SHLP2 Research & Studies

The online version contains supplementary material available at https://doi.org/10.1007/s10616-026-01070-z.

Allergic asthma (AA) is a lung disease characterized by impaired respiratory function and significant infiltration of inflammatory cells. Human Protein-Mimicking Peptide-2 (SHLP2) is a recently discovered mitochondria-encoded peptide that plays a crucial role in mitochondrial retrograde signaling pathways. However, its potential utility in mitigating AA remains unexplored. Our study investigates the therapeutic potential of SHLP2 in AA.

This study aimed to evaluate the cytoprotective effects of the mitochondrial-derived peptide, Small Humanin-Like Peptide-2 (SHLP2), on pre-osteoblastic cells exposed to sub-toxic oxidative stress, with the aim of preserving bone homeostasis under conditions of inflammaging. Pre-osteoblastic MC3T3-E1 cells were cultured under sub-toxic oxidative stress induced by 600 µM H2O2. The study evaluated the effects of SHLP2 (at 10 µM concentration) through assays for mitochondrial activity, reactive oxygen species (ROS) generation, apoptosis markers, and osteogenic differentiation. Quantitative polymerase chain reaction, alkaline phosphatase (ALP) staining, and Alizarin Red S biomineralization assays were performed to assess gene expression, osteogenic activity, and biomineralization. Oxidatively stressed but untreated cells served as the positive control (PC), while oxidative stress-free cells were used as the mock control. Statistical analyses were performed using one-way ANOVA and t-tests. SHLP2 treatment significantly (p < 0.001) improved cell viability and reduced ROS activity in oxidatively stressed cells. A significant (p < 0.001) decrease in apoptotic markers, including p53 and BAX, and an increase in anti-apoptotic BCL-2 levels, were observed. Additionally, SHLP2 treatment upregulated key osteogenic markers, including RUNX2, OSX, and ALP, compared to PC. When compared to the mock group, SHLP2 restored ALP activity to 95.6% by day 14. By day 21, the biomineralization assay demonstrated 94.92% activity following SHLP2 treatment. SHLP2 treatment effectively mitigates oxidative stress in pre-osteoblastic cells, providing apoptosis protection and preserving osteogenic activity. These findings underscore the potential of SHLP2 as an adjuvant therapeutic agent for enhancing the tissue microenvironment in conditions such as periodontitis and inflammaging.

Mitochondrial DNA single nucleotide polymorphisms (mtSNPs) have been associated with a reduced risk of developing Parkinson's disease (PD), yet the underlying mechanisms remain elusive. In this study, we investigate the functional role of a PD-associated mtSNP that impacts the mitochondrial-derived peptide (MDP) Small Humanin-like Peptide 2 (SHLP2). We identify m.2158 T > C, a mtSNP associated with reduced PD risk, within the small open reading frame encoding SHLP2. This mtSNP results in an alternative form of SHLP2 (lysine 4 replaced with arginine; K4R). Using targeted mass spectrometry, we detect specific tryptic fragments of SHLP2 in neuronal cells and demonstrate its binding to mitochondrial complex 1. Notably, we observe that the K4R variant, associated with reduced PD risk, exhibits increased stability compared to WT SHLP2. Additionally, both WT and K4R SHLP2 show enhanced protection against mitochondrial dysfunction in in vitro experiments and confer protection against a PD-inducing toxin, a mitochondrial complex 1 inhibitor, in a mouse model. This study sheds light on the functional consequences of the m.2158 T > C mtSNP on SHLP2 and provides insights into the potential mechanisms by which this mtSNP may reduce the risk of PD.

Small humanin-like peptide 2 (SHLP2) is a mitochondrial-derived peptide implicated in several biological processes such as aging and oxidative stress. However, its functional role in the regulation of energy homeostasis remains unclear, and its corresponding receptor is not identified. Hereby, we demonstrate that both systemic and intracerebroventricular (ICV) administrations of SHLP2 protected the male mice from high-fat diet (HFD)-induced obesity and improved insulin sensitivity. In addition, the activation of pro-opiomelanocortin (POMC) neurons by SHLP2 in the arcuate nucleus of the hypothalamus (ARC) is involved in the suppression of food intake and the promotion of thermogenesis. Through high-throughput structural complementation screening, we discovered that SHLP2 binds to and activates chemokine receptor 7 (CXCR7). Taken together, our study not only reveals the therapeutic potential of SHLP2 in metabolic disorders but also provides important mechanistic insights into how it exerts its effects on energy homeostasis.

Mitochondrial-derived peptides (MDPs) are rapidly emerging therapeutic targets to combat development of neurodegenerative diseases. SHLP2 (small humanin-like peptide 2) is a newly discovered MDP that is coded from the MT-RNR2 (Mitochondrially encoded 16S rRNA) gene in mitochondrial DNA (mtDNA). In the current study, we examined the biological consequences of treatment with exogenously-added SHLP2 in an in vitro human transmitochondrial age-related macular degeneration (AMD) ARPE-19 cell model. In AMD cells, we observed significant down-regulation of the MDP-coding MT-RNR2 gene, and remarkably reduced levels of all five oxidative phosphorylation (OXPHOS) complex I-V protein subunits that are involved in the electron transport chain; these results suggested mitochondrial toxicity and abnormal OXPHOS complex protein subunits' levels in AMD cells. However, treatment of AMD cells with SHLP2: (1) restored the normal levels of OXPHOS complex protein subunits, (2) prevented loss of viable cells and mitochondria, (3) increased the number of mtDNA copies, (4) induced anti-apoptotic effects, and (5) attenuated amyloid-β-induced cellular and mitochondrial toxicity. Cumulatively, our findings established the protective role of SHLP2 in AMD cells in vitro. In conclusion, this novel study supports the merit of SHLP2 in the treatment of AMD, a primary retinal disease that is a leading cause of blindness among the elderly population in the United States as well as worldwide.

Mitochondrial DNA mutations and dysfunction are associated with prostate cancer (PCa). Small humanin-like peptide-2 (SHLP2) is a novel mitochondrial-encoded peptide and an important mitochondrial retrograde signaling molecule.