Klotho (Alpha-Klotho)

The Longevity Protein and Its Engineered Long-Acting Form

Aging is not the product of a single failing pathway. It is the gradual breakdown of coordination between cellular energy production, vascular signaling, mineral balance, and stress-response systems. Few molecules sit upstream of all these processes simultaneously—α-Klotho is one of them. α-Klotho is a naturally occurring transmembrane and circulating protein whose levels decline steadily with age. First identified in 1997 by Kuro-o and colleagues, it was named after Klotho, the Greek mythological figure who spins the thread of life—an apt metaphor for a protein that appears to regulate biological longevity at a systems level. Lower circulating α-Klotho concentrations are consistently associated with reduced muscle strength, vascular stiffness, kidney dysfunction, cognitive decline, and impaired metabolic flexibility. Conversely, higher α-Klotho levels correlate with improved physical performance, healthier endothelial function, and greater resistance to age-related decline. These associations have placed α-Klotho at the forefront of modern longevity research. However, native soluble α-Klotho has a significant limitation: its half-life in circulation is short, restricting its ability to maintain stable physiological signaling. alphaKlothoLR (Long-Range) was engineered specifically to address this constraint. By incorporating a proprietary albumin- binding domain (protected under US Patent 12,377,158), alphaKlothoLR associates with serum albumin—which has a half-life of approximately 19 days in humans—dramatically extending systemic exposure while preserving native biological activity. This article provides a comprehensive review of α-Klotho biology, the scientific rationale for alphaKlothoLR, current research findings, suggested research protocols, safety considerations, and practical guidance for investigators.

How It Works

α-Klotho as a Systems-Level Regulator Unlike compounds that target a single receptor or symptom, α-Klotho operates at a systems level. It influences multiple organs simultaneously, including skeletal muscle, brain, cardiovascular tissue, kidneys, lungs, and the vascular endothelium. This breadth of action is why α-Klotho is described as a longevity regulator rather than a performance enhancer or acute recovery agent. α-Klotho exists in two primary forms:

• Membrane-bound α-Klotho: Functions as a co-receptor for fibroblast growth factor 23

(FGF23), primarily expressed in the kidneys, parathyroid glands, and choroid plexus.

• Soluble α-Klotho (sKL): A shed or secreted form that circulates systemically and acts

on multiple organ systems through FGF23-independent mechanisms.

FGF23 Interaction and Mineral Metabolism

One of α-Klotho’s best-characterized roles is its function as an obligate co-receptor for FGF23 in the regulation of phosphate and vitamin D homeostasis. The membrane-bound form of α-Klotho complexes with FGFR1c to create a high-affinity receptor for FGF23, enabling:

• Urinary phosphate excretion (phosphaturia)
• Suppression of renal 1-alpha-hydroxylase, limiting 1,25-dihydroxyvitamin D synthesis
• Parathyroid hormone (PTH) regulation

Disruption of the FGF23-Klotho axis leads to hyperphosphatemia, ectopic calcification, and accelerated vascular aging—phenotypes that closely resemble premature aging syndromes observed in Klotho-deficient animals.

Mitochondrial Biogenesis and Cellular Energy

One of the most important—and often underappreciated—aspects of α-Klotho biology involves mitochondrial density and function. Many interventions attempt to make existing mitochondria work harder or more efficiently. α-Klotho, by contrast, is associated with the maintenance of mitochondrial density and has been shown to support mitochondrial biogenesis in preclinical models. This distinction matters because high-energy tissues such as skeletal muscle, the brain, and the cardiovascular system depend on both mitochondrial quality and quantity. As mitochondrial density declines with age, cells experience energy shortfalls even when individual mitochondria remain functional. Research by Sahu et al. (2018) demonstrated that age-related declines in α- Klotho impair progenitor cell mitochondrial function and muscle regeneration—a finding with profound implications for sarcopenia and musculoskeletal aging.

Vascular Function and Endothelial Resilience

α-Klotho plays a significant role in vascular health through its interaction with endothelial nitric oxide (NO) signaling. Adequate NO production is essential for vascular elasticity, proper blood flow regulation, oxygen and nutrient delivery, and protection against vascular calcification. Declining α-Klotho levels are associated with increased vascular stiffness and impaired endothelial responsiveness. Maintaining physiological α-Klotho signaling supports vascular adaptability, which is critical for long-term cardiovascular and metabolic health.

