Genetic interaction screen for severe neurodevelopmental disorders reveals a functional link between Ube3a and Mef2 in Drosophila melanogaster

Abstract

neurodevelopmental disorders (nDDs) are clinically and genetically extremely heterogeneous with shared phenotypes often associated with genes from the same networks. Mutations in TCF4, MEF2C, UBE3A, ZEB2 or ATRX cause phenotypically overlapping, syndromic forms of NDDs with severe intellectual disability, epilepsy and microcephaly. To characterize potential functional links between these genes/proteins, we screened for genetic interactions in Drosophila melanogaster. We induced ubiquitous or tissue specific knockdown or overexpression of each single orthologous gene (Da, Mef2, Ube3a, Zfh1, XNP) and in pairwise combinations. Subsequently, we assessed parameters such as lethality, wing and eye morphology, neuromuscular junction morphology, bang sensitivity and climbing behaviour in comparison between single and pairwise dosage manipulations. We found most stringent evidence for genetic interaction between Ube3a and Mef2 as simultaneous dosage manipulation in different tissues including glia, wing and eye resulted in multiple phenotype modifications. We subsequently found evidence for physical interaction between UBE3A and MEF2C also in human cells. Systematic pairwise assessment of the Drosophila orthologues of five genes implicated in clinically overlapping, severe NDDs and subsequent confirmation in a human cell line revealed interactions between UBE3A/Ube3a and MEF2C/Mef2, thus contributing to the characterization of the underlying molecular commonalities.

Signalling pathways in autism spectrum disorder: mechanisms and therapeutic implications

“… 124 Neuronal activity can promote the translation of UBE3A through the MEF2 complex. 125 TBR1 is a neuron-specific transcription factor required for activity-dependent Grin2b expression, loss of a copy of which alters the expression of Ntng1 , Cntn2 and Cdh8. 109 , 110 …”

Involvement of myocyte enhancer factor 2c in the pathogenesis of autism spectrum disorder

“…Recently, employing a fly ( Drosophila melanogaster ) as a screening model for gene interactions and by consequent co-immunoprecipitation in human cell lines, Straub et al. reported a specific functional correlation between MEF2C and UBE3A that could eventually lead to the phenotypic overlap between MEF2C -related ID and Angelman syndrome [ 185 ]. Nevertheless, there is still a need for more comprehensive scientific support of UBE3A influencing MEF2C gene in an ubiquitous manner.…”

“…Some of the traits of Angelman syndrome can indeed be found on the autism spectrum, for example poor communication skills, absence of speech, attention deficits, hyperactivity, insomnia, and a deficiency in motor growth and development [183,184]. Recently, employing a fly (Drosophila melanogaster) as a screening model for gene interactions and by consequent co-immunoprecipitation in human cell lines, Straub et al reported a specific functional correlation between MEF2C and UBE3A that could eventually lead to the phenotypic overlap between MEF2C-related ID and Angelman syndrome [185]. Nevertheless, there is still a need for more comprehensive scientific support of UBE3A influencing MEF2C gene in an ubiquitous manner.…”

Investigating Developmental and Epileptic Encephalopathy Using Drosophila melanogaster

“…Another group investigated the gene regulatory network in which Ube3a is involved [ 195 ]. Mutations in TCF4, MEF2C, UBE3A, ZEB2 or ATRX cause phenotypically overlapping, syndromic forms of neurodevelopmental disorders with severe intellectual disability, epilepsy and microcephaly.…”

“…Mutations in TCF4, MEF2C, UBE3A, ZEB2 or ATRX cause phenotypically overlapping, syndromic forms of neurodevelopmental disorders with severe intellectual disability, epilepsy and microcephaly. Global or tissue specific knockdown or overexpression of each single orthologous Drosophila genes, such as Da , Mef2 , Ube3a , Zfh1 and XNP and their pairwise combinations were carried out to examine phenotypes such as lethality, wing and eye morphology, NMJ morphology, bang sensitivity and climbing behavior and then compared between single and pairwise dosage manipulations [ 195 ]. By these analyses, genetic interaction between Ube3a and Mef2 via simultaneous dosage manipulation in tissues, such as glia, wing and eye, resulted in multiple phenotype alterations, although seizure susceptibility evaluated by the bang-sensitivity assay revealed no consistent phenotype [ 195 ].…”