Biomedical subjects

A Mizoguchi

Publications and source records attributed to A Mizoguchi.

At least 91 records · Page 5Linked to original sources

PubMed1997

Suppressive role of B cells in chronic colitis of T cell receptor alpha mutant mice.

The role of antibodies (Abs) in the development of chronic colitis in T cell receptor (TCR)-alpha-/- mice was explored by creating double mutant mice (TCR-alpha-/- x immunoglobulin (Ig)mu-/-), which lack B cells. TCR-alpha-/- x Ig mu-/- mice spontaneously developed colitis at an earlier age, and the colitis was more severe than in TCR-alpha-/- mice. Colitis was induced in recombination-activating gene-1 (RAG-1-/-) mice by the transfer of mesenteric lymph node (MLN) cells from TCR-alpha-/- x Ig mu-/- mice. When purified B cells from TCR-alpha-/- mice were mixed with MLN cells before cell transfer, colitis did not develop in RAG-1-/- mice. Administration of the purified Ig from TCR-alpha-/- mice and a mixture of monoclonal autoAbs reactive with colonic epithelial cells led to attenuation of colitis in TCR-alpha-/- x Ig mu-/- mice. Apoptotic cells were increased in the colon, MLN, and spleen of TCR-alpha-/- x Ig mu-/- mice as compared to Ig mu-/- mice and TCR-alpha-/- mice. Administration of the purified Ig from TCR-alpha-/- mice into TCR-alpha-/- x Ig mu-/- mice led to decrease in the number of apoptotic cells. These findings suggest that although B cells are not required for the initiation of colitis, B cells and Igs (autoAbs) can suppress colitis, presumably by affecting the clearance of apoptotic cells.

Adoptive Transfer↗

PubMed1997

The Ras target AF-6 interacts with ZO-1 and serves as a peripheral component of tight junctions in epithelial cells.

The dynamic rearrangement of cell-cell junctions such as tight junctions and adherens junctions is a critical step in various cellular processes, including establishment of epithelial cell polarity and developmental patterning. Tight junctions are mediated by molecules such as occludin and its associated ZO-1 and ZO-2, and adherens junctions are mediated by adhesion molecules such as cadherin and its associated catenins. The transformation of epithelial cells by activated Ras results in the perturbation of cell-cell contacts. We previously identified the ALL-1 fusion partner from chromosome 6 (AF-6) as a Ras target. AF-6 has the PDZ domain, which is thought to localize AF-6 at the specialized sites of plasma membranes such as cell-cell contact sites. We investigated roles of Ras and AF-6 in the regulation of cell-cell contacts and found that AF-6 accumulated at the cell-cell contact sites of polarized MDCKII epithelial cells and had a distribution similar to that of ZO-1 but somewhat different from those of catenins. Immunoelectron microscopy revealed a close association between AF-6 and ZO-1 at the tight junctions of MDCKII cells. Native and recombinant AF-6 interacted with ZO-1 in vitro. ZO-1 interacted with the Ras-binding domain of AF-6, and this interaction was inhibited by activated Ras. AF-6 accumulated with ZO-1 at the cell-cell contact sites in cells lacking tight junctions such as Rat1 fibroblasts and PC12 rat pheochromocytoma cells. The overexpression of activated Ras in Rat1 cells resulted in the perturbation of cell-cell contacts, followed by a decrease of the accumulation of AF-6 and ZO-1 at the cell surface. These results indicate that AF-6 serves as one of the peripheral components of tight junctions in epithelial cells and cell-cell adhesions in nonepithelial cells, and that AF-6 may participate in the regulation of cell-cell contacts, including tight junctions, via direct interaction with ZO-1 downstream of Ras.

Animals↗

PubMed1997

Afadin: A novel actin filament-binding protein with one PDZ domain localized at cadherin-based cell-to-cell adherens junction.

