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.

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.

We previously identified cyclin B1-specific T cells and antibodies in cancer patients with cyclin B1+ tumors and also in some healthy individuals. We also demonstrated that these responses may be important in cancer immunosurveillance by showing that vaccination against cyclin B1 prevents growth of transplantable cyclin B1+ tumors in mice. Constitutive overexpression of cyclin B1 was determined to correlate with the lack of p53 function. This allowed us to use p53−/− mice as a model that better approximates human disease. p53−/− mice spontaneously develop cyclin B1+ tumors. At 5–6 weeks of age, when the mice were still healthy with no evidence of tumor, they received the cyclin B1 vaccine and were then observed for tumor growth. We demonstrate that cyclin B1 vaccination can delay spontaneous cyclin B1+ tumor growth and increases median survival of tumor bearing p53−/− mice.

Interferon α2b (IFN-α2b) at high dosage is critical to the reversal of signaling defects in T cells of melanoma patients, and to the durable effector (α DC1) polarization of dendritic cells. These immunoregulatory effects appear to be uniquely achieved with levels of IFN-α only attainable in vivo using the high-dose regimen of IFN-α2b (HDI). Three US cooperative group studies have evaluated the benefit of HDI as an adjuvant therapy for high-risk melanoma. All have demonstrated significant and durable reduction in the frequency of relapse, while the first and third trials have demonstrated significant improvements in the fractions of patients surviving compared with observation (E1684) or with a ganglioside vaccine (GMK, E1694). A meta-analysis of 13 randomized trials evaluating adjuvant IFN therapy has now also demonstrated significant benefits for IFN in terms of RFS and OS. Research of IFN-α in melanoma is now focused on identifying prognostic markers of outcome and predictors of therapeutic response.

Data suggest that the activation of immune responses and the release of inflammatory cytokines may play a role in the pathophysiology of major depression. One mechanism by which cytokines may contribute to depression is through their effects on the glucocorticoid receptor (GR). Altered GR function in depression has been demonstrated by neuroendocrine challenge tests that reliably reveal reduced GR sensitivity as manifested by nonsuppression of cortisol following dexamethasone administration in vivo and lack of immune suppression following administration of glucocorticoids in vitro. Relevant to the GR, cytokines have been shown to decrease GR expression, block translocation of the GR from cytoplasm to nucleus, and disrupt GR-DNA binding through nuclear protein-protein interactions. In addition, cytokines have been shown to increase the expression of the relatively inert GR beta isoform. Specific cytokine signaling molecules that have been shown to be involved in the disruption of GR activity include p38 mitogen-activated protein kinase, which is associated with reduced GR translocation, and signal transducer and activator of transcription (STAT)5, which binds to GR in the nucleus. Nuclear factor-κB (NF-κB) also has been shown to lead to GR suppression through mutually inhibitory GR-NF-κB nuclear interactions. Interestingly, several antidepressants have been shown to enhance GR function, as has activation of protein kinase A (PKA). Antidepressants and PKA activation have also been found to inhibit inflammatory cytokines and their signaling pathways, suggesting that drugs that target both inflammatory responses and the GR may have special efficacy in the treatment of depression.

It is proposed that the pre-cellular stage of biological evolution unraveled within networks of inorganic compartments that harbored a diverse mix of virus-like genetic elements. This stage of evolution might comprise the Last Universal Cellular Ancestor (LUCA) that more appropriately could be denoted Last Universal Cellular Ancestral State (LUCAS). This scenario for the origin of cellular life recapitulates the early ideas of J. B. S. Haldane sketched in his classic 1928 essay. However, unlike in Haldane’s day, there is now considerable support for this scenario from three major lines of comparative-genomic evidence: i) lack of homology between the core components of the DNA replication systems of the two primary lines of descent of cellular life forms, archaea and bacteria, ii) distinct membrane chemistries and lack of homology between the enzymes of lipid biosynthesis in archaea and bacteria, iii) spread of several viral hallmark genes, which encode proteins with key functions in viral replication and morphogenesis, among numerous and extremely diverse groups of viruses, in contrast to their absence in cellular life forms, iv) the extant archaeal and bacterial chromosomes appear to be shaped by accretion of diverse, smaller replicons, suggesting a continuity between the hypothetical, primordial virus stage of life’s evolution and the dynamic prokaryotic world that existed ever since. Under the viral model of pre-cellular evolution, the key components of cells including the replication apparatus, membranes, and molecular complexes involved in membrane transport and translocation originated as components of virus-like entities. The two surviving types of cellular life forms, archaea and bacteria, might have emerged from the LUCAS independently, along with, probably, numerous forms now extinct.

