Cleavage of the pseudoprotease iRhom2 by the signal peptidase complex reveals an ER-to-nucleus signaling pathway.

iRhoms are pseudoprotease members of the rhomboid-like superfamily and are cardinal regulators of inflammatory and growth factor signaling; they function primarily by recognizing transmembrane domains of their clients. Here, we report a mechanistically distinct nuclear function of iRhoms, showing that both human and mouse iRhom2 are non-canonical substrates of signal peptidase complex (SPC), the protease that removes signal peptides from secreted proteins. Cleavage of iRhom2 generates an N-terminal fragment that enters the nucleus and modifies the transcriptome, in part by binding C-terminal binding proteins (CtBPs). The biological significance of nuclear iRhom2 is indicated by elevated levels in skin biopsies of patients with psoriasis, tylosis with oesophageal cancer (TOC), and non-epidermolytic palmoplantar keratoderma (NEPPK); increased iRhom2 cleavage in a keratinocyte model of psoriasis; and nuclear iRhom2 promoting proliferation of keratinocytes. Overall, this work identifies an unexpected SPC-dependent ER-to-nucleus signaling pathway and demonstrates that iRhoms can mediate nuclear signaling.

p63 is a key regulator of iRHOM2 signalling in the keratinocyte stress response.

Hyperproliferative keratinocytes induced by trauma, hyperkeratosis and/or inflammation display molecular signatures similar to those of palmoplantar epidermis. Inherited gain-of-function mutations in RHBDF2 (encoding iRHOM2) are associated with a hyperproliferative palmoplantar keratoderma and squamous oesophageal cancer syndrome (termed TOC). In contrast, genetic ablation of rhbdf2 in mice leads to a thinning of the mammalian footpad, and reduces keratinocyte hyperproliferation and migration. Here, we report that iRHOM2 is a novel target gene of p63 and that both p63 and iRHOM2 differentially regulate cellular stress-associated signalling pathways in normal and hyperproliferative keratinocytes. We demonstrate that p63-iRHOM2 regulates cell survival and response to oxidative stress via modulation of SURVIVIN and Cytoglobin, respectively. Furthermore, the antioxidant compound Sulforaphane downregulates p63-iRHOM2 expression, leading to reduced proliferation, inflammation, survival and ROS production. These findings elucidate a novel p63-associated pathway that identifies iRHOM2 modulation as a potential therapeutic target to treat hyperproliferative skin disease and neoplasia.

Motion sickness prevention by an 8-Hz stroboscopic environment during air transport.

INTRODUCTION: Previous research has shown that retinal slip can be a significant factor in causing motion sickness. Stroboscopic illumination may prevent retinal slip by providing snapshots of the visual environment that are brief enough so each image is stationary on the retina. METHODS: The purpose of this study was to determine the effectiveness of an 8-Hz stroboscopic environment as a motion sickness countermeasure for passengers during a nauseogenic flight in a helicopter. The study population was comprised of 18 motion sickness susceptible subjects. Subjects completed a motion sickness symptom questionnaire, a psychomotor vigilance test, weapons utilization tasks, a time estimation task, and a sustained attention task after nauseogenic flights with and without 8-Hz stroboscopic illumination in the cabin. RESULTS: Baseline-corrected scores of self-reported nausea were significantly lower after the stroboscopic condition (M = 36.57 +/- 6.95) than the nonstroboscopic condition (M = 50.88 +/- 7.36). Furthermore, the stroboscopic condition resulted in significantly better performance on the vigilance task than the nonstroboscopic condition. However, baseline-corrected scores of oculomotor symptoms were greater after the stroboscopic condition (M = 33.27 +/- 5.52) than the nonstroboscopic condition (M = 24.85 +/- 4.10). DISCUSSION: These results support the use of stroboscopic illumination as a nonpharmacologic countermeasure for motion sickness related to retinal slip. However, due to the uncontrolled nature of the flights, the possibility that these results could have been influenced by differences in motion between flights cannot be excluded. This technology should be investigated in other forms of transportation (i.e., ground vehicles).

Modafinil as a replacement for dextroamphetamine for sustaining alertness in military helicopter pilots.

