Sequential Expression of Type IV Collagen Networks: Testis as a Model and Relevance to Spermatogenesis

Abstract

The six ␣ chains of type IV collagen are organized into three networks: ␣1/␣2, ␣3/␣4/␣5, and ␣1/␣2/␣5/␣6. A shift from the ␣1/␣2 to the ␣3/␣4/␣5 network occurs in the developing glomerular basement membrane, but how the ␣1/␣2/␣5/␣6 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 ␣1/␣2 network is expressed from birth, the ␣1/␣2/␣5/␣6 network by 5-6 weeks of age, and the ␣3/␣4/␣5 network by 2 months of age. A canine model of Alport syndrome allowed study of the absence of ␣3/␣4/␣5 and ␣1/␣2/␣5/␣6 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 ␣3/ ␣4/␣5 and ␣1/␣2/␣5/␣6 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.

Disturbed spermatogenic signaling in pituitary adenylate cyclase activating polypeptide-deficient mice

“…Sox9 can be translocated into the nuclei of Sertoli cells and can regulate certain gene expression. Col. IV is one of the major elements of the basement membrane in the seminiferous tubules and regulates the formation of the blood-testis barrier (Harvey et al 2006). Col. IX also has some functions in the maintenance of the basement membrane, consequently the blood-testis barrier (McClive & Sinclair 2003).…”

“…The high levels of PACAP in the testis suggest that it plays an important role in spermatogenesis and/or sperm functions (Daniel et al 2000, Li et al 2000, Li & Arimura 2003. Indeed, PACAP has been shown to influence the development and functioning of spermatozoa (Gozes et al 1998, Koh et al 2003, 2006, Li et al 2004. PACAP expression was found mainly in immature and, to a smaller extent, in mature sperms (Hannibal & Fahrenkrug 1995).…”

An intracellular trafficking pathway in the seminiferous epithelium regulating spermatogenesis: a biochemical and molecular perspective

“…1). The basement membrane in mammalian testes is composed mostly by type IV collagen, laminin, entactin and heparan sulfate proteoglycans (Dobashi et al ., 2003; Dym, 1994; Harvey et al ., 2006; Siu and Cheng, 2004a). The hemidesmosome, an intermediate filament-based anchoring junction type restricted to cell-matrix interface, provides adhesion between epithelial cells and the ECM via interactions between integrins (function as receptors on the cell surface) and laminins or collagens (function as ligands in the ECM).…”

Connective tissue, glial and neuronal expressions in testis of the African giant rat (Cricetomys gambianus)

“…In the present study, the organization of types I and III collagen of the AGR was investigated. Collagens are known to develop unto maturity and function in reproduction (ENDERS, KAHSAI, LIAN et al, 1995;HARVEY, PERRY, ZHENG et al, 2006). Nonetheless, the ultrastructural organization of collagen vary substantially between animals and even between different parts of the same animal (PARRY and CRAIG, 2008).…”