The Genome of C57BL/6J Eve , the Mother of the Laboratory Mouse Genome Reference Strain.

Isogenic laboratory mouse strains enhance reproducibility because individual animals are genetically identical. For the most widely used isogenic strain, C57BL/6, there exists a wealth of genetic, phenotypic, and genomic data, including a high-quality reference genome (GRCm38.p6). Now 20 years after the first release of the mouse reference genome, C57BL/6J mice are at least 26 inbreeding generations removed from GRCm38 and the strain is now maintained with periodic reintroduction of cryorecovered mice derived from a single breeder pair, aptly named Adam and Eve. To provide an update to the mouse reference genome that more accurately represents the genome of today\u27s C57BL/6J mice, we took advantage of long read, short read, and optical mapping technologies to generate a de novo assembly of the C57BL/6J Eve genome (B6Eve). Using these data, we have addressed recurring variants observed in previous mouse genomic studies. We have also identified structural variations, closed gaps in the mouse reference assembly, and revealed previously unannotated coding sequences. This B6Eve assembly explains discrepant observations that have been associated with GRCm38-based analyses, and will inform a reference genome that is more representative of the C57BL/6J mice that are in use today

Mitochondrial Oxidative Stress Causes Hyperphosphorylation of Tau

Age-related neurodegenerative disease has been mechanistically linked with mitochondrial dysfunction via damage from reactive oxygen species produced within the cell. We determined whether increased mitochondrial oxidative stress could modulate or regulate two of the key neurochemical hallmarks of Alzheimer's disease (AD): tau phosphorylation, and ß-amyloid deposition. Mice lacking superoxide dismutase 2 (SOD2) die within the first week of life, and develop a complex heterogeneous phenotype arising from mitochondrial dysfunction and oxidative stress. Treatment of these mice with catalytic antioxidants increases their lifespan and rescues the peripheral phenotypes, while uncovering central nervous system pathology. We examined sod2 null mice differentially treated with high and low doses of a catalytic antioxidant and observed striking elevations in the levels of tau phosphorylation (at Ser-396 and other phospho-epitopes of tau) in the low-dose antioxidant treated mice at AD-associated residues. This hyperphosphorylation of tau was prevented with an increased dose of the antioxidant, previously reported to be sufficient to prevent neuropathology. We then genetically combined a well-characterized mouse model of AD (Tg2576) with heterozygous sod2 knockout mice to study the interactions between mitochondrial oxidative stress and cerebral Aß load. We found that mitochondrial SOD2 deficiency exacerbates amyloid burden and significantly reduces metal levels in the brain, while increasing levels of Ser-396 phosphorylated tau. These findings mechanistically link mitochondrial oxidative stress with the pathological features of AD

Mitochondrial Oxidative Stress Causes Hyperphosphorylation of Tau

Age-related neurodegenerative disease has been mechanistically linked with mitochondrial dysfunction via damage from reactive oxygen species produced within the cell. We determined whether increased mitochondrial oxidative stress could modulate or regulate two of the key neurochemical hallmarks of Alzheimer’s disease (AD): tau phosphorylation, and ß-amyloid deposition. Mice lacking superoxide dismutase 2 (SOD2) die within the first week of life, and develop a complex heterogeneous phenotype arising from mitochondrial dysfunction and oxidative stress. Treatment of these mice with catalytic antioxidants increases their lifespan and rescues the peripheral phenotypes, while uncovering central nervous system pathology. We examined sod2 null mice differentially treated with high and low doses of a catalytic antioxidant and observed striking elevations in the levels of tau phosphorylation (at Ser-396 and other phospho-epitopes of tau) in the low-dose antioxidant treated mice at AD-associated residues. This hyperphosphorylation of tau was prevented with an increased dose of the antioxidant, previously reported to be sufficient to prevent neuropathology. We then genetically combined a wellcharacterized mouse model of AD (Tg2576) with heterozygous sod2 knockout mice to study the interactions between mitochondrial oxidative stress and cerebral Aß load. We found that mitochondrial SOD2 deficiency exacerbates amyloid burden and significantly reduces metal levels in the brain, while increasing levels of Ser-396 phosphorylated tau. Thes

The Genome of C57BL/6J "Eve", the Mother of the Laboratory Mouse Genome Reference Strain

Isogenic laboratory mouse strains enhance reproducibility because individual animals are genetically identical. For the most widely used isogenic strain, C57BL/6, there exists a wealth of genetic, phenotypic, and genomic data, including a high-quality reference genome (GRCm38.p6). Now 20 years after the first release of the mouse reference genome, C57BL/6J mice are at least 26 inbreeding generations removed from GRCm38 and the strain is now maintained with periodic reintroduction of cryorecovered mice derived from a single breeder pair, aptly named Adam and Eve. To provide an update to the mouse reference genome that more accurately represents the genome of today\u27s C57BL/6J mice, we took advantage of long read, short read, and optical mapping technologies to generate a de novo assembly of the C57BL/6J Eve genome (B6Eve). Using these data, we have addressed recurring variants observed in previous mouse genomic studies. We have also identified structural variations, closed gaps in the mouse reference assembly, and revealed previously unannotated coding sequences. This B6Eve assembly explains discrepant observations that have been associated with GRCm38-based analyses, and will inform a reference genome that is more representative of the C57BL/6J mice that are in use today

