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Query: EC:3.4.11.18 (MAP)
 7,412 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Within the olfactory epithelium is a stem cell which can divide and differentiate to produce new sensory neurons. The identity of the neuronal stem cell is unknown but one candidate is the horizontal basal cell which lies adjacent to the basement membrane and expresses keratin. Previous attempts to generate mature sensory neurons from purified horizontal basal cells in vitro were unsuccessful. We show here for the first time that olfactory neurogenesis can be reproduced in vitro from partially-purified cultures of adult rat precursor cells cultivated in a serum-free medium. Rat olfactory epithelium was dissected from the nasal septum and separated from the underlying lamina propria, and its cells were dissociated and grown in a medium containing epidermal growth factor for 5 days. Immunochemistry showed that only supporting cells (SUS1-positive) and horizontal basal cells (keratin-positive) survived for this period. At day 6, the cells were stressed either by passaging them or by a simple mechanical stress. In each case, a morphological and immunological differentiation was observed within 24-48 hr. Newly formed bipolar cells were found to be S100-, glial fibrillary acidic protein (GFAP-), neural cell adhesion molecule (N-CAM+), and/or microtubule-associated protein 5 (MAP-5+). After passaging 14% of the surviving cells were immature neurons (MAP-5+) and 4% were mature olfactory neurons (MAP-5+) and olfactory marker protein (OMP+)). In addition the same experiment was conducted on transgenic mice in which the lacZ gene was linked to the OMP promoter. Using 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-Gal) staining we showed that OMP+ cells disappeared before day 5 in culture but reappeared after passaging. These results suggest that olfactory sensory neurons can arise from a non-neuronal precursor, probably the keratin-positive horizontal basal cell.
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PMID:Generation of neurons from a nonneuronal precursor in adult olfactory epithelium in vitro. 992 9

Cells within human skin are permanently exposed to mechanical stretching. Here we present evidence that alterations in cell shape trigger biochemical signaling via MAP kinases in human keratinocytes. In an in vitro attempt we demonstrate a fast but transient activation of extracellular signal-regulated kinases 1/2 in response to cell stretch. This activation is reversed by preincubation with functional blocking antibodies directed towards beta1-integrins. As a second member of MAP kinases, stress-activated protein kinase/c-JUN NH2-terminal kinase was activated in a slower fashion, peaking at 1 h after the initial stimulus. The delay in signal transmission suggests that extracellular signal-regulated kinases 1/2 and stress-activated protein kinase/c-JUN NH2-terminal kinase do not share the same signaling pathway. p38 was not activated by cell stretching. The contribution of cytoskeletal elements in signal perception and transduction was evaluated by selective disruption of either actin filaments, microtubules, or keratin filaments but showed no clear effect on stretch-induced activation of extracellular signal-regulated kinases 1/2 and stress-activated protein kinase/c-JUN NH2-terminal kinase. In conclusion we found evidence of a cell-shape-dependent activation of MAP kinases in human keratinocytes disclosing beta1-integrins as putative mechano-transducers. It is likely that alterations of skin mechanics in vivo underlying pathogenic processes like wound formation and healing trigger physiologic responses via the MAP kinase pathway.
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PMID:Signaling of mechanical stretch in human keratinocytes via MAP kinases. 1144 68

The Arabidopsis thaliana genome encodes about 386 proteins with coiled-coil domains of at least 50 amino acids in length. In mammalian systems, many coiled-coil proteins are part of various cytoskeletal networks including intermediate filament protein, actin-binding proteins and MAP (microtubule-associated proteins). Immunological evidence suggests that some of these cytoskeletal proteins, such as lamins, keratins and tropomyosins, may be conserved in Arabidopsis. However, coiled-coil proteins are of low complexity, and thus, traditional sequence comparison algorithms, such as BLAST may not detect homologies. Here, we use the PROPSEARCH algorithm to detect putative coiled-coil cytoskeletal protein homologues in Arabidopsis. This approach reveals putative intermediate filament protein homologues of filensin, lamin and keratin; putative actin-binding homologues of ERM (ezrin/radixin/moesin), periplakin, utrophin, tropomyosin and paramyosin, and putative MAP homologues of restin/CLIP-170 (cytoplasmic linker protein-170). We suggest that the AtFPP (Arabiopsis thaliana filament-like plant protein) and AtMAP70 (Arabidopsis microtubule-associated protein 70) families of coiled-coil proteins may, in fact, be related to lamins and function as intermediate filament proteins.
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PMID:Putative Arabidopsis homologues of metazoan coiled-coil cytoskeletal proteins. 2128 6

The papillomavirus E4 open reading frame (ORF) is contained within the E2 ORF, with the primary E4 gene-product (E1^E4) being translated from a spliced mRNA that includes the E1 initiation codon and adjacent sequences. E4 is located centrally within the E2 gene, in a region that encodes the E2 protein's flexible hinge domain. Although a number of minor E4 transcripts have been reported, it is the product of the abundant E1^E4 mRNA that has been most extensively analysed. During the papillomavirus life cycle, the E1^E4 gene products generally become detectable at the onset of vegetative viral genome amplification as the late stages of infection begin. E4 contributes to genome amplification success and virus synthesis, with its high level of expression suggesting additional roles in virus release and/or transmission. In general, E4 is easily visualised in biopsy material by immunostaining, and can be detected in lesions caused by diverse papillomavirus types, including those of dogs, rabbits and cattle as well as humans. The E4 protein can serve as a biomarker of active virus infection, and in the case of high-risk human types also disease severity. In some cutaneous lesions, E4 can be expressed at higher levels than the virion coat proteins, and can account for as much as 30% of total lesional protein content. The E4 proteins of the Beta, Gamma and Mu HPV types assemble into distinctive cytoplasmic, and sometimes nuclear, inclusion granules. In general, the E4 proteins are expressed before L2 and L1, with their structure and function being modified, first by kinases as the infected cell progresses through the S and G2 cell cycle phases, but also by proteases as the cell exits the cell cycle and undergoes true terminal differentiation. The kinases that regulate E4 also affect other viral proteins simultaneously, and include protein kinase A, Cyclin-dependent kinase, members of the MAP Kinase family and protein kinase C. For HPV16 E1^E4, these kinases regulate one of the E1^E4 proteins main functions, the association with the cellular keratin network, and eventually also its cleavage by the protease calpain which allows assembly into amyloid-like fibres and reorganisation of the keratin network. Although the E4 proteins of different HPV types appear divergent at the level of their primary amino acid sequence, they share a recognisable modular organisation and pattern of expression, which may underlie conserved functions and regulation. Assembly into higher-order multimers and suppression of cell proliferation are common to all E4 proteins examined. Although not yet formally demonstrated, a role in virus release and transmission remains a likely function for E4.
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PMID:The E4 protein; structure, function and patterns of expression. 2401 39