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Phenotypes associated with this allele
Allele Symbol
Allele Name
Allele ID
Actn4tm1Mrpk
targeted mutation 1, Martin R Pollak
MGI:2664917
Summary 1 genotype
Jump to Allelic Composition Genetic Background Genotype ID
hm1
Actn4tm1Mrpk/Actn4tm1Mrpk involves: 129 * C57BL/6 MGI:2669775


Genotype
MGI:2669775
hm1
Allelic
Composition
Actn4tm1Mrpk/Actn4tm1Mrpk
Genetic
Background
involves: 129 * C57BL/6
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Actn4tm1Mrpk mutation (0 available); any Actn4 mutation (137 available)
phenotype observed in females
phenotype observed in males
N normal phenotype

Focal and segmental glomerulosclerosis in Actn4tm1Mrpk/Actn4tm1Mrpk kidneys over 10 weeks of age

mortality/aging
• mice surviving past the perinatal stage die by several months of age
• fewer homozygous mice are born than expected (about 10% rather than 25%)
• in lethal embryos and neonates, no gross or histological abnormalities are noted

growth/size/body
• weight loss beginning after ~6 weeks of age
• growth rate of homozygotes begins to slow at ~6 weeks of age

renal/urinary system
• areas of glomerular capillary collapse in some homozygous mice at 4 weeks of age
• in a cell culture system, differentiated mutant podocytes are less adherent than wild-type cells to GBM components collagen IV (2.7-fold decrease) and laminin 10/11 (3.1-fold decrease)
• when subjected to high shear stress via fluid flow, mutant podocytes are markedly less adherent to a collagen I substrate than rescued podocytes stably transfected with Actn4-GFP; the % of mutant cells remaining adherent after flow is 6.5% versus 80% for rescued cells, with mutant cells detaching at a lower shear stress than rescued cells
• in response to an applied force, mutant podocytes exhibit 4-fold more bead displacement than wild-type cells by magnetic pulling cytometry, suggesting weaker integrin-cytoskeleton linkages
• decreased podocyte adhesion is not due to changes in cell death or proliferation
• podocyte markers detected in urine as early as 8 days of age, indicating podocyte detachment in vivo
• urinary WT1 protein detected in 75% and 83% of homozygous mice at 1 week and at 6-10 weeks of age, respectively, never seen in wild-type controls
• urinary podocin detected in a subset of urine samples
• all mice exhibiting podocyturia show some degree of proteinuria and vice versa
• increasing albuminuria with advancing age (J:83911)
• significantly increased albumin/creatinine ratios both at 1-2 weeks and at 6-10 weeks of age, unlike in wild-type controls (J:118122)
• podocyturia and albuminuria appear to develop concurrently (J:118122)
• mild microalbuminuria in most but not all homozygous mice at sacrifice (5.5 weeks of age)
• mild disruption of podocyte structure with areas of focal foot process effacement at 10 days of age
• more extensive foot process effacement by 10 weeks of age
• however, slit diaphragms appear normal
• podocyte number per glomerulus is decreased by 9.9% at 8-9 days of age, and by 18.8% at 6-10 weeks of age
• areas with duplications ("blebs") on the subepithelial aspect of the GBM in some mice at 5 weeks of age
• evidence of focal and segmental glomerulosclerosis in most homozygous mice by 10 weeks of age
• kidneys are typically small by 10 weeks of age
• dilated tubules with disrupted architecture by 10 weeks of age
• dilated tubules are filled with proteinaceous material by 10 weeks of age
• kidneys are typically pale by 10 weeks of age
• eventual kidney failure

homeostasis/metabolism
• increased BUN levels in many but not all homozygous mice at 5.5 weeks of age
• increasing albuminuria with advancing age (J:83911)
• significantly increased albumin/creatinine ratios both at 1-2 weeks and at 6-10 weeks of age, unlike in wild-type controls (J:118122)
• podocyturia and albuminuria appear to develop concurrently (J:118122)
• mild microalbuminuria in most but not all homozygous mice at sacrifice (5.5 weeks of age)

cellular
• in a cell culture system, differentiated mutant podocytes are less adherent than wild-type cells to GBM components collagen IV (2.7-fold decrease) and laminin 10/11 (3.1-fold decrease)
• when subjected to high shear stress via fluid flow, mutant podocytes are markedly less adherent to a collagen I substrate than rescued podocytes stably transfected with Actn4-GFP; the % of mutant cells remaining adherent after flow is 6.5% versus 80% for rescued cells, with mutant cells detaching at a lower shear stress than rescued cells
• in response to an applied force, mutant podocytes exhibit 4-fold more bead displacement than wild-type cells by magnetic pulling cytometry, suggesting weaker integrin-cytoskeleton linkages
• decreased podocyte adhesion is not due to changes in cell death or proliferation
• podocyte markers detected in urine as early as 8 days of age, indicating podocyte detachment in vivo
• urinary WT1 protein detected in 75% and 83% of homozygous mice at 1 week and at 6-10 weeks of age, respectively, never seen in wild-type controls
• urinary podocin detected in a subset of urine samples
• all mice exhibiting podocyturia show some degree of proteinuria and vice versa
• significant increase in baseline and SDF-1-induced lymphocyte chemotaxis relative to wild-type controls

cardiovascular system
• areas of glomerular capillary collapse in some homozygous mice at 4 weeks of age

immune system
• significant increase in baseline and SDF-1-induced lymphocyte chemotaxis relative to wild-type controls

hematopoietic system
• significant increase in baseline and SDF-1-induced lymphocyte chemotaxis relative to wild-type controls

Mouse Models of Human Disease
DO ID OMIM ID(s) Ref(s)
focal segmental glomerulosclerosis 1 DOID:0111128 OMIM:603278
J:83911





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last database update
11/12/2024
MGI 6.24
The Jackson Laboratory