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Early diagnosis of endometrial cancer (EC) is uncertain and women undergo preventive hysterectomy in cases where a non-invasive treatment can be used instead. To contribute to solving this challenge we investigated if early changes in the nuclear 3D telomere architecture during carcinoma development can be detected prior to the first morphological evidence of precancerous lesions. We utilized Pten heterozygous mice that develop progressive carcinoma in the endometrial tissue similar to EC development in women. We used telomere fluorescence in situ hybridization (FISH), 3D molecular imaging and analysis techniques on interphase nuclei of endometrial glandular epithelial cells to identify alterations in the 3D-telomere profile. We found that telomere dysfunction in Pten heterozygous mice is present already in endometrial simple hyperplasia lesions prior to detectable loss of PTEN protein expression and that the 3D telomere architecture has a specific signature that indicates early telomere dysfunction predictive for endometrial malignant transformation.

Early diagnosis of endometrial cancer (EC) is uncertain and women undergo preventive hysterectomy in cases where a non-invasive treatment can be used instead. To contribute to solving this challenge we investigated if early changes in the nuclear 3D telomere architecture during carcinoma development can be detected prior to the first morphological evidence of precancerous lesions. We utilized Pten heterozygous mice that develop progressive carcinoma in the endometrial tissue similar to EC development in women. We used telomere fluorescence in situ hybridization (FISH), 3D molecular imaging and analysis techniques on interphase nuclei of endometrial glandular epithelial cells to identify alterations in the 3D-telomere profile. We found that telomere dysfunction in Pten heterozygous mice is present already in endometrial simple hyperplasia lesions prior to detectable loss of PTEN protein expression and that the 3D telomere architecture has a specific signature that indicates early telomere dysfunction predictive for endometrial malignant transformation.

Thesis (Ph.D.) -- University of Texas Southwestern Medical Center at Dallas, 2006. / Partial embargo. Vita. Bibliography: 131-152.

Eines der charakteristischen Merkmale des Neuroblastoms stellt seine einzigartige biologische Heterogenität dar, die eine genaue Ausage des weiteren klinischen Verlaufes stark erschwert. Bestimmte prognostisch wirksame klinische, molekularbiologische und genetische Faktoren, wie zum Beispiel Alter bei Erstdiagnose, Tumorstadium, MYCN-Amplifikation und 1p Deletion, werden seit längerem zur Risikostratifizierung genutzt. Bereits in anderen Tumorerkrankungen konnte nun der Einfluß einer Telomerlängenveränderung auf das Gesamtüberleben von Patienten nachgewiesen werden. Telomere sichern die genomische Integrität und bestimmen maßgeblich die proliferative Kapazität jeder somatischen Zelle. Aktuelle Forschungsergebnisse legen die Vermutung nahe, dass Veränderungen der Telomerlänge auch in Neuroblastomen einen prognostischen Effekt auf das Gesamtüberleben haben. In diesem Kontext untersucht die vorliegende Arbeit den Zusammenhang zwischen Telomerlänge und Gesamtüberleben in 420 MYCN nicht-amplifizierten primären Neuroblastomen mit Erstdiagnosen von 1983-2001. Hierfür wurden die relativen Telomerlängen mithilfe einer neu etablierten monochromen multiplex q-RT-PCR ermittelt. Anschließend wurden diese sowohl mit ausgesuchten klinischen Variablen (Alter bei Erstdiagnose, Tumorstadium, Primärlokalisation des Tumors, Histologie, Geschlecht und Rezidivauftreten) korreliert als auch auf ihren Einfluß auf das Gesamt- und ereignisfreie Überleben untersucht. In Korrelation mit den klinischen Parametern konnte zwischen Alter bei Erstdiagnose und Telomerlänge ein eindeutiger Zusammenhang nachgewiesen werden. Je älter die Patienten bei Erstdiagnose, desto höher war sowohl der Anteil verlängerter Telomere als auch der extremer Telomerlängenveränderungen. Neuroblastome mit verlängerten Telomeren zeigten in der gleichen Altersgruppe ein verringertes Gesamtüberleben der betroffenen Patienten verglichen mit Neuroblastomen mit verkürzten Telomeren. Somit könnte eine Telomerlängenveränderung, insbesondere verlängerte Telomere, im klinischen Alltag als Hinweis auf einen prognostisch ungünstigen Verlauf genutzt werden.

