pRb is necessary for inhibition of N-myc expression by TGF-beta 1 in embryonic lung organ cultures

Development ◽  
1995 ◽  
Vol 121 (9) ◽  
pp. 3057-3066 ◽  
Author(s):  
R. Serra ◽  
H.L. Moses

The beta type transforming growth factors (TGF-beta) are potent inhibitors of epithelial cell proliferation, and data suggest that growth inhibition by TGF-beta 1 is mediated through suppression of Myc family genes in certain cell types. Indirect evidence has indicated that the product of the retinoblastoma gene (pRb) may also be involved in this pathway. Previously, we have shown that TGF-beta 1 inhibits branching morphogenesis and N-myc expression in mouse embryonic lung cultures. The purpose of this study was to determine the role of pRb in the inhibition of branching morphogenesis and N-myc expression by TGF-beta 1. Treatment with TGF-beta 1 was shown to inhibit development of lungs from homozygous Rb null (Rb−/−) and heterozygous null (Rb+/−) mouse embryos to the same extent as lungs from wild-type (Rb+/+) embryos. However, TGF-beta 1 treatment did not suppress N-myc expression in Rb−/− as it did in Rb+/+ embryonic lung explants as determined by in situ hybridization and quantitative RT-PCR. The effect of TGF-beta 1 treatment on N-myc expression in lungs from Rb+/− embryos was intermediate between that seen in Rb+/+ and Rb−/− embryos. Embryonic lungs derived from transgenic mice expressing the SV40 large T-antigen in lung epithelium under the control of the surfactant protein C promoter also showed inhibition of development in response to TGF-beta 1 treatment. The data demonstrate that pRb is necessary for TGF-beta 1 suppression of N-myc expression but not for TGF-beta 1 inhibition of branching morphogenesis; therefore, suppression of N-myc is not necessary for inhibition of branching morphogenesis by TGF-beta 1.


Development ◽  
1994 ◽  
Vol 120 (8) ◽  
pp. 2153-2161 ◽  
Author(s):  
R. Serra ◽  
R.W. Pelton ◽  
H.L. Moses

Lung buds isolated from 11.5 days post coitum mouse embryos survive and undergo branching morphogenesis in culture. This organ culture system was used to examine the role of TGF beta 1 and N-myc expression in lung branching morphogenesis. By 24 hours, TGF beta 1 reversibly inhibited branching morphogenesis in a concentration-dependent manner. N-myc is known to be expressed during embryonic development in epithelial cells involved in branching morphogenesis and homozygous null N-myc mice have defects in lung development. In the present study, TGF beta 1 was shown to inhibit the steady-state level of N-myc RNA 3- to 4-fold at 14 and 48 hours of treatment as measured by northern blot and RNase protection analysis. Suppression of N-myc expression in epithelium was confirmed by in situ hybridization. Since inhibition of N-myc occurred prior to the observed changes in morphology and previous genetic studies have demonstrated and important role for N-myc in lung development, a model is proposed in which TGF beta 1 inhibits tracheobronchial development by inhibiting expression of N-myc.



1994 ◽  
Vol 42 (6) ◽  
pp. 733-744 ◽  
Author(s):  
R A Dodds ◽  
K Merry ◽  
A Littlewood ◽  
M Gowen

Using in situ hybridization, we investigated the expression of mRNA for interleukin-1 beta (IL1 beta), interleukin-6 (IL6), and transforming growth factor-beta-1 (TGF beta 1) in sections of developing bone in human osteophytes. The expression was related to the cellular activity of alkaline phosphatase to aid in the identification of pre-osteoblast populations. IL1 beta mRNA was localized in active osteoblasts within distinct areas of intramembranous ossification. However, the expression was sporadic and appeared to occur at a specific stage of the osteoblast life cycle. There was no IL1 beta mRNA expression in any cell types during endochondral ossification. IL6 mRNA expression was located within pre-osteoblasts and in newly differentiated and matrix-secreting osteoblasts; expression was absent or reduced in flattened, inactive osteoblasts. Weak or no IL6 expression was observed in chondroblasts and chondrocytes, respectively. However, there was a close association between IL6 mRNA expression and the differentiation of mesenchymal cells into osteoblasts. TGF beta 1 expression was localized to osteoblasts apposed to bone or cartilage matrix; the intensity of expression correlated with matrix secretion. Chondroblasts and chondrocytes expressed lower but significant levels of TGF beta 1 mRNA; the expression was lost with the progression to calcifying cartilage. The three cytokines studied were differentially expressed both temporally and spatially, suggesting different roles for each in osteoblast and chondrocyte function.



