Expression and Analysis of TBX3 Gene in the Skin from Three Locations on Dun Mongolian Bider Horse.
Abstract: The Mongolian horse, one of the oldest and most genetically diverse breeds, exhibits a wide variety of coat colors and patterns, including both wild-type and unique features. A notable characteristic of dun Mongolian horses is the presence of Bider markings-symmetrical, black-mottled patterns observed on the shoulder blades. These markings are also seen in Przewalski's horses. The dun coat color, a common wild-type phenotype in domestic horses, is characterized by pigment dilution with distinct dark areas and is regulated by mutations in the gene. This study aimed to investigate the role of in the development of Bider markings in dun Mongolian horses. Methods: Skin tissue samples were collected from three key anatomical regions of dun Mongolian horses with Bider markings: the croup, dorsal midline, and shoulder. Histological staining was conducted to examine the skin and hair follicle structure and pigment distribution. RT-qPCR was used to measure mRNA expression, while immunoblotting and immunohistochemistry were employed to analyze TBX3 protein levels and localization. Results: Hematoxylin and eosin staining revealed the skin and hair follicle structures, including the epidermis, hair shaft, and hair bulb across different stages of the hair growth cycle. Differences in pigmentation were observed across the sampling sites. The croup and the light-colored area of the shoulder showed asymmetrical pigmentation, while the dorsal midline and dark-colored area of the shoulder displayed symmetrical pigmentation. mRNA expression levels were significantly higher in the croup compared to the shoulder and dorsal midline; however, corresponding TBX3 protein expression did not show significant differences. Immunohistochemical analysis localized TBX3 protein predominantly in the hair bulb and epidermis. Conclusions: This study demonstrates region-specific differences in expression that correlate with pigmentation patterns in dun Mongolian Bider horses. These findings provide valuable insights into the molecular mechanisms underlying Bider markings, offering a deeper understanding of the genetic regulation of coat color and primitive markings in equines.
Publication Date: 2024-12-11 PubMed ID: 39766856PubMed Central: PMC11675668DOI: 10.3390/genes15121589Google Scholar: Lookup
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Summary
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Overview
- This study investigates the expression of the TBX3 gene in the skin of dun Mongolian horses with Bider markings to understand the genetic and molecular basis of coat color patterns.
- Researchers analyzed TBX3 gene expression and protein localization in three different skin regions, revealing region-specific differences that correlate with the distinct pigmentation of Bider markings.
Background and Research Purpose
- The Mongolian horse is a breed known for its genetic diversity and variety of coat colors and patterns.
- Dun horses show pigment dilution combined with darker areas called primitive markings; a special feature in the Mongolian dun horse is Bider markings—symmetrical black-mottled patterns on the shoulder blades.
- Similar markings are also observed in Przewalski’s horses, indicating a possibly conserved genetic mechanism.
- The gene TBX3 is implicated in controlling pigmentation patterns related to these coat colors, but its specific role in Bider markings was unclear prior to this study.
- The study’s main objective was to analyze TBX3 expression and protein distribution in different skin regions (croup, dorsal midline, shoulder) to understand its role in Bider marking development.
Methods
- Skin samples were collected from three anatomical locations on dun Mongolian horses with Bider markings:
- Croup (rear of the horse)
- Dorsal midline (along the back)
- Shoulder (including both dark and light-colored areas)
- Histological analysis using hematoxylin and eosin staining examined overall skin structure, hair follicle morphology, and pigment distribution.
- Gene expression analysis via RT-qPCR measured TBX3 mRNA levels across the three locations.
- Protein analysis was done using immunoblotting (to quantify protein levels) and immunohistochemistry (to localize TBX3 protein within skin layers).
Findings
- Histology confirmed typical skin and hair follicle structures present at different hair growth stages in all regions.
- Pigmentation patterns varied according to skin location:
- Croup and light-colored shoulder areas showed asymmetrical, less patterned pigmentation.
- Dorsal midline and dark-colored shoulder areas exhibited symmetrical pigmentation consistent with Bider markings.
- TBX3 mRNA expression was significantly elevated in the croup region compared to shoulder and dorsal midline skin samples.
- Despite higher mRNA in the croup, TBX3 protein levels measured by immunoblotting did not significantly vary among the three regions, suggesting post-transcriptional regulation or protein stability differences.
- Immunohistochemistry revealed localization of TBX3 protein predominantly within the hair bulb and epidermal layers, areas critical for pigment cell development and deposition.
Conclusions and Implications
- The region-specific differences in TBX3 mRNA expression correlate with the variation in pigmentation seen in Bider markings of dun Mongolian horses, indicating TBX3 plays a role in regulating these patterns.
- The localization of TBX3 protein in hair follicles and epidermis suggests it influences pigment cell activity and hair pigmentation during the hair growth cycle.
- The lack of significant variation in protein levels despite mRNA differences points towards complex regulation mechanisms controlling TBX3 function in skin pigmentation.
- These results enhance understanding of the genetic mechanisms behind primitive markings and coat color diversity in horses, potentially aiding breeding and conservation efforts and providing a basis for further molecular studies in equine coat pattern genetics.
Cite This Article
APA
An T, Dugarjaviin M, Han H.
(2024).
Expression and Analysis of TBX3 Gene in the Skin from Three Locations on Dun Mongolian Bider Horse.
Genes (Basel), 15(12), 1589.
https://doi.org/10.3390/genes15121589 Publication
Researcher Affiliations
- Inner Mongolia Key Laboratory of Equine Science Research and Technology Innovation, Inner Mongolia Agricultural University, Hohhot 010018, China.
- Inner Mongolia Key Laboratory of Equine Science Research and Technology Innovation, Inner Mongolia Agricultural University, Hohhot 010018, China.
- Inner Mongolia Key Laboratory of Equine Science Research and Technology Innovation, Inner Mongolia Agricultural University, Hohhot 010018, China.
MeSH Terms
- Animals
- Horses / genetics
- T-Box Domain Proteins / genetics
- T-Box Domain Proteins / metabolism
- Skin / metabolism
- Skin Pigmentation / genetics
- Hair Follicle / metabolism
- Hair Follicle / growth & development
- Hair Color / genetics
- Mongolia
- Phenotype
Grant Funding
- U23A20224 / National Natural Science Joint Fund Key Support Project
Conflict of Interest Statement
The authors declare no conflicts of interest.
References
This article includes 12 references
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Citations
This article has been cited 1 times.- An T, Dugarjaviin M. Differential Expression and Analysis of TBX3 Gene in Skin Tissues of Dun Mongolian Horses with and Without Bider Markings.. Animals (Basel) 2026 Jan 18;16(2).
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