Animal Models for Disease: Knockout, Knock-In, and Conditional Mutant Mice

Abstract F-box and WD-40 domain protein 7 (Fbxw7) is a component of the Skp1-Cdc53/Cullin-F-box-protein complex (SCF/β-TrCP), which is an E3 ubiquitin ligase that mediates protein degradation. This complex has recently been shown to negatively regulate spermatogonial stem cell self-renewal; however, its roles in Sertoli cell (SC) proliferation, differentiation, and function remain to be established. In this study, we generated conditional mutant mice with SC-specific deletion of Fbxw7 via the Cre-loxP system. Fbxw7 deficiency in SCs impaired testis development, which is characterized by age-dependent tubular atrophy, excessive germ cell loss, and spermatogenic arrest, and the mutant males were infertile at 7 months old. Fbxw7 ablation also compromised cytoskeletal organization and cell polarity of SCs, as well as integrity of the blood-testis barrier. In addition, the transcript levels of cell markers for germ cells, Leydig cells, and SCs were significantly decreased in Fbxw7 mutant mice. Importantly, protein levels of GATA-4, a transcription factor that plays a crucial role in SC maturation and testis development, were progressively decreased in control SCs after postnatal day 14, whereas levels were aberrantly elevated in Fbxw7-deleted SCs. Interestingly, the Gata-4 messenger RNA levels remained stable following Fbxw7 deletion. Fbxw7 silencing in SCs also induced progressive Leydig cell inefficiency and testosterone insufficiency. Collectively, these results demonstrate that Fbxw7 expression is required for SC maturation and function, potentially through degradation of GATA-4, to support pubertal testis development and spermatogenesis.

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Generation of Axin1 conditional mutant mice

genesis ◽

10.1002/dvg.20703 ◽

2011 ◽

Vol 49 (2) ◽

pp. 98-102 ◽

Cited By ~ 13

Author(s):

Rong Xie ◽

Rulang Jiang ◽

Di Chen

Keyword(s):

Mutant Mice ◽

Conditional Mutant

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Conditional deletion of the Bcl-x gene from erythroid cells results in hemolytic anemia and profound splenomegaly

Development ◽

10.1242/dev.127.22.4949 ◽

2000 ◽

Vol 127 (22) ◽

pp. 4949-4958 ◽

Cited By ~ 1

Author(s):

K.U. Wagner ◽

E. Claudio ◽

E.B. Rucker ◽

G. Riedlinger ◽

C. Broussard ◽

...

Keyword(s):

Hemolytic Anemia ◽

Cell Types ◽

Mutant Mice ◽

Erythroid Cells ◽

Bcl2 Family ◽

Conditional Deletion ◽

Recombination System ◽

Conditional Mutant ◽

X Gene ◽

Mmtv Ltr

Bcl-x is a member of the Bcl2 family and has been suggested to be important for the survival and maturation of various cell types including the erythroid lineage. To define the consequences of Bcl-x loss in erythroid cells and other adult tissues, we have generated mice conditionally deficient in the Bcl-x gene using the Cre-loxP recombination system. The temporal and spatial excision of the floxed Bcl-x locus was achieved by expressing the Cre recombinase gene under control of the MMTV-LTR. By the age of five weeks, Bcl-x conditional mutant mice exhibited hyperproliferation of megakaryocytes and a decline in the number of circulating platelets. Three-month-old animals suffered from severe hemolytic anemia, hyperplasia of immature erythroid cells and profound enlargement of the spleen. We demonstrate that Bcl-x is only required for the survival of erythroid cells at the end of maturation, which includes enucleated reticulocytes in circulation. The extensive proliferation of immature erythroid cells in the spleen and bone marrow might be the result of a fast turnover of late red blood cell precursors and accelerated erythropoiesis in response to tissue hypoxia. The increase in cell death of late erythroid cells is independent from the proapoptotic factor Bax, as demonstrated in conditional double mutant mice for Bcl-x and Bax. Mice conditionally deficient in Bcl-x permitted us for the first time to study the effects of Bcl-x deficiency on cell proliferation, maturation and survival under physiological conditions in an adult animal.

