Restricted distribution of laminin α1 chain in normal adult mouse tissues

The distribution of laminin al chain in adult mouse tissue was determined by immunofluorescence using monoclonal antibody 200, reacting with the globular carboxyterminus E3 fragment of alpha 1 chain. Strong reactivity was noted only in a few tissues. Reactivity was restricted to epithelial basement membranes. Expression was noted in several epithelial basement membranes of the urinary tract, and male and female reproductive organs. In addition, expression was seen in some parts of the nervous system. Expression was seen in pia mater which surrounds the brain, and in the extracellular matrices covering the vitreous chamber and the lens of the eye. Staining was seen in the adrenal gland cortex, with strongest staining in the zona glomerulosa. Staining was negative in all other studied epithelial basement membranes, such as the lung (trachea or lung epithelium), epidermis, and all parts of the gastrointestinal tract (liver, gut) except for weak staining in the ventricle and Brunner's glands. No expression was seen in basement membranes of fat, Schwann, or endothelial cells in any studied parts of the body. Both small- and large-size vessel walls were negative both in endothelial basement membranes and blood vessel walls, with the exception of some larger brain blood vessels in locations where epithelial cells have invaginated. Neither smooth muscle, myocardium or striated muscle expressed alpha 1 chain. We conclude that al-containing heterotrimers including laminin-1 (alpha 1 beta 1 gamma 1) have a very restricted tissue distribution. (C) 1999 Elsevier Science B.V./International Society of Matrix Biology. All rights reserved.