A novel actin filament (F-actin)-binding protein with a molecular mass of approximately 205 kD (p205), which was concentrated at cadherin-based cell-to-cell adherens junction (AJ), was isolated and characterized. p205 was purified from rat brain and its cDNA was cloned from a rat brain cDNA library. p205 was a protein of 1,829 amino acids (aa) with a calculated molecular mass of 207,667 kD. p205 had one F-actin-binding domain at 1,631-1,829 aa residues and one PDZ domain at 1,016- 1,100 aa residues, a domain known to interact with transmembrane proteins. p205 was copurified from rat brain with another protein with a molecular mass of 190 kD (p190). p190 was a protein of 1,663 aa with a calculated molecular mass of 188,971 kD. p190 was a splicing variant of p205 having one PDZ domain at 1,009-1,093 aa residues but lacking the F-actin-binding domain. Homology search analysis revealed that the aa sequence of p190 showed 90% identity over the entire sequence with the product of the AF-6 gene, which was found to be fused to the ALL-1 gene, known to be involved in acute leukemia. p190 is likely to be a rat counterpart of human AF-6 protein. p205 bound along the sides of F-actin but hardly showed the F-actin-cross-linking activity. Northern and Western blot analyses showed that p205 was ubiquitously expressed in all the rat tissues examined, whereas p190 was specifically expressed in brain. Immunofluorescence and immunoelectron microscopic studies revealed that p205 was concentrated at cadherin-based cell-to-cell AJ of various tissues. We named p205 l-afadin (a large splicing variant of AF-6 protein localized at adherens junction) and p190 s-afadin (a small splicing variant of l-afadin). These results suggest that l-afadin serves as a linker of the actin cytoskeleton to the plasma membrane at cell-to-cell AJ.

Actins↗

PubMed1997

Nedd5, a mammalian septin, is a novel cytoskeletal component interacting with actin-based structures.

The mouse Nedd5 gene encodes a 41.5-kD GTPase similar to the Saccharomyces and Drosophila septins essential for cytokinesis. Nedd5 accumulates near the contractile ring from anaphase through telophase, and finally condenses into the midbody. Microinjection of anti-Nedd5 antibody interferes with cytokinesis, giving rise to binucleated cells. In interphase and postmitotic cells, Nedd5 localizes to fibrous or granular structures depending on the growth state of the cell. The Nedd5-containing fibers are disrupted by microinjection of GTPgammaS and by Nedd5 mutants lacking GTP-binding activity, implying that GTP hydrolysis is required for its assembly. The Nedd5-containing fibers also appear to physically contact actin bundles and focal adhesion complexes and are disrupted by cytochalasin D, C3 exoenzyme, and serum starvation, suggesting a functional interaction with the actin-based cytoskeletal systems in interphase cells.

3T3 Cells↗

PubMed1997

Developmental changes in the subcellular localization of R-cadherin in chick retinal pigment epithelium.

It has been reported that in the chick embryonic retina, N-cadherin first appears at the very early stages and is subsequently substituted by R-cadherin at the middle to late stages of development. To examine the role of R-cadherin in the morphogenesis of chick retinal pigment epithelium (RPE), the distribution of this adhesion molecule was studied by immunofluorescence cytochemistry and immunoelectron microscopy from embryonic day (E) 6 to hatching. R-cadherin immunoreactivity was detected at E6, and was strongest at E12-13. During these stages, R-cadherin was expressed uniformly on the lateral plasma membranes of RPE cells in contact with each other. Thereafter, R-cadherin immunoreactivity was markedly decreased, with intense immunoreactivity restricted to zonulae adherentes in latero-apical regions at E16. R-cadherin immunoreactivity was no longer detectable in the newly hatched chick RPE, even though morphologically well developed zonulae adherentes were present in latero-apical regions. No immunoreactivity was detected on the apical side facing the neural retina or on the basal side facing the basal lamina at any stage of development. These findings indicate that R-cadherin plays an important role as a major cadherin subtype in the morphogenesis of chick embryo RPE, and is involved initially in non-specific cell-cell adhesions, and subsequently in the formation and maintenance of developing zonulae adherentes.

