Telencephalon-specific antigen identified by monoclonal antibody.

Abstract

Immunohistochemical screening of monoclonal antibodies (mAbs) raised against fractions rich in the dendrodendritic synaptosomes of the rabbit olfactory bulb revealed that one of the mAbs (mAb 271A6) recognized a telencephalon-specific antigen or antigens. Thus, the stain with mAb 271A6 was observed throughout the gray matter of all regions of the neocortex, piriform cortex, hippocampus, striatum, septum, and the amygdaloid nucleus, in addition to the main and accessory olfactory bulbs. The mAb 271A6, however, labeled neither nontelencephalic regions of the central nervous system nor the peripheral nervous system so far examined. Dot-immunobinding assays of homogenates of various brain regions also showed the telencephalon-specific distribution of the antigen designated as 271A6. Antigen 271A6 is developmentally regulated. At birth, the antigen was expressed in a small quantity only in phylogenetically older telencephalic regions such as the olfactory bulb, piriform cortex, striatum, cingulate cortex, and hippocampus. It was hardly detectable in most areas of the neocortex. The densities and areas of 271A6-positive structures increased during the early postnatal period. These results demonstrate a molecular specificity of the most rostral brain segment, the telencephalon. mAb 271A6 may be a good tool for obtaining a better understanding of the molecular basis of the segmental organization or the segment-specific functions of the brain.During prenatal development, the vertebrate brain forms five segmental enlargements (vesicles)-telencephalon, diencephalon, mesencephalon (or midbrain), metencephalon (pons and cerebellum), and myelencephalon (or medulla oblongata) (1, 2). Each vesicle gives rise to specific regions of the adult brain. This segmental organization is therefore assumed to be the basic plan for the development of the central nervous system, and it may have great significance in ordering the structure and function of the brain. Among these vesicles or segments, the most rostral one (the telencephalon) expands most conspicuously in mammals and forms the complex telencephalic structures of the adult brain such as the cerebral neocortex, piriform cortex, hippocampus, striatum, septum, amygdaloid nucleus, and olfactory bulb.Although the molecular basis of the brain's segmental organization is unknown, it can be assumed that the vertebrate nervous system expresses certain molecules that are specific to one or more of the brain segments. In the course of an immunohistochemical screening of a number of mAbs raised against dendrodendritic synaptosomes (3) of the rabbit olfactory bulb, we noticed that one of them, mAb 271A6, strongly labeled the gray matter of all regions belonging to the telencephalic segment, whereas it did not stain other brain segments. In the present study, we have examined the spatial distribution of antigen 271A6 [i.e., molecule(s) recognized by mAb 271A6] in various regions of the central and peripheral nervous systems of the rabbit, using immunohistochemical staining methods and...

A Novel Phenylalanine-Based Targeting Signal Directs Telencephalin to Neuronal Dendrites

“…To label endogenous TLCN, we used a rabbit polyclonal antibody (anti-TLCN-C antiserum; 10,000ϫ) raised against a synthetic peptide corresponding to the C-terminal 17 amino acids in the intracellular region of mouse TLCN (Sakurai et al, 1998). To detect transgenederived rabbit TLCN and its mutants, we used a mouse monoclonal antibody (MAb271A6 ascites; 1000 -1500ϫ) that recognizes the extracellular region of rabbit TLCN but not mouse TLCN (Mori et al, 1987;. The sections were washed in PBST/NGS three times for 5-10 min, incubated for 1 h with horseradish peroxidase-conjugated secondary antibody (300ϫ; Jackson ImmunoResearch, West Grove, PA), and washed similarly.…”

“…One is a polyclonal antibody raised against the intracellular C-terminal peptide of mouse TLCN (anti-TLCN-C) that cross-reacts with rabbit TLCN (Sakurai et al, 1998). The other is MAb271A6 that recognizes a species-specific epitope in the extracellular region of rabbit TLCN (Mori et al, 1987). In the present study, MAb271A6 was mostly used to detect the ectopically expressed rabbit TLCN in transgenic mice.…”

“…The expression of TLCN is restricted to neurons in the most rostral brain segment, telencephalon (Mori et al, 1987;Oka et al, 1990). In the telencephalic neurons, TLCN protein is strictly localized to the somatodendritic compartment but not to axons (Murakami et al, 1991;Benson et al, 1998;Sakurai et al, 1998).…”

“…Telencephalin (TLCN) [intercellular adhesion molecule-5 (ICAM-5)] is a cell adhesion molecule belonging to the ICAM subgroup of the Ig superfamily (Mori et al, 1987;. The expression of TLCN is restricted to neurons in the most rostral brain segment, telencephalon (Mori et al, 1987;Oka et al, 1990).…”

Genetically encoded dendritic marker sheds light on neuronal connectivity inDrosophila

“…The expression of ICAM5 is restricted to the mammalian brain telencephalon (24) but there is no homolog in invertebrates and lower vertebrates. The developmental appearance of ICAM5 parallels the time of dendritic elongation, branching, and synapse formation and ICAM5 is described to selectively target dendrites (25) to endow their protrusions with plastic properties (26).…”