Genome-wide screening of mouse knockouts reveals novel genes required for normal integumentary and oculocutaneous structure and function.

Oculocutaneous syndromes are often due to mutations in single genes. In some cases, mouse models for these diseases exist in spontaneously occurring mutations, or in mice resulting from forward mutatagenesis screens. Here we present novel genes that may be causative for oculocutaneous disease in humans, discovered as part of a genome-wide screen of knockout-mice in a targeted single-gene deletion project. The International Mouse Phenotyping Consortium (IMPC) database (data release 10.0) was interrogated for all mouse strains with integument abnormalities, which were then cross-referenced individually to identify knockouts with concomitant ocular abnormalities attributed to the same targeted gene deletion. The search yielded 307 knockout strains from unique genes with integument abnormalities, 226 of which have not been previously associated with oculocutaneous conditions. Of the 307 knockout strains with integument abnormalities, 52 were determined to have ocular changes attributed to the targeted deletion, 35 of which represent novel oculocutaneous genes. Some examples of various integument abnormalities are shown, as well as two examples of knockout strains with oculocutaneous phenotypes. Each of the novel genes provided here are potentially relevant to the pathophysiology of human integumentary, or oculocutaneous conditions, such as albinism, phakomatoses, or other multi-system syndromes. The novel genes reported here may implicate molecular pathways relevant to these human diseases and may contribute to the discovery of novel therapeutic targets

Genome-wide screening reveals the genetic basis of mammalian embryonic eye development.

BACKGROUND: Microphthalmia, anophthalmia, and coloboma (MAC) spectrum disease encompasses a group of eye malformations which play a role in childhood visual impairment. Although the predominant cause of eye malformations is known to be heritable in nature, with 80% of cases displaying loss-of-function mutations in the ocular developmental genes OTX2 or SOX2, the genetic abnormalities underlying the remaining cases of MAC are incompletely understood. This study intended to identify the novel genes and pathways required for early eye development. Additionally, pathways involved in eye formation during embryogenesis are also incompletely understood. This study aims to identify the novel genes and pathways required for early eye development through systematic forward screening of the mammalian genome. RESULTS: Query of the International Mouse Phenotyping Consortium (IMPC) database (data release 17.0, August 01, 2022) identified 74 unique knockout lines (genes) with genetically associated eye defects in mouse embryos. The vast majority of eye abnormalities were small or absent eyes, findings most relevant to MAC spectrum disease in humans. A literature search showed that 27 of the 74 lines had previously published knockout mouse models, of which only 15 had ocular defects identified in the original publications. These 12 previously published gene knockouts with no reported ocular abnormalities and the 47 unpublished knockouts with ocular abnormalities identified by the IMPC represent 59 genes not previously associated with early eye development in mice. Of these 59, we identified 19 genes with a reported human eye phenotype. Overall, mining of the IMPC data yielded 40 previously unimplicated genes linked to mammalian eye development. Bioinformatic analysis showed that several of the IMPC genes colocalized to several protein anabolic and pluripotency pathways in early eye development. Of note, our analysis suggests that the serine-glycine pathway producing glycine, a mitochondrial one-carbon donator to folate one-carbon metabolism (FOCM), is essential for eye formation. CONCLUSIONS: Using genome-wide phenotype screening of single-gene knockout mouse lines, STRING analysis, and bioinformatic methods, this study identified genes heretofore unassociated with MAC phenotypes providing models to research novel molecular and cellular mechanisms involved in eye development. These findings have the potential to hasten the diagnosis and treatment of this congenital blinding disease

A large scale hearing loss screen reveals an extensive unexplored genetic landscape for auditory dysfunction

The developmental and physiological complexity of the auditory system is likely reflected in the underlying set of genes involved in auditory function. In humans, over 150 non-syndromic loci have been identified, and there are more than 400 human genetic syndromes with a hearing loss component. Over 100 non-syndromic hearing loss genes have been identified in mouse and human, but we remain ignorant of the full extent of the genetic landscape involved in auditory dysfunction. As part of the International Mouse Phenotyping Consortium, we undertook a hearing loss screen in a cohort of 3006 mouse knockout strains. In total, we identify 67 candidate hearing loss genes. We detect known hearing loss genes, but the vast majority, 52, of the candidate genes were novel. Our analysis reveals a large and unexplored genetic landscape involved with auditory function

Comprehensive ECG reference intervals in C57BL/6N substrains provide a generalizable guide for cardiac electrophysiology studies in mice.

