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Törnqvist, Gunilla
Publications (2 of 2) Show all publications
Jones, I., Hägglund, A.-C., Törnqvist, G., Nord, C., Ahlgren, U. & Carlsson, L. (2015). A novel mouse model of tuberous sclerosis complex (TSC): eye-specific Tsc1-ablation disrupts visual-pathway development. Disease Models and Mechanisms, 8(12), 1517-1529
Open this publication in new window or tab >>A novel mouse model of tuberous sclerosis complex (TSC): eye-specific Tsc1-ablation disrupts visual-pathway development
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2015 (English)In: Disease Models and Mechanisms, ISSN 1754-8403, E-ISSN 1754-8411, Vol. 8, no 12, p. 1517-1529Article in journal (Refereed) Published
Abstract [en]

Tuberous sclerosis complex (TSC) is an autosomal dominant syndrome that is best characterised by neurodevelopmental deficits and the presence of benign tumours (called hamartomas) in affected organs. This multi-organ disorder results from inactivating point mutations in either the TSC1 or the TSC2 genes and consequent activation of the canonical mammalian target of rapamycin complex 1 signalling (mTORC1) pathway. Because lesions to the eye are central to TSC diagnosis, we report here the generation and characterisation of the first eye-specific TSC mouse model. We demonstrate that conditional ablation of Tsc1 in eye-committed progenitor cells leads to the accelerated differentiation and subsequent ectopic radial migration of retinal ganglion cells. This results in an increase in retinal ganglion cell apoptosis and consequent regionalised axonal loss within the optic nerve and topographical changes to the contra- and ipsilateral input within the dorsal lateral geniculate nucleus. Eyes from adult mice exhibit aberrant retinal architecture and display all the classic neuropathological hallmarks of TSC, including an increase in organ and cell size, ring heterotopias, hamartomas with retinal detachment, and lamination defects. Our results provide the first major insight into the molecular etiology of TSC within the developing eye and demonstrate a pivotal role for Tsc1 in regulating various aspects of visual-pathway development. Our novel mouse model therefore provides a valuable resource for future studies concerning the molecular mechanisms underlying TSC and also as a platform to evaluate new therapeutic approaches for the treatment of this multi-organ disorder.

National Category
Other Basic Medicine
Identifiers
urn:nbn:se:umu:diva-120197 (URN)10.1242/dmm.021972 (DOI)000368905300004 ()26449264 (PubMedID)
Available from: 2016-05-11 Created: 2016-05-11 Last updated: 2018-06-07Bibliographically approved
Törnqvist, G. (2010). The role of Lhx2 in hair follicle morphogenesis and regeneration. (Licentiate dissertation). Umeå: Umeå Centre for Molecular Medicine, Umeå University
Open this publication in new window or tab >>The role of Lhx2 in hair follicle morphogenesis and regeneration
2010 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Hair is important for thermoregulation, physical protection, sensory activity, seasonal camouflage and social interactions. Hair is produced in hair follicles (HFs), complex mini-organs in the skin devoted to this task. HFs are formed during embryonic development (morphogenesis) and new hair is continuously generated throughout life since the postnatal HF goes through cycles of regression (catagen), quiescence (telogen) and growth (anagen). The transcriptional regulation of this process is not well understood. The LIM-homeodomain transcription factor Lhx2 has previously been shown to be critically involved in epithelial-mesenchymal interactions during development of various organs and a potent regulator of stem cell function. We therefore elucidated the expression pattern and function of Lhx2 during hair formation.

Lhx2 is expressed during both morphogenesis and anagen in cells scattered in the outer root sheath and in a subpopulation of the matrix cells in the proximal part of the hair bulb. Matrix cells are proliferating progenitor cells that differentiate into the components of the HF including the hair shaft. Expression is turned off during telogen, however Lhx2 expression reappears in the secondary hair germ immediately prior to initiation of the anagen stage. In contrast to previously published results Lhx2 appears to be expressed by progenitor cells distinct from those in the stem cell niche in the bulge region. The developmental-, stage- and cell-specific expression pattern of Lhx2 suggests that Lhx2 is involved in the generation and regeneration of hair.

To test our hypothesis we used different genetically modified mouse strains. First we studied the effect of over-expression of Lhx2 in the HFs using a mouse model where transgenic Lhx2 expression could be induced in dorsal skin. Using this model we could show that Lhx2 expression is sufficient to induce anagen. To analyze the consequence of lack-of-function of Lhx2 we developed a mouse model where it is possible to conditionally inactivate Lhx2 and a mouse strain harbouring a hypomorphic allele of Lhx2. Mice where Lhx2 was conditionally inactivated in postnatal HFs were unable to regrow hair on a shaved area whereas all controls did regrow their hair. The mutant HFs initiated anagen but were unable to produce normal hair shafts. Thus Lhx2 is required for postnatal hair formation. We used the mouse strain carrying a hypomorphic allele of Lhx2 to study the role of Lhx2 during HF morphogenesis. Embryos homozygous for the hypomorphic allele form significantly less HFs compared to control embryos, and the HFs that do form in the mutant embryos appear to be developmentally arrested. These results suggest that Lhx2 is also important during HF morphogenesis. Thus, Lhx2 is an essential positive regulator of hair generation and regeneration.

Place, publisher, year, edition, pages
Umeå: Umeå Centre for Molecular Medicine, Umeå University, 2010. p. 49
National Category
Biochemistry and Molecular Biology
Research subject
Molecular Cellbiology
Identifiers
urn:nbn:se:umu:diva-36155 (URN)
Presentation
2010-09-17, Major Groove, By 6L, Umeå University, Umeå, 09:00 (English)
Supervisors
Available from: 2010-09-27 Created: 2010-09-20 Last updated: 2018-06-08Bibliographically approved
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