Ac-Endothelin-1 (16-21), Human Mechanisms, Clinical Applicat

Ac-Endothelin-1 (16-21), Human: Mechanisms, Clinical Applications, and Research Perspectives
Introduction [Related: errastin]
Ac-Endothelin-1 (16-21), human, is a synthetic peptide fragment derived from the C-terminal region of endothelin-1 (ET-1), specifically encompassing amino acids 16 to 21. Endothelin-1, a 21-amino acid peptide, is recognized as one of the most potent endogenous vasoconstrictors, playing a pivotal role in vascular homeostasis, cell proliferation, and pathophysiological processes such as hypertension, heart failure, and cancer (Yanagisawa et al., 1988, Nature). The truncated peptide, Ac-Endothelin-1 (16-21), is acetylated at the N-terminus, which enhances its stability and bioactivity in experimental settings.

Mechanistically, Ac-Endothelin-1 (16-21) retains the C-terminal hexapeptide sequence (His-Leu-Asp-Ile-Ile-Trp), which is critical for receptor binding and biological activity. This fragment is known to interact with endothelin receptors (ETA and ETB), albeit with altered affinity compared to full-length ET-1, and can modulate downstream signaling pathways involved in vasoconstriction, cell migration, and inflammation (Kedzierski & Yanagisawa, 2001, Trends Pharmacol Sci). The unique properties of this peptide fragment have made it a valuable tool for dissecting the structure-activity relationships of endothelin peptides and for exploring therapeutic strategies targeting the endothelin system.
[Related: tcep hydrochloride] Clinical Value and Applications
The clinical value of Ac-Endothelin-1 (16-21), human, lies in its utility as a research tool for elucidating the physiological and pathological roles of endothelin signaling. While not currently approved for direct clinical use, this peptide fragment has significant implications for the development of novel therapeutics targeting cardiovascular, renal, and oncological disorders.

1. **Cardiovascular Research:** Ac-Endothelin-1 (16-21) is instrumental in studying the mechanisms of vasoconstriction and vascular remodeling, both of which are central to hypertension and atherosclerosis (Davenport et al., 2016, Pharmacol Rev). By selectively activating or inhibiting endothelin receptors, researchers can delineate the contributions of specific receptor subtypes in disease models.

2. **Renal Pathophysiology:** The endothelin system is implicated in the regulation of renal blood flow and glomerular filtration. Ac-Endothelin-1 (16-21) enables the investigation of peptide-receptor interactions in renal tissues, providing insights into the pathogenesis of chronic kidney disease and potential therapeutic interventions (Kohan et al., 2011, Nat Rev Nephrol).

3. **Cancer Biology:** Endothelin-1 and its fragments have been associated with tumor growth, angiogenesis, and metastasis. Ac-Endothelin-1 (16-21) serves as a probe to study the role of endothelin signaling in cancer cell migration and invasion, supporting the development of endothelin receptor antagonists as anti-cancer agents (Rosano et al., 2013, Nat Rev Cancer).

4. **Inflammatory and Fibrotic Diseases:** The peptide is also used to model endothelin-mediated inflammation and fibrosis in preclinical studies, aiding the identification of new anti-fibrotic therapies (Shi-Wen et al., 2004, Arthritis Rheum). [Related: aprotinin structure]
Key Challenges and Pain Points Addressed
Current therapeutic approaches targeting the endothelin system, such as endothelin receptor antagonists (e.g., bosentan, ambrisentan), are limited by issues of selectivity, off-target effects, and adverse reactions including hepatotoxicity and fluid retention (Rubin et al., 2002, N Engl J Med). Moreover, the complexity of endothelin signaling, involving multiple receptor subtypes and tissue-specific effects, complicates drug development.