Animals↗

PubMed1997

Antineutrophil cytoplasmic antibodies in T-cell receptor alpha-deficient mice with chronic colitis.

BACKGROUND & AIMS: Antineutrophil cytoplasmic antibodies (ANCAs) have been detected in approximately 60% of sera from patients with ulcerative colitis. The aim of this study was to examine the presence of ANCAs and distribution of ANCA-producing B cells in the lymphoid tissue of T-cell receptor alpha-deficient (TCR-alpha-/-) mice that develop chronic colitis resembling human ulcerative colitis. METHODS: Sera from 87 TCR-alpha-/- mice were tested for the presence of ANCAs by enzyme-linked immunosorbent assay against a human neutrophil extract and selected antigens and by immunofluorescence study using human neutrophils. Enzyme-linked immunospot assay was used for detecting ANCA-producing cells from spleen, mesenteric lymph node (MLN), or colon. RESULTS: Approximately 70% of sera from TCR-alpha-/- mice showed reactivity against human neutrophil extracts by enzyme-linked immunosorbent assay. Sixty percent of ANCA-positive sera showed a perinuclear reaction pattern. By enzyme-linked immunospot, ANCA-producing cells were detected in MLN and colon and less often in the spleen of TCR-alpha-/- mice with chronic colitis. The predominant immunoglobulin isotype of these autoantibodies was immunoglobulin A in the colon but not in the MLN and spleen. CONCLUSIONS: TCR-alpha-/- mice produce ANCAs. The ANCA (immunoglobulin A isotype)-producing B cells exist primarily in the diseased colonic mucosa of TCR-alpha-/- mice.

Animals↗

PubMed1997

Remyelination in the rat dorsal funiculus following demyelination by laser irradiation.

Excimer laser (KrF excimer laser, 248 nm wavelength) was used to damage cellular components in the dorsal funiculus at the lumbar level (L2) of the rat spinal cord. An open lesion was not found at the irradiation site on the spinal cord. However, the cytological examination revealed that cellular components were damaged to the depth of 200-500 microm from the pial surface. The characteristic feature was that at the border of the lesion, many axons remained naked but intact after their myelin sheaths had been completely disintegrated. Such naked axons were subsequently remyelinated by mature or immature glial cells. Mature oligodendrocytes, while retaining their cytoplasmic processes connected with the myelin sheaths of unaffected axons, extended new cytoplasmic processes on nearby naked axons and made new myelin sheaths around them. In contrast, 7 days after the irradiation, numerous immature glial cells appeared in association with naked axons, and some of them were differentiated into oligodendrocytes forming thin myelin sheaths on naked axons. These findings suggest that demyelinated axons can cause the proliferation and probably dedifferentiation of the oligodendrocyte lineage. The use of lasers provides a unique experimental model of demyelination and remyelination in the central nervous system of adult mammals.

Animals↗

PubMed1997

Bombyxin, an insulin-related peptide of insects, reduces the major storage carbohydrates in the silkworm Bombyx mori.

The effects of an insect insulin-related peptide, bombyxin, on carbohydrate metabolism were investigated in the silkworm Bombyx mori. Bombyxin lowered the concentration of the major hemolymph sugar, trehalose, in a dose-dependent manner when injected into neck-ligated larvae. Bombyxin also caused elevated trehalase activity in the midgut and muscle, suggesting that bombyxin induces hypotrehalosemia by promoting the hydrolysis of hemolymph trehalose to glucose and thereby facilitating its transport into tissues. In addition, bombyxin reduced the glycogen content in the fat body and concurrently raised the percentage of active glycogen phosphorylase in this tissue. Because hemolymph trehalose is also a major storage form of carbohydrate in insects, our results indicate that bombyxin reduces the amount of both principal storage carbohydrates in B. mori larvae. It is therefore suggested that although bombyxin is involved in the control of carbohydrate metabolism like insulin, the physiological role of bombyxin in insects is different from that of insulin in mammals.

