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PubMed1984

Microtubule-associated proteins connect microtubules and neurofilaments in vitro.

Neuronal intermediate filaments (neurofilaments) prepared from brain form a viscous sedimentable complex with microtubules under suitable conditions [Runge, M.S., Laue, T.M., Yphantis, D.A., Lifsics, M.R., Saito, A., Altin, M., Reinke, K., & Williams, R.C., Jr. (1981) Proc. Natl. Acad. Sci. U.S.A. 78, 1431-1435]. Under the same conditions, neurofilaments prepared from spinal cord did not form such a complex. Brain neurofilaments were shown to differ from spinal cord neurofilaments in part by having proteins that resemble microtubule-associated proteins (MAPs) attached to them. MAPs became bound to spinal cord neurofilaments when the two structures were incubated together. The resulting MAP-decorated neurofilaments formed a viscous complex with microtubules, showing that some component of the MAPs mediated the association between the two filamentous organelles. By means of gel filtration, the MAPs were separated into two major fractions. The large Stokes radius fraction was active in producing neurofilament-microtubule mixtures of high viscosity, while the small Stokes radius fraction was not. The dependence of the viscosity of neurofilament-microtubule mixtures upon the concentration of MAPs was found to possess a maximum. This result suggests that the MAPs serve as cross-bridges between the two structures. Neurofilaments, with and without bound MAPs, were allowed to adhere to electron microscope grids. The grids were then exposed to microtubules, fixed, and stained. The grids prepared with MAP-decorated neurofilaments bound numerous microtubules, each in apparent contact with one or more neurofilaments. The grids prepared with untreated neurofilaments lacked microtubules. These results show that one or more of the MAPs mediates association between microtubules and neurofilaments.

Adenosine Triphosphate↗
PubMed2006

Evaluation of concept mapping in an associate degree nursing program.

The purpose of this project was to evaluate concept mapping as a clinical teaching-learning activity that reflects critical thinking by promoting identification of nonlinear relationships among the components of the nursing process. The sample involved 28 associate degree nursing students from one graduating class. Students completed one map each in the second and fourth semesters and two maps in the fifth semester, for a total of four concept maps. The students' learning activity was to create a concept map on a blank sheet of paper describing the clients' physiological and psychosocial needs and nursing care and the relationships among concepts. As students progressed through the curriculum, there was a steady increase in the mean scores and the average number of cross-links in their concept maps. Cross-links indicated students' ability to use nonlinear thinking to identify relationships among concepts. The results of this study support the use of concept maps as an effective teaching-learning activity and support concept mapping as an evidence-based nursing education strategy.

Adult↗
PubMed1995

Abnormal expression of microtubule-associated protein 2 (MAP-2) in neocortex in Rett syndrome.

Immunocytochemical evaluations of the neocortex of three classical Rett syndrome (RS) individuals revealed a selective abnormality in the expression of microtubule-associated protein 2 (MAP-2). MAP-2 immunoreactivity (ir) was reduced throughout the neocortex of all three RS cases with a reversal of the normal pattern of more intense staining in deep cortical layers. This anomaly was selective for MAP-2 because nonphosphorylated neurofilament (SMI-32) labeling of deep pyramidal neurons and calbindin (CaBP)-stained GABAergic cells remained unchanged. Moreover, MAP-2 ir was virtually undetected in white matter while GABAergic and, particularly, peptidergic (neuropeptide Y: NPY) profiles were easily recognized. These results demonstrate a marked disruption of a major cytoskeletal component in neocortex in RS which seems to affect, predominantly, pyramidal projection and white matter neurons. MAP-2 expression appears early in neuronal maturation of the neocortex, particularly in the subplate region, the future superficial white matter, suggesting that these reported abnormalities in RS represent a developmental disturbance. Considering that MAP-2 expression is regulated by several neurotransmitter systems in adult cerebral cortex, particularly dopaminergic and cholinergic afferents that are deficient in RS, these neurochemical alterations could be related to this anomalous MAP-2 expression.

Adult↗
PubMed1992

Immunocytochemical localization of 205 kDa microtubule-associated protein (205 kDa MAP) in the guinea pig organ of Corti.

