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Shen MM, Wang H, Leder P. A differential display strategy identifies Cryptic, a novel EGF-related gene expressed in the axial and lateral mesoderm during mouse gastrulation. Development 1997; 124:429-42. [PMID: 9053319 DOI: 10.1242/dev.124.2.429] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have developed a differential display screening approach to identify mesoderm-specific genes, relying upon the differentiation of embryonic stem (ES) cells in vitro. Using this strategy, we have isolated a novel murine gene that encodes a secreted molecule containing a variant epidermal growth factor-like (EGF) motif. We named this gene Cryptic, based on its predicted protein sequence similarity with Cripto, which encodes an EGF-related growth factor. Based on their strong sequence similarities, we propose that Cryptic, Cripto, and the Xenopus FRL-1 gene define a new family of growth factor-like molecules, which we name the ‘CFC’ (Cripto, Frl-1, and Cryptic) family. Analysis of Cryptic expression by in situ hybridization shows that it is expressed during gastrulation in two spatial domains that correspond to the axial and lateral mesoderm. In the first domain of expression, Cryptic expression is progressively localized to the anterior primitive streak, the head process, and the node and notochordal plate. In the second domain, Cryptic expression is initially concentrated in the lateral region of the egg cylinder, and is later found circumferentially in the intermediate and lateral plate mesoderm. Furthermore, Cryptic expression can also be detected at the early head-fold stage in the midline neuroectoderm, and consequently is an early marker for the prospective floor plate of the neural tube. Expression of Cryptic ceases at the end of gastrulation, and has not been observed in later embryonic stages or in adult tissues. Thus, Cryptic encodes a putative signaling molecule whose expression suggests potential roles in mesoderm and/or neural patterning during gastrulation.
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Catron KM, Wang H, Hu G, Shen MM, Abate-Shen C. Comparison of MSX-1 and MSX-2 suggests a molecular basis for functional redundancy. Mech Dev 1996; 55:185-99. [PMID: 8861098 DOI: 10.1016/0925-4773(96)00503-5] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This study examines the biochemical properties of two members of the murine MSX family, MSX-1 and MSX-2, which have been implicated to have partially overlapping functions during embryogenesis. Our analyses show that MSX-1 and MSX-2 share many features in common including their DNA binding and transcriptional properties. In particular, MSX-1 and MSX-2 interact with a common consensus DNA site, and exhibit similar DNA binding site preferences. However, MSX-2 has a higher apparent affinity for DNA, and the distinction between MSX-1 and MSX-2 resides in their differing sequences N-terminal to the homeodomain. With respect to their transcriptional properties, both MSX-1 and MSX-2 function as repressors and share the distinct property that they do so independently of their consensus DNA binding sites. However, MSX-1 is a more potent repressor, and the difference between these proteins also maps to their N-terminal regions. Similarly, the expression patterns of Msx-1 and Msx-2 as examined by whole mount in situ hybridization are related but not identical. Thus, Msx-1 and Msx-2 are co-expressed in the limbs, neural tube, and branchial arches; however, Msx-1 has a broader expression pattern overall and is expressed uniquely in certain embryonic regions. These features suggest that these members of the Msx family are 'equivalent but not equal' and that their proposed redundancy may be achieved via distinct biochemical mechanisms that yield a similar functional outcome.
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153
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Deng CX, Wynshaw-Boris A, Shen MM, Daugherty C, Ornitz DM, Leder P. Murine FGFR-1 is required for early postimplantation growth and axial organization. Genes Dev 1994; 8:3045-57. [PMID: 8001823 DOI: 10.1101/gad.8.24.3045] [Citation(s) in RCA: 557] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We have explored the role of fibroblast growth factor receptor 1 (FGFR-1) in early embryonic development using three experimental systems: genetically deficient mice, in vitro blastocyst culture, and FGFR-1-deficient embryonic stem cells. Using these systems, we demonstrate that FGFR-1 is required for proper embryonic cell proliferation and for the correct axial organization of early postimplantation embryos but not for mesoderm formation. FGFR-1-deficient embryos display severe growth retardation both in vitro and in vivo and die prior to or during gastrulation. Although these mutants can form nonaxial tissues, such as the allantois, amnion, and yolk sac mesoderm, they display defective patterning of the primitive streak and other axial structures, and frequently exhibit truncations or disorganization of posterior embryonic regions. Such abnormalities are unlikely to be caused by intrinsic blocks in mesodermal differentiation, as FGFR-1-deficient ES cell lines form teratomas consisting of many mesodermal cell types.