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ANIMAL MODELS: EC Boosts Funds for Mutant Mice

Science ◽

10.1126/science.292.5524.1985b ◽

2001 ◽

Vol 292 (5524) ◽

pp. 1985b-1987

Author(s):

M. Balter

Keyword(s):

Animal Models ◽

Mutant Mice

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Abstract 3937: Generation and Analysis of Neural Crest- and Endothelial-specific Mutant Mice for Foxc1

Circulation ◽

10.1161/circ.118.suppl_18.s_505-c ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Seungwoon Seo ◽

Hisaki Hayashi ◽

Tsutomu Kume

Keyword(s):

Neural Crest ◽

Corneal Stroma ◽

Cell Types ◽

Mutant Mice ◽

Specific Cell ◽

Cardiovascular Development ◽

Forkhead Transcription Factor ◽

Vascular Abnormalities ◽

Autonomous Function ◽

Conditional Mutant

The forkhead transcription factor Foxc1 has been implicated in craniofacial, ocular and cardiovascular development. Foxc1 is expressed in mesoderm- and neural crest (NC)-derived cells, including endothelial cells (ECs) of the heart and blood vessels and vascular smooth muscle cells. However, the precise role of Foxc1 in specific cell types still remains unclear. Therefore, to define the distinct function of Foxc1 in NC and EC, we have generated conditional mutant mice for Foxc1 crossed with either Tie2-Cre or Wnt1-Cre mice. EC-specific Foxc1 mutants survive until adulthood with no apparent embryonic defects, although they show vascular abnormalities in the adult. By contrast, NC-specific Foxc1 mutants die perinately with haemorrhagic hydrocephalus, rudimentary frontal bones, and abnormal patterning of the aortic arch. NC-derived cells also give rise to the stroma and endothelium of the cornea, an avascular organ whose transparency is critical for vision. Importantly, we found that NC-specific Foxc1 mutants show failure of the formation of the anterior chamber and corneal endothelium in the eye. Mutant corneal stroma is much thicker than normal with increased cell proliferation. Most Intriguingly, NC-specific Foxc1 mutants exhibit ectopic neovascularization in the cornea with significant upregulation of Mmp9, sFlt1, Flt1 and Tek at E15.5, while Vegfa and Fgf expression is not changed. By contrast, the cornea of EC-specific Foxc1 mutants is normally formed and avascular. These data suggest that the cell-autonomous function of Foxc1 in the neural crest is essential for craniofacial and cardiovascular development and that Foxc1 plays an important role in inhibition of vascular formation in the cornea.

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c-Met is essential for wound healing in the skin

The Journal of Cell Biology ◽

10.1083/jcb.200701086 ◽

2007 ◽

Vol 177 (1) ◽

pp. 151-162 ◽

Cited By ~ 198

Author(s):

Jolanta Chmielowiec ◽

Malgorzata Borowiak ◽

Markus Morkel ◽

Theresia Stradal ◽

Barbara Munz ◽

...

Keyword(s):

Wound Healing ◽

Wound Closure ◽

Regenerative Process ◽

Mutant Mice ◽

Skin Wounds ◽

Cell Growth And Migration ◽

Conditional Mutant ◽

Scratch Wound ◽

And Migration ◽

Hepatocyte Growth

Wound healing of the skin is a crucial regenerative process in adult mammals. We examined wound healing in conditional mutant mice, in which the c-Met gene that encodes the receptor of hepatocyte growth factor/scatter factor was mutated in the epidermis by cre recombinase. c-Met–deficient keratinocytes were unable to contribute to the reepithelialization of skin wounds. In conditional c-Met mutant mice, wound closure was slightly attenuated, but occurred exclusively by a few (5%) keratinocytes that had escaped recombination. This demonstrates that the wound process selected and amplified residual cells that express a functional c-Met receptor. We also cultured primary keratinocytes from the skin of conditional c-Met mutant mice and examined them in scratch wound assays. Again, closure of scratch wounds occurred by the few remaining c-Met–positive cells. Our data show that c-Met signaling not only controls cell growth and migration during embryogenesis but is also essential for the generation of the hyperproliferative epithelium in skin wounds, and thus for a fundamental regenerative process in the adult.

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