ABSTRACT
We show that ptma, a single copy gene found in all organisms investigated so far, is duplicated in zebrafish. The two genes, ptmaa and ptmab, are individually controlled as indicated by their different expression patterns during embryonic development. Only the ptmab transcript is observed at 4 and 8 hpf of development in all embryonic cells, whereas both genes are expressed at later stages as revealed by in situ hybridization studies. In most cases, the two genes are expressed in the same territories, but only the ptmaa transcript was found in the trigeminal ganglion and in endodermal pouches. In the eye, at 72 hpf, the ptmaa and ptmab transcripts were found in amacrine cells, whereas only the ptmab transcript appeared in horizontal cells. The existence of two prothymosin genes indicates that their function in cell proliferation and differentiation is more complex in fishes than in mammals.
Subject(s)
Gene Duplication , Gene Expression Regulation, Developmental , Protein Isoforms/genetics , Protein Precursors/genetics , Thymosin/analogs & derivatives , Zebrafish Proteins/genetics , Zebrafish/embryology , Zebrafish/metabolism , Amino Acid Sequence , Animals , Humans , In Situ Hybridization , Molecular Sequence Data , Phylogeny , Protein Isoforms/classification , Protein Isoforms/metabolism , Protein Precursors/classification , Protein Precursors/metabolism , Sequence Alignment , Thymosin/classification , Thymosin/genetics , Thymosin/metabolism , Zebrafish/anatomy & histology , Zebrafish/genetics , Zebrafish Proteins/classification , Zebrafish Proteins/metabolismABSTRACT
Thymosin beta 4 is a major actin monomer binding protein present at high concentration in many vertebrate cells and cell lines. The interactions of actin with thymosin beta 4, actobindin and profilin are compared. Nine beta-thymosins have been identified; six have been shown to bind to actin. Regulation of the synthesis of thymosin beta 10 and thymosin beta 4 has been found in brain development and after stimulation of several cell types, respectively. The extracellular effects of thymosin beta 4 still need clarification.
Subject(s)
Contractile Proteins , Microfilament Proteins/metabolism , Thymosin/metabolism , Actins/metabolism , Amino Acid Sequence , Animals , Carrier Proteins/metabolism , Gene Expression Regulation , Humans , Mice , Microfilament Proteins/genetics , Molecular Sequence Data , Multigene Family , Phylogeny , Profilins , Protozoan Proteins , Rats , Sequence Alignment , Sequence Homology, Amino Acid , Species Specificity , Thymosin/classification , Thymosin/geneticsABSTRACT
A new polypeptide termed thymosin beta 12 has been isolated from perch liver and its primary structure elucidated. This polypeptide contains 43 amino acid residues with a molecular weight of 4822 Da. The content of thymosin beta 12 from perch liver has been determined as 43 micrograms/g of tissue. The amino-terminal end of this polypeptide is blocked by an acetyl group as deciphered by fast-atom bombardment mass spectrometric analysis. Sequence analysis reveals that thymosin beta 12 is 79% homologous to thymosin beta 4, an immunomodulator which was originally isolated from calf thymus. Thymosin beta 12 also shows 84% sequence homology to thymosin beta 11, a beta 4 analog which replaces beta 4 in two species of bony fish, oscar and rainbow trout. The evolutionary implication of such results will be discussed. The isolation of a new beta 4-related peptide from perch liver which differs from beta 11 indicates that beta-thymosin peptides are widely distributed in lower vertebrate classes.
Subject(s)
Liver/chemistry , Thymosin/chemistry , Amino Acid Sequence , Amino Acids/analysis , Animals , Chromatography, High Pressure Liquid , Mass Spectrometry , Molecular Sequence Data , Peptide Fragments/chemistry , Perches , Sequence Alignment , Species Specificity , Thymosin/classificationABSTRACT
In order to obtain specific antibodies against thymosin beta 9 showing minimal cross-reactivity with the highly homologous peptide thymosin beta 4, the N-terminal fragment 1-14 of thymosin beta 9 was used for immunization. These antibodies have been tested in a competitive ELISA and show less than 1% cross-reactivity with thymosin beta 4. On the other hand, antibodies raised against the native thymosin beta 9 (1-14) cross-react 35% with thymosin beta 4. Specific antibodies against thymosin beta 9 are important for studying the concentration and localization of thymosin beta 9 in thymus and other bovine tissues because thymosin beta 9 is always accompanied by thymosin beta 4. Using N-terminal fragments of thymosin beta 4-like peptides may be a general approach for obtaining specific antibodies since this part of sequence is less conserved in thymosin beta 4-like peptides.
Subject(s)
Thymosin/analysis , Amino Acid Sequence , Animals , Cattle , Chromatography, High Pressure Liquid , Cross Reactions , Molecular Sequence Data , Peptide Fragments/immunology , Thymosin/analogs & derivatives , Thymosin/blood , Thymosin/classification , Thymosin/immunology , Thymus Gland/analysisABSTRACT
Using a partially purified preparation, thymosin fraction 5, we have documented that thymosin can correct many of the immunological deficiencies resulting from the lack of thymosin function in animal models and in humans. Ongoing studies indicate that there is a family of biologically active peptides within fraction 5 that act on T-cell subpopulations to maintain normal immunological reactivity. Several of these peptides have been purified to homogeneity. Two peptides, thymosin alpha 1 and beta 4, have been sequenced and chemically synthesized. Thymosin fraction 5 has been used in most clinical trials reported to date, including children with immunodeficiency disease and patients with autoimmune diseases and cancer. Most recently, the National Cancer Institute has initiated a number of Phase I and Phase II clinical trials with thymosin fraction 5 and synthetic alpha 1 as part of a new Biological Response Modifier Program. Preliminary results from two of these studies look encouraging.
