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K Herrup

Publications and source records attributed to K Herrup.

90 records · Page 5Linked to original sources
PubMed1983

Role of staggerer gene in determining cell number in cerebellar cortex. I. Granule cell death is an indirect consequence of staggerer gene action.

Mouse chimeras were made by aggregating two embryos at the 8-cell stage of development. These experimental mosaic animals are useful in assessing whether the effect of a mutant gene in a given cell type is direct (intrinsic) or indirect (extrinsic). The results reported are an analysis of the involvement of the staggerer gene in the phenotype of granule cell death observed in staggerer mutant mice. The ichthyosis mutation has been used as an independent cell marker. This mutation produces no known neurological defects but does cause a characteristic clumping of heterochromatin, especially in small cells. Analysis of two staggerer in equilibrium ichthyosis chimeras leads to the conclusion that staggerer granule cells, that would have died in the mutant, are rescued in the mosaic cerebella. The death of granule cells in the homozygous staggerer mutant is thus an indirect, epigenetic consequence of direct gene action in other cells. The implications and limitations of this conclusion are discussed.

Animals↗
PubMed1982

Interaction of granule, Purkinje and inferior olivary neurons in lurcher chimeric mice. II. Granule cell death.

Lurcher in equilibrium ichthyosis chimeric mice were constructed to determine whether the death of cerebellar granule cells in lurcher mutants is caused by intrinsic or extrinsic factors. Quantitative analysis demonstrates that more lurcher granule cells survive in the chimeras than would have in the mutants themselves. Thus the granule cell death is an indirect consequence of the lurcher gene acting on some other cell type, probably the cerebellar Purkinje cells.

Animals↗
PubMed1982

Cerebellar cell degeneration in the leaner mutant mouse.

Leaner is an autosomal recessive mutation of the mouse which results in a severe ataxia accompanied by cellular losses in the cerebellar cortex. The purpose of this report is to construct a developmental profile of these losses. Of the three cerebellar cell types studied, the granule cells are the first to show obvious degenerative changes. Pycnotic cells are numerous in the internal granule cell layer at postnatal day 10, and, while they are found throughout the cortex, they are more concentrated in the anterior folia. Initially, there is a strong tendency for the pycnotic cells to be located in the deep half of the internal granule cell layer. By four postnatal months the rate of loss has slowed but the finding of occasional pycnotic cells in animals up to one year old suggests it continues for the life of the animal. Quantitative analysis of Purkinje and Golgi cells in leaner cerebella reveals a progressive loss of these cells as well. The number of Golgi cells falls uniformly to around half of the wild-type number. By contrast, the Purkinje cells show much more extensive degeneration. Further, the rate of cell death shows a regional variation; it is significantly more rapid in anterior folia. Overall, the number of Purkinje cells in leaner falls to about one-fifth of the wild-type number. The loss of both Purkinje and Golgi cells occurs late relative to the major events of cerebellar maturation. Significant cell loss is not observed until the end of the first postnatal month. For the next 4 to 6 weeks there is extensive cell death but, rather than abating, it appears to continue at a low rate for the life of the animal. It is hoped that this developmental sketch of the leaner defect will stimulate others to approach leaner and its alleles, tottering and rolling, as models for heterogeneity of disease expression.

Aging↗
PubMed1982

Interaction of granule, Purkinje and inferior olivary neurons in lurcher chimaeric mice. I. Qualitative studies.

Heterozygous lurcher (+/Lc) mutant mice lose 100% of their Purkinje cells (PCs), 90% of their granule cells, and 75% of their inferior olivary neurons. In order to determine the primary site of Lc gene action, lurcher in equilibrium wild-type aggregation chimaeras were produced. The cerebella of the three chimaeras examined were intermediate or normal in size compared to +/Lc and wild-type cerebella. The PCs were reduced in number. Using the beta-glucuronidase locus (Gus) as a cell marker, all of the PCs present were identified as having descended from the wild-type embryo. It appears that all of the +/Lc PCs degenerated. Hence, the Lc gene acts directly on PCs to cause their degeneration. The inferior olivary nuclei of the chimaeras seemed to have fewer neurons than wild-type but more than +/Lc animals. As revealed by beta-glucuronidase histochemistry, both +/+ and +/Lc cells were present, and the ratio of genotypes was similar to the ratio seen in other regions of the brain. The evidence suggests that the death of olivary neurons in lurcher is secondary to another defect, probably the loss of PCs. Beta-glucuronidase is not an accurate cell marker for granule cells, and so no conclusion concerning the action of the Lc gene on granule cells could be made with these chimaeras.

Animals↗
PubMed1982

Cerebellar Purkinje cells are descended from a small number of progenitors committed during early development: quantitative analysis of lurcher chimeric mice.

