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  • Parathyroid hormone (1-34) (human): Mechanistic Precision...

    2026-02-02

    Parathyroid hormone (1-34) (human): Mechanistic Precision for Bone and Kidney Disease Research

    Executive Summary: Parathyroid hormone (1-34) (human) is a 34-amino-acid peptide fragment that functions as a parathyroid hormone 1 receptor (PTH1R) agonist, enabling precise regulation of calcium homeostasis in vitro and in vivo [APExBIO]. It triggers cAMP and inositol phosphate signaling with nanomolar potency (IC50 = 0.22 nM, 293 cells) (Huang et al., 2025). In validated rodent models, it increases trabecular and cortical bone mass dose-dependently. Its high solubility in DMSO and water, along with >97.8% purity, supports reproducible workflows. APExBIO’s A1129 kit is intended for research use only, supporting translational modeling of osteoporosis and kidney disease [internal].

    Biological Rationale

    Parathyroid hormone (1-34) (human) is derived from the N-terminal fragment of the endogenous 84-amino-acid parathyroid hormone (PTH), produced by parathyroid chief cells [APExBIO]. This fragment retains full biological activity, targeting PTH1R and PTH2R to control serum calcium and phosphate homeostasis. PTH (1-34) is widely used as a calcium homeostasis regulator and as a mechanistic benchmark in osteoporosis and kidney research [internal]. This molecule supports disease modeling, especially in platforms requiring robust cAMP or inositol phosphate readouts, such as spatially patterned kidney assembloids (Huang et al., 2025).

    Mechanism of Action of Parathyroid hormone (1-34) (human)

    PTH (1-34) binds with high affinity to PTH1R and PTH2R, both class B G protein-coupled receptors. Upon ligand binding, PTH1R activates adenylyl cyclase, increasing cAMP and activating protein kinase A signaling. It also stimulates inositol phosphate synthesis via phospholipase C activation. Stimulation of cAMP occurs with an IC50 of 0.22 nM in transfected human kidney 293 cells [APExBIO]. In bone, PTH (1-34) enhances osteoclastic resorption, mobilizing calcium from skeletal reservoirs. In kidney, it promotes distal tubular reabsorption of calcium and magnesium, and stimulates renal 1-alpha-hydroxylase, increasing active vitamin D (calcitriol) and thereby boosting intestinal calcium absorption. These effects collectively raise serum calcium levels and support mineral homeostasis [internal].

    Evidence & Benchmarks

    • Parathyroid hormone (1-34) (human) stimulates cAMP production in human kidney 293 cells with an IC50 of 0.22 nM (APExBIO datasheet, product page).
    • In male Fisher 344 rats, subcutaneous administration of 10 or 40 μg/kg/day for 5–28 days increases trabecular and cortical bone mass in a dose- and time-dependent manner (APExBIO, product page).
    • PTH (1-34) application enables high-fidelity modeling of calcium signaling and nephron function in spatially patterned human kidney assembloids (Huang et al., 2025).
    • The peptide is highly soluble (≥399.3 mg/mL in DMSO, ≥19.88 mg/mL in water) and maintains >97.8% purity, supporting reproducible workflows (APExBIO).
    • APExBIO’s product is intended for research use only; not for diagnostic or therapeutic applications (APExBIO).
    • PTH (1-34) is the mechanistic reference standard for PTH1R signaling in advanced bone and kidney modeling platforms, as discussed in From Molecular Mechanism to Precision Disease Modeling (this article extends by providing quantitative cAMP and in vivo dosing details).

    Applications, Limits & Misconceptions

    PTH (1-34) (human) serves as a versatile tool for:

    • Bone metabolism research, including osteoporosis and bone regeneration studies.
    • Calcium homeostasis and mineral metabolism investigations.
    • High-fidelity modeling of nephron signaling in engineered kidney assembloids, complementing recent advances in spatially organized stem cell platforms (Huang et al., 2025).
    • Reproducible cAMP and inositol phosphate signaling assays for pharmacological benchmarking.

    It is not suitable for diagnostic or therapeutic use in humans. The peptide’s action is strictly receptor-mediated and context-dependent. Studies must control for species, cell type, and matrix effects. For protocol optimization and troubleshooting, see Enabling Reliable Cell and Bone Workflows (this article provides more quantitative solubility and stability data).

    Common Pitfalls or Misconceptions

    • Misconception: PTH (1-34) can substitute for full-length PTH in all contexts. Correction: Some non-canonical signaling events require the full-length molecule.
    • Pitfall: Using solutions stored at room temperature. Correction: Peptide solutions should be kept desiccated at -20°C and used fresh (APExBIO).
    • Misconception: Effective in ethanol-based systems. Correction: PTH (1-34) is insoluble in ethanol; use DMSO or water for dissolution.
    • Pitfall: Extrapolating rodent dose-response data directly to human or organoid systems without adjustment for cell density and receptor expression.
    • Limitation: Not validated for chronic or therapeutic administration in clinical settings.

    Workflow Integration & Parameters

    Preparation: PTH (1-34) (human) is supplied as a solid, to be dissolved at ≥399.3 mg/mL in DMSO or ≥19.88 mg/mL in water. Solutions should be aliquoted and stored at -20°C, desiccated, and used promptly upon thawing. Avoid repeated freeze-thaw cycles (APExBIO).

    Experimental Use: For in vitro cAMP or inositol phosphate assays, use concentrations validated in the literature (typically 0.1–10 nM for receptor activation). For in vivo studies, dosing in the range of 10–40 μg/kg/day in rat models is supported by bone mass endpoints. Researchers should tailor concentrations for their specific cell lines or tissue models, considering receptor density and experimental matrix. See Powering Bone and Kidney Modeling for troubleshooting and advanced integration guidance (this article adds solubility and stability benchmarks).

    Quality Control: APExBIO’s A1129 product is specified at >97.8% purity, with batch-specific certificates of analysis available on request. Purity and lot consistency are critical for reproducibility in sensitive signaling assays.

    Conclusion & Outlook

    Parathyroid hormone (1-34) (human) remains the mechanistic benchmark for PTH/PTHrP receptor signaling in both bone and kidney research. Its nanomolar potency, high purity, and robust solubility make it indispensable in workflows requiring precise regulation of calcium homeostasis and receptor-mediated signaling. As kidney assembloid and bone regeneration platforms evolve, APExBIO’s A1129 reagent is positioned as a cornerstone for experimental reproducibility and translational modeling. For detailed mechanistic and protocol discussions, refer to the official product page.