216 research outputs found
Cockayne Syndrome Mouse Models: linking impaired DNA repair and premature aging
DNA damage can be deleterious to both cells as well as the entire organism. Thus, it is of vital
importance that the genome is protected from genotoxic insults. Unrepaired DNA damage can
interfere with cellular key processes like transcription and replication, resulting in cell death by
apoptosis, and growth arrest or they induce mutations that ultimately may result in the onset of
cancer (see (Hoeijmakers, 2001)). Accumulation of DNA damage has also proposed to be a
major contributor to age-related diseases (e.g. (Hasty et al., 2003; Mitchell et al., 2003)). This is
demonstrated by Cockayne Syndrome (CS), an inherited progeroid disorder, which is caused by
a defect in the transcription coupled repair subpathway of nucleotide excision repair (TC-NER)
CS is characterized by UV-sensitivity of the skin, progressive growth failure, together with many
neurological symptoms. CS is recognized as a “segmental” progeroid syndrome, as evident
from the observation that patients show early onset of a subset, but not all features of normal
aging. No cure is available for this disease other than treatment of the symptoms that present
themselves. In this thesis we set out to investigate the underlying mechanism that results in the
very severe progeroid phenotype observed in CS by use of existin
Synaptic proteome changes in a DNA repair deficient Ercc1 mouse model of accelerated aging
Cognitive decline is one of the earliest hallmarks of both normal and pathological brain aging. Here we used Ercc1 mutant mice, which are impaired in multiple DNA repair systems and consequently show accelerated aging and progressive memory deficits, to identify changes in the levels of hippocampal synaptic proteins that potentially underlie these age-dependent deficits. Aged Ercc1 mutant mice show normal gross hippocampal dendritic morphology and synapse numbers, and Ercc1 mutant hippocampal neurons displayed normal outgrowth and synapse formation in vitro. However, using isobaric tag for relative and absolute quantification (iTRAQ) of hippocampal synaptic proteins at two different ages, postnatal days 28 and 112, we observed a progressive decrease in synaptic ionotropic glutamate receptor levels and increased levels of G-proteins and of cell adhesion proteins. These together may cause long-term changes in synapse function. In addition, we observed a downregulation of mitochondrial proteins and concomitant upregulation of Na,K-ATPase subunits, which might compensate for reduced mitochondrial activity. Thus, our findings show that under conditions of apparent intact neuronal connectivity, levels of specific synaptic proteins are already affected during the early stages of DNA damage-induced aging, which might contribute to age-dependent cognitive decline
Accelerated Age-Related Cognitive Decline and Neurodegeneration, Caused by Deficient DNA Repair
Age-related cognitive decline and neurodegenerative diseases are a growing challenge for our societies with their aging populations. Accumulation of DNA damage has been proposed to contribute to these impairments, but direct proof that DNA damage results in impaired neuronal plasticity and memory is lacking. Here we take advantage of Ercc1(Delta/-) mutant mice, which are impaired in DNA nucleotide excision repair, interstrand crosslink repair, and double-strand break repair. We show that these mice exhibit an age-dependent decrease in neuronal plasticity and progressive neuronal pathology, suggestive of neurodegenerative processes. A similar phenotype is observed in mice where the mutation is restricted to excitatory forebrain neurons. Moreover, these neuron-specific mutants develop a learning impairment. Together, these results suggest a causal relationship between unrepaired, accumulating DNA damage, and age-dependent cognitive decline and neurodegeneration. Hence, accumulated DNA damage could therefore be an important factor in the onset and progression of age-related cognitive decline and neurodegenerative diseases
Fibulin-4 deficiency differentially affects cytoskeleton structure and dynamics as well as TGF beta signaling
Fibulin-4 is an extracellular matrix (ECM) protein essential for elastogenesis and mutations in this
An ex vivo Tissue Culture Model for the Assessment of Individualized Drug Responses in Prostate and Bladder Cancer
Urological malignancies, including prostate and bladder carcinoma, represent a major clinical problem due to the frequent occurrence of therapy resistance and the formation of incurable distant metastases. As a result, there is an urgent need for versatile and predictive disease models for the assessment of the individualized drug response in urological malignancies. Compound testing on ex vivo cultured patient-derived tumor tissues could represent a promising approach. In this study, we have optimized an ex vivo culture system of explanted human prostate and bladder tumors derived from clinical specimens and human cancer cell lines xenografted in mice. The explanted and cultured tumor slices remained viable and tissue architecture could be maintained for up to 10 days of culture. Treatment of ex vivo cultured human prostate and bladder cancer tissues with docetaxel and gemcitabine, respectively, resulted in a dose-dependent anti-tumor response. The dose-dependent decrease in tumor cells upon administration of the chemotherapeutic agents was preceded by an induction of apoptosis. The implementation and optimization of the tissue slice technology may facilitate the assessment of anti-tumor efficacies of existing and candidate pharmacological agents in the complex multicellular neoplastic tissues from prostate and bladder cancer patients. Our model represents a versatile “near-patient” tool to determine tumor-targeted and/or stroma-mediated anti-neoplastic responses, thus contributing to the field of personalized therapeutics
Defective Connective Tissue Remodeling in Smad3 Mice Leads to Accelerated Aneurysmal Growth Through Disturbed Downstream TGF-β Signaling