Previous analysis of lurcher in equilibrium wild type aggregation chimeras revealed that the degeneration of cerebellar Purkinje cells (PCs) in lurcher mutants is due to a defect intrinsic to the PCs themselves. Thus, all of the PCs remaining in lurcher chimeric mice are descended from only the wild type embryo. In this study, we have determined the number of PCs in four lurcher chimeras and three wild type mice. The low number of wild type PCs (10,200) in half of the cerebellum of one chimera (chi 11) suggested that these cells might be descended from a single progenitor. This idea is strongly supported by the quantitative analysis of the PCs in the other animals. These numbers are integral multiples of the number of PCs in chi 11. We believe that each stepwise increase in the number of PCs in the chimeras is due to the addition of a single wild type cell to the progenitor pool. The existence of integral multiples implies that no other cells can contribute to the PC population after the progenitors become committed to forming PCs. We cannot know, however, whether the PC progenitors also give rise to other cell populations. The values of the integrals in wild type mice indicate that the entire PC population descends from a small number of progenitors (8 in C3H/HeJ mice). We calculate that these progenitors are committed during the neural plate to neural fold stage of development. Thus, the fate of the progenitors of the cerebellar PCs is restricted very early in neural development.

Aging↗
PubMed1981

Quantitative examination of the deep cerebellar nuclei in the staggerer mutant mouse.

Quantitative morphological techniques have revealed several new aspects of the action of the Staggerer mutant gene. Staggerer is an autosomal recessive gene which causes ataxia and severe malformation of the cerebellar cortex in mice. The Purkinje cells of the cerebellar cortex are small, abnormal in morphology and reduced in numbers. The close synaptic and developmental relationship of Purkinje cells with the cells of the deep cerebellar nuclei (dcn) lead us to look for effects of the Staggerer mutation on the dcn neurons. The volume of the deep nuclear region is shrunken in Staggerer and there is a reduction in the volume of the white matter. These findings account for the reduced wet weights and protein concentration found by Roffler-Tarlov and Sidman. In contrast to the cells of the cortex, where 75% of the medium-to-large neurons are missing, the number of cells present in Staggerer dcn is identical to wild-type. The dcn neurons are not completely spared, however. Measurements of cross-sectional cell area revealed a 30% shrinkage of neurons in Staggerer dcn. The most likely interpretation of previous work and the current findings is that the Staggerer gene acts early in development but exerts its effects directly only on those derivatives of the ventricular zone in the roof of the fourth ventricle which are destined to become Purkinje and Golgi cells.

Animals↗
PubMed1981

Role of the Staggerer gene in determining Purkinje cell number in the cerebellar cortex of mouse chimeras.

Staggerer (sg) is a mutation in mice which causes severe cerebellar atrophy. Virtually all of the granule cells degenerate by the end of the first postnatal month. The Purkinje cells are also affected. They are reduced in number, ectopic in location, reduced in size and show a regional variation in their cytological appearance. The appearance of the cerebellar cortex of Staggerer in equilibrium wild-type chimeric mice has demonstrated that the reduced size, ectopia, and regional variation are always traits of cells whose nucleus is of sg/sg genotype and thus are due to factors intrinsic to the affected cell. This report is a quantitative analysis of the cerebellar cortex of two Staggerer chimeras. Sections were chosen from serially sectioned half cerebella. Using beta-glucuronidase activity as an independent marker of a cell's genotype, cells were scored as belonging to 1 of 3 cell classes: wild-type Purkinje cell, wild-type Golgi cell, and Staggerer medium-to-large neuron. The results confirm that the total number of cells in the chimera (all 3 classes) is greater than that found in a homozygous Staggerer but less than that found in a wild-type. Further, the distribution of the two genotypes strongly suggests that the decreased number of cells in Staggerer and in the chimera is due to an intrinsic defect in the Staggerer cells and not to a general (extrinsic) compromising of cerebellar development. Possible implications for normal cerebellar development are discussed.

Animals↗
PubMed1979

Staggerer chimeras: intrinsic nature of Purkinje cell defects and implications for normal cerebellar development.

The site of gene action of the Staggerer mutation of mice was investigated with Staggerer in equilibrium or formed from wild-type chimeras. Homozygous Staggerer mice show severe locomotor difficulties due to cerebellar abnormalities which include degeneration of virtually all granule cells and cytological defects in Purkinje cells. Although the locomotor deficits of the mutant were not present in the chimeras, the presence of Staggerer cells affected cerebellar structure. The size and the extent of foliation of the chimeric cerebella were intermediate between wile-type and homozygous Staggerer. A normally proportioned granule cell layer was present. Using beta-glucuronidase as an independent determinant of a cell's genotype, it was found that the genotypically Staggerer medium-to-large neurons expressed all of the light microscopic defects observable in these cells in the homozygous mutant. These defects include: (1) smaller size; (2) usually ectopic location; and (3) regional variation in the cytological appearance of the perikaryon. By contrast, all Purkinje cells which were genotypically wild-type appeared normal in size, in location and in their cytological appearance. Their density, however, was much reduced from wild-type. The effects of the Staggerer mutation on the granule, stellate and basket cells could not be directly assessed as the glucuronidase marker is not suitable for use with these cells. The Staggerer gene thus acts directly on Purkinje cells rather than via extracellular environmental changes. The findings are discussed in terms of their implications for normal cerebellar development.

