Expression of Xkl-1, a Xenopus gene related to mammalian c-kit, in dorsal embryonic tissue

Kao, Ken; Bernstein, Alan

doi:10.1016/0925-4773(94)00325-h

Cited by 22 publications

(15 citation statements)

References 67 publications

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“…C-kit receptor is a conservative molecule and the cDNA has been isolated in lower vertebrates, such as chicken (Sasaki et al 1993), Xenopus (Baker et al 1995, Kao & Bernstein 1995 and zebrafish (Parichy et al 1999). Addition of human recombinant SCF to newt testicular organ cultures stimulates the SPG proliferation and they progressed to the seventh generation, the penultimate stage before the primary spermatocyte stage.…”

Section: Discussionmentioning

confidence: 99%

The c-kit receptor protein in the testis of green frog Rana esculenta: seasonal changes in relationship to testosterone titres and spermatogonial proliferation

Raucci¹,

Fiore²

2007

Reproduction

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The green frog Rana esculenta is a seasonal breeder. The cyclic changes between almost arrested and highly activated spermatogenesis offer an ideal model to study basic mechanisms of spermatogenesis. In this study, we demonstrated, to our knowledge for the first time, c-kit receptor positive cells in the testis of this amphibian. The presence of c-kit receptor protein was confirmed by western blotting (Wb) analyses carried out in the testis during all the three main phases of the sexual cycle. The antibody recognized a band of about 150 kDa that was correlated with the positive staining in the germinal epithelium. The immunolabelling for c-kit receptor, evaluated by immunohistochemistry (IHC), was localized in I and II spermatogonia (SPG), in I and II spermatocytes, in both elongating spermatids and spermatozoa and in the Leydig cells. Furthermore, c-kit expression showed a seasonal pattern connected with both testicular and plasma profiles of testosterone during the reproductive cycle. The highest expression of c-kit receptor occurred during the reproductive period, when the testis exhibited the maximum concentration of testosterone. In this period, the mitotic activity of germ cell, assessed by both Wb and IHC analyses for proliferating cell nuclear antigen (PCNA), was intensive. Indeed, during the post-reproductive period, testosterone titres were the lowest and the expression of both PCNA and c-kit receptor protein in the testis, although present, is minor when compared with the reproductive phase. This evidence suggests that cell division can continue sufficiently to accumulate SPG for the next spring, when new germinal cells undergo multiplication. Finally, during the pre-reproductive period, testosterone levels begin to increase and mitotic activity of germinal epithelium is comparably enhanced. These events seem to precede the period of maximum stimulated spermatogonial proliferation, i.e. the reproductive period. These results suggest that the c-kit receptor may play a role in germ cell proliferation and provide a basis for future detailed investigation of regulatory factors of the proliferation of SPG.

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Section: Discussionmentioning

confidence: 99%

The c-kit receptor protein in the testis of green frog Rana esculenta: seasonal changes in relationship to testosterone titres and spermatogonial proliferation

Raucci¹,

Fiore²

2007

Reproduction

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“…In frog, a kit-related gene, Xkrk, is expressed in adult ovary, presumably in growing oocytes, but probably not in PGCs (Baker et al, 1995), nor has it been reported that kit-related genes are expressed in melanocytes, or blood precursors (Baker et al, 1995;Kao and Bernstein, 1995;Martin and Harland, 2001). Axkit is expressed in lateral line (not shown), as is Xkrk, and in notochord (Fig.…”

Section: Embryonic Expression Of Axkit Resembles Its Expression In Thmentioning

confidence: 99%

“…Axkit is expressed in lateral line (not shown), as is Xkrk, and in notochord (Fig. 4A,C), as is another kit-related gene of Xenopus, Xkl1 (Kao and Bernstein, 1995).…”

Section: Embryonic Expression Of Axkit Resembles Its Expression In Thmentioning

confidence: 99%

Gene expression in the axolotl germ line: Axdazl, Axvh, Axoct‐4, and Axkit

Bachvarova

Masi

Drum

et al. 2004

Developmental Dynamics

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“…We also examined expression of the 2 known Xenopus c-kit homologues, Xkrk 28 and Xkl, 27 using a probe that recognizes both genes. In addition to detecting c-kit expression in previously reported locations, including the nonneural ectoderm ( Figure 1C-D), we also detected expression in the mesoderm at late gastrula through neural stages ( Figure 1D arrow and data not shown), which is when Xsl-1 and Xsl-2b mRNAs are present in the overlying ectoderm.…”

