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At least 289 records · Page 16Linked to original sources
PubMed2004

Delayed expression of the Crx gene and photoreceptor development in the Chx10-deficient retina.

PURPOSE: The Chx10 homeobox gene is expressed in neural progenitor cells during retinal development. The absence of Chx10 causes microphthalmia in humans and in the mouse mutant ocular retardation. The purpose of this study was to examine how neuronal development is affected by absence of the Chx10 transcription factor in the mouse retina. METHODS: Expression of transcription factor genes, Crx, Pou4f2, and Pax6, that mark specific cell types as they begin to differentiate was analyzed by RNA in situ hybridization of retina from wild-type and Chx10-null ocular retardation mice (Chx10(or-J/or-J)). RT-PCR analysis was used to compare expression of these genes and putative targets of Crx regulation. Photoreceptor development was analyzed by using peanut agglutinin (PNA)-rhodamine and blue cone opsin antibody to label cones and rhodopsin antibody to label rods. RESULTS: The photoreceptor gene Crx, normally expressed during embryonic retinal development, was not detected in the embryonic mutant retina, but was expressed after birth. Expression of the targets of Crx regulation, rhodopsin, peripherin, rod phosphodiesterase beta (Pdeb), and arrestin, with the exception of interphotoreceptor retinoid binding protein (Irbp), was delayed in the Chx10(or-J/or-J) retina. Rhodopsin localization in rod outer segments was also delayed. By contrast, temporal and spatial expression of Pou4f2 and Pax6 in developing ganglion and amacrine cells and PNA and blue opsin in developing cone cells was relatively normal in the mutant. CONCLUSIONS: Delay of the normal temporal expression of genes essential for photoreceptor disc morphogenesis leads to failure of correct rod and cone outer segment formation in the Chx10(or-J/or-J) mutant retina. In addition, the absence of Chx10 appears to affect the development of late-born cells more than that of early-born cells, in that a low number of rods develops, whereas formation of ganglion, amacrine, and cone cells is relatively unaffected.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed2006

Investigation of general and cytoskeletal markers to estimate numbers and proportions of neurons in the human intestine.

An important requirement in pathological diagnostics in the human enteric nervous system (ENS) is the estimation of the total numbers of neurons and of proportions of distinct subpopulations. In this study, we compared the suitability of two suggested panneuronal markers, cuprolinic blue (CB) and anti-Hu-protein (HU), for staining and counting human myenteric neurons in wholemounts, derived from small and large intestinal samples. Furthermore, the proportional expression of three cytoskeletal intermediate filaments, alpha-internexin (IN), neurofilament 200 (NF) and peripherin (PE), was correlated with both CB and HU. In 8 CB- and HU-stained wholemounts, 93.3% of all neurons were double labeled, 3.3% of neurons were stained only with CB whereas 3.3% were immuno-stained only for HU. Thus, both markers were comparably reliable in representing the putative total human myenteric neuron population in our material. The wholemounts double stained for IN/CB or IN/HU revealed between 56.2 and 71.5% of neurons to be IN-reactive. Between 42.8 and 50.9% of neurons were immunoreactive for NF whereas 53.9 to 62.4% of neurons were reactive for PE. Although our sample number was too small to allow final conclusions, we suggest that the variations in proportions of intermediate filament expression we observed may be due to individual circumstances rather than to correlation with age or region. The proportions of neurons positive for IN, NF or PE but unstained by CB histochemical or HU immunohistochemical techniques was between 0 and 2.2%. We conclude that both CB and HU techniques are suitable methods for representation of almost all myenteric neurons in the human gut and that the differential expression of the cytoskeletal proteins investigated has to be included in the classification of enteric neurons in pathological diagnostics of human gastrointestinal diseases.

Adolescent↗
PubMed1999

Lactose promotes organized photoreceptor outer segment assembly and preserves expression of photoreceptor proteins in retinal degeneration.