Oxidative Stress, Nrf2 Activation, and FoxO Modulation

α-Klotho activates antioxidant defense pathways, including Nrf2-mediated gene expression, and modulates FoxO transcription factors involved in cellular stress resistance. Through these mechanisms, α-Klotho reduces oxidative damage at the cellular and mitochondrial level. Yamamoto et al. (2005) demonstrated that Klotho regulates oxidative stress through suppression of insulin and IGF-1 signaling, activating FoxO-dependent antioxidant genes. Maltese et al. (2016) confirmed that Klotho induces Nrf2-mediated antioxidant defenses in human aortic smooth muscle cells.

Inflammation and Fibrosis Modulation

α-Klotho interacts with pathways that regulate chronic inflammation and fibrosis, including NF- κB, Wnt, and TGF-β signaling. This positions α-Klotho as a stabilizing influence across tissues prone to age-related inflammatory and fibrotic remodeling, such as the kidneys, vasculature, lungs, and liver. Zhao et al. (2024) provided a comprehensive molecular and cellular analysis of Klotho’s roles in suppressing both inflammatory and fibrotic cascades.

Neurological and Synaptic Function

α-Klotho is expressed in brain tissue, particularly the choroid plexus and hippocampal regions, and influences synaptic function, neuronal energy metabolism, and resistance to neurotoxic stress. Research links higher α-Klotho levels with improved cognitive performance, synaptic plasticity, and protection against oxidative and inflammatory damage in neural tissue. Rather than acting as a stimulant or direct neuromodulator, α-Klotho supports the underlying cellular environment required for durable cognitive function over time.

alphaKlothoLR: Technical Design and Albumin-Binding Mechanism Native soluble α-Klotho has a relatively short half-life in circulation—estimated at several hours—limiting its ability to maintain stable physiological signaling. alphaKlothoLR was engineered with a proprietary albumin-binding domain to potentially extend systemic exposure through association with serum albumin (half-life approximately 19 days in humans). The albumin-binding construct consists of the amino acid sequence:

GGSGGSGGSGGRLIEDICLPRWGCLWEDD

This construct incorporates:

• An 11-amino acid glycine-serine flexible linker (GGSGGSGGSGG): Providing

hydrophilicity and conformational flexibility.

• The core SA21 peptide (RLIEDICLPRWGCLWEDD): Containing the

DICLPRWGCLW albumin-binding sequence with a combined KD of less than 20 nM to human albumin.

• Preserved FGF23 binding affinity: KD of 16.2 nM compared to 15–30 nM for native

Klotho.

The construct is produced through recombinant expression in mammalian cell systems (CHO, HEK293) or transgenic insect cells, preserving proper protein folding and glycosylation patterns critical for biological activity. Albumin-binding has been confirmed across multiple species, including human and canine, with similar high-affinity characteristics.

Research Benefits

Musculoskeletal Health and Physical Performance

Circulating α-Klotho levels correlate strongly with physical performance markers. Semba et al. (2011) demonstrated in the InCHIANTI study that low plasma Klotho is associated with poor grip strength in older community-dwelling adults. Arroyo et al. (2022) reviewed Klotho’s ergogenic potential, noting its associations with muscle function, exercise capacity, and resistance to physical decline. Clemens et al. (2021) found that the impact of Klotho on skeletal muscle function is biphasic and age-dependent, underscoring the importance of context in interpreting Klotho’s effects.

Cardiovascular and Vascular Protection

α-Klotho’s role in endothelial function and vascular calcification prevention is well-supported in the literature. Its regulation of mineral metabolism through FGF23 prevents ectopic vascular calcification associated with hyperphosphatemia. Additionally, Klotho’s enhancement of nitric oxide signaling and its modulation of PI3K/Akt pathways—demonstrated by Hung et al. (2020) in pulmonary vein cardiomyocytes—support broader cardiovascular protective effects.

Renal Preservation

The kidneys are both the primary source of circulating α-Klotho and a primary target of its protective actions. Kale et al. (2021) described Klotho’s role in kidney diseases through its crosstalk with the renin-angiotensin system and endoplasmic reticulum stress pathways. Donate- Correa et al. (2023) reviewed Klotho’s mitochondrial protective effects in kidney disease. Hu et al. (2015) examined Klotho’s influence on stem cell biology and renal aging. Zhou et al. (2023) demonstrated that Klotho activates Nrf2 to inhibit ferroptosis signaling in sepsis-associated acute kidney injury.

