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Loss of SPATA7 function causes the pathogenesis of Leber congenital amaurosis and retinitis pigmentosa. Spata7 knockout mice mimic human SPATA7-related retinal disease with apparent photoreceptor degeneration observed as early as postnatal day 15 (P15). To test the efficacy of adeno-associated virus (AAV)-mediated gene therapy for rescue of photoreceptor survival and function in Spata7 mutant mice, we employed the AAV8(Y733F) vector carrying hGRK1-driven full-length FLAG-tagged Spata7 cDNA to target both rod and cone photoreceptors. Following subretinal injection of this vector, FLAG-tagged SPATA7 was found to colocalize with endogenous SPATA7 in wild-type mice. In Spata7 mutant mice initially treated at P15, we observed improvement of photoresponse, photoreceptor ultrastructure and significant alleviation of photoreceptor degeneration. Furthermore, we performed treatments at P28 and P56 and found that all treatments (P15-P56) can ameliorate rod and cone loss in the long term (1 year); however, none efficiently protect photoreceptors from degeneration by 86 weeks of age as only a small amount of treated photoreceptors can survive to this time. This study demonstrates long-term improvement of photoreceptor function by AAV8(Y733F)-introduced Spata7 expression in a mouse model as potential treatment of the human disease, but also suggests that treated mutant photoreceptors still undergo progressive degeneration. [ABSTRACT FROM AUTHOR]

Loss of epithelial integrity often correlates with the progression of malignant tumors. Sds22, a regulatory subunit of protein phosphatase 1 (PP1), has recently been linked to regulation of epithelial polarity in Drosophila. However, its role in tumorigenesis remains obscure. In this study, using Drosophila imaginal tissue as an in vivo model system, we show that sds22 is a new potential tumor suppressor gene in Drosophila. Without sds22, cells lose epithelial architecture, and become invasive and tumorigenic when combined with Ras overexpression; conversely, sds22 overexpression can largely suppress tumorigenic growth of RasV12scrib−/− mutant cells. Mechanistically, we show that sds22 prevents cell invasion and metastasis by inhibiting myosin II and Jun N-terminal kinase (JNK) activity downstream of PP1. Loss of this inhibition causes cells to lose epithelial organization and promotes cell invasion. Finally, human Sds22 is focally deleted and downregulated in multiple carcinomas, and this downregulation correlates with tumor progression, suggesting that sds22 inactivation may contribute to tumorigenesis and metastatic potential in human cancers via a similar mechanism. [ABSTRACT FROM AUTHOR]

The Drosophila genes eyeless, eyes absent, sine oculis, and dachshund cooperate as key regulators of retinal cell-fate determination. Homologues of eyeless ( Pax6), eyes absent ( Eya1-2), and sine oculis ( Six3) have been identified and are expressed in the developing vertebrate eye. We have cloned and characterized the structure and expression of mouse Dach, a homologue of Drosophila dachshund. Sequence analysis reveals the presence of two motifs, DD1 and DD2, which may be involved in the function of Dach/Dachshund as gene regulatory factors. In addition, DD1 shares sequence similarity to N-terminal sequences of Ski and SnoN, which are involved in cellular transformation and differentiation. Mouse and human Dach/DACH were localized to chromosome 14E1 and 13q21.3–22, respectively, by fluorescence in situ hybridization. Finally, in situ hybridization analysis demonstrated that Dach is expressed in similar tissues to those observed in Drosophila, including the embryonic nervous system, sensory organs, and limbs. The finding of Dach expression in the eye completes the list of vertebrate homologues of eyeless, eyes absent, sine oculis, and dachshund which as a group may function to control cell-fate determination in the vertebrate eye. [ABSTRACT FROM AUTHOR]