Why Shar Pei Dogs Have So Many Wrinkles
ScienceDaily (Nov. 16, 2008) — A group of researchers at  Universitat Autònoma de Barcelona (UAB) have discovered the origin  of the mucinosis present in Shar Pei dogs, a hereditary disorder responsible for the characteristic wrinkles found in this breed.
 
The research report appears in the journals Veterinary Dermatology and Journal of Heredity. The report details the genetic alteration  in this breed which multiplies the activity of an enzyme  responsible for an excessive production of hyaluronic acid, a  substance which gathers under the skin and produces wrinkles.  Understanding this molecular mechanism will give way to new  reproduction programmes aimed at improving the health of these  animals. It also will be used to learn more about human disorders  such as Familial Mediterranean Fever (FMF) or mucinosis, and to gain more knowledge on the ageing process.
 
 Shar Pei dogs have unique characteristics. The breed originated in  the south of China more than two thousand years ago with the Han  dynasty and was used as guard dogs and shepherds. After the  communist revolution of Mao Tse-Tung the Shar Pei breed almost  disappeared. However, at the beginning of the 1970s a breeder from  Hong Kong, Matgo-Law, sent a number of Shar Peis to the United  States and there began the process of recovering the breed, which  is considered to be the rarest in the world.
 
Shar Peis became a popular breed in Europe and the United States   at  the beginning of the 1990s. During the recovery process, the characteristic wrinkles of the first Shar Pei dogs were enhanced  and the offspring of these appeared with thicker skin and a greater number of wrinkles. This increase in thickness and the formation of excessive wrinkles are the cause of the inherited skin disorder cutaneous mucinosis, in which there is a build-up of mucin in the layers of the skin. The mechanism which produces this excess of mucin was unknown of until now.
 
 A group of researchers at UAB, led by professors Lluís Ferrer and  Anna Bassols, have discovered the mechanisms of this disorder.  Mucinosis in Shar Peis is due to an accumulation of hyaluronic acid  (one of the main components found in the space between tissue  cells) in cutaneous structures. This causes them to present high  levels of hyaluronic acid in their bloodstream as well. Research  with fibroblast cell cultures isolated from the Shar Pei's skin  have allowed scientists to demonstrate that synthesis of hyaluronic  acid is produced in abnormally high amounts due to an excess in the  activity (overexpression) of the HAS2 enzyme, one of the three  enzymes responsible for the synthesis of acid in mammals. Now  researchers are working to find the exact location of the genetic mutation causing this metabolic alteration, in a collaboration  project between Armand Sánchez and Olga Francino from the UAB  Department of Animal and Food Science, and Mia Olson and Kerstin  Lindblah-Tod from the University of Uppsala, Sweden.
 
The results of the research contain many practical applications for the future. Due to the high level of inbreeding, the Shar Pei breed  is afflicted with numerous disorders, and many of them are  hereditary. Knowledge of the genetic and hereditary bases of  mucinosis will be used to design reproduction programmes aimed at  improving the health of these animals. This breed is also a  valuable model for the study of human disorders such as FMF or  hereditary mucinosis and research results could lead to  applications which could cure these disorders. In addition, understanding the molecular mechanisms of mucinosis will shed more  light on the biology of the tissues surrounding cells, the  extracellular matrix, and will help to understand processes such as  cell recognition and ageing.
 
The research was carried out by researchers Lluís Ferrer, Giordana   Zanna, Dolors Fondevila, Anna Bassols and Maria José Docampo from the UAB Department of Animal Medicine and Surgery, and the Department of Biochemistry and Molecular Biology. The results have been published in the journals Veterinary Dermatology and Journal  of Heredity and will be presented at the World Congress of  Veterinary Dermatology (WCVD6) which will take place in Hong Kong  on 19 November 2008.