The Genome of C57BL/6J “Eve”, the Mother of the Laboratory Mouse Genome Reference Strain

Isogenic laboratory mouse strains enhance reproducibility because individual animals are genetically identical. For the most widely used isogenic strain, C57BL/6, there exists a wealth of genetic, phenotypic, and genomic data, including a high-quality reference genome (GRCm38.p6). Now 20 years after the first release of the mouse reference genome, C57BL/6J mice are at least 26 inbreeding generations removed from GRCm38 and the strain is now maintained with periodic reintroduction of cryorecovered mice derived from a single breeder pair, aptly named Adam and Eve. To provide an update to the mouse reference genome that more accurately represents the genome of today’s C57BL/6J mice, we took advantage of long read, short read, and optical mapping technologies to generate a de novo assembly of the C57BL/6J Eve genome (B6Eve). Using these data, we have addressed recurring variants observed in previous mouse genomic studies. We have also identified structural variations, closed gaps in the mouse reference assembly, and revealed previously unannotated coding sequences. This B6Eve assembly explains discrepant observations that have been associated with GRCm38-based analyses, and will inform a reference genome that is more representative of the C57BL/6J mice that are in use today

APP vs. copper correlation.

<p>Levels of APP and Copper in the soluble and pellet phases of brain homogenate from untreated Tg2576 and Tg2576:<i>sod2</i> crossed mice (pooled) were compared graphically and found to correlate strongly (* p<0.02).</p

Tau phosphorylation sites identified in <i>sod2</i> null mouse brain tissue

<p><b>a</b>: Percent changes of listed residue in <i>sod2</i> null mice relative to <i>sod2</i>wild-types (normalized to 100%, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0000536#pone-0000536-g001" target="_blank">Figure 1</a>), both treated with EUK189 at 1 mg/kg quantitated by Western blotting with monoclonal antibodies for the indicated tau residues, NS– not significant, ND – not done.</p><p><b>b</b>: identifications were positive (+) if a MS/MS spectrum could be unambiguously interpreted to identify a unique phosphorylation site. In three cases (+/−) assignments were based on MS or MS/MS data and alternative sites were possible.</p><p><b>c</b>: several matching phospho peptides observed by ESI-MS (i.e., peptides: mono-/di-phosph. S195-R209 and mono-/di-phosph. S181-R209);</p><p><b>d</b>: Phosphorylate site possibly on Ser-404, Thr-403 or Ser-400;</p><p><b>e</b>: peptide observed with 1P and 2P groups;</p><p><b>f</b>: differences in peptide sequence (human vs. mouse) likely accounting for negative antibody result (homologous human peptide: T<u>P</u>P<u>A</u>PKTPP<u>S</u>SGEPPK);</p><p><b>g</b>: no antibody available for Ser-159.</p

Immunohistochemical identification of phospho-tau positive dystrophic neurites in Tg2576:<i>sod2</i> mice.

<p>(a) Immunohistochemistry for anti Ser-396 was carried out as described in the text, and positivity was observed surrounding senile plaques in the brains of Tg2576:<i>sod2</i> mice. (b) In order to ensure specificity, we also tested the effects of preadsorbing the Ser-396 antibody with the peptide the antibody was raised against. This abolished the staining seen around the plaques.</p

Exacerbation of amyloid load by genetic combination of lack of <i>sod2</i> and overexpression of APP.

<p>(a) Immunohistochemistry quantitation (area occupied by Aß/mm2) did not demonstrate any significant alterations in total Aß plaque burden, although there is an ∼30% increase (p = 0.2) in plaques in the Tg2576:<i>sod2</i> animals as compared to other groups. (b) ELISA quantitation demonstrates that EUK189 treatment significantly modulates Aß levels. Furthermore, genetically combining lack of <i>sod2</i> with overexpression of mutant APP elevates Aß levels in the Tg2576 mouse. The data indicate mean±SD.</p

Mitochondrial oxidative stress results in a synergistic increase in the levels of phospho-tau in Tg2576 mice.

<p>Data show the mean±SD levels of Ser-396 phospho-tau assayed by Western blot of cortical extracts from mice of ≈500 days of age from each of the following genotypes: wild-type n = 4, <i>sod2</i>+/−n = 4, Tg2576 n = 8, Tg2576:<i>sod2</i> n = 9 (all matched for genetic background). A non parametric t test was carried out between genotypes, and a significant increase in phospho tau in the Tg2576:<i>sod2</i> mice was observed, compared to controls.</p