While localizing sensory and motor deficits is one of the cornerstones of clinical neurology, behavioral and cognitive deficits in psychiatry remain impervious to this approach. In psychiatry, major ...challenges include the relative subtlety by which neural circuits are perturbed, and the limited understanding of how basic circuit functions relate to thought and behavior. Neurodevelopmental disorders offer a window to addressing the first challenge given their strong genetic underpinnings, which can be linked to biological mechanisms. Such links have benefited from genetic modeling in the mouse, and in this review we highlight how this small mammal is now allowing us to crack neural circuits as well. We review recent studies of mouse thalamus, discussing how they revealed general principles that may underlie human perception and attention. Controlling the magnitude (gain) of thalamic sensory responses is a mechanism of attention, and the mouse has enabled its functional dissection at an unprecedented resolution. Further, modeling human genetic neurodevelopmental disease in the mouse has shown how diminished thalamic gain control can lead to attention deficits. This breaks new ground in how we untangle the complexity of psychiatric diseases; by making thalamic circuits accessible to mechanistic dissection; the mouse has not only taught us how they fundamentally work, but also how their dysfunction can be precisely mapped onto behavioral and cognitive deficits. Future studies promise even more progress, with the hope that principled targeting of identified thalamic circuits can be uniquely therapeutic.
Transient receptor potential vanilloid-1 (TRPV1) is a nonselective cation channel, predominantly expressed in sensory neurons. TRPV1 is known to play an important role in the pathogenesis of ...inflammatory and neuropathic pain states. Previous studies suggest interactions between tumor necrosis factor- (TNF-) alpha and TRPV1, resulting in a modulation of ion channel function and protein expression in sensory neurons. We examined the effect of intrathecal administration of the ultrapotent TRPV1 agonist resiniferatoxin (RTX) on TNF-induced pain-associated behavior of rats using von Frey and hot plate behavioral testing. Intrathecal injection of TNF induces mechanical allodynia (2 and 20 ng/kg) and thermal hyperalgesia (200 ng) 24 h after administration. The additional intrathecal administration of RTX (1.9 μg/kg) alleviates TNF-induced mechanical allodynia and thermal hyperalgesia 24 h after injection. In addition, TNF increases the TRPV1 protein level and number of TRPV1-expressing neurons. Both effects could be abolished by the administration of RTX. These results suggest that the involvement of TRPV1 in TNF-induced pain offers new TRPV1-based experimental therapeutic approaches and demonstrates the analgesic potential of RTX in inflammatory pain diseases.
Bioengineered functional brain-like cortical tissue Tang-Schomer, Min D.; White, James D.; Tien, Lee W. ...
Proceedings of the National Academy of Sciences - PNAS,
09/2014, Letnik:
111, Številka:
38
Journal Article
Recenzirano
Odprti dostop
Significance A modular 3D brain-like cortical tissue is constructed with silk protein-based scaffold and ECM composite and primary cortical neurons. This tissue responds in vitro with biochemical and ...electrophysiological outcomes, mimicking observations of brain homeostasis and mechanical injury responses.
The brain remains one of the most important but least understood tissues in our body, in part because of its complexity as well as the limitations associated with in vivo studies. Although simpler tissues have yielded to the emerging tools for in vitro 3D tissue cultures, functional brain-like tissues have not. We report the construction of complex functional 3D brain-like cortical tissue, maintained for months in vitro, formed from primary cortical neurons in modular 3D compartmentalized architectures with electrophysiological function. We show that, on injury, this brain-like tissue responds in vitro with biochemical and electrophysiological outcomes that mimic observations in vivo. This modular 3D brain-like tissue is capable of real-time nondestructive assessments, offering previously unidentified directions for studies of brain homeostasis and injury.
Evolutionary medicine may provide insights into human physiology and pathophysiology, including tumor biology.
To identify mechanisms for cancer resistance in elephants and compare cellular response ...to DNA damage among elephants, healthy human controls, and cancer-prone patients with Li-Fraumeni syndrome (LFS).
A comprehensive survey of necropsy data was performed across 36 mammalian species to validate cancer resistance in large and long-lived organisms, including elephants (n = 644). The African and Asian elephant genomes were analyzed for potential mechanisms of cancer resistance. Peripheral blood lymphocytes from elephants, healthy human controls, and patients with LFS were tested in vitro in the laboratory for DNA damage response. The study included African and Asian elephants (n = 8), patients with LFS (n = 10), and age-matched human controls (n = 11). Human samples were collected at the University of Utah between June 2014 and July 2015.
Ionizing radiation and doxorubicin.
