Klotho
| Category | Compounds |
|---|---|
| Also known as | α-Klotho, Alpha-Klotho |
| Last updated | 2026-04-14 |
| Reading time | 3 min read |
| Tags | longevityanti-aginghormonecognitionresearch |
Overview
Klotho (α-Klotho) was originally identified in mice where loss of function caused a syndrome resembling accelerated aging, and where overexpression extended lifespan. It exists as a membrane protein highly expressed in kidney, parathyroid, and choroid plexus, and as a circulating soluble form produced by ectodomain shedding. The soluble form acts as an endocrine factor with pleiotropic effects on phosphate homeostasis, insulin and IGF-1 signaling, vascular biology, and cognition.
Klotho is tightly linked to FGF21 biology because the related β-Klotho is the obligate co-receptor for FGF21 and FGF19. α-Klotho likewise serves as a co-receptor for FGF23 in the bone-kidney axis. Human observational studies associate lower circulating klotho with higher mortality, cardiovascular risk, and cognitive decline, which is why it attracts attention from longevity researchers alongside peptides like Epitalon, MOTS-c, and Humanin.
Exogenous klotho is a research compound rather than a registered therapeutic. Studies use recombinant klotho protein or viral delivery in animal models. It is frequently discussed in the context of peripheral administration and cognitive endpoints based on mouse studies showing cognitive enhancement after peripheral klotho injections.
Structure / Chemistry
Klotho is a large type-I single-pass transmembrane glycoprotein with tandem β-glucosidase-like KL1 and KL2 domains. Ectodomain shedding by ADAM10/17 releases a ~130 kDa soluble form into circulation. Research klotho reagents are typically recombinant full-length ectodomain or KL1-only variants.
Mechanism of Action
Membrane klotho complexes with FGFR1 to confer high-affinity binding for FGF23, which regulates phosphate and vitamin D metabolism. Soluble klotho acts on multiple pathways including inhibition of IGF-1/insulin signaling, modulation of Wnt activity, regulation of TRPV5 calcium channels, and effects on oxidative stress and NMDA receptor function in the brain. These pathways collectively influence aging-related phenotypes.
Research Summary
| Area | Finding | Reference |
|---|---|---|
| Discovery | Klotho mutation caused premature aging in mice | Kuro-o et al., Nature 1997 |
| Longevity | Klotho overexpression extended mouse lifespan | Kurosu et al., Science 2005 |
| Cognition | Peripheral klotho enhanced cognition in mice | Leon et al., Cell Reports 2017 |
| Cognition (primate) | Low-dose klotho improved cognition in aged macaques | Castner et al., Nat Aging 2023 |
| Human epidemiology | Low klotho linked to cardiovascular/mortality risk | Semba et al., J Gerontol 2011 |
Pharmacokinetics
Recombinant klotho in rodent studies has a reported plasma half-life on the order of minutes to hours, depending on the form used, though biological effects after single injections persist far longer than plasma levels would suggest. Administration in animal studies is intravenous or subcutaneous. Human pharmacokinetics are not well established.
Common Discussion Topics
- Rodent-to-primate translation of cognitive benefits.
- Distinction between α-Klotho (kidney/brain) and β-Klotho (liver) biology.
- Role in the FGF23-phosphate axis.
- Short plasma half-life vs. sustained cognitive effects.
- Overlap with longevity research on Epitalon and Rapamycin.
Related Compounds
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Related entries
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- FGF21— FGF21 is a liver-derived metabolic hormone of the fibroblast growth factor family that regulates energy balance, glucose handling, and macronutrient preference.
- Humanin— A 24-amino-acid mitochondrial-derived peptide encoded within the 16S ribosomal RNA gene of mitochondrial DNA, the first MDP discovered, studied extensively for its neuroprotective, anti-apoptotic, and cytoprotective properties across multiple organ systems.
- MOTS-c— A 16-amino-acid mitochondrial-derived peptide encoded within the 12S rRNA gene of mitochondrial DNA, identified as an exercise mimetic that activates AMPK signaling and regulates metabolic homeostasis.
- NAD+ Precursors— Compounds that elevate cellular NAD+ levels, including NMN and NR, studied for their roles in sirtuin activation, mitochondrial function, and aging biology.