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154
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Shen MM, Skoda RC, Cardiff RD, Campos-Torres J, Leder P, Ornitz DM. Expression of LIF in transgenic mice results in altered thymic epithelium and apparent interconversion of thymic and lymph node morphologies. EMBO J 1994; 13:1375-85. [PMID: 8137821 PMCID: PMC394955 DOI: 10.1002/j.1460-2075.1994.tb06391.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Leukemia inhibitory factor (LIF) is a cytokine involved in embryonic and hematopoietic development. To investigate the effects of LIF on the lymphoid system, we generated a line of transgenic mice that expresses diffusible LIF protein specifically in T cells. These mice display two categories of phenotype that were not previously attributed to LIF overexpression. First, they display B cell hyperplasia, polyclonal hypergammaglobulinemia and mesangial proliferative glomerulonephritis, defects similar to those described for transgenic mice overexpressing the functionally related cytokine, interleukin-6. Secondly, the LIF transgenic mice display novel thymic and lymph node abnormalities. In the thymus, cortical CD4+CD8+ lymphocytes are lost, while numerous B cell follicles develop. Peripheral lymph nodes contain a vastly expanded CD4+CD8+ lymphocyte population. Furthermore, the thymic epithelium is profoundly disorganized, suggesting that disruption of stroma-lymphocyte interactions is responsible for many observed defects. Transplantation of transgenic bone marrow into wild type recipients transfers both the thymic and lymph node defects. However, transplantation of wild type marrow into transgenic recipients rescues the lymph node abnormality, but not the thymic defect, indicating the thymic epithelium is irreversibly altered. Our observations are consistent with a role for LIF in maintaining a functional thymic epithelium that will support proper T cell maturation.
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155
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Leder A, Kuo A, Shen MM, Leder P. In situ hybridization reveals co-expression of embryonic and adult alpha globin genes in the earliest murine erythrocyte progenitors. Development 1992; 116:1041-9. [PMID: 1295728 DOI: 10.1242/dev.116.4.1041] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Murine erythropoiesis begins with the formation of primitive red blood cells in the blood islands of the embryonic yolk sac on day 7.5 of gestation. By analogy to human erythropoiesis, it has been thought that there is a gradual switch from the exclusive expression of the embryonic alpha-like globin (zeta) to the mature adult form (alpha) in these early mouse cells. We have used in situ hybridization to assess expression of these two globin genes during embryonic development. In contrast to what might have been expected, we find that there is simultaneous expression of both zeta and alpha genes from the very onset of erythropoiesis in the yolk sac. At no time could we detect expression of embryonic zeta globin mRNA without concomitant expression of adult alpha globin mRNA. Indeed, adult alpha transcripts exceed those of embryonic zeta in the earliest red cell precursors. Moreover, the pattern of hybridization reveals co-expression of both genes within the same cells. Even in the fetal liver, which supersedes the yolk sac as the major site of murine fetal erythropoiesis, there is a brief co-expression of zeta and alpha genes followed by the exclusive expression of the adult alpha genes. These data indicate an important difference in hematopoietic ontogeny between mouse and that of human, where zeta expression precedes that of alpha. In addition to resolving the embryonic expression of these globin genes, our results suggest that the embryonic alpha-like globin gene zeta may be physiologically redundant, even during the earliest stages of embryonic development.
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156
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Shen MM, Leder P. Leukemia inhibitory factor is expressed by the preimplantation uterus and selectively blocks primitive ectoderm formation in vitro. Proc Natl Acad Sci U S A 1992; 89:8240-4. [PMID: 1518852 PMCID: PMC49893 DOI: 10.1073/pnas.89.17.8240] [Citation(s) in RCA: 179] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Among its many activities, leukemia inhibitory factor (LIF) can maintain embryonic stem cell monolayers in a pluripotent undifferentiated state. Presuming that this might reflect its physiologic role during embryogenesis, we have examined LIF expression in the embryonic environment by RNase protection assays and have determined its in vitro effect on differentiating embryonic stem cell embryoid bodies. Of all adult tissues analyzed, LIF transcripts appear only in the uterus, where their level fluctuates with the estrous cycle, peaking after ovulation. LIF expression continues in the uteri of pregnant and pseudopregnant females, with a relative peak when blastocysts are normally present. As for its effects on in vitro differentiation, we have found that LIF blocks embryoid body differentiation only partially, yet in a precise manner. Using molecular markers to follow the differentiation of defined cell types, we demonstrate that LIF selectively inhibits the formation of primitive ectoderm, while permitting the differentiation of primitive endoderm. These results suggest a specific role for LIF in preimplantation mouse development.
