Dopamine-induced interactions of female mouse hypothalamic proteins with progestin receptor-A in the absence of hormone

Neural progestin receptors (PR) function in reproduction, neural development, neuroprotection, learning, memory, and anxiety response. In the absence of progestins, PR can be activated by dopamine (DA) in the rodent hypothalamus to elicit female sexual behavior. This study investigated mechanisms of DA activation of PR by testing the hypothesis that proteins from DA-treated hypothalami interact with PR in the absence of progestins. Ovariectomized, estradiol-primed mice were infused with a D1-receptor agonist, SKF38393 (SKF), into the 3(rd) ventricle 30 minutes prior to euthanasia. Proteins from SKF-treated hypothalami were pulled-down with GST-tagged mouse PR-A or PR-B and the interactomes were analyzed by mass spectrometry. The largest functional group to interact with PR-A in a DA-dependent manner was synaptic proteins. To test the hypothesis that DA activation of PR regulates synaptic proteins, we developed estradiol-induced PR-expressing hypothalamic-like neurons derived from human-induced pluripotent stem cells (hiPSCs). Similar to progesterone (P4), SKF treatment of hiPSCs increased synapsin-1/2 expression. This SKF-dependent effect was blocked by the PR antagonist RU486, suggesting that PR are necessary for this DA-induced increase. The second largest DA-dependent PR-A protein interactome comprised of metabolic regulators involved in glucose metabolism, lipid synthesis, and mitochondrial energy production. Interestingly, hypothalamic proteins interacted with PR-A, but not PR-B, in an SKF-dependent manner, suggesting that DA promotes interaction of multiple hypothalamic proteins with PR-A. These in vivo and in vitro results indicate novel mechanisms by which DA can differentially activate PR isoforms in the absence of P4 and provide a better understanding of ligand-independent PR activation in reproductive, metabolic, and mental health disorders in women

Repair of the degenerate retina by photoreceptor transplantation

Despite different aetiologies, age-related macular degeneration and most inherited retinal disorders culminate in the same final common pathway, the loss of photoreceptors. There are few treatments and none reverse the loss of vision. Photoreceptor replacement by transplantation is proposed as a broad treatment strategy applicable to all degenerations. Recently, we demonstrated restoration of vision following rod-photoreceptor transplantation into a mouse model of stationary night-blindness, raising the critical question of whether photoreceptor replacement is equally effective in different types and stages of degeneration. We present a comprehensive assessment of rod-photoreceptor transplantation across six murine models of inherited photoreceptor degeneration. Transplantation is feasible in all models examined but disease type has a major impact on outcome, as assessed both by the morphology and number of integrated rod-photoreceptors. Integration can increase (Prph2(+/Δ307)), decrease (Crb1(rd8/rd8), Gnat1(-/-), Rho(-/-)), or remain constant (PDE6β(rd1/rd1), Prph2(rd2/rd2)) with disease progression, depending upon the gene defect, with no correlation with severity. Robust integration is possible even in late-stage disease. Glial scarring and outer limiting membrane integrity, features that change with degeneration, significantly affect transplanted photoreceptor integration. Combined breakdown of these barriers markedly increases integration in a model with an intact outer limiting membrane, strong gliotic response, and otherwise poor transplantation outcome (Rho(-/-)), leading to an eightfold increase in integration and restoration of visual function. Thus, it is possible to achieve robust integration across a broad range of inherited retinopathies. Moreover, transplantation outcome can be improved by administering appropriate, tailored manipulations of the recipient environment.</p