Development Growth & Differentiation最新文献

Mammalian sex is determined by the presence or absence of a Y chromosome. The sex-specific features of each cell and tissue in the body then develop in response to the sex hormones secreted by the differentiated reproductive tissues. Both the X and Y chromosomes encode histone demethylases. However, the involvement of these histone demethylases in the development of sex differences in each cell is still unknown. One X-linked demethylase, UTX, is also predicted to have both demethylase-dependent and -independent functions. In this study, we generated UTX mutant mice in which the histone demethylase activity of UTX was decreased to disrupt only the demethylase-dependent but not the demethylase-independent function of UTX. Although UTX mutant mice are viable, fertile, and never displayed sex reversal, the expression levels of sex differentiation genes were affected. Transcriptomic analyses revealed that there was a female expression pattern bias in UTX mutant males. Moreover, the steroid biosynthesis pathway was highly affected by the UTX mutation in males, with a significant decrease in the expression of the majority of steroidogenic genes. These results suggest that the demethylation activity of UTX could contribute to the development of sex differences by the regulation of steroid biosynthesis. Further analyses using the UTX mutant mice generated in this study will provide useful information to understand how sex differences develop.

Living organisms exhibit varying regenerative abilities depending on the species. Among them, urodele amphibians have been widely used in regeneration biology due to their remarkable regenerative capacity. Iberian ribbed newts, in particular, have been established as a prominent model for regeneration research, offering advantages such as a large number of eggs spawned, a short period of sexual maturation, and the development of genetic manipulation techniques. Cell tracing is an essential method for deciphering cellular processes during organ regeneration. The multicolor reporter Brainbow, which stochastically manifests multiple fluorescent proteins based on the Cre/lox recombination system, has been utilized for clonal analysis in regenerative animal models. In this study, we aimed to utilize this valuable multicolor reporter in Iberian ribbed newts, which are gaining increasing importance as a regenerative animal model. We generated transgenic Iberian ribbed newts carrying the Brainbow3.0 reporter cassette under the control of the CAG (cytomegalovirus early enhancer/chicken beta-actin promoter/rabbit beta-globin splice acceptor) promoter. Cre recombinase induction via electroporation led to recombinant reporter expression in the brain, spinal cord, and muscle. Recombinant reporter-expressing cells could be traced in regenerating tail muscle, midbrain, and spinal cord. Additionally, we applied laser ablation to reporter-positive epithelial cells of Brainbow3.0 newts, enabling clonal analyses at the cellular level. We expect that this long-lasting multicolor reporter will prove versatile for a broad range of research fields.

Primary microcephaly (MCPH) is a rare genetic neurodevelopmental disorder caused by homologous recessive mutations of the MCPH genes. It manifests as a significant reduction in brain volume and intellectual disability at birth. More than 28 genes with several pathogeneses have been identified so far. These genes have a strong effect on DNA damage repair and apoptosis, neuronal proliferation, neuronal differentiation, and neuronal migration. These pathogenesis pathways result in aberrant cell division and cell maturation, as well as an imbalance of the type of neural cells, and eventually a reduction of brain volume. Hence, researching in a multidisciplinary approach promotes research into the different etiologies of MCPH genes and offers a positive outcome for patients. However, investigating the etiology pathways has been given less focus, and limited studies and model systems have been carried out for this complex disease. Research using simple model organisms to study these pathogenic genes is beneficial. Recently, Drosophila melanogaster has been used as a powerful and promising model organism for efficient in vivo experiments and for deciphering complex multicellular activities to unravel the function of the MCPH genes. Interestingly, about 80% of the genes that cause genetic diseases in humans have functional counterparts in D. melanogaster . Additionally, genetic similarity, simple genetics, rapid reproduction, high-throughput screening, and ease of generating transgenics make it unique. These features have prompted researchers to widely use it in research, contributing significantly to our understanding of human diseases such as cancer, Alzheimer's disease, Parkinson's disease, MCPH, and muscular dystrophy. In this review, I focus on the various pathways of MCPH genes pathogenesis and the advantage of leveraging the D. melanogaster model to dissect the etiology of MCPH genes. [Correction added on 9 August 2025, after first online publication: In the Abstract section, last sentence, pronoun ‘we’ has been changed to ‘I’.]

The in situ hybridization chain reaction (HCR) method involves designing multiple target sequences and a pair of split probes for each target. One split probe contains the complementary sequence for half of the target along with part of the initiation sequence. The other split probe contains the complementary sequence for the remaining half of the target sequence and the rest of the initiation sequence. The complete initiation sequence composed of both probes is capable of initiating a chain reaction of hairpin DNAs. This theoretical mechanism minimizes the background signal caused by a single probe; however, very low background signals have been observed in experiments. While these weak signals are not a significant problem in many cases, they can interfere with experiments if the expression of the target gene is very low, making the background signal noticeable. Reducing such background signals would benefit many scientists working with diverse species and sample types. To address this issue, we hypothesized that a single probe could bind and open the hairpin DNA through partial complementary sequences, acting as a bridge between hairpin DNA and samples through nonspecific binding. Our findings show that the addition of random oligonucleotides during the pre-hybridization and hybridization steps reduced background signals by approximately 3–90 times. This simple and easy modification of the in situ HCR technique improves the signal-to-noise ratio and facilitates the detection of mRNAs with very low expression levels.

Neanderthals, an extinct hominid, lived in Eurasia until about 40,000 years ago. According to fossils, Neanderthals had distinctive anatomical features compared to modern humans, including a long front-to-back cranium, low frontal bones, and strong skeletal formation. Furthermore, Neanderthals had large brains similar to those of modern humans, but their brain morphology was different from ours, suggesting that they had different cognitive abilities than modern humans. Recent archaic human genome analysis has unveiled genetic changes underlying Neanderthals' or modern human–specific anatomical and physiological traits. In this review, we focus on the role of GLI3, a key molecule that mediates Hedgehog signaling during vertebrate organogenesis. We discuss possible contributions of GLI3-mediated hedgehog signaling to human anatomical diversifications, including neocortical structures, which provide insights into the genetic and developmental bases for modern human evolution.

Syncytiotrophoblasts (STs) are multinucleated cells formed by the fusion of trophoblasts and play critical roles in placental development and function. Retrovirus-derived fusogenic proteins, known as syncytins, regulate trophoblast fusion by interacting with specific receptors. In humans, two syncytins, Syncytin-1 (Syn1) and Syncytin-2 (Syn2), have been identified. Although both are considered to be involved in ST formation, the expression patterns of Syn1, Syn2, and their receptors differ significantly, suggesting that Syn1 and Syn2 may have distinct roles. To investigate the functional differences of syncytins in human trophoblasts, we generated Syn1 and Syn2 knockout (KO) human trophoblast stem cells (hTSCs). ST differentiation assays revealed that Syn2 plays a predominant role in trophoblast-trophoblast fusion. We also examined the fusion between hTSCs and endometrial stromal cells (EMSCs), as trophoblasts and EMSCs interact directly during implantation, and genes encoding Syn1 and Syn2 receptors are expressed in EMSCs. This analysis revealed that hTSCs do fuse with EMSCs, and in contrast to trophoblast-trophoblast fusion, Syn1 plays a predominant role in trophoblast-EMSC fusion. Given that fusion-capable Syn1 is found only in primates whose embryos invade deep into the uterus, we hypothesize that Syn1 may be more involved in implantation rather than in trophoblast-trophoblast fusion.