protein TRF1 genetika   metabolismus   MeSH
• protein TRF2 genetika   metabolismus   MeSH
• proteinové domény MeSH
• proteiny vázající telomery genetika   metabolismus   MeSH
• telomerasa metabolismus   MeSH
• telomery metabolismus   MeSH
• vazba proteinů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The semiconservative replication of telomeres is facilitated by the shelterin component TRF1. Without TRF1, replication forks stall in the telomeric repeats, leading to ATR kinase signaling upon S-phase progression, fragile metaphase telomeres that resemble the common fragile sites (CFSs), and the association of sister telomeres. In contrast, TRF1 does not contribute significantly to the end protection functions of shelterin. We addressed the mechanism of TRF1 action using mouse conditional knockouts of BLM, TRF1, TPP1, and Rap1 in combination with expression of TRF1 and TIN2 mutants. The data establish that TRF1 binds BLM to facilitate lagging but not leading strand telomeric DNA synthesis. As the template for lagging strand telomeric DNA synthesis is the TTAGGG repeat strand, TRF1-bound BLM is likely required to remove secondary structures formed by these sequences. In addition, the data establish that TRF1 deploys TIN2 and the TPP1/POT1 heterodimers in shelterin to prevent ATR during telomere replication and repress the accompanying sister telomere associations. Thus, TRF1 uses two distinct mechanisms to promote replication of telomeric DNA and circumvent the consequences of replication stress. These data are relevant to the expression of CFSs and provide insights into TIN2, which is compromised in dyskeratosis congenita (DC) and related disorders.

• MeSH
• aktivace enzymů MeSH
• aminopeptidasy genetika   metabolismus   MeSH
• ATM protein metabolismus   MeSH
• dipeptidylpeptidasy a tripeptidylpeptidasy genetika   metabolismus   MeSH
• DNA vazebné proteiny metabolismus   MeSH
• genový knockout MeSH
• helikasy RecQ genetika   metabolismus   MeSH
• kultivované buňky MeSH
• mikrosatelitní repetice genetika   MeSH
• mutace MeSH
• protein TRF1 genetika   metabolismus   MeSH
• proteiny vázající telomery genetika   metabolismus   MeSH
• replikace DNA genetika   MeSH
• serinové proteasy genetika   metabolismus   MeSH
• signální transdukce MeSH
• telomery genetika   MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

Telomeres are specialized chromatin structures that are situated at the end of linear chromosomes and play an important role in cell senescence and immortalization. Here, we investigated whether changes in histone signature influence the nuclear arrangement and positioning of telomeres. Analysis of mouse embryonic fibroblasts revealed that telomeres were organized into specific clusters that partially associated with centromeric clusters. This nuclear arrangement was influenced by deficiency of the histone methyltransferase SUV39h, LMNA deficiency, and the histone deacetylase inhibitor Trichostatin A (TSA). Similarly, nuclear radial distributions of telomeric clusters were preferentially influenced by TSA, which caused relocation of telomeres closer to the nuclear center. Telomeres also co-localized with promyelocytic leukemia bodies (PML). This association was increased by SUV39h deficiency and decreased by LMNA deficiency. These differences could be explained by differing levels of the telomerase subunit, TERT, in SUV39h- and LMNA-deficient fibroblasts. Taken together, our data show that SUV39h and A-type lamins likely play a key role in telomere maintenance and telomere nuclear architecture.

• MeSH
• DNA vazebné proteiny metabolismus   MeSH
• epigeneze genetická MeSH
• fibroblasty metabolismus   MeSH
• genová přestavba MeSH
• intranukleární inkluzní tělíska metabolismus   MeSH
• lamin typ A metabolismus   MeSH
• lidé MeSH
• methyltransferasy metabolismus   MeSH
• myši MeSH
• protein TRF1 metabolismus   MeSH
• průtoková cytometrie MeSH
• rap1 proteiny vázající GTP metabolismus   MeSH
• represorové proteiny metabolismus   MeSH
• telomerasa metabolismus   MeSH
• telomery genetika   metabolismus   MeSH
• transport proteinů MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

This study combines mRNA and protein analysis using cDNA and antibody microarray techniques, respectively. These create a novel, integrated perspective into cellular molecular profiles. The aims of this study were to establish a reliable way of integrating these two approaches in order to obtain complex molecular profiles of the cell and to find suitable methods to normalize the data obtained using these approaches.

Antibody microarray and cDNA microarray techniques were used to study expression alterations in HL-60 cells that were differentiated into granulocytes using all-trans retinoic acid (ATRA). We selected this model to evaluate this combined profiling technique because the expression levels of most of the mRNA and protein species in these cells are not altered; therefore it is easier to track and define those species that are changed. The proteins whose levels were altered included c-myc, c-jun, Pyk2, FAK, PKC, TRF1, NF-kappaB and certain caspase types. These proteins are involved in apoptosis and hematopoietic differentiation pathways, and some have also been reported to have oncogenic potential. We compared the results obtained using the two methods, verified them by immunoblotting analysis, and devised normalization approaches.

This is one of the first demonstrations that a combination of antibody microarray and cDNA microarray techniques is required for complex molecular profiling of cells based on multiple parameters. This approach allows a more detailed molecular phenotype of the given sample to be obtained. The results obtained using a combination of the two profiling methods are consistent with those from previous studies that used more traditional methods.

• MeSH
• čipová analýza proteinů MeSH
• financování organizované MeSH
• fokální adhezní kinasa 2 analýza   MeSH
• geny myc MeSH
• HL-60 buňky MeSH
• lidé MeSH
• messenger RNA analýza   MeSH
• protein TRF1 analýza   MeSH
• sekvenční analýza hybridizací s uspořádaným souborem oligonukleotidů MeSH
• tretinoin farmakologie   MeSH
• Check Tag
• lidé MeSH