Reference ranges provide a powerful tool for diagnostic decision-making in clinical medicine and are enormously valuable for understanding normality in pre-clinical scientific research that uses in vivo models. As yet, there are no published reference ranges for electrocardiography (ECG) in the laboratory mouse. The first mouse-specific reference ranges for the assessment of electrical conduction are reported herein generated from an ECG dataset of unprecedented scale. International Mouse Phenotyping Consortium data from over 26,000 conscious or anesthetized C57BL/6N wildtype control mice were stratified by sex and age to develop robust ECG reference ranges. Interesting findings include that heart rate and key elements from the ECG waveform (RR-, PR-, ST-, QT-interval, QT corrected, and QRS complex) demonstrate minimal sexual dimorphism. As expected, anesthesia induces a decrease in heart rate and was shown for both inhalation (isoflurane) and injectable (tribromoethanol) anesthesia. In the absence of pharmacological, environmental, or genetic challenges, we did not observe major age-related ECG changes in C57BL/6N-inbred mice as the differences in the reference ranges of 12-week-old compared to 62-week-old mice were negligible. The generalizability of the C57BL/6N substrain reference ranges was demonstrated by comparison with ECG data from a wide range of non-IMPC studies. The close overlap in data from a wide range of mouse strains suggests that the C57BL/6N-based reference ranges can be used as a robust and comprehensive indicator of normality. We report a unique ECG reference resource of fundamental importance for any experimental study of cardiac function in mice

A large scale hearing loss screen reveals an extensive unexplored genetic landscape for auditory dysfunction.

The developmental and physiological complexity of the auditory system is likely reflected in the underlying set of genes involved in auditory function. In humans, over 150 non-syndromic loci have been identified, and there are more than 400 human genetic syndromes with a hearing loss component. Over 100 non-syndromic hearing loss genes have been identified in mouse and human, but we remain ignorant of the full extent of the genetic landscape involved in auditory dysfunction. As part of the International Mouse Phenotyping Consortium, we undertook a hearing loss screen in a cohort of 3006 mouse knockout strains. In total, we identify 67 candidate hearing loss genes. We detect known hearing loss genes, but the vast majority, 52, of the candidate genes were novel. Our analysis reveals a large and unexplored genetic landscape involved with auditory function.The full extent of the genetic basis for hearing impairment is unknown. Here, as part of the International Mouse Phenotyping Consortium, the authors perform a hearing loss screen in 3006 mouse knockout strains and identify 52 new candidate genes for genetic hearing loss

Using Stubble Height to Monitor Riparian Vegetation

The Rangelands archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform March 202

Arap1 Deficiency Causes Photoreceptor Degeneration in Mice.

PurposeSmall 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.MethodsGenetically 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.ResultsArap1-/- 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.ConclusionsArap1 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

Arap1 Deficiency Causes Photoreceptor Degeneration in Mice.

PurposeSmall 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.MethodsGenetically 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.ResultsArap1-/- 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.ConclusionsArap1 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

Arap1 Deficiency Causes Photoreceptor Degeneration in Mice.

PurposeSmall 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.MethodsGenetically 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.ResultsArap1-/- 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.ConclusionsArap1 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

A Population Study of Common Ocular Abnormalities in C57BL/6N rd8 Mice

International audiencePurpose: The purpose of this study was to quantify the frequency and severity of ocular abnormalities affecting wild-type C57BL/6N mice, the most common strain used worldwide for the creation of single-gene knockouts.Methods: A total of 2773 animals (5546 eyes) were examined at one colony at UC Davis and in three more colonies at the Institut Clinique de la Souris in Strasbourg, France. Mice were examined at 15 to 16 weeks postnatal age by performing anterior segment biomicroscopy, posterior segment examination by indirect ophthalmoscopy, intraocular pressure measurement, and optical coherence tomography of anterior and posterior segment structures.Results: Common ocular findings in the C57BL/6N strain included corneal deposits (3%), increased optical density of the anterior lens capsule (67%), punctate nuclear cataracts (98%), vitreous crystalline deposits (61%), hyaloid vascular remnant (6%), and retinal dysplasia attributed to the rd8 mutation (58%). Interestingly, retinal dysplasia was more common in male mice in all four breeding colonies evaluated in this study. The thickness of ocular tissues and compartments were measured by spectral-domain optical coherence tomography, including the central cornea, anterior chamber, vitreous, and retinal layers. Intraocular pressure was measured by rebound tonometry.Conclusions: Ocular abnormalities are common in anterior and posterior segments of the C57BL/6N mouse, the most common background on which single-gene knockout mice have been made. It is important that vision scientists understand the extent and variability of ocular findings associated with this particular genetic background of mice