bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prolyl hydroxylase domain 2 deficiency promotes skeletal muscle fiber‐type transition via a calcineurin/NFATc1‐dependent pathway
Authors: Shin Junchul 
Published: November 2023

BackgroundHypoxia causes biological changes that are mediated by the hypoxia inducible factor‐α (HIF‐α), a key transcription factor for various compensatory responses under hypoxic condition. Also, HIF‐1α triggers the expression of slow myosin heavy chain under hypoxia, however, the downstream pathway of HIF‐1α leading to fiber‐type shift has not been elucidated. The calcineurin/NFATc1 signaling pathway is one of the pathways known as slow muscle fiber transition. Because calcineurin pathway is activated by vascular endothelial growth factor (VEGF), one of the factors induced by HIF‐1α, we hypothesized that the stabilization of HIF‐1α may lead to slow muscle fiber transition via the activation of calcineurin pathway in skeletal muscles. To induce HIF‐1α stabilization, we used a loss of function strategy to abrogate prolyl hydroxylase domain 2 (PHD2) responsible for HIF‐1α hydroxylation making HIF‐1α susceptible to ubiquitin dependent degradation by proteasome. The purpose of this study was therefore to examine the effect of HIF‐1α stabilization in PHD2 conditional knockout mouse on skeletal muscle fiber type transition and to elucidate the involvement of calcineurin pathway on muscle fiber type transition.MethodWe employed Phd2 tamoxifen driven Cre‐loxp system to generate a mouse in which Phd2 gene will be deleted upon activation of calcium‐dependent recombinase (Cre). Tamoxifen administration for consecutive 7 days was performed to delete Phd2 gene. FK‐506 was administered at 4 weeks after tamoxifen treatment for 7 consecutive days to suppress the calcineurin activity. All muscles were isolated at 6 week after tamoxifen administration. The proportion of slow fiber and capillary density were measured by immunostaining using frozen muscle section.ResultsPHD2 deficiency resulted in an increased capillary density in skeletal muscles due to the induction of vascular endothelial growth factor. It also elicited an alteration of skeletal muscle fiber phenotype toward the type I in both of soleus (35.8% in the control mice vs. 46.7% in the PHD2‐deficient mice, p<0.01) and the gastrocnemius muscle (0.94% vs. 1.89%, p<0.01). The localization of increased type I fibers appeared to correspond to the area of increased capillary density. In addition, calcineurin and nuclear factor of activated T cell (NFATc1) protein levels were increased in both the gastrocnemius and soleus muscles, suggesting that the calcineurin/NFATc1 pathway was responsible for the type I fiber transition regardless of PGC‐1α, which responded minimally to PHD2 deficiency. Indeed, we found that FK‐506, a calcineurin inhibitor, successfully suppressed slow fiber‐type formation in PHD2‐deficient mice.ConclusionThe stabilization of HIF‐1α induced by PHD2 conditional knockout elicited the transition of muscle fibers toward slow fiber‐type via a calcineurin/NFATc1 signaling pathway. PHD2 conditional knockout mice may serve as a model for chronic HIF‐1α stabilization as in mice exposed to low oxygen concentration.
Acute Intermittent Hypoxia‐Induced Plasticity: What About Micturition?
Authors: Collins William F , Catege Marianna , Solomon Irene C 
Published: November 2023

It is well documented that acute intermittent hypoxia (AIH) induces sustained respiratory motor plasticity (long‐term facilitation) lasting more than 60 minutes. The goal of the present study is to characterize possible similar effects of AIH on lower urinary tract function. To this end, bladder intravesical pressure and external urethral sphincter (EUS) EMG activity were recorded in urethane‐anesthetized, spontaneously breathing adult female Sprague Dawley rats during continuous infusion of saline into the bladder to elicit reflex micturition events. The rate of saline infusion was adjusted to achieve a baseline bladder inter‐contraction interval (ICI) of approximately 4 minutes. Following 30–40 minutes of baseline recording, rats were exposed to a single bout of AIH consisting of three five‐minute episodes of hypoxia (10% O2; 90% N2) each separated by five‐minute exposures to room air. Data acquisition continued for at least 90 minutes following the AIH exposure. In addition to the classic induction of respiratory motor plasticity, changes in reflex micturition were observed during the AIH recovery period and were characterized by sustained increases in bladder ICI (i.e., decreased voiding frequency), bladder pressure threshold (i.e., elevated intravesical pressure at the onset of an active bladder contraction) and EUS activity during bladder filling (i.e., increased EUS guarding reflex) lasting up to 60 minutes post AIH. In control experiments, sustained changes in bladder ICI, bladder pressure threshold and EUS activation were not observed following a single fifteen‐minute episode of sustained hypoxia (10% O2; 90% N2). These data suggest that AIH‐induced neuroplasticity extends beyond respiratory motor control and includes both somatic and autonomic motor function.Support or Funding InformationSupport for this project was provided by The Thomas Hartman Center for Parkinson's Research at Stony Brook University and The SUNY Brain Network of Excellence.
Role of PTEN in Hypoxic Pulmonary Vasoconstriction
Authors: Krauszman Adrienn , Mak Tak , Sheppard Dean , Szaszi Katalin , Kuebler Wolfgang 
Published: November 2023