We have studied the immunocytochemical localization of microtubule-associated proteins (MAPs) in the guinea pig organ of Corti. Using immunological methods with antibodies against MAP1A, MAP1B, MAP2, tau and 205 kDa MAP, we have identified 205 kDa MAP as a major MAP of the sensory epithelium in the organ of Corti. Immunoperoxidase microscopic study has shown that both cochlear hair cells and supporting cells reacted with anti-205 kDa MAP antibody. Immunoelectron microscopy revealed that 205 kDa MAP was associated with most microtubules in the sensory epithelial cells. It was also associated with the microtubules of bundle structures within supporting cells, suggesting that this MAP might form a part of cross-bridges between microtubules and between microtubules and actin filaments in the bundle structure. In contrast, MAP1A, MAP1B and tau, which are known to be expressed in neuronal tissue, were localized only in nerve fibers in the organ of Corti, not in the sensory epithelium. MAP2, which is known to be localized in dendrites and soma of nerve cells, was not distributed in nerve fibers in the organ of Corti. These results suggest possible roles of the 205 kDa MAP in the formation and maintenance of the highly polarized morphology of the epithelial cells of the organ of Corti, through stabilization and modulation of microtubule networks of these cells.

Animals↗
PubMed2002

Microtubule-associated protein 2 (MAP-2) is expressed in low and high grade diffuse astrocytomas.

The expression of neuronal antigens in diffuse astrocytomas has not been thoroughly evaluated. We have investigated the expression of microtubule associated protein 2 (MAP-2), synaptophysin and non-phosphorylated epitopes of neurofilament protein (NFP) by immunohistochemistry in 15 low grade diffuse astrocytomas and 15 glioblastomas. MAP-2 was strongly expressed in 97% of cases, using an antibody to both low and high molecular weight isoforms. An antibody specific to high molecular weight isoforms of MAP-2 (hmw-MAP-2) revealed weaker, focal staining in 60% of cases with greater expression in the glioblastomas (P=0.027). NFP was expressed in 50% of cases, but was generally weak and focal. There was little evidence of synaptophysin expression. We conclude that MAP-2 expression in astrocytomas is due predominantly to low molecular weight isoforms, which may be expressed in astrocytes as well as neurons. Focal expression of hmw-MAP-2 and NFP, however, suggest that neuronal antigens may be expressed, particularly in high grade astrocytomas. Immunopositivity for these antigens should not preclude the diagnosis of diffuse astrocytoma.

Adult↗
PubMed1984

Widespread distribution of the major polypeptide component of MAP 1 (microtubule-associated protein 1) in the nervous system.

We prepared a monoclonal antibody to microtubule-associated protein 1 (MAP 1), one of the two major high molecular weight MAP found in microtubules isolated from brain tissue. We found that MAP 1 can be resolved by SDS PAGE into three electrophoretic bands, which we have designated MAP 1A, MAP 1B, and MAP 1C in order of increasing electrophoretic mobility. Our antibody recognized exclusively MAP 1A, the most abundant and largest MAP 1 polypeptide. To determine the distribution of MAP 1A in nervous system tissues and cells, we examined tissue sections from rat brain and spinal cord, as well as primary cultures of newborn rat brain by immunofluorescence microscopy. Anti-MAP 1A stained white matter and gray matter regions, while a polyclonal anti-MAP 2 antibody previously prepared in this laboratory stained only gray matter. This confirmed our earlier biochemical results, which indicated that MAP 1 is more uniformly distributed in brain tissue than MAP 2 (Vallee, R.B., 1982, J. Cell Biol., 92:435-442). To determine the identity of cells and cellular processes immunoreactive with anti-MAP 1A, we examined a variety of brain and spinal cord regions. Fibrous staining of white matter by anti-MAP 1A was generally observed. This was due in part to immunoreactivity of axons, as judged by examination of axonal fiber tracts in the cerebral cortex and of large myelinated axons in the spinal cord and in spinal nerve roots. Cells with the morphology of oligodendrocytes were brightly labeled in white matter. Intense staining of Purkinje cell dendrites in the cerebellar cortex and of the apical dendrites of pyramidal cells in the cerebral cortex was observed. By double-labeling with antibodies to MAP 1A and MAP 2, the presence of both MAP in identical dendrites and neuronal perikarya was found. In primary brain cell cultures anti-MAP 2 stained predominantly cells of neuronal morphology. In contrast, anti-MAP 1A stained nearly all cells. Included among these were neurons, oligodendrocytes and astrocytes as determined by double-labeling with anti-MAP 1A in combination with antibody to MAP 2, myelin basic protein or glial fibrillary acidic protein, respectively. These results indicate that in contrast to MAP 2, which is specifically enriched in dendrites and perikarya of neurons, MAP 1A is widely distributed in the nervous system.

