Perturbing the ubiquitin pathway reveals how mitosis is hijacked to denucleate and regulate cell proliferation and differentiation in vivo.

Background: The eye lens presents a unique opportunity to explore roles for specific molecules in cell proliferation, differentiation and development because cells remain in place throughout life and, like red blood cells and keratinocytes, they go through the most extreme differentiation, including removal of nuclei and cessation of protein synthesis. Ubiquitination controls many critical cellular processes, most of which require specific lysines on ubiquitin (Ub). Of the 7 lysines (K) least is known about effects of modification of K6.

Alzheimer's disease amyloid-beta links lens and brain pathology in Down syndrome.

Down syndrome (DS, trisomy 21) is the most common chromosomal disorder and the leading genetic cause of intellectual disability in humans. In DS, triplication of chromosome 21 invariably includes the APP gene (21q21) encoding the Alzheimer's disease (AD) amyloid precursor protein (APP). Triplication of the APP gene accelerates APP expression leading to cerebral accumulation of APP-derived amyloid-beta peptides (Abeta), early-onset AD neuropathology, and age-dependent cognitive sequelae.

Multiple and additive functions of ALDH3A1 and ALDH1A1: cataract phenotype and ocular oxidative damage in Aldh3a1(-/-)/Aldh1a1(-/-) knock-out mice.

ALDH3A1 (aldehyde dehydrogenase 3A1) is abundant in the mouse cornea but undetectable in the lens, and ALDH1A1 is present at lower (catalytic) levels in the cornea and lens. To test the hypothesis that ALDH3A1 and ALDH1A1 protect the anterior segment of the eye against environmentally induced oxidative damage, Aldh1a1(-/-)/Aldh3a1(-/-) double knock-out and Aldh1a1(-/-) and Aldh3a1(-/-) single knock-out mice were evaluated for biochemical changes and cataract formation (lens opacification). The Aldh1a1/Aldh3a1- and Aldh3a1-null mice develop cataracts in the anterior and posterior subcapsular regions as well as punctate opacities in the cortex by 1 month of age.

Age-related cataracts in alpha3Cx46-knockout mice are dependent on a calpain 3 isoform.

Purpose: Previous studies have demonstrated that in 129alpha3Cx46-/- mice, age-related nuclear cataract is formed. In the present study, a more in vivo-relevant model was generated to test the hypothesis that the calpain 3 gene is involved in age-related nuclear cataractogenesis in alpha3Cx46 knockout mice.

Methods: To test the hypothesis that the calpain 3 gene is involved in age-related nuclear cataractogenesis in alpha3Cx46 knockout mice, 129alpha3Cx46-/- and CAPN3-/- mice were mated to generate homozygous double-knockout (dKO) mice.

Transgenic overexpression of connexin50 induces cataracts.

To examine the effects of increased expression of Cx50 in the mouse lens, transgenic mice were generated using a DNA construct containing the human Cx50 coding region and a C-terminal FLAG epitope driven by the chicken betaB1-crystallin promoter. Expression of this protein in paired Xenopus oocytes induced gap junctional currents of similar magnitude to wild type human Cx50. Three lines of transgenic mice expressing the transgenic protein were analyzed.

Computer modeling of secondary fiber development and growth: I. Nonprimate lenses.

Purpose: The purpose of this study was to use qualitative and quantitative structural data from nonprimate lenses with branched (Y and line) sutures to generate computer models (animations) of secondary fiber development and suture formation.

Methods: A minimum of 12-18 adult lenses/species (mice, cows, frogs, and rabbits) were used in this study. Lenses were analyzed by light (LM), transmission (TEM), and scanning electron microscopy (SEM).

Development of lens sutures.

Cylindrical map projections (CMPs) have been used for centuries as an effective means of plotting the features of a 3D spheroidal surfaces (e.g. the earth) on a 2D rectangular map.

Lens structure in MIP-deficient mice.

In this study we used correlative light, scanning, and transmission (freeze-etch) electron microscopy to characterize lens structure in normal mice and compare it with that in mice deficient in the major intrinsic protein (MIP) of fiber cells. Grossly, wild-type lenses were transparent and had typical Y sutures at all of the ages examined. These lenses had fibers of uniform shape (hexagonal in cross section) arranged in ordered concentric growth shells and radial cell columns.

Morphology and organization of posterior fiber ends during migration.

Purpose: To characterize structural parameters of the basal membrane complex (BMC) and to determine the arrangement and organization of posterior fiber ends during elongation/migration in lenses with branched sutures.

Methods: Lenses from normal, juvenile (4-6 week old) Sprague-Dawley rats (n=16) were utilized. Posterior fiber ends were assessed on both whole mounts of lens capsules and on decapsulated lenses.

Knockout of the intermediate filament protein CP49 destabilises the lens fibre cell cytoskeleton and decreases lens optical quality, but does not induce cataract.

In this report, the phenotype associated with the first targeted knockout of the lens specific intermediate filament gene CP49 is described. Several surprising observations have been made. The first was that no cataract was observed despite the fact that the beaded filaments of the lens fibre cells had been disrupted.