PURPOSE: We have previously shown that lactose promotes the proper assembly of photoreceptor outer segments in the absence of the retinal pigment epithelium (RPE). The purpose of this study was to determine if the difference between organized and disorganized membranes was a variation in the amounts of two structural proteins, opsin and rds/peripherin. METHODS: Eye rudiments were dissected from Xenopus laevis embryos and the RPE was removed prior to culturing in the following media: Niu-Twitty medium; Niu-Twitty with mannose; Niu-Twitty with lactose. Controls included retinas that matured in vitro with an adherent RPE. Photoreceptor ultrastructure was evaluated with emphasis on outer segment membrane organization. The relative amounts of opsin and rds/ peripherin, two outer segment-specific proteins, were determined, as were their immunolabeling patterns. RESULTS: In control retinas, outer segments were composed of stacked, flattened membranous saccules. Opsin labeling of rod outer segments was very dense, indicative of normally organized disc membranes, and rds/peripherin labeling was heavy at the outer segment disc periphery and incisures. In the absence of the RPE, a whorl-like profile of outer segments is present in what would be the sub-retinal space. Opsin immunolabeling was patchy and disorganized. Immunolabeling of rds/peripherin was present, but in a disorderly array. Mannose showed no protective effect. In contrast, lactose promoted the formation of organized outer segments and allowed for near normal expression of both photoreceptor markers. In retinas with disorganized outer segments, the expression of opsin is downregulated while the expression of rds/peripherin is maintained or upregulated. CONCLUSIONS: Lactose protects against the retinal degeneration induced by RPE removal by preserving the outer segment structure and the photoreceptor immunolabeling patterns. It also maintains constant the relative amounts of opsin and rds/peripherin. It is possible that in degenerating retinas, photoreceptors upregulate rds/peripherin expression in attempt to provide additional support for the proper folding of nascent membranes, however this is insufficient to permit organization of the photoreceptor outer segments. Our results suggest that rescue-effect of lactose is mediated by a non-rds/peripherin related mechanism.

Animals↗
PubMed2002

[Genetic and molecular characterization of 148 patients with autosomal dominant retinitis pigmentosa (ADRP)].

OBJECTIVE: Genetic characterization of a series of patients with autosomal dominant retinitis pigmentosa (ADRP). METHODS: All patients underwent complete ophthalmological examination including computerized perimetry, electroretinography and occasionally fluorescein angiography. Blood samples were drawn for genetic analysis of candidate genes namely rhodopsin (RHO), peripherin-RDS, ROM-1, CRX, RP1 and NRL. RESULTS: 148 ADRP index cases were examined at our hospital from June 1991 to September 2001. Genetic analysis detected the following mutations: 29 different families (19.5%) carried a RHO mutation among which the Pro-347-Leu was the most frequent one, five different RP-1 mutations (3.3%), 2 RDS mutations and one NRL mutation, which is the second reported in the world literature. CONCLUSIONS: RHO followed by RP1 are the most frequent ADRP-causing genes in our series as in other published ones, and RDS causes mainly macular dystrophies. Molecular characterization was possible in 37 families (25%) which is of great interest for visual prognosis and genetic counselling.

Amino Acid Substitution↗
PubMed2003

[Cloning of a DnaJ homolog chaperon PBP and its subcellular localization].

AIM: To isolate and identify a human DnaJ homolog chaperon, PBP, from a human skeleton cDNA library, and to analyze its expression and distribution in transfected mammalian cells. METHODS: (32)p-dCTP labeled probe hybridization was used to screen the human skeleton cDNA library and sequence of the positive clones were analyzed. Then PBP gene was transfected into COS-7 cells using lipofectamin. PBP expressed in the cells were detected by Western-blot and indirect immunofluorescence staining. RESULTS: A full-length(1.5 kb) cDNA of peripherin-binding protein (PBP) was identified, which is identical with that of mrj. Full length PBP was mainly localized to cytoplasms of COS-7 cells in interphase, and to nuclei in mitosis. CONCLUSION: The results indicate that besides cooperating with DnaK (HSP70), PBP itself plays an important role as a member of DnaJ family. PBP may also be involved in the regulation of cell cycle.

