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Six1 controls patterning of the mouse otic vesicle 总被引:3,自引:0,他引:3
Ozaki H Nakamura K Funahashi J Ikeda K Yamada G Tokano H Okamura HO Kitamura K Muto S Kotaki H Sudo K Horai R Iwakura Y Kawakami K 《Development (Cambridge, England)》2004,131(3):551-562
Six1 is a member of the Six family homeobox genes, which function as components of the Pax-Six-Eya-Dach gene network to control organ development. Six1 is expressed in otic vesicles, nasal epithelia, branchial arches/pouches, nephrogenic cords, somites and a limited set of ganglia. In this study, we established Six1-deficient mice and found that development of the inner ear, nose, thymus, kidney and skeletal muscle was severely affected. Six1-deficient embryos were devoid of inner ear structures, including cochlea and vestibule, while their endolymphatic sac was enlarged. The inner ear anomaly began at around E10.5 and Six1 was expressed in the ventral region of the otic vesicle in the wild-type embryos at this stage. In the otic vesicle of Six1-deficient embryos, expressions of Otx1, Otx2, Lfng and Fgf3, which were expressed ventrally in the wild-type otic vesicles, were abolished, while the expression domains of Dlx5, Hmx3, Dach1 and Dach2, which were expressed dorsally in the wild-type otic vesicles, expanded ventrally. Our results indicate that Six1 functions as a key regulator of otic vesicle patterning at early embryogenesis and controls the expression domains of downstream otic genes responsible for respective inner ear structures. In addition, cell proliferation was reduced and apoptotic cell death was enhanced in the ventral region of the otic vesicle, suggesting the involvement of Six1 in cell proliferation and survival. In spite of the similarity of otic phenotypes of Six1- and Shh-deficient mice, expressions of Six1 and Shh were mutually independent. 相似文献
2.
Shirui Chen Wei Liu Masahiro Naganuma Yukihide Tomari Hiro-oki Iwakawa 《Nucleic acids research》2022,50(8):4669
Monocot DICER-LIKE3 (DCL3) and DCL5 produce distinct 24-nt small interfering RNAs (siRNAs), heterochromatic siRNAs (hc-siRNAs) and phased secondary siRNAs (phasiRNAs), respectively. The former small RNAs are linked to silencing of transposable elements and heterochromatic repeats, and the latter to reproductive processes. It is assumed that these DCLs evolved from an ancient ‘eudicot-type’ DCL3 ancestor, which may have produced both types of siRNAs. However, how functional differentiation was achieved after gene duplication remains elusive. Here, we find that monocot DCL3 and DCL5 exhibit biochemically distinct preferences for 5′ phosphates and 3′ overhangs, consistent with the structural properties of their in vivo double-stranded RNA substrates. Importantly, these distinct substrate specificities are determined by the PAZ domains of DCL3 and DCL5, which have accumulated mutations during the course of evolution. These data explain the mechanism by which these DCLs cleave their cognate substrates from a fixed end, ensuring the production of functional siRNAs. Our study also indicates how plants have diversified and optimized RNA silencing mechanisms during evolution. 相似文献
3.
Hiro-oki Okamura Naonori Sugai Takahiro Kanno Tsuyoshi Shimizu Iwao Ohtani 《Histochemistry and cell biology》1996,106(2):257-260
Tissue specimens from guinea pigs were examined using an enzyme-histochemical reaction to explore the presence of carbonic
anhydrase (CA) activity in the trachea. CA activity was detected in a group of morphologically distinct epithelial cells,
in goblet cells, and in glands of the tracheal mucosa. The epithelial cells showing CA activity were distributed singly and
sparsely throughout the entire trachea. These cells showed a wide morphological variability and were clearly different from
those forming the pseudostratified ciliated epithelium. Their number was higher in sections closer to the tracheal bifurcation
than in those near the larynx. Although the nature of these cells is unknown, based on their morphological and histochemical
characteristics and their distribution, they may represent a specialized chemoreceptor. To our knowledge, this is the first
report of CA localized in tracheal epithelial cells.
Accepted: 6 March 1996 相似文献
4.
Enzyme-histochemical localization of carbonic anhydrase in the inner ear of the guinea pig and several improvements of the technique 总被引:4,自引:0,他引:4
Hiro-oki Okamura Naonori Sugai Kazunori Suzuki Iwao Ohtani 《Histochemistry and cell biology》1996,106(4):425-430
We have made several improvements in the method of fixation of the inner ear and the enzyme-histochemical technique for carbonic
anhydrase (CA) detection. The results confirmed that CA is localized in the hair cells of the organ of Corti, Deiters' cells
or nerve endings, inner pillar cells, Boettcher's cells, stria vascularis, spiral ligament, spiral limbus, and spiral ganglion
cells. These results generally agree with previous histochemical observations but showed some differences. Our method preserved
tissue morphology and showed more detailed localization of CA activity in the inner ear. In particular, the marginal zone
of stria vascularis and the epithelial cells of spiral prominence, facing the endolymph, showed no CA activity, while the
suprastrial region of the spiral ligament and the supralimbal region of the spiral limbus, juxtaposed to the perilymph, showed
CA activity. In outer hair cells, the cuticular plate, which faces the endolymph showed CA activity, but the lateral membrane,
which faces the perilymph showed no CA activity. In contrast, the inner hair cell cytoplasm showed diffuse CA activity. These
results will be useful in considering ion exchange between endolymph and its adjacent cells, and between perilymph and its
adjacent structures. 相似文献
5.
Tsunoda Rikiya Bosseloir Alain Onozaki Kikuo Heinen Ernst Miyake Katsuya Okamura Hiro-oki Suzuki Kazunori Fujita Teizou Simar Léon J. Sugai Naonori 《Cell and tissue research》1997,288(2):381-389
Cell and Tissue Research - Human follicular dendritic cell (FDC)-like cells (FLC) have been utilized for the in vitro analysis of germinal center reactions. However, there is no consensus whether... 相似文献
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