Animals↗
PubMed1984

Widespread cellular distribution of MAP-1A (microtubule-associated protein 1A) in the mitotic spindle and on interphase microtubules.

In the accompanying paper (Bloom, G.S., T.A. Schoenfeld, and R.B. Vallee, 1983, J. Cell Biol. 98:320-330), we reported that microtubule-associated protein 1 (MAP 1) from brain comprises multiple protein species, and that the principal component, MAP 1A, can be detected in both neuronal and glial cells by immunofluorescence microscopy using a monoclonal antibody. In the present study, we sought to determine the cellular and subcellular distribution of MAP 1A in commonly used cultured cell systems. For this purpose we used immunofluorescence microscopy and immunoblot analysis with anti-MAP 1A to examine 18 types of mammalian cell cultures. MAP 1A was detected in every culture system examined. Included among these were cells of mouse, rat, Chinese hamster, Syrian hamster, Potoroo (marsupial), and human origin derived from a broad variety of tissues and organs. Anti-MAP 1A consistently labeled mitotic spindles and stained cytoplasmic fibers during interphase in most of the cultures. These fibers were identified as microtubules by co-localization with tubulin in double-labeling experiments, by their disappearance in response to colchicine or vinblastine, and by their reorganization in response to taxol. The anti-MAP 1A stained microtubules in a punctate manner, raising the possibility that MAP 1A is located along microtubules at discrete foci that might represent sites of interaction between microtubules and other organelles. Verification that MAP 1A was, indeed, the reactive material in immunofluorescence microscopy was obtained from immunoblots. Anti-MAP 1A stained a band at the position of MAP 1A in all cultures examined. These results establish that MAP 1A, a major MAP from brain, is widely distributed among cultured mammalian cells both within and outside of the nervous system.

Alkaloids↗
PubMed2002

Immunocytochemical expression of microtubule-associated protein-2 (MAP-2) in small cell lung cancer cell lines with neuronal-like processes.

Five of six human small cell lung cancer (SCLC) cell lines changed morphologically into cells with neuronal-like processes on the extracellular matrix of human lung adenocarcinoma cell line PC-9 cells (PC-9 / ECM substrate). The features of the neuronal-like processes of these SCLC cell lines were examined immunocytochemically using monoclonal antibodies against beta-chains of tubulin and microtubule-associated protein-2 (MAP-2), which is somatodendritic MAP of neurons. It was observed that beta-chains of tubulin and MAP-2 were expressed along the neuronal-like processes of SCLC cell lines. These findings suggest that the beta-chains of tubulin and MAP-2 are expressed functionally in SCLC cell lines in association with the development of dendrite-like processes on PC-9 / ECM substrate.

Carcinoma, Small Cell↗
PubMed2005

A study of a dendritic marker, microtubule-associated protein 2 (MAP-2), in rats neonatally treated neurosteroids, pregnenolone and dehydroepiandrosterone (DHEA).

Neurosteroids administered during the neonatal period affect the development of several brain systems. We examined the effects of neonatal treatment with pregnenolone and dehydroepiandrosterone (DHEA) on a marker of neuronal dendrites, microtubule-associated protein 2 (MAP-2), in rat brain. Neonatal treatment with pregnenolone and DHEA increased the expression of MAP-2 in the hippocampus and nucleus accumbens but not in the prefrontal cortex, striatum or amygdala in adulthood.

Animals↗
PubMed1993

The chemotactic factor N-formylmethionyl-leucyl-phenylalanine activates microtubule-associated protein 2 (MAP) kinase and a MAP kinase kinase in polymorphonuclear leucocytes.

