SRGAP2-AS1 Regulates RSV Replication and EMT-Associated Changes Through PTBP1 and ZEB1

Abstract

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract disease, but the contribution of long non-coding RNAs (lncRNAs) to RSV-induced epithelial–mesenchymal transition (EMT)-associated changes remains unclear. We used transcriptomic screening in RSV-exposed BEAS-2B cells to identify candidate lncRNAs and then examined SRGAP2-AS1 in cell and mouse models. Expression was measured by RT-qPCR, and loss- and gain-of-function experiments were combined with RNA immunoprecipitation, co-immunoprecipitation, Western blot analysis, and TCID₅₀ assays. SRGAP2-AS1 was increased in RSV-infected BEAS-2B cells and mouse lung tissue. Silencing SRGAP2-AS1 reduced viral replication, lowered IL-6 and IL-1β mRNA, increased IFN-β mRNA, and attenuated EMT-associated marker changes in RSV-infected BEAS-2B cells. SRGAP2-AS1 was predominantly cytoplasmic and enriched in PTBP1 immunoprecipitates. Reciprocal co-immunoprecipitation showed that PTBP1 and ZEB1 were present in the same endogenous complex, and ZEB1 abundance changed with SRGAP2-AS1 gain and loss of function. ZEB1 knockdown produced parallel changes in viral RNA, immune-related transcripts, and EMT-associated markers. Ectopic ZEB1 expression reversed the E-cadherin change caused by SRGAP2-AS1 depletion, supporting a downstream role for ZEB1 in the epithelial arm of the EMT-associated phenotype. These findings support regulatory relationships among SRGAP2-AS1, PTBP1, and ZEB1 during RSV infection. The causal order of the viral and immune-related changes, and the in vivo relevance of the EMT-associated phenotype, remain unresolved.