Anti-NFX1 (aa 981-1080) polyclonal antibody

The deubiquitinase USP9X is involved in multiple diseases including neurodegeneration, epilepsy, and various types of tumors by targeting different substrates. In the present study, we aimed to explore the potential substrates of USP9X and performed SILAC-based quantitative proteomics to compare these substrates in USP9X-knockdown and wild-type HeLa cells. We consequently carried out Flag-NFX1-123 tag affinity-based mass spectrometry and confirmed that the X-box binding nuclear factor NFX1-123 interacted with USP9X. Moreover, immunoprecipitation assays verified a direct interaction between USP9X and NFX1-123. Further experiments confirmed that NFX1-123 could be modified by ubiquitination and that USP9X stabilized NFX1-123 via efficient deubiquitination of NFX1-123. Knockdown of USP9X resulted in decreased NFX1-123 protein levels compared with their unchanged corresponding mRNA levels in different cell lines. In summary, we found that NFX1-123 was a bona fide substrate of the deubiquitinase USP9X and that it could be degraded by the ubiquitin-proteasome system. The present study provided new insight into understanding the biological function of USP9X by targeting its substrate NFX1-123.

Background: A recent study identified NFXL1 as a candidate gene for specific language impairment. The protein encoded by this gene is predicted to be a transcription factor based on domain similarities with NFX1, a repressor of HLA class II genes, which have themselves been implicated in specific language impairment. However, there is very little literature on the function of NFXL1. Methods: This report describes a study of NFXL1 expression in several human tissues and an investigation of differential expression in several specific brain regions through quantitative PCR as well as a study of the protein's sub-cellular localization in HEK cells and SH-SY5Y cells through immunofluorescence. Results: The NFXL1 transcript was found in all investigated tissues. In the brain, a high level of NFXL1 expression was found in the cerebellum. An analysis of the sub-cellular localization of the protein showed a cytoplasmic pattern in the investigated cells. Conclusions: The NFXL1 transcript was present in samples from different tissues; in the brain, a high expression level was found in a region implicated in some language-related pathologies. NFXL1 did not show nuclear localization, suggesting that, if it regulates transcription, certain conditions may be required for it to translocate to the nucleus.