Abstract
Focal cortical dysplasia (FCD) is a major cause for drug-resistant epilepsies. The molecular and cellular mechanisms of epileptogenesis in FCD are still poorly understood. Some studies have suggested that deficiencies of γ-aminobutyric acid (GABA) system may play an important role in type II FCD, but it remains controversial. In order to examine whether and how GABAergic interneurons and synaptic function are affected, we generated a somatic mTOR hyperactivation-based mouse model of type II FCD by in utero electroporation, quantified densities of interneurons in the malformed cortices, and recorded miniature inhibitory postsynaptic currents in dysmorphic neurons. We detected 20–25% reduction of GABAergic interneurons within malformed cortices, independent of cortical regions and cell subtypes but proportionate to the decrease of global neuron counts. GABAergic synaptic transmission from interneurons to mTOR hyperactivated dysmorphic neurons was dramatically disrupted, outweighing the decrease of interneuron counts. Postnatal mTOR inhibition partially rescued these alterations of GABAergic system. We also quantified the expression of GABAA receptor, GABA transporter, and chloridion transporter encoding genes and found that their expression was relatively intact within the malformed cortices. Taken together, these results confirmed that GABAergic interneuron and synapse transmission are disturbed profoundly in an mTOR-dependent manner in type II FCD. Our study suggests that postsynaptic mechanisms independent of interneuron reduction or altered expression of GABA synapse genes might be accountable for the impaired GABAergic neurotransmission in type II FCD as well as other mTOR-related epilepsies.
Similar content being viewed by others
Abbreviations
- GABA:
-
γ-Aminobutyric acid
- FCD:
-
Focal cortical dysplasia
- mTOR:
-
Mechanistic target of rapamycin
- mIPSC:
-
Miniature inhibitory postsynaptic current
- IUE:
-
In utero electroporation
- RT-PCR:
-
Real-time polymerase chain reaction
- GFP:
-
Green fluorescent protein
- GAD:
-
Glutamate decarboxylase
- PV:
-
Parvalbumin
- SST:
-
Somatostatin
- CR:
-
Calretinin
References
Blumcke I, Thom M, Aronica E, Armstrong DD, Vinters HV, Palmini A, Jacques TS, Avanzini G et al (2011) The clinicopathologic spectrum of focal cortical dysplasias: a consensus classification proposed by an ad hoc task force of the ILAE Diagnostic Methods Commission. Epilepsia 52(1):158–174. https://doi.org/10.1111/j.1528-1167.2010.02777.x
Blumcke I, Spreafico R, Haaker G, Coras R, Kobow K, Bien CG, Pfafflin M, Elger C et al (2017) Histopathological findings in brain tissue obtained during epilepsy surgery. N Engl J Med 377(17):1648–1656. https://doi.org/10.1056/NEJMoa1703784
Lim JS, Kim WI, Kang HC, Kim SH, Park AH, Park EK, Cho YW, Kim S et al (2015) Brain somatic mutations in MTOR cause focal cortical dysplasia type II leading to intractable epilepsy. Nat Med 21(4):395–400. https://doi.org/10.1038/nm.3824
Jansen LA, Mirzaa GM, Ishak GE, O'Roak BJ, Hiatt JB, Roden WH, Gunter SA, Christian SL et al (2015) PI3K/AKT pathway mutations cause a spectrum of brain malformations from megalencephaly to focal cortical dysplasia. Brain J Neurol 138(Pt 6):1613–1628. https://doi.org/10.1093/brain/awv045
Baldassari S, Ribierre T, Marsan E, Adle-Biassette H, Ferrand-Sorbets S, Bulteau C, Dorison N, Fohlen M et al (2019) Dissecting the genetic basis of focal cortical dysplasia: a large cohort study. Acta Neuropathol 138(6):885–900. https://doi.org/10.1007/s00401-019-02061-5
Baulac S, Ishida S, Marsan E, Miquel C, Biraben A, Nguyen DK, Nordli D, Cossette P et al (2015) Familial focal epilepsy with focal cortical dysplasia due to DEPDC5 mutations. Ann Neurol 77(4):675–683. https://doi.org/10.1002/ana.24368
