Browsing by Author "Harikrishnan, Hemavathy"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Rhodopsin Mislocalization Drives Ciliary Dysregulation in a Novel Autosomal Dominant Retinitis Pigmentosa Knock-In Mouse Model
    (Wiley, 2024) Takita, Shimpei; Jahan, Sultana; Imanishi, Sanae; Harikrishnan, Hemavathy; LePage, David; Mann, Rachel J.; Conlon, Ronald A.; Miyagi, Masaru; Imanishi, Yoshikazu; Ophthalmology, School of Medicine
    Rhodopsin mislocalization encompasses various blind conditions. Rhodopsin mislocalization is the primary factor leading to rod photoreceptor dysfunction and degeneration in autosomal dominant retinitis pigmentosa (adRP) caused by class I mutations. In this study, we report a new knock-in mouse model that harbors a class I Q344X mutation in the endogenous rhodopsin gene, which causes rod photoreceptor degeneration in an autosomal dominant pattern. In RhoQ344X/+ mice, mRNA transcripts from the wild-type (Rho) and RhoQ344X mutant rhodopsin alleles are expressed at equal levels. However, the amount of RHOQ344X mutant protein is 2.7 times lower than that of wild-type rhodopsin, a finding consistent with the rapid degradation of the mutant protein. Immunofluorescence microscopy indicates that RHOQ344X is mislocalized to the inner segment and outer nuclear layers of rod photoreceptors in both RhoQ344X/+ and RhoQ344X/Q344X mice, confirming the essential role of the C-terminal VxPx motif in promoting OS delivery of rhodopsin. The mislocalization of RHOQ344X is associated with the concurrent mislocalization of wild-type rhodopsin in RhoQ344X/+ mice. To understand the global changes in proteostasis, we conducted quantitative proteomics analysis and found attenuated expression of rod-specific OS membrane proteins accompanying reduced expression of ciliopathy causative gene products, including constituents of BBSome and axonemal dynein subunit. Those studies unveil a novel negative feedback regulation involving ciliopathy-associated proteins. In this process, a defect in the trafficking signal leads to a reduced quantity of the trafficking apparatus, culminating in a widespread reduction in the transport of ciliary proteins.
  • Thumbnail Image
    Item
    A smartphone based method for mouse fundus imaging
    (Elsevier, 2021) Peng, Michael; Park, Bomina; Harikrishnan, Hemavathy; Jahan, Sultana N.; Dai, Jiannong; Rayana, Naga Pradeep; Sugali, Chenna Kesavulu; Sharma, Tasneem P.; Imanishi, Sanae; Imanishi, Yoshikazu; Corson, Timothy W.; Mao, Weiming; Ophthalmology, School of Medicine
    Noninvasive in vivo imaging of the mouse retina is essential for eye research. However, imaging the mouse fundus is challenging due to its small size and requires specialized equipment, maintenance, and training. These issues hinder the routine evaluation of the mouse retina. In this study, we developed a noncontact imaging system consisting of a smartphone, a 90D condensing lens, a homemade light diaphragm, a tripod, and a Bluetooth remote. With minimal training, examiners were able to capture fundus images from the mouse retina. We also found that fundus images captured using our system from wild type mice, mice with laser-induced retinal injury, and a mouse model of retinitis pigmentosa showed a quality similar to those captured using a commercial fundus camera. These images enabled us to identify normal structures and pathological changes in the mouse retina. Additionally, fluorescein angiography was possible with the smartphone system. We believe that the smartphone imaging system is low cost, simple, accessible, easy to operate, and suitable for the routine screening and examination of the mouse eye.