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The pluripotent state of embryonic stem cells (ESCs) is regulated by a sophisticated network of transcription factors. High expression of KLF17 has recently been identified as a hallmark of naive state of human ESCs (hESCs). However, the functional role of KLF17 in naive state is not clear. Here, by employing various gain and loss-of-function approaches, we demonstrate that KLF17 is essential for the maintenance of naive state and promotes the primed to naive state transition in hESCs. Mechanistically, we identify MAPK3 and ZIC2 as two direct targets repressed by KLF17. Overexpression of MAPK3 or ZIC2 partially blocks KLF17 from promoting the naive pluripotency. Furthermore, we find that human and mouse homologs of KLF17 retain conserved functions in promoting naive pluripotency of both species. Finally, we show that Klf17 may be essential for early embryo development in mouse. These findings demonstrate the important and conserved function of KLF17 in promoting naive pluripotency and reveal two essential transcriptional targets of KLF17 that underlie its function. [ABSTRACT FROM AUTHOR]

Purpose: The etiology of nasopharyngeal carcinoma (NPC) is multifactorial, complex and not fully characterized yet. MicroRNAs (miRNAs or miRs) have been found to contribute to the development and progression of NPC. Here, we aimed to investigate the putative role of miR-129-5p in NPC lymphangiogenesis and lymph node metastasis (LNM), including the involvement of its target gene ZIC2 and the Hedgehog signaling pathway. Methods: The expression of miR-129-5p and ZIC2 in primary NPC tissues was assessed using RT-qPCR and Western blot analyses, followed by LNM and lymph vessel density (LVD) correlation analyses. A direct interaction between miR-129-5p and ZIC2 was verified using a dual-luciferase reporter assay. Gain- and loss-of-function experiments were conducted to investigate the effects of miR-129-5p and ZIC2 expression on NPC cell invasion, migration and proliferation in vitro, as well as on LDV and LNM in nude mice in vivo. Additionally, RT-qPCR and Western blot analyses were performed to determine the expression levels of Hedgehog signaling pathway-related factors. Results: We found that ZIC2 was highly expressed, and miR-129-5p was lowly expressed, in primary NPC tissues. In addition, we found that miR-129-5p can directly bind to and reduce ZIC2 expression. LVD was found to be negatively correlated with miR-129-5p and to be positively correlated with ZIC2 expression. Concomitantly, we found that miR-129-5p abrogated activation of the Hedgehog signaling pathway via ZIC2 targeting, leading to suppression of NPC cell invasion, migration and proliferation in vitro as well as suppression of LNM and LVD in vivo. Conclusions: From our data we conclude that miR-129-5p, by decreasing ZIC2 expression, may inhibit NPC lymphangiogenesis and LNM through suppression of the Hedgehog signaling pathway. [ABSTRACT FROM AUTHOR]

Holoprosencephaly is a severe malformation of the brain characterized by abnormal formation and separation of the developing central nervous system. The prevalence is 1:250 during early embryogenesis, the live-born prevalence is 1:16 000. The etiology of HPE is extremely heterogeneous and can be teratogenic or genetic. We screened four known HPE genes in a Dutch cohort of 86 non-syndromic HPE index cases, including 53 family members. We detected 21 mutations (24.4%), 3 in SHH, 9 in ZIC2 and 9 in SIX3. Eight mutations involved amino-acid substitutions, 7 ins/del mutations, 1 frame-shift, 3 identical poly-alanine tract expansions and 2 gene deletions. Pathogenicity of mutations was presumed based on de novo character, predicted non-functionality of mutated proteins, segregation of mutations with affected family-members or combinations of these features. Two mutations were reported previously. SNP array confirmed detected deletions; one spanning the ZIC2/ZIC5 genes (approx. 100 kb) the other a 1.45 Mb deletion including SIX2/SIX3 genes. The mutation percentage (24%) is comparable with previous reports, but we detected significantly less mutations in SHH: 3.5 vs 10.7% (P=0.043) and significantly more in SIX3: 10.5 vs 4.3% (P=0.018). For TGIF1 and ZIC2 mutation the rate was in conformity with earlier reports. About half of the mutations were de novo, one was a germ line mosaic. The familial mutations displayed extensive heterogeneity in clinical manifestation. Of seven familial index patients only two parental carriers showed minor HPE signs, five were completely asymptomatic. Therefore, each novel mutation should be considered as a risk factor for clinically manifest HPE, with the caveat of reduced clinical penetrance. [ABSTRACT FROM AUTHOR]

The recent identification of some of the human holoprosencephaly genes is beginning to elucidate the intricate developmental programs that pattern normal and abnormal brain development. Here we present some of these advances in the context of our present understanding and conclude with some speculations regarding the direction for future investigations. We are living in a tremendously exciting time in medicine with the rapid application of molecular genetic approaches to the understanding of human disease. It is the purpose of this review to stress the underlying principals of our approach at a level that can be readily appreciated by colleagues who themselves are experts in brain anatomy but not necessarily the molecular genetics of brain development. [ABSTRACT FROM AUTHOR]