Cognitive Function and Neuroprotection

Higher α-Klotho levels are associated with preserved cognitive function across aging populations. Mytych (2021) reviewed the mutual crosstalk between Klotho, autophagy, endoplasmic reticulum stress, and neuroinflammation. Orellana et al. (2023) demonstrated that Klotho increases antioxidant defenses in astrocytes and ubiquitin-proteasome activity in

neurons—mechanisms directly relevant to neurodegenerative disease resistance.

Metabolic Regulation

Klotho influences metabolic pathways through both central and peripheral mechanisms. Landry et al. (2021) demonstrated that circulating α-Klotho regulates metabolism via distinct central and peripheral actions. Lin and Sun (2012) found that Klotho enhances glucose-induced insulin secretion by upregulating TRPV2 plasma membrane expression in beta cells, though the in vivo metabolic role of Klotho independent of vitamin D remains an area of active investigation (Anour et al., 2012).

Pulmonary and Multi-Organ Protection

Kim et al. (2017) demonstrated that Klotho attenuates oxidant-induced alveolar epithelial cell mitochondrial DNA damage and apoptosis, extending its protective effects to lung tissue. Al- Kadi et al. (2025) identified Klotho as a multifaceted protector against sepsis-induced organ damage, suggesting translational potential beyond the classical aging context.

What the Science Shows

Key Preclinical Findings

The Klotho-deficient mouse model remains the foundational tool for understanding α-Klotho biology. These animals exhibit a dramatically accelerated aging syndrome characterized by hyperphosphatemia, vascular calcification, muscle atrophy, skin atrophy, osteopenia, cognitive impairment, and shortened lifespan. Conversely, Klotho-overexpressing mice display extended lifespan, improved physical performance, and resistance to oxidative stress—establishing a direct causal link between α-Klotho levels and biological aging rate.

Key Clinical and Epidemiological Evidence

The most comprehensive human data on α-Klotho comes from epidemiological cohort studies. The InCHIANTI study (Semba et al., 2011) found that older adults in the lowest quartile of plasma Klotho had significantly lower grip strength and poorer physical performance compared to those in higher quartiles—an association that remained significant after controlling for confounders including vitamin D, PTH, and kidney function. Population-level data consistently show that α-Klotho levels peak in early adulthood and decline progressively with age, with accelerated declines observed in the setting of chronic kidney disease, diabetes, and cardiovascular disease.

Albumin-Binding Technology: alphaKlothoLR

The engineering of alphaKlothoLR represents a significant methodological advance for research involving exogenous Klotho administration. The SA21 albumin-binding peptide has been extensively characterized, demonstrating binding to human serum albumin with a KD of 7.94 nM while maintaining Klotho’s native FGF23 binding affinity at 16.2 nM—comparable to the 15–30 nM range reported for wild-type Klotho. Unlike many hormone-replacement strategies that suppress endogenous production through negative feedback, the impact of exogenous Klotho administration on endogenous expression remains under investigation. Theoretical considerations suggest that Klotho, as a circulating protein rather than a classical hormone, may not follow typical feedback suppression patterns— though long-term clinical data are needed to confirm this hypothesis.

Summary Evidence Table

Study / Author Model Key Finding Kuro-o et al., Mouse (KO model) Klotho-deficient mice display premature aging 1997 phenotype; overexpression extends lifespan Semba et al., Human Low plasma Klotho associated with reduced grip 2011 (InCHIANTI strength in older adults cohort) Sahu et al., 2018 Mouse α-Klotho decline impairs progenitor cell mitochondrial function and muscle regeneration Yamamoto et In vitro / Mouse Klotho regulates oxidative stress via FoxO- al., 2005 dependent antioxidant pathways Maltese et al., Human cell line Klotho induces Nrf2-mediated antioxidant defenses 2016 in aortic smooth muscle cells Zhao et al., Review Comprehensive molecular analysis of Klotho in 2024 inflammation and fibrosis suppression Landry et al., Mouse Circulating α-Klotho regulates metabolism through 2021 central and peripheral mechanisms Clemens et al., Mouse Klotho’s impact on skeletal muscle function is 2021 biphasic and age-dependent Zhou et al., Mouse / Cell Klotho activates Nrf2 to inhibit ferroptosis in 2023 sepsis-associated acute kidney injury

Suggested Dosing Protocol

The following dosing information reflects current research literature and is intended strictly for research purposes. No clinical dosing guidelines for alphaKlothoLR in humans have been established. All dosing should be conducted under appropriate research oversight.