Ljungberg MC, Bhattacharjee MB, Lu Y, Armstrong DL, Yoshor D, Swann JW, Sheldon M, D'Arcangelo G (2006) Activation of mammalian target of rapamycin in cytomegalic neurons of human cortical dysplasia. Ann Neurol 60(4):420–429. https://doi.org/10.1002/ana.20949
Crino PB (2015) mTOR signaling in epilepsy: insights from malformations of cortical development. Cold Spring Harb Perspect Med 5(4). https://doi.org/10.1101/cshperspect.a022442
Talos DM, Sun H, Kosaras B, Joseph A, Folkerth RD, Poduri A, Madsen JR, Black PM et al (2012) Altered inhibition in tuberous sclerosis and type IIb cortical dysplasia. Ann Neurol 71(4):539–551. https://doi.org/10.1002/ana.22696
Crino PB, Duhaime AC, Baltuch G, White R (2001) Differential expression of glutamate and GABA-A receptor subunit mRNA in cortical dysplasia. Neurology 56(7):906–913. https://doi.org/10.1212/wnl.56.7.906
Ying Z, Bingaman W, Najm IM (2004) Increased numbers of coassembled PSD-95 to NMDA-receptor subunits NR2B and NR1 in human epileptic cortical dysplasia. Epilepsia 45(4):314–321. https://doi.org/10.1111/j.0013-9580.2004.37703.x
Ferrer I, Oliver B, Russi A, Casas R, Rivera R (1994) Parvalbumin and calbindin-D28k immunocytochemistry in human neocortical epileptic foci. J Neurol Sci 123(1–2):18–25
Calcagnotto ME, Paredes MF, Tihan T, Barbaro NM, Baraban SC (2005) Dysfunction of synaptic inhibition in epilepsy associated with focal cortical dysplasia. J Neurosci 25(42):9649–9657. https://doi.org/10.1523/jneurosci.2687-05.2005
Andre VM, Cepeda C, Vinters HV, Huynh M, Mathern GW, Levine MS (2010) Interneurons, GABAA currents, and subunit composition of the GABAA receptor in type I and type II cortical dysplasia. Epilepsia 51(Suppl 3):166–170. https://doi.org/10.1111/j.1528-1167.2010.02634.x
Barinka F, Druga R, Marusic P, Krsek P, Zamecnik J (2010) Calretinin immunoreactivity in focal cortical dysplasias and in non-malformed epileptic cortex. Epilepsy Res 88(1):76–86. https://doi.org/10.1016/j.eplepsyres.2009.09.021
Medici V, Rossini L, Deleo F, Tringali G, Tassi L, Cardinale F, Bramerio M, de Curtis M et al (2016) Different parvalbumin and GABA expression in human epileptogenic focal cortical dysplasia. Epilepsia 57(7):1109–1119. https://doi.org/10.1111/epi.13405
Nakagawa JM, Donkels C, Fauser S, Schulze-Bonhage A, Prinz M, Zentner J, Haas CA (2017) Characterization of focal cortical dysplasia with balloon cells by layer-specific markers: evidence for differential vulnerability of interneurons. Epilepsia 58(4):635–645. https://doi.org/10.1111/epi.13690
Blauwblomme T, Dossi E, Pellegrino C, Goubert E, Iglesias BG, Sainte-Rose C, Rouach N, Nabbout R et al (2019) Gamma-aminobutyric acidergic transmission underlies interictal epileptogenicity in pediatric focal cortical dysplasia. Ann Neurol 85(2):204–217. https://doi.org/10.1002/ana.25403
Wong FK, Bercsenyi K, Sreenivasan V, Portales A, Fernandez-Otero M, Marin O (2018) Pyramidal cell regulation of interneuron survival sculpts cortical networks. Nature 557(7707):668–673. https://doi.org/10.1038/s41586-018-0139-6
Guerrini R, Duchowny M, Jayakar P, Krsek P, Kahane P, Tassi L, Melani F, Polster T et al (2015) Diagnostic methods and treatment options for focal cortical dysplasia. Epilepsia 56(11):1669–1686. https://doi.org/10.1111/epi.13200
Hsieh LS, Wen JH, Claycomb K, Huang Y, Harrsch FA, Naegele JR, Hyder F, Buchanan GF et al (2016) Convulsive seizures from experimental focal cortical dysplasia occur independently of cell misplacement. Nat Commun 7:11753. https://doi.org/10.1038/ncomms11753
Meng XF, Yu JT, Song JH, Chi S, Tan L (2013) Role of the mTOR signaling pathway in epilepsy. J Neurol Sci 332(1–2):4–15. https://doi.org/10.1016/j.jns.2013.05.029
