PTD-DBM 10mg – Research Grade Wnt Pathway Peptide

PTD-DBM is a designed cell-penetrating research peptide consisting of a protein transduction domain (PTD) — typically the HIV TAT (47-57) RKKRRQRRR cationic sequence or a related cell-penetrating motif — fused to a "Dishevelled-binding motif" (DBM) peptide derived from the CXXC5 protein. The molecule was developed by Kang-Yell Choi and colleagues at Yonsei University as a research tool to selectively disrupt the protein-protein interaction between CXXC5 (a CXXC-type zinc-finger protein that functions as a negative feedback regulator of the Wnt/β-catenin signaling pathway) and Dishevelled (DVL, a central cytoplasmic Wnt-pathway signaling component). By disrupting the CXXC5-DVL interaction, the peptide releases Dishevelled from CXXC5-mediated sequestration and promotes Wnt/β-catenin pathway activation.

The mechanistic rationale is that CXXC5 acts as a negative feedback regulator: Wnt-pathway activation induces CXXC5 expression, and the induced CXXC5 binds Dishevelled and suppresses further Wnt signaling. In contexts where Wnt-pathway activation is desired (for example, in hair-follicle regeneration research, in bone-regeneration research, and in tissue-repair research more broadly), selective disruption of the CXXC5-DVL interaction with a research-tool peptide like PTD-DBM provides a pharmacological approach to relieving CXXC5-mediated inhibition and enhancing Wnt-pathway activity. The published preclinical research from the Choi laboratory and collaborators has characterized PTD-DBM in hair-follicle research, in bone-regeneration research, and in skin-wound research.

This page is a research-only educational reference for PTD-DBM as a research peptide for Wnt-pathway and tissue-regeneration preclinical research. The peptide is not approved as a medicine and is not the subject of any clinical-research program in human subjects. No medical or therapeutic claims are made on this page.

PTD-DBM is a fusion peptide consisting of two functional modules. The N-terminal module is a protein transduction domain (PTD) — most commonly the HIV TAT (47-57) sequence RKKRRQRRR, a short cationic peptide that confers cell membrane penetration through interaction with cell-surface heparan sulfate proteoglycans and subsequent endocytic uptake. The C-terminal module is the "Dishevelled-binding motif" (DBM) — a short peptide sequence derived from the region of the CXXC5 protein responsible for its interaction with Dishevelled (DVL). The two modules are linked through a short flexible linker. The full-length peptide is in the range of 25-30 amino acids depending on the specific PTD and DBM sequences used in different published preparations.

CXXC5 (CXXC-type zinc finger protein 5, also called RINF) is a member of the CXXC-type zinc-finger protein family that includes proteins involved in chromatin biology and in Wnt-pathway regulation. CXXC5 is a target gene of Wnt/β-catenin signaling — its expression is induced by Wnt-pathway activation — and functions as a negative feedback regulator of the same pathway. The protein binds Dishevelled in the cytoplasm and sequesters it in a non-signaling complex, suppressing further Wnt-pathway activation. The CXXC5-DVL interaction is mediated by a defined region of CXXC5 (the "DVL-binding region" from which the DBM peptide sequence is derived) and the C-terminal PDZ-binding-motif region of DVL.

The PTD-DBM research-peptide strategy exploits this protein-protein interaction. The PTD module delivers the peptide into the cytoplasm of target cells after extracellular application. The DBM module then competes with endogenous CXXC5 for the CXXC5-binding region of DVL, displacing endogenous CXXC5 from DVL and releasing DVL from CXXC5-mediated sequestration. The net effect is a derepression of Wnt/β-catenin signaling at the level of DVL — Wnt-pathway activity is enhanced through removal of the CXXC5-mediated negative feedback rather than through direct upstream Wnt-receptor activation.

The Wnt/β-catenin pathway is a fundamental developmental and tissue-homeostasis signaling pathway. In the canonical pathway, secreted Wnt ligands bind Frizzled-family receptors and LRP5/6 co-receptors on the cell surface, activating cytoplasmic Dishevelled, inhibiting the β-catenin destruction complex (composed of axin, APC, GSK3β, and CK1α), and allowing β-catenin to accumulate and translocate to the nucleus where it binds TCF/LEF transcription factors and drives expression of Wnt target genes. The pathway is critical for embryonic patterning, stem-cell maintenance, hair-follicle cycling, bone homeostasis, intestinal epithelial renewal, and many other tissue contexts. Dysregulation of Wnt signaling is implicated in cancer (e.g., APC loss in colorectal cancer), in tissue-degenerative conditions, and in regenerative-medicine research.

