bluuebunny/crossref_metadata_2025 huggingface dataset:
Leucine improves markers energy metabolism in C2C12 myotubes treated with palmitate
Authors: Wu Hexirui , Dridi Sami , Baum Jamie I.
Published: June 2021

More than one‐third of adults and 17% of children in the United States are classified as obese. One contributor to the development of obesity is an increase energy intake accompanied by a decrease energy expenditure. Muscle plays an important role in energy utilization and production in human body. Excessive fat mass accumulation in muscle blunts energy production such as fatty acid oxidation. The objectives of this study were to: 1) determine if the branched‐chain amino acid leucine lowers intracellular fatty acid uptake, and 2) determine if mitochondria are involved in the leucine‐mediated effect on fatty acid uptake. C2C12 myotubes were used as a cell model for muscle. Cells were treated with palmitate for 24 hours in order create an obesogenic muscle model. All cells were serum and leucine starved for 24 hours before receiving one of the following four treatments: control (CON), palmitate (PALM, palmitate treated for 24h), palmitate + 0.5mM leucine (PALM+0.5mM LEU,, palmitate and 0.5mM leucine co‐treated for 24h), palmitate + 1.5mM leucine (PALM+1.5mM LEU,, palmitate and 1.5mM leucine co‐treated for 24h). Intracellular lipid deposition was measured using oil red o staining kit and quantified using ImageJ software. Both doses of leucine showed significant effect (p<0.05) on lowering the intake of intracellular lipid uptake in PALM treated cells. Real‐time PCR results showed higher (p<0.05) expression of uncoupling proteins (UCP2 and UCP3), which are involved in ATP synthesis, in both leucine treatment groups compared with PALM. There was no significant difference in gene expression of NRF1, SIRT1, Tfam, PPARγ and ANT1, all involved in mitochondria DNA transcription. In conclusion, these data suggest leucine promotes energy metabolism through regulating uncoupling protein in mitochondria in C2C12 myotubes, indicating a possible target for improving obesity.

Support or Funding Information

Arkansas Biosciences Institute

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Discovering drug resistance‐associated biomarkers from malignant pleural effusion of lung cancer by quantitative proteomic approaches
Authors: Yu Chia‐Jung , Chiou Ien‐Chiuam , Wang Chih‐Liang , Hsiao Ting‐Feng
Published: June 2021

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR‐TKIs) have been approved for the treatment of patients with advanced lung adenocarcinoma (ADC) harboring EGFR activating mutations. Although the EGFR‐TKIs or combined treatments of EGFR‐TKIs and chemotherapy would benefit patients, the following drug‐resistant issue eventually led to the poor survival of cancer patients. Therefore, it is important to search the drug resistance‐associated biomarkers for monitoring the treatment efficacy and/or prognosis in lung ADC. We herein applied high‐abundant protein removal system and iTRAQ‐based quantitative proteomics approach to generate the drug resistance‐associated malignant pleural effusion (MPE) proteome data sets from lung ADC patients who were sensitive, resistant to TKI, or resistant to TKI/chemotherapy. Among the 565 quantified MPE proteins, five potential biomarkers (CEACAM5, DMBT1, HGFAC, MMP3, CDHP) were isolated for preclinical validation using ELISA. The MPE levels of these five candidates were increased in patients with drug‐resistant as compared to patients with treatment naïve. Importantly, the levels of MMP3 and CDHP in serum samples were significantly associated with patients' survival and treatment efficacy. Our results collectively provide the potential biomarkers for prediction of drug resistance as well as prognosis in lung ADC.

Support or Funding Information

This work was financially supported by grants from the Ministry of Science and Technology, Taiwan (104‐2320‐B‐182‐027 and 105‐2320‐B‐182‐035‐MY3), and from Chang Gung Memorial Hospital, Taoyuan, Taiwan (BMRP894).

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
p53 mediated regulation of Coactivator associated arginine methyltransferase 1 (CARM1) expression is critical for suppression of adipogenesis
Authors: Behera Amit Kumar , Bhattacharya Aditya , Vasudevan Madavan , Kundu Tapas Kumar
Published: June 2021

Coactivator associated arginine methyltransferase 1 (CARM1/PRMT4) is a type I arginine methyltransferase that mediates transcriptional activation via methylation of histone H3 on R17, R26 and R42. CARM1 acts as a coactivator of transcription of various transcription factors such as NF‐kB, MEF2C, β‐catenin, p53, PPAR‐gamma etc. CARM1 has been functionally implicated in maintenance of pluripotency, cellular differentiation and tumorigenesis; where its expression status plays an important role. Although its expression has been shown to be regulated by a few miRNAs in different contexts at post‐transcriptional level, transcriptional regulation of CARM1 gene is still unexplored. In the present study we demonstrate that CARM1 is a p53 responsive gene, where p53 could suppress CARM1 promoter driven luciferase expression. CARM1 gene expression was found to be repressed by p53 in 3T3L1 preadipocytes when activated with Nutlin‐3a treatment. Ectopic overexpression of CARM1 could rescue inhibitory effect of p53 on adipogenesis, suggesting a role of p53‐CARM1 axis of regulation operational in the context of adipocyte differentiation. p53 and CARM1 showed antagonistic regulatory influence on PPAR‐gamma expression; which suggests that p53 mediated suppression of adipogenesis could be partly via repression of CARM1 expression. Taken together these observations provide convincing mechanistic explanation for p53 function in the context of adipocyte differentiation process.

