The eukaryotic nuclear environment possess a dynamic highly organized architecture. Processes such as gene expression, DNA repair or RNA processing occur often in membrane-less compartments. These structures constitute of e.g. nucleic acids, proteins, lipid multimolecular condensates. Our laboratory recently discovered nanoscale globular (~100 nm) Nuclear Lipid Islets (NLIs) structures containing PI(4,5)P2 (PIP2), which are involved in efficient RNAPII transcription [1]. We aim to describe the possible function of PIP2-containing NLIs in integrating RNAPII transcription and pre-mRNA splicing at their surface. Methods: To decipher whether PIP2-containing NLIs surface recruit a regulatory proteins abovementioned processes, we employed a comparative quantitative mass spectrometry (MS) analysis of PIP2 nuclear fraction combined with super-resolution microscopy visualization of candidate proteins. Results: Our quantitative MS approach identified more than 300 putative NLIs proteins, which represents 35% of nuclear PIP2 – associated proteins. Moreover, 50 % of those proteins are connected to gene expression and more that 30 % to RNA processing. Super-resolution microscopy showed that candidate proteins form foci in nucleoplasm and associate with sub-population of NLIs. In contrary, proteins predicted by MS as NLIs-nonassociated showed random distribution in respect to nucleoplasmic PIP2 foci. Conclusions: It is known that RNA splicing occurs co-transcriptionally. We show that sub-population of NLIs interact with regulators of both RNAPII transcription and pre-mRNA splicing [2]. We hypothesis that the surface of NLIs facilitate spatiotemporal regulation of these processes. Funding: This study was supported by the Czech Academy of Sciences (JSPS-18-18); Grant Agency of the Czech Republic (16-03346S, 17-09103S, 15-08738S); Technology Agency of the Czech Republic (TE01020118); IMG ASCR, v. v. i.(RVO: 68378050); European Regional Development Fund (CZ.02.1.01/0.0/0.0/16_013/0001775). Microscopy Centre - IMG AS CR the Czech-BioImaging project (LM2015062 funded by MEYS CR). References: 1. Sobol, M., et al., Nuclear phosphatidylinositol 4,5-bisphosphate islets contribute to efficient RNA polymerase II-dependent transcription. J Cell Sci, 2018. 131(8). 2. Sztacho, M., et al., Nuclear phosphoinositides and phase separation: Important players in nuclear compartmentalization. Adv Biol Regul, 2018.