Isoform-Specific Toxicity of Mecp2 in Postmitotic Neurons: Suppression of Neurotoxicity by FoxG1

Dastidar, Somasish Ghosh; Bardai, Farah H.; Ma, Chi; Price, Valerie; Rawat, Varun; Verma, Pragya; Narayanan, Vinodh; D’Mello, Santosh R.

doi:10.1523/jneurosci.5841-11.2012

Cited by 70 publications

(72 citation statements)

References 45 publications

(94 reference statements)

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“…The text has now been corrected: PV immunoreactivity develops postnatally: in mice, it appears around eye opening at P13-P14 in intermediate layers, from which it expands to the upper and inner cortical layers at subsequent developmental stages. (Dastidar et al, 2012) suggesting that, at least in the Central Nervous system (CNS),…”

Section: Minor Pointsmentioning

confidence: 99%

Visual impairment in FOXG1-mutated individuals and mice

et al. 2016

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The Forkead Box G1 (FOXG1) gene encodes for a DNA−binding transcription factor, essential for the development of the telencephalon in mammalian forebrain. Mutations in FOXG1 have been reported to be involved in the onset of Rett Syndrome, for which sequence alterations of MECP2 and CDKL5 are known. While visual alterations are not classical hallmarks of Rett syndrome, an increasing body of evidence shows visual impairment in patients and in MeCP2 and CDKL5 animal models. Herein we focused on the functional role of FOXG1 in the visual system of animal models (Foxg1+/Cre mice) and of a cohort of patients carrying FOXG1 mutations or deletions. Visual physiology of Foxg1+/Cre mice was assessed by visually evoked potentials, which revealed a significant reduction in response amplitude and visual acuity with respect to wild-type littermates. Morphological investigation showed abnormalities in the organization of excitatory/inhibitory circuits in the visual cortex. No alterations were observed in retinal structure. By examining a cohort of FOXG1-mutated patients by means of a panel of neuro-ophthalmological evaluations, we found that all of them exhibited visual alterations compatible with high level visual dysfunctions. In conclusion our data show that Foxg1 haploinsufficiency results in an impairment of mouse and patient visual function. Response to Reviewers: Pisa February 27th 2016Dear Editor, We would like to thank the referees for the thoughtful critiques on our manuscript and for the opportunity to revise our work. Please find enclosed a revised version of our manuscript (NSC-15-1232) entitled "Visual impairment in FOXG1-mutated patients and mice" by Boggio et al. As requested, we performed additional experiments on retina and visual cortex in order to more quantitavely prove the structure specific alterations and strengthen our conclusions. We included below a detailed response to the reviewer comments (in italics). References have been updated and added as suggested by referees. Sincerely, Tommaso PizzorussoReviewer #1:Major concerns 1.The description of the morphology of the five classes of retinal neurons would benefit from a quantitative approach amenable to statistical comparisons, similar to that performed for cortical GABAergic neurons in Fig. 4.We performed the requested quantitative analysis that is now shown in fig. 4. The analysis was focussed on cells in the ganglion cell layer because this layer is known to be affected in Foxg1 null mice. No significant change in the overall number of cells, and in ganglion cells identified using the RBPMS cell type-specific antibody, was present in Foxg1 heterozygous mice 2.There are no explicit statements regarding blinding of investigators to mouse genotypes during data acquisition and analyses, the use of Power Analysis to determine sample sizes, and predetermined criteria to exclude data sets. These are all critical issues that need to be performed and explicitly reported as recommended (Landis et al. Nature 2012).We included in the methods the fol...

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Section: Minor Pointsmentioning

confidence: 99%

Visual impairment in FOXG1-mutated individuals and mice

et al. 2016

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“…33 Although their exact interaction is yet to be defined, this may suggest a common pathway or interaction at crucial points of brain development.…”

Section: Q12 Microdeletionsmentioning

confidence: 99%

14q12 microdeletions excluding FOXG1 give rise to a congenital variant Rett syndrome-like phenotype