INTRODUCTION: Successful military aviation operations depend on maintaining continuous day-night operations. Stimulants are easy to use and popular for sustaining performance because their utility is not dependent upon environmental or scheduling modifications. Dextroamphetamine is authorized for use by the aircrews of all U.S. military services, but its potential for abuse and subsequent addiction is of aeromedical concern. Finding an alternative stimulant, such as modafinil, that displays a low affinity for dopamine uptake binding sites would prove extremely beneficial. This study sought to establish the efficacy and safety of modafinil during actual flying operations, thus providing the operational validity desired to approve the use of modafinil for helicopter flight operations. METHODS: During two, 40-h periods of sustained wakefulness, 18 helicopter pilots (17 men, 1 woman, mean years of age = 29.5) each completed 15 flights and other evaluations, during which they received 2 of 3 experimental conditions: 3 doses at 4-h intervals of modafinil (100 mg), dextroamphetamine (5 mg), or placebo. RESULTS: Statistical results showed that modafinil, like dextroamphetamine, maintained alertness, feelings of well-being, cognitive function, judgment, risk perception, and situation awareness of sleep-deprived aviators consistently better than placebo and without side effects of aeromedical concern. DISCUSSION: Like previous research, this study strongly suggests that both drugs can maintain acceptable levels of mood and performance during sleep deprivation. The results also confirm that modafinil is well tolerated and appears to be a good alternative to dextroamphetamine for countering the debilitating mood and cognitive effects of sleep loss during sustained operations.

Cognition enhancement by modafinil: a meta-analysis.

INTRODUCTION: Currently, there are a number of pharmaceuticals available that have potential to enhance cognitive functioning, some of which may ultimately be considered for such use in military operations. Some drugs with potential for cognition enhancement have already been studied for use in military operations specific to their primary effect in sleep regulation (i.e., dextroamphetamine, modafinil, caffeine). There is considerable information available on many of these drugs. However, considerations for military appropriateness must be based on proficient research (e.g., randomly controlled trial design). METHODS: A meta-analysis was conducted to summarize the current state of knowledge of these potentially cognition-enhancing drugs. The analysis only included studies which met inclusion criteria relevant to military research. RESULTS: The results of the literature review reveal a gap in research of the enhancement properties of the drugs of interest. The results yielded three studies (all of which studied modafinil) that met the criteria. The meta-analysis of these three studies revealed a relatively weak pooled effect of modafinil on some aspects of cognitive performance in normal, rested adults. DISCUSSION: While the results of this study support the efficacy of modafinil, the main finding is the large literature gap evaluating the short- and long-term effects of these drugs in healthy adults.

Simulator sickness in a helicopter flight training school.

INTRODUCTION: Simulator sickness (SS) is a common problem during flight training and can affect both instructor pilots (IP) and student pilots (SP). This study was conducted in response to complaints about a high incidence of SS associated with use of new simulators for rotary-wing aircraft. METHODS: The problem was evaluated using the Simulator Sickness Questionnaire (SSQ) to collect data on 73 IP and 129 SP who used the new simulators. Based on analysis of these data, operator comments, and a search of the literature, we recommended limiting simulator flights to 2 h, removing unusual or unnatural maneuvers, turning off the sidescreens to reduce the field-of-view, avoiding use of improperly calibrated simulators until repaired, and stressing proper rest and health discipline among the pilots. The success of these measures was evaluated 1 yr later by collecting SSQ data on 25 IP and 50 SP. RESULTS: There was a main effect of time, in that after the recommendations were implemented, there was a significant reduction in nausea, oculomotor, and total SSQ scores from the pre-study to the post-study. There was also a main effect of experience, as IP reported significantly greater SS than SP for the same scores. DISCUSSION: Implementation of the recommendations reduced SS in the new simulators at the cost of limiting session duration and shutting down some simulator features. Although the optimal solution to the SS problem lies in addressing SS during a simulator's design stage, these recommendations can be used as interim solutions to reduce SS.

Polychlorinated biphenyl effects on avian hepatic enzyme induction and thyroid function.

Polychlorinated biphenyls (PCBs) decrease thyroid function in laboratory rodents by inducing activity of a liver enzyme, uridine diphosphate-glucuronosyltransferase (UDP-GT), thereby increasing thyroxine (T4) clearance. This loss of T4 can lead to hypothyroidism. In this study, an assay was validated for measuring UDP-GT activity toward T4 in Japanese quail. UDP-GT induction by Aroclor 1254 was evaluated in quail, and responses of quail and mice were compared. In Experiment 1, Japanese quail and Balb/c mice were dosed orally with vehicle or Aroclor 1254 (250 or 500mg/kg) and sacrificed 5days later. In Experiment 2, Japanese quail were dosed orally with vehicle or Aroclor 1254 (500mg/kg) and sacrificed 5 or 21days later. UDP-GT capacity (pmol T4 glucuronidated by the liver/minper g body weight) increased with PCB exposure with all doses and exposure times in both species. Plasma T4 tended to decrease (not significant) with both PCB doses and exposure times in quail and was significantly decreased with both doses in mice. Quail did not become hypothyroid at either dose or exposure time. In contrast, mice did become hypothyroid after a 5-day exposure. It is unclear how PCBs affect the hypothalamic-pituitary-thyroid (HPT) axis in quail, but activation of the HPT axis appears to be inhibited in mice. We believe this is the first demonstration of a T4-specific, avian UDP-GT response to PCBs. However, this avian response was less than that in mice with equivalent doses of PCBs. Thus, thyroid function in birds appears to be less vulnerable to PCBs than in mammals.