E RPE of the ChmFlox, Tyr-Cre+ mouse exhibited patchy depigmentation (Fig.

E RPE of the ChmFlox, Tyr-Cre+ mouse exhibited patchy depigmentation (Fig. 1B and Fig. S1B) overall there was not a significant reduction in melanosome number (Fig. 3C). However the percentage of these melanosomes that associated with lipofuscin granules more than doubled in 6-month old ChmFlox, Tyr-Cre+ and 2-year old wild type mice compared with 6-month old control mice (Fig. 3E), indicating that association of melanosomes with lipofuscin granules is a feature of aging in the RPE and is accelerated by the loss of Rep1.*percentage of the length of RPE analysed. doi:10.1371/journal.pone.0057769.ta small amount of Rab27a is prenylated preventing a total block in melanosome movement. Similarly, melanosome movement in skin melanocytes is only partially affected in ChmFlox, 23977191 Tyr-Cre+, as reflected by the mild coat colour defect [9]. No clear changes were observed in melanosome distribution in uveal melanocytes (as shown in Fig. S1). In addition no obvious changes in the number of melanosomes and/or melanocytes in the choroid of ChmFlox, Tyr-Cre+ were observed. In both ChmFlox, Tyr-Cre+ and littermate control mice choroidal melanosomes vary in size (Fig. S1C and S1D). Their distribution was not obviously affected by loss of REP1 but uveal melanocytes are extremely packed with melanosomes, making changes in their distribution difficult to analyse. It is worth noting that in the ashen mouse, that exhibits dramatic changes in melanosome distribution in the RPE [6,7], no clear changes in uveal melanocytes can be observed. Delayed phagosome degradation has been demonstrated in vitro following acute depletion of REP1 [10]. To determine whether phagosome degradation was impaired in vivo following deletion of Rep1 in the RPE the number of phagosomes in the RPE was quantified using rhodopsin immunofluorescence of retinal sections (Fig. 2B). Phase images allowed the pigmented RPE to be readily identified in the tissue so that rhodopsin-positive phagosomes could be distinguished from the rest of the rhodopsin staining in the photoreceptor outer segment (POS) (Fig. 2A). The number of phagosomes 30 minutes after light onset was not significantlyLoss of Rep1 in the RPE causes Accumulation of Extracellular DepositsFurther analysis by TEM of the morphology of the RPE of 5month old ChmFlox, Tyr-Cre+ eyes revealed disorganisation of the basal infoldings (BIs) such that they were absent in some areas and extended far into the cytoplasm of the RPE cells in other areas (Fig. 4B and 4C). In contrast, the thickness and organisation of the BIs was regular throughout the eyecup of age-matched wild type or littermate ChmFlox eyes (Fig. 4A). Additionally, fibrillar materials were observed between the basal membrane of the RPE and the basal lamina [Basal laminar Deposits (BlamDs)] more frequently in ChmFlox, Tyr-Cre+ mice than in ChmFlox order 166518-60-1 controls (Fig. 4C). Late BLamDs had more defined striations, resembling banded HIV-RT inhibitor 1 collagen type VI [13], observed in the eyes of AMD [14], Sorsby’s fundus dystrophy patients [15] and CHM carriers [16]. These deposits also contained membrane debris and vesicles. They were observed less frequently in 5-month old ChmFlox, Tyr-Cre+ mice but were common by 1-year (Fig. 4D ). The deposits were measured along a length of RPE and results in Figure 5 and Table 1 show the percentage of RPE containing deposits within the length of RPE analysed. BlamDs are variable in both ChmFlox, Tyr-Cre+ and control mice, both in terms of frequency and extent. Cont.E RPE of the ChmFlox, Tyr-Cre+ mouse exhibited patchy depigmentation (Fig. 1B and Fig. S1B) overall there was not a significant reduction in melanosome number (Fig. 3C). However the percentage of these melanosomes that associated with lipofuscin granules more than doubled in 6-month old ChmFlox, Tyr-Cre+ and 2-year old wild type mice compared with 6-month old control mice (Fig. 3E), indicating that association of melanosomes with lipofuscin granules is a feature of aging in the RPE and is accelerated by the loss of Rep1.*percentage of the length of RPE analysed. doi:10.1371/journal.pone.0057769.ta small amount of Rab27a is prenylated preventing a total block in melanosome movement. Similarly, melanosome movement in skin melanocytes is only partially affected in ChmFlox, 23977191 Tyr-Cre+, as reflected by the mild coat colour defect [9]. No clear changes were observed in melanosome distribution in uveal melanocytes (as shown in Fig. S1). In addition no obvious changes in the number of melanosomes and/or melanocytes in the choroid of ChmFlox, Tyr-Cre+ were observed. In both ChmFlox, Tyr-Cre+ and littermate control mice choroidal melanosomes vary in size (Fig. S1C and S1D). Their distribution was not obviously affected by loss of REP1 but uveal melanocytes are extremely packed with melanosomes, making changes in their distribution difficult to analyse. It is worth noting that in the ashen mouse, that exhibits dramatic changes in melanosome distribution in the RPE [6,7], no clear changes in uveal melanocytes can be observed. Delayed phagosome degradation has been demonstrated in vitro following acute depletion of REP1 [10]. To determine whether phagosome degradation was impaired in vivo following deletion of Rep1 in the RPE the number of phagosomes in the RPE was quantified using rhodopsin immunofluorescence of retinal sections (Fig. 2B). Phase images allowed the pigmented RPE to be readily identified in the tissue so that rhodopsin-positive phagosomes could be distinguished from the rest of the rhodopsin staining in the photoreceptor outer segment (POS) (Fig. 2A). The number of phagosomes 30 minutes after light onset was not significantlyLoss of Rep1 in the RPE causes Accumulation of Extracellular DepositsFurther analysis by TEM of the morphology of the RPE of 5month old ChmFlox, Tyr-Cre+ eyes revealed disorganisation of the basal infoldings (BIs) such that they were absent in some areas and extended far into the cytoplasm of the RPE cells in other areas (Fig. 4B and 4C). In contrast, the thickness and organisation of the BIs was regular throughout the eyecup of age-matched wild type or littermate ChmFlox eyes (Fig. 4A). Additionally, fibrillar materials were observed between the basal membrane of the RPE and the basal lamina [Basal laminar Deposits (BlamDs)] more frequently in ChmFlox, Tyr-Cre+ mice than in ChmFlox controls (Fig. 4C). Late BLamDs had more defined striations, resembling banded collagen type VI [13], observed in the eyes of AMD [14], Sorsby’s fundus dystrophy patients [15] and CHM carriers [16]. These deposits also contained membrane debris and vesicles. They were observed less frequently in 5-month old ChmFlox, Tyr-Cre+ mice but were common by 1-year (Fig. 4D ). The deposits were measured along a length of RPE and results in Figure 5 and Table 1 show the percentage of RPE containing deposits within the length of RPE analysed. BlamDs are variable in both ChmFlox, Tyr-Cre+ and control mice, both in terms of frequency and extent. Cont.