Associations of actigraphy measures of sleep duration and continuity with executive function, vigilance, and fine motor control in children with snoring and mild sleep-disordered breathing.

STUDY OBJECTIVES: Children with snoring and mild sleep-disordered breathing may be at increased risk for neurocognitive deficits despite few obstructive events. We hypothesized that actigraphy-based sleep duration and continuity associate with neurobehavioral functioning and explored whether these associations vary by demographic and socioeconomic factors. METHODS: 298 children enrolled in the Pediatric Adenotonsillectomy Trial, ages 3 to 12.9 years, 47.3% from racial or ethnic minority groups, with habitual snoring and an apnea-hypopnea index < 3 were studied with actigraphy (mean 7.5 ± 1.4 days) and completed a computerized vigilance task (Go-No-Go) and a test of fine motor control (9-Hole Pegboard). Caregivers completed the Behavior Rating Inventory of Executive Function. Regression analyses evaluated associations between sleep exposures (24-hour and nocturnal sleep duration, sleep fragmentation index, sleep efficiency) with the Behavior Rating Inventory of Executive Function Global Executive Composite index, pegboard completion time (fine motor control), and vigilance (d prime on the Go-No-Go), adjusting for demographic factors and study design measures. RESULTS: Longer sleep duration, higher sleep efficiency, and lower sleep fragmentation were associated with better executive function; each additional hour of sleep over 24 hours associated with more than a 3-point improvement in executive function (P = .002). Longer nocturnal sleep (P = .02) and less sleep fragmentation (P = .001) were associated with better fine motor control. Stronger associations were observed for boys and children less than 6 years old. CONCLUSIONS: Sleep quantity and continuity are associated with neurocognitive functioning in children with mild sleep-disordered breathing, supporting efforts to target these sleep health parameters as part of interventions for reducing neurobehavioral morbidity. CLINICAL TRIAL REGISTRATION: Registry: ClinicalTrials.gov; Name: Pediatric Adenotonsillectomy for Snoring (PATS); URL: https://clinicaltrials.gov/ct2/show/NCT02562040; Identifier: NCT02562040. CITATION: Robinson KA, Wei Z, Radcliffe J, et al. Associations of actigraphy measures of sleep duration and continuity with executive function, vigilance, and fine motor control in children with snoring and mild sleep-disordered breathing. J Clin Sleep Med. 2023;19(9):1595-1603.

Arap1 loss causes retinal pigment epithelium phagocytic dysfunction and subsequent photoreceptor death.

Retinitis pigmentosa (RP), a retinal degenerative disease, is the leading cause of heritable blindness. Previously, we described that Arap1-/- mice develop a similar pattern of photoreceptor degeneration. Arap1 is an Arf-directed GTPase-activating protein shown to modulate actin cytoskeletal dynamics. Curiously, Arap1 expression was detected in Müller glia and retinal pigment epithelium (RPE), but not the photoreceptors themselves. In this study, we generated conditional knockout mice for Müller glia/RPE, Müller glia and RPE via targeting Rlbp1, Glast and Vmd2 promoters, respectively, to drive Cre recombinase expression to knock out Arap1. Vmd2-Cre Arap1tm1c/tm1c and Rlbp1-Cre Arap1tm1c/tm1c mice, but not Glast-Cre Arap1tm1c/tm1c mice, recapitulated the phenotype originally observed in germline Arap1-/- mice. Mass spectrometry analysis of human ARAP1 co-immunoprecipitation identified candidate binding partners of ARAP1, revealing potential interactants involved in phagocytosis, cytoskeletal composition, intracellular trafficking and endocytosis. Quantification of outer segment phagocytosis in vivo demonstrated a clear phagocytic defect in Arap1-/- mice compared to Arap1+/+ controls. We conclude that Arap1 expression in RPE is necessary for photoreceptor survival due to its indispensable function in RPE phagocytosis. This article has an associated First Person interview with the first author of the paper.

Cytoglobin deficiency potentiates Crb1-mediated retinal degeneration in rd8 mice.