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157
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Miller DM, Shen MM, Shamu CE, Bürglin TR, Ruvkun G, Dubois ML, Ghee M, Wilson L. C. elegans unc-4 gene encodes a homeodomain protein that determines the pattern of synaptic input to specific motor neurons. Nature 1992; 355:841-5. [PMID: 1347150 DOI: 10.1038/355841a0] [Citation(s) in RCA: 127] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The creation of neural circuits depends on the formation of synapses between specific sets of neurons. Little is known, however, of the molecular mechanisms governing synaptic choice. A mutation in the unc-4 gene alters the pattern of synaptic input to one class of motor neurons in the Caenorhabditis elegans ventral nerve cord. In unc-4(e120), the presynaptic partners of VA motor neurons are replaced with interneurons appropriate to motor neurons of the VB class. This change in neural specificity is not accompanied by any detectable effects on neuronal morphology or process extension. We show that the absence of a functional unc-4 gene product accounts for the mutant phenotype. The unc-4 gene encodes a homeodomain protein and thus is likely to function as a transcription factor. The limited effect of the unc-4 null mutation on cell fate may mean that unc-4 regulates the expression of a small number of target genes and that the products of these genes are directly involved in the choice of synaptic partners.
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Hodgkin J, Chisholm AD, Shen MM. Major sex-determining genes and the control of sexual dimorphism in Caenorhabditis elegans. Genome 1989. [DOI: 10.1139/g89-116] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sex determination in Caenorhabditis elegans involves a cascade of major regulatory genes connecting the primary sex determining signal, X chromosome dosage, to key switch genes, which in turn direct development along either male or female pathways. Animals with one X chromosome (XO) are male, while animals with two X chromosomes (XX) are hermaphrodite: hermaphrodite development occurs because the action of the regulatory genes is modified in the germ line so that both sperm and oocytes are made inside a completely female soma. The regulatory genes are being examined by both genetic and molecular means. We discuss how these major genes, in particular the last switch gene in the cascade, tra-1, might regulate the many different sex-specific events that occur during the development of the hermaphrodite and of the male.Key words: nematode, Caenorhabditis elegans, sex determination, sexual differentiation, cell lineage analysis.
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159
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Shen MM, Hodgkin J. mab-3, a gene required for sex-specific yolk protein expression and a male-specific lineage in C. elegans. Cell 1988; 54:1019-31. [PMID: 3046751 DOI: 10.1016/0092-8674(88)90117-1] [Citation(s) in RCA: 170] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The gene mab-3 appears to regulate a subset of sex-specific events in C. elegans male development. Mutations in mab-3 have no apparent effect on hermaphrodites, but cause synthesis of yolk proteins and a limited lineage alteration in males. We infer that mab-3 has at least two distinct male-specific functions. First, mab-3 activity prevents yolk protein production by males, without affecting stage or tissue specificity of expression. Second, mab-3 activity is required for expression of the male V ray cell lineage. Epistasis analysis is most consistent with a model in which mab-3 is controlled by tra-1, the last switch gene known to act in the somatic sex determination pathway. We discuss how genes such as mab-3 might generate sexual dimorphism.
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Shen MM, Raleigh EA, Kleckner N. Physical analysis of Tn10- and IS10-promoted transpositions and rearrangements. Genetics 1987; 116:359-69. [PMID: 3038673 PMCID: PMC1203147 DOI: 10.1093/genetics/116.3.359] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
We have investigated by Southern blot hybridization the rate of IS10 transposition and other Tn10/IS10-promoted rearrangements in Escherichia coli and Salmonella strains bearing single chromosomal insertions of Tn10 or a related Tn10 derivative. We present evidence for three primary conclusions. First, the rate of IS10 transposition is approximately 10(-4) per cell per bacterial generation when overnight cultures are grown and plated on minimal media and is at least ten times more frequent than any other Tn10/IS10-promoted DNA alteration. Second, all of the chromosomal rearrangements observed can be accounted for by two previously characterized Tn10-promoted rearrangements: deletion/inversions and deletions. Together these rearrangements occur at about 10% the rate of IS10 transposition. Third, the data suggest that intramolecular Tn10-promoted rearrangements preferentially use nearby target sites, while the target sites for IS10 transposition events are scattered randomly around the chromosome.
