The ortholog of human ssDNA-binding protein SSBP3 influences neurodevelopment and autism-like behaviors in Drosophila melanogaster

• Published in: PLoS biology 2023-07, Vol.21 (7), p.e3002210-e3002210
• Main Authors: Salim, Safa, Hussain, Sadam, Banu, Ayesha, Gowda, Swetha B M, Ahammad, Foysal, Alwa, Amira, Pasha, Mujaheed, Mohammad, Farhan
• Format: Article
• Language: English
• Subjects: Amino acid sequence; Analysis; Anxiety; Autism; Behavior; Binding proteins; Biology and Life Sciences; Brain; Bristles; Cell number; Chromosome 1; Defects; Deoxyribonucleic acid; Disorders; DNA; DNA-binding protein; Dosage; Drosophila; Drosophila melanogaster; Flies; Fruit flies; Fusion protein; Gene dosage; Gene expression; Gene sequencing; Genes; Genetic aspects; Genomes; Genomics; Glial cells; Habituation; Habituation (learning); Identification and classification; Insects; Larvae; Medicine and Health Sciences; Microencephaly; Morphology; Mutation; Neurodevelopmental disorders; Neuronal-glial interactions; Neurons; Neuropil; Nucleotide sequence; Oxidative stress; Perturbation; Phenotypes; Physiology; Properties; Proteins; Reactive oxygen species; Research and Analysis Methods; RNA sequencing; Sensory perception; Signal transduction; Single-stranded DNA; Single-stranded DNA-binding protein; Social behavior; Social factors; Social Sciences; Synaptic density
• ISSN: 1545-7885; 1544-9173; 1545-7885
• DOI: 10.1371/journal.pbio.3002210

1p32.3 microdeletion/duplication is implicated in many neurodevelopmental disorders-like phenotypes such as developmental delay, intellectual disability, autism, macro/microcephaly, and dysmorphic features. The 1p32.3 chromosomal region harbors several genes critical for development; however, their validation and characterization remain inadequate. One such gene is the single-stranded DNA-binding protein 3 (SSBP3) and its Drosophila melanogaster ortholog is called sequence-specific single-stranded DNA-binding protein (Ssdp). Here, we investigated consequences of Ssdp manipulations on neurodevelopment, gene expression, physiological function, and autism-associated behaviors using Drosophila models. We found that SSBP3 and Ssdp are expressed in excitatory neurons in the brain. Ssdp overexpression caused morphological alterations in Drosophila wing, mechanosensory bristles, and head. Ssdp manipulations also affected the neuropil brain volume and glial cell number in larvae and adult flies. Moreover, Ssdp overexpression led to differential changes in synaptic density in specific brain regions. We observed decreased levels of armadillo in the heads of Ssdp overexpressing flies, as well as a decrease in armadillo and wingless expression in the larval wing discs, implicating the involvement of the canonical Wnt signaling pathway in Ssdp functionality. RNA sequencing revealed perturbation of oxidative stress-related pathways in heads of Ssdp overexpressing flies. Furthermore, Ssdp overexpressing brains showed enhanced reactive oxygen species (ROS), altered neuronal mitochondrial morphology, and up-regulated fission and fusion genes. Flies with elevated levels of Ssdp exhibited heightened anxiety-like behavior, altered decisiveness, defective sensory perception and habituation, abnormal social interaction, and feeding defects, which were phenocopied in the pan-neuronal Ssdp knockdown flies, suggesting that Ssdp is dosage sensitive. Partial rescue of behavioral defects was observed upon normalization of Ssdp levels. Notably, Ssdp knockdown exclusively in adult flies did not produce behavioral and functional defects. Finally, we show that optogenetic manipulation of Ssdp-expressing neurons altered autism-associated behaviors. Collectively, our findings provide evidence that Ssdp, a dosage-sensitive gene in the 1p32.3 chromosomal region, is associated with various anatomical, physiological, and behavioral defects, which may be relevant to neurodevelopmental disorders