ABSTRACT THE EFFECTS OF HIV DISEASE AND LIFESTYLE FACTORS ON CELLULAR AGING IN TRANSGENDER WOMEN by Scott Stephen Sohn Background: Telomeres are short tandem repeats of nucleotides at the ends of chromosomes. These specialized structures serve as caps on the end of the chromosomes, which protect DNA integrity. Telomeres get shorter each time a cell replicates, but the DNA remains intact as long as the telomere caps are a sufficient length. In time, telomeres become too short to protect DNA, which leads to cellular death. Previous research has shown that disease and negative lifestyle factors play a role in accelerated telomere attrition throughout the cellular life cycle. Objective: The purpose of this study was to determine if HIV infection and lifestyle factors in a transgender population living in Atlanta Georgia are associated with telomere length reduction. Participants/setting: This study is a secondary analysis of data provided by a Georgia State University study entitled “Telomere Length, Environmental Stressors and Health Related Outcomes among Transgender Women”. The study included 92 transgender women from Atlanta, Georgia with 49 reporting HIV infection. Two sources of data were collected, survey responses collected during face to face interviews and a saliva sample for DNA analysis. Statistical analysis: Frequency statistics were used to describe the sample population. A Mann Whitney U was used to evaluate telomere length using the T/S ratio by HIV status, by physical activity level (healthy active or low active) and by fruit and vegetable intake category (Don’t eat, 1-2 servings/day, 3-4 servings/day vs. >5 servings/day) in the total Population. Multiple regression analysis was used to examine the association between independent variables (activity level, body mass index, fruit and vegetable intake, hormone use, race, HIV status and age) and telomere length. Results: The majority of the population was Black (84%) with a median age of 33 years (range, 18 to 65 years). No significant association was observed between HIV infection and T/S ratio. The vast majority of the population reported low activity level and only 9% reported consuming >5 servings of fruits and vegetables daily. No significant association was found between fruit and vegetable intake or physical activity level and T/S ratio in this population. Conclusion: HIV infection, Fruit and vegetable intake, and physical activity were not found to impact telomere length in an urban population of transgender women. Future research is needed to further understand the mechanisms that impact telomere length throughout the cellular life cycle within the transgender population.

The age structure of populations is an important and often unresolved factor in ecology and wildlife management. Parameters like onset of reproduction and senescence, reproductive success and survival rate are tightly correlated with age. Unfortunately, age information of wild animals is not easy to obtain, especially for birds, where few anatomical markers of age exist. Longitudinal age data from birds banded as chicks are rare, particularly in long lived species. Age estimation in such species would be extremely useful as their long life span typically indicates slow population growth and potentially the need for protection and conservation. Telomere length change has been suggested as a universal marker for ageing vertebrates and potentially other animals. This method, termed molecular ageing, is based on a shortening of telomeres with each cell division. In birds, the telomere length of erythrocytes has been reported to decline with age, as the founder cells (haematopoietic stem cells) divide to renew circulating red blood cells. I measured telomere length in kakapo, the world largest parrot and four other bird species (Buller’s albatross, kea, New Zealand robin and saddleback) using telomere restriction fragment analysis (TRF) to assess the potential for molecular ageing in these species. After providing an overview of methods to measure telomere length, I describe how one of them (TRF) measures telomere length by quantifying the size distribution of terminal restriction fragments using southern blot of in-gel hybridization (Chapter 2). Although TRF is currently the ‘gold standard’ to measure telomere length, it suffers from various technical problems that can compromise precision and accuracy of telomere length estimation. In addition, there are many variations of the protocol, complicating comparisons between publications. I focused on TRF analysis using a non-radioactive probe, because it does not require special precautions associated with handling and disposing of radioactive material and therefore is more suitable for ecology laboratories that typically do not have a strong molecular biology infrastructure. However, most of my findings can be applied to both, radioactive and nonradioactive TRF variants. I tested how sample storage, choice of restriction enzyme, gel Abstract II electrophoresis and choice of hybridization buffer can influence the results. Finally, I show how image analysis (e.g. background correction, gel calibration, formula to calculate telomere length and the analysis window) can not only change the magnitude of estimated telomere length, but also their correlation to each other. Based on these findings, I present and discuss an extensive list of methodological difficulties associated with TRF and present a protocol to obtain reliable and reproducible results. Using this optimized protocol, I then measured telomere length of 68 kakapo (Chapter 3). Almost half of the current kakapo population consists of birds that were captured as adults, hence only their minimum age is known (i.e. time from when they were found +5 years to reach adulthood). Although molecular ageing might not be able to predict chronological age accurately, as calibrated with minimum age of some birds, it should be able to compare relative age between birds. Recently, the oldest kakapo (Richard Henry) was found to show signs of reproductive senescence. The age (or telomere length) difference to Richard Henry could have been used to approximate the remaining reproductive time span for other birds. Unfortunately, there was no change of telomere length with age in cross sectional and longitudinal samples. Analysis of fitness data available for kakapo yielded correlations between telomere length and fledging success, but they were weak and disappeared when the most influential bird was excluded from analysis. The heavy management and small numbers of kakapo make conclusions about fitness and telomere length difficult and highly speculative. However, telomere length of mothers and their chicks were significantly correlated, a phenomena not previously observed in any bird. To test if the lack of telomere loss with age is specific to kakapo, I measured telomere length of one of its closest relatives: the kea (Chapter 4). Like kakapo, telomere length did not show any correlation with age. I then further assessed the usefulness of molecular ageing in birds using only chicks and very old birds to estimate the maximum TL range in an additional long lived (Buller’s albatross) and two shorter lived species (NZ robin and saddleback). In these Abstract III species, telomere length was on average higher in chicks than in adults. However, age matched individuals showed high variations in telomere length, such that age dependent and independent telomere length could not be distinguished. These data and published results from other bird species, coupled with the limitations of methodology I have identified (Chapter 2), indicate that molecular ageing does not work in most (if not all) birds in its current suggested form. Another way to measure telomere length is telomere Q-PCR, a real-time PCR based method. Measurement of the same kakapo samples with TRF and Q-PCR did not result in comparable results (Chapter 4). Through experimentation I found that differences in amplification efficiency between samples lead to unreliable estimation of telomere length using telomere Q-PCR. These differences were caused by inhibitors present in the samples. The problem of differential amplification efficiency in Q-PCR, while known, is largely ignored by the scientific community. Although some methods have been suggested to correct for differing efficiency, most of these introduce more error than they eliminate. I developed and applied an assay based on internal standard oligonucleotides that was able to corrected EDTA induced quantification errors of up to 70% with high precision and accuracy (Chapter 5). The method, however, failed when tested with other inhibitors commonly found in DNA samples extracted from blood (i.e. SDS, heparin, urea and FeCl3). PCR inhibition was highly selective in the probe-polymerase system I used, inhibiting amplification of genomic DNA, but not amplification of internal oligonucleotide or plasmid standards in the same reaction. Internal standards are a key feature of most diagnostic PCR assays to identify false negatives arising from amplification inhibition. The differential response to inhibition I identified greatly compromises the accuracy of these assays. Consequently, I strongly recommend that researchers using PCR assays with internal standards should verify that the target DNA and internal standard actually respond similarly to common inhibitors.