CXXC5 was identified as a Wnt-pathway negative feedback regulator in the Choi laboratory and characterized in the context of hair-follicle biology, bone-regeneration research, and skin-wound-healing research. The PTD-DBM peptide was developed as a research tool to disrupt this regulatory interaction and to investigate the consequences of pharmacological CXXC5-DVL disruption in these preclinical research contexts. The published work has characterized peptide-mediated Wnt-pathway activation in cell-culture systems (immortalized fibroblast and dermal-papilla cell lines, primary hair-follicle cell cultures) and in in-vivo rodent models (mouse hair-cycling models, mouse bone-defect models).

It is important to be clear about what PTD-DBM is not. It is not a Wnt ligand or a Wnt receptor agonist — the mechanism is downstream pathway derepression rather than upstream receptor activation. It is not a small-molecule GSK3β inhibitor (compounds like CHIR99021 that activate Wnt-pathway by inhibiting β-catenin degradation are mechanistically distinct). It is not a medicine — there are no approved indications for PTD-DBM or for any CXXC5-DVL disruptor compound. And it is not a topical hair-loss treatment — the published research is preclinical mechanistic work in cell culture and animal models, and the peptide is supplied as a research-supply compound for laboratory use.

The Wnt/β-catenin signaling pathway was first characterized through developmental-biology research in the 1980s and 1990s, with the wingless gene of Drosophila and the int-1 gene of mouse mammary tumor virus identifying the founding members of the Wnt family. The β-catenin signaling axis, the destruction complex (axin, APC, GSK3β, CK1α), the Frizzled-family receptors, and the LRP5/6 co-receptors were characterized through the 1990s and early 2000s, establishing the modern molecular framework of canonical Wnt signaling. The pathway's roles in embryonic patterning, stem-cell maintenance, and tissue homeostasis became central themes of developmental and regenerative biology.

CXXC5 was identified and characterized as a Wnt-pathway-regulated gene and as a negative feedback regulator of the pathway through research in the Choi laboratory at Yonsei University (Seoul, South Korea) and in collaborating groups, with foundational publications in the 2010s. The characterization of the CXXC5-Dishevelled interaction as a regulatory node, and the identification of a defined "Dishevelled-binding motif" in CXXC5, provided the molecular basis for designing a peptide-based disruptor of the interaction.

PTD-DBM was developed as a research-tool peptide in this context. The fusion design — protein transduction domain plus Dishevelled-binding motif — was a deliberate research-pharmacology strategy combining cell-penetration capability with target-protein-interaction-disruption activity. The peptide has been characterized in published preclinical work in hair-follicle research (mouse hair-cycling models, dermal-papilla cell cultures), in bone-regeneration research (mouse calvarial-defect models, osteoblast and osteoclast cultures), and in skin-wound-healing research. The Choi laboratory has historically focused on Wnt-pathway regulation and pharmacology, and the PTD-DBM program is part of a broader research portfolio investigating peptide-based research approaches to Wnt-pathway intervention.

A small biotechnology company associated with the Choi laboratory's research has pursued translational development of CXXC5-DVL disruptor compounds for hair-loss and bone-regeneration indications; the published research and translational efforts use various peptide and small-molecule chemotypes that target the same CXXC5-DVL interaction. PTD-DBM as supplied for research-supply use is a research-tool compound, not an investigational drug candidate, and is not in clinical-research development for any indication as a research-supply preparation.

The broader research landscape of Wnt-pathway pharmacological tools includes upstream pathway activators (Wnt-pathway-activating small molecules like CHIR99021 that inhibit GSK3β, recombinant Wnt ligands), upstream pathway inhibitors (Wnt-pathway-inhibiting small molecules like LGK974/Wnt-C59 that inhibit porcupine and block Wnt ligand secretion), and downstream pathway modulators (tankyrase inhibitors that stabilize axin and enhance β-catenin degradation, β-catenin/TCF interaction inhibitors). PTD-DBM occupies a specific niche within this landscape as a CXXC5-DVL-interaction-disrupting research-tool peptide.

The canonical Wnt/β-catenin signaling pathway operates through the following molecular cascade. In the absence of Wnt ligand stimulation, cytoplasmic β-catenin is captured by the destruction complex (composed of the scaffolding proteins axin and APC and the kinases GSK3β and CK1α). The destruction complex phosphorylates β-catenin at specific N-terminal serine and threonine residues, marking it for recognition by the β-TrCP E3 ubiquitin ligase and subsequent proteasomal degradation. In this "off" state, cytoplasmic β-catenin levels remain low, and Wnt target genes are not transcribed.

