Personal HistoryI received a BS in Biochemistry from Yale, completed 2 years of Medical School at Tufts, spent 1 year as a special student in Biophysics and Physiology at University College, London and completed my PhD in Physiology at Duke. After postdoctoral training in Physiology at Yale Medical School, I was a faculty member in the Department of Physiology at the University of Rochester School of Medicine (including a year's sabbatical at the Neurobiology Laboratory, Ecole Normale Superieure, Paris, France) before joining the Biochemistry Department at the School of Medicine.
Calcium ions serve as intracellular messengers for a wide range of cellular functions, spanning time scales ranging from milliseconds to hours, days or even weeks. We are studying the cellular and molecular mechanisms underlying the generation and transduction of several responses mediated by intracellular Ca2+ in skeletal muscle fibers, sympathetic ganglion neurons and in cell culture systems.
Generation of the Ca2+ transient in skeletal muscle:
Skeletal muscle is activated within a few ms after membrane depolarization by a massive release of Ca2+ ions from the intracellular storage location, the sarcoplasmic reticulum. We are studying three steps in the activation mechanism for Ca2+ release in isolated single functioning skeletal muscle fibers: (1) Activation of membrane voltage sensor molecules, studied electrophysiologically by the resulting "gating current" ; (2) Opening patterns of individual Ca2+ release channels or of a group of a few functionally linked release channels in response to depolarization or ligand activation, detected by laser scanning confocal microscopy as highly localized calcium "sparks"; (3) the mechanism coupling the voltage sensors to the release channels, studied by pharmacological and biochemical manipulation in functioning fibers. (supported by NIH/NINDS grant "Excitation-contraction coupling in cut muscle fibers")
Molecular basis of skeletal muscle fiber types:
In another project we are studying the molecular mechanisms underlying functional differences in mammalian fast-twitch and slow-twitch skeletal muscle fibers, which differ in the speed of contraction and relaxation and which express different isoforms of most muscle-specific proteins. The qualitative and quantitative differences in protein expression and how such differences underlie the differences in the generation and transduction of the [Ca2+] transients in the two fiber types is being investigated in muscle fibers acutely isolated from adult muscle and in isolated fast- and slow-twitch fibers maintained in cell culture. (supported by NIH/NINDS grant "Calcium removal and regulation of muscle function")
Calcium signalling in neurons:
Mechanisms of Ca2+ signalling in neurons are being investigated in neurons isolated from sympathetic ganglia and maintained in culture. Topics currently under examination in our lab include mechanisms for terminating the cytosolic [Ca2+] signal and the spatial location of the intracellular store from which Ca2+ ions are released. (supported by NIH/NINDS grant "Calcium removal and regulation of muscle function").
Calcium homeostasis in dystrophic muscle fibers:
The fiber isolation and culture methods developed in our lab (above) are also being used to investigate the basis of differences in calcium homeostasis in muscle fibers isolated from normal and dystrophic mice. Dystrophic mice lack the muscle cytoskeletal protein dystrophin, which is also absent in human Duchenne muscular dystrophy and may provide mechanical support for the muscle fiber membrane. (supported by the Muscular Dystrophy Association).
Lab Techniques and EquipmentCell Biophysics and Physiology: action potentials, voltage clamp, gating current, Ca2+ indicators and global intracellular [Ca2+] transients, laser scanning confocal microscopy of local Ca2+ release events (Ca2+ sparks), computer controlled rapid local cell perfusion. Cell Biology: isolation and culture of adult rat and mouse fast-twitch and slow-twitch skeletal muscle fibers and frog sympathetic ganglion neurons, antibody stain and confocal microscopy. Biochemistry and Molecular Biology: single muscle fiber protein analysis, RTPCR and (in collaboration) heterologous gene and protein expression and reporter gene expression in cultured cell lines and in muscle fibers. Computer Analysis and Mathematical Modelling: multiple parameter curve fitting, modelling the calcium binding and transport systems in neurons and muscle fibers, digital image processing, numerical deblurring of fluorescence microscopic images.
