Different effects of enhanced and reduced expression of pub gene on the formation of embryoid bodies by cultured embryonic mouse stem cell

Many Faces of TRIM Proteins on the Road from Pluripotency to Neurogenesis

Tripartite motif (TRIM) proteins participate in numerous biological processes. They are the key players in immune system and are involved in the oncogenesis. Moreover, TRIMs are the highly conserved regulators of developmental pathways in both vertebrates and invertebrates. In particular, numerous data point to the participation of TRIMs in the determination of stem cell fate, as well as in the neurogenesis. TRIMs apply various mechanisms to perform their functions. Their common feature is the ability to ubiquitinate proteins mediated by the Really Interesting New Gene (RING) domain. Different C-terminal domains of TRIMs are involved in DNA and RNA binding, protein/protein interactions, and chromatin-mediated transcriptional regulation. Mutations and alterations of TRIM expression cause significant disturbances in the stem cells' self-renewal and neurogenesis, which result in the various pathologies of the nervous system (neurodegeneration, neuroinflammation, and malignant transformation). This review discusses the diverse molecular mechanisms of participation of TRIMs in stem cell maintenance and self-renewal as well as in neural differentiation processes and neuropathology.

Expression of the human TRIM14 and its mutant form (P207L) promotes apoptosis in transgenic loaches

The tripartite-motif (TRIM)14 protein, one of the TRIM family members, was shown to participate in the antiviral and antibacterial defence. Besides, it appears to play an essential role in the processes of oncogenesis. In some types of human tumour cells, TRIM14 has been shown to inhibit apoptosis, while in others-the overexpression of TRIM14 promotes apoptosis. However, whether TRIM14 mediates apoptosis in the normal cells remains unknown. In the present study, we investigated the possible participation of the human TRIM14 gene and its mutant form (620C > T) in the induction of apoptosis in the transgenic larvae loach Misgurnus fossilis L. We observed that the expression of both forms of TRIM14 gene was accompanied by the increase of the frequency of pyknotic nuclei in fish embryos compared to control groups. Accordingly, using the TUNEL assay, the enhanced apoptosis was revealed upon expression of both forms of TRIM14 gene. The transcription of proapoptotic genes (bax, tp53, and casp9) was significantly increased in transgenic loaches expressing human wild-type TRIM14, but remained unchanged upon expression of its mutant form. In addition, the transcription of c-myc was upregulated in transgenic loaches expressing both forms. Thus, it can be assumed that during embryonic development TRIM14 has a proapoptotic effect on the cells via the activation of c-myc, tp53, and bax genes. Apparently, the mutant TRIM14 directs apoptosis via c-myc by p53-independent mechanism.

Trim14 overexpression causes the same transcriptional changes in mouse embryonic stem cells and human HEK293 cells

The trim14 (pub, KIAA0129) gene encodes the TRIM14 protein which is a member of the tripartite motif (TRIM) family. Previously, we revealed high expression levels of trim14 in HIV- or SIV-associated lymphomas and demonstrated the influence of trim14 on mesodermal differentiation of mouse embryonic stem cells (mESC). In the present work, to elucidate the role of trim14 in normal and pathological processes in the cell, we used two different types of cells transfected with trim14: mESC and human HEK293. Using subtractive hybridization and real-time PCR, we found a number of genes which expression was elevated in trim14-transfected mESC: hsp90ab1, prr13, pu.1, tnfrsf13c (baff-r), tnfrsf13b (taci), hlx1, hbp1, junb, and pdgfrb. A further analysis of the trim14-transfected mESC at the initial stage of differentiation (embryoid bodies (EB) formation) showed essential changes in the expression of these upregulated genes. The transfection of trim14 into HEK293 also induced an enhanced expression of the several genes upregulated in trim14-transfected mESC (hsp90ab1, prr13, pu.1, tnfrsf13c (baff-r), tnfrsf13b (taci), and hlx1). Summarizing, we found similar genes that participated in trim14-directed processes both in mESC and in HEK293. These results demonstrate the presence of the similar mechanism of trim14 gene action in different types of mammalian cells.