Tissue specificity of type I collagen gene expression is determined at both transcriptional and post-transcriptional levels.

Focht, Richard J.; Adams, Sherrill L.

doi:10.1128/mcb.4.9.1843

Cited by 100 publications

(57 citation statements)

References 34 publications

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“…Still the cells synthesized only type I collagen. Our data, in agreement with findings of other groups (12,14,21,23), might suggest a translational regulation of the type I collagen expression during the in vitro differentiation process of chondrocytes from dedifferentiated cells.…”

Section: Discussionsupporting

confidence: 93%

In vitro development of hypertrophic chondrocytes starting from selected clones of dedifferentiated cells.

Quarto

Dozin

Tacchetti

et al. 1990

The Journal of Cell Biology

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Abstract. Single cells from enzymatically dissociated chick embryo tibiae have been cloned and expanded in fresh or conditioned culture media. A cloning efficiency of ,,o13% was obtained using medium conditioned by dedifferentiated chondrocytes. A cloning efficiency of only 1.4% was obtained when conditioned medium from hypertrophic chondrocytes was used, and efficiencies of essentially 0 were found with fresh medium or medium conditioned by J2-3T3 mouse fibroblasts. Cell clones were selected by morphological criteria and clones showing a dedifferentiated phenotype (fibroblast-like) were further characterized. Out of 38 clones analyzed, 17 were able to differentiate to the hypertrophic chondrocyte stage and reconstitute hypertrophic cartilage when placed in the appropriate culture conditions. Cells from these clones expressed the typical markers of chondrocyte differentiation, i.e., type II and type X collagens. Clones not undergoing differentiation continued to express only type I collagen. Hypertrophic chondrocytes from differentiating clones were analyzed at the single cell level by immunofluorescence; all the cells were positive for type X collagen, while ,x,50% of them showed positivity for type II collagen. (6,19,24). Chondrocytes from Hamburger and Hamilton stage 28-30 (17) chick embryo tibiae dedifferentiate when cultured on plastic dishes. These cells, as well as dedifferentiated chondrocytes from another source (4), maintain the dedifferentiated phenotype as long as the conditions for the cell attachment to the plastic are kept. When the same cells are transferred into suspension culture, they resume the chondrocytic phenotype and mature to hypertrophic chondrocytes through a transient stage of cell aggregation (7). This process is accompanied by an increase in the length of the cell cycle and in the number of quiescent and degenerating cells (16), as well as by a modulation in the transcriptional activity of the collagen genes (9). We have recently reported the identification, purification, and characterization of a novel, low molecular weight protein, named Ch21, expressed and secreted by the in vitro differentiating chondrocytes at a late stage of development (11). When dedifferentiated cells are cultured in suspension in the constant presence of ascorbic acid, they organize their own extracellular matrix and develop into a tissue closely resembling calcifying hypertrophic cartilage (28,29).The heterogeneity of the dedifferentiated cell population did not allow us to definitely state whether the cells followed successive stages of differentiation or the culture conditions made a selection of cell subpopulations. To answer this important question we selected clones of dedifferentiated cells to follow the respective behavior of each clone in terms of morphology and collagen phenotype in the different culture conditions. We show that up to 45 % of the cell populations obtained from single cloned dedifferentiated cells are still able to differentiate to hypertrophic chondrocytes and to reconstitute hyp...

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Section: Discussionsupporting

confidence: 93%

In vitro development of hypertrophic chondrocytes starting from selected clones of dedifferentiated cells.

Quarto

Dozin

Tacchetti

et al. 1990

The Journal of Cell Biology

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“…An unexpected finding of considerable interest was the presence of low levels of type II collagen mRNA in the cytoplasm of prechondrogenic mesenchymal cells at the earliest stages of limb development, indicating the type II collagen gene is being transcribed well before the onset of overt cartilage differentiation and the accumulation of detectable amounts of type II collagen. Furthermore, our results are consistent with other recent studies (1,9,31) indicating that type I collagen gene expression during chondrogenesis is regulated, at least in part, at the translational level, since substantial amounts of type I collagen mRNAs are present in the cytoplasm of well-differentiated chondrocytes which do not synthesize detectable amounts of type I collagen.…”

Section: T He Onset Of Cartilage Differentiation In the Developingsupporting

confidence: 93%

“…Evidence for the translational regulation of type I collagen gene expression in chondrocytes has also recently been provided by other investigators. Type I collagen mRNAs have been detected in limb and sternal cartilage (22); in the cytoplasm of cultured sternal chondrocytes (31); and in cultured vertebral chondrocytes, which also do not synthesize type I collagen (1,9).…”

Section: Discussionmentioning

confidence: 99%

“…In this regard, it should be emphasized that our hybridizations and washes were performed under very stringent conditions, i.e. hybridizations being done in 50% formamide at 55"C, and multiple washes being done in 0.1X SSC at 55"C. These conditions are, in general, as stringent as those that several investigators have shown prevent cross-hybridization between several type II collagen cDNAs and type I collagen mRNAs, or between type I collagen cDNAs and type II collagen mRNAs (8,9,26,37). To directly test the possibility of cross-hybridization, aliquots of cytoplasmic extracts of stage 18/19 and stage 25 subridge mesenchymal cells and aliquots of purified calvaria RNA, which contains large quantities of both al(I) and a2(I) mRNAs, were hybridized with the type II collagen cDNA probe.…”

Section: Type H Collagen Mrna During Chondrogenesismentioning

confidence: 99%

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Collagen gene expression during limb cartilage differentiation.

