Fibroblasts as an Experimental Tool in Metabolic and Hormone Studies

Morell, B; Froesch, E. R.

doi:10.1111/j.1365-2362.1973.tb00338.x

Cited by 104 publications

(11 citation statements)

References 30 publications

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“…This agrees with our earlier findings regarding the effects of NSILA on replication, and synthesis of protein, RNA, and DNA, in 12-day chick embryo fibroblasts in secondary culture (5,26). The sensitivity of chick embryo sternum to partially purified NSILA, and to homogeneous NSILA-I or NSILA-II, is similar to that of the cultured fibroblasts.…”

Section: Discussionsupporting

confidence: 93%

“…This is as much stimulation as can be obtained with normal rat serum supplemented with T3 (not shown). The concentration of the serum from hypophysectomized rats did not influence the results between 5 and 20%. Since serum contains a specific binding protein for NSILA (18), it seemed possible that NSILA might stimulate sulfation only in the bound form.…”

Section: Resultsmentioning

confidence: 76%

“…The insulin-like properties of NSILA have been reviewed recently (3,4). Growth-promoting effects of NSILA have been demonstrated in chick embryo and human fibroblast cultures (5,6); these appear to be mediated by a highly specific membrane receptor for NSILA (7). NSILA is also a potent sulfation factor in rat costal cartilage (8).…”

mentioning

confidence: 99%

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Nonsuppressible insulin-like activity and thyroid hormones: major pituitary-dependent sulfation factors for chick embryo cartilage.

Froesch¹,

Zapf²,

Audhya³

et al. 1976

Proc. Natl. Acad. Sci. U.S.A.

106

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Serum from hypothyroid hypophysectomized rats did not stimulate sulfation or incorporation of amino acids into chick embryo sterna. When such rats were treated for a short time with growth hormone (somatotropin), their serum stimulated incorporation both of sulfate and of amino acids. The different actions of the two types of sera were not due to changes in thyroid state. The results support the existence in serum of a sulfation factor for chick embryo cartilage that is dependent upon growth hormone.Highly purified preparations of nonsuppressible insulin-like activity from human serum stimulated incorporation of amino acids, and of uridine into RNA, in chick embryo sterna in vitro; chondrocytes prepared from this tissue had specific high-affinity binding sites for this insulin-like activity. However, sulfate incorporation was stimulated very little, unless serum from hypothyroid hypophysectomized rats was also present. When L-3,5,3'-triiodothyronine was added as well, the stimulation was enhanced further. From these and other experiments, we conclude that (i) nonsuppressible insulin-like activity or a closely related peptide is the growth-hormone-dependent growth and sulfation factor for chick embryo cartilage; (ii) a second, unidentified factor must be present for the insulin-like activity to stimulate sulfation; and (jii) stimulation of sulfation by thyroid hormones in vitro is additive to that of nonsuppressible insulin-like activity.Nonsuppressible insulin-like activity (NSILA) of serum is attributable to two peptides, NSILA-I and NSILA-II, which have a molecular weight of 5800 and are presently being characterized in detail (ref. 2; R. Rinderknecht, J. Zapf, and R. E. Humbel, in preparation). The insulin-like properties of NSILA have been reviewed recently (3, 4). Growth-promoting effects of NSILA have been demonstrated in chick embryo and human fibroblast cultures (5, 6); these appear to be mediated by a highly specific membrane receptor for NSILA (7). NSILA is also a potent sulfation factor in rat costal cartilage (8).Thyroid hormones appear to be responsible in part for the stimulation by normal serum of sulfation in chick embryo cartilage (9). Stimulation of sulfation by L-3,5,3'-triiodothyronine (T3) and serum reflects increased synthesis of at least the major proteoglycan in the tissue (10). The effect of serum on sulfation in this tissue has also been attributed to two small peptides, which have been named somatomedins Al and A2 (11). These two peptides are clearly distinct from NSILA since they have a different amino acid composition and apparently do not contain disulfide bridges, which are essential for the Abbreviations: NSILA, acid-soluble insulin-like activity from human serum not suppressible by antibody against insulin; T3, L-3,5,3'-triiodothyronine; GH, growth hormone (somatotropin); U, unit of insulin-like activity relative to porcine insulin.

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Section: Discussionsupporting

confidence: 93%

Section: Resultsmentioning

confidence: 76%

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Nonsuppressible insulin-like activity and thyroid hormones: major pituitary-dependent sulfation factors for chick embryo cartilage.

Froesch¹,

Zapf²,

Audhya³

et al. 1976

Proc. Natl. Acad. Sci. U.S.A.

106

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“…In the first region the residues equivalent to B1-B5 are quite different; in particular B5 His (4,26), although insulin is more potent in stimulating acute metabolic effects (3)(4)(5). These different effects probably arise through the interaction of the polypeptides with two separate membrane receptors, one of which has a higher affinity for IGF and the other a higher affinity for insulin (9).…”

Section: Resultsmentioning

confidence: 99%

Insulin-like growth factor: a model for tertiary structure accounting for immunoreactivity and receptor binding.