Animals↗

PubMed1997

Immunocytochemical distribution of Ca(2+)-independent protein kinase C subtypes (delta, epsilon, and zeta) in regenerating axonal growth cones of rat peripheral nerve.

In the peripheral nerve, regenerating axonal sprouts usually emanate at nodes of Ranvier, and extend as growth cones along the inner surface of Schwann cells and/or through Schwann cell columns in the distal nerve segment. In order to elucidate the significance of Ca(2+)-independent protein kinase C in nerve regeneration, localizations of delta, epsilon and zeta subtypes were examined immunocytochemically in sprouts and growth cones of regenerating axons, as well as in normal intact nerves in the rat sciatic nerve. In normal nerves, intense immunoreactivities of delta, epsilon and zeta subtypes were present in axons of both myelinated and unmyelinated fibres. Subcellularly, the distribution of these subtypes in the axoplasm was patchy, and discontinuous in the axolemma and subaxolemmal peripheral zones of myelinated nerves. Some thin myelinated axons showed no immunoreactivity for epsilon subtype. Schwann cells of both myelinated and unmyelinated fibres had moderate immunoreactivities for each subtype. In areas of nerve regeneration, axonal sprouts at nodes of Ranvier, and growth cones extending along Schwann cell basal laminae, had intense immunoreactivities for delta, epsilon and zeta subtypes which are distributed diffusely throughout the axoplasm, and on the entire axolemma. In the sprouts, immunoreactivity for epsilon subtype was strong on the axolemma, but weak or almost absent in the axoplasm. These data, together with those of our previous study, indicate that Ca(2+)-independent protein kinase C subtypes (delta, epsilon and zeta) have basically the same distribution patterns as those of Ca(2+)-dependent subtypes in sprouts and growth cones of regenerating axons, as well as in normal intact axons; albeit epsilon subtype is somewhat different in distribution and intensity from delta and zeta subtypes. It is suggested that Ca(2+)-independent subtypes are involved in maintaining growth cone activities along with the Ca(2+)-dependent subtypes.

Amino Acid Sequence↗

PubMed1997

Basic fibroblast growth factor promotes extension of regenerating axons of peripheral nerve. In vivo experiments using a Schwann cell basal lamina tube model.

Schwann cell basal lamina tubes serve as attractive conduits for regeneration of peripheral nerve axons. In the present study, by using basal lamina tubes prepared by in situ freeze-treatment of rat saphenous nerve, the effects of exogenously applied basic fibroblast growth factor (bFGF) on peripheral nerve regeneration was examined 2 and 5 days after bFGF administration. Regenerating axons were observed by light and electron microscopy using PGP9.5-immunohistochemistry for specific staining of axons. In addition, the localizations of bFGF and its receptor (FGF receptor-1) were examined by immunohistochemistry using anti-bFGF antibody and anti-FGF receptor-1 antibody, respectively. Regenerating axons extended further in the bFGF-administered segment than in the bFGF-untreated control segment. Electron microscopy showed that regenerating axons grew out unaccompanied by Schwann cells. Findings concerning angiogenesis and Schwann cell migration were very similar between the bFGF treated and control nerve segment. bFGF-immunoreactivity was not detected in the control nerve segment. In contrast, bFGF-immunoreactivity was detected on the basal lamina tubes as well as on the plasmalemma of regenerating axons facing the basal lamina in the bFGF treated nerve segment up to 5 days after administration, suggesting that exogenous bFGF can be retained in the basal lamina for several days after administration. FGF receptor was detected on the plasma membrane of regenerating axons where they abutted the basal lamina. These results indicate that bFGF could promote the extension of early regenerating axons by directly influencing the axons, but not via Schwann cells or angiogenesis.

Animals↗

PubMed1997

Role of cytokines in the early stages of chronic colitis in TCR alpha-mutant mice.

