scholarly journals Distinct roles for prominin-1 and photoreceptor cadherin in outer segment disc morphogenesis in CRISPR-altered X. laevis

2020 ◽  
pp. jcs.253906
Author(s):  
Brittany J. Carr ◽  
Paloma Stanar ◽  
Orson L. Moritz
Keyword(s):  
Plasma Membrane ◽  
Outer Segment ◽  
Structure And Function ◽  
Fusion Event ◽  
Disc Membrane ◽  
Structural Support ◽  
Horizontal Orientation ◽  
Degenerative Disorders ◽  
And Function ◽  
Null Mutants

Mutations in prominin-1 (prom1) and photoreceptor cadherin (cdhr1) are associated with inherited retinal degenerative disorders but their functions remain unknown. We used CRISPR-Cas9 to generate prom1-, cdhr1-, and prom1+cdhr1-null X. laevis and then documented the effects of these mutations on photoreceptor structure and function. Prom1-null mutations resulted in severely dysmorphic photoreceptors comprised of overgrown and disorganized disc membranes. Cone outer segments were more severely affected than rods and had an impaired ERG response. Cdhr1-null photoreceptors did not appear grossly dysmorphic, but ultrastructural analysis revealed that some disc membranes were overgrown or oriented vertically within the plasma membrane. Double-null mutants did not differ significantly from prom1-null mutants. Our results indicate that neither prom1 nor cdhr1 are necessary for outer segment disc membrane evagination or the fusion event that controls disc sealing. Rather, they are necessary for the higher-order organization of the outer segment. Prom1 may align and reinforce interactions between nascent disc leading edges, a function more critical in cones for structural support. Cdhr1 may secure discs in a horizontal orientation prior to fusion and regulate cone lamellae size.

scholarly journals Genetically-modified X. laevis indicate distinct roles for prominin-1 and photoreceptor cadherin in outer segment morphogenesis and retinal dystrophy

2020 ◽  
Author(s):  
Brittany J Carr ◽  
Paloma Stanar ◽  
Orson L Moritz
Keyword(s):  
Outer Segment ◽  
Retinal Dystrophy ◽  
Macular Dystrophy ◽  
Direct Effects ◽  
Fusion Event ◽  
Photoreceptor Outer Segment ◽  
Structural Support ◽  
Degenerative Disorders ◽  
And Function ◽  
Null Mutants

ABSTRACTMutations in prominin-1 (prom1) and photoreceptor cadherin (cdhr1) are associated with inherited retinal degenerative disorders such as retinitis pigmentosa, cone-rod dystrophy, and juvenile macular dystrophy. The proteins encoded by these genes are hypothesized to regulate photoreceptor outer segment disc morphogenesis, but their functions remain unknown. We used CRISPR/Cas9 to generate prom1-, cdhr1-, and prom1 + cdhr1-null X. laevis and then documented the effects of these mutations on photoreceptor structure and function. Prom1-null mutations resulted in dysmorphic photoreceptors comprised of overgrown and disorganized disc membranes. Cones were more severely affected than rods; outer segments were elongated and fragmented, and ERG response was impaired. Autofluorescent deposits in the outer segment layer of aging prom1-null animals indicate that secondary toxic effects to the retina or RPE drive retinal degeneration for this mutation, instead of direct effects on outer segment disc morphogenesis. Cdhr1-null photoreceptors did not appear grossly dysmorphic, but ultrastructural analysis revealed that some disc membranes were overgrown or aligned vertically within the plasma membrane. Prom1 + cdhr1-null mutants did not differ significantly from prom1-null mutants. Our results indicate that neither prom1 nor cdhr1 are necessary for outer segment disc membrane evagination or the membrane fusion event involved in disc sealing. Rather, they are necessary for higher-order organization of the nascent outer segment discs. Prom1 may align and reinforce interactions between the disc leading edges, a function more critical in cone photoreceptors for structural support. Cdhr1 may help to align nascent discs and maintain horizontal disc orientation prior to fusion.

Cellular structure and function

2021 ◽  
pp. 1-104
Keyword(s):  
Plasma Membrane ◽  
Nucleic Acids ◽  
Cellular Structure ◽  
Structure And Function ◽  
The Body ◽  
Signalling Pathways ◽  
Cellular Functions ◽  
Pharmacological Agents ◽  
Intracellular Organelles ◽  
And Function

‘Cellular structure and function’ covers the roles, structures, and functions of the main four types of macromolecules of the human body, namely proteins, lipids, carbohydrates, and nucleic acids. For these macromolecules, the roles and types of each class are discussed (for proteins this includes their roles as structural proteins and enzymes and their kinetics; for lipids, the roles and types of lipid found in the body are considered; for carbohydrates, their roles including structural and metabolic are discussed; and the structure of nucleic acids is described). Then follows a description of the organization of the cell, including the plasma membrane and its components, and the intracellular organelles. Cell growth, division, and apoptosis are covered, as are the formation of gametes, and finally the principles of how cellular functions can be modulated by pharmacological agents through receptors and signalling pathways are discussed.

scholarly journals ENaC structure and function in the wake of a resolved structure of a family member

2011 ◽  
Vol 301 (4) ◽  
pp. F684-F696 ◽  
Author(s):  
Ossama B. Kashlan ◽  
Thomas R. Kleyman
Keyword(s):  
Plasma Membrane ◽  
Ion Channel ◽  
Functional Data ◽  
Ion Selectivity ◽  
External Environment ◽  
Structure And Function ◽  
Close Proximity ◽  
Channel Assembly ◽  
And Function ◽  
Insight Into

Our understanding of epithelial Na+ channel (ENaC) structure and function has been profoundly impacted by the resolved structure of the homologous acid-sensing ion channel 1 (ASIC1). The structure of the extracellular and pore regions provide insight into channel assembly, processing, and the ability of these channels to sense the external environment. The absence of intracellular structures precludes insight into important interactions with intracellular factors that regulate trafficking and function. The primary sequences of ASIC1 and ENaC subunits are well conserved within the regions that are within or in close proximity to the plasma membrane, but poorly conserved in peripheral domains that may functionally differentiate family members. This review examines functional data, including ion selectivity, gating, and amiloride block, in light of the resolved ASIC1 structure.

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