Cancer mortality across species was calculated and compared by body size and life span. The elephant genome was investigated for alterations in cancer-related genes. DNA repair and apoptosis were compared in elephant vs human peripheral blood lymphocytes.
Across mammals, cancer mortality did not increase with body size and/or maximum life span (eg, for rock hyrax, 1% 95% CI, 0%-5%; African wild dog, 8% 95% CI, 0%-16%; lion, 2% 95% CI, 0%-7%). Despite their large body size and long life span, elephants remain cancer resistant, with an estimated cancer mortality of 4.81% (95% CI, 3.14%-6.49%), compared with humans, who have 11% to 25% cancer mortality. While humans have 1 copy (2 alleles) of TP53, African elephants have at least 20 copies (40 alleles), including 19 retrogenes (38 alleles) with evidence of transcriptional activity measured by reverse transcription polymerase chain reaction. In response to DNA damage, elephant lymphocytes underwent p53-mediated apoptosis at higher rates than human lymphocytes proportional to TP53 status (ionizing radiation exposure: patients with LFS, 2.71% 95% CI, 1.93%-3.48% vs human controls, 7.17% 95% CI, 5.91%-8.44% vs elephants, 14.64% 95% CI, 10.91%-18.37%; P < .001; doxorubicin exposure: human controls, 8.10% 95% CI, 6.55%-9.66% vs elephants, 24.77% 95% CI, 23.0%-26.53%; P < .001).
Compared with other mammalian species, elephants appeared to have a lower-than-expected rate of cancer, potentially related to multiple copies of TP53. Compared with human cells, elephant cells demonstrated increased apoptotic response following DNA damage. These findings, if replicated, could represent an evolutionary-based approach for understanding mechanisms related to cancer suppression.
Sequential metabolic enzymes in glucose metabolism have long been hypothesized to form multienzyme complexes that regulate glucose flux in living cells. However, it has been challenging to directly ...observe these complexes and their functional roles in living systems. In this work, we have used wide-field and confocal fluorescence microscopy to investigate the spatial organization of metabolic enzymes participating in glucose metabolism in human cells. We provide compelling evidence that human liver-type phosphofructokinase 1 (PFKL), which catalyzes a bottleneck step of glycolysis, forms various sizes of cytoplasmic clusters in human cancer cells, independent of protein expression levels and of the choice of fluorescent tags. We also report that these PFKL clusters colocalize with other rate-limiting enzymes in both glycolysis and gluconeogenesis, supporting the formation of multienzyme complexes. Subsequent biophysical characterizations with fluorescence recovery after photobleaching and FRET corroborate the formation of multienzyme metabolic complexes in living cells, which appears to be controlled by post-translational acetylation on PFKL. Importantly, quantitative high-content imaging assays indicated that the direction of glucose flux between glycolysis, the pentose phosphate pathway, and serine biosynthesis seems to be spatially regulated by the multienzyme complexes in a cluster-size-dependent manner. Collectively, our results reveal a functionally relevant, multienzyme metabolic complex for glucose metabolism in living human cells.
Developmental disabilities, including attention-deficit hyperactivity disorder (ADHD), intellectual disability (ID), and autism spectrum disorders (ASD), affect one in six children in the USA. ...Recently, gene mutations in patched domain containing 1 (PTCHD1) have been found in ~1% of patients with ID and ASD. Individuals with PTCHD1 deletion show symptoms of ADHD, sleep disruption, hypotonia, aggression, ASD, and ID. Although PTCHD1 is probably critical for normal development, the connection between its deletion and the ensuing behavioural defects is poorly understood. Here we report that during early post-natal development, mouse Ptchd1 is selectively expressed in the thalamic reticular nucleus (TRN), a group of GABAergic neurons that regulate thalamocortical transmission, sleep rhythms, and attention. Ptchd1 deletion attenuates TRN activity through mechanisms involving small conductance calcium-dependent potassium currents (SK). TRN-restricted deletion of Ptchd1 leads to attention deficits and hyperactivity, both of which are rescued by pharmacological augmentation of SK channel activity. Global Ptchd1 deletion recapitulates learning impairment, hyper-aggression, and motor defects, all of which are insensitive to SK pharmacological targeting and not found in the TRN-restricted deletion mouse. This study maps clinically relevant behavioural phenotypes onto TRN dysfunction in a human disease model, while also identifying molecular and circuit targets for intervention.
