Rajkovic A, et al reported that Obox represents a family of homeobox genes preferentially expressed in germ
cells.
The authors used in silico (electronic database) subtraction to identify ESTs that are
preferentially expressed in the adult mouse germ cells. During the analysis, they
identified Obox1 and Obox2 transcripts as preferentially expressed in the mouse
unfertilized egg libraries. Obox1 and Obox2 transcripts encode homeodomain
proteins of 204 amino acids that share 97% identity with each other. Further
characterization of mouse BACs encoding Obox1 and Obox2, as well as available
BAC and EST sequences in GenBank, identified four closely related genes: Obox3,
Obox4, Obox5, and Obox6. Northern blot analyses and RT-PCR from 10 different
adult mouse tissues showed that the six Obox family transcripts are preferentially
expressed in the gonads. In situ hybridization detected Obox1 and Obox6 transcripts
exclusively in oocytes as early as one-layer follicles and throughout folliculogenesis.
Obox1, Obox2, Obox3, Obox4, Obox5, and Obox6 map to proximal chromosome 7 in
the mouse. The Obox1 and Obox2 genomic structures revealed the presence of six
exons each. The Obox genes represent a new family of tissue-specific homeobox
genes preferentially expressed in gonads.
General function
DNA binding
Comment
Cellular localization
Nuclear
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Ovarian function
Oogenesis, Early embryo development
Comment
Oocyte-Specific Homeobox 1, Obox1, Facilitates Reprogramming by Promoting Mesenchymal-to-Epithelial Transition and Mitigating Cell Hyperproliferation. Wu L et al. (2017) Mammalian oocytes possess fascinating unknown factors, which can reprogram terminally differentiated germ cells or somatic cells into totipotent embryos. Here, we demonstrate that oocyte-specific homeobox 1 (Obox1), an oocyte-specific factor, can markedly enhance the generation of induced pluripotent stem cells (iPSCs) from mouse fibroblasts in a proliferation-independent manner and can replace Sox2 to achieve pluripotency. Overexpression of Obox1 can greatly promote mesenchymal-to-epithelial transition (MET) at early stage of OSKM-induced reprogramming, and meanwhile, the hyperproliferation of THY1-positive cells can be significantly mitigated. Subsequently, the proportion of THY1-negative cells and Oct4-GFP-positive cells increased dramatically. Further analysis of gene expression and targets of Obox1 during reprogramming indicates that the expression of Obox1 can promote epithelial gene expression and modulate cell-cycle-related gene expression. Taken together, we conclude that the oocyte-specific factor Obox1 serves as a strong activator for somatic cell reprogramming through promoting the MET and mitigating cell hyperproliferation.//////////////////