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Shieh SM, Shen MM, Tsai WJ, Shiuan LR, Wang DJ. Serum lipids and lipoprotein abnormalities in patients with thrombotic stroke--with exploring the protective role of HDL subfractions. PROCEEDINGS OF THE NATIONAL SCIENCE COUNCIL, REPUBLIC OF CHINA. PART B, LIFE SCIENCES 1985; 9:298-304. [PMID: 3867905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The main purpose of this report is to demonstrate the presence of subfractions in serum HDL and to explore their role in the pathogenesis of thrombotic stroke Preparative untracentrifugation was used to isolate the differing density fractions of serum lipoproteins, and 2-27% polyacrylamide gradient gel electrophoresis was used to identify the character of the HDL subfractions. The study was performed on 59 Chinese males, in whom 31 were patients with thrombotic stroke affecting the cerebral cortex diagnosed by neurological examination and computed tomography; and the others grouped as healthy control. The age and Broca index of both groups were similar. The serum levels of total cholesterol and LDL-cholesterol were normal. However, in the thrombotic stroke group HDL-cholesterol was significantly lower and correlated inversely with both significantly higher levels of VLDL-cholesterol (r=-0.5392, p less than 0.01) and VLDL-triglyceride (r=-0.5866, p less than 0.01). The serum levels of total triglycerides and LDL-triglyceride were also significantly higher in patient with thrombotic stroke. The mean area percentage of HDL2b subfraction measured in the diameter range as determined by gradient gel electrophoresis was significantly lower and HDL2 also showed the same tendency in patients with thrombotic stroke. Our finding was consistent with the postulation that HDL2 or HDL2b in in particular, probably played a more protective role than any other HDL subfractions against thrombotic stroke, one of the major atherosclerotic complications.
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162
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Kahlon TS, Adamson GL, Shen MM, Lindgren FT. Sedimentation equilibrium of human low density lipoprotein subfractions. Lipids 1982; 17:323-30. [PMID: 7098773 DOI: 10.1007/bf02535189] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The molecular weights of low density lipoprotein (LDL) subfractions were determined precisely by meniscus depletion sedimentation equilibrium. Equilibrium speeds ranged from 9743 to 5896 rpm. The average molecular weights of various LDL subfractions of Sf values 9.49, 7.94, 6.42, 5.17, and 3.71 determined by sedimentation equilibrium were 2.97 X 10(6) ; 3.13 X 10(6); 2.89 X 10(6); 2.45 X 10(6); and 2.61 X 10(6) daltons, respectively; and their respective densities were 1.0267, 1.0306, 1.0358, 1.0422, and 1.0492 g/ml. Minimal hydrated molecular weights for this fractions determined by flotation velocity at 37,020 rpm were 2.57 X 10(6); 2.37 X 10(6); 2.09 X 10(6); 1.94 X 10(6); and 1.81 X 10(6) daltons; whereas similar molecular weights determined at 52,640 rpm were 2.53 X 10(6); 2.27 X 10(6); 1.99 X 10(6); 1.86 X 10(6); and 1.74 X 10(6) daltons for the respective LDL subfractions. Higher molecular weights of fractions 2 and 5 compared to their adjacent fractions 1 and 4 by sedimentation equilibrium are of great interest. The calculated fractional ratio f/f O from sedimentation equilibrium and flotation velocity data ranges from 1.10 to 1.31, suggesting complexity and asymmetry of LDL subfraction molecules. There is also evidence that compressibility of LDL molecules may be different than that for the salt solution under high g-force. Assuming that redistributed LDL molecules at equilibrium under low g-force are spherical, it is possible that the shape of LDL molecules undergoing flotation velocity determinations may be distorted in high g-force conditions. Such distortion may be consistent with the high f/f O values obtained and may also be a basis for structural rearrangement and/or lipoprotein degradation with prolonged preparative ultracentrifugation at high g-force and pressure.
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163
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Shen MM, Krauss RM, Lindgren FT, Forte TM. Heterogeneity of serum low density lipoproteins in normal human subjects. J Lipid Res 1981. [DOI: 10.1016/s0022-2275(20)35367-0] [Citation(s) in RCA: 283] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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164
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Shen MM, Krauss RM, Lindgren FT, Forte TM. Heterogeneity of serum low density lipoproteins in normal human subjects. J Lipid Res 1981; 22:236-44. [PMID: 7240955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Equilibrium density gradient ultracentrifugation of serum low density lipoprotein (LDL) from twelve healthy human subjects was used to separate six subfractions with mean density ranging from 1.0268 to 1.0597 g/ml. Mean corrected peak flotation rate (Sof) measured by analytic ultracentrifugation, and mean particle diameter determined by negative staining electron microscopy, both declined significantly with increasing density of the subfractions. Major differences in chemical composition of the subfractions were noted, including a significantly lower triglyceride content and higher ratio of cholesteryl ester to triglyceride in the middle fractions compared with those of highest and lowest density. Concentration of fraction 2 correlated positively with HDL (P less than 0.01) and negatively with VLDL (P less than 0.001); concentration of fraction 4 correlated negatively with HDL (P less than 0.05) and positively with VLDL (P less than 0.001) and IDL (P less than 0.01). LDL may thus include subspecies of differing structure and composition which might also have different metabolic and atherogenic roles.
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