B.A. 1983, Cornell University, Ithaca, NY
Ph.D. 1988, University of Colorado Health Sciences Center
Postdoctoral Fellow, Colorado State University, Bolder, CO
Intracellular calcium concentration is crucial in controlling many aspects of neuronal function including regulation of neurotransmitter release and activation/inactivation of various genes and enzymes. One of the main sources of increasing calcium concentration is by influx through calcium channels that open in response to changes in voltage (voltage dependent calcium channels). Thus, modulation of calcium channels is a prime mechanism by which neurotransmitters can regulate neuronal function. The main interest in my laboratory is in the modulation of these channels. More specifically, the current research program is investigating the mechanisms and functional significance of GABAB receptor modulation of voltage dependent calcium channels in the hippocampal brain region. GABA (γ-aminobutyric acid) is the main inhibitory neurotransmitter in the mammalian brain. Pharmaceutical compounds that interact with receptors for GABA such as barbiturates and valium, are routinely prescribed for anxiety, epilepsy, insomnia, etc. Unfortunately, these types of pharmaceutical compounds interact with most inhibitory synapses making side effects, such as drowsiness, fatigue, mental slowing, and double vision common. By increasing our understanding of the specific effects of GABA, it will be possible to design better pharmaceutical agents for a particular disorder.
Studies in our laboratory have demonstrated that GABA attenuates N-type calcium current (CaV2.2) and facilitates L-type calcium current (CaV1.2, and/or 1.3) by activation of GABAB receptors in the early neonatal period in the superior region of rat hippocampus. The facilitation of L-type current is a novel finding not previously demonstrated in the mammalian central nervous system and this effect peaks in the first postnatal week. This facilitation coincides with the developmental up-regulation of K+Cl- co-transporter (KCC2) expression in hippocampal neurons. We have demonstrated that this increase in KCC2 expression is dependent on influx of calcium through L-type channels giving support for a role of L-type calcium channels in regulating gene expression during development. We have determined that protein kinase C activation is necessary for the enhancement of L-type current in neonatal hippocampus and are now investigating other potential components of the pathway. A combination of whole cell patch clamp recording and ratiometric calcium imaging in acutely dissociated hippocampal neurons is being utilized to isolate various components of the pathway pharmacologically or through knockdown experiments. Western blot analysis and confocal imaging has been utilized to study the developmental expression of the L-type calcium channel isoforms and co-localization of the channels with GABAB receptors.
Kramer, A.A., Ingraham, N.E., Sharpe, E.J., and Mynlieff, M. 2012. Journal of Signal Transduction, vol. 2012, Article ID 597214, 11 pages, 2012. doi:10.1155/2012/597214
Bray, J.G. and Mynlieff, M. 2011. Involvement of protein kinase C and protein kinase A in the enhancement of L-type calcium current by GABAB receptor activation in neonatal hippocampus. Neuroscience, 179, 62-72.
Bray, J.G. and Mynlieff, M. 2009. Influx of calcium through L-type calcium channels in early postnatal regulation of chloride transporters in rat hippocampus. Developmental Neurobiology, 69(13), 885-896.
Carter, T.J. and Mynlieff, M. 2004. GABAB receptors facilitate L-type and attenuate N-type Ca2+ currents in isolated hippocampal neurons. Journal of Neuroscience Research, 76(3), 323-33.
Carter, J.R. and M. Mynlieff. 2003. Amyotrophic lateral sclerosis patient IgG alters voltage-dependence of Ca2+ channels in dissociated rat motoneurons. Neuroscience Letters, 353(3), 221-5.McCallum, J.B.
A.S. Karls and Mynlieff, M. CaMKII is not a component of the signal transduction pathway mediating GABAB receptor enhancement of L-type calcium current in neonatal rat hippocampus. Society for Neuroscience, 37, 2011.
E.J. Sharpe and Mynlieff, M. CaV1.3 but not CaV1.2 L-type calcium channels co-localize with GABAB receptors in neonatal rat hippocampus. Society for Neuroscience, 37, 2011.
N.E. Ingraham and Mynlieff, M. Changes in steady-state expression of CaV1.2 and CaV1.3 L-type calcium channels through development in the postnatal rat hippocampus. Society for Neuroscience, 36, 2010
J.G. Bray and Mynlieff, M. PKC and Possibly PKA are involved in the Signal Transduction Mechanism of L-type Calcium Current Facilitation by GABAB Receptor Activation in the Neonatal Rat Hippocampus. Society for Neuroscience, 36, 2010.
A.S. Karls and Mynlieff, M. GABAB receptor activation leads to changes in the activation voltage of calcium current Society for Neuroscience, 36, 2010.
A.A. Kramer and Mynlieff, M. Localization of CaV1.2 and CaV1.3 L-type calcium channels in the superior region of the neonatal rat hippocampus. Society for Neuroscience, 36, 2010.
National Academies Education Fellow in Life Sciences (2007)
Andrew S. Karls (Ph.D. student)
Emily J. Sharpe (undergraduate)
Joseph F. Kearney (undergraduate)
Nicholas Gillingham (Oberlin College undergraduate)
Dr. Mynlieff is currently accepting new Ph.D. students into her lab
Jennifer R. Carter, 2001, M.S.
Thomas J. Carter, 2002, Ph.D.
Robert L. Keesey, Ph.D., postdoctoral fellow
Jennifer G. Bray, 2010, Ph.D.