RationaleHypoxic pulmonary vasoconstricition (HPV) optimizes ventilation/perfusion matching in the lung, and critically depends on transient receptor potential canonical (TRPC) 6 activation and trafficking to caveolae. In endothelial cells, phosphatase and tensin homolog (PTEN) has been shown to serve as a scaffold for TRPC6, enabling cell surface expression of the channel and subsequent Ca2+ entry. Moreover, Rho kinase (ROCK) is known to phosphorylate PTEN and play a role in its localization in chemotaxing neutrophils. Hence, we hypothesized that the interaction between PTEN and TRPC6 in PASMC may be required for TRPC6 translocation to caveolae and an intact HPV response in a ROCK‐dependent manner.MethodsInteraction between PTEN and TRPC6 was tested by co‐immunoprecipitation in whole lung lysates, and by proximity ligation assay in pulmonary artery smooth muscle cells (PASMC). Caveolar recruitment of proteins was assessed in PASMC by sucrose density gradient ultracentrifugation. HPV was analyzed in isolated perfused lungs as hypoxia‐induced increase in perfusion pressure. Calcium entry to PASMC was measured by Fura2 imaging.ResultsSMC specific PTEN KO mice had a lower HPV response compared to WT mice. Similarly, PTEN knock down in PASMC blunted Ca2+ influx in response to hypoxia. Hypoxia induced protein‐protein interaction between PTEN and TRPC6 in both whole lungs and PASMC, and translocated PTEN to caveolae (caveolin 1‐rich membrane fraction). Inhibition of ROCK (Y27632; 10 μM) prevented both effects and attenuated the HPV response in intact lungs.ConclusionHypoxia induces PTEN interaction with TRPC6 in PASMC, and PTEN translocation to caveolae in a ROCK‐dependent manner. Our findings identify an important role for PTEN in TRPC6 recruitment and activation downstream of ROCK and thus, in triggering HPV in a manner that is independent of its phosphatase activity.Support or Funding InformationFunded by a CIHR operational grant to WMK
Postinspiratory complex: a third excitatory respiratory oscillator
Authors: Anderson Tatiana M. , Garcia Alfredo J. , Bloom Jacob C. , Baertsch Nathan A. , Pollak Julia , Ramirez Jan‐Marino 
Published: November 2023

Mammalian respiration consists of three phases: (1) inspiration, (2) an early phase of expiration, postinspiration, and (3) a late phase of expiration. Two excitatory oscillators have been proposed for the generation of inspiration and active expiration, a conditional expiration that occurs during the late expiratory phase. However, the cellular and circuit mechanisms underlying the generation of postinspiration are largely unknown. Here we describe a third, previously undiscovered excitatory rhythm generator, the Postinspiratory Complex, or PIC, located immediately caudal to the facial nucleus and just medial and dorsal to the rostral‐most portion of the nucleus ambiguus. In this study a variety of in vitro and in vivo approaches are employed to demonstrate that this rhythmogenic kernel generates activity in the postinspiratory phase. Immunohistochemical and optogenetic techniques are utilized to reveal that PIC neurons co‐express acetylcholine and glutamate. Differential responses to neuromodulators and a distinct anatomical location distinguish the PIC from other described respiratory oscillators. Inhibitory interactions between this rhythmogenic network and the preBötzinger Complex, the network responsible for generating inspiration, establish the relative timing, but are not responsible for the generation of the burst underlying inspiratory and postinspiratory activity. Light stimulation of cholinergic PIC neurons in Chat‐cre:Ai27 mice evokes postinspiratory vagal activity in vivo that can reset the inspiratory rhythm. We therefore propose that the three phases of mammalian breathing are generated by three excitatory rhythmogenic medullary networks that are coordinated by inhibitory mechanisms.Support or Funding InformationNIH NS087828‐01NIH HL107084‐01
The pontine respiratory group partially mediates clinical opioid‐induced respiratory depression in young rabbits
Authors: Miller Justin Robert , Stuth Eckehard , Hopp Francis , Zuperku Edward , Stucke Astrid 
Published: November 2023