When a Wnt ligand binds the Frizzled receptor and the LRP5/6 co-receptor on the cell surface, the cytoplasmic signaling cascade is engaged. Dishevelled (DVL) is recruited to the activated Frizzled receptor at the membrane and is phosphorylated and conformationally activated. Activated DVL participates in disassembly of the destruction complex through recruitment of axin to the activated LRP5/6 cytoplasmic tail and through other mechanisms that effectively sequester the destruction complex components away from cytoplasmic β-catenin. The result is stabilization and accumulation of β-catenin in the cytoplasm, translocation to the nucleus, binding to TCF/LEF transcription factors, and transcription of Wnt target genes.

The Wnt target gene expression program includes feedback regulators of the pathway. Among these is CXXC5, whose expression is induced by Wnt-pathway activation in many cellular contexts. The induced CXXC5 binds Dishevelled in the cytoplasm and sequesters it in a non-signaling complex, suppressing further DVL-mediated Wnt-pathway activation. This is a classical negative-feedback architecture: pathway activation induces a regulator that downregulates the pathway. The CXXC5-DVL interaction is mediated by a defined CXXC5 region (the DVL-binding region) and the C-terminal PDZ-binding-motif region of DVL.

PTD-DBM disrupts this negative-feedback regulation. The fusion peptide enters cells through PTD-mediated transduction (the cationic TAT or related sequence supports membrane interaction and endocytic uptake), reaches the cytoplasm, and the DBM module competes with endogenous CXXC5 for DVL binding. Displacement of endogenous CXXC5 from DVL releases DVL from CXXC5-mediated sequestration and allows DVL to participate in Wnt-pathway signaling. The net effect is an enhancement of Wnt/β-catenin pathway activity through removal of CXXC5-mediated negative feedback.

In hair-follicle biology, Wnt/β-catenin signaling is a central regulator of the hair cycle. The dermal papilla (the mesenchymal niche at the base of the hair follicle) sends Wnt-pathway signals that drive activation of the bulge hair-follicle stem-cell population and entry into anagen (the active growth phase of the hair cycle). Wnt-pathway dysregulation is implicated in hair-loss conditions including androgenetic alopecia. The CXXC5-DVL regulatory interaction has been characterized in dermal-papilla and hair-follicle research, and PTD-DBM has been investigated as a research tool to enhance Wnt signaling in hair-follicle research contexts.

In bone biology, Wnt/β-catenin signaling supports osteoblast differentiation and bone formation, and the LRP5 co-receptor has well-characterized roles in human bone-mass regulation (loss-of-function and gain-of-function LRP5 variants produce low-bone-mass and high-bone-mass phenotypes respectively). PTD-DBM has been investigated in bone-regeneration research as a research tool to enhance Wnt-pathway-mediated osteoblast activity in models of bone defect and bone repair.

In skin and other epithelial contexts, Wnt-pathway signaling supports epithelial stem-cell function and tissue regeneration after injury. PTD-DBM has been investigated in skin-wound-healing research and in related epithelial-regeneration contexts.

Distinguishing PTD-DBM from related Wnt-pathway pharmacological tools: the peptide is mechanistically distinct from upstream Wnt-pathway activators (GSK3β inhibitors like CHIR99021, recombinant Wnt ligands), from Wnt-pathway inhibitors (porcupine inhibitors like LGK974, tankyrase inhibitors, β-catenin/TCF disruptors), and from downstream β-catenin transcriptional modulators. The CXXC5-DVL disruption mechanism is specific to the proposed negative-feedback regulatory node, and is the basis for the peptide's research-tool utility in the published Wnt-pathway research literature.

PTD-DBM is a fusion peptide consisting of an N-terminal protein transduction domain (PTD) and a C-terminal Dishevelled-binding motif (DBM) joined by a short flexible linker. The most commonly used PTD in the published research is the HIV TAT (47-57) sequence YGRKKRRQRRR (an 11-residue cationic peptide), although other PTD sequences (penetratin, R8 oligoarginine, and others) have been used in variant preparations. The DBM module is a short peptide sequence derived from the CXXC5 region responsible for Dishevelled binding; the specific sequence used in different published preparations is described in the corresponding publications. The full-length fusion peptide is typically 25-30 amino acids depending on the specific PTD and DBM sequences employed.

The PTD module functions as a cell-penetration carrier. The cationic TAT-derived sequence interacts with cell-surface heparan sulfate proteoglycans and triggers endocytic uptake, with subsequent endosomal escape providing the peptide with access to the cytoplasm. PTD-mediated cell penetration is a well-characterized technique in research peptide design used to deliver otherwise membrane-impermeable peptide cargoes into cells for intracellular target engagement.

The DBM module functions as the target-engagement element. The DBM sequence competes with endogenous CXXC5 for binding to Dishevelled, disrupting the CXXC5-DVL protein-protein interaction at the molecular level. The competition is concentration-dependent and is the basis for the dose-dependent Wnt-pathway activation observed in published cell-culture and in-vivo work.