Support or Funding Information

TKK is recipient of JC Bose fellowship from Dept. of Science and technology, Govt. of India (SR/S2/JCB‐28/2010). AKB is a research associate of JNCASR. AB is a senior research fellow of UGC, India. This work was supported by funding from Dept. of Biotchnology, Govt. of India (BT/01/CEIB/10/III/01) and JNCASR, India.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The receptor tyrosine kinases Tyro3 and Axl are co‐regulated and activate discrete signaling pathways for cancer cell proliferation and invasion respectively
Authors: Hafizi Sassan , Al Kafri Nour , Vouri Mikaella
Published: June 2021

The TAM (Tyro3, Axl, Mer) subfamily of receptor tyrosine kinases (RTKs) have been implicated in tumor growth and spread in several different cancers, with Axl in particular being shown to regulate cell invasion as well as resistance to other targeted therapies such as EGFR blockade. However, little is known about Tyro3, which although having a more restricted tissue pattern, is also found overexpressed in several solid cancers. The aim of this study is to elucidate the specific signaling pathways emanating from Tyro3 activation in cancer cells. In addition to signaling via homodimeric activation of RTKs, diversity in signaling may be achieved by cross‐talk amongst different RTKs via e.g. heterodimerization. Therefore, a further aim is to identify such novel, unconventional activation mechanisms for the TAMs in cancer cells.

A range of human cancer cell lines that overexpress specific TAM RTKs were cultured for this study. Western blot was used to detect protein expression and phosphorylation. The TAM ligand Gas6 rapidly stimulated Axl phosphorylation within minutes but did not alter Tyro3 phosphorylation. Conversely, the related TAM ligand ProS1 rapidly stimulated Tyro3 phosphorylation but with no effect on Axl. Incubation of cells with the Axl‐selective small molecule inhibitor BGB324 led to a blockade of not only basal Axl activity, but also Tyro3 phosphorylation, suggesting that Tyro3 may be activated through a heterodimeric interaction with Axl. This interaction was confirmed by coimmunoprecipitation of Axl‐Tyro3 complexes from cell lysates, which was further strengthened by Gas6 stimulation. In addition, we found that Tyro3 protein stability was dependent on Axl co‐expression, as Axl siRNA knockdown reduced presence of cellular Tyro3 protein but not its mRNA. This suggests the Axl‐Tyro3 heterodimerization stabilizes Tyro3 presence at the cell surface. Furthermore, siRNA knockdown of Tyro3 in cells revealed that Tyro3 functions as a mediator of signaling for cell survival and cell cycle progression through regulation of cyclin D1 – a role distinct from the known proinvasion role of Axl.

Based on these findings, we propose that Tyro3 may be a driver of tumor persistence and chemoresistance through association with Axl and potentially other RTKs. Our current work is further revealing the divergence of downstream signaling pathways to emanate from TAM RTKs activated in different ways, and how these regulate the major cellular behaviors during tumor progression and spread.

Support or Funding Information

This research is funded by the University of Portsmouth and by the Council for At‐Risk Academics (Cara).

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Reconstitution of RNA polymerase I Upstream Activating Factor and the roles of histones H3 and H4 in complex assembly
Authors: Knutson Bruce A , Smith Marissa L , Cui Weidong , Jackobel Ashleigh J , Walker‐Kopp Nancy A
Published: June 2021

RNA polymerase I (Pol I) transcription in Saccharomyces cerevisiae requires four separate factors that recruit Pol I to the promoter to form a pre‐initiation complex (PIC). Upstream Activating Factor (UAF) is one of two multi‐subunit complexes that regulate PIC formation by binding to the ribosomal DNA promoter and by stimulating recruitment of downstream Pol I factors. UAF is composed of Rrn9, Rrn5, Rrn10, Uaf30, and histones H3 and H4. We developed a recombinant E. coli based system to coexpress and purify transcriptionally active UAF complex and to investigate the importance of each subunit in complex formation. We found that no single subunit is required for UAF assembly, including histones H3 and H4. We also demonstrate that histone H3 is able to interact with each UAF‐specific subunit, and show that there are at least two copies of histone H3 and one copy of H4 present in the complex. Together, our results provide a new model suggesting that UAF contains a hybrid H3‐ H4 tetramer‐like subcomplex.

Support or Funding Information

The work was supported by B.A.K. grants from the US National Institutes of Health (NIH) NCI (5K22CA184235), a Sinsheimer Scholar award from the Alexandrine and Alexander L. Sinsheimer Fund, Central New York Community Foundation, Joseph C. George Fund, and Virginia Simons & Dr. C. Adele Brown Fund. Native MS measurements were financed by the NIH NIGMS (P41 GM103422).