Enteropathogenic E. coli (EPEC) are a leading cause of infantile diarrhea in developing countries, resulting in millions of deaths each year. EPEC secrete virulence factors, also called effectors, directly into host intestinal epithelial cells via type three secretion systems. Secreted effectors then affect host signaling pathways to induce several phenotypes, which ultimately lead to disease. Among the over 20 secreted effectors is E. coli secreted protein F (EspF), a 206 amino acid protein believed to be central to EPEC pathogenesis, as it disrupts tight junction structure and function. Although the mechanism by which this occurs is unknown, EspF has recently been found to contain several protein–protein interaction domains that may be involved. We have shown EspF to interact with the endocytic regulators sorting nexin 9 (SNX9) and N-WASP via non-exclusive binding sites. These interactions induce actin polymerization in vitro, and interaction with SNX9 alters its endocytic activity, as EspF induces the formation of tubular vesicles in a manner dependent upon its interaction with SNX9. EspF, therefore, appears to hijack endocytic regulation via SNX9 and possibly N-WASP interaction, to affect an as yet unidentified pathogenic phenotype.

Our vestibular organs are simultaneously activated by our own actions as well as by stimulation from the external world. The ability to distinguish sensory inputs that are a consequence of our own actions (e.g., vestibular reafference) from those that result from changes in the external world (e.g., vestibular exafference) is essential for perceptual stability and accurate motor control. Recent work in our laboratory has focused on understanding how the brain distinguishes between vestibular reafference and exafference. Single unit recordings were made in alert rhesus monkeys during passive and voluntary (i.e., active) head movements. We found that neurons in the first central stage of vestibular processing (vestibular nuclei) but not the primary vestibular afferents can distinguish between active and passive movements. In order to better understand how neurons differentiate active from passive head motion, we systematically tested neuronal responses to different combinations of passive and active motion resulting from rotation of the head-on-body and/or head-and-body in space. We found that during active movements, a cancellation signal was generated when the activation of proprioceptors matched the motor-generated expectation.

Aromatase is an estrogen synthetase. Estrogens are female sex hormones involved in the development and growth of breast tumors. It has been of significant interest to elucidate the structure-function relationship of aromatase since its inhibitors have shown great promise in fighting breast cancer. Aromatase belongs to the cytochrome P450 family, and forms an electron-transfer complex with its partner, NADPH-cytochrome P450 reductase. Because of the membrane-bound character and heme-binding instability, no crystal structure of aromatase has been reported so far. Much remains to be investigated, including the 3-dimensional structure of aromatase, interaction between aromatase and reductase, catalytic mechanism of estrogen synthesis by aromatase, and the binding mechanism of aromatase inhibitors. This review will present current knowledge about structural and functional characteristics of aromatase to address unsolved mysteries about this enzyme.