1996 ◽  
Vol 109 (5) ◽  
pp. 899-909 ◽  
Author(s):  
B. Capel ◽  
J.R. Hawkins ◽  
E. Hirst ◽  
D. Kioussis ◽  
R. Lovell-Badge

Cell cultures from the urogenital ridge have been established to facilitate the study of the regulation and downstream interactions of Sry in mammalian sex determination. Cells have been explanted from transgenic mice carrying a temperature sensitive SV40 large T-antigen, and established in ongoing cultures. Analysis of the cells in these cultures at the electron microscope level reveals multiple cell types that compare to the cell types found in vivo during this period of development. Primordial germ cells, that are simultaneously explanted in the course of these experiments, also survive in culture. The explants undergo a morphogenetic organization into branching cord-like structures when cells are trypsinized and plated in extracellular matrix (Matrigel). We analyzed the expression of a number of molecular markers of the fetal gonad during monolayer culture, during in vitro morphogenesis in Matrigel, and in clonal lines derived from the complex explants. This analysis included Sry which is found to be expressed in some cultures from XY urogenital ridges that have been maintained for as long as 8 months.



Development ◽  
1995 ◽  
Vol 121 (8) ◽  
pp. 2559-2567 ◽  
Author(s):  
P. Souza ◽  
M. Kuliszewski ◽  
J. Wang ◽  
I. Tseu ◽  
A.K. Tanswell ◽  
...  

The biological role of platelet-derived growth factor (PDGF)-AA in lung morphogenesis was investigated by incubating embryonic lung explants with phosphorothioate antisense PDGF-A oligonucleotides, which decreased PDGF-AA but not PDGF-BB protein content. Antisense PDGF-A oligonucleotides inhibited DNA synthesis. This inhibitory effect of antisense PDGF-A was reversed by the addition of exogenous PDGF-AA but not PDGF-BB. Morphometric analyses of antisense-treated cultures showed a significant reduction in lung size. The number of terminal buds of the lung explants was significantly decreased by antisense PDGF-A oligonucleotides. PDGF-AA but not PDGF-BB attenuated the inhibitory effect of antisense PDGF-A on early lung branching. Sense PDGF-A had no effect on DNA synthesis and early lung branching. Reverse transcriptase-polymerase chain reaction analysis revealed PDGF-A mRNA expression in the epithelial component of the embryonic lung, while message for PDGF alpha-receptor was expressed in the mesenchyme. Incubation of explants with neutralizing PDGF-AA antibodies also reduced DNA synthesis and early branching morphogenesis. We conclude that PDGF-AA and its receptor represent an important epithelial-mesenchymal interaction which plays a critical role in early lung branching morphogenesis.



2020 ◽  
Vol 21 (21) ◽  
pp. 8223
Author(s):  
Rajiv Kumar Sah ◽  
Jun Ma ◽  
Fatoumata Binta Bah ◽  
Zhenkai Xing ◽  
Salah Adlat ◽  
...  

Molecular and anatomical functions of mammalian Dip2 family members (Dip2A, Dip2B and Dip2C) during organogenesis are largely unknown. Here, we explored the indispensable role of Dip2B in mouse lung development. Using a LacZ reporter, we explored Dip2B expression during embryogenesis. This study shows that Dip2B expression is widely distributed in various neuronal, myocardial, endothelial, and epithelial cell types during embryogenesis. Target disruption of Dip2b leads to intrauterine growth restriction, defective lung formation and perinatal mortality. Dip2B is crucial for late lung maturation rather than early-branching morphogenesis. The morphological analysis shows that Dip2b loss leads to disrupted air sac formation, interstitium septation and increased cellularity. In BrdU incorporation assay, it is shown that Dip2b loss results in increased cell proliferation at the saccular stage of lung development. RNA-seq analysis reveals that 1431 genes are affected in Dip2b deficient lungs at E18.5 gestation age. Gene ontology analysis indicates cell cycle-related genes are upregulated and immune system related genes are downregulated. KEGG analysis identifies oxidative phosphorylation as the most overrepresented pathways along with the G2/M phase transition pathway. Loss of Dip2b de-represses the expression of alveolar type I and type II molecular markers. Altogether, the study demonstrates an important role of Dip2B in lung maturation and survival.