Lisa Brown, Assistant Professor, Morgan State University
Chris Ward, Assistant Professor, UMB School of Nursing
Publications 2009- 2012
Elevated extracellular glucose and uncontrolled type 1 diabetes enhance NFAT5 signaling and disrupt the transverse tubular network in mouse skeletal muscle. Hernández-Ochoa EO, Robison P, Contreras M, Shen T, Zhao Z, Schneider MF. 2012 Exp Biol Med (Maywood). 2012 Sep 10. [Epub ahead of print] PMID: 22500113
Kinetics of nuclear-cytoplasmic translocation of Foxo1 and Foxo3A in adult skeletal muscle fibers Schachter, TN, Shen, T, Liu,Y and Schneider, MF. Am J Physiol, Cell Physiol (2012) in press
NOX2 dependent ROS is required for HDAC5 nuclear efflux and contributes to HDAC4 nuclear efflux during intense repetitive activity of fast skeletal muscle fibers. Liu, Y, Hernández-Ochoa, EO, Randall, WR, and Schneider, MF. (2012) Am J Physiol, Cell Physiol (2012) in press
Voltage clamp methods for the study of membrane currents and SR Ca2+ release in adult skeletal muscle fibers. Hernendez-Ochoa, E.O. and Schneider, M.F. Prog Biophys Mol Biol 2012: 108: 98-118. Review
Localization and regulation of the N terminal splice variant of PGC-1α in adult skeletal muscle fibers. Shen T, Liu Y, Schneider MF. J Biomed Biotechnol. 2012;2012:989263. Epub 2012 Jan 29. PMID: 22500113
Mice null for calsequestrin 1 exhibit deficits in functional performance and sarcoplasmic reticulum calcium handling. Olojo RO, Ziman AP, Hernández-Ochoa EO, Allen PD, Schneider MF, Ward CW. PLoS One. 2011;6(12):e27036. Epub 2011 Dec 2. PMID: 22164205
Adherent primary cultures of mouse intercostal muscle fibers for isolated fiber studies. Robison P, Hernández-Ochoa EO, Schneider MF. J Biomed Biotechnol. 2011;2011:393740. Epub 2011 Aug 16. PMID: 21869860
S100A1 and calmodulin regulation of ryanodine receptor in striated muscle. Prosser BL, Hernández-Ochoa EO, Schneider MF. Cell Calcium. 2011 Oct;50(4):323-31. Epub 2011 Jul 23. Review. PMID: 21784520
Effects of conformational peptide probe DP4 on bidirectional signaling between DHPR and RyR1 calcium channels in voltage-clamped skeletal muscle fibers. Olojo RO, Hernández-Ochoa EO, Ikemoto N, Schneider MF. Biophys J. 2011 May 18;100(10):2367-77. PMID: 21575570
Modulation of sarcoplasmic reticulum Ca2+ release in skeletal muscle expressing ryanodine receptor impaired in regulation by calmodulin and S100A1. Yamaguchi N, Prosser BL, Ghassemi F, Xu L, Pasek DA, Eu JP, Hernández-Ochoa EO, Cannon BR, Wilder PT, Lovering RM, Weber D, Melzer W, Schneider MF, Meissner G. Am J Physiol Cell Physiol. 2011 May;300(5):C998-C1012. Epub 2011 Feb 2. PMID: 21289290
DNA binding sites target nuclear NFATc1 to heterochromatin regions in adult skeletal muscle fibers. Shen T, Liu Y, Contreras M, Hernández-Ochoa EO, Randall WR, Schneider MF. Histochem Cell Biol. 2010 Oct;134(4):387-402. Epub 2010 Sep 24. PMID: 20865272
S100A1 promotes action potential-initiated calcium release flux and force production in skeletal muscle. Prosser BL, Hernández-Ochoa EO, Lovering RM, Andronache Z, Zimmer DB, Melzer W, Schneider MF. Am J Physiol Cell Physiol. 2010 Nov;299(5):C891-902. Epub 2010 Aug 4 PMID: 20686070
Augmentation of Cav1 channel current and action potential duration after uptake of S100A1 in sympathetic ganglion neurons. Hernández-Ochoa EO, Prosser BL, Wright NT, Contreras M, Weber DJ, Schneider MF. Am J Physiol Cell Physiol. 2009 Oct;297(4):C955-70. Epub 2009 Aug 5. PMID: 19657060
The Qgamma component of intra-membrane charge movement is present in mammalian muscle fibres, but suppressed in the absence of S100A1. Prosser BL, Hernández-Ochoa EO, Zimmer DB, Schneider MF. J Physiol. 2009 Sep 15;587(Pt 18):4523-41. Epub 2009 Aug 3. PMID: 19651767
Simultaneous recording of intramembrane charge movement components and calcium release in wild-type and S100A1-/- muscle fibres. Prosser BL, Hernández-Ochoa EO, Zimmer DB, Schneider MF. J Physiol. 2009 Sep 15;587(Pt 18):4543-59. Epub 2009 Aug 3. PMID: 19651766
Alpha-adrenergic signalling activates protein kinase D and causes nuclear efflux of the transcriptional repressor HDAC5 in cultured adult mouse soleus skeletal muscle fibres. Liu Y, Contreras M, Shen T, Randall WR, Schneider MF. J Physiol. 2009 Mar 1;587(Pt 5):1101-15. Epub 2009 Jan 5. PMID: 19124542