Kosher¹,

Kulyk²,

Gay³

1986

The Journal of Cell Biology

227

128

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Abstract. As limb mesenchymal cells differentiate into chondrocytes, they initiate the synthesis of type II collagen and cease synthesizing type I collagen. Changes in the cytoplasmic levels of type I and type II collagen mRNAs during the course of limb chondrogenesis in vivo and in vitro were examined using cloned cDNA probes. A striking increase in cytoplasmic type II collagen m R N A occurs coincident with the crucial condensation stage of chondrogenesis in vitro, in which prechondrogenic mesenchymal cells become closely juxtaposed before depositing a cartilage matrix. Thereafter, a continuous and progressive increase in the accumulation of cytoplasmic type II coUagen m R N A occurs which parallels the progressive accumulation of cartilage matrix by ceils. The onset of overt chondrogenesis, however, does not involve activation of the transcription of the type II collagen gene. Low levels of type II collagen m R N A are present in the cytoplasm of prechondrogenic mesenchymal cells at the earliest stages of limb development, well before the accumulation of detectable levels of type II collagen. Type I collagen gene expression during chondrogenesis is regulated, at least in part, at the translational level. Type I collagen mRNAs are present in the cytoplasm of differentiated chondrocytes, which have ceased synthesizing detectable amounts of type I collagen. T HE onset of cartilage differentiation in the developinglimb is characterized by a transient cellular condensation or aggregation process in which prechondrogenic mesenchymal cells become closely juxtaposed to one another before initiating cartilage matrix deposition. During this process, a cell-cell interaction, cell shape change, or some other event occurs which is necessary to trigger the chondrogenic differentiation of the cells (15). The critical condensation process may be initiated, at least in part, by a progressive decrease in the accumulation of extracellular hyaluronate (20,35). Fibronectin and type I collagen have been implicated in the cell-cell interaction occurring during condensation (7, 21, 34). Prostaglandin-mediated elevations in cAMP levels during condensation are involved in regulating chondrogenesis (3, 6, 11, 14, 16-18, 32, 33). A change in the shape of the cells from a flattened mesenchymal morphology to a rounded configuration also plays an important role in the process (2, 41).Although considerable insight has been gained into the extracellular influences and intracellular regulatory molecules that are involved in regulating limb chondrogenesis, virtually nothing is known about the molecular mechanisms by which these factors directly influence the changes in gene activity that occur during cartilage differentiation. Prechondrogenic limb mesenchymal cells synthesize type I collagen (36). As the cells differentiate into chondrocytes, they initiate the synthesis of cartilage-characteristic type II collagen and cease synthesizing type I collagen (36). Thus the conversion of mesenchymal chondrogenic progenitor cells into chondrocytes i...

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“…By analogy, in other conditions in which the levels of procollagen mRNAs are suppressed parallel to suppression of collagen protein synthesis, such as infection with Rous sarcoma virus, the effect is probably exerted at the level of transcription [30,31]. On the other hand, Focht and Adams [32] have recently shown that control of type I collagen gene expression may be exerted at both transcrtptional and posttranscrtptional levels. Of interest is our finding in the synovial cell preparation examined that the ratio of al(I)/cu2(1) procollagen mRNAs was considerably less than 2, the ratio predicted and observed in previous studies utilizing these cDNA probes [20] and confirmed by us in the normal strain of fibroblasts.…”

Section: Discussionmentioning

confidence: 99%

Immune interferon inhibits collagen synthesis by rheumatoid synovial cells associated wth decreaded levels of the procollagen mRNAs(FEBS 2156)

Stephenson¹,

Krane²,

Amento³

et al. 1985

FEBS Letters

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Tissue specificity of type I collagen gene expression is determined at both transcriptional and post-transcriptional levels.

Cited by 100 publications

References 34 publications

In vitro development of hypertrophic chondrocytes starting from selected clones of dedifferentiated cells.

In vitro development of hypertrophic chondrocytes starting from selected clones of dedifferentiated cells.

Collagen gene expression during limb cartilage differentiation.

Immune interferon inhibits collagen synthesis by rheumatoid synovial cells associated wth decreaded levels of the procollagen mRNAs(FEBS 2156)

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