Analysis Tools
behavior/neurological
|
• in the rotarod task, mice show significant deficits in motor performance in terms of best speed, average time, and best time on the cylinder of the unit at 6 months, with gradual worsening seen by 15 months of age
• when subjected to walk on a medium beam, motor performance begins to deteriorate at 9 months, with a significant decline noted by 15 months of age
|
 |
IMPC - JAX
|
cellular
microgliosis
(
J:376327
)
|
• at 18 months of age, affected brain regions show increased aggregation of reactive microglia, not present in age-matched wild-type controls
• reactive microglia are closely associated with abnormal large RTN3 immunoreactive aggregates; in contrast, most spheroids of small or medium size are spared from reactive microglia
• swollen dopaminergic axonal terminals interact with reactive microglia in the striatum, while such microglia reactivity is less prevalent in the substantia nigra
|
|
• abnormal spheroids consist of abnormal expansions of smooth ER membranes in the brain, especially in axonal terminals of dopaminergic neurons
• at 4 months of age, anti-RTN3 antibody-stained ER membranes aggregate in the brainstem
• by 18 months, widespread RTN3 aggregations are detected in the brainstem, hippocampus, substantia nigra, and striatum
|
|
• axonal spheroids are associated with abnormal ER and damaged mitochondria
|
|
• double immunofluorescence staining with anti-RTN3 and anti-PDHE1 for tubular ER and mitochondria respectively, showed enlarged abnormal mitochondria around anti-RTN3 lucent clefts of axonal spheroids
|
|
• aged mice show disturbed tubular ER homeostasis in the brain; at 12 months of age, proteins involved in tubular ER network organization (ARL6IP1, ATL1 and REEP5) are significantly increased while other tubular ER proteins including RTN3 are mildly skewed toward higher expression
• abnormal spheroids consistently contain the tubular ER protein reticulon 3 (RTN3) even at younger ages, before the onset of motor symptoms
|
hematopoietic system
microgliosis
(
J:376327
)
|
• at 18 months of age, affected brain regions show increased aggregation of reactive microglia, not present in age-matched wild-type controls
• reactive microglia are closely associated with abnormal large RTN3 immunoreactive aggregates; in contrast, most spheroids of small or medium size are spared from reactive microglia
• swollen dopaminergic axonal terminals interact with reactive microglia in the striatum, while such microglia reactivity is less prevalent in the substantia nigra
|
homeostasis/metabolism
|
• at 18 months of age, affected brain regions (cerebellum, cuneate, striatum, and thalamus) show increased levels of redox iron by modified Prussian Blue staining
• real-time PCR analysis of iron metabolism genes indicates upregulation of Fpn1, Mfrn1, Mfrn2, Fth1, Ftl1, Abcb7, and Trfc2 in the brain, suggesting disturbed iron metabolism
|
immune system
microgliosis
(
J:376327
)
|
• at 18 months of age, affected brain regions show increased aggregation of reactive microglia, not present in age-matched wild-type controls
• reactive microglia are closely associated with abnormal large RTN3 immunoreactive aggregates; in contrast, most spheroids of small or medium size are spared from reactive microglia
• swollen dopaminergic axonal terminals interact with reactive microglia in the striatum, while such microglia reactivity is less prevalent in the substantia nigra
|
|
• aged mice show widespread neuroinflammation in affected brain tissues
|
integument
|
|
IMPC - JAX
|
nervous system
microgliosis
(
J:376327
)
|
• at 18 months of age, affected brain regions show increased aggregation of reactive microglia, not present in age-matched wild-type controls
• reactive microglia are closely associated with abnormal large RTN3 immunoreactive aggregates; in contrast, most spheroids of small or medium size are spared from reactive microglia
• swollen dopaminergic axonal terminals interact with reactive microglia in the striatum, while such microglia reactivity is less prevalent in the substantia nigra
|
|
• at 18 months of age, affected brain regions (cerebellum, cuneate, striatum, and thalamus) show increased levels of redox iron by modified Prussian Blue staining
• real-time PCR analysis of iron metabolism genes indicates upregulation of Fpn1, Mfrn1, Mfrn2, Fth1, Ftl1, Abcb7, and Trfc2 in the brain, suggesting disturbed iron metabolism
|
|
• aged mice show widespread neuroinflammation in affected brain tissues
|
|
• EM shows abnormal mitochondria and ER arranged with tubulovesicular structures in swollen axons in the cuneate nucleus
|
|
• EM shows tubulovesicular structures, long condensed membranes, and electron-lucent clefts in swollen axons in the striatum
• however, no striking axon terminal loss is observed in the striatum
|
|
• EM shows spiral layers of smooth ER membranes containing autophagic vesicles in the center, along with nearby damaged mitochondria, in the cerebellum
|
|
• at 18 months of age, a significant loss of Purkinje cells is noted in the cerebellum
|
|
• at 18 months of age, stereological analysis shows a marked decrease in the cell size of TH neurons but no change in the number of TH neurons in the substantia nigra
• axonal swellings in dopaminergic neurons contain pathological protein inclusions (alpha-synuclein and ubiquitin)
|
|
• dopaminergic neurons exhibit swollen axon terminals
|
|
• alpha-synuclein inclusions are identified in dopaminergic neurons, especially within TH swollen axons in the striatum
• alpha-synuclein pathology is not restricted to anti-TH positive dopaminergic neurons
|
|
• aged mice develop neuroaxonal dystrophy by 18 months of age
• however, no differences are observed in the birth rate or overall development
|
|
• at 18 months of age, all brains exhibit numerous axonal spheroids; spheroid bodies are eosinophilic, of variable size and morphology, contain lucent clefts, and are found in the cerebellum nucleus, thalamus, pons, spinal cord and cuneate
• abnormal spheroids consistently contain the tubular ER protein reticulon 3 (RTN3) even at younger ages, prior to the onset of motor symptoms
• abnormal tubular ER and mitochondria are the major components of swollen axons which are likely to expand longitudinally to no more than 20 um
• anti-RTN3 antibody decorates three types of spheroids based on size: large spheroid aggregates (type I), medium-sized spheroids with lucent clefts (type II), and small spheroids associated with regular axon size (type III)
• small type III spheroids can be identified by common ER markers (anti-IP3R and anti-calnexin antibodies); co-immunostaining of RTN3 with other tubular ER proteins (REEP2 and REEP5) shows their co-localization in large type I and type II swollen axons
• further analysis of anti-RTN3 shows co-localization with the axonal marker beta-III-tubulin
|
|
• age-dependent accumulation of neuroaxonal swellings likely results in impaired dopaminergic system function in the substantia nigra, striatum, and other brain regions, leading to motor function deficits
• however, no changes are apparent in the hippocampus or cortical brain structures, and brain weight is not significantly altered even at 18 months of age, suggesting a more chronic condition rather than acute neuronal death throughout the brain
|
pigmentation
|
|
IMPC - JAX
|
Mouse Models of Human Disease |
DO ID | OMIM ID(s) | Ref(s) | |
| neurodegeneration with brain iron accumulation 4 | DOID:0110738 |
OMIM:614298 |
J:376327 | |