To what extent can remaining sensory information and/or sensory biofeedback compensate for loss of vestibular information in controlling postural equilibrium? The primary role of the vestibulospinal system is as a vertical reference for control of the trunk in space, with increasing importance as the surface becomes increasingly unstable. Our studies with patients with bilateral loss of vestibular function show that vision or light touch from a fingertip can substitute as a reference for earth vertical to decrease variability of trunk sway when standing on an unstable surface. However, some patients with bilateral loss compensate better than others and we find that those with more complete loss of bilateral vestibular function compensate better than those with measurable vestibulo-ocular reflexes. In contrast, patients with unilateral vestibular loss who reweight sensory dependence to rely on their remaining unilateral vestibular function show better functional performance than those who do not increase vestibular weighting on an unstable surface. Light touch of <100 grams or auditory biofeedback can be added as a vestibular vertical reference to stabilize trunk sway during stance. Postural ataxia during tandem gait in patients with unilateral vestibular loss is also significantly improved with vibrotactile biofeedback to the trunk, beyond improvements due to practice. Vestibular rehabilitation should focus on decreasing hypermetria, decreasing an over-dependence on surface somatosensory inputs, increasing use of any remaining vestibular function, substituting or adding alternative sensory feedback related to trunk sway, and practicing challenging balance tasks on unstable surfaces.

We studied the dynamics and kinematics of saccades in a patient with severe ocular myasthenia before and after treatment with intravenous immunoglobulin (IVIG). Before therapy, horizontal saccades were hypometric, but faster than similar-sized saccades made by normal subjects. During a 5-minute test period, saccades decreased in size (fatigue effect), but remained faster than those of controls. Listing’s plane of the eye with greater ophthalmoplegia was increased in thickness. After IVIG treatment, the range of eye movements improved, but saccades remained faster than those of controls. Also, no fatigue was observed and the thickness of Listing’s plane was reduced towards the normal range. Increased peak velocity, despite progressive hypometria due to fatigue, supports the hypothesis that the pale global extraocular muscle fibers are relatively spared in myasthenia. Involvement of other extraocular muscle fiber types leads to limited range of eye movements and an increase in the thickness of Listing’s plane.

Signal transducer and activator of transcription-3 (STAT-3) is one of six members of a family of transcription factors. It was discovered almost 15 years ago as an acute-phase response factor. This factor has now been associated with inflammation, cellular transformation, survival, proliferation, invasion, angiogenesis, and metastasis of cancer. Various types of carcinogens, radiation, viruses, growth factors, oncogenes, and inflammatory cytokines have been found to activate STAT-3. STAT-3 is constitutively active in most tumor cells but not in normal cells. Phosphorylation of STAT-3 at tyrosine 705 leads to its dimerization, nuclear translocation, DNA binding, and gene transcription. The phosphorylation of STAT-3 at serine 727 may regulate its activity negatively or positively. STAT-3 regulates the expression of genes that mediate survival (survivin, bcl-xl, mcl-1, cellular FLICE-like inhibitory protein), proliferation (c-fos, c-myc, cyclin D1), invasion (matrix metalloproteinase-2), and angiogenesis (vascular endothelial growth factor). STAT-3 activation has also been associated with both chemoresistance and radioresistance. STAT-3 mediates these effects through its collaboration with various other transcription factors, including nuclear factor-κB, hypoxia-inducible factor-1, and peroxisome proliferator activated receptor-γ. Because of its critical role in tumorigenesis, inhibitors of this factor’s activation are being sought for both prevention and therapy of cancer. This has led to identification of small peptides, oligonucleotides, and small molecules as potential STAT-3 inhibitors. Several of these small molecules are chemo-preventive agents derived from plants. This review discusses the intimate relationship between STAT-3, inflammation, and cancer in more detail.

Rift Valley fever virus (RVFV), which belongs to the genus Phlebovirus, family Bunyaviridae, is a negative-stranded RNA virus carrying a single-stranded, tripartite RNA genome. RVFV is an important zoonotic pathogen transmitted by mosquitoes and causes large outbreaks among ruminants and humans in Africa and the Arabian Peninsula. Human patients develop an acute febrile illness, followed by a fatal hemorrhagic fever, encephalitis or ocular diseases. A viral nonstructural protein, NSs, is a major viral virulence factor. Past studies showed that NSs suppresses the transcription of host mRNAs, including interferon-β mRNAs. Here we demonstrated that the NSs protein induced post-transcriptional downregulation of dsRNA-dependent protein kinase, PKR, to prevent phosphorylation of eIF2α and promoted viral translation in infected cells. These two biological activities of the NSs most probably have a synergistic effect in suppressing host innate immune functions and facilitate efficient viral replication in infected mammalian hosts.