Animals↗
PubMed1979

Regional variation and absence of large neurons in the cerebellum of the staggerer mouse.

Staggerer (sg) is a neurological mutant mouse in which the cerebellar granule cells degenerate after migration to the internal granule cell layer. In addition, the Purkinje cells are abnormal, being ectopic, smaller in size and without tertiary branchlet spines. In this study we report two new observations on this mutant: (1) the effects of the mutation show a regional variation in severity along the mediolateral axis. This variation is seen in the cross-sectional size of the tissue, the extent of cortical folding, as well as the density and cytological appearance of the medium-to-large cortical neurons (MLNs); (2) cell counts were done of 30-day-old mutants and of wild-type controls. The counts revealed that three-quarters of the MLNs of the cerebellar cortex are missing in staggerer. These findings cannot exclude the possibility that Golgi as well as Purkinje cells are absent since the two cannot be distinguished in staggerer. Depending on the number of Golgi cells present, between 60% and 90% of the wild-type number of Purkinje cells is missing in staggerer. The results are discussed in terms of their implications for other studies and for locating the site of staggerer gene action.

Animals↗
PubMed1979

Intercellular transfer of beta-glucuronidase in chimeric mice.

Chimeric mice were produced by aggregating 2 embryos, each of which was homozygous for a different structural allele of the enzyme beta-glucuronidase. The alleles used were Gusb, the 'wild-type' allele, and Gush, an allele whose gene product shows decreased activity in all tissues as well as decreased heat stability. Staining of untreated adult chimeric livers for glucuronidase activity revealed a mosaic of high (Gusb) and low (Gush) activity cells. The boundaries between cells of different activity were sharp and revealed no diffusion of enzyme or reaction product. Treating sections at 73 degrees c before staining led to a decay of staining activity in normal (non-chimeric) Gush/Gush and Gusb/Gusb tissue. The rates of activity loss under the conditions used differed by 10-fold. Of the 2 genotypes in the chimera, the dark-staining, Gusb, cells decayed in a fashion similar to that of the Gusb/Gusb control. The light-staining, Gush, cells of the chimera lost their staining a a unique fashion. Within 20 min they quickly lost a majority of their staining activity but that which remained was relatively heat stable. The second Gusb-like phase of the decay, seen both photographically and photometrically, suggests that Gusb gene product has been transferred to cells of Gush/Gush genotype.

Alleles↗
PubMed1977

Biochemical and genetic factors in the heat inactivation of murine beta-glucuronidase.

The enzymes coded for by two alleles at the glucuronidase structural locus (Gus) were compared in their response to pH, buffering anion, buffer molarity, ionic strength, and temperature. The heat-labile Gush gene product responded in a qualitatively similar but quantitatively reduced manner compared to the relatively heat-stable Gusb gene product. In all buffers tested, the enzyme was most heat stable at pH 5.0. Ranking of the various buffer anions tested, according to increasing heat stabilization, was water less than acetate less than or equal to phosphate less than citrate. Varying the molarity of the buffers from 0.01 to 0.6 M at pH 5.0 revealed further differences among the buffers. Increasing ionic strength exerted a destabilizing force on the protein. The half-life of the enzyme decreased by as much as a hundredfold between 71 and 75 C. The Gush/Gush genotype also results in decreased activity levels in all tissues, reportedly because of decreased synthesis. The heat inactivation curves of Gusb/Gush heterozygotes were incompatible with any theoretical curve based on the assumption that the Gusb and Gush chromosomes in the heterozygote behave in a manner similar to that seen in the homozygotes.

Alleles↗
PubMed1976

Comparison of the nerve growth factor proteins from cobra venom (Naja naja) and mouse submaxillary gland.

