What is SHLP-2?
The problem: mitochondrial biology is more complex than an “energy factory”
Mitochondria are often described as the cell’s power stations. That analogy is useful, but incomplete. A modern power station also sends signals, responds to faults and helps coordinate the wider electricity grid.
Mitochondria do something similar. They produce energy, regulate stress responses and communicate with the rest of the cell. They also contain their own small circular genome, known as mitochondrial DNA, or mtDNA.
Researchers discovered that mtDNA contains short open reading frames. Small genetic sections capable of producing tiny proteins or peptides. These are called mitochondria-derived peptides, or MDPs.
SHLP-2 is one of six small humanin-like peptides, named SHLP-1 through SHLP-6. The family is encoded within the 16S ribosomal RNA region of mitochondrial DNA.
The research opportunity: a small peptide with system-wide signals
SHLP-2 is a short peptide, but its proposed actions reach beyond the mitochondria. Research has examined whether it can influence:
- Cell survival and apoptosis, the programmed removal of damaged cells
- Reactive oxygen species, or ROS, which are chemically reactive molecules produced during metabolism
- Mitochondrial metabolism and oxidative phosphorylation
- Insulin signalling and glucose disposal
- Hypothalamic control of appetite and energy expenditure
- Amyloid-related cellular stress
- Age-associated changes in circulating mitochondrial peptides
Think of SHLP-2 as a possible message sent from the cell’s power station to the rest of the biological “building”. The message may say: reduce unnecessary damage, improve fuel handling and adapt to stress.
The important word is possible. These mechanisms are still being tested.
Why has SHLP-2 received the most attention of the six SHLPs?
The problem: the six SHLPs are often grouped together
Because SHLP-1 through SHLP-6 share a family name, it is easy to assume they have identical effects. They do not.
Each peptide has its own sequence, structure and biological activity. Some have received limited investigation, while SHLP-2 has been examined across several connected research areas.
The solution: follow the strongest evidence base
SHLP-2 has drawn the most attention because researchers have identified several lines of evidence:
- Cell studies have examined mitochondrial protection, oxidative stress and amyloid-related toxicity.
- Retinal research has investigated SHLP-2 in models relevant to age-related macular degeneration.
- Animal studies have reported effects on insulin sensitivity, glucose tolerance, appetite and thermogenesis.
- Human observational studies have measured circulating SHLP-2 in relation to age, obesity and diabetes.
- Mechanistic work has proposed a receptor pathway involving CXCR7 and ERK signalling in mouse models.
A 2023 Nature Communications study was particularly influential because it linked SHLP-2 to hypothalamic neurons involved in energy balance. In male mice, systemic and intracerebroventricular administration was associated with lower food intake, increased thermogenesis and improved insulin sensitivity.
That does not prove the same results occur in humans. It does explain why SHLP-2 currently stands out among the six SHLPs.
Short version: SHLP-2 has the broadest and most connected preclinical research profile in the SHLP family.