Amino Acid Sequence↗
PubMed1989

Nuclear antigens in neoplastic lymphocytes of B cell and T cell non-Hodgkin's lymphomas.

Gross nuclear morphology is a major diagnostic feature in the identification of subtypes of non-Hodgkin's lymphoma (NHL). The authors have shown that the size, shape, and chromatin distribution of the lymphocyte nuclei vary extensively both within and between samples of a subtype, and have proposed that the variations may reflect qualitative and quantitative differences in extrachromatinic components. To test this hypothesis, the organization of individual nuclear antigens in NHL and in reactive hyperplasia biopsies was examined by immunofluorescence labeling of frozen sections with previously characterized monoclonal antibodies. The results have been correlated with observations of the staining patterns produced by the antibodies in mitogenically stimulated human peripheral blood lymphocytes. Labeling pattern and intensity with each antibody were consistent between preparations of blood lymphocytes, and all four antibodies labeled all blood lymphocyte samples tested. In contrast, only 15% of the 53 biopsies were labeled by all four antibodies, although all were stained by anti-peripherin, nearly 80% by I1, and almost 60% by PI1. Antibody PI2 labeling was detected in only 20% of the samples. Variation in labeling intensity was equally extensive both within and between biopsy samples. In general, there was little homogeneity between samples of an NHL subtype as to which antigens were detected, their labeling intensity, or their pattern of intranuclear distribution. These observations are consistent with earlier reports of significant diversity in the morphology of nonchromatin components in such samples. The data support the proposition that the heterogeneity of gross nuclear morphology in nuclei of NHL biopsies may be due in part to disordered expression or abnormal organization of nuclear proteins.

Antibodies↗
PubMed1993

Surface and cytoskeletal markers of rostrocaudal position in the mammalian nervous system.

To identify cell surface molecules that define position in the mammalian nervous system, we previously characterized the binding of two monoclonal antibodies, ROCA1 and ROCA2, to adult rat sympathetic ganglia and intercostal nerves. The binding of ROCA1 is highest in rostral ganglia and nerves and declines in a graded manner in the caudal segments. ROCA2 labels the same cells in ganglia and nerves as ROCA1, but not in a position-selective manner. We now show by immunoblot analysis that ROCA1 recognizes two antigens in membrane/cytoskeletal fractions of peripheral nerves and ganglia: (1) a Triton X-100-insoluble, 60 kDa protein and (2) a Triton x-100-insoluble, 26 kDa protein. The 60 kDa protein is expressed at higher levels in rostral than in caudal intercostal nerves, and is identified as the intermediate filament protein peripherin. In contrast, it is the ROCA1 epitope on the 26 kDa protein, and not the protein itself, that is preferentially visualized immunohistochemically in rostral nerves and ganglia. We suggest that the ROCA1 epitope on the 26 kDa protein is masked in sections of caudal nerves and ganglia. Amino acid sequence data obtained from the affinity-purified 26 kDa protein indicate significant homology with human CD9, a cell surface protein implicated in intercellular signaling in hematopoietic cells. These results suggest that intermediate filament gene expression and epitope masking on the cell surface may be involved in functions related to position in the nervous system.

Amino Acid Sequence↗
PubMed1993

[Molecular cloning of the genes in genetic chorioretinal diseases--positional cloning and the candidate gene approach].

Two different molecular biological approaches to the disease-causing genes of genetic eye diseases are described. In gyrate atrophy of the chroid and retina where the biochemical defect was identified as inactivation of ornithine aminotransferase, the gene was cloned by using antibody for the enzyme. In most genetic eye diseases, however, the biochemical defects are unknown. Positional cloning and/or the candidate gene approach are used to identify the disease-causing genes for these diseases. The genes of chroideremia and Norrie disease were cloned by positional cloning. Several genes expressed in the photoreceptor cells have been identified recently and may be the genes causing progressive degeneration of the retina and choroid. Rhodopsin, peripherin (RDS), rom-1, and beta subunit-cGMP phosphodiesterase are identified as the disease-causing genes for retinitis pigmentosa by the candidate gene approach.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1998

GABA inhibits migration of luteinizing hormone-releasing hormone neurons in embryonic olfactory explants.

