HomeCCBARResearchProceedingsStudiesCentersGrants

      Governmental Agencies

       New Articles


University of Chicago Logo
National Opinion Research Center at The University of Chicago logo

Center on Demography and Economics of Aging logo

Nature Publishing Group


Nature: Current issue

Pregnant mice illuminate risk factors that could lead to autism
Studies highlight link between immune response and unusual neural wiring.

Geneticists pan paper that claims to predict a person's face from their DNA
Reviewers and a co-author of a paper by genomics entrepreneur Craig Venter claim that it misrepresents the risks of public access to genome data.

Climate science: The future of Asia's glaciers
Glaciers in the high mountains of Asia are a crucial water resource, but are at risk from global warming. Modelling suggests that the glaciers will shed mass in direct proportion to the warming to which they are exposed. See Letter p.257


Nature Journals

Neuroscience: Mum's bacteria linked to baby's behaviour
Infection during pregnancy increases the risk of neurodevelopmental disorders, such as autism, in offspring. Mouse studies now reveal a link between gut bacteria and atypical brain-circuit connections.

The cryo-electron microscopy structure of human transcription factor IIH
Human transcription factor IIH (TFIIH) is part of the general transcriptional machinery required by RNA polymerase II for the initiation of eukaryotic gene transcription. Composed of ten subunits that add up to a molecular mass of about 500?kDa, TFIIH is also essential for nucleotide excision repair. The seven-subunit TFIIH core complex formed by XPB, XPD, p62, p52, p44, p34, and p8 is competent for DNA repair, while the CDK-activating kinase subcomplex, which includes the kinase activity of CDK7 as well as the cyclin H and MAT1 subunits, is additionally required for transcription initiation. Mutations in the TFIIH subunits XPB, XPD, and p8 lead to severe premature ageing and cancer propensity in the genetic diseases xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy, highlighting the importance of TFIIH for cellular physiology. Here we present the cryo-electron microscopy structure of human TFIIH at 4.4? resolution. The structure reveals the molecular architecture of the TFIIH core complex, the detailed structures of its constituent XPB and XPD ATPases, and how the core and kinase subcomplexes of TFIIH are connected. Additionally, our structure provides insight into the conformational dynamics of TFIIH and the regulation of its activity.

Maternal gut bacteria promote neurodevelopmental abnormalities in mouse offsp...
Maternal immune activation (MIA) contributes to behavioural abnormalities associated with neurodevelopmental disorders in both primate and rodent offspring. In humans, epidemiological studies suggest that exposure of fetuses to maternal inflammation increases the likelihood of developing autism spectrum disorder. In pregnant mice, interleukin-17a (IL-17a) produced by T helper 17 (TH17) cells (CD4+ T helper effector cells involved in multiple inflammatory conditions) induces behavioural and cortical abnormalities in the offspring exposed to MIA. However, it is unclear whether other maternal factors are required to promote MIA-associated phenotypes. Moreover, the underlying mechanisms by which MIA leads to T cell activation with increased IL-17a in the maternal circulation are not well understood. Here we show that MIA phenotypes in offspring require maternal intestinal bacteria that promote TH17 cell differentiation. Pregnant mice that had been colonized with mouse commensal segmented filamentous bacteria or human commensal bacteria that induce intestinal TH17 cells were more likely to produce offspring with MIA-associated abnormalities. We also show that small intestine dendritic cells from pregnant, but not from non-pregnant, females secrete IL-1?, IL-23 and IL-6 and stimulate T cells to produce IL-17a upon exposure to MIA. Overall, our data suggest that defined gut commensal bacteria with a propensity to induce TH17 cells may increase the risk of neurodevelopmental disorders in the offspring of pregnant mothers undergoing immune system activation owing to infections or autoinflammatory syndromes.

Cell signalling: Red alert about lipid's role in skin cancer
Some versions of the MC1R protein are associated with red hair and an increased risk of developing a skin cancer called melanoma. It emerges that a lipid that binds MC1R might provide a target to reduce this risk.

Palmitoylation-dependent activation of MC1R prevents melanomagenesis
The melanocortin-1 receptor (MC1R), a G-protein-coupled receptor, has a crucial role in human and mouse pigmentation. Activation of MC1R in melanocytes by ?-melanocyte-stimulating hormone (?-MSH) stimulates cAMP signalling and melanin production and enhances DNA repair after ultraviolet irradiation. Individuals carrying MC1R variants, especially those associated with red hair colour, fair skin and poor tanning ability (denoted as RHC variants), are associated with higher risk of melanoma. However, how MC1R activity is modulated by ultraviolet irradiation, why individuals with red hair are more prone to developing melanoma, and whether the activity of RHC variants might be restored for therapeutic benefit are unknown. Here we demonstrate a potential MC1R-targeted intervention strategy in mice to rescue loss-of-function MC1R in MC1R RHC variants for therapeutic benefit by activating MC1R protein palmitoylation. MC1R palmitoylation, primarily mediated by the protein-acyl transferase ZDHHC13, is essential for activating MC1R signalling, which triggers increased pigmentation, ultraviolet-B-induced G1-like cell cycle arrest and control of senescence and melanomagenesis in vitro and in vivo. Using C57BL/6J-Mc1re/eJ mice, in which endogenous MC1R is prematurely terminated, expressing Mc1r RHC variants, we show that pharmacological activation of palmitoylation rescues the defects of Mc1r RHC variants and prevents melanomagenesis. The results highlight a central role for MC1R palmitoylation in pigmentation and protection against melanoma.