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Who perceives they're smarter? Exploring the influence of student characteristics on student academic self‐concept in physiology
Authors: Brownell Sara , Cooper Katelyn , Krieg Anna
Published: June 2021

Academic self‐concept is one's perception of his or her ability in an academic domain and is formed by comparing oneself to other students. As college biology classrooms transition from lecturing to active learning, students interact more with each other and are likely comparing themselves more to other students in the class. Student characteristics can impact students' academic self‐concept, however this has been unexplored in the context of undergraduate biology. In this study, we explored whether student characteristics can affect academic self‐concept in the context of an active‐learning college physiology course. Using a survey, students self‐reported how smart they perceived themselves in the context of physiology relative to the whole class and relative to their groupmate‐ the student they worked most closely with in class. Using linear regression, we found that males and native English speakers had significantly higher academic self‐concept relative to the whole class compared with females and non‐native English speakers. Using logistic regression, we found that males had significantly higher academic self‐concept relative to their groupmate compared with females. Using constant comparison methods, we identified nine factors that students reported influenced how they determined whether they are more or less smart than their groupmate. Finally, we found that students were more likely to report participating more than their groupmate if they had a higher academic self‐concept. These findings suggest that student characteristics can influence students' academic self‐concept, which in turn may influence their participation in small group discussion and their academic achievement in active learning classes.

Support or Funding Information

NONE

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Endothelin‐1 Receptor Responses in Overweight Women
Authors: Nathaniel Sangeetha , Kuczmarski Andrew V. , Haigh Katherine , Wenner Megan M.
Published: June 2021

Increased adiposity is associated with endothelial dysfunction, and contributes to an increased risk of cardiovascular disease. Endothelin‐1 (ET‐1), a potent vasoconstrictor, has been associated with the reduction in endothelium‐dependent vasodilation in overweight and obese adults via the ETA receptor. However, ETB receptors can elicit vasodilation, and have been shown to be important for maintaining vascular health in women. Therefore, the purpose of this study was to test the hypothesis that impaired endothelial function is mediated in part by loss of ETB receptor mediated dilation in overweight women compared with women of normal weight. We tested 8 young normal weight women (22±2 years, BMI 21±1 kg/m2) and 6 young overweight women (21±1 years, BMI 27±1 kg/m2). We measured the vasodilatory responses in the cutaneous circulation using laser Doppler flowmetry during microdialysis perfusions of lactated Ringer's (Control), ETB receptor antagonist (BQ‐788, 300nM), and ETA receptor antagonist (BQ‐123, 500 nM). We utilized local skin heating (42°C) to induce vasodilation, followed by increase in heat (43°C) and perfusion of sodium nitroprusside (28mM) to elicit maximal dilation. Overweight women had impaired vasodilation compared to normal weight women (94±2 vs. 87±3 %max CVC; P=0.05). ETB receptor blockade tended to reduce vasodilation in normal weight women (Control: 94±2 vs. BQ‐788: 89±3 %max CVC; P=0.06) but not in overweight women (Control: 87±3 vs. BQ‐788: 87±3 %max CVC). ETA receptor blockade did not alter blood flow responses in either normal (BQ‐123: 91±2) or overweight young women (BQ‐123: 87±2). These preliminary results suggest that young overweight women have impaired vasodilatory function, possibly related to altered ETB mediated dilation.

Support or Funding Information

NIH Grant P20 GM 103446, U54 GM 104941, P20 GM 113125 and University of Delaware Research Foundation.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Role of viral RNA in virion stability and disassembly
Authors: Anand Ganesh , Lim Xin Xiang , Ramesh Ranita , Raghuvamsi Palur Venkata
Published: June 2021

Viruses are metastable macromolecular entities that are assembled into compact particles. Entry into a target host cell initiates quaternary conformational changes in response to distinct host‐specific environmental changes including temperature, pH, osmolality, divalent cation concentrations, which promote disassembly and release of the virion's genome into the host cell. This host stimulus‐triggered disassembly is critical for initiating the infectious phase of the particle. How viruses use their quaternary coat protein structures as thermodynamic sensors for detecting entry into a conducive host cell environment is largely unknown. The process of viral disassembly is largely impervious to static structural methods as these only capture end‐state conformations. Amide Hydrogen Deuterium Exchange Mass Spectrometry (HDXMS) can be used to monitor whole viral particle dynamics in solution. The disassembling virion represents the virus at its most vulnerable state and is consequently a transient dynamic intermediate. A map of the quaternary structural changes in this state offers critical insights into cryptic epitopes as novel vaccine targets. Our research has pioneered structural mass spectrometry characterization of temperature and divalent cation‐dependent conformational changes on Dengue virus and Turnip Crinkle Virus (TCV) and mapped the specific disassembly processes in these two model virus systems. We have extended these studies to deconstruct the whole viral particle‐antibody (DENV2‐2D22) complex. Our results reveal the high intrinsic dynamics of the RNA packing capsid C‐protein which underpins viral transition from compact to expanded states in the process of disassembly. We have also uncovered new disassembly intermediates triggered by varying monovalent and divalent cation concentrations. Viral disassembly processes in TCV and Dengue reveal conformations of disassembly intermediates which represent powerful new targets for therapeutic antibody design as well as offer fundamental insights into strategically timed viral disassembly processes which can be extended to all viruses.