During development, a subpopulation of olfactory neurons transiently expresses GABA. The spatiotemporal pattern of GABAergic expression coincides with migration of luteinizing hormone-releasing hormone (LHRH) neurons from the olfactory pit to the CNS. In this investigation, we evaluated the role of GABAergic input on LHRH neuronal migration using olfactory explants, previously shown to exhibit outgrowth of olfactory axons, migration of LHRH neurons in association with a subset of these axons, and the presence of the olfactory-derived GABAergic neuronal population. GABAA receptor antagonists bicuculline (10(-5) M) or picrotoxin (10(-4) M) had no effect on the length of peripherin-immunoreactive olfactory fibers or LHRH cell number. However, LHRH cell migration, as determined by the distance immunopositive cells migrated from olfactory pits, was significantly increased by these perturbations. Addition of tetrodotoxin (10(-6) M), to inhibit Na+-transduced electrical activity, also significantly enhanced LHRH migration. The most robust effect observed was dramatic inhibition of LHRH cell migration in explants cultured in the presence of the GABAA receptor agonist muscimol (10(-4) M). This study demonstrates that GABAergic activity in nasal regions can have profound effects on migration of LHRH neurons and suggests that GABA participates in appropriate timing of LHRH neuronal migration into the developing brain.

Animals↗
PubMed1998

Altered expression of helix-loop-helix transcriptional regulators and cyclin D1 in Wnt-1-transformed PC12 cells.

Nerve growth factor induces PC12 cells to differentiate from a chromaffin cell to a sympathetic neuronal phenotype. In contrast, PC12 cells, which stably express Wnt-1, a secreted signaling factor required for development of mammalian midbrain and cerebellum, fail to express differentiation-specific genes in response to nerve growth factor. Analysis of factors binding to E box-containing regulatory elements of the terminal differentiation gene encoding peripherin suggested a differentiation-specific control of expression of helix-loop-helix transcriptional regulators. Specifically, the MASH-1 (mammalian achaete-scute homologue) helix-loop-helix transcription factor, which plays a positive role in neuronal differentiation, is reduced in Wnt-1/PC12 cells, and HES-1, a negative regulator of MASH-1, is increased. These data suggest that the differentiation block may result from induction of HES-1. Wnt-1/PC12 cells also proliferate more rapidly and express increased levels of cyclin D1. Thus, Wnt-1 may block the differentiation and enhance the proliferation of PC12 cells by activating HES-1 and cyclin D1 and repressing MASH-1.

Animals↗
PubMed1997

Comprehensive immunofluorescence and lectin binding analysis of intervibrissal fur innervation in the mystacial pad of the rat.

The innervation of the intervibrissal fur in the mystacial pad of the rat and mouse was examined by immunofluorescence with a wide variety of antibodies for neuronal related structural proteins, enzymes, and peptides as well as for lectin binding histofluorescence with Griffonia simplicifolia (GSA). Anti-protein gene product 9.5 (PGP) immunofluorescence labeled all sets of axons and endings. The innervation in the upper dermis and epidermis was distributed through a four tiered dermal plexus. From deep to superficial, the second tier was the source of all apparent myelinated mechanoreceptors, the third tier of nearly all the peptidergic and GSA binding innervation, and the fourth tier of nonpeptidergic GSA negative innervation (peptide-/GSA-). Three types of mechanoreceptors-Merkel, transverse lanceolate, and longitudinal lanceolate endings-innervated guard hair follicles. All had similar labeling characteristics for 160 kDa and 200 kDa neurofilament subunits, peripherin, carbonic anhydrase, synaptophysin, and S100. Palisades of longitudinal lanceolate endings were part of piloneural complexes along circumferentially oriented sets of transverse lanceolate endings, peptidergic free nerve endings (FNEs), and peptide-/GSA- FNEs. The longitudinal lanceolate endings were the only mechanoreceptors in the mystacial pad that had detectable calcitonin gene-related peptide. The epidermis contained four types of unmyelinated endings: simple free nerve endings (FNEs), penicillate endings, cluster endings and bush endings. Only the simple FNEs were clearly peptidergic. Virtually all others were peptide-/ GSA-. Each bush ending was actually an intermingled cluster of endings formed by several unmyelinated axons and occasionally an Adelta axon. In contrast to the other unmyelinated innervation to the epidermis, bush endings labeled with an antibody against the Schwann cell protein S100. The necks and mouths of follicles, as well as superficial vasculature, were innervated by a mixture of unmyelinated peptidergic and/or GSA labeled sensory and sympathetic axons. Small presumptive sweat glands were innervated by three sets of peptidergic axons of which one was immunoreactive for somatostatin. Potential functions of the various sets of innervation are discussed.

