Hutchinson-Gilford progeria syndrome (HGPS) is caused by a mutation in LMNA that produces an aberrant lamin A protein, progerin. The accumulation of progerin in HGPS cells leads to an aberrant nuclear morphology, genetic instability, and p53-dependent premature senescence. How p53 is activated in response to progerin production is unknown. Here we show that young cycling HGPS fibroblasts exhibit chronic DNA damage, primarily in S phase, as well as delayed replication fork progression. We demonstrate that progerin binds to PCNA, altering its distribution away from replicating DNA in HGPS cells, leading to ␥H2AX formation, ATR activation, and RPA Ser33 phosphorylation. Unlike normal human cells that can be immortalized by enforced expression of telomerase alone, immortalization of HGPS cells requires telomerase expression and p53 repression. In addition, we show that the DNA damage response in HGPS cells does not originate from eroded telomeres. Together, these results establish that progerin interferes with the coordination of essential DNA replication factors, causing replication stress, and is the primary signal for p53 activation leading to premature senescence in HGPS. Furthermore, this damage response is shown to be independent of progerin farnesylation, implying that unprocessed lamin A alone causes replication stress.KEYWORDS HGPS, progerin, senescence, aging, p53, telomere T he study of children with rare accelerated aging (progeria) syndromes has provided insight into the normal process of aging. Hutchinson-Gilford progeria syndrome (HGPS) is caused by a heterozygous, autosomal dominant mutation in LMNA (1), the gene that encodes lamin A, a key structural protein in the nuclear lamina. The lamina, a protein network that lines the inner nuclear membrane, provides structural support for the nucleus and is important for chromatin attachment, DNA replication, nuclear organization, and gene transcription in ways that are not completely understood. Farnesylation of prelamin A at the C terminus allows targeting to the inner nuclear membrane, where it is subsequently cleaved by the zinc metalloproteinase Zmpste24 to release mature lamin A into the lamina and nucleoplasm. In HGPS, the most common LMNA mutation (G608G) activates a cryptic splice donor site in exon 11, resulting in prelamin A mRNA with a 150-bp internal deletion, leading to a 50-amino-acid truncation in a region that contains the Zmpste24 cleavage site (reviewed in reference 2). The mutant lamin, termed progerin, retains the farnesyl lipid anchor, interferes with the integrity of the nuclear lamina, and causes the formation of misshapen nuclei. The retention of progerin on the inner nuclear membrane interferes with the function and normal distribution of lamin A, causing a loss of peripheral heterochromatin, increased DNA damage, impaired recruitment of DNA repair proteins to sites of DNA damage (3), and persistent activation of DNA damage response proteins (4). In addition to its
Through expert international consensus, 24 items are proposed for inclusion in a future validated adult vulvar lichen sclerosus severity scale.Supplemental digital content is available in the text.
Objective The objective of this study was to test the severity rating of the signs and architectural changes for interrater reliability among world experts via analysis of lichen sclerosus (LS) photographs. Methods A recent Delphi consensus exercise established a list of symptoms, signs, and architectural changes, which experts feel are important to include in a severity scale. Photographs of vulvar LS were manually extracted from patient charts and 50 photographs with a range of severity of signs and architectural changes were chosen. Lichen sclerosus experts were invited to take part in the study and 3 dermatologists and 3 gynecologists were selected for their expertise and geographic variety. Raters assessed the photographs for multiple signs and architectural changes as well as an overall impression of disease severity on a 4-point Likert scale. Intraclass correlation coefficients were calculated. Results The intraclass correlation coefficients were very poor for individual signs and architectural changes as well as for overall disease severity when analyzed for all 6 raters as well as when analyzed with dermatologists' and gynecologists' responses grouped separately. There were no statistically significant correlations found. Conclusions Global experts were unable to agree on any signs, architectural changes, or an overall global impression to assess vulvar LS disease severity based on analysis of vulvar photographs. Standardized descriptions regarding what constitutes mild, moderate, and severe signs and anatomical changes are required before further scale development can occur.
Pregnancy risks rise with age and the average age of first time mothers is rising. This study aimed to assess women's actual knowledge and their perceived knowledge of pregnancy complications relating to advanced maternal age. A cross-sectional survey was administered to primiparous women measuring demographics, knowledge of age-related pregnancy risks, previous counselling and health literacy. Of the 218 women surveyed, the mean knowledge score was not significantly different for women <35 years of age compared to women ≥35 years of age (p = .09). Although there was no difference in knowledge between the two groups, women ≥35 years of age perceived themselves to be more knowledgeable than those under 35 (p < .01). The majority of women (67%) wanted further counselling on this topic and indicated a preference for their doctor to counsel them (76%). Women require counselling informing them of their increased risk of complications if they begin childbearing at older ages. Impact statement What is already known on this subject: The average age of first time mothers is rising worldwide. Pregnancy risks rise with age, especially in first time mothers. Previous studies have shown that knowledge of age-related pregnancy risks correlate with educational level and health literacy. What the results of this study add: This study supports those findings and also demonstrates that perceived knowledge does not correlate with measured knowledge of age-related pregnancy risks. Women ≥35 years of age (higher-risk women) are no more knowledgeable than their younger counterparts though they perceive themselves to be better informed. Greater education regarding these risks may allow women to mitigate some of these risks through lifestyle and diet alteration and will prepare women for what to expect if these risks and complications occur. The majority of women in this study seek pregnancy information on the internet, but desire further counselling from their doctors regarding age-related pregnancy risks. What the implications are of these findings for clinical practice and/or further research: Given these results, physicians must consider making greater efforts to counsel women about pregnancy risks in advanced maternal age and tailor these conversations to suit the educational level and health literacy of each individual patient.
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