Support or Funding Information

Singapore Ministry of Education Tier 3 grant

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Cerebral autoregulation during exposure to artificial gravity
Authors: Sanjana Faria , Knox Allan , Falvo Michael , Evans Joyce , Knapp Charles , Serrador Jorge
Published: June 2021

Our work has previously shown that exposure to artificial gravity (AG) can improve orthostatic tolerance. The purpose of this work is to examine whether cerebral autoregulation is improved with AG in twelve hypovolemic men and women. The protocol consisted of an initial ~45 minutes of a “step up” tolerance period, used to determine participants' presyncopal limit, followed by ~45 minutes training period at GZ below participants presyncopal limit. Beat‐by‐beat blood pressure (Portapres), heart rate (ECG), middle cerebral artery blood flow velocity (Transcranial Doppler) and end‐tidal carbon dioxide (capnography) were collected on participants during short arm centrifugation. Cerebral autoregulation was assessed using transfer function analysis between mean arterial pressure (MAP) and mean cerebral blood flow velocity (MCBFV) in 3‐min intervals during the training period. Exposure to AG resulted in a significant positive correlation between GZ and MAP, MAP variability and MCBFV variability in the low frequency (LF) range (0.07–0.15 Hz). In addition, coherence between MAP and MCBFV in the LF range was positively correlated. There was no change in gain and phase between MAP and MCBFV in the same frequency range. With higher GZ, there was a significant positive correlation in coherence and significant negative correlation in gain between MAP and MCBFV in the very low frequency range (0.03–0.07 Hz). These data suggest that increasing GZ exposure is correlated to increasing MAP variability. However, despite this increased MAP variability gain values demonstrated a negative correlation with GZ, suggesting that cerebral autoregulation tended to improve with increasing GZ exposure. We expect increased coherence was a result of the increased MAP variability associated with higher GZ. These data may suggest that exposure to AG may be helpful to improve cerebral autoregulation. Therefore, one could speculate that AG may be a useful tool to consider as a countermeasure for post‐flight astronauts to improve their orthostatic tolerance as well as cerebral autoregulation and improve re‐adaptation to a gravity environment.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Inhibition of Medial Preoptic Area Improves Physical Performance in Trained Rats
Authors: Müller‐Ribeiro Flávia Camargos , Wanner Samuel Penna , Drummond Lucas , Campos Helton Oliveira , Coimbra Candido Celso
Published: June 2021

The medial preoptic area (MPO) plays a key role in the regulation of autonomic thermoeffectors and this area seems to be more activated after physical training, as evidenced by greater number of exercise‐induced c‐Fos immunoreactive neurons in trained rats. This observation raised the question as to whether inhibition of MPO can affect physical performance and thermoregulatory responses in trained rats. Following 2 weeks of high‐intensity interval training (HIIT), Wistar rats were submitted to an incremental‐speed exercise on a motor‐driven treadmill until fatigue after bilateral microinjection of muscimol (80 pmol/100 nl) to evaluate their aerobic capacity and thermoregulatory responses. The core body temperature (Tc) and the maximal oxygen uptake (VO2 max) were recorded continuously during exercise. Physical training increased the time to fatigue (43 ± 2 min vs. 64 ± 2 min; p=0.0009; n=6); the maximum speed attained during the incremental exercise (24 ± 1 m/min vs. 31 ± 1 m/min; p=0.0013), the distance traveled (675 ± 36 m vs. 1261 ± 68 m; p=0.0008); and resulted in a higher oxygen uptake (38 ± 1 ml/min/kg vs. 42 ± 1 ml/min/kg; p=0.01). Interestingly, at fatigue, no difference in the absolute Tc was found between the groups (38.28 ± 0.2 °C vs. 38.78 ± 0.1 °C; p=0.1). Bilateral blockade of MPO using muscimol improved physical performance, as observed by the increased time to fatigue (71 ± 6 min muscimol vs. 58 ± 2 min ‐ control, p=0.004; n=3); distance traveled (1528 ± 188 m muscimol vs. 1094 ± 84 m control; p=0.05); and maximum oxygen uptake (49 ± 1 ml/min/kg muscimol vs. 44 ± 2 ml/min/kg control; p=0.04). Regarding the thermoregulatory adjustments, MPO inhibition tended to increase Tc at fatigue (40.37 ± 0.5 °C muscimol vs. 39.35 ± 0.2 °C ‐ control; p=0.08). There was an increase in the Tc of the control animals during exercise but this temperature remained lower than that of the muscimol group (p<0.001). Our findings show that neurons in the MPO are involved in the control of the aerobic capacity of trained rats, however, the improved physical performance of these animals caused by MPO inhibition did not result from changes in thermoregulatory adjustments.

Support or Funding Information

Conselho Nacional de Desenvolvimento Científico e Tecnlógico ‐ CNPq; grant 434646/2016‐4

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Microvascular Dysfunction, Inflammation and Tissue Injury in Polymicrobial Sepsis
Authors: Kowalewska Paulina M , Ellis Christopher G
Published: June 2021