Standard Research Protocol

Parameter Details Form Lyophilized powder; reconstitute prior to use Typical Research Dose 2 mcg–1.0 mg per administration (subcutaneous)

Range

Frequency Once every 13 days, given extended half-life from albumin binding Research Duration 4–12 weeks observed in preclinical protocols Route Subcutaneous injection (SC)

Application-Specific Considerations

• Musculoskeletal / Physical Performance Research: Protocols in the 4–8 week range

have been used to assess effects on grip strength and muscle fiber composition markers.

• Vascular / Cardiovascular Research: Longer protocols (8–12 weeks) are preferred to

assess endothelial function and vascular compliance endpoints.

• Cognitive / Neurological Research: Chronic administration models are most

informative given the slow progression of neurological endpoints.

• Metabolic Research: Insulin secretion and glucose metabolism markers may be

assessable within shorter 4–6 week windows.

Reconstitution Guidelines

• Reconstitute lyophilized alphaKlothoLR with sterile bacteriostatic water or sterile saline.
• Add diluent slowly along the vial wall; do not inject directly onto the powder.
• Gently swirl—do not vortex or shake vigorously.
• Typical working concentration: 0.5–1.0 mg/mL.
• Allow to sit at room temperature for 5–10 minutes after reconstitution to ensure complete

dissolution.

• Inspect visually; solution should be clear and colorless. Do not use if particulate matter is

present.

• Reconstituted solution is stable for up to 28 days under refrigeration (2–8°C).

Side Effects

Common Injection-Site Reactions

As with any subcutaneous peptide, the most commonly observed adverse effects in preclinical models include transient injection-site reactions: mild erythema, swelling, or tenderness at the injection site. These are typically self-resolving and can be minimized by rotating injection sites and using appropriate injection technique.

Theoretical Considerations

• Mineral Metabolism Perturbation: Given α-Klotho’s role in FGF23 signaling and

phosphate regulation, exogenous administration could theoretically alter phosphate and vitamin D homeostasis. Monitoring serum phosphate and calcium in long-duration research protocols is advisable.

• Immune Response to Recombinant Protein: As with all recombinant proteins, there is

a theoretical risk of immunogenicity, particularly with repeated administration. Anti-drug antibody formation has not been specifically characterized for alphaKlothoLR.

• Cardiovascular Effects: α-Klotho modulates PI3K/Akt signaling in cardiac tissue (Hung

et al., 2020). While this is generally considered protective, the implications of exogenous administration at supraphysiological concentrations require further characterization.

• Suppression of Endogenous Production: The feedback dynamics of exogenous Klotho

administration on endogenous Klotho expression remain incompletely characterized. This distinguishes Klotho from classical hormones but does not eliminate the theoretical possibility of regulatory adaptation.

Clinical Trial Data

As of the time of writing, alphaKlothoLR is an investigational research construct without completed human clinical trials. Safety data are derived from preclinical models and in vitro characterization. Formal safety and toxicology studies in human populations have not been published. Investigators should adhere to all applicable institutional and regulatory guidelines.

Contraindications and Precautions

alphaKlothoLR is a research compound and is not approved for human therapeutic use. The following contraindications and precautions apply in the context of research use:

• Known hypersensitivity: Research subjects with known hypersensitivity to recombinant

proteins or albumin-binding peptides should be excluded from protocols.

• Active malignancy: α-Klotho has been identified as a tumor suppressor in certain cancer

contexts (e.g., breast, pancreatic, non-small cell lung cancer). However, its role in other malignancies is not fully characterized, and exogenous administration in the setting of active malignancy requires careful consideration.

• Chronic kidney disease (CKD): While α-Klotho loss is a hallmark of CKD and

supplementation has been proposed therapeutically, the altered FGF23-Klotho axis in CKD patients means that exogenous Klotho could produce unpredictable phosphate and mineral metabolism effects. Specialized monitoring is required.

• Pregnancy and lactation: No safety data exist. Exclude from research protocols

involving pregnant or lactating subjects.

• Concurrent FGF23-modulating therapies: Co-administration with drugs affecting

FGF23 or PTH signaling (e.g., burosumab, active vitamin D analogs) introduces potential for unpredictable mineral metabolism effects.

• Pediatric populations: No data. Exclude from pediatric research protocols.