Aneurysm-osteoarthritis syndrome characterized by unpredictable aortic aneurysm formation, is caused by SMAD3 mutations. SMAD3 is part of the SMAD2/3/4 transcription factor, essential for TGF-β-activated transcription. Although TGF-β-related gene mutations result in aneurysms, the underlying mechanism is unknown. Here, we examined aneurysm formation and progression in Smad3−/− animals. Smad3−/− animals developed aortic aneurysms rapidly, resulting in premature death. Aortic wall immunohistochemistry showed no increase in extracellular matrix and collagen accumulation, nor loss of vascular smooth muscle cells (VSMCs) but instead revealed medial elastin disruption and adventitial inflammation. Remarkably, matrix metalloproteases (MMPs) were not activated in VSMCs, but rather specifically in inflammatory areas. Although Smad3−/− aortas showed increased nuclear pSmad2 and pErk, indicating TGF-β receptor activation, downstream TGF-β-activated target genes were not upregulated. Increased pSmad2 and pErk staining in pre-aneurysmal Smad3−/− aortas implied that aortic damage and TGF-β receptor-activated signaling precede aortic inflammation. Finally, impaired downstream TGF-β activated transcription resulted in increased Smad3−/− VSMC proliferation. Smad3 deficiency leads to imbalanced activation of downstream genes, no activation of MMPs in VSMCs, and immune responses resulting in rapid aortic wall dilatation and rupture. Our findings uncover new possibil
In vivo renin activity imaging in the kidney of progeroid Ercc1 mutant mice
Changes in the renin-angiotensin system, known for its critical role in the regulation of blood pressure and sodium homeostasis, may contribute to aging and age-related diseases. While the renin-angiotensin system is suppressed during aging, little is known about its regulation and activity within tissues. However, this knowledge is required to successively treat or prevent renal disease in the elderly. Ercc1 is involved in important DNA repair pathways, and when mutated causes accelerated aging phenotypes in humans and mice. In this study, we hypothesized that unrepaired DNA damage contributes to accelerated kidney failure. We tested the use of the renin-activatable near-infrared fluorescent probe ReninSense680™ in progeroid Ercc(1d/-) mice and compared renin activity levels in vivo to wild-type mice. First, we validated the specificity of the probe by detecting increased intrarenal activity after losartan treatment and the virtual absence of fluorescence in renin knock-out mice. Second, age-related kidney pathology, tubular anisokaryosis, glomerulosclerosis and increased apoptosis were confirmed in the kidneys of 24-week-old Ercc(1d/-) mice, while initial renal development was normal. Next, we examined the in vivo renin activity in these Ercc(1d/-) mice. Interestingly, increased intrarenal renin activity was detected by ReninSense in Ercc(1d/-) compared to WT mice, while their plasma renin concentrations were lower. Hence, this study demonstrates that intrarenal RAS activity does not necessarily run in parallel with circulating renin in the aging mouse. In addition, our study supports the use of this probe for longitudinal imaging of altered RAS signaling in aging
Chronic fatigue in childhood cancer survivors is associated with lifestyle and psychosocial factors; a DCCSS LATER study
Background: The purpose of this study was to determine factors associated with chronic fatigue (CF) in childhood cancer survivors (CCS). Patients and methods: Participants were included from the Dutch Childhood Cancer Survivor Study (DCCSS) LATER cohort, a nationwide cohort of CCS (≥5 years after diagnosis) and siblings as controls. Fatigue severity was assessed with the ‘fatigue severity subscale’ of the Checklist Individual Strength (‘CIS-fatigue’). CF was defined as scoring ≥35 on the ‘CIS-fatigue’ and having fatigue symptoms for ≥6 months. Twenty-four parameters were assessed, categorized into assumed fatigue triggering, maintaining and moderating factors. Multivariable logistic regression analyses were carried out to investigate the association of these factors with CF. Results: A total of 1927 CCS participated in the study (40.7% of invited cohort), of whom 23.6% reported CF (compared with 15.6% in sibling controls, P < 0.001). The following factors were associated with CF: obesity [versus healthy weight, odds ratio (OR) 1.93; 95% confidence interval (CI) 1.30-2.87], moderate physical inactivity (versus physical active, OR 2.36; 95% CI 1.67-3.34), poor sleep (yes versus no, OR 2.03; 95% CI 1.54-2.68), (sub)clinical anxiety (yes versus no, OR 1.55; 95% CI 1.10-2.19), (sub)clinical depression (yes versus no, OR 2.07; 95% CI 1.20-3.59), pain (continuous, OR 1.49; 95% CI 1.33-1.66), self-esteem (continuous, OR 0.95; 95% CI 0.92-0.98), helplessness (continuous, OR 1.13; 95% CI 1.08-1.19), social functioning (continuous, OR 0.98; 95% CI 0.97-0.99) and female sex (versus male sex, OR 1.79; 95% CI 1.36-2.37). Conclusion: CF is a prevalent symptom in CCS that is associated with several assumed maintaining factors, with lifestyle and psychosocial factors being the most prominent. These are modifiable factors and may therefore be beneficial to prevent or reduce CF in CCS.</p
Gestational jet lag predisposes to later-life skeletal and cardiac disease
cardiovascular disease, and cancer. In the present study, we investigated later life adverse health
effects triggered by repeated jet lag during gestation. Pregnant mice were subjected to a regular
light-dark cycle (CTRL) or to a repeated delay (DEL) or advance (ADV) jet lag protocol. Both DEL
and ADV offspring showed reduced weight gain. ADV offspring had an increased circadian period,
and an altered response to a jet lag was observed in both DEL and ADV offspring. Analysis of the
bones of adult male ADV offspring revealed reduced cortical bone mass and strength. Strikingly,
analysis of the heart identified structural abnormalities and impaired heart function. Finally, DNA
methylation analysis revealed hypermethylation of miR17-92 cluster and differential methylation
within circadian clock genes, which correlated with altered gene expression. We show that
developmental CRD affects the circadian system and predisposes to non-communicable disease
in adult life
- …