Acute myocardial infarction is still one of the leading causes of death in the industrial nations. Even after successful revascularization, myocardial ischemia results in a loss of cardiomyocytes and scar formation. Embryonic EPCs (eEPCs), retroinfused into the ischemic region of the pig heart, provided rapid paracrine benefit to acute and chronic ischemia in a PI-3K/Akt-dependent manner. In a model of acute myocardial ischemia, infarct size and loss of regional myocardial function decreased after eEPC application, unless cell pre-treatment with thymosin β4 shRNA was performed. Thymosin β4 peptide retroinfusion mimicked the eEPC-derived improvement of infarct size and myocardial function. In chronic ischemia (rabbit model), eEPCs retroinfused into the ischemic hindlimb enhanced capillary density, collateral growth, and perfusion. Therapeutic neovascularization was absent when thymosin β4 shRNA was introduced into eEPCs before application. In conclusion, eEPCs are capable of acute and chronic ischemia protection in a thymosin β4 dependent manner.
thymosin β4; progenitor cells; ischemia/reperfusion; infarct size; angiogenesis
This paper reviews age differences in emotion processing and how they may relate to age-related changes in the brain. Compared with younger adults, older adults react less to negative situations, ignore irrelevant negative stimuli better, and remember relatively more positive than negative information. Older adults’ ability to insulate their thoughts and emotional reactions from negative situations is likely due to a number of factors, such as being less influenced by interoceptive cues, selecting different emotion regulation strategies, having less age-related decline in prefrontal regions associated with emotional control than in other prefrontal regions, and engaging in emotion regulation strategies as a default mode in their everyday lives. Healthy older adults’ avoidance of processing negative stimuli may contribute to their well-maintained emotional well-being. However, when cardiovascular disease leads to additional prefrontal white matter damage, older adults have fewer cognitive control mechanisms available to regulate their emotions, making them more vulnerable to depression. In general, while age-related changes in the brain help shape emotional experience, shifts in preferred strategies and goal priorities are also important influences.
emotion regulation; aging; fMRI; ventromedial prefrontal cortex; amygdala
Neonatal spinalized (NST) rats can achieve autonomous weight supported locomotion never seen after adult injury. Mechanisms that support function in NST rats include increased importance of cortical trunk control, and altered biomechanical control strategies for stance and locomotion. Hindlimbs are isolated from perturbations in quiet stance and act in opposition to forelimbs in locomotion in NST rats. Control of roll and yaw of the hindlimbs is crucial in their locomotion. The biomechanics of the hind limbs of NST rats are also likely crucial. We present new data showing the whole leg musculature scales proportional to normal rat musculature in NST rats, regardless of function. This scaling is a prerequisite for the NST rats to most effectively use pattern generation mechanisms and motor patterns that are similar to those present in intact rats. Pattern generation may be built into the lumbar spinal cord by evolution and matched to the limb biomechanics, so preserved muscle scaling may be essential to the NST function observed.
Though iron and oxygen are required to sustain essential biological processes, an excess of either can result in oxidative stress. Therefore, mammals tightly regulate cellular and systemic iron and oxygen homeostasis. At the cellular level, the hypoxia-inducible transcription factors (HIFs) are key mediators of oxygen homeostasis through their regulation of genes involved in anaerobic metabolism and oxygen delivery, among others. Iron regulatory proteins (IRPs) largely govern cellular iron homeostasis through their effects on the translation and stability of mRNAs involved in iron uptake, utilization, export, and storage. Here, we describe regulatory factors for each pathway that sense both iron and oxygen availability and coordinate the maintenance of mammalian iron and oxygen homeostasis at both the cellular and systemic levels.