Comparison: alphaKlothoLR vs. Related Longevity Compounds

Feature alphaKlothoLR NAD+ GH Peptides Rapamycin Precursors (CJC, Ipamorelin) (NMN/NR) Primary Systems regulator; NAD+ GH/IGF-1 axis mTOR Mechanism FGF23 co-receptor, repletion; stimulation inhibition mitochondrial, sirtuin vascular, neuro activation Half-Life Extended via Hours (NAD+ Hours to days Days albumin binding metabolite) (depending on (~days) form) Multi- Yes (renal, vascular, Partial Primarily Partial System neuro, muscle, lung) (mitochondrial anabolic/metabolic (autophagy, Activity focus) immunity) Endogenous Low (theoretical; Minimal Moderate (GH axis Yes Feedback not established) suppression) (immune, Risk metabolic) Clinical Preclinical + Phase II/III Extensive clinical Human trials Evidence epidemiological human trials use (transplant, Level aging) Specificity Pleiotropic Metabolic focus Growth/body Anti-aging longevity regulator composition via mTOR suppression

alphaKlothoLR’s primary distinction lies in its upstream regulatory position across multiple aging-sensitive pathways simultaneously, combined with its engineered pharmacokinetic profile that aligns with sustained physiological—rather than pulsatile—signaling.

Success Tips for Research Use

• Establish baseline biomarkers before initiating protocols: Serum phosphate, calcium,

FGF23, vitamin D (25-OH and 1,25-dihydroxy), parathyroid hormone, kidney function panel, and inflammatory markers (CRP, IL-6) provide the most informative baseline constellation for tracking α-Klotho-mediated changes.

• Consider the FGF23-Klotho axis holistically: Elevations in FGF23 without

corresponding Klotho activity are independently associated with cardiovascular risk. Monitoring both FGF23 and phosphate provides context for interpreting alphaKlothoLR’s biological effects.

• Use the extended half-life to design stable-exposure protocols: The albumin-binding

mechanism supports once- to twice-weekly administration schedules rather than daily dosing, which simplifies research logistics and reduces injection-site burden.

• Avoid supraphysiological dosing targets: The design philosophy of alphaKlothoLR is

physiological alignment rather than acute supraphysiological peaks. Protocols should aim to restore or maintain levels within the normal adult physiological range rather than to maximize peak concentration.

• Combine with functional outcome assessments: Given α-Klotho’s association with grip

strength, cognitive performance, and vascular function, incorporating standardized functional tests (e.g., handgrip dynamometry, six-minute walk test, cognitive assessments) alongside biochemical endpoints provides more comprehensive research data.

• Ensure cold-chain compliance: Protein stability is critical. Maintain cold-chain integrity

throughout shipping and storage, and verify reconstituted solution clarity before each use.

• Source only from verified, third-party-tested suppliers: Research-grade purity and

identity verification (HPLC, mass spectrometry) are essential for meaningful experimental results.

Storage and Handling

Condition Specification Lyophilized powder Store at -20°C; stable for up to 24 months (unopened)

Lyophilized powder (at 2–8°C; use within 3–6 months; minimize freeze-thaw refrigeration) cycles Reconstituted solution 2–8°C; use within 28 days Avoid Direct sunlight, repeated freeze-thaw cycles, temperatures above 25°C Transport Cold pack (2–8°C); insulated shipping container recommended Diluent compatibility Sterile bacteriostatic water (0.9% benzyl alcohol) or sterile saline (0.9% NaCl)

Legal Status

alphaKlothoLR is an investigational research compound and is not approved by the US Food and Drug Administration (FDA) or any equivalent regulatory agency for therapeutic use in humans or animals. It is legally available for purchase and use in the context of legitimate scientific research. The albumin-binding construct incorporated into alphaKlothoLR is protected under US Patent 12,377,158 B1, issued August 5, 2025, covering enhanced peptide constructs for albumin binding. Investigators are responsible for ensuring compliance with all applicable federal, state, and institutional regulations governing the use of research compounds. In the United States, research use of peptides and proteins must comply with FDA regulations under 21 CFR, including requirements for investigational new drug (IND) applications when applicable. International researchers should consult the regulatory frameworks applicable in their jurisdiction. alphaKlothoLR is not scheduled or classified as a controlled substance under the Controlled Substances Act (CSA) in the United States.

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Frequently Asked Questions

What is the difference between native α-Klotho and alphaKlothoLR? Native soluble α-Klotho has a short circulating half-life, limiting sustained systemic exposure.

alphaKlothoLR incorporates an albumin-binding domain (SA21 peptide) that associates the molecule with serum albumin, which has a half-life of approximately 19 days in humans. This extends functional exposure while preserving native FGF23 binding affinity and biological activity.