Bateup HS, Johnson CA, Denefrio CL, Saulnier JL, Kornacker K, Sabatini BL (2013) Excitatory/inhibitory synaptic imbalance leads to hippocampal hyperexcitability in mouse models of tuberous sclerosis. Neuron 78(3):510–522. https://doi.org/10.1016/j.neuron.2013.03.017
Lamparello P, Baybis M, Pollard J, Hol EM, Eisenstat DD, Aronica E, Crino PB (2007) Developmental lineage of cell types in cortical dysplasia with balloon cells. Brain J Neurol 130(Pt 9):2267–2276. https://doi.org/10.1093/brain/awm175
D'Gama AM, Woodworth MB, Hossain AA, Bizzotto S, Hatem NE, LaCoursiere CM, Najm I, Ying Z et al (2017) Somatic mutations activating the mTOR pathway in dorsal telencephalic progenitors cause a continuum of cortical dysplasias. Cell Rep 21(13):3754–3766. https://doi.org/10.1016/j.celrep.2017.11.106
Li J, Wang C, Zhang Z, Wen Y, An L, Liang Q, Xu Z, Wei S et al (2018) Transcription factors Sp8 and Sp9 coordinately regulate olfactory bulb interneuron development. Cereb Cortex (New York, NY : 1991) 28(9):3278–3294. https://doi.org/10.1093/cercor/bhx199
Baek ST, Copeland B, Yun EJ, Kwon SK, Guemez-Gamboa A, Schaffer AE, Kim S, Kang HC et al (2015) An AKT3-FOXG1-reelin network underlies defective migration in human focal malformations of cortical development. Nat Med 21(12):1445–1454. https://doi.org/10.1038/nm.3982
Markram H, Toledo-Rodriguez M, Wang Y, Gupta A, Silberberg G, Wu C (2004) Interneurons of the neocortical inhibitory system. Nat Rev Neurosci 5(10):793–807. https://doi.org/10.1038/nrn1519
Lim L, Mi D, Llorca A, Marin O (2018) Development and functional diversification of cortical interneurons. Neuron 100(2):294–313. https://doi.org/10.1016/j.neuron.2018.10.009
Bartolini G, Ciceri G, Marin O (2013) Integration of GABAergic interneurons into cortical cell assemblies: lessons from embryos and adults. Neuron 79(5):849–864. https://doi.org/10.1016/j.neuron.2013.08.014
Maffei A, Charrier C, Caiati MD, Barberis A, Mahadevan V, Woodin MA, Tyagarajan SK (2017) Emerging mechanisms underlying dynamics of GABAergic synapses. J Neurosci 37(45):10792–10799. https://doi.org/10.1523/jneurosci.1824-17.2017
Spreafico R, Tassi L, Colombo N, Bramerio M, Galli C, Garbelli R, Ferrario A, Lo Russo G et al (2000) Inhibitory circuits in human dysplastic tissue. Epilepsia 41(Suppl 6):S168–S173. https://doi.org/10.1111/j.1528-1157.2000.tb01576.x
Han P, Welsh CT, Smith MT, Schmidt RE, Carroll SL (2019) Complex patterns of GABAergic neuronal deficiency and type 2 potassium-chloride Cotransporter immaturity in human focal cortical dysplasia. J Neuropathol Exp Neurol 78(4):365–372. https://doi.org/10.1093/jnen/nlz009
Weston MC, Chen H, Swann JW (2014) Loss of mTOR repressors Tsc1 or Pten has divergent effects on excitatory and inhibitory synaptic transmission in single hippocampal neuron cultures. Front Mol Neurosci 7:1. https://doi.org/10.3389/fnmol.2014.00001
Taylor DC, Falconer MA, Bruton CJ, Corsellis JA (1971) Focal dysplasia of the cerebral cortex in epilepsy. J Neurol Neurosurg Psychiatry 34(4):369–387
Powell EM (2013) Interneuron development and epilepsy: early genetic defects cause long-term consequences in seizures and susceptibility. Epilepsy Curr 13(4):172–176. https://doi.org/10.5698/1535-7597-13.4.172
Hanai S, Saito T, Nakagawa E, Arai A, Otsuki T, Sasaki M, Goto Y, Itoh M (2010) Abnormal maturation of non-dysmorphic neurons in focal cortical dysplasia: immunohistochemical considerations. Seizure 19(5):274–279. https://doi.org/10.1016/j.seizure.2010.04.003
Zamecnik J, Krsek P, Druga R, Marusic P, Benes V, Tichy M, Komarek V (2006) Densities of parvalbumin-immunoreactive neurons in non-malformed hippocampal sclerosis-temporal neocortex and in cortical dysplasias. Brain Res Bull 68(6):474–481. https://doi.org/10.1016/j.brainresbull.2005.10.008