Incubation of human polymorphonuclear leucocytes (PMN) with either the chemotactic factor N-formylmethionyl-leucylphenylalanine (FMLP) or phorbol 12-myristate 13-acetate (PMA) activates a kinase with phosphorylating activity towards a known microtubule-associated protein-2 (MAP) kinase substrate, the epidermal growth factor receptor peptide (T669). Activation of this enzyme by FMLP was maximal at 1 min, decreasing by 10 min. Activation by PMA was slightly slower than that by FMLP, but more prolonged (maximal at 5 min, with no significant decrease by 20 min). The enzyme induced by either stimulant bound strongly to phenyl-Sepharose, had a molecular mass of 40 kDa on gel filtration and phosphorylated three MAP kinase substrates, i.e. MAP, myelin basic protein and the T669 peptide. By use of antibodies to MAP kinases and phosphotyrosine, the enzyme was identified as the 42 kDa MAP kinase (also known as extracellular-signal-regulated kinase 2, ERK2). Stimulation of PMN with FMLP or PMA was also found to induce a kinase kinase which phosphorylated human recombinant MAP kinase on threonine and tyrosine, with concomitant activation. These results suggest that MAP kinase and the kinase kinase are involved in the activation of PMN by chemotactic factors such as FMLP.

Animals↗
PubMed1993

Calpain-mediated proteolysis of microtubule-associated protein 2 (MAP-2) is inhibited by phosphorylation by cAMP-dependent protein kinase, but not by Ca2+/calmodulin-dependent protein kinase II.

The effects of cAMP-dependent protein kinase (cAMP-PK) and Ca2+/calmodulin-dependent protein kinase II (CaMKII) phosphorylation on the calpain-mediated degradation of microtubule-associated protein 2 (MAP-2) were studied. Both cAMP-PK and CaMKII readily phosphorylated MAP-2. However, cAMP-PK phosphorylated MAP-2 to a significantly greater extent than did CaMKII (4.5 mol 32P/mol MAP-2 and 1.4 mol 32P/mol MAP-2, respectively). Phosphorylation of MAP-2 by cAMP-PK, but not by CaMKII, significantly inhibited the calpain-induced hydrolysis of MAP-2. These results demonstrate that the phosphorylation of sites on the MAP-2 molecule accessible to cAMP-PK, but not to CaMKII, result in increased resistance to calpain proteolysis.

Animals↗
PubMed1994

Comparative mapping of lipocalin genes in human and mouse: the four genes for complement C8 gamma chain, prostaglandin-D-synthase, oncogene-24p3, and progestagen-associated endometrial protein map to HSA9 and MMU2.

The lipocalin superfamily encompasses a large set of quite distantly related proteins that act as carriers for small, lipophilic molecules. The lipocalin genes coding for orosomucoid, the alpha 1-microglobulin/bikunin precursor, and the major urinary protein map to MMU4, while their human counterparts map to the homologous HSA9q34 area where three other lipocalin genes for complement C8 gamma chain (C8G), progestagen-associated endometrial protein (PAEP), and prostaglandin D synthase (PTGDS) are also located. By linkage analyses in an interspecific backcross progeny in mouse, the Lcn2 gene coding for the oncogenic lipocalin 24p3, as well as the 3 lipocalin genes for C8G, PTGDS, and PAEP, have now been assigned to MMU2. The first three genes map to proximal MMU2, which is known to be homologous to HSA9q34. Paep is more distally located, which extends the number of regions with conserved syntenies between HSA9q34 and MMU2. By in situ hybridization, the human LCN2 gene maps to HSA9q34. Our data indicate that the lipocalin locus arrangement in the human/mouse ancestor is closer to that found at HSA9q than to that in the MMU genome.

Acute-Phase Proteins↗
PubMed1987

18 kDa microtubule-associated protein: identification as a new light chain (LC-3) of microtubule-associated protein 1 (MAP-1).

SDS gel electrophoresis of microtubule proteins obtained from bovine brain by polymerization cycles revealed a new protein of 18 kDa. This protein was copolymerized with tubulin and its stoichiometry to tubulin remained constant for at least 5 cycles of assembly. Moreover, this protein remained bound to microtubules stabilized with 10 microM taxol and pelleted through a 4 M glycerol cushion. The same 18 kDa protein was found in a purified preparation of the high molecular mass microtubule-associated protein 1 (MAP-1). The 18 kDa protein copurified with the MAP-1 heavy chains during column chromatography on phosphocellulose, DEAE-cellulose, hydroxyapatite and Bio-Gel A-15m. Incubation of the MAP-1 preparation with a mouse monoclonal antibody to the light chain 1 (LC-1) of MAP-1 and with a second precipitating antibody (a rabbit antibody to mouse IgG) immunoprecipitated from the solution all the known components of MAP-1 (heavy chains, LC-1, LC-2), as well as the 18 kDa protein. Immunoblotting showed, however, that this antibody does not interact directly with the 18 kDa protein. These results indicate that the 18 kDa protein forms a complex with all other components of MAP-1. This polypeptide, therefore, is a new light chain (LC-3) of MAP-1.