In eukaryotes, chromosomes are non-randomly positioned within the nucleus.  The perinuclear localization of <i>S. cerevisiae </i>telomeres provides a useful model for studying mechanisms that control chromosome positioning.  In budding yeast, telomeres tend to be localized at the nuclear periphery during early interphase, but following S phase they delocalize and remain randomly positioned within the nucleus.  In this thesis, I investigate whether DNA replication causes telomere dislodgment from the nuclear periphery. First, using live-cell fluorescence microscopy I show that delaying DNA replication causes a corresponding delay in the dislodgement of telomeres from the nuclear envelope, demonstrating that replication of individual telomeres causes their delocalization.  Second, I show that telomere dislodgment is not simply the result of recruitment of telomeres to a replication factory that is formed in the nuclear interior, since I found that telomeric DNA replication can occur either at the nuclear periphery or in the nuclear interior.  The telomere binding complex Ku is one of the factors that establishes telomere localization to the nuclear envelope.  Using a gene locus tethering assay,  I show that the Ku-mediated telomere localization pathway is inactivated after DNA replication. Based on these findings, I propose that DNA replication causes telomere delocalization by triggering stable repression of the Ku-mediated anchoring pathway.  In addition to maintaining genetic information, DNA replication may therefore regulate subnuclear organization of chromatin.

