Immunolocalization of tight junction proteins in the adult and developing human brain
- 386 Downloads
The formation of endothelial tight junctions (TJs) is crucial in blood-brain barrier (BBB) differentiation, and the expression and targeting of TJ-associated proteins mark the beginning of BBB functions. Using confocal microscopy, this study analyzed endothelial TJs in adult human cerebral cortex and the fetal telencephalon and leptomeninges in order to compare the localization of two TJ-associated transmembrane proteins, occludin and claudin-5. In the arterioles and microvessels of adult brain, occludin and claudin-5 form continuous bands of endothelial immunoreactivity. During fetal development, occludin and claudin-5 immunoreactivity is first detected as a diffuse labeling of endothelial cytoplasm. Later, at 14 weeks, the immunosignal for both proteins shifts from the cytoplasm to the interface of adjacent endothelial cells, forming a linear, widely discontinuous pattern of immunoreactivity that achieves an adult-like appearance within a few weeks. These results demonstrate that occludin and claudin-5 expression is an early event in human brain development, followed shortly by assembly of both proteins at the junctional areas. This incremental process suggests more rapid establishment of the human BBB, consistent with its specific function of creating a suitable environment for neuron differentiation and neurite outgrowth during neocortical histogenesis.
KeywordsOccludin Claudin-5 Tight junctions Blood-brain barrier Human brain development
The authors are grateful to Prof. S. Nag for critical reading of the manuscript. The authors also thank Ms M.V.C. Pragnell, BA, for linguistic help and Ms M. Ambrosi for excellent technical assistance. This work was supported by grants from the Ministero dell’Istruzione, dell’Università e della Ricerca (M.I.U.R.) (to L.R.).
- Bär T (1980) The vascular system of the cerebral cortex. Adv Anat Embryol Cell Biol 59:1–62Google Scholar
- Cancilla PA, Bready J, Berliner J (1993) Brain endothelial-astrocyte interactions. In: Pardridge WM (ed) The blood-brain barrier. Cellular and molecular biology. Raven, New York, pp 25–46Google Scholar
- Gerhart DZ, Le Vasseur RJ, Broderius MA, Drewes LR (1989) Glucose transporter localization in brain using light and electron immunocytochemistry. J Neurosci Res 22:464–472Google Scholar
- Marín-Padilla M (1987) Embryogenesis of the early vascularization of the central nervous system. In: Yasargil MG (ed) Microneurosurgery, vol 3. Thieme, Stuttgart, pp 23–44Google Scholar
- Nag S (2003) Morphology and molecular properties of cellular components of normal cerebral vessels. In: Nag S (ed) The blood-brain barrier. Biology and research protocols. Humana, Totowa, NJ, pp 3–36Google Scholar
- Nitta T, Hata M, Gotoh S, Seo Y, Sasaki H, Hashimoto N, Furuse M, Tsukita S (2003) Size-selective loosening of the blood-brain barrier in claudin-5-deficient mice. J Cell Biol 161:653–660Google Scholar
- Norman MG, O’Kusky JR (1986) The growth and development of microvasculature in human cerebral cortex. J Neuropathol Exp Neurol 45:222–232Google Scholar
- Risau W (1993) Development of the vascular system of organs and tissues. In: Schaper W, Schaper J (eds) Collateral circulation. Kluwer Academic, Norwell, pp 17–28Google Scholar
- Saitou M, Furuse M, Sasaki H, Schulzke J-D, Fromm M, Takano H, Noda T, Tsukita S (2000) Complex phenotype of mice lacking occludin, a component of tight junction strands. Am Soc Cell Biol 11:4131–4142Google Scholar
- Saunders NR (1977) Ontogeny of the blood-brain barrier. Exp Eye Res S25:523–550Google Scholar
- Wolburg H, Wolburg-Buchholz K, Kraus J, Rascher-Eggstein G, Liebner S, Hamm S, Duffner F, Grote E-H, Risau W, Engelhardt B (2003) Localization of claudin-3 in tight junctions of the blood-brain barrier is selectively lost during experimental autoimmune encephalomyelitis and human glioblastoma multiforme. Acta Neuropathol 105:586–592PubMedGoogle Scholar