Dive capacities of air-breathing vertebrates are dictated by onboard O
stores, suggesting that physiologic specialization of diving birds such as penguins may have involved adaptive changes in ...convective O
transport. It has been hypothesized that increased hemoglobin (Hb)-O
affinity improves pulmonary O
extraction and enhances the capacity for breath-hold diving. To investigate evolved changes in Hb function associated with the aquatic specialization of penguins, we integrated comparative measurements of whole-blood and purified native Hb with protein engineering experiments based on site-directed mutagenesis. We reconstructed and resurrected ancestral Hb representing the common ancestor of penguins and the more ancient ancestor shared by penguins and their closest nondiving relatives (order Procellariiformes, which includes albatrosses, shearwaters, petrels, and storm petrels). These two ancestors bracket the phylogenetic interval in which penguin-specific changes in Hb function would have evolved. The experiments revealed that penguins evolved a derived increase in Hb-O
affinity and a greatly augmented Bohr effect (i.e., reduced Hb-O
affinity at low pH). Although an increased Hb-O
affinity reduces the gradient for O
diffusion from systemic capillaries to metabolizing cells, this can be compensated by a concomitant enhancement of the Bohr effect, thereby promoting O
unloading in acidified tissues. We suggest that the evolved increase in Hb-O
affinity in combination with the augmented Bohr effect maximizes both O
extraction from the lungs and O
unloading from the blood, allowing penguins to fully utilize their onboard O
stores and maximize underwater foraging time.
Polymerized ionic liquid (POIL) block copolymers represent a unique class of materials for fundamental studies of single ion conduction as a function of morphology in microphase-separated polymer ...electrolytes for energy storage and conversion applications. We describe the synthesis of a series of poly(styrene-b-4-vinylbenzylalkylimidazolium bis(trifluoromethanesulfonyl)imide) (PS-b-PVBn(alkyl)ImTFSI; alkyl = CH3 (Me), n-C4H9 (Bu), n-C6H13 (Hex)) diblock copolymers (2.7–17.0 mol % POIL) via exhaustive functionalization and ion exchange of relatively narrow molecular weight dispersity poly(styrene-b-4-vinylbenzyl chloride) precursors derived from nitroxide-mediated block copolymerizations. The solid-state morphology of these PS-b-PVBn(alkyl)ImTFSI copolymers were studied using a combination of temperature-dependent synchrotron small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). From electrochemical impedance spectroscopy measurements, we observe that lamellar samples having similar compositions exhibit comparable values of conductivity (0.1 mS cm–1 at 150 °C) regardless of imidazolium alkyl substituent. The ionic conductivity of a compositionally varied series of PS-b-PVBnHexImTFSI diblocks depends nonlinearly on POIL composition (0.01 mS cm–1 for 8.6 mol % POIL and 0.1 mS cm–1 for 17.0 mol % POIL at 150 °C), thus highlighting the influence of morphology on the observed ionic conductivity of POIL block copolymers for the first time. By using different polymer processing strategies, we further demonstrate that the ionic conductivity of a single sample (8.6 mol % POIL) may vary by more than one order of magnitude depending on the long-range ordering of the microphase separated morphology. These studies indicate that macroscopic connectivity and morphological defects strongly affect the observed conductivity in these materials.
Autism spectrum disorder (ASD) is associated with noise hypersensitivity, the suboptimal extraction of meaningful signals in noisy environments. Because sensory filtering can involve distinct ...automatic and executive circuit mechanisms, however, developing circuit-specific therapeutic strategies for ASD noise hypersensitivity can be challenging. Here, we find that both of these processes are individually perturbed in one monogenic form of ASD, Ptchd1 deletion. Although Ptchd1 is preferentially expressed in the thalamic reticular nucleus during development, pharmacological rescue of thalamic perturbations in knockout (KO) mice only normalized automatic sensory filtering. By discovering a separate prefrontal perturbation in these animals and adopting a combinatorial pharmacological approach that also rescued its associated goal-directed noise filtering deficit, we achieved full normalization of noise hypersensitivity in this model. Overall, our work highlights the importance of identifying large-scale functional circuit architectures and utilizing them as access points for behavioral disease correction.
•ASD model (Ptchd1 KO) shows deficits in automatic and goal-directed noise filtering•Automatic filtering is explained by sensory thalamic deficits•Goal-directed filtering is explained by prefrontal deficits•Combinatorial targeting of both deficits rescued noise hypersensitivity
“Sensory overload” is common in autism spectrum disorder (ASD). By identifying multiple circuit abnormalities underlying perturbed automatic and goal-directed filtering in one ASD model, Nakajima et al. develop a combinatorial treatment strategy that fully normalizes noise hypersensitivity in that model.
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