Differential effect of hypertonic initiation block on the synthesis of collagen chains by cultured chick embryo cells

Pawlowski, Philip J.

doi:10.1021/bi00530a006

Cited by 15 publications

(2 citation statements)

References 21 publications

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“…The N-terminal propeptide of type I collagen appears to exert a specific inhibitory effect on translation of type I collagen mRNAs both in vitro and in cultured cells (23,41,69); a similar role has been described for the N-terminal propeptide of type II collagen (42). In cultured fibroblasts, hypertonicity of the culture medium also appears to preferentially inhibit utilization of type I collagen mRNAs (44). It is not yet clear whether these mechanisms play a role in regulating collagen gene expression in vivo.…”

Section: =3 A2(l)mentioning

confidence: 75%

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

Focht¹,

Adams²

1984

Mol. Cell. Biol.

100

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We analyzed the control of type I collagen synthesis in four kinds of differentiated cells from chicken embryos which synthesize very different amounts of the protein. Tendon, skin, and smooth muscle cells were found to have identical amounts of type I collagen RNAs; however, the RNAs had inherently different translatabilities, which were observed both in vivo and in vitro. Chondrocytes also had substantial amounts of type I collagen RNAs, even though they directed no detectable synthesis of the protein either in vivo or in vitro. Type I collagen RNAs in chondrocytes display altered electrophoretic mobilities, suggesting that in these cells the reduction in translational efficiency may be mediated in part by changes in the RNA structure. These data indicate that control of type I collagen gene expression is a complex process which is exerted at both transcriptional and posttranscriptional levels.The collagens are the predominant protein class in vertebrate connective tissue. In conjunction with other components of the extracellular matrix, such as proteoglycans and cell surface proteins, they are the major determinants of tissue structure and function. Type I collagen, the major collagen of bone and tendon, as well as soft tissue such as skin and lung, is the most abundant. The amount of type I collagen synthesized by a given cell varies widely and appears to be determined by the differentiated phenotype of the cell (14,15,22). In many cases, differences in the amount of type I collagen synthesis appear to reflect differences in steady-state type I collagen mRNA levels, implying primary control by transcription or RNA stabilization (1, 3, 19, 24, 37, 45, 48-52, 55, 56). Results of recent experiments in several laboratories, however, have suggested that the control of type I collagen synthesis is far more complex and may involve control at the levels of translation and specific protein degradation (2, 12, 23, 40-42, 44, 49, 61, 62, 69).In the experiments described below, we analyzed the rate of type I collagen synthesis in four populations of differentiated cells (tendon fibroblasts, skin fibroblasts, smooth muscle cells, and chondrocytes), which synthesize vastly different amounts of the protein. Our data show that although there are some differences in steady-state RNA levels, these differences cannot account for the observed variation in the rate of protein synthesis. Although the amounts of type I collagen mRNAs in tendon, skin, and smooth muscle cells are virtually identical, these RNAs appear to have inherently different translatabilities; these differences in translatability are observed not only in vivo, but also in heterologous translation systems directed by purified RNAs. This translational variation could be due either to structural differences in the type I collagen mRNAs themselves or to other RNAs in the population which serve a regulatory function.Examination of type I collagen RNAs from chondrocytes suggests that some alterations in translational efficiency may be mediated by changes in the stru...

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Section: =3 A2(l)mentioning

confidence: 75%

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

Focht¹,

Adams²

1984

Mol. Cell. Biol.

100

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“…In most (34,48), albeit not all (10), cases, viral translation is more resistant to excess NaCl than is host translation. The distinction is not simply between cellular and viral mRNAs, however, because the spectrum of mRNAs from a particular virus shows a gradient of resistance (46), and cellular mRNAs are not uniformly sensitive (47,51). Cellular heat shock mRNAs are particularly resistant to hypertonic shock (14,19,23,45).…”

Section: Methodsmentioning

confidence: 99%

Leader length and secondary structure modulate mRNA function under conditions of stress.

Kozak

1988

Mol. Cell. Biol.

158

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Simian virus 40-based plasmids that direct the synthesis of preproinsulin in cultured monkey cells were used to study the effects of mRNA structure on translational efficiency. Lengthening the leader sequence enhanced translation in this system. The enhancement was most obvious when an unstructured sequence (two, four, or eight copies of the oligonucleotide AGCTAAGTAAGTAAGTA) was inserted upstream from a region of deliberate secondary structure; the degree of enhancement was proportional to the number of copies of the inserted oligonucleotide. Lengthening the leader sequence on the 3' side of a stem-and-loop structure, in contrast, did not offset the potentially inhibitory effect of the hairpin structure. Both the facilitating effect of length and the inhibitory effect of secondary structure were demonstrated most easily under conditions of mRNA competition, which was brought about by an abrupt shift in the tonicity of the culture medium. These experiments suggest a simple structural basis for the long-recognized differential response of viral and cellular mRNAs to hypertonic stress. The fact that the translatability of structure-prone mRNAs varies with changes in the environment may also have general implications for gene expression in eucaryotic cells.A recent survey of vertebrate mRNA sequences (37) revealed that 75% of the characterized mRNAs have 5'-untranslated sequences that range in length from 20 to 100 nucleotides. About one-fourth of the mRNAs surveyed had leader sequences in the range of 100 to 300 nucleotides, and there were rare examples of mRNAs with 5'-noncoding sequences as long as 1,000 nucleotides (52). It is not clear how leader length affects translational efficiency, since both extremes are found among efficiently translated cellular and viral mRNAs. For example, the tripartite leader sequence on adenovirus late mRNAs (63) and the leader sequences on some heat shock mRNAs (27) are more than 200 nucleotides long, while the mRNAs that encode adenovirus polypeptide IX and the N protein of vesicular stomatitis virus have leader sequences of only 24 and 13 nucleotides, respectively (13, 63). Because length is not the only variable when one natural mRNA is compared with another, however, the question of how leader length affects translational efficiency cannot be decided by inspecting natural mRNAs; a more systematic approach is needed. The question has been addressed experimentally in two preliminary studies, one which reported no effect of expanding the leader sequence (25) and the other which reported that inserting an extra 152 nucleotides lowered the translational yield (4). The experiments reported here indicate that expanding the leader sequence on a chimeric preproinsulin mRNA enhances its translation under conditions of mRNA competition which occur, for example, when cells in culture are shifted to hypertonic medium.The "wild-type" mRNA used for these studies consisted of the rat preproinsulin TI-coding sequence linked to the 5'-untranslated sequence of the message that encodes simian vi...

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Sodium ion modulates collagen types in human fibrolastic cells in culture

Hata

Sunada

Nagai

1983

Biochemical and Biophysical Research Communications

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Differential effect of hypertonic initiation block on the synthesis of collagen chains by cultured chick embryo cells

Cited by 15 publications

References 21 publications

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

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

Leader length and secondary structure modulate mRNA function under conditions of stress.

Sodium ion modulates collagen types in human fibrolastic cells in culture

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