Animals↗
PubMed1996

Mutagenesis of ser41 to ala inhibits the association of GAP-43 with the membrane skeleton of GAP-43-deficient PC12B cells: effects on cell adhesion and the composition of neurite cytoskeleton and membrane.

To investigate the molecular basis for GAP-43 function in axon outgrowth, we produced a mutant, GAP-43 (Ala41), whose interaction with calmodulin in vitro was unaffected by increasing Ca2+ concentrations, and stably transfected it into GAP-43-deficient PC12B cells. Several lines that expressed wild-type or mutant protein at levels that resembled endogenous GAP-43 expression in PC12 controls were subcloned and characterized. GAP-43 (Ala41) was significantly more extractable with Nonidet P-40 and less tightly associated with the membrane skeleton than the wild-type protein. Furthermore, GAP-43 (Ala41) expression by PC12B cells profoundly affected their phenotype: First, observation of living cells using video-enhanced microscopy revealed irregular plasma membranes with numerous blebs and protrusions and neurites that appeared thin and varicose. Second, both the cells' ability to remain attached to laminin substrates and the amount of alpha 1 beta 1 integrin expressed on the cell surface was significantly decreased. Finally, peripherin transport, which is abnormal in PC12B cells, could be rescued by transfection of wild-type GAP-43 but not the GAP-43 (Ala41) mutant. The phenotypic abnormalities resemble other cell types in which membrane skeleton/plasma membrane interactions have been functionally decoupled, and our results are consistent with the notion that these interactions may be abnormal in GAP-43 (Ala41)-expressing PC12B cells, either as a direct consequence of the mutation or arising secondarily to the altered availability of calmodulin in the growing neurite.

Alanine↗
PubMed1994

Autosomal-dominant cerebellar ataxia with retinal degeneration (ADCA type II) is genetically different from ADCA type I.

Autosomal-dominant cerebellar ataxia (ADCA) type II is a neurodegenerative disorder presenting with cerebellar ataxia and retinal degeneration. We analyzed the clinical features of 21 patients with ADCA type II from 3 Moroccan and 2 French families. Mean age at onset was 17 years earlier in offspring than in their parents, compatible with anticipation. There was a suggestion of imprinting, with predominantly paternal transmission of early onset and severe forms of the affection. Candidate genes were tested in the family with the largest pedigree. The two known loci for ADCA type I (spinal cerebellar ataxia 1 and 2) were excluded, as were candidate loci, retinitis pigmentosa 1 locus (RP1) and the genes for rhodopsin and peripherin-rds, responsible for autosomal dominant retinitis pigmentosa. ADCA type II does not therefore result from an allelic mutation of the tested genes for ADCA type I or autosomal dominant retinitis pigmentosa.

Adolescent↗
PubMed1994

The chromosome periphery during mitosis.

