Rat Humanin, Nuclear-encoded/HN(N) ELISA Kit

Humanin is a small regulatory peptide encoded within the 16S ribosomal RNA gene (MT-RNR2) of the mitochondrial genome that has cellular cyto- and metabolo-protective properties similar to that of aerobic exercise training. Here we investigated whether acute high-intensity interval exercise or short-term high-intensity interval training (HIIT) impacted skeletal muscle and plasma humanin levels. Vastus lateralis muscle biopsies and plasma samples were collected from young healthy untrained men (n = 10, 24.5 +/- 3.7 yr) before, immediately following, and 4 h following the completion of 10 x 60 s cycle ergometer bouts at Vo(2peak) power output (untrained). Resting and postexercise sampling was also performed after six HIIT sessions (trained) completed over 2 wk. Humanin protein abundance in muscle and plasma were increased following an acute high-intensity exercise bout. HIIT trended (P = 0.063) to lower absolute humanin plasma levels, without effecting the response in muscle or plasma to acute exercise. A similar response in the plasma was observed for the small humanin-like peptide 6 (SHLP6), but not SHLP2, indicating selective regulation of peptides encoded by MT-RNR2 gene. There was a weak positive correlation between muscle and plasma humanin levels, and contraction of isolated mouse EDL muscle increased humanin levels similar to 4-fold. The increase in muscle humanin levels with acute exercise was not associated with MT-RNR2 mRNA or hunzanin mRNA levels (which decreased following acute exercise). Overall, these results suggest that humanin is an exercise-sensitive mitochondrial peptide and acute exercise-induced humanin responses in muscle are nontranscriptionally regulated and may partially contribute to the observed increase in plasma concentrations. NEW & NOTEWORTHY Small regulatory peptides encoded within the mitochondrial genome (mitochondrial derived peptides) have been shown to have cellular cyto- and metabolo-protective roles that parallel those of exercise. Here we provide evidence that humanin and SHLP6 are exercise-sensitive mitochondrial derived peptides. Studies to determine whether mitochondrial derived peptides play a role in regulating exercise-induced adaptations are warranted.

The NMR solution study of Ser14Gly-humanin (S14G-HN), a 1000-fold more potent derivative of humanin (HN), is reported. HN is 24-residue peptide that selectively suppresses neuronal cell death caused by Alzheimer's disease (AD)-specific insults and offers hope for the development of a cure against AD. In aqueous solution the NMR data show that S14G-HN is a flexible peptide with turn-like structures in its conformational ensemble distributed over an extensive part of its sequence from Pro3 to Glu15. In the more lipophilic environment of 30% TFE, an alpha-helical structure spanning residues Phe6 to Thr13 is identified. Comparison of these findings to the NMR structure of the parent HN and to existing structure-function relationship literature data outlines the important for activity structural features for this class of neuroprotective peptides, and brings forth flexibility as an important characteristic that may facilitate interactions with functional counterparts of the neuroprotection pathway. (c) 2006 Elsevier Inc. All rights reserved.