Chronic colitis develops spontaneously in mice mutant for T-cell receptor alpha (TCR alpha) genes maintained in pathogen-free conditions. Our previous studies indicate that the cytokine imbalance caused by a lack of TCR alpha beta + T cells may be associated with the development of chronic colitis in TCR alpha-mutant (TCR alpha -/-) mice. The histologic changes of chronic colitis are recognizable by 3 to 4 months of age and are characterized by marked crypt cell hyperplasia and the presence of an inflammatory cell infiltrate. Because early events in the development of chronic colitis may be important in the pathogenesis of the disorder, we investigated the changes in the colon at a time when chronic colitis was not yet histologically recognizable. In vivo labeling with 5-bromo-2'-deoxyuridine revealed increased epithelial proliferation in the crypts by 6 to 8 weeks of age. There was an increase in number of T cells in the colon of TCR alpha -/- mice compared with that in TCR alpha +/- (heterozygous TCR alpha-mutant) mice after 6 weeks of age. The predominant T-cell subsets were CD4+, TCR alpha- beta +, and TCR gamma delta + cells. Reverse transcription-PCR and immunohistochemistry of the colonic mucosa obtained from TCR alpha -/- mice (> 6 weeks old) showed a marked increase of IL-1 alpha and IL-1 beta but not of TNF alpha or transforming growth factor beta-1 compared with TCR alpha +/- mice. In vivo neutralization of IL-1 alpha or IL-1 beta by specific mAb suppressed colonic epithelial proliferation and decreased colonic mucosal T-cell infiltration in 8-week-old TCR alpha -/- mice. These results provide direct evidence that overproduction of IL-1 alpha and IL-1 beta in the colonic mucosa may play an important role in the early stages of development of chronic colitis in TCR alpha -/- mice.

Animals↗

PubMed1997

[Chronic interstitial pneumonia and crescentic glomerulonephritis associated with perinuclear antineutrophil cytoplasmic antibodies].

We examined a 72-year-old man suffering from chronic interstitial pneumonia with crescentic glomerulonephritis associated with perinuclear antineutrophil cytoplasmic antibodies (P-ANCA). Ten years before admission, he was given a diagnosis of interstitial pneumonia, but received no medication. He was admitted to our hospital because of a high fever and back pain. Antibiotics were used, but without success. The serum P-ANCA titer was high, and examination of a kidney biopsy specimen showed crescentic glomerulonephritis. Computed tomography of the chest showed that the lungs had a honecomblike appearance, and examination of a specimen obtained by transbronchial lung biopsy showed interstitial fibrosis. This case shows that interstitial pneumonia can be associated with P-ANCA. It is important to be a wore that crescentic glomerulonephritis associated with P-ANCA can develop in patients with interstitial pneumonia.

Aged↗

PubMed1997

[Clinical investigation of three cases of pulmonary eosinophilic granuloma].

Patient 1: An 18-year-old woman was admitted to our hospital with pneumothorax. She had no history of smoking. Chest CT showed multiple cysts, and pulmonary eosinophilic granuloma was diagnosed by open lung biopsy. She recovered without therapy 3 months later and a chest CT taken at that time was normal. She began smoking, 3 years later, and bore two children. She is without recurrence after 8 years. Patient 2: A 23-year-old man was admitted to our hospital with pneumothorax. He had a smoking history (index = 180). Chest CT showed multiple cysts, and pulmonary eosinophilic granuloma was diagnosed by open lung biopsy. He stopped smoking and recovered without therapy one month later, and subsequently, his CT findings returned to normal. Two years later, he began smoking again, but has no relapse. Patient 3: A 21-year-old man was admitted to our hospital with pneumothorax. He had no history of smoking. A chest CT showed multiple cysts, and pulmonary eosinophilic granuloma was diagnosed by open lung biopsy. Diabetes insipidus was subsequently noted. Dyspnea persisted, and he recovered 4 months later after steroid treatment. He was without relapse 2 years later but the multiple cysts remained. We report three cases of pulmonary eosinophilic granuloma, and discuss their pertinent clinical features.

Adult↗

PubMed1996

Role of appendix in the development of inflammatory bowel disease in TCR-alpha mutant mice.