Research-grade PTD-DBM is produced by solid-phase peptide synthesis (SPPS), purified by reversed-phase HPLC to ≥98% purity, and verified by analytical HPLC and mass spectrometry. The peptide is supplied as a sterile lyophilized powder in sealed vials. Lyophilized storage is at -20 °C or below in moisture-protected containers; reconstituted solutions in aqueous diluent are stored refrigerated and used within a short window per standard peptide-stability practice. The cationic PTD module provides good aqueous solubility, and the fusion peptide has adequate solution stability under appropriate conditions.

In published preclinical research, PTD-DBM has been used in several principal application areas:

Hair-follicle research and hair-cycle pharmacology. Mouse hair-cycling models (with telogen-to-anagen transition characterized by hair-pigmentation changes and histological analysis) have been used to evaluate topical and intradermal administration of PTD-DBM with reported effects on hair-cycle progression and on hair-follicle Wnt-pathway activation markers. Cultured human and mouse dermal papilla cells have been used to investigate the cellular effects on dermal-papilla-derived Wnt signaling.

Bone-regeneration research. Mouse calvarial-defect models (with surgical creation of a defined skull defect and quantitative measurement of new bone formation over time) have been used to evaluate PTD-DBM administration for bone-regeneration effects, with reported enhancement of new-bone formation in the defect through Wnt-pathway-mediated osteoblast activity. Cultured osteoblast and osteoclast cell systems have been used to investigate cell-autonomous effects on bone-cell biology.

Skin-wound-healing research. Cutaneous wound-healing models (with standardized full-thickness wound creation and time-course measurement of wound closure, granulation-tissue formation, and re-epithelialization) have been used to evaluate PTD-DBM administration for wound-healing effects through Wnt-pathway-mediated epithelial-regeneration enhancement.

Cellular Wnt-pathway research. HEK293, NIH/3T3, and other cell lines stably expressing TCF/LEF reporter constructs (TopFlash reporter assay) are used to quantitatively measure Wnt-pathway activity in response to PTD-DBM treatment. The reporter assay is the standard quantitative readout for canonical Wnt-pathway activation in cell-culture pharmacology.

CXXC5-Dishevelled interaction biochemistry. In-vitro pull-down assays, co-immunoprecipitation, and other protein-protein interaction methods are used to characterize the molecular details of the CXXC5-DVL interaction and the disruptive effect of PTD-DBM. This is mechanistic protein-biochemistry research that informs the design of the peptide and of related disruptor compounds.

Comparative Wnt-pathway pharmacology. PTD-DBM is used as a research-tool comparator in studies investigating other Wnt-pathway pharmacological agents (CHIR99021, LGK974, tankyrase inhibitors, recombinant Wnts) to characterize the distinct effects of CXXC5-DVL disruption versus upstream pathway activation or downstream β-catenin modulation.

All applications are research-supply context: laboratory and academic use in cell culture and rodent in-vivo models. The peptide is not for human consumption, is not a medicine, and nothing on this page describes a clinical protocol or therapeutic use.

PTD-DBM sits within the Wnt-pathway pharmacological tool landscape alongside upstream activators, upstream inhibitors, and downstream modulators of canonical Wnt signaling.

PTD-DBM is a designed cell-penetrating research peptide consisting of a protein transduction domain (typically HIV TAT 47-57) fused to a Dishevelled-binding motif derived from CXXC5. The peptide was developed by the Choi laboratory at Yonsei University to selectively disrupt the CXXC5-Dishevelled protein-protein interaction, relieving CXXC5-mediated negative feedback on the Wnt/β-catenin signaling pathway. The mechanism is enhancement of Wnt-pathway activity through derepression of a regulatory interaction at the DVL signaling node, mechanistically distinct from upstream Wnt-receptor activation or downstream β-catenin modulation.

Published preclinical research has investigated PTD-DBM in hair-follicle research (mouse hair-cycling models, dermal-papilla cell cultures), in bone-regeneration research (mouse calvarial-defect models, osteoblast cultures), in skin-wound-healing research, and in cellular Wnt-pathway pharmacology (TCF/LEF reporter assays in HEK293 and other cell systems). The peptide is a research-tool compound for investigating the CXXC5-DVL regulatory node and the consequences of pharmacological CXXC5-DVL disruption in tissue-regeneration contexts.

This page is research educational only. PTD-DBM is not an approved medicine and is not in clinical-research development for any indication as a research-supply preparation. Research-supply PTD-DBM is intended for laboratory and academic preclinical research use; no medical or therapeutic claims are made.