Two serine residues distinctly regulate the rescue function of Humanin, an inhibiting factor of Alzheimer's disease-related neurotoxicity: functional potentiation by isomerization and dimerization.
Terashita. Kenzo K; Hashimoto. Yuichi Y; Niikura. Takako T; Tajima. Hirohisa H; Yamagishi. Yohichi Y; Ishizaka. Miho M; Kawasumi. Masaoki M; Chiba. Tomohiro T; Kanekura. Kohsuke K; Yamada. Marina M; Nawa. Mikiro M; Kita. Yoshiko Y; Aiso. Sadakazu S; Nishimoto. Ikuo I
Key Findings
- D‑Serine at position 14 makes Humanin 100‑1000× more potent
- Serine at position 7 is required for Humanin to dimerize, a step needed for neuroprotection
- A dimeric Humanin variant with D‑Ser14 is fully protective at 10 pM against toxic Aβ peptide
Practical Outcomes
- For biohackers, the study highlights that modifying Humanin to include D‑Ser14 and encouraging dimer formation could yield a far more powerful anti‑Alzheimer agent. However, these findings are still at the cell‑culture stage, so no concrete dosing or supplement recommendations exist yet. Future work may lead to ultra‑low‑dose Humanin analogs for longevity or brain health, but they are not currently available for self‑experimentation.
Summary
Scientists found that tiny changes to the 24‑amino‑acid peptide Humanin make it dramatically better at protecting brain cells from Alzheimer‑related damage. Swapping the natural Serine at position 14 for its mirror‑image form (D‑Ser) boosts its protective power by 100‑ to 1,000‑fold, while the Serine at position 7 is needed for the peptide to pair up (dimerize), which is also essential for its effect. The most potent version worked at picomolar levels in lab tests, suggesting a path to ultra‑effective Humanin‑based therapies, though it’s still far from a usable supplement or drug.
Abstract
The 24-residue peptide Humanin (HN), containing two Ser residues at positions 7 and 14, protects neuronal cells from insults of various Alzheimer's disease (AD) genes and A beta. It was not known why the rescue function of (S14G)HN is more potent than HN by two to three orders of magnitude. Investigating the possibility that the post-translational modification of Ser14 might play a role, we found that HN with D-Ser at position 14 exerts neuroprotection more potently than HN by two to three orders of magnitude, whereas D-Ser7 substitution does not affect the rescue function of HN. On the other hand, S7A substitution nullified the HN function. Multiple series of experiments indicated that Ser7 is necessary for self-dimerization of HN, which is essential for neuroprotection by this factor. These findings indicate that the rescue function of HN is quantitatively modulated by d-isomerization of Ser14 and Ser7-relevant dimerization, allowing for the construction of a very potent HN derivative that was fully neuroprotective at 10 pM against 25 microM A beta1-43. This study provides important clues to the understanding of the neuroprotective mechanism of HN, as well as to the development of novel AD therapeutics.
Study Information
pubmed
2003
2003-05-13T00:00:00.000Z
10.1046/j.1471-4159.2003.01797.x
66
42