RNA-seq for iPSC-derived macrophages with/without Lipopolysaccharide (LPS) stimulation.

Wiskott-Aldrich syndrome (WAS) is an immunodeficiency disorder caused by the dysfunction of the Wiskott-Aldrich syndrome protein (WASP). Although the effect of WASP on actin -polymerization is well studied, less is known about its role in other intracellular systems. Here we show that WASP interacts with the nucleolus in macrophages. Using induced pluripotent stem cells and the CRISPR-Cas system, we show that knocking out WASP results in reduced nucleolar size, loss of roundness, decreased sub-nucleolar structure percentage, and impaired ribosomal RNA transcription. Furthermore, we identified interactions between WASP and two nucleolar proteins, including nucleophosmin 1 (NPM1) and fibrillarin (FBL). Previous research has demonstrated that a loss of NPM1 results in heightened cytokine expression following lipopolysaccharide (LPS) stimulation. We found that WASP-deficient cells presented less NPM1 and more cytokine expression in response to LPS stimulation, providing new insights on the role of the nucleolus in immune functions. Together, our study provides new information on WASP in nucleolar function and its control of inflammatory cytokine expression in response to inflammatory stimuli.