Sepsis is an overwhelming systemic inflammatory response to infection that may lead to multiple organ failure and shock. One of the characteristics of sepsis is early microvascular dysfunction. In our rat model of polymicrobial sepsis, microvascular dysfunction is detected as early as 3 hours after infection (Bateman et al., Am J Physiol Heart Circ Physiol, 2001). The objective of this study was to examine the timing of microvascular dysfunction in the context of tissue injury and inflammation. Sepsis was induced in male Sprague‐Dawley rats with an intraperitoneal injection of a fecal slurry. Control animals were injected with normal saline. The septic and control animals were then prepared for intravital video microscopy (IVVM) of the right extensor digitorum longus (EDL) muscle. The microvasculature was examined for changes in hemodynamics and erythrocyte oxygen saturation using dual wavelength IVVM for a period of 4 or 6 hours after the injection of the fecal slurry. The data were set aside for future analysis and comparisons were made to our existing hemodynamic data in order to further characterize our sepsis model. Completion of IVVM observations was followed by perfusion fixation and organ collection. Hematoxylin and eosin‐stained sections were graded for pathological and inflammatory changes normalized to tissues collected from naïve control animals. Livers from septic and control animals were both marked by mild leukocyte infiltration in the 4‐hour and 6‐ hour groups, while erythrocyte trapping within the microvasculature did not rise above naïve levels and parenchymal cell architecture was not altered. The EDL muscles from septic animals did not exhibit increased inflammatory cell infiltration. Immunohistochemical labelling of brain sections for rat MHC class II did not show signs of inflammatory microglial activation in coronal slices spanning the entire brain in the septic animals from the 4‐hour and 6‐hour groups. Intravenous injection of Evans Blue prior to perfusion fixation also indicated that the blood‐brain barrier was not broken. On the other hand, septic rats had evidence of increased dye leakage in the liver and kidneys, which was not observed in the saline‐injected animals. Evans Blue leakage was not observed in the intact EDL muscles of either group. The findings of this study suggest that microvascular dysfunction occurs before detectable organ injury in our rat fecal‐induced peritonitis model of sepsis.

Support or Funding Information

Collaborative Health Research Projects ( CHRP )

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
xCDxCDx‐PHD, a distinct type of PHD‐finger
Authors: Basu Shraddha , Boamah Daniel , Poppinga Franchesca AnneMarie , Lin Tao , Chakravarty Suvobrata
Published: June 2021

Plant homeodomain (PHD) scaffolds are conserved protein modules in eukaryotes that typically recognize unstructured histone tails, and thus, play a critical role in chromatin signaling. Being a zinc‐finger, the sequences of PHD‐fingers, since their origin, have diverged. However, certain sequence signature features in PHD‐finger sequences suggest that there could be different subtypes among PHD‐fingers. One such subtype is the PHD‐finger featuring the xCDxCDx motif in the treble clef. Even though PHD‐finger binding‐site is rich in negatively charged residues for interacting with positively charged histone proteins, we note that a number of nonpolar amino acids are enriched at the binding site of xCDxCDx‐PHD subtype. These nonpolar residues have likely coevolved with the xCDxCDx motif. In general, coevolving residues contribute to: (a) folding of a scaffold, and/or (b) function (e.g., substrate binding). Here, we probed the coevolving residues of xCDxCDx‐PHD to find which of the two contributions (a or b or both) do they make. We have learned that the coevolving residue of xCDxCDx‐PHD are necessary for peptide binding and contribute little toward folding of xCDxCDx‐PHD scaffold.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Cerebral Autoregulation and Cerebrovascular Reactivity is Similar in African American And Caucasian Males Despite Different Blood Pressures and Anterior Cerebral Artery Flow Velocities
Authors: Knox Allan , Favre Michelle , Haber Yaa , Falvo Michael , Serrador Jorge
Published: June 2021

Cerebral autoregulation maintains adequate cerebral perfusion over varying systemic blood pressures, with any dysfunction giving opportunity for cerebral insult. African American (AA) males experience higher prevalences of hypertension and cerebrovascular abnormalities than their Caucasian (CAUC) counterparts. Potential racial differences in cerebral autoregulation may contribute to the high incidences of cerebrovascular events suffered by AA males. Therefore, the purpose of this investigation was to determine cerebral autoregulation and flow velocities of the cerebral circulation in AA and CAUC males. Cross‐sectional data of beat‐by‐beat blood pressure (BP), end‐tidal CO2 (ETCO2) middle cerebral artery (MCA) and anterior cerebral artery (ACA) velocities, cerebrovascular reactivity (CVR), and cerebral autoregulation was determined at the very low frequency (VLF: 0.03–0.07 Hz) and low frequency (LF: 0.07–0.15 Hz) domains in sample of AA (n=30, 44.91 ± 12.04 years) and CAUC (n=51, 44.48 ± 12.71 years, p=0.879) males. Mean BP was higher in AAs (96.25 ± 14.34 mmHg) than CAUCs (88.39 ± 11.93 mmHg, p=0.015). Systolic BP was elevated in AAs (137.64 ± 20.39 mmHg) compared to CAUCs (128.52 ± 16.65, p=0.037), with the same trend seen with diastolic BP (AA: 77.53 ± 12.81 mmHg; CAUC: 70.49 ± 11.31 mmHg, p=0.021). ETCO2 and CVR was comparable between groups (p=0.351 and p=0.290, respectively). Cerebral autoregulation was similar between groups in the MCA at the VLF (Coherence: p=0.184, Gain: p= 0.748, Phase: p=0.841) and LF (Coherence: p=0.683, Gain: p=0.800, Phase: p=0.178) domains. Cerebral autoregulation was also proportionate in the ACA at the VLF (Coherence: p=0.360, Gain: p=0.266, Phase: p=0.231) and LF (Coherence: p=0.293, Gain: p=0.530, Phase: p=0.360) domain. Autoregulation index at the MCA and ACA was comparable between groups (p=0.358 and p=0.620, respectively). MCA mean flow velocity was similar between groups (p=0.814), although ACA mean flow velocity was higher in AAs (52.17 ± 8.89 ml/cm/s) compared to CAUCs (44.02 ± 11.19 ml/cm/s, p=0.013). The current data demonstrate comparable levels of cerebral autoregulation in AA and CAUC males, despite differing systemic BP and ACA velocities. This proposes that cerebral autoregulation is intact within AA males and may not contribute to the increased prevalence of cerebrovascular insults shown in current epidemiological data. Future studies are warranted to include larger sample sizes in addition to absolute cerebral blood flow measures to confirm these findings.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The effects of localized heating on insulin‐stimulated leg blood flow
Authors: Walsh Lauren , Manrique‐Acevedo Camila , Martinez‐Lemus Luis , Padilla Jaume
Published: June 2021

