New Preparative Schedule and Further Characterization of a Thymocyte Specific Growth Factor from Calf Thymus

Söder, Olof; Ernström, Ulf

doi:10.1159/000234855

Cited by 5 publications

(6 citation statements)

References 7 publications

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“…The purification schedule has recently been published in detail [6). An extract was prepared from pooled calf thymuses by sequen tial steps of solvent extractions and precipitations.…”

Section: Preparation O F Thymic Growth Factormentioning

confidence: 99%

“…In previous papers, we have reported on the biochemical and functional properties of a thymic factor with ability to induce DNA synthesis specifically in immunologically in competent immature thymocytes [3][4][5]. The factor was shown to be biochemically and functionally distinct from other lymphocyte growth factors and from thymic differentiation hormones [6,7]. Kinetic studies showed that the thymic factor stimulated DNA syn thesis with a peak effect 4-8 h after start of culture [4,5], indicating that the target cells were Gl thymocytes which were influenced to initiate DNA synthesis.…”

Section: Introductionmentioning

confidence: 99%

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Recruitment of Thymocytes from G1 into S Phase by a Thymic Factor

Söder¹,

Ernström²

1984

Int Arch Allergy Immunol

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A thymic factor previously shown to stimulate the DNA synthesis of immature thymocytes was found to recruit G1 cells synchronously into S phase within 1.5–2 h. The S + G2 + M duration of the cultured thymocytes was not affected. In the absence of the thymic factor, the responding thymocytes seemed to be blocked in G1 at a putative restriction point 1.5 h prior to S phase. When the addition of the thymic factor to cultured cells was delayed, the responsiveness rapidly declined, indicating that target cells were transferred into an unresponsive state. A stimulating effect of the DNA synthesis of cultured thymocytes was obtained also after a transient exposure to the thymic factor for 2–3 h. The stimulating activity was completely absorbed from the medium by incubation with thymocytes at both 4 and 37 °C, but not by lymph node lymphocytes which are unresponsive to the thymic factor. Our interpretation of the results is that the thymic factor acts on thymocytes in G1, triggering the responsive cells via membrane receptors to proceed from G1 into S phase. The thymic factor is proposed to be a progression factor for the rapidly cycling immature thymocytes and to be involved in the regulation of the intense thymic growth in vivo.

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“…The purification schedule has recently been published in detail [6). An extract was prepared from pooled calf thymuses by sequen tial steps of solvent extractions and precipitations.…”

Section: Preparation O F Thymic Growth Factormentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Recruitment of Thymocytes from G1 into S Phase by a Thymic Factor

Söder¹,

Ernström²

1984

Int Arch Allergy Immunol

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“…Calf thymus extract was prepared and purified as described in a previous paper [9). The purified active material from the Bio-Gel P-4 column was used in an amount resulting in maximal stimula tion of DN A synthesis in thymcocytes.…”

Section: Preparation O F Thymocyte Specific Growth Factormentioning

confidence: 99%

“…Crude extract [9] was prepared from 20 g of each guinea pig tissue and calf thymus and separated on Sephadex G 50 fine. Fractions were pooled, lyophilized and subjected to Bio-Gel P-4 chromatog raphy.…”

Section: Preparation O F Different Tissue Extractsmentioning

confidence: 99%

“…Organ extracts from guinea pigs were prepared and purified according to the schedule used for calf thymus [9], The final material obtained by TLC was tested for stimulating activity on thymocyte DNA synthesis. Active material with identical chromato graphic behaviour was demonstrated in calf thymus, guinea pig thymus and spleen ( fig.…”

Section: Search For Thymocyte Growth-stimulating Activity In Various mentioning

confidence: 99%

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Search for Thymocyte Growth-Stimulating Activity in Extracts of Different Tissues and among Established Growth Factors and Thymic Maturation Hormones

Söder¹,

Ernström²

1983

Int Arch Allergy Immunol

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A thymocyte specific growth factor has previously been prepared from calf thymus. Similar activity is now shown to be present in thymus and spleen of guinea pigs, but not in lymph nodes, liver and kidney. Purified thymic maturation hormones, interleukins and several growth factors for other cell types than lymphocytes were tested and found not to stimulate DNA synthesis of thymocytes. A slight activity was found in thymosin fraction 5, known to contain at least 35 polypeptides. Our factor lacked comitogenic effect when tested in combination with concanavalin A (ConA) and phytohemagglutinin, did not promote continuous growth of ConA-induced lymphoblasts and did not affect the cyclic AMP level of thymocytes. The data indicate that our factor is functionally distinct from the purified hormones and defined factors tested.

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Purification of thymocyte growth peptide (TGP) from sheep thymus. Relationship to FTS/thymulin

1990

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Thymocyte growth peptide (TGP) initiates DNA synthesis in immature thymocytes and has previously been characterized as an acidic peptide isolated from calf thymus. We now report the isolation of TGP from sheep thymus and show it to be a nonapeptide with a large N-terminal blocking moiety characterized by high UV absorbance. The amino acid composition is identical to FTS, consisting of 2 Gly, 2 Ser, 2 Glx, 1 Ala, 1 Lys, 1 Asx. In contrast to FTS, TGP is acidic with an apparent isoelectric point of 4.2 and a high UV absorbance at 270-280 nm. Reverse phase chromatography of TGP at an acidic pH results in a change of the molecule and the appearance of two new compounds TGP-A and TGP-B, both with less than 50% of the original TGP activity. Full activity could be restored by the addition of ZnCl2 to TGP-A. Both TGP-A and B have some amino acid composition and high UV absorbance as native TGP. We propose that TGP consists of a non-peptide moiety bound to the N-terminal of the nonapeptide Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn and that the active molecule is stabilized by Zn2+.

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New Preparative Schedule and Further Characterization of a Thymocyte Specific Growth Factor from Calf Thymus

Cited by 5 publications

References 7 publications

Recruitment of Thymocytes from G1 into S Phase by a Thymic Factor

Recruitment of Thymocytes from G1 into S Phase by a Thymic Factor

Search for Thymocyte Growth-Stimulating Activity in Extracts of Different Tissues and among Established Growth Factors and Thymic Maturation Hormones

Purification of thymocyte growth peptide (TGP) from sheep thymus. Relationship to FTS/thymulin

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