A complex structure, visible by electron microscopy, surrounds each chromosome during mitosis. The organization of this structure is distinct from that of the chromosomes and the cytoplasm. It forms a perichromosomal layer that can be isolated together with the chromosomes. This layer covers the chromosomes except in centromeric regions. The perichromosomal layer includes nuclear and nucleolar proteins as well as ribonucleoproteins (RNPs). The list of proteins and RNAs identified includes nuclear matrix proteins (perichromin, peripherin), nucleolar proteins (perichro-monucleolin, Ki-67 antigen, B23 protein, fibrillarin, p103, p52), ribosomal proteins (S1) and snRNAs (U3 RNAs). Only limited information is available about how and when the perichromosomal layer is formed. During early prophase, the proteins extend from the nucleoli towards the periphery of the nucleus. Thin cordon-like structures reach the nuclear envelope delimiting areas in which chromosomes condense. At telophase, the proteins are associated with the part of the chromosomes remaining condensed and accumulate in newly formed nucleoli in regions where chromatin is already decondensed. The perichromosomal layer contains several different classes of proteins and RNPs and it has been attributed various roles: (1) in chromosome organization, (2) as a barrier around the chromosomes, (3) involvement in compartmentation of the cells in prophase and telophase and (4) a binding site for chromosomal passenger proteins necessary to the early process of nuclear assembly.

Animals↗
PubMed1991

Arrestin mRNA expression, biosynthesis, and localization in degenerating photoreceptors of mutant rds mice retinas.

The retinal photoreceptors of the mutant rds mouse are unable to form normal outer segments. Eventually the abnormal cells die in the months following birth. The genetic defect in the rds mouse was recently localized to the peripherin gene that encodes a protein in the outer segment disc margin. Although this mutation may explain the morphogenetic defect, i.e., the failure to form outer segments, the reason for subsequent cell death is not clear. Previously, we demonstrated that the capability to synthesize opsin, an outer segment integral membrane protein, is not compromised by the morphogenetic defect although the opsin steady-state content is considerably reduced, since it is not incorporated into an organized outer segment. We have now studied arrestin, a cytoplasmic protein that is part of the phototransduction cascade and appears to shuttle between the inner and outer segment during the light/dark cycle. Since rds mice lack outer segments, it was of interest to determine the effects of the photoreceptor abnormality on arrestin gene expression. Arrestin mRNA levels and protein synthetic rates were high in young rds retinas. When corrected for cell loss, the steady-state arrestin content per cell in the rds retina was comparable to normal. However, in the absence of an outer segment, the total amount of arrestin is concentrated in the remaining inner segment. Consequently, a relatively high level of arrestin is present in the rds inner segment throughout the light/dark cycle. We suggest that the morphogenetic defect indirectly precipitates secondary effects such as the persistent presence of high levels of arrestin or other soluble proteins in the abnormal photoreceptor inner segment, nucleus, and synaptic terminal. This condition, if toxic to the cells, may compromise photoreceptor viability in the rds retina.

Animals↗
PubMed1995

Presence or absence of TrkA protein distinguishes subsets of small sensory neurons with unique cytochemical characteristics and dorsal horn projections.

Investigations into the biological actions of nerve growth factor (NGF) have shown that dorsal root ganglion (DRG) neurons subserving nociception require NGF for survival and maintenance of phenotype. This discovery suggests that the signaling NGF receptor, TrkA, can be used as a marker for nociceptive neurons. In this study, we have used antibodies to TrkA, in conjunction with cell biological markers that show a restricted distribution in the DRG, to further characterize subsets of DRG neurons that are dependent upon NGF. Staining for TrkA labeled small and medium-sized neurons that composed 47% of all neurons in thoracic ganglia. Double-labeling with antibodies to the high molecular weight neurofilament protein (NFH), a marker for neurons with myelinated axons, demonstrated that TrkA staining is found in only a small subset of myelinated neurons. Surprisingly, many DRG neurons were not labeled by either TrkA or NFH. These neurons had small soma areas, contained the intermediate filament protein peripherin, and were labeled by the lectin BSI, identifying them as neurons likely to have unmyelinated axons. In addition, small TrkA-negative neurons were extensively labeled by antibodies to the intermediate filament protein alpha-internexin, the delta isoform of protein kinase C, and by the BSI isolectin BSI-B4. In order to assess the potential functions of TrkA-negative small neurons, we examined their projections to the dorsal horn of the spinal cord. TrkA-immunoreactivity in the spinal cord was restricted to lamina I and the outer region of lamina II (IIo), similar to staining for calcitonin gene-related peptide. In contrast, the central projections of TrkA-negative neurons, as visualized by BSI-B4 staining, were particularly dense in lamina IIi. Our results suggest that TrkA-expressing and non-TrkA-expressing small neurons compose functionally distinct populations of DRG neurons.