Vasodilator actions of insulin contribute to glucose disposal in skeletal muscle. Previous studies have shown that increased physical activity, or even a single bout of leg exercise, improves insulin‐stimulated leg blood flow; however, the mechanisms by which exercise mediates this apparent improvement in vascular insulin sensitivity remain largely unknown. Herein we tested the hypothesis that increased limb blood flow‐induced shear stress primes the vasculature to become more insulin‐sensitive. Eleven young healthy subjects (eight men, three women) underwent one‐hour of single‐leg heating (limb immersion in a 40–42°C water bath) to increase blood flow, while the contralateral leg remained outside of the water bath serving as a non‐heated internal control. The heating was followed by a 60‐minute cooldown. Thereafter, bilateral measures of popliteal artery blood flow (via Doppler ultrasound) were performed at baseline and at 45 and 60 minutes during systemic infusion of insulin to mimic postprandial levels. Dextrose was co‐infused at varying rates to maintain euglycemia. As expected, 60 minutes of leg heating increased popliteal artery blood flow by ~3‐fold, relative to the non‐heated control leg. Leg blood flow returned to basal levels following cooldown. Consistent with the hypothesis, popliteal artery blood flow was significantly elevated after 45 minutes, but not 60 minutes, of insulin infusion in the previously heated leg; whereas no significant changes were noted in the control leg throughout. These preliminary results indicate that one‐hour of single‐leg heating improves insulin‐stimulated popliteal artery blood flow, supporting the notion that increased blood flow‐induced shear stress sensitizes the vasculature to the actions of insulin. Additional experiments are underway to confirm these findings.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Myocardial Impairments Rather Than Rhythm Status Contributes to Exercise Intolerance in Patients with Atrial Fibrillation
Authors: Elliott Adrian , Verdicchio Christian , Gallagher Celine , Linz Dominik , Mahajan Rajiv , Sanders Prashanthan
Published: June 2021

Background

Exercise intolerance is commonly reported in patients with atrial fibrillation (AF) despite preserved ejection fraction. However, the contribution of rhythm, echocardiographic parameters and cardiovascular risk factors to exercise intolerance is poorly understood. Furthermore, recent data shows a high prevalence of heart failure with preserved ejection fraction amongst AF patients, which may contribute to exercise intolerance. Our aim was to evaluate the prevalence of exercise intolerance and its potential contributors amongst a cohort of AF patients undergoing cardiopulmonary exercise testing (CPET).

Methods

We assessed 151 AF patients (34% female) referred for CPET. All patients underwent routine clinical assessment, including detailed evaluation of cardiovascular risk factors, transthoracic echocardiography and a maximal CPET using a modified Balke treadmill protocol. To investigate the contribute of cardiac rhythm to exercise tolerance, CPET was reported in a select cohort of patients with persistent AF, 21 days following electrical cardioversion to sinus rhythm (SR).

Results

The mean age was 67±8 years with a BMI of 29.4±4.4 Kg/m2. 59% of the cohort were in sinus rhythm (SR) at the time of testing. 41% of patients reached a peak VO2 <85% of age and gender predicted values. There was no significant difference in peak VO2 between patients in AF versus SR (p=0.22). After adjustment for age and gender, only chronotropic response (p=0.017) and echocardiographic indices of left ventricular (LV) filling pressures (E/E′, p=0.014) were significant predictors of peak VO2. In 20 patients who underwent subsequent cardioversion from AF to SR, peak VO2 improved significantly from 19.7±7.0 to 21.4±6.1 ml/kg/min (p=0.003).

Conclusion

Our main findings are that (i) the main predictors of peak VO2 are chronotropic response to exercise and indices of LV filling pressure, (ii) peak VO2 can be significantly improved in patients with persistent AF by restoration of SR. These findings highlight potential targets alongside rhythm control, for the improvement of exercise tolerance in AF patients.