Markers of hyperactive central corticotropin releasing factor (CRF) systems and CRF-related single nucleotide polymorphisms (SNPs) have been identified in patients with anxiety and depressive disorders. Designing more effective antagonists may now be guided by data showing that small molecules bind to transmembrane domains. Specifically, CRF1 receptor antagonists have been developed as novel anxiolytic and antidepressant treatments. Because CRF1 receptors become rapidly desensitized by G protein-coupled receptor kinase (GRK) and β-arrestin mechanisms in the presence of high agonist concentrations, neuronal hypersecretion of synaptic CRF alone may be insufficient to account for excessive central CRF neurotransmission in stress-induced affective pathophysiology. In addition to desensitizing receptor function, GRK phosphorylation and β-arrestin binding can shift a G protein-coupled receptor (GPCR) to signal selectively via the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK-MAPK) or Akt pathways independent of G proteins. Also, Epac-dependent CRF1 receptor signaling via the ERK-MAPK pathway has been found to potentiate brain-derived neurotrophic factor (BDNF)-stimulated TrkB signaling. Thus, genetic or acquired abnormalities in GRK and β-arrestin function may be involved in the pathophysiology of stress-induced anxiety and depression.

Intestinal electroneutral Na+ absorptive processes account for most intestinal Na+ absorption in the period between meals and also for the great majority of the increase in ileal Na+ absorption that occurs post-prandially. In most diarrheal diseases, there is inhibition of neutral NaCl absorption. Elevated levels of intracellular calcium ([Ca2+]i) are known to inhibit NaCl absorption and involve multiple components of the Ca2+ signaling pathway. The BB Na+/H+ exchanger NHE3 accounts for most of the recognized digestive changes in neutral NaCl absorption, as well as most of the changes in Na+ absorption that occur in diarrheal diseases. Previous studies have examined several aspects of Ca2+ regulation of NHE3 activity. These include phosphorylation, protein trafficking and multi-protein complex formation. In addition, recent studies have demonstrated the role of the NHERF family of PDZ domain–containing proteins in Ca2+ regulation of NHE3 activity, thereby adding a new level of complexity to understanding Ca2+-dependent inhibition of Na+ absorption. In this article, we will review the current understanding of (1) Ca2+ signaling events in intestinal epithelial cells; (2) Ca2+ regulation of intestinal electroneutral sodium absorption, which includes NHE3; and (3) the role of the NHERF family of PDZ domain–containing proteins in Ca2+ regulation of NHE3 activity. We will also present new data on using advanced imaging showing rapid BB NHE3 endocytosis in response to elevated [Ca2+]i.

Lipogenesis occurs primarily in the liver, where dietary carbohydrates control the expression of key enzymes in glycolytic and lipogenic pathways. We have recently discovered that the transcription factor XBP1, best known as a key regulator of the unfolded protein response (UPR), is required for de novo fatty acid synthesis in the liver, a function unrelated to its role in the UPR.1 XBP1 protein expression is induced in the liver by a high carbohydrate diet and directly controls the induction of critical genes involved in fatty acid synthesis. Specific deletion of XBP1 in adult liver using an inducible approach results in profound hypocholesterolemia and hypotriglyceridemia, which could be attributed to diminished production of lipids in the liver. Notably, this phenotype is not associated with fatty liver (hepatic steatosis) or significant compromise in protein secretion. XBP1 joins an already rich field of transcriptional regulatory proteins in the control of hepatic lipogenesis. Its function in lipogenesis appears to be highly significant as evidenced by the phenotype of the genetic mutant strain. A more complete understanding of the mechanisms by which XBP1 accelerates de novo fatty acid synthesis in the liver while preserving normal hepatic lipid composition is highly relevant to the treatment of diseases such as atherosclerosis and metabolic syndrome that are associated with dyslipidemia. Since excess fat accumulation in the liver could result from increased hepatic fatty acid synthesis, compounds that inhibit XBP1 activation may also be useful therapeutics for the treatment of human alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD), increasingly common causes of morbidity and mortality in the United States.

