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Genetics2008; 179(4); 1861-1870; doi: 10.1534/genetics.108.088807

Differential gene expression of TRPM1, the potential cause of congenital stationary night blindness and coat spotting patterns (LP) in the Appaloosa horse (Equus caballus).

Abstract: The appaloosa coat spotting pattern in horses is caused by a single incomplete dominant gene (LP). Homozygosity for LP (LP/LP) is directly associated with congenital stationary night blindness (CSNB) in Appaloosa horses. LP maps to a 6-cM region on ECA1. We investigated the relative expression of two functional candidate genes located in this LP candidate region (TRPM1 and OCA2), as well as three other linked loci (TJP1, MTMR10, and OTUD7A) by quantitative real-time RT-PCR. No large differences were found for expression levels of TJP1, MTMR10, OTUD7A, and OCA2. However, TRPM1 (Transient Receptor Potential Cation Channel, Subfamily M, Member 1) expression in the retina of homozygous appaloosa horses was 0.05% the level found in non-appaloosa horses (R = 0.0005). This constitutes a >1800-fold change (FC) decrease in TRPM1 gene expression in the retina (FC = -1870.637, P = 0.001) of CSNB-affected (LP/LP) horses. TRPM1 was also downregulated in LP/LP pigmented skin (R = 0.005, FC = -193.963, P = 0.001) and in LP/LP unpigmented skin (R = 0.003, FC = -288.686, P = 0.001) and was downregulated to a lesser extent in LP/lp unpigmented skin (R = 0.027, FC = -36.583, P = 0.001). TRP proteins are thought to have a role in controlling intracellular Ca(2+) concentration. Decreased expression of TRPM1 in the eye and the skin may alter bipolar cell signaling as well as melanocyte function, thus causing both CSNB and LP in horses.
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Publication Date: 2008-07-27 PubMed ID: 18660533PubMed Central: PMC2516064DOI: 10.1534/genetics.108.088807Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research studies the genetic causes of congenital night blindness and coat spotting patterns in Appaloosa horses, connecting both conditions to the downregulation of TRPM1 gene expression, with the gene potentially influencing intracellular calcium concentration, thereby affecting both retina and skin cell function.

Objective and Methodology

  • This study investigates the genetic causes behind congenital stationary night blindness (CSNB) and coat spotting patterns (referred to as LP) in Appaloosa horses. The researchers focused on studying the expression of the LP gene which is thought to be responsible for these conditions.
  • The team used quantitative real-time RT-PCR to examine the relative expression of two key genes — TRPM1 and OCA2 (both located in the LP candidate region), and three other linked loci, TJP1, MTMR10, and OTUD7A.

Findings

  • No significant differences were found for the expression levels of TJP1, MTMR10, OTUD7A, and OCA2 genes.
  • However, the TRPM1 gene expression in the retina of homozygous appaloosa horses was significantly decreased, noted to be only 0.05% the level found in non-appaloosa horses.
  • This gene was also downregulated in both pigmented and unpigmented skin of LP/LP horses.
  • TRP proteins, produced by the TRPM1 gene, reportedly play a role in controlling intracellular calcium concentration, which can impact cellular signaling in bipolar cells of the eye and melanocytes in the skin.

Implications

  • The significant reduction in the TRPM1 gene expression is linked to both, the development of CSNB and the manifestation of LP in Appaloosa horses since this gene may influence both retina and melanocyte function.
  • The findings of this study contribute to the understanding of how gene expression can impact specific physical and health traits in horses, potentially opening avenues for further research and intervention strategies for genetic conditions in animal breeds.

Cite This Article

APA
Bellone RR, Brooks SA, Sandmeyer L, Murphy BA, Forsyth G, Archer S, Bailey E, Grahn B. (2008). Differential gene expression of TRPM1, the potential cause of congenital stationary night blindness and coat spotting patterns (LP) in the Appaloosa horse (Equus caballus). Genetics, 179(4), 1861-1870. https://doi.org/10.1534/genetics.108.088807

Publication

Genetics
ISSN: 0016-6731
NlmUniqueID: 0374636
Country: United States
Language: English
Volume: 179
Issue: 4
Pages: 1861-1870

Researcher Affiliations

Bellone, Rebecca R
  • Department of Biology, University of Tampa, Tampa, FL 33606, USA. rbellone@ut.edu
Brooks, Samantha A
    Sandmeyer, Lynne
      Murphy, Barbara A
        Forsyth, George
          Archer, Sheila
            Bailey, Ernest
              Grahn, Bruce

                MeSH Terms

                • Animals
                • Eye Abnormalities / genetics
                • Eye Abnormalities / veterinary
                • Gene Expression
                • Genes, Dominant
                • Genotype
                • Horse Diseases / congenital
                • Horse Diseases / genetics
                • Horses
                • Night Blindness / congenital
                • Night Blindness / genetics
                • Night Blindness / veterinary
                • Pigmentation / genetics
                • TRPM Cation Channels / genetics
                • TRPM Cation Channels / metabolism

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