The neuronal intermediate filament, alpha-internexin is transiently expressed in amacrine cells in the developing mouse retina.

We have investigated the expression of intermediate filament proteins in the developing mouse retina by immunohistochemistry. Antibodies against alpha-internexin, the three neurofilament subunits (NF-L, NF-M, NF-H), vimentin, and glial fibrillary acidic protein (GFAP) were used to determine the relative expression of these proteins at different post-natal stages of mouse retinal development. alpha-Internexin is widely distributed in the process of amacrine cells, horizontal cells and retinal ganglion cells before post-natal day 5 (P5).

Translation initiation and assembly of peripherin in cultured cells.

The peripherin gene has three potential ATG translation initiation sites at positions 38, 56, and 290. The second ATG has been proposed to be the initiation codon used for translation of the protein, but there is no experimental evidence for this conjecture. We have isolated a full-length peripherin cDNA (designated as p61-11) from a rat brain cDNA library.

The structure, biochemistry, and metabolism of osteoarthritic cartilage: a review of the literature.

To understand the possible significance of the presence of proteases, cytokines, growth factors, and arachidonic acid metabolites in the osteoarthritic temporomandibular joint (TMJ), the pathogenesis of TMJ osteoarthritis (OA) is discussed, based on knowledge of structure, biochemistry and metabolism of osteoarthritic cartilage in general, and a classification of TMJ OA is presented.

Normal cartilage structure, biochemistry, and metabolism: a review of the literature.

To understand the possible significance of the presence of proteases, cytokines, growth factors, and arachidonic acid metabolites in the osteoarthritic temporomandibular joint (TMJ), a review of the normal physiologic processes and participating factors in the normal TMJ is established, based on knowledge of structure, biochemistry and metabolism of normal cartilage in general.

Calcium pyrophosphate dihydrate crystal deposition disease: a review of the literature and a light and electron microscopic study of a case of the temporomandibular joint with numerous intracellular crystals in the chondrocytes.

The pathogenesis of calcium pyrophosphate dihydrate (CPPD) crystal deposition disease of synovial joints is still unclear, although overproduction of extracellular pyrophosphate (PPi) is thought to play a key role. We studied the light and electron microscopic appearances of a case of CPPD crystal deposition disease of the temporomandibular joint (TMJ) in search of new clues for its pathogenesis. Light microscopic examination of CPPD-containing material from the joint space revealed cartilaginous nodules with various degrees of crystallization.

Activation of the alpha-internexin promoter by the Brn-3a transcription factor is dependent on the N-terminal region of the protein.

The Brn-3a, Brn-3b, and Brn-3c proteins are closely related POU (Pit-Oct-Unc) family transcription factors which are expressed predominantly in neuronal cells. We have identified the alpha-internexin gene as the first reported, neuronally expressed, target gene whose promoter activity is modulated by these factors. Both the Brn-3a and Brn-3c factors can activate the alpha-internexin promoter while Brn-3b represses it and can prevent activation by Brn-3a.

Characterization of the mouse gene encoding the neuronal intermediate filament protein alpha-internexin.

We have determined the complete nucleotide (nt) sequence of the coding region of the mouse gene encoding the neuronal intermediate filament protein, alpha-internexin (alpha INX). The mouse alpha INX gene (m alpha INX) contains three exons and two introns, and may be classified as a member of the type-IV intermediate filament multigene family. The nt sequence of the transcribed region of m alpha INX shows high homology to that of the rat gene.

Reexpression of glial fibrillary acidic protein rescues the ability of astrocytoma cells to form processes in response to neurons.

Astroglial cells play an important role in orchestrating the migration and positioning of neurons during central nervous system development. Primary astroglia, as well as astrocytoma cells will extend long stable processes when co-cultured with granule neurons. In order to determine the function of the glial fibrillary acidic protein (GFAP), the major intermediate filament protein in astroglia and astrocytoma cells, we suppressed the expression of GFAP by stable transfection of an anti-sense GFAP construct in human astrocytoma U251MG cells.

The endless story of the glial fibrillary acidic protein.

