CYFIP1 overexpression amplifies IL-6/STAT3 and IFN-γ/STAT1 signaling: potential implications for neuroinflammation and autism spectrum disorder.

BACKGROUND AND

OBJECTIVES

Autism spectrum disorder (ASD) encompasses a group of neurodevelopmental disorders influenced by genetic and environmental factors, although the molecular mechanisms underlying their interactions remain unclear. We previously reported dysregulated cytokine signalling in chromosome 15q-duplication syndrome (Dup(15q)), a common syndromic form of ASD. Dup(15q) induced pluripotent stem cell (iPSC)-derived neurons exhibit an amplified Signal Transducer and Activator of Transcription-3 (STAT3) response to Interleukin-6 (IL-6), a cytokine often upregulated in ASD. To identify candidate genes within the 15q region that may modify cytokine signalling, we investigated Cytoplasmic FMRP-Interacting Protein 1 (CYFIP1), as CYFIP1 dysregulation has been linked to altered expression of genes involved in immunoregulatory pathways.

METHODS

CYFIP1 was overexpressed using a plasmid vector in human HEK-293 and SH-SY5Y neuroblastoma cells. Following stimulation with IL-6 or Interferon (IFN)-γ, a variety of biochemical assays (qRT-PCR, Western blotting and dual-luciferase reporter assays) and neurite tracing experiments were performed to assess the effects of increased CYFIP1 expression on IL-6/STAT3 and IFN-γ/STAT1 signaling responses.

RESULTS

CYFIP1-overexpression HEK-293 cells display reduced STAT3 and STAT1 expression, but enhanced IL-6-induced/IFN-γ-induced STAT3/STAT1 transcriptional activity. Furthermore, CYFIP1-overexpression in SH-SY5Y cells was associated with reduced basal neurite outgrowth and altered IL-6-associated neurite outgrowth.

CONCLUSIONS

These findings suggest that CYFIP1-overexpression modifies cytokine-responsive transcriptional pathways in vitro and provides novel insight into how CYFIP1 dysregulation may contribute to dysregulated cytokine signaling in ASD, advancing our understanding of the molecular mechanisms underlying neuroinflammatory processes in this disorder.