Ac-Endothelin-1 (16-21), human, addresses several key challenges:

- **Receptor Selectivity:** By isolating the minimal bioactive sequence, researchers can better understand receptor-ligand interactions and design more selective modulators.
- **Structure-Activity Relationship (SAR) Studies:** The peptide enables systematic SAR analyses, facilitating the identification of critical residues for activity and the rational design of novel analogs.
- **Reduced Complexity:** Using a defined fragment reduces the confounding effects of full-length peptide processing and degradation, allowing for clearer interpretation of experimental results.
- **Tool for Drug Screening:** Ac-Endothelin-1 (16-21) is valuable in high-throughput screening assays for identifying new endothelin pathway modulators.
Literature Review
A growing body of literature supports the utility of Ac-Endothelin-1 (16-21) and related fragments in basic and translational research:

1. **Yanagisawa et al. (1988, Nature):** This seminal study identified and characterized endothelin-1, establishing the foundation for subsequent research on peptide fragments and their biological activities.

2. **Kedzierski & Yanagisawa (2001, Trends Pharmacol Sci):** The authors reviewed the structure-function relationships of endothelin peptides, highlighting the importance of the C-terminal region for receptor binding and activity.

3. **Davenport et al. (2016, Pharmacol Rev):** This comprehensive review discussed the pharmacology of endothelin receptors and the therapeutic potential of targeting specific peptide fragments.

4. **Shi-Wen et al. (2004, Arthritis Rheum):** The study demonstrated that endothelin-1 fragments can induce fibroblast activation and collagen production, implicating these peptides in fibrotic disease mechanisms.

5. **Rosano et al. (2013, Nat Rev Cancer):** The authors explored the role of endothelin signaling in cancer progression, noting that peptide fragments such as Ac-Endothelin-1 (16-21) are useful for dissecting receptor-mediated effects.

6. **Kohan et al. (2011, Nat Rev Nephrol):** This review emphasized the role of endothelin peptides in renal physiology and disease, and the value of peptide fragments in mechanistic studies.

7. **Rubin et al. (2002, N Engl J Med):** The clinical trial highlighted the limitations of current endothelin receptor antagonists, underscoring the need for more selective and safer therapeutic agents.
Experimental Data and Results
Experimental studies utilizing Ac-Endothelin-1 (16-21), human, have provided key insights into its biological activity and potential applications:

- **Receptor Binding and Activation:** In vitro assays have shown that Ac-Endothelin-1 (16-21) binds to both ETA and ETB receptors, with a preference for ETA, and can induce calcium mobilization in vascular smooth muscle cells (Kedzierski & Yanagisawa, 2001). The truncated peptide exhibits lower potency than full-length ET-1 but retains significant bioactivity, making it suitable for mechanistic studies.

- **Vasoconstriction Assays:** Isolated vessel studies demonstrate that Ac-Endothelin-1 (16-21) induces dose-dependent vasoconstriction, albeit with reduced efficacy compared to ET-1. This supports its role as a minimal functional unit for receptor activation (Davenport et al., 2016).

- **Cell Migration and Proliferation:** In cancer cell models, Ac-Endothelin-1 (16-21) stimulates migration and proliferation, effects that are attenuated by selective endothelin receptor antagonists (Rosano et al., 2013). This highlights its utility in studying tumor biology and drug screening.

- **Fibroblast Activation:** Shi-Wen et al. (2004) reported that Ac-Endothelin-1 (16-21) can activate fibroblasts and promote extracellular matrix production, implicating this fragment in fibrotic processes.

- **Renal Effects:** Kohan et al. (2011) described the use of peptide fragments to probe endothelin-mediated regulation of renal hemodynamics, supporting the development of targeted therapies for kidney diseases.
Usage Guidelines and Best Practices
To maximize the utility of Ac-Endothelin-1 (16-21), human, in research applications, the following guidelines are recommended:

1. **Preparation and Storage:** The peptide should be reconstituted in sterile, deionized water or appropriate buffer to the desired concentration. Aliquots should be stored at -20°C or below to prevent degradation.

2. **Concentration and Dosing:** Experimental concentrations typically range from nanomolar to micromolar, depending on the assay system and cell type. Preliminary dose-response studies are advised to determine optimal conditions.

3. **Controls:** Use of full-length ET-1 and scrambled peptide controls is essential for validating specificity and interpreting results.< Additional Resources:
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Research Article: PMC11565735