Thymosin beta 4 and its N-terminal tetrapeptide, AcSDKP, inhibit proliferation, and induce dysplastic, non-apoptotic nuclei and degranulation of mast cells.
Leeanansaksiri. Wilairat W; DeSimone. Shirley K SK; Huff. Thomas T; Hannappel. Ewald E; Huff. Thomas F TF
Key Findings
- Both thymosin beta‑4 and AcSDKP inhibit mast‑cell proliferation across a wide concentration range, with peak effect at 10⁻¹⁴ M.
- Treated mast cells develop abnormal, fragmented nuclei and arrest in the G2 phase of the cell cycle.
- At 10⁻⁸ M, the peptides trigger mast‑cell degranulation (57% for Tβ4, 89% for AcSDKP), while smaller fragments are inactive.
Practical Outcomes
- These results hint that ultra‑low doses of Tβ4 or AcSDKP might dampen mast‑cell driven inflammation, but doses that are too high could provoke degranulation and potentially worsen inflammatory responses. For biohackers, there is no clear, safe dosing protocol yet, and more human‑focused research is needed before practical use.
Summary
The study shows that the protein thymosin beta‑4 and its short piece AcSDKP can stop mast cells from multiplying and push them into a growth‑stop state at extremely low concentrations, but higher doses make the cells release their stored chemicals. Only the whole peptide and the four‑amino‑acid piece work; broken‑down fragments do not.
Abstract
Thymosin beta4 (Tbeta4), a 5 kDa polypeptide, is a member of the beta-thymosin family. It acts as the principal intracellular G-actin sequestering peptide and exhibits extracellular functions in angiogenesis and wound healing. The N-terminus of Tbeta4 contains a bioactive tetrapeptide, acSDKP, a negative regulator of hematopoietic stem-cell proliferation. Here, we show that both peptides inhibit mast-cell proliferation over the concentration range of 10(-6) to 10(-17) M with the maximum effect of both at 10(-14) M. Both Tbeta4 and acSDKP caused dysplastic mast-cell nuclei that were confirmed by DAPI fluorescent staining. Flow-cytometric analysis of ploidy revealed that the dysplastic nuclei were not multinucleated, but fragmented nuclei in G2 growth arrest. We could further demonstrate that 10(-8) or 10(-14) M Tbeta4 or acSDKP induce mast-cell degranulation. A concentration of 10(-8) M Tbeta4 or acSDKP caused 57 or 89% degranulation, respectively. A number of tryptic fragments of Tbeta4 were assayed beside intact Tbeta4 and the tetrapeptide, and found to be inactive.
Study Information
pubmed
2004
10.1002/cbdv.200490081