iron; oxygen; hypoxia; iron regulatory protein (IRP); hypoxia-inducible factor (HIF); FBXL5; iron- and 2-oxoglutarate-dependent dioxygenase; hemerythrin
Oligomeric complexes of G protein–coupled receptors (GPCRs) are now commonly recognized and can provide a mechanism for regulation of signaling systems. Receptor oligomerization has been most extensively studied using coimmunoprecipitation and bioluminescence or fluorescence resonance energy-transfer techniques. Here, we have utilized decay of time-resolved fluorescence anisotropy of yellow fluorescent protein-labeled cholecystokinin receptor constructs to examine the state of oligomerization of this receptor in living cells. The rotational correlation times established that the cholecystokinin receptor is constitutively present in an oligomeric state that is dissociated in response to agonist occupation. In contrast, antagonist occupation failed to modify this signal, leaving the oligomeric structure intact. This dynamic technique complements the other biochemical and steady-state fluorescence techniques to establish the presence of oligomeric receptor complexes in living cells.
G protein–coupled receptors; cholecystokinin receptor; receptor oligomerization; time-resolved anisotropy; rotational dynamics
The critical discovery in the past two decades of the Transient Receptor Potential (TRP) superfamily of ion channels has revealed the potential mechanisms by which cells sense diverse stimuli beyond the prototypical “five senses”, identifying ion channels that are gated by heat, cold, mechanical loading, osmolarity, and other physical and chemical stimuli. Transient receptor potential vanilloid 4 (TRPV4) is a Ca2+-permeable non-selective cation channel that appears to play a mechano- or osmosensory roles in several musculoskeletal tissues. In articular cartilage, TRPV4 exhibits osmotic sensitivity, controlling cellular volume recovery and other physiologic responses to osmotic stress. TRPV4 is expressed in both osteoblasts and osteoclasts, and the absence of TRPV4 prevents disuse-induced bone loss. TRPV4 activation promotes chondrogenesis by inducing SOX9 transcription, whereas a TRPV4 gain-of-function mutation leads to a developmental skeletal dysplasia, suggesting a critical role for TRPV4 in skeletal development. These studies provide mounting evidence for a regulatory role for the sensory channel TRPV4 in control of musculoskeletal tissues.
osteoarthritis; osteoporosis; stretch-activated ion channel; mechanotransduction; mechanical signal transduction; remodeling
Single-molecule fluorescence imaging has provided unprecedented access to the dynamics of ribosome function, revealing transient intermediate states that are critical to ribosome activity. Imaging platforms have now been developed that are capable of probing many hundreds of molecules simultaneously at temporal and spatial resolutions approaching the sub-millisecond time and the sub-nanometer scales. These advances enable both steady- and pre-steady state measurements of individual steps in the translation process as well as processive reactions. The data generated using these methods have yielded new, quantitative structural and kinetic insights into ribosomal activity. They have also shed light on the mechanisms of antibiotics targeting the translation apparatus, revealing features of the structure-function relationship that would be difficult to obtain by other means. This review provides an overview of the types of information that can be obtained using such imaging platforms and a blueprint for using the technique to assess how small-molecule antibiotics alter macromolecular functions.
antibiotics; ribosome; smFRET; translation; tRNA
Recent studies of the spinal motor system of zebrafish, along with work in other species, are leading to some principles that appear to underlie the organization and recruitment of motor networks in cord: (1) broad neuronal classes defined by a set of transcription factors, key morphological features, and transmitter phenotypes arise in an orderly way from different dorso-ventral zones in spinal cord; (2) motor behaviors and both motoneurons and interneurons differentiate in order from gross, often faster, movements and the neurons driving them to progressively slower movements and their underlying neurons; (3) recruitment order of motoneurons and interneurons is based upon time of differentiation; (4) different locomotor speeds involve some shifts in the set of active interneurons. Here we review these principles and some of their implications for other parts of the brain, other vertebrates, and limbed locomotion.
motoneurons; spinal interneurons; transcription factors; locomotion; motor pattern
The following on molecular aspects of esophageal development contains commentaries on esophageal striated myogenesis and transdifferentiation; conversion from columnar into stratified squamous epithelium in the mouse esophagus; the roles for BMP signaling in the developing esophagus and forestomach; and evidence of a direct conversion from columnar to stratified squamous cells in the developing esophagus.