Garbelli R, Munari C, De Biasi S, Vitellaro-Zuccarello L, Galli C, Bramerio M, Mai R, Battaglia G et al (1999) Taylor's cortical dysplasia: a confocal and ultrastructural immunohistochemical study. Brain Pathol (Zurich, Switzerland) 9(3):445–461. https://doi.org/10.1111/j.1750-3639.1999.tb00534.x
McDonald AJ, Mascagni F (2001) Colocalization of calcium-binding proteins and GABA in neurons of the rat basolateral amygdala. Neuroscience 105(3):681–693. https://doi.org/10.1016/s0306-4522(01)00214-7
Zhao C, Eisinger B, Gammie SC (2013) Characterization of GABAergic neurons in the mouse lateral septum: a double fluorescence in situ hybridization and immunohistochemical study using tyramide signal amplification. PLoS One 8(8):e73750. https://doi.org/10.1371/journal.pone.0073750
Ma T, Wang C, Wang L, Zhou X, Tian M, Zhang Q, Zhang Y, Li J et al (2013) Subcortical origins of human and monkey neocortical interneurons. Nat Neurosci 16(11):1588–1597. https://doi.org/10.1038/nn.3536
Popescu IR, Morton LA, Franco A, Di S, Ueta Y, Tasker JG (2010) Synchronized bursts of miniature inhibitory postsynaptic currents. J Physiol 588(Pt 6):939–951. https://doi.org/10.1113/jphysiol.2009.181461
Andre VM, Cepeda C, Vinters HV, Huynh M, Mathern GW, Levine MS (2008) Pyramidal cell responses to gamma-aminobutyric acid differ in type I and type II cortical dysplasia. J Neurosci Res 86(14):3151–3162. https://doi.org/10.1002/jnr.21752
Otsu Y, Murphy TH (2003) Miniature transmitter release: accident of nature or careful design? Sci STKE 2003(211):pe54. https://doi.org/10.1126/stke.2112003pe54
Zhao JP, Yoshii A (2019) Hyperexcitability of the local cortical circuit in mouse models of tuberous sclerosis complex. Mol Brain 12(1):6. https://doi.org/10.1186/s13041-019-0427-6
Friedel P, Kahle KT, Zhang J, Hertz N, Pisella LI, Buhler E, Schaller F, Duan J et al (2015) WNK1-regulated inhibitory phosphorylation of the KCC2 cotransporter maintains the depolarizing action of GABA in immature neurons. Sci Signal 8(383):ra65. https://doi.org/10.1126/scisignal.aaa0354
Moore YE, Kelley MR, Brandon NJ, Deeb TZ, Moss SJ (2017) Seizing control of KCC2: A new therapeutic target for epilepsy. Trends Neurosci 40(9):555–571. https://doi.org/10.1016/j.tins.2017.06.008
Delarue M, Brittingham GP, Pfeffer S, Surovtsev IV, Pinglay S, Kennedy KJ, Schaffer M, Gutierrez JI et al (2018) mTORC1 controls phase separation and the biophysical properties of the cytoplasm by tuning crowding. Cell 174(2):338–349.e320. https://doi.org/10.1016/j.cell.2018.05.042
Wong M (2010) Mammalian target of rapamycin (mTOR) inhibition as a potential antiepileptogenic therapy: from tuberous sclerosis to common acquired epilepsies. Epilepsia 51(1):27–36. https://doi.org/10.1111/j.1528-1167.2009.02341.x
Acknowledgments
We are grateful to Professor Yunli Xie (Fudan University) for the generous gift of pCAG-GFP plasmid.
Funding
This work was funded by project grants from the National Natural Science Foundation of China (Code: 81771308,31771184).
Author information
Authors and Affiliations
Corresponding authors
Ethics declarations
Conflict of Interest
The authors declare that they have no conflicts of interest.
Ethics Approval
This study was approved by the Ethics Committee of Zhongshan Hospital, Fudan University.
Additional information
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Electronic supplementary material
ESM 1
(PDF 48320 kb)
Rights and permissions
About this article
Cite this article
Zhong, S., Zhao, Z., Xie, W. et al. GABAergic Interneuron and Neurotransmission Are mTOR-Dependently Disturbed in Experimental Focal Cortical Dysplasia. Mol Neurobiol 58, 156–169 (2021). https://doi.org/10.1007/s12035-020-02086-y
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12035-020-02086-y