Support or Funding Information

National Heart Foundation of Australia Postdoctoral Fellowship

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The promoting role of hnRNPK‐DDX3 interaction in the apoptosis upon DNA damage
Authors: Chen Chiao‐Che , Yang Jen‐Hao , Lin Chao‐Hsiung
Published: June 2021

Heterogeneous nuclear ribonucleoprotein K (hnRNPK) is an RNA/DNA binding protein that participates in multiple cell functions due to its functional domains. In addition, some of its post‐translational modifications (PTMs) are critical for functions of hnRNPK. Importance of hnRNPK in cancers has been implied by its strong correlation with cancer transformation, progression and migration, but the mechanism how hnRNPK promotes cancer remains ambiguous. Our previous study reported that arginine methylation of hnRNPK negatively regulates U2OS cell apoptosis upon DNA damage. Recently, we showed that DDX3 helicase is a molecular partner of hnRNPK and may be involved in the hnRNPK‐mediated apoptosis upon DNA damage. In this study, we further investigated the role of DDX3 activity in the apoptosis regulation of U2OS cells using a DDX3 inhibitor. Interestingly, this inhibitor not only increased hnRNPK‐mediated apoptosis upon DNA damage but also elevated hnRNPK‐DDX3 interaction during early DNA damage. These results suggests that hnRNK‐DDX3 interaction is important for apoptosis induction by DNA damage. On the other hand, DDX3 has been shown to enhance p53 stabilization during DNA damage. We thus measured the protein level of p53 during treatment of DDX3 inhibitor but found that such treatment decreased both p53 and p21, implying that hnRNK‐DDX3 interaction promotes DNA damage‐induced apoptosis in a p53‐independent manner. In summary, our results suggests that the hnRNPK‐DDX3 interaction is critical for apoptotic regulation upon DNA damage.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Microarray analysis of the PVN of spontaneously hypertensive wistar rats (SHR)
Authors: O'Brien Fiona , Feetham Claire , Barrett‐Jolley Richard
Published: June 2021

The paraventricular nucleus (PVN) of the hypothalamus is a key autonomic regulation area in the brain known to influence sympathetic nerve activity. Identified neurons project from the PVN to the spinal cord and can modulate cardiac function (Coote JH 1995). The PVN has been linked to cardiovascular diseases such as hypertension, where an elevation in sympathetic nerve activity is observed (Guyenet PG 2006 and Zhang K et al. 2002). For example, the activity of ‘spinally projecting’ PVN neurons is altered in models of heart failure (Patel KP 2000) and lesioning of the PVN prevents the development of spontaneous hypertension in SHRs (Takeda K et al. 1991).

In this study, we performed transcriptome analysis of tissue from the PVN of 4 SHR and 4 normal Wistar Kyoto rats. In brief, tissue was isolated by 2mm diameter tissue punch from the dorsal PVN, homogenised and RNA extracted with Qiagen RNAeasy minikits in accordance with the manufactures instructions. The highest quality scoring 3 normal and 3 SHR were then analysed with an Illumina Beadchip microarray. Data was analysed in MatLab. Log2 normalised expression sets were created and genes with low absolute expression values or variance were filtered out (lowest 10%) (Kohane, I. et al. 2003). Significant differential transcription was then identified with an all permutation (t‐test). FDR and correct “q‐values” were created following the methods of Storey et al. 2003. Significantly increased/decreased genes were subjected to biological function enrichment analysis using PANTHER.

Both PCA (PC1 vs PC2) and cluster analysis showed complete separation of the SHR and normotensive populations and 1592 genes in total were differentially expressed by more than 1.3 fold (and q‐value<0.05). Of particular interest to autonomic control of cardiovascular function was the enriched clusters of genes associated with circulatory control (AVP, angiotensin and Substance P, and the α‐1B adrenergic receptor), however, some genes associated with “inflammaging” were also differentially expressed such as superoxide dismutase 1 enzyme (SOD) and Il1b.

Our results illustrate that there are distinct PVN‐specific changes in gene expression that occur in spontaneously hypertensive rats. In particular, we show that genes important in circulatory control and fear/stress responses are enriched in the PVN, further supporting a role for the PVN in cardiovascular diseases. Further experiments are needed to verify the functionality of these changes in gene expression, such as brain‐slice electrophysiology and whole‐animal experiments. The results of these experiments will be crucial in understanding the role of PVN in cardiovascular diseases such as hypertension.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Cellular Senescence in Primary Muscle Fibroblasts is Associated with Changes in Extracellular Matrix Remodeling
Authors: Judge Jennifer L , Brooks Susan V
Published: June 2021

Background

Advanced aging leads increased stiffness of the skeletal muscle extracellular matrix (ECM), which is associated with declines in skeletal muscle function and mass. Previous work by our group has shown increased stiffness of the ECM is associated with changes in ECM modification (hydroxyproline content, advanced glycation end products), without changes in total ECM area in aged mouse muscle tissue (Wood et al., 2014). Here we investigated whether changes in ECM modification with age are the result of cellular senescence in muscle fibroblasts, which play an active role in ECM production and modification. We hypothesize that muscle fibroblasts become senescent with advanced age, and that cellular senescence is associated with altered ECM modification that could lead to stiffness.

Methods

Hindlimb muscles from 3–4 month old C57Bl/6 mice were digested in collagenase and primary fibroblasts were cultured and used between passages 3–5. Cells were confirmed to fibrogenic by expression of Tcf4 and absence of MyoD. Cellular senescence was induced using 200 μM hydrogen peroxide (H2O2) for 2 hours. RNA was collected after 72 hours to assess cellular senescence, and changes in collagen and ECM modification transcripts by quantitative PCR. Cellular senescence was evaluated by senescence associated beta‐galactosidase staining.