BMP signaling; esophagus; forestomach; stratification; differentiation; myogenesis; transdifferentiation; fate mapping; embryonic esophageal culture model; columnar epithelium; stratified squamous epithelium
Obesity has various deleterious effects on health largely associated with metabolic abnormalities including abnormal glucose and lipid homeostasis that are associated with vascular injury and known cardiac, renal, and cerebrovascular complications. Advanced age is also associated with increased adiposity, decreased lean mass, and increased risk for obesity-related diseases. Although many of these obesity- and age-related disease processes have long been subsumed to be secondary to metabolic or vascular dysfunction, increasing evidence indicates that obesity also modulates nonvascular diseases such as Alzheimer's disease (AD) dementia. The link between peripheral obesity and neurode-generation will be explored, using adipokines and AD as a template. After an introduction to the neuropathology of AD, the relationship between body weight, obesity, and dementia will be reviewed. Then, population-based and experimental studies that address whether leptin modulates brain health and mitigates AD pathways will be explored. These studies will serve as a framework for understanding the role of adipokines in brain health.
adiponectin; Alzheimer; amyloid; leptin
The caudal gene family (in mice and humans Cdx1, Cdx2, and Cdx4) has been studied extensively during early development as regulators of axial elongation and antero-posterior patterning. In the adult, Cdx1 and Cdx2, but not Cdx4, have been intensively studied for their function in intestinal tissue homeostasis and the pathogenesis of gastrointestinal cancers. Involvement in embryonic hematopoiesis was first demonstrated in zebrafish, where cdx genes render posterior lateral plate mesoderm competent to respond to genes specifying hematopoietic fate, and compound mutations in cdx genes thus result in a bloodless phenotype. Parallel studies performed in zebrafish embryos and murine embryonic stem cells (ESC) delineate conserved pathways between fish and mammals, corroborating a BMP/Wnt-Cdx-Hox axis during blood development that can be employed to augment derivation of blood progenitors from pluripotent stem cells in vitro. The molecular regulation of Cdx genes appears complex, as more recent data suggest involvement of non-Hox–related mechanisms and the existence of auto- and cross-regulatory loops governed by morphogens. Here we will review the role of Cdx genes during hematopoietic development by comparing effects in zebrafish and mice and discuss their participation in malignant blood diseases.
Cdx; hematopoiesis; leukemia; Hox; blood development
The orbitofrontal cortex (OFC) has long been implicated in associative learning. Early work by Mishkin and Rolls showed that the OFC was critical for rapid changes in learned behavior, a role that was reflected in the encoding of associative information by orbitofrontal neurons. Over the years, new data—particularly neurophysiological data—have increasingly emphasized the OFC in signaling actual value. These signals have been reported to vary according to internal preferences and judgments and to even be completely independent of the sensory qualities of predictive cues, the actual rewards, and the responses required to obtain them. At the same time, increasingly sophisticated behavioral studies have shown that the OFC is often unnecessary for simple value-based behavior and instead seems critical when information about specific outcomes must be used to guide behavior and learning. Here, we review these data and suggest a theory that potentially reconciles these two ideas, value versus specific outcomes, and bodies of work on the OFC.
orbital frontal cortex; overexpectation; reward; value-guided behavior
In birds as in other vertebrates, estrogens produced in the brain by aromatization of testosterone have widespread effects on behavior. Research conducted with male Japanese quail demonstrates that effects of brain estrogens on all aspects of sexual behavior, including appetitive and consummatory components as well as learned aspects, can be divided in two main classes based on their time-course. First, estrogens via binding to estrogen receptors regulate the transcription of a variety of genes involved primarily in neurotransmission. These neurochemical effects ultimately result in the activation of male copulatory behavior after a latency of a few days. Correlatively, testosterone and its aromatized metabolites increase the transcription of the aromatase mRNA resulting in an increased concentration and activity of the enzyme that actually precedes behavioral activation. Second, recent studies with quail demonstrate that brain aromatase activity (AA) can also be modulated within minutes by phosphorylation processes regulated by changes in intracellular calcium concentration such as those associated with glutamatergic neurotransmission. The rapid up or down-regulations of brain estrogen concentration presumably resulting from these changes in AA affect, by non-genomic mechanisms with relatively short latencies (frequency increases or decreases respectively within 10–15 min), the expression of male sexual behavior in quail and also in rodents. Brain estrogens thus affect behavior on different time-scales by genomic and non-genomic mechanisms similar to those of a hormone or a neurotransmitter.