Competing memories of mitogen and p53 signalling control cell-cycle entry
Regulation of cell proliferation is necessary for immune responses, tissue repair, and upkeep of organ function to maintain human health. When proliferating cells complete mitosis, a fraction of newly born daughter cells immediately enter the next cell cycle, while the remaining cells in the same population exit to a transient or persistent quiescent state. Whether this choice between two cell-cycle pathways is due to natural variability in mitogen signalling or other underlying causes is unknown. Here we show that human cells make this fundamental cell-cycle entry or exit decision based on competing memories of variable mitogen and stress signals. Rather than erasing their signalling history at cell-cycle checkpoints before mitosis, mother cells transmit DNA damage-induced p53 protein and mitogen-induced cyclin D1 (CCND1) mRNA to newly born daughter cells. After mitosis, the transferred CCND1 mRNA and p53 protein induce variable expression of cyclin D1 and the CDK inhibitor p21 that almost exclusively determines cell-cycle commitment in daughter cells. We find that stoichiometric inhibition of cyclin D1?CDK4 activity by p21 controls the retinoblastoma (Rb) and E2F transcription program in an ultrasensitive manner. Thus, daughter cells control the proliferation?quiescence decision by converting the memories of variable mitogen and stress signals into a competition between cyclin D1 and p21 expression. We propose a cell-cycle control principle based on natural variation, memory and competition that maximizes the health of growing cell populations.

Metallic molybdenum disulfide nanosheet-based electrochemical actuators
Actuators that convert electrical energy to mechanical energy are useful in a wide variety of electromechanical systems and in robotics, with applications such as steerable catheters, adaptive wings for aircraft and drag-reducing wind turbines. Actuation systems can be based on various stimuli, such as heat, solvent adsorption/desorption, or electrochemical action (in systems such as carbon nanotube electrodes, graphite electrodes, polymer electrodes and metals). Here we demonstrate that the dynamic expansion and contraction of electrode films formed by restacking chemically exfoliated nanosheets of two-dimensional metallic molybdenum disulfide (MoS2) on thin plastic substrates can generate substantial mechanical forces. These films are capable of lifting masses that are more than 150 times that of the electrode over several millimetres and for hundreds of cycles. Specifically, the MoS2 films are able to generate mechanical stresses of about 17 megapascals?higher than mammalian muscle (about 0.3 megapascals) and comparable to ceramic piezoelectric actuators (about 40 megapascals)?and strains of about 0.6 per cent, operating at frequencies up to 1 hertz. The actuation performance is attributed to the high electrical conductivity of the metallic 1T phase of MoS2 nanosheets, the elastic modulus of restacked MoS2 layers (2 to 4 gigapascals) and fast proton diffusion between the nanosheets. These results could lead to new electrochemical actuators for high-strain and high-frequency applications.

Proteins evolve on the edge of supramolecular self-assembly
The self-association of proteins into symmetric complexes is ubiquitous in all kingdoms of life. Symmetric complexes possess unique geometric and functional properties, but their internal symmetry can pose a risk. In sickle-cell disease, the symmetry of haemoglobin exacerbates the effect of a mutation, triggering assembly into harmful fibrils. Here we examine the universality of this mechanism and its relation to protein structure geometry. We introduced point mutations solely designed to increase surface hydrophobicity among 12 distinct symmetric complexes from Escherichia coli. Notably, all responded by forming supramolecular assemblies in vitro, as well as in vivo upon heterologous expression in Saccharomyces cerevisiae. Remarkably, in four cases, micrometre-long fibrils formed in vivo in response to a single point mutation. Biophysical measurements and electron microscopy revealed that mutants self-assembled in their folded states and so were not amyloid-like. Structural examination of 73 mutants identified supramolecular assembly hot spots predictable by geometry. A subsequent structural analysis of 7,471 symmetric complexes showed that geometric hot spots were buffered chemically by hydrophilic residues, suggesting a mechanism preventing mis-assembly of these regions. Thus, point mutations can frequently trigger folded proteins to self-assemble into higher-order structures. This potential is counterbalanced by negative selection and can be exploited to design nanomaterials in living cells.


[CaRP] php_network_getaddresses: getaddrinfo failed: Name or service not known (0)
A common intronic variant of PARP1 confers melanoma risk and mediates melanoc...
Kevin Brown and colleagues functionally characterize a melanoma risk locus encompassing PARP1, correlating the risk genotype to PARP1 gene expression levels in melanoma cells. They identify an intronic gene-regulatory variant in PARP1 and find that PARP1 can promote cell proliferation and rescue oncogene-induced senescence, likely through MITF.

Effect of sequence variants on variance in glucose levels predicts type 2 dia...
Daniel Gudbjartsson, Kari Stefansson and colleagues assess the effect of variants associated with mean fasting glucose levels on the variance in fasting glucose levels. They find that variants that increase both the levels and variance of fasting glucose increase type 2 diabetes risk, whereas those that increase the levels but reduce the variance do not.

IFN-? 'guts' neutrophil-mediated inflammation
Interferon-? (IFN-?) curbs neutrophil-mediated intestinal inflammation by diminishing the production of reactive oxygen species and subsequent oxidative stress. This regulatory process is unique to IFN-? and is independent of interferon-induced transcription and translation programs.


Nature Reviews


[CaRP] php_network_getaddresses: getaddrinfo failed: Name or service not known (0)
Innate immunity: A new way out for lysozyme
Endoplasmic reticulum stress in Paneth cells induces secretory autophagy of lysozyme.

Stress responses: SIRT1 puts an embargo on mRNA export
Sirtuin 1 deacetylates polyadenylate-binding protein 1 (PABP1), thereby suppressing nuclear export of polyadenylated mRNAs and translation to preserve energy under stress.

Reward: Restraint from risky reward
In mice, a set of projections from the medial prefrontal cortex to the nucleus accumbens suppress reward seeking under risky conditions.