Tamoxifen-Containing Eye Drops Successfully Trigger Cre-Mediated Recombination in the Entire Eye

Schlecht, Anja; Leimbeck, Sarah V.; Tamm, Ernst R.; Braunger, Barbara M.

doi:10.1007/978-3-319-17121-0_66

Cited by 10 publications

(16 citation statements)

References 11 publications

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“…To start localized drug treatment before onset of microglia activation we administered tamoxifen (tmx) as eye drops starting at P10. Schlecht et al previously demonstrated that tmx eye drops applied to closed eyelids of mice from P8 through P12 are sufficient to yield efficient Cre induction in the posterior retina implying that tmx reaches the posterior eye if applied to closed eyelids ( 35 ). Here, RCS rats received eye drops of 10 μl of 5 mg/ml tmx in corn oil into both eyes 3 times a day.…”

Section: Methodsmentioning

confidence: 99%

“…In experimental animals, tmx is commonly used to control gene expression via engineered tmx-inducible promoters (43). Systemic application, via intraperitoneal injection or oral supplementation, and topical administration via creams and eye drops have been successfully used in published studies (35,43,44). Schlecht and colleagues showed that tmx administration as eye drops from P8 through P12 yields effects on outer retinal cells indicating that topical tmx penetrates eye tissues reaching effective concentration even in the posterior retina (35).…”

Section: Suppression Of Microglia By Tamoxifen Eye Drops Mitigates Phmentioning

confidence: 99%

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Microglia Inhibition Delays Retinal Degeneration Due to MerTK Phagocytosis Receptor Deficiency

2020

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Retinitis Pigmentosa (RP) is a group of inherited retinal diseases characterized by progressive loss of rod followed by cone photoreceptors. An especially early onset form of RP with blindness in teenage years is caused by mutations in mertk, the gene encoding the clearance phagocytosis receptor Mer tyrosine kinase (MerTK). The cause for blindness in mutant MerTK-associated RP (mutMerTK-RP) is the failure of retinal pigment epithelial cells in diurnal phagocytosis of spent photoreceptor outer segment debris. However, the early onset and very fast progression of degeneration in mutMerTK-RP remains unexplained. Here, we explored the role of microglia in the Royal College of Surgeons (RCS) rat model of mutMerTK-RP. We found elevated levels of inflammatory cytokines and CD68 microglia activation marker, and more ionized calcium-binding adapter molecule 1 (Iba-1) positive microglia in RCS retina when compared to wild-type retina as early as postnatal day 14 (P14). Strikingly, renewal of photoreceptor outer segments in P14 wild-type rat retina is still immature with low levels of RPE phagocytosis implying that at this early age lack of this process in RCS rats is unlikely to distress photoreceptors. Although the total number of Iba-1 positive retinal microglia remains constant from P14 to P30, we observed increasing numbers of microglia in the outer retina from P20 implying migration to the outer retina before onset of photoreceptor cell death at ∼P25. Iba-1 and CD68 levels also increase in the retina during this time period suggesting microglia activation. To determine whether microglia affect the degenerative process, we suppressed retinal microglia in vivo using tamoxifen or a combination of tamoxifen and liposomal clodronate. Treatments partly prevented elevation of Iba-1 and CD68 and relocalization of microglia. Moreover, treatments led to partial but significant retention of photoreceptor viability and photoreceptor function. We conclude that loss of the phagocytosis receptor MerTK causes microglia activation and relocalization in the retina before lack of RPE phagocytosis causes overt retinal degeneration, and that microglia activities accelerate loss of photoreceptors in mutMerTK-RP. These results suggest that therapies targeting microglia may delay onset and slow the progression of this blinding disease.

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Section: Methodsmentioning

confidence: 99%

Section: Suppression Of Microglia By Tamoxifen Eye Drops Mitigates Phmentioning

confidence: 99%

Microglia Inhibition Delays Retinal Degeneration Due to MerTK Phagocytosis Receptor Deficiency

2020

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“…in which recombination is induced by localized treatment with tamoxifen. 53,54 If it were bred into the G305X Cacna1f-KO background, this inducible system would allow one to establish the developmental window during which transgenic α 1F expression can rescue normal retinal structure and function.…”

Section: Discussionmentioning

confidence: 99%

Transgenic Expression of Cacna1f Rescues Vision and Retinal Morphology in a Mouse Model of Congenital Stationary Night Blindness 2A (CSNB2A)

Waldner

Ito

Chen

et al. 2020

Trans. Vis. Sci. Tech.

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“…After genotyping, one group of animals was treated with standard intraperitoneal (ip) injections of 100 ul 20 mg/ml tamoxifen in corn oil daily for five consecutive days (Jackson Laboratories protocol). The other group was treated by 5 ul 5 mg/ml tamoxifen in corn oil three times a day for five consecutive days [15]. As controls, Cre and TdTomatopositive mice were treated with corn oil either via ip or via eye drops.…”

Section: Animals All Animal Procedures Were Performed In Accordance mentioning

confidence: 99%

Retina-specific targeting of pericytes reveals structural diversity and enables control of capillary blood flow

Ivanova

Corona

Eleftheriou

et al. 2020

Preprint

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Pericytes are a unique class of mural cells essential for angiogenesis, maintenance of the vasculature and are key players in microvascular pathology. However, their diversity and specific roles are poorly understood, limiting our insight into vascular physiology and the ability to develop effective therapies. Here, in the mouse retina, a tractable model of the CNS, we evaluated distinct classes of mural cells along the vascular tree for both structural characterization and physiological manipulation of blood flow. To accomplish this, we first tested three inducible mural cell-specific mouse lines using a sensitive Ai14 reporter and tamoxifen application either by a systemic injection, or by local administration in the form of eye drops. Across three lines, under either the PDGFRb or NG2 promoter, the specificity and pattern of Cre activation varied significantly. In particular, a mouse line with Cre under the NG2 promoter resulted in sparse TdTomato labeling of mural cells, allowing for an unambiguous characterization of anatomical features of individual sphincter cells and capillary pericytes.Furthermore, in one PDGFRb line, we found that focal eye drop application of tamoxifen led to an exclusive Cre-activation in pericytes, without affecting arterial mural cells. We then used this approach to boost capillary blood flow by selective expression of Halorhodopsin, a highly precise hyperpolarizing optogenetic actuator. The ability to exclusively target capillary pericytes may prove a precise and potentially powerful tool to treat microcirculation deficit, a common pathology in numerous diseases. *

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Tamoxifen-Containing Eye Drops Successfully Trigger Cre-Mediated Recombination in the Entire Eye

Cited by 10 publications

References 11 publications

Microglia Inhibition Delays Retinal Degeneration Due to MerTK Phagocytosis Receptor Deficiency

Microglia Inhibition Delays Retinal Degeneration Due to MerTK Phagocytosis Receptor Deficiency

Transgenic Expression of Cacna1f Rescues Vision and Retinal Morphology in a Mouse Model of Congenital Stationary Night Blindness 2A (CSNB2A)

Retina-specific targeting of pericytes reveals structural diversity and enables control of capillary blood flow

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