Ellaway

Bettella

et al. 2012

Eur J Hum Genet

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Rett syndrome is a clinically defined neurodevelopmental disorder almost exclusively affecting females. Usually sporadic, Rett syndrome is caused by mutations in the X-linked MECP2 gene in B90-95% of classic cases and 40-60% of individuals with atypical Rett syndrome. Mutations in the CDKL5 gene have been associated with the early-onset seizure variant of Rett syndrome and mutations in FOXG1 have been associated with the congenital Rett syndrome variant. We report the clinical features and array CGH findings of three atypical Rett syndrome patients who had severe intellectual impairment, early-onset developmental delay, postnatal microcephaly and hypotonia. In addition, the females had a seizure disorder, agenesis of the corpus callosum and subtle dysmorphism. All three were found to have an interstitial deletion of 14q12. The deleted region in common included the PRKD1 gene but not the FOXG1 gene. Gene expression analysis suggested a decrease in FOXG1 levels in two of the patients. Screening of 32 atypical Rett syndrome patients did not identify any pathogenic mutations in the PRKD1 gene, although a previously reported frameshift mutation affecting FOXG1 (c.256dupC, p.Gln86ProfsX35) was identified in a patient with the congenital Rett syndrome variant. There is phenotypic overlap between congenital Rett syndrome variants with FOXG1 mutations and the clinical presentation of our three patients with this 14q12 microdeletion, not encompassing the FOXG1 gene. We propose that the primary defect in these patients is misregulation of the FOXG1 gene rather than a primary abnormality of PRKD1.

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“…Gene expression studies show that different brain regions are enriched with different splice variants; MeCP2e2 is prevalent in dorsal thalamus and layer of the cortex while MeCP2-e1 is detected in the hypothalamus (51). Recent results suggest that MeCP2-e2 isoform is upregulated in Aβ-treated cortical neurons and promotes neuronal death in postmitotic neurons, a pathway normally inhibited by forkhead protein FOXG1 (64). Since MeCP2 is expressed in mature neurons and its levels increase during postnatal development, MeCP2 may play a role in modulating the activity or plasticity of mature neurons.…”

Section: Mecp2 Expression and Functionsmentioning

confidence: 99%

A review of Rett syndrome (RTT) with induced pluripotent stem cells

Vellingiri

Venkatesan

Gomathi

et al. 2016

Stem Cell Investig.

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Human induced pluripotent stem cells (hiPSCs) are pluripotent stem cells generated from somatic cells by the introduction of a combination of pluripotency-associated genes such as OCT4, SOX2, along with either KLF4 and c-MYC or NANOG and LIN28 via retroviral or lentiviral vectors. Most importantly, hiPSCs are similar to human embryonic stem cells (hESCs) functionally as they are pluripotent and can potentially differentiate into any desired cell type when provided with the appropriate cues, but do not have the ethical issues surrounding hESCs. For these reasons, hiPSCs have huge potential in translational medicine such as disease modeling, drug screening, and cellular therapy. Indeed, patient-specific hiPSCs have been generated for a multitude of diseases, including many with a neurological basis, in which disease phenotypes have been recapitulated in vitro and proof-of-principle drug screening has been performed.As the techniques for generating hiPSCs are refined and these cells become a more widely used tool for understanding brain development, the insights they produce must be understood in the context of the greater complexity of the human genome and the human brain. Disease models using iPS from Rett syndrome (RTT) patient's fibroblasts have opened up a new avenue of drug discovery for therapeutic treatment of RTT. The analysis of X chromosome inactivation (XCI) upon differentiation of RTT-hiPSCs into neurons will be critical to conclusively demonstrate the isolation of pre-XCI RTT-hiPSCs in comparison to post-XCI RTThiPSCs. The current review projects on iPSC studies in RTT as well as XCI in hiPSC were it suggests for screening new potential therapeutic targets for RTT in future for the benefit of RTT patients. In conclusion, patient-specific drug screening might be feasible and would be particularly helpful in disorders where patients frequently have to try multiple drugs before finding a regimen that works.

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Isoform-Specific Toxicity of Mecp2 in Postmitotic Neurons: Suppression of Neurotoxicity by FoxG1

Cited by 70 publications

References 45 publications

Visual impairment in FOXG1-mutated individuals and mice

Visual impairment in FOXG1-mutated individuals and mice

14q12 microdeletions excluding FOXG1 give rise to a congenital variant Rett syndrome-like phenotype

A review of Rett syndrome (RTT) with induced pluripotent stem cells

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