Sequential expression of type IV collagen networks: testis as a model and relevance to spermatogenesis.
The six alpha chains of type IV collagen are organized into three networks: alpha1/alpha2, alpha3/alpha4/alpha5, and alpha1/alpha2/alpha5/alpha6. A shift from the alpha1/alpha2 to the alpha3/alpha4/alpha5 network occurs in the developing glomerular basement membrane, but how the alpha1/alpha2/alpha5/alpha6 network fits into this sequence is less clear, because the three networks do not colocalize. Here, we studied the seminiferous tubule basement membrane of normal canine testis where all three networks do colocalize: the alpha1/alpha2 network is expressed from birth, the alpha1/alpha2/alpha5/alpha6 network by 5-6 weeks of age, and the alpha3/alpha4/alpha5 network by 2 months of age. A canine model of Alport syndrome allowed study of the absence of alpha3/alpha4/alpha5 and alpha1/alpha2/alpha5/alpha6 networks in testis. In Alport dogs, the seminiferous tubule basement membrane was thinner than in controls. Spermatogenesis began at the same time as with normal dogs; however, the number of mature sperm was significantly reduced in Alport dogs. Thus, it would appear that alpha3/alpha4/alpha5 and alpha1/alpha2/alpha5/alpha6 networks are not essential for onset of spermatogenesis, but long-term function may be compromised by the loss of one or both networks. This situation is analogous to the glomerular basement membrane in Alport syndrome. In conclusion, testis can serve as a model system to study the sequence of type IV collagen network expression.
Harvey
Scott J
SJ
Division of Pathology, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada.
Perry
Julie
J
Zheng
Keqin
K
Chen
Dilys
D
Sado
Yoshikazu
Y
Jefferson
Barbara
B
Ninomiya
Yoshifumi
Y
Jacobs
Robert
R
Hudson
Billy G
BG
Thorner
Paul S
PS
D000818:Animals; D003094:Collagen; D024141:Collagen Type IV / Q000737:chemistry / Q000502:physiology*; D004285:Dogs; D005786:Gene Expression Regulation; D008297:Male; D008854:Microscopy, Electron; D023421:Models, Animal; D009394:Nephritis, Hereditary / Q000378:metabolism* / Q000503:physiopathology; D012152:Rete Testis / Q000378:metabolism; D013091:Spermatogenesis; D013643:Tarsus, Animal / Q000378:metabolism; D013737:Testis / Q000378:metabolism*; D014960:X Chromosome
D024141:Collagen Type IV; D003094:Collagen