We have recently shown that the parabrachial nucleus (PBN), a part of the pontine respiratory group, plays an important role in the respiratory depression by clinical concentrations of intravenous (IV) opioids in adult rabbits as well as adult dogs (Prkic et al 2012). This study investigated whether the area plays a similar role in young rabbits. Each rabbit (P13–25) was anesthetized with 1–1.5 MAC sevoflurane, tracheotomized, ventilated and decerebrated. The PBN was functionally identified by microinjecting 70 nl of 50 μM AMPA (α‐Amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid) in a grid‐wise fashion with a glass multi‐barrel electrode from 1 mm rostral to 1 mm caudal of the inferior colliculi and 1–3 mm lateral of midline into the dorso‐ventral center of neuronal activity. Bilateral microinjection of the mu‐opioid agonist [D‐Ala2, N‐MePhe4, Gly‐ol]‐enkephalin (DAMGO, 100 μM, 140–350nl) into this region led to a significant decrease in breathing frequency (−16±8 bpm; P < 0.001; n=15) via increased inspiratory (−0.5s, range −1.3‐(−0.3s); P<0.01) and expiratory duration (TE= −6.4s, range −11.7‐(−1.7)s; P < 0.001). This was reversed by local microinjection of the opioid‐antagonist naloxone (1mM, 420 nl). In a separate set of animals, bilateral local injection of naloxone into the same area partially reversed the respiratory rate depression caused by systemic opiate administration (0.5 mcg/kg/min IV remifentanil) by attenuating the opiate induced increase in expiration duration (+1.8±1.4s; P < 0.001; n=12). These studies suggest that in young rabbits mu‐opioid receptors in the PBN contribute to bradypnea caused by clinically relevant doses of systemically administered opioids. The magnitude of these effects is similar to the effects observed in adult rabbits.Support or Funding InformationSupported by NIH R01GM112960‐01A1 and VA merit grant I01BX000721
Alterations in Doublecortin Expression in Human Neuronal Stem Cells in Response to Angiotensinergic Stimulation in Proliferation and Differentiation Conditions
Authors: Blanco Brigitte , Couling Leena E. , Siddiqi Nadia , Munoz James R , Speth Robert C 
Published: November 2023

Activation or inhibition of the renin‐angiotensin system (RAS) affects neuronal function and viability. We showed previously that AT2 selective stimulation of human neuronal stem cells (H‐9 derived, Life Technologies) increased cell numbers in both differentiation and proliferation medium compared to control and AT1 stimulated human neuronal stem cells. We now show that doublecortin expression in human neuronal stem cells which were seeded in chamber slides and cultured under proliferation (with EGF and FGF‐2) or differentiation (no added growth factors) conditions is altered with chronic exposure to AT1 and AT2 selective agonists. Conditions included 14 days treatment with once daily addition of the AT2 selective agonist CGP42112 (final concentration 100 nM); once daily treatment with the non‐selective Ang II receptor agonist Sar1 angiotensin II (100 nM) plus the AT2 receptor selective antagonist PD123319 (10 μM) for selective AT1 receptor stimulation; once daily treatment with PD123319 (10 μM) alone; or once daily treatment with vehicle. Following treatment, cells were immunostained for the neuroblast marker doublecortin. Doublecortin expression was reduced by AT1 selective stimulation in differentiation conditions relative to control (Control 70.9 ± 17% and AT1 14.0 ± 6.2%, p<0.01), AT2 stimulated (AT2 86.7 ± 0.6%, p<0.01) and AT2 antagonized with PD123319 (PD123319 64.4 ± 9.3%, p<0.05). In proliferation conditions, doublecortin expression was reduced by AT2 selective stimulation and AT2 antagonism compared to control and AT1 selectively stimulated cells (p<0.01: Control 96.5 ± 1.1% ; AT1 88.7 ± 1.6% ; AT2 9.1 ± 6.1% ; PD123319 2.6 ± 1.0%). These results suggest that angiotensinergic inhibition of doublecortin expression is dependent upon the presence of the growth factors EGF and FGF‐2.Support or Funding InformationR.C. Speth: Research Grant; Significant; NIH HL‐113905; Cardiovascular Neuroscience Research Fund, Nova Southeastern University. J. Munoz: President's Faculty Research Development Grant, Nova Southeastern University.
Reduced Glutamate Channel Phosphorylation in Pain‐Related Brain Areas in a Transgenic Model of Sickle Cell Disease
Authors: Towne Brooke V. , LeBlanc Dana M. , Paul Jinny A. , Gupta Kalpna , Edwards Scott 
Published: November 2023