Results

H2O2 resulted in positive beta‐galactosidase staining, suggesting cellular senescence. H2O2 also increased mRNA transcripts associated with cellular senescence: p16 and p21. Fibrillar collagen 1α1 and 3α1 transcripts were unchanged, while non‐fibrillar collagen 4α1 was increased with H2O2. Prolyl 4 hydroxylase, an important enzyme in collagen fiber synthesis, was increased, as was tissue inhibitor of metalloproteinases (TIMP) 1 and 2. Matrix metalloproteinase 2 levels were unchanged.

Conclusions

Induced cellular senescence with H2O2 in muscle fibroblasts demonstrated changes in mRNA transcripts that promote collagen synthesis (prolyl 4 hydroxylase) and inhibit matrix degradation (TIMP 1 and 2) without changing de novo fibrillar collagen transcripts. These results suggest that muscle fibroblast senescence may be a cellular mechanism that leads to increased stiffness in ECM through changes in matrix modification and processing.

Support or Funding Information

This work was supported by K12GM111725 and AG051442.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Activation of Growth Signaling in Skeletal Muscle by Growth Arrest Specific‐6
Authors: Wyson Brenna M. , Matsumura Marc S. , Deyle Michael R. , Knowlton M. Nekel , Arroyo Juan A. , Hyldahl Robert D. , Thomson David M.
Published: June 2021

Growth‐arrest specific protein 6 (Gas6) is believed to be involved in activation of cell proliferation and growth of many tissues through its activation of the Akt and MAPK signaling pathways downstream of its primary tyrosine kinase receptor, Axl. Currently the role of Gas6 in skeletal muscle has not been elucidated. The purpose of this study was to determine whether skeletal muscle is responsive to Gas6 stimulation. To do this C2C12 myoblasts were incubated in 100 ng/ml of recombinant mouse Gas6 for 15–180 minutes. Gas6 treatment increased Akt phosphorylation, which peaked at 30–60 minutes. We identified Axl expression via immunofluorescence in rat tibialis anterior muscles. Next, soleus (SOL) and plantaris (PLT) muscle strips from 10–12 week old Lewis rats were incubated with or without 200 ng/ml of Gas6 for 30 minutes. Gas6 failed to increase Akt or Erk phosphorylation in slow‐twitch SOL muscles, but increased Erk phosphorylation (but not Akt) in fast‐twitch PLT muscles. We conclude that Gas6 activates Akt or Erk signaling in myoblasts and mature muscle respectively. This suggests that Gas6 may potentially regulate regeneration and/or growth as well as many other cellular processes in skeletal muscle.

Support or Funding Information

BYU Gerontology Program Grant

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Differential Diagnosis of pancreatic ductal adenocarcinoma based on differential expression of select miRNA in pancreatic tissue and plasma
Authors: Figueiredo Rafael Zimak , Vieira Nivaldo Farias , Cirino Mucio Luiz Assis , Neto Fermino Sanches Lizarte , Gaspar Alberto Facury , da Cunha Tirapelli Daniela Pretti , Sankarankutty Ajith Kumar , Kemp Rafael , dos Santos José Sebastião
Published: June 2021

The differential diagnosis, treatment and prognosis of pancreatic ductal adenocarcinoma (PA) are still a challenge in clinical practice. The aim of the current study was to assess the role of select plasma and tissue microRNAs (miRs‐21, ‐23a, ‐100, ‐107, ‐181c e ‐210) as biomarkers for the diagnosis of PDCA. Samples of plasma (PAp Group, n=13), pancreatic tumors (PAt Group, n=18) and peritumoral regions (PPT Group, n=9) were collected from patients during the surgical procedure. The control group consisted of samples collected from patients submitted to pancreatic surgery for trauma or from cadaveric organ donors (PC Group, n=7). Healthy volunteers donated blood for plasma collection (PCp Group, n=6). The relative abundance of six miRNAs was measured in all groups using real‐time PCR, and serum CA 19‐9 levels were determined in Groups PA and PC, with the difference being considered significant when p <0.05. In tissue samples, there was a difference in the expression of miRNA‐21 (p=0.005) and miRNA‐210 (p=0.008) across the PAt, PC and PPT groups; miRNA‐21 distinguished group PAt from PC and PPT and miRNA‐210 distinguished group PAt from PC. Serum CA 19‐9 showed 88% accuracy (ROC‐AUC 0.95; 0.84 – 1), 83% sensitivity, and 100% specificity at a cut‐off of 37 ng/dl. The PAp group showed overexpression of miR‐181c (95% CI1.67 – 17.68; p<0.00001) and miR‐210 (95% CI0.16 – 5,20; p=0.03) compared to the PCp group. The combination of tissue expression of miR‐21, ‐210 and serum CA 19‐9 showed 100% accuracy for the diagnosis of PA, and the accuracy of plasma miR‐181c (PAp × PCp) was also 100%. These findings suggest that the combination of tissue miRNAs and serum CA 19‐9 can improve accuracy, but plasma miRNA expression can be used as a noninvasive diagnostic test for PA, although further studies are necessary to validate these results as well as to evaluate the utility of miRNA expression as a biomarker related to survival and to the response to therapy in PA.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.