Characterization of nucleolin K88 acetylation defines a new pool of nucleolin colocalizing with pre-mRNA splicing factors

► Nucleolin is acetylated in vivo. ► Antibody specific for nucleolin acetylation was developed. ► Acetylated nucleolin is present in nucleoplasmic speckles. ► Acetylated nucleolin co-localizes with splicing factor SC35. Nucleolin is a multifunctional protein that carries several post-translational modifications. We characterized nucleolin acetylation and developed antibodies specific to nucleolin K88 acetylation. Using this antibody we show that nucleolin is acetylated in vivo and is not localized in the nucleoli, but instead is distributed throughout the nucleoplasm. Immunofluorescence studies indicate that acetylated nucleolin is co-localized with the splicing factor SC35 and partially with Y12. Acetylated nucleolin is expressed in all tested proliferating cell types. Our findings show that acetylation defines a new pool of nucleolin which support a role for nucleolin in the regulation of mRNA maturation and transcription by RNA polymerase II. SC35physically interacts with Nucleolin by anti bait coimmunoprecipitation (View interaction) Nucleolin and SC35colocalize by fluorescence microscopy (View interaction)