Bartter’s syndrome is a constellation of symptoms characterized by hyper-reninemic hypokalemia, metabolic alkalosis, elevated renin and aldosterone, low or normal blood pressure, and hyperplasia of the juxtaglomerular apparatus. So far, five gene mutations in proteins regulating the sodium chloride transport in the thick ascending limb of Henle’s loop have been described. However, the molecular mechanisms underlying the presentation of hypomagnesemia in some of these patients remains unclear. Claudins are a family of transmembranous proteins within the tight junctions that have been shown to be important for the paracellular movement of ions. Mutations in claudin-16 have been identified in patients with familial hypomagnesemia with hypercalciuria and nephrocalcinosis. To test the hypothesis that mutations in claudin genes may be involved in the altered magnesium and calcium transport in Bartter’s syndrome, we began to examine the genes of claudins known to be present in renal tubules in four pediatric patients with Bartter’s syndrome. All four patients were African Americans with hypomagnesemia and hypercalciuria. In this study, we did not find any mutation in the coding regions of claudin-2, -3, -4, -7, -8, -10, -11, or -16 genes in these patients. However, all patients had a single nucleotide substitution of C for T at the position of 451 of claudin-8 gene sequence that changes amino acid residue from serine to proline at the position of 151 in the second extracellular domain of claudin-8 protein. The significance of this known single nucleotide polymorphism remains to be determined.

The role of the potent proinflammatory cytokine IL-1 in disease could clinically be investigated with the development of the IL-1 blocking agent anakinra (Kineret®), a recombinant IL-1 receptor antagonist. It was first tested in patients with sepsis without much benefit but was later FDA approved for the treatment of patients with rheumatoid arthritis. More recently IL-1 blocking therapies are used successfully to treat a new group of immune-mediated inflammatory conditions, autoinflammatory diseases. These conditions include rare hereditary fever syndromes and pediatric and adult conditions of Still’s disease. Recently the FDA approved two additional longer acting IL-1 blocking agents, for the treatment of cryopyrin-associated periodic syndromes (CAPS), an IL-1 dependent autoinflammatory syndrome. The study of autoinflammatory diseases revealed mechanisms of IL-1 mediated organ damage and provided concepts to a better understanding of the pathogenesis of more common diseases such as gout and Type 2 diabetes which show initial promising results with IL-1 blocking therapy.

Determination of 2- and 16 α-hydroxylation of estradiol in patients with a variety of liver disorders using a dynamic method of quantitating the extent of hydroxylation, revealed specific and characteristic differences in the metabolic response. Patients with acute or silent variants of hepatitis B had estrogen metabolite patterns that were indistinguishable from those found in the control subjects. Female patients with Autoimmune hepatitis (formerly known as Lupoid hepatitis), however, showed a moderate significant decrease (p<0.0l) in 2-hydroxylation as compared with normal controls (mean 16.3 ± 1.9 vs 33.9 ± 2.5), with no significant change in 16α-hydroxylation. Male and female subjects with chronic alcoholic cirrhosis were almost devoid of 2-hydroxylation (mean 2.9 ± 0.5, p<0.01), but did show a significant increase in 16a-hydroxylation (p<0.01). The results, therefore, show that the alterations in patterns of biological oxidation are highly specific and do not reflect a general inability to metabolize estrogens in the cirrhotic patient. However, the results also suggest the possibility that a substantial fraction of 16α-hydroxylation may occur elsewhere in the body at sites other than in the liver, explaining why this biotransformation pathway is elevated, while the reaction at C-2 is almost absent in the alcoholic cirrhotic subjects.