All intermediate filament proteins consist of an alpha-helical rod domain flanked by non-helical N-terminal head and C-terminal tail domains. The roles of the non-helical domains of various intermediate filament proteins in the assembly and co-assembly of higher-order filamentous structures have been studied by many groups but with quite contradictory results. Type III intermediate filaments are unique in that they can form homopolymers both in vitro and in vivo.

Expression of the gene for the neuronal intermediate filament protein alpha-internexin coincides with the onset of neuronal differentiation in the developing rat nervous system.

While neurofilaments have long been considered early markers of neuronal differentiation, they cannot be detected in most newly postmitotic neurons of the developing central nervous system (CNS). Here we show that these neurons already express the neuronal intermediate filament protein alpha-internexin at high levels. alpha-internexin is expressed by most, if not all, neurons as they begin differentiation and shows no overlap with vimentin, whose expression in the CNS is restricted to mitotic neuronal precursors.

Outstations of the Golgi complex are present in the processes of cultured rat oligodendrocytes.

Primary cultures of rat oligodendrocytes were incubated with a fluorescent sphingolipid precursor, 6-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]hexanoylceramide+ ++ (C6-NBD-ceramide). This compound is known to stain the Golgi complex specifically. Within 30 min of incubation at 37 degrees C most of the C6-NBD-ceramide was incorporated into the perinuclear Golgi system, as revealed by conventional and confocal laser fluorescence microscopy.

Assembly of type IV neuronal intermediate filaments in nonneuronal cells in the absence of preexisting cytoplasmic intermediate filaments.

We report here on the in vivo assembly of alpha-internexin, a type IV neuronal intermediate filament protein, in transfected cultured cells, comparing its assembly properties with those of the neurofilament triplet proteins (NF-L, NF-M, and NF-H). Like the neurofilament triplet proteins, alpha-internexin coassembles with vimentin into filaments. To study the assembly characteristics of these proteins in the absence of a preexisting filament network, transient transfection experiments were performed with a non-neuronal cell line lacking cytoplasmic intermediate filaments.

Expression of high molecular weight tau in the central and peripheral nervous systems.

Using a novel PCR approach, we have cloned a cDNA encoding the entire high molecular weight tau molecule from rat dorsal root ganglia. The resulting 2080 bp cDNA differs from low molecular weight rat brain tau by the insertion of a novel 762 bp region (exon 4a) between exons 4 and 5. This cDNA clone is identical in sequence with a high molecular weight tau (HMW) cDNA from rat PC12 tumor cells and is closely related to a HMW tau cDNA from mouse N115 tumor cells.

Survival and neurite formation of mesencephalic trigeminal neurones of the rat in vitro.

In order to study the development and functional properties of single, isolated, rat mesencephalic trigeminal neurones, a cell-culture procedure was developed for these specific primary sensory neurones. Mesencephalic trigeminal neurones were isolated from the brainstem of 16-day-old rat embryos. Various factors thought to promote the survival and growth of these neurones in vitro were examined.

Molecular biology of neuronal intermediate filaments.

In the past few years, several neuronal intermediate filament proteins have been characterized. While ongoing investigations have continued to shed light on their developmental expression, the importance of different domains of the proteins for assembly, the elements in their genes necessary for tissue-specific expression, and the role of phosphorylation of neurofilaments, the function(s) of these structures remain a matter of speculation.

Serotonin-immunoreactive terminals in the mesencephalic trigeminal nucleus of the rat: an electron microscopic immunocytochemical study.

The morphological characteristics and distribution of serotonin-immunoreactive terminals within the rat mesencephalic trigeminal nucleus (Me5) were studied using immunocytochemical electron microscopy. Fibers, immunostained by specific antibodies raised against serotonin, were distributed throughout the entire rostrocaudal portion of the Me5. Examination of 355 serotonergic terminals in the caudal part of the Me5 revealed that 93% formed synaptic contacts with dendritic shafts: 68% on small (< 1.

Primary structure of high molecular weight tau present in the peripheral nervous system.

The tau proteins are a family of brain microtubule binding proteins that are required during axonal outgrowth and are found in neurofibrillary tangles in Alzheimer disease. A protein of higher molecular weight, immunologically related to tau, is expressed in the adult peripheral system and in cultured neuronal cell lines of neural crest origin. The predicted amino acid sequence of the high molecular weight tau from N115 cells has been determined from the sequence of its 2340-base-pair cDNA.