Telomeres are regions of tandem repeats at the ends of chromosomes ensuring chromosome stability or inducing replicative senescence when critically short. Telomerase extends telomeres and its catalytic subunit, telomerase reverse transcriptase is tightly regulated at multiple levels. Cancerous cells prevent telomere-mediated senescence to attain unlimited proliferation, in most cases by enhancing telomerase activity. Chronic myeloid leukaemia is characterised by the translocation, t(9;22), in haematopoietic stem cells. The resulting fusion protein exhibits constitutive tyrosine kinase activity in the cytoplasm, promoting cellular proliferation, inhibiting apoptosis and impeding cell adhesion. Changes in telomere biology have been observed in chronic myeloid leukaemic cells. The current study aimed to investigate telomere biology in 18 chronic myeloid leukaemia patients at various time intervals from date of diagnosis. Although telomeres were significantly shorter in patients compared to controls, results point to complex telomere dynamics in the malignancy. Increased telomerase activity did not necessarily accompany telomere lengthening and increased transcription of the telomerase catalytic subunit was not necessarily indicative of telomerase activity. Ultimately the current study could not detect any trends between telomere length, telomerase activity and telomerase catalytic subunit expression in chronic myeloid leukaemia patients. Together with inherent patient-to-patient variation and the high cost per assay, measurement of telomere biology does not appear to hold prognostic value in chronic myeloid leukaemia and does not warrant inclusion into a routine test repertoire.

Mutações em genes da biologia dos telômeros, causando o seu encurtamento, são as bases moleculares de um grupo heterogêneo de doenças denominadas telomeropatias. O protótipo das telomeropatias é a disceratose congênita (DC), uma falência de medula óssea, caracterizada por sinais mucocutâneos e anemia aplástica (AA). Além da DC e AA, a fibrose pulmonar (FP) e a cirrose hepática (CH) também fazem parte do espectro das telomeropatias. Como pulmão e fígado são órgãos com baixa taxa proliferativa, suspeita-se que existe outros componentes celulares interagindo com os telômeros para o estabelecimento dessas doenças. Diferentes abordagens vêm estabelecendo uma relação entre e a biologia dos telômeros e as mitocôndrias. No entanto, ainda não se sabia sobre o funcionamento mitocondrial em células primárias de pacientes com telomeropatias. No nosso estudo, utilizamos fibroblastos dermais de indivíduos saudáveis (n=4) e de pacientes (n=6), diagnosticados com diferentes telomeropatias (AA, DC, FP e CH) e telômeros abaixo do 10º percentil (curtos para a idade). Ao avaliarmos parâmetros mitocondriais, observamos um fenótipo senescente, nas células dos pacientes, que refletiu num aumento na massa mitocondrial (85%), no número de copias de DNA mitocondrial, no consumo de oxigênio (71%) e na produção de superóxidos (74%), precursor das espécies reativas de oxigênio (EROs) mitocondriais. O superóxido levou a um aumento na expressão de antioxidantes, como a SOD1 e a UCP1. Dessa maneira, o estresse oxidativo gerado pelas EROs mitocondriais parece ter um papel fundamental na patogênese das telomeropatias. Além disso, sequenciamos amostras de sangue periférico de outros 72 pacientes com falência medular, com telômeros curtos e normais, para compararmos a taxa de variantes somáticas entre os grupos. Observamos que os pacientes com falência medular e telômeros curtos apresentaram maiores frequências de variantes somáticas. Supomos que o aumento da taxa de variantes somáticas possa ser consequência do desequilíbrio redox, observado nas células dos pacientes, causando danos no DNA das células-tronco hematopoéticas.Estudos como esse podem basear discussões sobre o uso de terapias antioxidantes em pacientes com telomeropatias / Mutations in telomere-related genes are the molecular basis of a phenotypically heterogeneous group of disorders that are collectively termed telomeropathies. The prototype of telomeropathies is the dyskeratosis congenita (DC), an inherited bone marrow failure characterized by mucocutaneous stigmata and aplastic anemia (AA). In murine telomerase knockout models, telomere shortening provokes mitochondrial deficiency and increases reactive oxygen species (ROS) production. However, the mitochondrial function in human telomeropathies has not been addressed. We evaluated mitochondrial parameters in fibroblasts from four healthy individuals (controls) and six patients with inherent bone marrow failure (DC and AA), carrying pathogenic variants in TERC, DKC1, RTEL1 and POT1 genes and, consequently, telomere shortening (<10th percentile). Patient fibroblasts displayed an 85% increment in mitochondrial mass, resulting in a 71% increase in oxygen consumption in the state of maximum respiration (ETS) compared to controls. As a consequence, mitochondrial ROS production was 74% higher in patients\' fibroblasts than in controls. Increased ROS level may explain the overexpression of SOD1 and UCP1 observed in patient cells. We further assessed the mitochondrial DNA (mtDNA) copy number in fibroblasts and peripheral blood of patients with telomere shortening. The mtDNA content was significantly higher in patients compared to controls. These findings indicate that mitochondria are affected in human telomere diseases and may play a role in disease development. Furthermore, overproduction of mitochondrial ROS could induce oxidative stress and result in somatic mutations in hematopoietic stem-cells, causing clonal disorders in patients with telomeropathies