Evidence for the Stochastic Integration of Gene Trap Vectors into the Mouse Germline

Chowdhury, Kamal; Bonaldo, Paolo; Torres, Miguel; Stoykova, A.; Gruß, Peter

doi:10.1093/nar/25.8.1531

Cited by 82 publications

(61 citation statements)

References 16 publications

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“…The insertion of the vector into the MAP1B locus results in premature termination of MAP1B translation and the expression of a fusion protein with ␤-galactosidase and neomycin resistance activities, under the control of the MAP1B promoter (Chowdhury et al, 1997). Mice carrying this mutation express trace amounts of MAP1B, display severe cortical lamination defects, and die shortly after birth (Gonzalez-Billault et al, 2000).…”

Section: Delayed Axonal Formation and Growth Cone Abnormalities In Cumentioning

confidence: 99%

“…The generation of heterozygous mice lacking a copy of MAP1B by a gene trap approach has been described elsewhere (Chowdhury et al, 1997;Gonzalez-Billault et al, 2000). The gene-trapping vector (IRES␤geo) contained the EN-2 splice acceptor sequence, and IRES sequence, the neo gene, the lacZ gene, and the simian virus 40 polyadenylation signal.…”

Section: Generation and Genotyping Of Map1b Mutant Micementioning

confidence: 99%

“…MAP1B mutant mice were generated with the use of a gene trapping vector (IRES␤geo) transfected into R1 ES cells (Chowdhury et al, 1997; Figure 1A). The insertion of the vector into the MAP1B locus results in premature termination of MAP1B translation and the expression of a fusion protein with ␤-galactosidase and neomycin resistance activities, under the control of the MAP1B promoter (Chowdhury et al, 1997).…”

Section: Delayed Axonal Formation and Growth Cone Abnormalities In Cumentioning

confidence: 99%

“…(Takei et al, 2000) Unfortunately, none of these studies examined the consequences of MAP1B gene suppression on cytoskeletal organization, and therefore the functional involvement of MAP1B as a key regulator of microtubule dynamics during neuronal polarization has remained largely unexplored. In the present study, we have addressed this issue by examining the morphology, cytoskeletal organization, and dynamics of microtubule assembly in cultured hippocampal pyramidal neurons from a hypomorphous MAP1B mutant mouse line (Gonzalez-Billault et al, 2000) obtained by a gene-trapping approach (Chowdhury et al, 1997). …”

mentioning

confidence: 99%

“…The gene-trapping vector (IRES␤geo) contained the EN-2 splice acceptor sequence, and IRES sequence, the neo gene, the lacZ gene, and the simian virus 40 polyadenylation signal. To genotype MAP1B mutant mice, genomic DNA from mouse tails were isolated and analyzed by polymerase chain reaction with oligonucleotides corresponding to the neo sequence (Chowdhury et al, 1997). …”

mentioning

confidence: 99%

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Evidence for the Role of MAP1B in Axon Formation

González-Billault

Ávila

Cáceres

2001

MBoC

135

141

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Cultured neurons obtained from a hypomorphous MAP1B mutant mouse line display a selective and significant inhibition of axon formation that reflects a delay in axon outgrowth and a reduced rate of elongation. This phenomenon is paralleled by decreased microtubule formation and dynamics, which is dramatic at the distal axonal segment, as well as in growth cones, where the more recently assembled microtubule polymer normally predominates. These neurons also have aberrant growth cone formation and increased actin-based protrusive activity. Taken together, this study provides direct evidence showing that by promoting microtubule dynamics and regulating cytoskeletal organization MAP1B has a crucial role in axon formation. INTRODUCTIONNeurons are highly polarized cells that contain a single long axon and multiple dendrites. Polarization occurs when one of the multiple neurites emerging from the cell body initiates a phase of rapid elongation, becoming the axon; the remaining neurites will develop as dendrites Dotti, 1997, 1999;Dotti et al., 1998). Because microtubule assembly and stabilization play an essential role in axon formation (Mitchison and Kirschner, 1989) a great deal of attention has been devoted to identify factors controlling microtubule organization and dynamics in nerve cells. Current evidence favors the view that several of the distinctive properties of neuronal microtubules, such as increased stability and spatial differentiation, arise from the developmentally regulated expression of structural microtubule-associated proteins (MAPs), which are notably abundant in neurons (Maccioni and Cambiazo, 1995). Therefore, it is likely that the expression of these proteins along neuronal development may affect neuronal polarization.MAP1B (Bloom et al., 1995) is the first MAP that is specifically expressed during neural development and that is especially prominent in neurons that are actively extending axons (Calvert and Anderton, 1985;Garner et al., 1990;Fischer and Romano-Clarke, 1991;Ulloa et al., 1993;Black et al., 1994: DiTella et al., 1996Gordon-Weeks and Fischer, 2000). These findings led to the hypothesis that MAP1B might be involved in axon formation by regulating microtubule dynamics. Evidence in favor of this proposal came from antisense experiments showing that MAP1B suppression reduces laminin-promoted axonal elongation (DiTella et al., 1996) and neurite outgrowth in PC12 cells (Brugg et al., 1993). More recently, it was shown that in Drosophila, an MAP1B-like protein is required for proper axonal and dendritic development Roos et al., 2000), and that microscale chromophore-assisted laser inactivation of phosphorylated MAP1B altered growth cone turning behavior in cultured neurons (Mack et al., 2000). The generation of MAP1B mutant mice has also provided additional important information. Despite discrepancies concerning the severity of the effects, all studies demonstrate that MAP1B-deficient mice have an impairment of brain development (Edelman et al., 1996;Takei et al., 1997; GonzalezBillault et...

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Section: Delayed Axonal Formation and Growth Cone Abnormalities In Cumentioning

confidence: 99%

Section: Generation and Genotyping Of Map1b Mutant Micementioning

confidence: 99%