Distribution of synaptic boutons in the mesencephalic trigeminal nucleus of the rat--a quantitative electron-microscopical study.

The distribution of synapses and synaptic bouton types in the mesencephalic trigeminal (Me5) nucleus was examined in a quantitative electron-microscopical study. Of 588 terminal boutons that were counted in the compact caudal part of the Me5 nucleus, less than 8% formed synapses on the somata of the predominantly unipolar Me5 neurons. About 79% formed synapses on fibres located between the Me5 somata, while about 13% of the vesicle-containing terminals had no clear synaptic specialization.

Characterization of a panel of neurofilament antibodies recognizing N-terminal epitopes.

Peptides corresponding to sequences from the amino-terminal "head" regions of the low, middle, and high molecular weight neurofilament proteins (NF-L, NF-M, and NF-H) were synthesized by a modification of the Merrifield solid-phase method, and a panel of polyclonal antibodies to these epitopes were prepared in rabbits by the injection of synthetic peptides conjugated to the carrier protein keyhole limpet hemocyanin (KLH). An additional, monoclonal antibody recognizing both glial fibrillary acidic protein (GFAP) and vimentin was also produced, by fusion of cells of the mouse myeloma line NS-1 with spleen cells from a mouse immunized with cytoskeletal extracts. Antibody specificities were confirmed by a combination of Western blotting against cytoskeletal extracts and immunofluorescence using both rat brain sections and fibroblasts transfected with fully encoding cDNAs for each neurofilament protein, driven by viral promoters.

Structure of the gene for the neuronal intermediate filament protein alpha-internexin and functional analysis of its promoter.

We have isolated the gene encoding the neuronal intermediate filament protein alpha-internexin using low stringency hybridization conditions and an NF-M (neurofilament middle molecular weight subunit) cDNA probe. This gene consists of three exons and two introns. The sequence data and the exon-intron organization of the gene establish its classification as a type IV intermediate filament gene.

High molecular weight tau: preferential localization in the peripheral nervous system.

Using epitope mapping we have demonstrated that a high molecular weight protein (Mr approximately 115 x 10(3)) present in brain and spinal cord is a member of the tau family of microtubule-associated proteins. Antibodies directed against the amino-terminal, middle and carboxyl-terminal portions of tau recognize this protein. A limited survey of neuronal tissues has shown that this high molecular weight tau protein is present in brain, spinal cord, dorsal root ganglia, dorsal and ventral roots and peripheral nerves.

Expression of alpha B-crystallin in the developing rat kidney.

The expression and cellular localization of alpha B-crystallin during rat renal development was studied by Northern blot analysis and by immunocytochemistry. Northern blotting of total RNA extracted from whole kidneys revealed that the messenger RNA for alpha B-crystallin rapidly increased after birth to reach adult levels by 20 days. At the same time, immunohistochemistry for alpha B-crystallin demonstrated that the prominent elongation of Henle's loop during the first 10 days of life was accompanied by increased alpha B-crystallin expression.

Isolation and characterization of the rat chromosomal gene for a polypeptide (pS1) antigenically related to statin.

Increasing evidence shows the existence of nonproliferation-specific gene(s) whose expression is mostly present in growth-arrested cells. One member of this gene family has been identified by previous work as a nuclear protein of 57,000 Da, termed statin. Logical extensions of statin research are to identify the genomic and cDNA clones encoding for statin and to study the regulation of statin gene expression.

Effects of truncated neurofilament proteins on the endogenous intermediate filaments in transfected fibroblasts.

The expression and assembly characteristics of carboxyl- and amino-terminal deletion mutants of rat neurofilament low Mr (NF-L) and neurofilament middle Mr (NF-M) proteins were examined by transient transfection of cultured fibroblasts. Deletion of the carboxyl-terminal tail domain of either protein indicated that this region was not absolutely essential for co-assembly into the endogenous vimentin cytoskeleton. However, deletion into the alpha-helical rod domain resulted in an inability of the mutant proteins to co-assemble with vimentin into filamentous structures.