copulatory behavior; appetitive sexual behavior; sexual learning; rhythmic contractions of the cloacal gland sphincter; medial preoptic area; non genomic effects of steroids; aromatase; Japanese quail - estrogens
The established role for Phosphatidylinositol (3,4,5) triphosphate (PI(3,4,5)P3) signalling pathways is to regulate cell metabolism. More recently it has emerged that PI(3,4,5)P3 signalling via mTOR and Foxo transcription factors also controls lymphocyte trafficking by determining the repertoire of adhesion and chemokine receptors expressed by T lymphocytes. In quiescent T cells, non-phosphorylated active Foxos maintain expression of KLF2, a transcription factor that regulates expression of the chemokine receptors CCR7 and S1P1and the adhesion receptor CD62L that together control T cell transmigration into secondary lymphoid tissues. PI(3,4,5)P3 mediated activation of Protein Kinase B phosphorylates and inactivates Foxos thereby terminating expression of KLF2 and its target genes. The correct localization of lymphocytes is essential for effective immune responses and the ability of PI3K and mTOR to regulate expression of chemokine receptor and adhesion molecules puts these signaling molecules at the core of the molecular mechanisms that control lymphocyte trafficking.
Phosphatidylinositol (3,4,5) triphosphate; KLF2; CCR7; S1P1; CD62L; lymphocytes
Immunodeficient mice bearing an IL2rγnull gene permit engraftment of a functional human immune system and study of human-specific infectious agents that was not previously possible.
SCID; humanized mice; immunity; infectious disease; NSG
Sixteen neurons, including vestibular-only (VO), eye–head velocity (EHV), and position-vestibular-pause (PVP) neurons sensitive to head tilt were recorded in the rostromedial and in superior vestibular nuclei. Projection of the otolith polarization vector to the horizontal plane (response vector orientation [RVO]) was determined before and after prolonged head orientation in side-down position. The RVO of VO neurons shifted toward alignment with the axis of gravity when the head was in the position of adaptation. PVP neurons had similar changes in RVO. There were also changes in RVO in some EHV neurons, but generally in directions not related to gravity. Modeling studies have suggested that the tendency to align RVOs with gravity leads to tuning of gravity-dependent angular vestibular ocular reflex (aVOR) gain changes to the position of adaptation. Thus, coding of orientation in PVP neurons would contribute significantly to the gravity-dependent adaptation of the aVOR.
adaptation; monkey; VOR; gravity
Remarkable progress has been made in recent years towards understanding the functions of the orbitofrontal cortex (OFC). The finding that neurons in this area encode the subjective value monkeys assign to different goods while choosing has been confirmed and extended by numerous studies using both primate neurophysiology and human imaging. Moreover, new lesion studies demonstrated that subjective values computed in the OFC are causally and specifically related to choice behavior. Importantly, values in the OFC are attached to goods, not to actions or to spatial locations. Furthermore, subjective values appear to be computed in this area even if the situation does not require a choice. In the light of this growing body of work, we propose that the computation of good identities and subjective values in an abstract representation is the primary function of the OFC. In this view, OFC neurons compute the subjective value of a good whenever that good is behaviorally relevant.