Section: Xenopus Steel Is a Candidate Ectodermal Regulator Of Xenopusmentioning

confidence: 99%

“…26 Two c-kit receptors have been identified in Xenopus, but their functions are not known. 27,28 Xenopus kit-related-kinase1 (Xkrk1) shares approximately 60% amino acid identity with the mouse and chick c-kit receptors. The only other reported Xenopus c-kit homolog, Xenopus kit-like1 (Xkl1), and a closely related isoform, Xkl1A, share over 80% identity with Xkrk1 at the nucleotide level.…”

mentioning

confidence: 99%

Ectodermally derived steel/stem cell factor functions non–cell autonomously during primitive erythropoiesis in Xenopus

Goldman

Berg

Heinrich

et al. 2006

Blood

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Signals derived from nonhematopoietic tissues are essential for normal primitive erythropoiesis in vertebrates, but little is known about the nature of these signals. In Xenopus, unidentified factors secreted by ectodermal cells during gastrulation are required to enable the underlying ventral mesoderm to form blood. Steel is expressed in the ectoderm of early Xenopus embryos and is known to regulate definitive erythroid progenitor survival and differentiation in other organisms, making it an excellent candidate regulator of primitive erythropoiesis. In this study, we tested whether steel signaling is required for primitive red blood cell differentiation in mice and frogs. We show that Xsl is expressed in the ectoderm in Xenopus gastrulae and that c-kit homologs are expressed in the underlying mesoderm at the same stages of development. We present loss of function data in whole Xenopus embryos and explants that demonstrate a requirement for ectodermally derived steel to signal through c-kit in the mesoderm to support early steps in the differentiation of primitive erythroid but not myeloid cells. Finally, we show that primitive erythropoiesis is not disrupted in mouse embryos that lack c-kit function. Our data suggest a previously unrecognized and unique function of steel/c-kit during primitive erythropoiesis in Xenopus. IntroductionThe first phase of vertebrate blood development, termed primitive hematopoiesis, gives rise primarily to embryonic erythrocytes and some leukocytes. In Xenopus laevis, primitive hematopoiesis occurs intraembryonically in a ventral mesodermal cell population known as the ventral blood island (VBI), which is the functional equivalent of the mammalian yolk sac. 1,2 The VBI has 2 distinct early embryonic origins: the anterior portion of the VBI is derived from dorsal blastomeres, whereas the posterior VBI is derived from ventral blastomeres. [3][4][5] Primitive blood cells begin to differentiate within the VBI in an anterior-to-posterior wave at the tail bud stage of development, and subsequently begin to circulate after stage 33/34 when the heart starts to beat. In Xenopus, definitive hematopoiesis initiates in a separate mesodermal population located near the dorsal lateral plate and contributes adult hematopoietic stem cells. 3,6,7 This compartment is equivalent to the murine aorta, gonad mesonephros region, which is the first site of definitive hematopoiesis. [8][9][10][11] Embryologic experiments have shown that signals derived from nonhematopoietic tissues are essential for normal primitive erythropoiesis in vertebrates. [12][13][14] Numerous lines of evidence suggest that ectodermal cells, which come into contact with underlying ventral mesoderm during gastrulation, serve as an important source of such signals in Xenopus. For instance, when embryos are induced to exogastrulate, which prevents the prospective ectoderm from coming into apposition with the mesoderm, primitive erythrocytes fail to differentiate although other mesodermal cell types develop normally. 15 Tissue recombin...

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Expression of Xkl-1, a Xenopus gene related to mammalian c-kit, in dorsal embryonic tissue

Cited by 22 publications

References 67 publications

The c-kit receptor protein in the testis of green frog Rana esculenta: seasonal changes in relationship to testosterone titres and spermatogonial proliferation

The c-kit receptor protein in the testis of green frog Rana esculenta: seasonal changes in relationship to testosterone titres and spermatogonial proliferation

Gene expression in the axolotl germ line: Axdazl, Axvh, Axoct‐4, and Axkit

Ectodermally derived steel/stem cell factor functions non–cell autonomously during primitive erythropoiesis in Xenopus

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