Understanding the malleable determinants of cellular aging is critical to understanding human longevity. Telomeres may provide a pathway for exploring this question. Telomeres are the protective caps at the ends of chromosomes. The length of telomeres offers insight into mitotic cell and possibly organismal longevity. Telomere length has now been linked to chronic stress exposure and depression. This raises the question of how might cellular aging be modulated by psychological functioning.

We consider two psychological processes or states that are in opposition to one another--threat cognition and mindfulness--and their effects on cellular aging. Psychological stress cognitions, particularly appraisals of threat and ruminative thoughts, can lead to prolonged states of reactivity. In contrast, mindfulness meditation techniques appear to shift cognitive appraisals from threat to challenge, decrease ruminative thought, and reduce stress arousal. Mindfulness may also directly increase positive arousal states.

We review data linking telomere length to cognitive stress and stress arousal and present new data linking cognitive appraisal to telomere length. Given the pattern of associations revealed so far, we propose that some forms of meditation may have salutary effects on telomere length by reducing cognitive stress and stress arousal and increasing positive states of mind and hormonal factors that may promote telomere maintenance. Aspects of this model are currently being tested in ongoing trials of mindfulness meditation.

Smooth pursuit (SP) eye movements are used to maintain the image of a moving object relatively stable on the fovea. Even when tracking a single target over a dark background, multiple areas including frontal eye fields (FEF), middle temporal (MT) and medial superior temporal (MST) cortex contribute to converting visual signals into initial commands for SP. Signals in the cortical pursuit system reach the oculomotor cerebellum through brainstem centers including the dorsolateral pontine nucleus (DLPN), nucleus reticularis tegmenti pontis (NRTP) and pretectal nucleus of the optic tract (NOT). The relative information carried in these parallel pathways remains to be fully defined. We used multiple linear-regression modeling to estimate the relative sensitivities of cortical (MST, FEF), pontine (NRTP, DLPN) and NOT neurons to eye- and retinal-error parameters (position, velocity and acceleration) during step-ramp SP of macaques (Macaca mulatta). We found that a large proportion of pursuit-related MST and DLPN neurons were most sensitive to eye-velocity or retinal error velocity. In contrast, a large proportion of FEF and rostral NRTP neurons were most sensitive to eye-acceleration. Visual neurons in MST, DLPN and NOT neurons were most sensitive to retinal image velocity.

Children with spina bifida meningomyelocele (SBM) are impaired relative to controls in terms of discriminating strong-meter and weak-meter rhythms, so congenital cerebellar dysmorphologies that affect rhythmic movements also disrupt rhythm perception. Cerebellar parcellations in children with SBM showed an abnormal configuration of volume fractions in cerebellar regions important for rhythm function: a smaller inferior-posterior lobe, and larger anterior and superior-posterior lobes.

Prostate and breast cancer are hormone dependent malignancies of the aging male and female and require the local production of androgens and estrogens to stimulate cell proliferation. Aldo-keto reductases (AKR) play key roles in this process. In the prostate, AKR1C3 (type 5 17β-HSD) reduces Δ4-androstene-3,17-dione to yield testosterone while AKR1C2 (type 3 3α-HSD) eliminates 5α-dihydrotestosterone (5α-DHT), and AKR1C1 forms 3β-androstanediol (a ligand for ERβ). In the breast, AKR1C3 forms testosterone which is converted to 17β-estradiol by aromatase or reduces estrone to 17β-estradiol directly. AKR1C3 also acts as a prostaglandin (PG) F synthase and forms PGF2α and 11β-PGF2α, which stimulate the FP receptor, and prevent the activation of PPARγ by PGJ2 ligands. This pro-proliferative signaling may stimulate the growth of hormone dependent and independent prostate and breast cancer