Does alphaKlothoLR suppress endogenous Klotho production? This question remains under investigation. Unlike classical hormones that suppress endogenous production through negative feedback loops, Klotho is a circulating protein rather than a hormone in the traditional sense. Theoretical considerations suggest that feedback suppression may be limited or absent, but long-term clinical data are not yet available to confirm this. This is a key area of ongoing research.

What are the most relevant biomarkers to monitor during alphaKlothoLR research protocols? The most informative biomarker panel includes: circulating α-Klotho levels (ELISA), serum phosphate, serum calcium, FGF23, PTH, 25-OH vitamin D, 1,25-dihydroxyvitamin D, BUN/creatinine (kidney function), and inflammatory markers (CRP, IL-6). Functional assessments such as grip strength, physical performance tests, and cognitive assessments provide complementary endpoint data.

How does alphaKlothoLR differ from hormone replacement strategies? Most hormone replacement strategies (e.g., testosterone, growth hormone, thyroid hormone) suppress endogenous production through feedback inhibition. alphaKlothoLR is designed to operate differently: it addresses circulating deficiency by extending the residence time of a naturally occurring protein without the classical feedback suppression associated with exogenous hormone administration. Whether this theoretical distinction holds clinically requires confirmation in long-term studies.

Is alphaKlothoLR the same as FGF23 supplementation? No. While α-Klotho functions as the obligate co-receptor for FGF23, they are distinct proteins with distinct biology. FGF23 is an osteocyte-derived hormone that signals through the Klotho- FGFR complex to regulate phosphate and vitamin D. Exogenous FGF23 administration would not replicate the pleiotropic, FGF23-independent actions of soluble α-Klotho.

What species has alphaKlothoLR been studied in? Preclinical research on α-Klotho biology spans mouse, rat, and in vitro human cell line models. The albumin-binding construct in alphaKlothoLR has demonstrated high-affinity binding to both human and canine albumin, supporting cross-species applicability in preclinical veterinary research contexts.

References

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22. Sahu A, et al. Age-related declines in α-Klotho drive progenitor cell mitochondrial dysfunction and impaired muscle regeneration. Nat Commun. 2018. doi:10.1038/s41467-018- 07253-3 23. Kim SJ, et al. Klotho, an antiaging molecule, attenuates oxidant-induced alveolar epithelial cell mtDNA damage and apoptosis. Am J Physiol Lung Cell Mol Physiol. 2017. doi:10.1152/ajplung.00063.2017 24. Cha SK, et al. Removal of sialic acid involving Klotho causes cell-surface retention of TRPV5 channel via binding to galectin-1. Proc Natl Acad Sci USA. 2008. doi:10.1073/pnas.0803223105 25. Wolf MTF, et al. Klotho up-regulates renal calcium channel TRPV5 by intra- and extracellular N-glycosylation-dependent mechanisms. J Biol Chem. 2014. doi:10.1074/jbc.m114.616649 26. Dalton GD, Xie J, An SW, Huang CL. New insights into the mechanism of action of soluble

Klotho. Front Endocrinol. 2017. doi:10.3389/fendo.2017.00323

27. Zhou P, et al. Klotho activation of Nrf2 inhibits the ferroptosis signaling pathway to ameliorate sepsis-associated acute kidney injury. Transl Androl Urol. 2023. doi:10.21037/tau-23- 28. Hajare AD, Dagar N, Gaikwad AB. Klotho antiaging protein: molecular mechanisms and therapeutic potential in diseases. Mol Biomed. 2025. doi:10.1186/s43556-025-00253-y 29. Xu Y, Sun Z. Molecular basis of Klotho: from gene to function in aging. Endocr Rev. 2015. doi:10.1210/er.2013-1079 30. Tohyama O, et al. Klotho is a novel beta-glucuronidase capable of hydrolyzing steroid beta- glucuronides. J Biol Chem. 2004;279(11):9777-84. 31. Kuzina ES, et al. Structures of ligand-occupied beta-Klotho complexes reveal a molecular mechanism underlying endocrine FGF specificity and activity. Proc Natl Acad Sci USA. 2019. doi:10.1073/pnas.1822055116 32. US Patent 12,377,158 B1. Enhanced peptide constructs for albumin binding. Issued August 5, 2025.