T cell receptor-alpha mutant mice (TCR-alpha-/-), created by gene targeting of the TCR-alpha gene in embryonic stem cells, spontaneously develop inflammatory bowel disease (IBD) resembling human ulcerative colitis. Since gut-associated lymphoid tissue is likely to play an important role in the development of chronic intestinal inflammation, we examined the changes in the appendix lymphoid follicle (ALF) and Peyer's patches (PP) in these mice. We found the structure of the ALF to be remarkably similar to that of the PP in the small intestine; in both instances, lymphoid follicles covered by surface epithelium (dome-formation) were found. The amount of proliferation in the lymphoid follicles of the appendix estimated by in vivo incorporation of 5-bromo-2'deoxyuridine was more than two times that of PP in TCR-alpha-/- mice. ELISPOT assay showed an increase of IgA, IgG1, and IgG2a, but not IgM-secreting B cells in ALF of TCR-alpha-/- mice compared to TCR-alpha+/- control mice. Furthermore, TCR-alpha-/- mice revealed an increase of autoantibody-producing B cells against the cytoskeletal protein tropomyosin in ALF as compared to PP. When TCR-alpha-/- mice underwent appendectomy at a young age (3-5 wk), the number of mesenteric lymph nodes cells at 6-7 mo were markedly less than in the sham-operated TCR-alpha-/- mice. Furthermore, appendectomy at 1 mo of age suppressed the development of IBD, with only 3.3% of these mice developing IBD in the 6-7-mo period of observation. In contrast, approximately 80% of controls, including the sham-operated TCR-alpha-/- mice, developed IBD during this period. These results suggest that ALF, rather than PP, is the priming site of cells involved in the disease process and plays an important role in the development of IBD in TCR-alpha-/- mice.

Animals↗

PubMed1996

Cytokine imbalance and autoantibody production in T cell receptor-alpha mutant mice with inflammatory bowel disease.

Spontaneous inflammatory bowel disease (IBD) resembling human ulcerative colitis develops in mice mutant for the T cell receptor alpha gene (TCR-alpha-/-). TCR-alpha-/- mice lack TCR-alpha/beta+ cells but contain TCR-gamma/delta+ cells and a small population of a unique CD4+, TCR-alpha-/beta+(low) cells. Since all the immunoglobulin (Ig) classes are present in these mice, help to B cells must be provided by cells other than TCR-alpha/beta+ cells. In the present study, we found serum levels of IgG1 and IgG2 to be markedly increased in TCR-alpha-/- mice with IBD as compared to TCR-alpha-/- mice without IBD or TCR-alpha+/- controls. An increase in IgG1-, IgG2a- and IgA- but not IgM-secreting mesenteric lymph node (MLN) B cells was detected in TCR-alpha-/- mutant mice. There was also a marked increase in MLN B cells secreting autoantibody (IgG) to tropomyosin, a cytoskeletal protein. Examination of the hyperplastic MLN showed a marked increase in the number of B, TCR-delta+, and CD4+ TCR-alpha-/beta+ cells, similar to the cell population observed at the site of colonic inflammation. Analysis of spontaneous cytokine production by MLN cells using an enzyme-linked immunospot assay, immunohistochemistry, and reverse transcription/polymerase chain reaction showed a decrease of interleukin 2 (IL-2) but a marked increase of IL-4 and interferon gamma (IFN-gamma) production in TCR-alpha-/- mice with IBD as compared to TCR-alpha-/- mice without IBD and TCR alpha+/- control mice. Both TCR-alpha-/beta+ and TCR-delta+ cells were found to be capable of producing IL-4; IFN-gamma was produced mostly by non-T cells, many of which were shown to be CD3- NK 1.1+ cells. We propose that the cytokine imbalance present in these mice results in expansion of B cells, production and switching of autoantibodies to IgG2 subclass, and development of IBD. It is possible that the unusual CD4+ TCR-alpha-/beta+ population and expanded TCR-gamma/delta+ population present in TCR-alpha-/- mice plays a central role in this abnormal immune response.