Animals↗
PubMed2006

Microtubule-associated protein-4 (MAP-4) inhibits microtubule-dependent distribution of mRNA in isolated neonatal cardiocytes.

OBJECTIVES: Active mRNA distribution in the form of ribonucleoprotein particles moving along microtubules has been shown in several cell types, but not yet in cardiocytes. This study addresses two hypotheses: 1) a similar mRNA distribution mechanism operates in cardiocytes; 2) decoration of microtubules with microtubule-associated proteins compromises this distribution. METHODS: To visualize ribonucleoproteins in cultured neonatal rat cardiocytes, they were transfected with vectors encoding zipcode binding protein-1 and Staufen fused with GFP. The velocity of microtubular transport and elongation were calculated on time-lapse confocal pictures. RESULTS: ZBP-1 and Staufen labeled particles co-localized with each other and with microtubules and moved along microtubules over a distance of 1-20 microm with a mean speed of 80 nm/s. The average speed decreased about 50% after decoration of microtubules by adenoviral microtubule-associated protein-4 (MAP-4). The elongation speed measured using the GFP-tagged end-binding protein-1 exceeded 200 nm/s and was not influenced by MAP-4. CONCLUSIONS: We demonstrate for the first time ribonucleoprotein particles in cardiocytes, their microtubular-related movement, and its inhibition (but not of the microtubular elongation), by the MAP-4 decoration of microtubules.

Animals↗
PubMed1989

Anti-200 kDa neurofilament antibody cross-reacts with microtubule-associated protein-2 (MAP-2).

An antibody prepared against purified 200-kDa neurofilament (NF) subunit was found to cross-react with a high molecular weight polypeptide present in rat brain cytoskeletal extracts starting from early postnatal development. This polypeptide was found to be highly concentrated in microtubule preparations and was specifically recognized as the 280-kDa microtubule-associated protein-2 (MAP-2). Our results, besides suggesting the existence of common epitopes between the heavy NF subunit and MAP-2, suggest the possibility of an interaction between two of the most important neuronal cytoskeletal organelles: NFs and microtubules.

Animals↗
PubMed2002

Nitric oxide affects the phosphorylation state of microtubule-associated protein 2 (MAP-2) and neurofilament: an immunocytochemical study in the brain of rats and neuronal nitric oxide synthase (nNOS)-knockouts.

Alterations in function and specific cellular location of cytoskeletal elements are characterized by changes in their phosphorylation state. On this background we studied immunocytochemically the distribution pattern of neurofilament (NF) in its phosphorylated (P-NF) and nonphosphorylated (NP-NF) form and of microtubule-associated protein-2 (MAP-2) in the rat and mouse brain. Neurons that are strongly positive for neuronal nitric oxide synthase (nNOS)-immunoreactivity (IR) showed, interestingly, neither P-NF- nor MAP-2-IR. In contrast, nNOS-negative neuronal cell elements exhibited an intense IR and specific location for both antigens throughout the brain. As a model we chose the dorsolateral tegmental nucleus (LDT) of knockout (nNOS(-/-)) mice in which the main splice isoform nNOSalpha is lacking, but a low nNOS-activity persists, apparently due to the splice isoforms nNOSbeta and gamma. The principal neurons of such nNOS(-/-)-mice, which are equivalent to the nNOS-containing neurons in the LDT of wild-type mice exhibited a decreased nitrotyrosine-IR and an increased phosphotyrosine-IR if compared to those of wild-type mice. The same neurons failed to show NF-IR and MAP-2-IR, though. When the residual nNOS activity in nNOS(-/-)-mice was inhibited by treatment with N-omega-nitro-L-arginine methyl ester (L-NAME) the principal neurons displayed a moderate MAP-2 and NF-staining. NO and NO-derived oxygen species are suggested to modulate the balance between the activities of kinases and phosphatases, thus changing phosphorylation levels for NF, MAP-2, and, possibly, other proteins in neurons and adjacent cell elements.

Animals↗