abstract representation; transitivity; context adaptation; decision making; economic choice; neuroeconomics
Approximately half of adults with diabetes have at least one comorbid condition. However, diabetes care guidelines focus on diabetes-specific care, and their recommendations may not be appropriate for many patients with diabetes and comorbidity. We describe Piette and Kerr's typology of comorbid conditions, which categorizes conditions based on if they are clinically dominant (eclipse diabetes management), symptomatic versus asymptomatic, and concordant (similar pathophysiologic processes as diabetes) versus discordant. We integrate this typology with clinical evidence and shared decision-making methods to create an algorithmic approach to prioritizing care in patients with diabetes and comorbidity. Initial steps are determining the patient's goals of care and preferences for treatment, whether there is a clinically dominant condition or inadequately treated symptomatic condition, and the risk of cardiovascular disease. With these data in hand, the clinician and patient prioritize diabetes treatments during a shared decision-making process. These steps should be repeated, especially when the patient's clinical status changes. This patient-centered process emphasizes overall quality of life and functioning rather than a narrow focus on diabetes.
diabetes mellitus; comorbidity; multimorbidity; prioritization
Common variable immunodeficiency (CVID) is considered to be a collection of genetic immune defects with complex inheritance patterns. While the main phenotype is loss of B cell function, the majority of the genetic mechanisms leading to CVID remain elusive. In the past two decades there have been increasing efforts to unravel the genetic defects in CVID. Here, we provide an overview of our current understanding of the genetic basis of these defects, as revealed over time by earlier linkage studies in large cohorts, analysis of families with recessive inheritance, targeted gene approaches, and genome-wide association studies using single nucleotide polymorphism arrays and copy number variation, and whole genome studies.
common variable immunodeficiency; hypogammaglobulinemia; IgA deficiency; genome-wide association studies; single nucleotide polymorphism; copy number variations; recessive genes
Rheumatoid arthritis (RA) is a chronic autoimmune disease with episodic flares in affected joints, whose etiology is largely unknown. Recent studies in mice demonstrated alterations in lymphatics from affected joints precede flares. Thus, we aimed to develop novel methods for measuring lymph node pressure and lymph viscosity in limbs of mice. Pressure measurements were performed by inserting a glass micropipette connected to a pressure transducer into popliteal lymph nodes (PLN) or axillary lymph nodes (ALN) of mice and determined that the lymphatic pressures were 9 and 12 cm of water, respectively. We are also developing methods for measuring lymph viscosity in lymphatic vessels afferent to PLN, which can be measured by multi-photon fluorescence recovery after photobleaching (MP-FRAP) of FITC-BSA injected into the hind footpad. These results demonstrate the potential of lymph node pressure and lymph viscosity measurements, and warrant future studies to test these outcomes as biomarkers of arthritic flare.
Rheumatoid Arthritis; Lymph Node; Flare; Lymphatic Pressure; Lymph Viscosity
Histone deacetylases (HDACs) remove the acetyl groups from the lysine residues of histone tails, leading to the formation of a condensed and transcriptionally silenced chromatin. HDAC inhibitors (HDACi) block this action and can result in hyperacetylation of histones, leading to a less compact and more transcriptionally active chromatin and thereby, gene expression. Previously, we have shown that HDACi inhibit osteoclast differentiation. However, which genes are transcriptionally activated following hyperacetylation of histones, and lead to the suppression of osteoclastogenesis, has yet to be elucidated. In this study, we show that a HDACi, trichostatin A (TSA), inhibits receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL) stimulated TNF-α production, NF-κB activation and bone resorbing pit formation and down-regulates cFos and NFATc1 in RAW264.7 cells. Interestingly, anti-osteoclastogenic factors CCAAT enhancer binding protein (C/EBP)-β and mitogen activated protein kinase phosphatase (MKP)-1 expression were significantly up-regulated in TSA-treated RANKL-stimulated RAW264.7 cells. These findings suggest that TSA up-regulates the expression of C/EBP-β and MKP-1 which may down-regulate pro-osteoclastogenic factors and signaling molecules, ultimately suppressing osteoclastogenesis.