Animals↗

PubMed1996

Bombyx and Manduca prothoracicotropic hormones: an immunologic test for relatedness.

Prothoracicotropic hormone (PTTH) controls the synthesis of ecdysteroids (molting hormones) by the insect prothoracic gland and thereby plays a critical role in insect growth, molting, and metamorphosis. PTTH has been purified, and cDNA clones obtained, from only one insect, the silkmoth Bombyx mon. Recently, a partial amino acid sequence was obtained for-a putative PTTH from the tobacco hornworm, Manduca sexta, and the data suggested an unexpected homology to a vertebrate retinoid binding protein rather than to the Bombyx PTTH. In this study, a monoclonal antibody against the Bombyx PTTH was added to in vitro assays that assess the ability of partially purified Manduca PTTH to stimulate prothoracic gland ecdysteroid and protein synthesis. The results indicate that Bombyx and Manduca PTTHs are indeed members of the same protein family that have likely diverged in the PTTH receptor-binding region.

Adsorption↗

PubMed1996

Localization of synapsin I in normal fibers and regenerating axonal sprouts of the rat sciatic nerve.

The localization of synapsin I, a synaptic vesicle-associated protein, was investigated immunocyto-chemically in normal nerve fibers and regenerating axonal sprouts following crush-injuries to the rat sciatic nerve. In normal myelinated axons, weak synapsin I immunoreactivity was found in the axoplasmic/smooth endoplasmic domains, but not in the cytoskeletal domains comprising neurofilaments and microtubules. In non-myelinated axons without dense cytoskeletal structures, moderate immunoreactivity was distributed diffusely throughout the axoplasm. In the crush-injured nerves, intense synapsin I immunoreactivity was demonstrated by light microscopy in early regenerating sprouts emerging from nodes of Ranvier. These nodal sprouts subsequently elongated as regenerating axons through the space between the basal lamina and the myelin sheath (or Schwann cell plasma membrane). Intense synapsin I immunoreactivity was also found in the growth cones of such long regenerating axons. Electron microscopy revealed that synapsin I immunoreactivity was associated mainly with vesicular organelles in the nodal sprouts and growth cones of regenerating axons. Long regenerating axons exhibited no synapsin I immunoreactivity in the shaft, which contained an abundance of neurofilaments. However, vesicle accumulations remaining in the periphery of the shaft still exhibited intense synapsin I immunoreactivity. Thus, it can be concluded that synapsin I is localized at especially high density in the domains comprising vesicular organelles, which are characteristic of early nodal sprouts, as well as in growth cones of regenerating axons. These findings, together with the proposed functions of synapsin I investigated in other studies, suggest that synapsin I may play important roles in vesicular dynamics including the translocation of vesicles to the plasma membrane in sprouts and growth cones of regenerating axons.

Animals↗

PubMed1996

Alpha N-catenin expression in the normal and regenerating chick sciatic nerve.

The Ca(2+)-dependent intercellular adhesion molecule cadherin is known to be linked to the cytoskeleton by the protein catenin, an association of which appears to be important for the cell-adhesion function of cadherin. Catenin consists of three subtypes-alpha, beta, and gamma. In our previous study, N-cadherin was shown to be localized on the plasmalemma of normal and regenerating chick peripheral nerve. Thus, as alpha N-catenin is a subtype of alpha-catenin (which is specifically associated with N-cadherin), we investigated the immunolocalization of alpha N-catenin in normal and regenerating chick sciatic nerve. In normal nerve, unmyelinated axons exhibited either intense or weak alpha N-catenin immunoreactivity throughout the axoplasm, whereas myelinated axons were completely immunonegative. Regenerating axons, including those derived from parent myelinated axons, showed alpha N-catenin immunoreactivity of variable intensities in growth cones and axon shafts. Schwann cells were invariably devoid of immunoreactivity. Thus alpha N-catenin is not necessarily bound to the surface plasmalemma, but is distributed throughout the cytoplasm, suggesting that most alpha N-catenin molecules are dissociated from N-cadherin.

Animals↗