1995 ◽  
Vol 129 (1) ◽  
pp. 245-254 ◽  
Author(s):  
H A Franch ◽  
J W Shay ◽  
R J Alpern ◽  
P A Preisig

Although renal hypertrophy is often associated with the progressive loss of renal function, the mechanism of hypertrophy is poorly understood. In both primary cultures of rabbit proximal tubules and NRK-52E cells (a renal epithelial cell line), transforming growth factor beta 1 (TGF beta) converted epidermal growth factor (EGF)-induced hyperplasia into hypertrophy. TGF beta did not affect EGF-induced increases in c-fos mRNA abundance or cyclin E protein abundance, but inhibited EGF-induced entry into S, G2, and M phases. EGF alone increased the amount of hyperphosphorylated (inactive) pRB; TGF beta blocked EGF-induced pRB phosphorylation, maintaining pRB in the active form. To determine the importance of active pRB in TGF beta-induced hypertrophy, NRK-52E cells were infected with SV40 large T antigen (which inactivates pRB and related proteins and p53), HPV16 E6 (which degrades p53), HPV16 E7 (which binds and inactivates pRB and related proteins), or both HPV16 E6 and E7. In SV40 large T antigen expressing clones, the magnitude of EGF + TGF beta-induced hypertrophy was inhibited and was inversely related to the magnitude of SV40 large T antigen expression. In the HPV16-infected cells, EGF + TGF beta-induced hypertrophy was inhibited in E7- and E6E7-expressing, but not E6-expressing cells. These results suggest a requirement for active pRB in the development of EGF + TGF beta-induced renal epithelial cell hypertrophy. We suggest a model of renal cell hypertrophy mediated by EGF-induced entry into the cell cycle with TGF beta-induced blockade at G1/S, the latter due to maintained activity of pRB or a related protein.



Author(s):  
Moning Liu ◽  
Lixia Zhao ◽  
Zixin Wang ◽  
Hong Su ◽  
Tong Wang ◽  
...  

Pluripotent stem cells (PSCs) have the potential to differentiate to all cell types of an adult individual and are useful for studying mammalian development. Establishing induced pluripotent stem cells (iPSCs) capable of expressing pluripotent genes and differentiating to three germ layers will not only help to explain the mechanisms underlying somatic reprogramming but also lay the foundation for the establishment of sheep embryonic stem cells (ESCs) in vitro. In this study, sheep somatic cells were reprogrammed in vitro into sheep iPSCs with stable morphology, pluripotent marker expression, and differentiation ability, delivered by piggyBac transposon system with eight doxycycline (DOX)-inducible exogenous reprogramming factors: bovine OCT4, SOX2, KLF4, cMYC, porcine NANOG, human LIN28, SV40 large T antigen, and human TERT. Sheep iPSCs exhibited a chimeric contribution to the early blastocysts of sheep and mice and E6.5 mouse embryos in vitro. A transcriptome analysis revealed the pluripotent characteristics of somatic reprogramming and insights into sheep iPSCs. This study provides an ideal experimental material for further study of the construction of totipotent ESCs in sheep.



Development ◽  
1987 ◽  
Vol 100 (1) ◽  
pp. 95-105
Author(s):  
JH Russ ◽  
JD Horton

This paper describes in vitro and in vivo attempts to deplete the 4- to 8-month-old Xenopus laevis (J strain) thymus of its lymphocyte compartment. Gamma irradiation (2-3000 rad) of the excised thymus, followed by two weeks in organ culture, is effective in removing lymphocytes, but causes drastic reduction in size and loss of normal architecture. In contrast, in vivo whole-body irradiation (3000 rad) and subsequent in situ residence for 8-14 days proves successful in providing a lymphocyte-depleted froglet thymus without loss of cortical and medullary zones. In vivo-irradiated thymuses are about half normal size, lack cortical lymphocytes, but still retain some medullary thymocytes; they show no signs of lymphocyte regeneration when subsequently organ cultured for 2 weeks. Light microscopy of 1 micron, plastic-embedded sections and electron microscopy reveal that a range of thymic stromal cell types are retained and that increased numbers of cysts, mucous and myoid cells are found in the thymus following whole-body irradiation. In vivo-irradiated thymuses are therefore suitable for implantation studies exploring the role of thymic stromal cells in tolerance induction of differentiating T lymphocytes.



2017 ◽  
Vol 95 (3) ◽  
pp. 421-427 ◽  
Author(s):  
Peter K. Eck ◽  
Christopher Corpe ◽  
Mark A. Levine

The two membrane transporters Slc23a1 and Slc23a2 mediate ascorbic acid uptake into cells. We recently determined the key role of Slc23a1 in renal re-absorption of ascorbic acid in a knockout mouse model. However, the renal spatial and temporal expression patterns of murine Slc23a1 and Slc23a2 are not defined. This study utilizes database evidence combined with experimental confirmation via in-situ hybridization to define the spatial and temporal expression of Slc23a1 in the murine kidney. Slc23a1 is expressed in the early proximal tubule, but not in its precursors during embryonic development, and exclusive proximal tubular expression persists throughout the animal’s lifetime. In contrast, Slc23a2 is uniformly expressed in metabolic cell types such as stromal cells. The expression patterns appear to be conserved from rodent lineages to humans.



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