The nerve growth factors (NGF's) isolated from cobra venom (Naja naja) and mouse submaxillary gland are closely related proteins. They are structurally similar in that about 60% of their amino acid residues are identical (Hogue-Angeletti, R. A., Frazier, W. A., Jacobs, J. W., Niall, H.D., and Bradshaw, R. A. (1976), Biochemistry, preceding paper in this issue). They are functionally similar in that they both elicit maximum neurite outgrowth from chick embryonic dorsal root ganglia at the same protein concentration. However, the extent of the response is not as great with Naja naja NGF. The cobra NGF has an affinity close to that of mouse NGF for a major proportion of the specific NGF receptors on cells from dissociated embryonic dorsal root ganglia. Despite these similarities there are differences which can be detected between the two proteins. High concentrations of Naja naja NGF will not displace approximately 20% of the binding of mouse NGF to specific NGF receptors. Moreover, Naja naja NGF shows limited cross-reactivity with antiserum to mouse NGF in a competition radioimmunoassay, consistent with the extent of its amino acid sequence homology with mouse NGF. Naja naja NGF does not interact with the alpha- and gamma-subunits of 7S NGF to form a high molecular weight complex. In this behavior it resembles a modified form of mouse NGF which, like Naja naja NGF, lacks COOH-terminal arginine residues.

Amino Acids↗
PubMed1975

Properties of the beta-nerve growth factor receptor in development.

The cell surface receptor for beta-nerve growth factor was used as a probe to study the development of embryonic chick sensory ganglia. The ganglia were shown to lose their responsiveness to nerve growth factor in vitro between 14 and 16 days of embryonic age. This loss occurred by a decrease in the magnitude of the maximum biological response, not by a shifting of the response to higher concentrations. Binding assays for the beta-nerve growth factor receptor, using 125I-radiolabelled beta-nerve growth factor, were performed with cells from sensory ganglia 8, 12, 14, 16, 18, and 21 days of age. The assays revealed a twofold increase in the number of receptor sites per ganglion between 8 and 14 days and a sixfold drop between 14 and 16 days of embryonic life. Neither increase nor decrease was accompanied by a large change in the affinity of the receptor for the protein. Together with the results of the bioassay, the data show that the loss of biological responsiveness is correlated with and may be due to a loss of the cells' ability to bind beta-nerve growth factor. Correlation of the results of the binding assays with the known ontogeny of the chick embryo provides a hint at the role of nerve growth factor in normal development.

Animals↗
PubMed1973

Properties of the beta nerve growth factor receptor of avian dorsal root ganglia.

Iodination of the beta nerve growth factor protein up to 4.1 iodines per mole of nerve growth factor was achieved with no loss of biological activity. At this level of incorporation no native or monoiodo nerve growth factor remained, the major species being the tri- and tetraiodo derivatives. An (125)I-labeled beta nerve growth factor of high specific activity containing 0.5 iodine per mole of beta nerve growth factor was used to determine the specific binding of nerve growth factor to dorsal root ganglion cells of 8-day-old embryonic chicks. The specific binding of (125)I-labeled nerve growth factor reached saturation at 30-50 ng/ml and half-saturation at 7-8 ng/ml (0.26 nM). The number of receptors per responsive medio-dorsal cell was calculated to be about 2 x 10(4). The pattern of displacement of bound (125)I-labeled beta nerve growth factor by native beta nerve growth factor showed that the two proteins had identical affinities for the receptor. The specificity of the binding for beta nerve growth factor was demonstrated by the fact that only native beta nerve growth factor displaced the bound (125)I-labeled form. Partially inactivated derivatives of beta nerve growth factor retained the same fraction of their specific-binding capacity as of their biological activity. The specificity of the binding for cell type was shown by the lack of any specific component of (125)I-labeled beta nerve growth factor binding to liver or brain cells. The rate constant for association of beta nerve growth factor with its receptor, k(1), was 1.0 x 10(7) mol(-1) sec(-1) and the rate constant for dissociation, k(-1), 1.2 x 10(-8) sec(-1).

Animals↗
PubMedDate not supplied

Beta-amyloid activated microglia induce cell cycling and cell death in cultured cortical neurons.

Immunocytochemical studies of postmortem human tissue have shown that the neurons at risk for degeneration in Alzheimer's are marked by the ectopic expression of several cell cycle components. The current work investigates the roles that beta-amyloid activated microglia might play in leading neurons to re-express cell cycle components. Stable cultures of E16.5 mouse cortical neurons were exposed to beta-amyloid alone, microglial cells alone, or microglial cells activated by beta-amyloid. Increased cell death was found in response to each of these treatments, however, only the amyloid activated microglial treatment increased the number of neurons that were positive for cell cycle markers such as PCNA or cyclin D and incorporation of BrdU. Double labeling with BrdU and TUNEL techniques verified that the 'dividing' neurons were dying, most likely through an apoptotic mechanism. The identity of the soluble factor(s) elaborated by the microglia remains unknown, but FGF2, a suspected neuronal mitogen, was ruled out. These results further support a model in which microglial activation by beta-amyloid is a key event in the progression in Alzheimer's disease.

Amyloid beta-Peptides↗