Generation of induced pluripotent stem cell lines from two unrelated patients affected by intellectual disability carrying homozygous variants in SGIP1.

Intellectual disability (ID) is a diverse neurodevelopmental condition and almost half of the cases have a genetic etiology. SGIP1 acts as an endocytic protein that influences the signaling of receptors in neuronal systems related to energy homeostasis through its interaction with endophilins. This study focuses on the generation and characterization of induced pluripotent stem cells (iPSC) from two unrelated patients due to a frameshift variant (c.764dupA, NM_032291.4) and a splice donor site variant (c.74 + 1G > A, NM_032291.4) in the SGIP1 gene.

Hippocampal Trauma Memory Processing Conveying Susceptibility to Traumatic Stress.

While the majority of the population is ever exposed to a traumatic event during their lifetime, only a fraction develops posttraumatic stress disorder (PTSD). Disrupted trauma memory processing has been proposed as a core factor underlying PTSD symptomatology. We used transgenic Targeted-Recombination-in-Active-Populations (TRAP) mice to investigate potential alterations in trauma-related hippocampal memory engrams associated with the development of PTSD-like symptomatology. Mice were exposed to a stress-enhanced fear learning paradigm, in which prior exposure to a stressor affects the learning of a subsequent fearful event (contextual fear conditioning using foot shocks), during which neuronal activity was labeled. One week later, mice were behaviorally phenotyped to identify mice resilient and susceptible to developing PTSD-like symptomatology. Three weeks post-learning, mice were re-exposed to the conditioning context to induce remote fear memory recall, and associated hippocampal neuronal activity was assessed. While no differences in the size of the hippocampal neuronal ensemble activated during fear learning were observed between groups, susceptible mice displayed a smaller ensemble activated upon remote fear memory recall in the ventral CA1, higher regional hippocampal parvalbuminneuronal density and a relatively lower activity of parvalbumininterneurons upon recall. Investigation of potential epigenetic regulators of the engram revealed rather generic (rather than engram-specific) differences between groups, with susceptible mice displaying lower hippocampal histone deacetylase 2 expression, and higher methylation and hydroxymethylation levels. These finding implicate variation in epigenetic regulation within the hippocampus, as well as reduced regional hippocampal activity during remote fear memory recall in interindividual differences in susceptibility to traumatic stress.