Faculty Collaboration Database

Targeted disruption of Tbc1d20 with zinc-finger nucleases causes cataracts and testicular abnormalities in mice. BMC Genet 2014 Dec 05;15:135

Date

12/06/2014

Pubmed ID

25476608

Pubmed Central ID

PMC4266191

DOI

10.1186/s12863-014-0135-2

Scopus ID

2-s2.0-84964313193 (requires institutional sign-in at Scopus site)   17 Citations

Abstract

BACKGROUND: Loss-of-function mutations in TBC1D20 cause Warburg Micro syndrome 4 (WARBM4), which is an autosomal recessive syndromic disorder characterized by eye, brain, and genital abnormalities. Blind sterile (bs) mice carry a Tbc1d20-null mutation and exhibit cataracts and testicular phenotypes similar to those observed in WARBM4 patients. In addition to TBC1D20, mutations in RAB3GAP1, RAB3GAP2 and RAB18 cause WARBM1-3 respectively. However, regardless of which gene harbors the causative mutation, all individuals affected with WARBM exhibit indistinguishable clinical presentations. In contrast, bs, Rab3gap1 (-/-) , and Rab18 (-/-) mice exhibit distinct phenotypes; this phenotypic variability of WARBM mice was previously attributed to potential compensatory mechanisms. Rab3gap1 (-/-) and Rab18 (-/-) mice were genetically engineered using standard approaches, whereas the Tbc1d20 mutation in the bs mice arose spontaneously. There is the possibility that another unidentified mutation within the bs linkage disequilibrium may be contributing to the bs phenotypes and thus contributing to the phenotypic variability in WARBM mice. The goal of this study was to establish the phenotypic consequences in mice caused by the disruption of the Tbc1d20 gene.

RESULTS: The zinc finger nuclease (ZFN) mediated genomic editing generated a Tbc1d20 c.[418_426del] deletion encoding a putative TBC1D20-ZFN protein with an in-frame p.[H140_Y143del] deletion within the highly conserved TBC domain. The evaluation of Tbc1d20 (ZFN/ZFN) eyes identified severe cataracts and thickened pupillary sphincter muscle. Tbc1d20 (ZFN/ZFN) males are infertile and the analysis of the seminiferous tubules identified disrupted acrosomal development. The compound heterozygote Tbc1d20 (ZFN/bs) mice, generated from an allelic bs/+ X Tbc1d20 (ZFN/+) cross, exhibited cataracts and aberrant acrosomal development indicating a failure to complement.

CONCLUSIONS: Our findings show that the disruption of Tbc1d20 in mice results in cataracts and aberrant acrosomal formation, thus establishing bs and Tbc1d20 (ZFN/ZFN) as allelic variants. Although the WARBM molecular disease etiology remains unclear, both the bs and Tbc1d20 (ZFN/ZFN) mice are excellent model organisms for future studies to establish TBC1D20-mediated molecular and cellular functions.

Author List

Park AK, Liegel RP, Ronchetti A, Ebert AD, Geurts A, Sidjanin DJ

Authors

Allison D. Ebert PhD Associate Professor in the Cell Biology, Neurobiology and Anatomy department at Medical College of Wisconsin
Aron Geurts PhD Professor in the Physiology department at Medical College of Wisconsin
Danielle Sidjanin Maier PhD Nurse Practitioner in the Medicine department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Acrosome
Animals
Base Sequence
Cataract
Endodeoxyribonucleases
Female
Gene Expression
Gene Knockdown Techniques
Genetic Association Studies
Genetic Engineering
HeLa Cells
Humans
Male
Mice, Inbred C57BL
Mice, Inbred DBA
Mice, Transgenic
Sequence Analysis, DNA
Testis
Zinc Fingers
rab1 GTP-Binding Proteins