Blundell¹,

Bedarkar²,

Rinderknecht³

et al. 1978

Proc. Natl. Acad. Sci. U.S.A.

260

137

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A model for the three-dimensional structure of insulin-like growth factor (IGF) is proposed based on the close sequence homology of IGF with insulin, the tertiary structure of which is known. The IGF molecule is postulated to have an insulin-like main chain conformation for residues equivalent to B6-B27 and A1-A21 and a hydrophobic core nearly identical to that of insulin. A short connecting peptide of twelve residues and an extension at the COOH-terminus are easily accommodated on the molecular surface. MATERIALS AND METHODS The model was built in several stages. The proposed structure was first constructed using Lapquip model parts at a scale of 1 cm = 1 A. This was examined for unfavorable intramolecular contracts and readjusted before the coordinates of each atom were read off using a mechanical device. The approximate coordinates were then regularized using the "modelfit" computer program of Isaacs et al (12), and bond lengths and angles and other intramolecular distances were calculated using an IBM 360/65 computer. The model was then displayed on a computer graphics system (Digital Equipment Corp. graphics with a PDPll computer) using programs written by D. Richardson, P. Pauling, and C. Chothia, and adjustments were made using the interactive facilities of the graphics system to optimize the intramolecular distances. Finally, the model was regeometricized using "modelfit" and stereo pairs of the model were generated in hard copy. RESULTS AND DISCUSSIONThree-dimensional model for IGF I Table 1 shows the sequences of human IGF I, IGF II, and porcine insulin aligned so that the maximum homology is obtained. The numbering for the insulin A and B chains is indicated, as is the numbering for the IGF I polypeptide. The sequence of the IGF connecting peptide of 12 residues is also included, but because this shows no homology with the proinsulin connecting peptide, the latter is omitted. IGF I has an extension of eight residues at the COOH terminus of the A chain. Table 2 gives the differences in numbers of amino acids between the 51 amino acids of porcine insulin and the equivalent residues of other insulins, the protein hormone relaxin (13)(14)(15), which also appears to be homologous with insulin, and IGF.The sequence comparison shows a close homology for residues 5-25 of IGF (B6-B26 of insulin) and 42-61 (A1-A20). The arrangement of cystines is identical in IGF and insulin, and glycines 7 (B8), 19 (B20), and 22 (B23), which have dihedral angles that are disallowed for residues with side chains, are conserved, so that the polypeptide backbone can assume the same three-dimensional structure as insulin. We began by building the sequence 5-26 and 42-61 into an insulin-like structure. This conformation is shown schematically in Fig. 1. Residues 8-18 (B9-B19) and [43][44][45][46][47][48] (A2-A7) are right-handed a-helices and residues 54-60 (A13-A19) formed a less organized right-handed helix. Cys 47 and 52 (A6 and All) and Cys 61 and 18 (A20 and B19) have their disulfides placed in the core, while the Cys ...

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“…Such a mitogenic effect of high concentrations of insulin has been demonstrated for various other cell types in vitro [3]. In fibroblast cultures [4] the growth enhancing capacity of insulin is mediated by receptors which bind insulin with a low affinity but have a high affinity for the insulinlike growth factors (IGF I and IGF II) [5]. To test the hypothesis that the effect of insulin on colony formation of CFU-e is due to a direct effect of IGF we have examined the influence of IGF I on the growth of CFU-e in a serum-free culture system.…”

Section: Introductionmentioning

confidence: 99%

A new candidate for the regulation of erythropoiesis

1982

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The effect of pure human insulin-like growth factor I (IGF I) on the colony formation of late stage erythroid precursor cells (CFU-e) from fetal mouse liver and adult bone marrow was studied in a serumfree culture system. We found that IGF I in physiological concentrations stimulated erythroid colony formation. The combined effect of IGF I and erythropoietin was smaller than the sum of their single effects. The number of colonies induced by IGF I was linearly dependent on the number of plated cells. Our results indicate that IGF I is the first clearly defined mitogen that stimulates the late stages of erythroid differentiation independently of erythropoietin. Insulin-like growth factor Somatomedin Erythroid differentiation Erythroid precursor cellCell structure

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Fibroblasts as an Experimental Tool in Metabolic and Hormone Studies

Cited by 104 publications

References 30 publications

Nonsuppressible insulin-like activity and thyroid hormones: major pituitary-dependent sulfation factors for chick embryo cartilage.

Nonsuppressible insulin-like activity and thyroid hormones: major pituitary-dependent sulfation factors for chick embryo cartilage.

Insulin-like growth factor: a model for tertiary structure accounting for immunoreactivity and receptor binding.

A new candidate for the regulation of erythropoiesis

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