Behavioral changes driven by reinforcement and punishment are referred to as simple or model-free reinforcement learning. Animals can also change their behaviors by observing events that are neither appetitive nor aversive, when these events provide new information about payoffs available from alternative actions. This is an example of model-based reinforcement learning, and can be accomplished by incorporating hypothetical reward signals into the value functions for specific actions. Recent neuroimaging and single-neuron recording studies showed that the prefrontal cortex and the striatum are involved not only in reinforcement and punishment, but also in model-based reinforcement learning. We found evidence for both types of learning, and hence hybrid learning, in monkeys during simulated competitive games. In addition, in both the dorsolateral prefrontal cortex and orbitofrontal cortex, individual neurons heterogeneously encoded signals related to actual and hypothetical outcomes from specific actions, suggesting that both areas might contribute to hybrid learning.
belief learning; decision making; game theory; reinforcement learning; reward
Mendelian susceptibility to mycobacterial disease (MSMD) is a rare syndrome conferring predisposition to clinical disease caused by weakly virulent mycobacteria, such as Mycobacterium bovis Bacille Calmette Guérin (BCG) vaccines and nontuberculous, environmental mycobacteria (EM). Since 1996, MSMD-causing mutations have been found in six autosomal genes involved in IL-12/23-dependent, IFN-γ-mediated immunity. The aim of this review is to provide the description of the two described forms of X-linked recessive (XR) MSMD. Germline mutations in two genes, NEMO and CYBB, have long been known to cause other human diseases—incontinentia pigmenti (IP) and anhidrotic ectodermal dysplasia with immunodeficiency (EDA-ID) (NEMO/IKKG), and X-linked chronic granulomatous disease (CGD) (CYBB)—but specific mutations in either of these two genes have recently been shown to cause XR-MSMD. NEMO is an essential component of several NF-κB-dependent signaling pathways. The MSMD-causing mutations in NEMO selectively affect the CD40-dependent induction of IL-12 in mononuclear cells. CYBB encoded for gp91phox, which is an essential component of the NADPH oxidase in phagocytes. The MSMD-causing mutation in CYBB selectively affects the respiratory burst in macrophages. Mutations in NEMO and CYBB may therefore cause MSMD by selectively exerting their deleterious impact on a single signaling pathway (CD40–IL-12, NEMO) or a single cell type (macrophages, CYBB). These experiments illustrate how specific germline mutations in pleiotropic genes can dissociate signalling pathways or cell lineages, thereby resulting in surprisingly narrow clinical phenotypes.
Mycobacteria; X-linked primary immunodeficiency; NEMO; CYBB; interleukin-12; interferon-γ; monocytes; macrophages
The engineering of insulin analogs represents a triumph of structure-based protein design. A framework has been provided by structures of insulin hexamers. Containing a zinc-coordinated trimer of dimers, such structures represent a storage form of the active insulin monomer. Initial studies focused on destabilization of subunit interfaces. Because disassembly facilitates capillary absorption, such targeted destabilization enabled development of rapid-acting insulin analogs. Converse efforts were undertaken to stabilize the insulin hexamer and promote higher-order self-assembly within the subcutaneous depot toward the goal of enhanced basal glycemic control with reduced risk of hypoglycemia. Current products either operate through isoelectric precipitation (insulin glargine, the active component of Lantus®; Sanofi-Aventis) or employ an albumin-binding acyl tether (insulin detemir, the active component of Levemir®; Novo-Nordisk). To further improve pharmacokinetic properties, modified approaches are presently under investigation. Novel strategies have recently been proposed based on subcutaneous supramolecular assembly coupled to (a) large-scale allosteric reorganization of the insulin hexamer (the TR transition), (b) pH-dependent binding of zinc ions to engineered His-X3-His sites at hexamer surfaces, or (c) the long-range vision of glucose-responsive polymers for regulated hormone release. Such designs share with wild-type insulin and current insulin products a susceptibility to degradation above room temperature, and so their delivery, storage, and use require the infrastructure of an affluent society. Given the global dimensions of the therapeutic supply chain, we envisage that concurrent engineering of ultra-stable protein analog formulations would benefit underprivileged patients in the developing world.
protein design; bottom-up; nanotechnology; zinc finger; hormone
The availability of immunodeficient mice engrafted with functional human immune systems and islets permits in vivo study of human diabetes without putting patients at risk.
diabetes; humanized mice; animal models; islets