PURPOSE: The purpose of this study is to determine the effect of Cytoglobin (Cygb) deficiency on Crb1-related retinopathy. The Crb1 cell polarity complex is required for photoreceptor function and survival. Crb1-related retinopathies encompass a broad range of phenotypes which are not completely explained by the variability of Crb1 mutations. Genes thought to modify Crb1 function are therefore important targets of research. The biological function of Cygb involves oxygen delivery, scavenging of reactive oxygen species, and nitric oxide metabolism. However, the relationship of Cygb to diseases involving the Crb1 cell polarity complex is unknown. METHODS: Cygb knockout mice homozygous for the rd8 mutation (Cygb-/-rd8/rd8) were screened for ocular abnormalities and imaged using optical coherence tomography and fundus photography. Electroretinography was performed, as was histology and immunohistochemistry. Quantitative PCR was used to determine the effect of Cygb deficiency on transcription of Crb1 related cell polarity genes. RESULTS: Cygb-/-rd8/rd8 mice develop an abnormal retina with severe lamination abnormalities. The retina undergoes progressive degeneration with the ventral retina more severely affected than the dorsal retina. Cygb expression is in neurons of the retinal ganglion cell layer and inner nuclear layer. Immunohistochemical studies suggest that cell death predominates in the photoreceptors. Electroretinography amplitudes show reduced a- and b-waves, consistent with photoreceptor disease. Cygb deficient retinas had only modest transcriptional perturbations of Crb1-related cell polarity genes. Cygb-/- mice without the rd8 mutation did not exhibit obvious retinal abnormalities. CONCLUSIONS: Cygb is necessary for retinal lamination, maintenance of cell polarity, and photoreceptor survival in rd8 mice. These results are consistent with Cygb as a disease modifying gene in Crb1-related retinopathy. Further studies are necessary to investigate the role of Cygb in the human retina.

Impeding DNA Break Repair Enables Oocyte Quality Control.

Oocyte quality control culls eggs with defects in meiosis. In mouse, oocyte death can be triggered by defects in chromosome synapsis and recombination, which involve repair of DNA double-strand breaks (DSBs) between homologous chromosomes. We show that RNF212, a SUMO ligase required for crossing over, also mediates oocyte quality control. Both physiological apoptosis and wholesale oocyte elimination in meiotic mutants require RNF212. RNF212 sensitizes oocytes to DSB-induced apoptosis within a narrow window as chromosomes desynapse and cells transition into quiescence. Analysis of DNA damage during this transition implies that RNF212 impedes DSB repair. Consistently, RNF212 is required for HORMAD1, a negative regulator of inter-sister recombination, to associate with desynapsing chromosomes. We infer that oocytes impede repair of residual DSBs to retain a "memory" of meiotic defects that enables quality-control processes. These results define the logic of oocyte quality control and suggest RNF212 variants may influence transmission of defective genomes.

Arap1 Deficiency Causes Photoreceptor Degeneration in Mice.

Purpose: Small guanosine triphosphatase (GTPase) ADP-ribosylation factors (Arfs) regulate membrane traffic and actin reorganization under the control of GTPase-activating proteins (GAPs). Arap1 is an Arf-directed GAP that inhibits the trafficking of epidermal growth factor receptor (EGFR) to the early endosome, but the diversity of its functions is incompletely understood. The aim of this study was to determine the role of Arap1 in the mammalian retina. Methods: Genetically engineered Arap1 knockout mice were screened for ocular abnormalities in the National Institutes of Health Knockout Mouse Production and Phenotyping (KOMP2) Project. Arap1 knockout and wild-type eyes were imaged using optical coherence tomography and fundus photography, and analyzed by immunohistochemistry. Results: Arap1-/- mice develop a normal appearing retina, but undergo photoreceptor degeneration starting at 4 weeks postnatal age. The fundus appearance of mutants is notable for pigmentary changes, optic nerve pallor, vascular attenuation, and outer retinal thinning, reminiscent of retinitis pigmentosa in humans. Immunohistochemical studies suggest the cell death is predominantly in the outer nuclear layer. Functional evaluation of the retina by electroretinography reveals amplitudes are reduced. Arap1 is detected most notably in Müller glia, and not in photoreceptors, implicating a role for Müller glia in photoreceptor survival. Conclusions: Arap1 is necessary for normal photoreceptor survival in mice, and may be a novel gene relevant to human retinal degenerative processes, although its mechanism is unknown. Further studies in this mouse model of retinal degeneration will give insights into the cellular functions and signaling pathways in which Arap1 participates.