Evidence for the extranuclear localization of thymosins in thymus

Abstract

A new radioimmunoassay has been developed for thymosin beta 4 by generating rabbit polyclonal antibodies against the synthetic N-terminal peptide fragment 1-15 coupled to KLH. The synthetic analogue [Tyr12]-thymosin beta 4 (1-15) was used as tracer. This radioimmunoassay, with a useful range of 10-1000 pmoles, showed cross-reactivity with the second homologous beta-thymosin of man and rat (thymosin beta 10) but not of calf (thymosin beta 9). This radioimmunoassay, together with an improved radioimmunoassay for the N-terminus of parathymosin alpha, was employed for the measurement of the levels of thymosin beta 4 and parathymosin alpha in nuclear and extranuclear extracts of calf thymus. The bulk of these polypeptides was found in the extranuclear material whereas only traces were observed in the nuclear environment, which indicates the extranuclear localisation of alpha- and beta-thymosins.

Nuclear Localization of Parathymosin in Rat and Human Hepatocytes. A Light and Ultrastructural study.

“…On the other hand, Tsitsiloni et al (21) found an extranuclear localization of ParaT in thymus by radioimmunoassay and we have previously reported, by light immunohistochemical procedures, the cytoplasmic localization of ParaT in the reticuloepithelial cells of the rat thymus (16). Similarly, Brand et al (2) found immunostaining for ParaT exclusively in the cytoplasm of most cell types that they studied, including hepatocytes.…”

“…However, the main physiological function of ParaT has not been found (2). Its intracellular localization is also controversial and both a nuclear (2,6,22) and a cytoplasmic distribution (3,16,21) have been proposed. The aim of the present work was to determine, by light immunohistochemical and immunogold labelling procedures, the subcellular distribution of ParaT in rat and human hepatocytes.…”

Advances in Thymosin β10 Research: Differential Expression, Molecular Mechanisms, and Clinical Implications in Cancer and Other Conditions

“…β-Thymosins contain highly conserved acidic 5 kDa peptides consisting of 40-44 amino acid residues, of which 50% are charged (4,5). To date, there are at least 15 β-thymosins identified in species ranging from various invertebrates to vertebrates (2,6), and they are thought to be localized in either the nucleus or cytoplasm (7,8) and can interact with monomeric G-actins (9)(10)(11). The first β-thymosin peptide isolated was thymosin β1 (Tβ1) (12).…”

A novel β-thymosin from the sea urchin: extending the phylogenetic distribution of β-thymosins from mammals to echinoderms

“…During the past few years it has been found that their distribution is not limited to the thymus but that they are also present in numerous tissues [5,6]. Recent experiments provided evidence for their extranuclear localization in the cells [7]. Different b-thymosin peptides have been isolated from many species of the animal kingdom, ranging from amphibia to mammals [8±15].…”