The imprinted NPAP1/C15orf2 gene in the Prader–Willi syndrome region encodes a nuclear pore complex associated protein

Abstract

The Prader-Willi syndrome (PWS) region in 15q11q13 harbours a cluster of imprinted genes expressed from the paternal chromosome only. Whereas loss of function of the SNORD116 genes appears to be responsible for the major features of PWS, the role of the other genes is less clear. One of these genes is C15orf2, which has no orthologues in rodents, but appears to be under strong positive selection in primates. C15orf2 encodes a 1156 amino acid protein with six nuclear localisation sequences. By protein BLAST analysis and InterProScan signature recognition search, we found sequence similarity of C15orf2 to the nuclear pore complex (NPC) protein POM121. To determine whether C15orf2 is located at nuclear pores, we generated a stable cell line that inducibly expresses FLAG-tagged C15orf2 and performed immunocytochemical studies. We found that C15orf2 is present at the nuclear periphery, where it colocalizes with NPCs and nuclear lamins. At very high expression levels, we observed invaginations of the nuclear envelope. Extending these observations to three-dimensional structured illumination microscopy, which achieves an 8-fold improved volumetric resolution over conventional imaging, we saw that C15orf2 is located at the inner face of the nuclear envelope where it strongly associates with the NPC. In nuclear envelope isolation and fractionation experiments, we detected C15orf2 in the NPC and lamina fractions. These experiments for the first time demonstrate that C15orf2 is part of the NPC or its associated molecular networks. Based on our findings, we propose 'Nuclear pore associated protein 1' as the new name for C15orf2.

Altering TET dioxygenase levels within physiological range affects DNA methylation dynamics of HEK293 cells

“…We can rule out an effect of doxycycline used for induction of TET1 expression as other experiments have shown that doxycycline itself had no effect on the transcriptome of HEK293 cells. 35 Although the majority of expression changes were below 2-fold in the overexpression and knockdown studies, they could exemplarily be verified by qRT-PCR (Fig. S2).…”

Expression of imprinted genes in placenta is associated with infant neurobehavioral development

“…35,36 Several other genes associated with the formation or maintenance of the NPC have also been linked to neurodevelopment. These include nucleoporin 210 kDa (Nup210), which appears to be integral to neuronal differentiation, 37 and Nup133, for which a loss of function inhibited nuclear progenitor cells from terminally differentiating into neurons.…”

The small RNA content of human sperm reveals pseudogene-derived piRNAs complementary to protein-coding genes

“…This cluster overlaps the processed pseudogene of NPAP1 (also known as C15orf2). NPAP1 is a single-exon gene coding for a nuclear pore complex protein (Neumann et al 2012). The function and regulation of NPAP1 is of relevance to human disease as it lies in the imprinted critical region of the Prader-Willi syndrome (Farber et al 2000).…”