PrP-hFUS*R495X transgenic line PX78 has expression of a truncated mutant form of fused in sarcoma protein that is directed to brain and spinal cord (CNS neurons and astrocytes) by the mouse prion protein promoter. The hFUS*R495X mutation in the nuclear-localization domain is associated with significant cytoplasmically-mislocalized hFUS and amyotrophic lateral sclerosis (ALS). These mice may be useful in studying neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS; Lou Gehrig's Disease) and frontotemporal lobar degeneration (FTLD).
Lawrence J Hayward, University of Massachusetts Medical School
Nucleo-cytoplasmic shuttling of fused in sarcoma (FUS) occurs by a nuclear localization signal (NLS). The majority of clinical amyotrophic lateral sclerosis (ALS; Lou Gehrig's Disease) and frontotemporal lobar degeneration (FTLD)-associated FUS mutations occur in its C-terminal NLS sequence.
The PrP-hFUS*R495X transgene has the mouse prion protein (PrP) promoter directing expression of an ALS-associated human R495X truncation mutant (hFUS*R495X) lacking its C-terminal NLS; resulting in significant hFUS mislocalization (abnormal accumulation within the cytoplasm).
The phenotype description below describes FVB-backcrossed PrP-hFUS*R495X mice from founder line PX78. In an attempt to offer transgenic models on well-characterized or multiple genetic backgrounds, transgenes are frequently moved to a genetic background different from that on which they were first characterized. This is the case for the C57BL/6J-congenic PrP-hFUS*R495X transgenic line PX78 (Stock No. 019728). It should be noted that the phenotype could vary from that described below. We will modify the strain description if necessary as published results become available.
The donating investigator reports that hemizygous mice are viable and fertile, with cytoplasmic mislocalization of hFUS*R495X (as shown by immunostaining with a hFUS-specific antibody). Hemizygous mice have ~10-12 copies of the transgene, with ~4-fold greater hFUS expression levels in brain and spinal cord compared to endogenous mouse FUS levels.
In addition, robust cytoplasmic accumulation of hFUS is reported in cortical neurons, deep cerebellar nuclei, lumbar spinal cord anterior horn cells and hippocampal neurons.
Surprisingly, neurons more than one year old appear to tolerate the cytoplasmic hFUS without evidence of abnormal morphological features or obvious neuronal loss. No inclusions are reported (via FUS immunohistochemistry, ubiquitin markers or p62 markers), and cytoplasmic hFUS expression is not shown to alter the normal nuclear prominence of TDP-43 staining. By 8-12 months, hemizygous mice can exhibit neuropathological/electromyographical abnormalities in hindlimb muscles (fibrillation potentials, muscle denervation and reduction in motor unit number estimation).
Hemizygotes sporadically develop a swollen large intestine and evidence of paralytic ileus that cause premature lethality (50% of the original cohort died by ~118 days of age). Homozygous mice were more severely affected, with lower body mass and earlier premature lethality (50% of the original cohort lost by ~59 days of age).
The PrP-hFUS*R495X transgene was designed by Dr. Lawrence J. Hayward (University of Massachusetts Medical School). First, a cDNA sequence was obtained encoding the human fused in sarcoma R495X truncation mutant (hFUS*R495X) that is associated with amyotrophic lateral sclerosis (ALS). The hFUS*R495X mutation abrogates a putative nuclear localization signal at the C-terminus of FUS, resulting in significant hFUS mislocalization within the cytoplasm. The hFUS*R495X cDNA sequence was inserted between exon 2 and exon 3 of mouse prion protein (PrP or Prnp) gene at two unique XhoI sites in the MoPrP.Xho plasmid (ATCC#JHU-2). The ~13.6 kbp linearized PrP-hFUS*R495X transgene was microinjected into (C57BL/6 x SJL)F2 hybrid mouse embryos at UMass Transgenic Animal Modeling Core facility. Transgenic founders were bred to FVB mice, and founder line PX78 was identified with 10-12 copies of the transgene. These PrP-hFUS*R495X transgenic mice were bred with FVB mice for at least four generations. Next, transgenic mice were bred to C57BL/6J for one generation, and then sent to The Jackson Laboratory Repository in 2013. Upon arrival, transgenic mice were backcrossed with C57BL/6J inbred mice (Stock No. 000664) for at least eight additional generations. The C57BL/6J-congenic PrP-hFUS*R495X transgenic line PX78 is Stock No. 019728.
|Expressed Gene||FUS, fused in sarcoma , human|
|Site of Expression|
|Allele Name||transgene insertion 78, Lawrence Hayward|
|Allele Type||Transgenic (Inserted expressed sequence, Humanized sequence)|
|Allele Synonym(s)||FUSR495X; line PX78|
|Gene Symbol and Name||Tg(Prnp-FUS*R495X)78Ljh, transgene insertion 78, Lawrence Hayward|
|Promoter||Prnp, prion protein, mouse, laboratory|
|Expressed Gene||FUS, fused in sarcoma , human|
|Strain of Origin||(C57BL/6 x SJL)F2|
|Molecular Note||The transgenic construct contains a cDNA sequence encoding the human fused in sarcoma R495X truncation mutant (hFUS*R495X) associated with amyotrophic lateral sclerosis (ALS). The cDNA sequence was inserted between exon 2 and exon 3 of mouse prion protein (PrP or Prnp) gene. The mutation abrogates a putative nuclear localization signal at the C-terminus of FUS, resulting in significant hFUS mislocalization within the cytoplasm. Line PX78 is identified with 10-12 copies of the transgene and results in a 3-5-fold FUS overexpression.|
Transgenic mice were bred to C57BL/6J inbred mice (Stock No. 000664) for at least eight generations to establish this congenic strain. When maintaining the live congenic colony, hemizygous mice may be bred with wildtype (noncarrier) mice from the colony or with C57BL/6J mice.
When using the PrP-hFUS(R495X) line PX78 mouse strain in a publication, please cite the originating article(s) and include JAX stock #019728 in your Materials and Methods section.