Animals↗
PubMed2005

Nestin-expressing neural stem cells identified in the scar following myocardial infarction.

Nerve fiber innervation of the scar following myocardial damage may have occurred either via the growth of pre-existing fibers and/or the mobilization of neural stem cells. The present study examined whether neural stem cells were recruited to the infarct region of the rat heart following coronary artery ligation. The neural stem cell marker nestin was detected in the infarct region of 1-week post-myocardial infarct (MI) male rats and cultured scar-derived neural-like cells. By contrast, nestin staining was undetected in either scar myofibroblasts or cardiac myocytes residing in the non-infarcted left ventricle. Reactive astrocytes were isolated from the infarct region and characterized by the co-expression of nestin, glial fibrillary acidic protein, and vimentin. Specific staining of oligodendrocytes and neurons was also detected in the infarct region and cultured scar-derived neural-like cells. Furthermore, neurofilament-M positive fibers were identified in the scar and tyrosine hydroxylase immunoreactivity was observed in peripherin-positive neurons. Neurite formation was induced in PC12 cells treated with the conditioned-media of primary passage scar-derived cells, highlighting the synthesis and secretion of neurotrophic factors. Nerve growth factor (NGF) and brain-derived neurotrophic factor were detected in myofibroblasts and neural cells, and both cell types expressed the NGF receptors trkA and p75. These data highlight the novel observation that neural stem cells were recruited to the infarct region of the damaged rat heart and may contribute in part to nerve fiber growth and subsequent innervation of the scar.

Animals↗
PubMed2005

Overexpression of neuronal intermediate filament protein alpha-internexin in PC12 cells.

The neuronal intermediate filaments include not only the neurofilament triplet proteins but also peripherin and alpha-internexin. To determine whether neurite outgrowth is enhanced by alpha-internexin, the cDNA of rat alpha-internexin tagged with enhanced green fluorescent protein (EGFP) was transfected into a rat adrenal pheochromocytoma cell line PC12 that responds to nerve growth factor (NGF) by induction of the neuronal phenotype. Selected stable clones were induced by NGF and examined for expression patterns of neuronal intermediate filaments by Western blot and immunocytochemistry. Differentiating neurons were also collected after NGF induction for RT-PCR analysis. Overexpressed alpha-internexin-EGFPs were found mainly in cell bodies and the proximal part of neurites. It was also found that overexpression of alpha-internexin-EGFPs enhanced the neurite outgrowth of PC12 cells at the early stages of NGF induction. Meantime, NF-L and NF-M were upregulated by the overexpression of alpha-internexin-EGFPs. Interestingly, alpha-internexin-EGFP-transfected cells obviously detached from culture plates at the later stages of NGF induction. Massive IF accumulations, swelling mitochondria, and degenerating neurites with numerous electron-dense granules were observed ultrastructurally in the alpha-internexin-EGFP-transfected cells. In addition, neuronal death was also characterized positively by the TUNEL assay. These observations may imply that cell death was occurring in alpha-internexin-EGFP-transfected cells. From this study, it could be suggested that alpha-internexin plays an important role in neurite outgrowth and regulates the expression of other neurofilaments during neuronal development. Apoptosis-like cell death could also be induced by the overexpression of alpha-internexin-EGFP in PC12 cells after NGF induction.

Animals↗