Sickle cell disease (SCD) is associated with chronic, debilitating pain beginning in childhood and persisting throughout life. SCD patients also tend to exhibit elevated rates of depression and anxiety disorders, indicating a possible connection between recurring pain episodes and later affective or emotional dysregulation in this population. How SCD physiologically manifests within brain circuitry to mediate this link is currently unknown, although we hypothesize that alterations in glutamate plasticity in central pain centers is implicated. In the current study, we utilized a transgenic mouse model of SCD to measure protein kinase A (PKA)‐mediated phosphorylation of the excitatory AMPA glutamate receptor channel subunit GluR1 in specific brain regions associated with central nociception and the emotional dimension of pain, including the periaqueductal gray (PAG), prefrontal cortex (PFC), and hippocampus. Transgenic sickle cell mice (HbSS‐BERK) expressing human sickle hemoglobin displayed significant mechanical and thermal hyperalgesia across multiple tests of nociceptive sensitivity compared to healthy controls (HbAA‐BERK, expressing normal human adult hemoglobin). In addition, HbSS mice also exhibited reductions in GluR1 subunit phosphorylation in the PAG, PFC, and hippocampus relative to HbAA mice. This neuroadaptation is indicative of diminished excitatory transmission potential in these pain‐ and emotion‐associated brain areas. Moreover, our data are consistent with other preclinical pain models that have linked chronic, peripheral pain conditions with compromised excitatory signaling in central brain regions. These results make a strong case for greater appreciation and investigation into mechanisms linking pain sensitivity with possible affective disorder in individuals suffering from SCD. Our future plans include survey and functional magnetic resonance imaging (fMRI) studies of adolescent and young adult SCD patients to compare how our preclinical findings in HbSS mice associate with pain symptoms and brain activity in this patient population.Support or Funding InformationR01HL103733R00AA020839
Exploring neuroplasticity in acute mild traumatic brain injury
Authors: Arakaki Xianghong , Shoga Michael , Till Dale , Strickland David , Tran Thao , Gomez Megan , Li Lianyang , Zouridakis George , Dawlaty Jessica , Fonteh Alfred , Harrington Michael 
Published: November 2023

ObjectivesTo explore neuroplasticity in a longitudinal study of acute mild traumatic brain injury (mTBI).MethodsWe are using quantitative electroencephalography (qEEG) and magnetoencephalography (MEG) during the resting state and during cognitive brain stress to explore neuroplasticity in an ongoing acute mild traumatic brain injury research. Acute mTBI patients are recruited from the emergency department of Huntington Memorial Hospital in Pasadena, CA, and controls are non‐head‐trauma patients. Brain stress includes the N‐back (0‐back and 2‐back) working memory test and Color‐Word Interference Test (CWIT), administered using E‐prime software. Data were collected at three time points: within 1 week of injury, 14 days, and 30 days after injury. Behavioral as well as MEG and qEEG analysis are performed to compare the two groups.ResultsResting MEG detected low frequency activity in the mTBI group, consistent with previous publications. N‐back, in particular during 2‐back trials, and CWIT, in particular during incongruent trials, both show initial executive function impairment that improved on later visits. Time frequency analysis suggested corresponding compromised brain activity.ConclusionsThe EEG/MEG recordings during rest and brain stress are objective and sensitive to neuroplasticity in acute mTBI, and could be potential objective mTBI markers.Support or Funding InformationResearch supported by D.O.D. W81XWH‐13‐1‐0005
THE VOLTAGE‐GATED POTASSIUM CHANNEL KV1.3 AS A TARGET FOR INHIBITING DETRIMENTAL M1 MICROGLIA FUNCTIONS
Authors: Chen Yi‐Je (Jay) , Nguyen Hai M , Maezawa Izumi , Jin Lee‐Way , Wulff Heike 
Published: November 2023

