HBZ Mouse
Description
Definition and Background
HBZ is encoded by the minus strand of the HTLV-1 provirus and is constitutively expressed in infected cells, including ATL. Transgenic mice expressing HBZ under tissue-specific promoters (e.g., CD4, Granzyme B) recapitulate key features of HTLV-1-associated diseases, including lymphoproliferation, immunosuppression, and bone metastases .
| Key Features of HBZ Mouse Models | Description |
|---|---|
| Promoter | CD4, Granzyme B, or others |
| Cell Targets | CD4+ T cells, cytotoxic T cells |
| Disease Phenotype | T-cell lymphoma, lymphadenopathy, osteolytic bone lesions |
| Latency Period | 6–18 months (model-dependent) |
Immunological Dysregulation
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Increased CD4+ T Cells: HBZ promotes proliferation of CD4+ T cells, particularly effector/memory (Tem) and regulatory (Treg) subsets .
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Impaired Treg Function: HBZ interacts with Foxp3 and NFAT, disrupting Treg suppressive activity despite elevated Foxp3+ cell counts .
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Inflammation and Immune Suppression: Systemic inflammation (e.g., dermatitis, lung infiltration) and reduced IFN-γ production impair immune responses .
Molecular Mechanisms
HBZ exerts oncogenic effects through:
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Transcriptional Modulation:
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NF-κB Pathway Suppression: Represses classical NF-κB signaling while activating the alternative pathway, promoting survival of infected cells .
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Tax Degradation: Induces PDLIM2 expression, targeting Tax for proteasomal degradation .
Hematological and Lymphoid Abnormalities
| Parameter | HBZ-Tg Mice | CARD11(E626K); HBZ-Tg Mice | Gzmb-HBZ Mice |
|---|---|---|---|
| Median Survival | 8–12 months | 6 months | 18 months |
| Tumor Incidence | ~33% | 100% | 66% |
| Affected Sites | Spleen, lymph nodes | Multi-organ infiltration | Mesenteric/lymphoid tumors, bone |
| Bone Lesions | Rare | Rare | Osteolytic lesions, hypercalcemia |
Bone Disease in Gzmb-HBZ Mice
Mice expressing HBZ under the Granzyme B promoter develop:
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Osteolytic Bone Lesions: Driven by upregulated RANKL, PTHrP, and DKK1 in T cells .
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Hypercalcemia: Linked to systemic release of bone-resorption factors .
Mechanistic Studies
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HBZ and Tax Synergy: CARD11(E626K) mutation accelerates HBZ-driven lymphoproliferation by disrupting T-cell homeostasis .
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Bone Metastasis Pathways: Gzmb-HBZ models validate RANKL/PTHrP as therapeutic targets for ATL-associated bone disease .
Therapeutic Screening
| Therapeutic Approach | Efficacy in HBZ Mice |
|---|---|
| CXCR4 Antagonists | Reduces lymphoma growth |
| NF-κB Inhibitors | Suppresses T-cell proliferation |
| HBZ Vaccines | Induces HBZ-specific CTLs, prolongs survival |
Challenges and Future Directions
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Long Latency: Disease manifests after 6–18 months, complicating longitudinal studies .
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Model Diversity: Promoter choice (CD4 vs. Granzyme B) influences disease presentation (e.g., dermatitis vs. bone lesions) .
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Humanization: Integration with humanized mice (e.g., NSG models) may improve translational relevance for ATL drug testing .
Product Specs
Hemoglobin subunit zeta, Hba-x, Hbz1, AI450015, Alpha-like embryonic globin chain x, Zeta-globin.
MGSSHHHHHH SSGLVPRGSH MSLMKNERAI IMSMWEKMAA QAEPIGTETL ERLFCSYPQT KTYFPHFDLH HGSQQLRAHG FKIMTAVGDA VKSIDNLSSA LTKLSELHAY ILRVDPVNFK LLSHCLLVTM AARFPADFTP EVHEAWDKFM SILSSILTEK YR.
Product Science Overview
Hemoglobin-Zeta (HbZ) is a type of hemoglobin subunit found in the early stages of mammalian embryonic development. In mice, the recombinant form of this protein is often used in research to study its structure, function, and role in embryogenesis. This article provides a detailed overview of Hemoglobin-Zeta, focusing on its molecular characteristics, biological significance, and applications in scientific research.
Hemoglobin-Zeta is an alpha-like globin chain encoded by the Hbz gene. The recombinant form of this protein is typically expressed in Escherichia coli and purified to a high degree of purity (>90%) for experimental use . The protein consists of 142 amino acids and has a predicted molecular weight of approximately 18.3 kDa . It is often tagged with a His tag at the N-terminus to facilitate purification and detection.
The amino acid sequence of Hemoglobin-Zeta includes several key regions that are crucial for its function. These regions include the heme-binding sites, which are essential for oxygen transport, and the alpha-helical regions that contribute to the protein’s stability and structural integrity .
Hemoglobin-Zeta plays a critical role during the early stages of embryonic development. It is one of the first hemoglobin subunits to be expressed in the yolk sac erythrocytes of the embryo. The expression of HbZ is tightly regulated and is eventually replaced by other hemoglobin subunits as development progresses .
In the context of embryonic development, Hemoglobin-Zeta forms part of the embryonic hemoglobins, such as Hemoglobin Gower-1 (ζ2ε2) and Hemoglobin Portland-2 (ζ2β2). These embryonic hemoglobins have distinct oxygen-binding properties that are adapted to the low-oxygen environment of the early embryo . The unique properties of HbZ and its interactions with other globin subunits are essential for efficient oxygen transport and delivery during this critical period.
Recombinant Hemoglobin-Zeta is widely used in scientific research to study various aspects of hemoglobin function and regulation. Some of the key applications include:
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Structural Studies: The high purity and well-defined structure of recombinant HbZ make it an ideal candidate for structural studies using techniques such as X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy. These studies provide insights into the protein’s three-dimensional structure and its interactions with other molecules .
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Functional Analysis: Researchers use recombinant HbZ to investigate its oxygen-binding properties and how these properties are influenced by factors such as pH, temperature, and the presence of other molecules. These studies help to elucidate the physiological role of HbZ in embryonic development .
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Comparative Studies: By comparing the properties of Hemoglobin-Zeta with other hemoglobin subunits, scientists can gain a better understanding of the evolutionary adaptations that have occurred in hemoglobin function. These comparative studies also shed light on the mechanisms underlying hemoglobinopathies and other blood disorders .
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Biotechnological Applications: The unique properties of Hemoglobin-Zeta, such as its high oxygen affinity, make it a potential candidate for biotechnological applications. For example, it could be used in the development of artificial blood substitutes or in the design of oxygen-carrying therapeutics .
