Elucidating the role of Ankyrin-R in the nervous system

PROJECT SUMMARY. Ankyrin proteins, ankyrin-­R (ANK1), ankyrin-­B (ANK2), and ankyrin-­G (ANK3), referred to as AnkR, AnkB, and AnkG respectively, are found throughout the body and act as the primary link between the spectrin-­ based cytoskeleton and the cytoplasmic domain of many membrane-­associated proteins through their conserved 24 ANK repeats. Although AnkG and AnkB are well recognized as important domain organizers within the nervous system, few studies have investigated AnkR’s role. Instead, research into the function of AnkR has predominately focused on its function in erythrocytes where it creates structural stability by anchoring Band 3 to ßI spectrin2, with mutations in AnkR resulting in severe spherocytic anemia. Interestingly though, our lab recently showed AnkR can compensate for a loss of AnkG and cluster Na+ channels at nodes of Ranvier, suggesting a neurological role. Additionally, multiple studies have indicated various neurological disturbances have disruptions in AnkR, including cerebellar dysfunction and Alzheimer’s disease. Yet still, the expression profile, consequences of disruption, and interacting proteins of AnkR in the nervous system remain poorly understood. I hypothesize that the ankyrin family of proteins play complementary, but distinct roles in the brain where they tether transmembrane proteins to the spectrin cytoskeleton. The objectives proposed are: to elucidate AnkR’s expression patterns, functions, and molecular interactions in the brain. Aim 1 will determine the temporal and spatial expression of AnkR in the brain. By analysis of AnkR through postnatal development I will establish the temporal, spatial, and cell-­type specific expression. Aim 2 will determine the cellular and behavioral consequences of disruption of AnkR through analysis of a new AnkR conditional knockout mouse model, which allows neuronal populations of cells to be studied, while sparing erythroctes. Examination of phenotypes will yield key insights into AnkR function in the nervous system. Aim 3 will determine the cytoskeletal and membrane proteins AnkR interacts with in the nervous system. This will reveal the normal protein function as well as mechanistic insight into the phenotypes resulting from loss. Completion of these studies will reveal the function of AnkR in the brain, and enhance our understanding of the molecular mechanisms governing regional protein organization in the developing, aging, and diseased brain. By comparing what I learn about about AnkR to AnkG and AnkB, I will resolve the hypothesis to conclude if AnkR functions redundantly, or has a unique neuronal function. Moreover, data gained from these experiments may also explain AnkR’s role in neurological conditions such as Alzheimer’s disease (AD), schizophrenia, and cerebellar dysfunction in which deregulation of AnkR has been proposed. In total, completion of the proposed experiments will determine the role of AnkR in normal brain function.

PROJECT SUMMARY.   Ankyrin proteins, ankyrin-­R (ANK1), ankyrin-­B (ANK2), and ankyrin-­G (ANK3), referred to as AnkR,  AnkB, and AnkG respectively, are found throughout the body and act as the primary link between the spectrin-­ based cytoskeleton and the cytoplasmic domain of many membrane-­associated proteins through their  conserved 24 ANK repeats. Although AnkG and AnkB are well recognized as important domain organizers  within the nervous system, few studies have investigated AnkR’s role. Instead, research into the function of  AnkR has predominately focused on its function in erythrocytes where it creates structural stability by  anchoring Band 3 to ßI spectrin2, with mutations in AnkR resulting in severe spherocytic anemia. Interestingly  though, our lab recently showed AnkR can compensate for a loss of AnkG and cluster Na+ channels at nodes  of Ranvier, suggesting a neurological role. Additionally, multiple studies have indicated various neurological  disturbances have disruptions in AnkR, including cerebellar dysfunction and Alzheimer’s  disease. Yet still, the expression profile, consequences of disruption, and interacting proteins of  AnkR in the nervous system remain poorly understood. I hypothesize that the ankyrin family of proteins play  complementary, but distinct roles in the brain where they tether transmembrane proteins to the spectrin  cytoskeleton. The objectives proposed are: to elucidate AnkR’s expression patterns, functions, and molecular  interactions in the brain. Aim 1 will determine the temporal and spatial expression of AnkR in the brain. By  analysis of AnkR through postnatal development I will establish the temporal, spatial, and cell-­type specific  expression. Aim 2 will determine the cellular and behavioral consequences of disruption of AnkR through  analysis of a new AnkR conditional knockout mouse model, which allows neuronal populations of cells to be  studied, while sparing erythroctes. Examination of phenotypes will yield key insights into AnkR function in the  nervous system. Aim 3 will determine the cytoskeletal and membrane proteins AnkR interacts with in the  nervous system. This will reveal the normal protein function as well as mechanistic insight into the phenotypes  resulting from loss. Completion of these studies will reveal the function of AnkR in the brain, and enhance our  understanding of the molecular mechanisms governing regional protein organization in the developing, aging,  and diseased brain. By comparing what I learn about about AnkR to AnkG and AnkB, I will resolve the  hypothesis to conclude if AnkR functions redundantly, or has a unique neuronal function. Moreover, data  gained from these experiments may also explain AnkR’s role in neurological conditions such as Alzheimer’s  disease (AD), schizophrenia, and cerebellar dysfunction in which deregulation of AnkR has been proposed. In  total, completion of the proposed experiments will determine the role of AnkR in normal brain function.