Kv1.3 was first discovered in human T cells in 1984 and has since then been pursued as a potential target for immunosuppression. It was later shown to be overexpressed in effector memory T cells, suggesting that Kv1.3 blockers would be particularly useful for the treatment of T cell mediated autoimmune diseases like multiple sclerosis, psoriasis and rheumatoid arthritis. In fact, the Kv1.3 blocking peptide ShK‐186 has recently been found to be effective in Phase‐1b study for psoriatic arthritis. We hypothesized that Kv1.3 blockers might also be useful for reducing microglia activation in ischemic stroke and other neurological diseases accompanied by neuroinflammation. Starting with cultured microglia, we observed that Kv1.3 expression is up‐regulated in pro‐inflammatory M1‐like microglia and that Kv1.3 blockers preferentially reduce the production of IL‐1beta and TNF‐alpha without affecting IL‐10 production. In organotypic hippocampal slices exposed to hypoxia/aglycemia Kv1.3 blockers significantly reduced microglia activation and increased neuronal survival. We further observed strong Kv1.3 expression on iNOS expressing inflammatory microglia in human stroke biopsies validating Kv1.3 as potential target. In both mouse and rat models of ischemic stroke the small molecule Kv1.3 blocker PAP‐1 significantly reduced infarct area and improved neurological deficit 7 days after reperfusion when administered 12 hours after reperfusion. In the mouse model, PAP‐1 selectively reduced brain levels of the inflammatory cytokines IL1‐beta and IFN‐gamma without affecting IL‐10 and BDNF. Based on these findings we propose Kv1.3 inhibitors as potential therapeutic agents for preferentially inhibiting pro‐inflammatory M1 microglia functions in ischemic stroke and other neurological diseases.Support or Funding InformationSupported by GM076063 and AG043788.
Translating TNFR signalling into neuroprotective strategies: Proof of concept in acute in vivo models of neurodegeneration using humanized TNFR mice
Authors: Eisel Ulrich L. M. , Dong Yun , Fischer Roman , Naudé Pieter , Maier Olaf , Nyakas Csaba , van der Zee Eddy , Guenzi Eric , Herrmann Andreas , Kontermann Roland , Pfizenmaier Klaus 
Published: November 2023

TNF is involved in several degenerative brain diseases including stroke, Multiple Sclerosis, Parkinson's disease and Alzheimer's disease (AD). It became apparent in recent years that TNFR1 and TNFR2 signalling diverges with respect to its involvement in neurodegeneration and neuroprotection, respectively (Fontaine et al., 2002; Marchetti et al., 2004; Dolga et al., 2008; 2009; Fischer et al., 2011; Naudé et al., 2012; Maier et al., 2013). Under chronic stimulation TNFR2 mediated signalling counteracts TNFR1 mediated pro‐apoptotic pathways by the activation of a PI3K, PKB/Akt dependent NF‐kB signalling pathway. This allows neuronal survival despite exposure to lethal concentrations of neurotoxins such as glutamate (NMDA) or oligomeric forms of Amyloid beta. Both agents are known to be involved in neuronal cell loss in the course of Alzheimer's disease.Consequently in recent years new compounds have been developed that – instead of targeting TNF itself – selectively target TNFR1 or TNFR2 as potential therapeutics in human neurodegenerative diseases. Here we show the results of blocking either human TNFR1 or activating human TNFR2 in a mouse model with humanized TNFRs. For generating humanized TNFR mice we used gene targeting to replace the extracellular domains of the mouse TNFR genes by their human counterpart.Loss of cholinergic innervation is one of the earliest hallmarks in AD, which leads to severe cognitive impairment. Cholinergic neurons project their fibres from the Nucleus Basalis of Meynert (NBM) into the hippocampus and prefrontal cortex. Therefore loss of neurons in the NBM will reduce fibre density in the hippocampus and prefrontal cortex and lead to memory and learning deficits. We have established the NBM lesion model in humanized TNFR mice to investigate in vivo the potential therapeutic role of either TNFR1 antagonists or TNFR2 agonists. By using optical density measurements of stained cholinergic fibres and microglial activation in brain sections we were able to quantify the amount of neuronal cell loss eight days upon delivery of a toxic dose of NMDA into the Nucleus basalis via stereotactic injection. Controlateral NBM damage was used as internal standard. Behavioural testing was performed to assess cognitive function. Our results suggest that both, blocking TNFR1 or activating TNFR2, results in neuroprotection in this acute lesioning model, which serves as a paradigm for neuronal loss in chronic neurodegenerative diseases such as AD.Support or Funding InformationParts of this work was funded by EU FP6 NeuroproMiSe, ZonMW Deltaplan Dementie Memorabel Program, Internationale Stichting Alzheimer Onderzoek, Netherlands, Carl‐Zeiss‐Stiftung, Hertie Stiftung, BMBF, Germany.