Reductive stress promotes protein aggregation and impairs neurogenesis.

Redox homeostasis regulates key cellular signaling in both physiology and pathology. While perturbations result in shifting the redox homeostasis towards oxidative stress are well documented, the influence of reductive stress (RS) in neurodegenerative diseases and its mechanisms are unknown. Here, we postulate that a redox shift towards the reductive arm (through the activation of Nrf2 signaling) will damage neurons and impair neurogenesis.

A Novel Glycogen Synthase Kinase-3 Inhibitor Optimized for Acute Myeloid Leukemia Differentiation Activity.

Standard therapies used for the treatment of acute myeloid leukemia (AML) are cytotoxic agents that target rapidly proliferating cells. Unfortunately, this therapeutic approach has limited efficacy and significant toxicity and the majority of AML patients still die of their disease. In contrast to the poor prognosis of most AML patients, most individuals with a rare subtype of AML, acute promyelocytic leukemia, can be cured by differentiation therapy using regimens containing all-trans retinoic acid.

Identification of a Small Molecule That Overcomes HdmX-Mediated Suppression of p53.

Inactivation of the p53 tumor suppressor by mutation or overexpression of negative regulators occurs frequently in cancer. As p53 plays a key role in regulating proliferation or apoptosis in response to DNA-damaging chemotherapies, strategies aimed at reactivating p53 are increasingly being sought. Strategies to reactivate wild-type p53 include the use of small molecules capable of releasing wild-type p53 from key, cellular negative regulators, such as Hdm2 and HdmX.

Disruption of nuclear factor (erythroid-derived-2)-like 2 antioxidant signaling: a mechanism for impaired activation of stem cells and delayed regeneration of skeletal muscle.

Recently we have reported that age-dependent decline in antioxidant levels accelerated apoptosis and skeletal muscle degeneration. Here, we demonstrate genetic ablation of the master cytoprotective transcription factor, nuclear factor (erythroid-derived-2)-like 2 (Nrf2), aggravates cardiotoxin (CTX)-induced tibialis anterior (TA) muscle damage. Disruption of Nrf2 signaling sustained the CTX-induced burden of reactive oxygen species together with compromised expression of antioxidant genes and proteins.

Response: Contributions of the Myf5-independent lineage to myogenesis.

In this issue, Comai et al. present evidence that previous support for Myf5-independent myogenic cell lineages was confounded by inefficiencies in lineage marking and ablation. Here, Haldar et al.

Disruption of Nrf2/ARE signaling impairs antioxidant mechanisms and promotes cell degradation pathways in aged skeletal muscle.

Age-associated decline in antioxidant potential and accumulation of reactive oxygen/nitrogen species are primary causes for multiple health problems, including muscular dystrophy and sarcopenia. The role of the nuclear erythroid-2-p45-related factor-2 (Nrf2) signaling has been implicated in antioxidant gene regulation. Here, we investigated the loss-of-function mechanisms for age-dependent regulation of Nrf2/ARE (Antioxidant Response Element) signaling in skeletal muscle (SM).

Mutant prominin 1 found in patients with macular degeneration disrupts photoreceptor disk morphogenesis in mice.

Familial macular degeneration is a clinically and genetically heterogeneous group of disorders characterized by progressive central vision loss. Here we show that an R373C missense mutation in the prominin 1 gene (PROM1) causes 3 forms of autosomal-dominant macular degeneration. In transgenic mice expressing R373C mutant human PROM1, both mutant and endogenous PROM1 were found throughout the layers of the photoreceptors, rather than at the base of the photoreceptor outer segments, where PROM1 is normally localized.

A small region in the angiotensin-converting enzyme distal ectodomain is required for cleavage-secretion of the protein at the plasma membrane.

Both germinal and somatic isoforms of ACE are type I ectoproteins expressed on the cell surface from where the enzymatically active ectodomains are released to circulation by a regulated cleavage-secretion process. Our previous studies have shown that ACE-secretase activity is regulated by the ACE distal ectodomain and not by sequences at or around the cleavage site. In the current study we have identified that the ACE residues encompassing 343 to 655 of the germinal form are needed for its cleavage-secretion.

Two cell lineages, myf5 and myf5-independent, participate in mouse skeletal myogenesis.

In skeletal muscle development, the myogenic regulatory factors myf5 and myoD play redundant roles in the specification and maintenance of myoblasts, whereas myf6 has a downstream role in differentiating myocytes and myofibers. It is not clear whether the redundancy between myf5 and myoD is within the same cell lineage or between distinct lineages. Using lineage tracing and conditional cell ablation in mice, we demonstrate the existence of two distinct lineages in myogenesis: a myf5 lineage and a myf5-independent lineage.

Elovl4 haploinsufficiency does not induce early onset retinal degeneration in mice.

ELOVL4 was first identified as a disease-causing gene in Stargardt macular dystrophy (STGD3, MIM 600110.) To date, three ELOVL4 mutations have been identified, all of which result in truncated proteins which induce autosomal dominant juvenile macular degenerations. Based on sequence homology, ELOVL4 is thought to be another member within a family of proteins functioning in the elongation of long chain fatty acids.

Loss of ER retention and sequestration of the wild-type ELOVL4 by Stargardt disease dominant negative mutants.

Purpose: Mutations in ELOVL4, a member of the fatty acid elongase (ELO) family, are responsible for autosomal dominant Stargardt-like macular degeneration. The specific role of ELOVL4 in photoreceptors and the degenerative events induced by dominant ELOVL4 mutations are not well understood. As a first step to identifying possible mechanisms contributing to cellular dysfunction, we transfected HEK293 and COS cells with fluorescent-labeled wild-type and mutant ELOVL4 constructs.

Purification of streptomycin adenylyltransferase from a recombinant Escherichia coli.

Bacterial resistance to aminoglycosides continues to escalate and is widely recognized as a serious health threat, contributing to interest in understanding the mechanisms of resistance. One important mechanism of streptomycin modification is through ATP dependent O-adenylation, catalyzed by streptomycin adenylyltransferase (SMATase). The aim of this study was to purify the recombinant SMATase by Ni(2+)-IDA-His bind resin column chromatography.

Mutant carbonic anhydrase 4 impairs pH regulation and causes retinal photoreceptor degeneration.

Retina and retinal pigment epithelium (RPE) belong to the metabolically most active tissues in the human body. Efficient removal of acid load from retina and RPE is a critical function mediated by the choriocapillaris. However, the mechanism by which pH homeostasis is maintained is largely unknown.

A novel mutation in the ELOVL4 gene causes autosomal dominant Stargardt-like macular dystrophy.

Purpose: To conduct clinical and genetic studies in a European family with autosomal dominant Stargardt-like macular dystrophy (adSTGD-like MD) and to investigate the functional consequences of a novel ELOVL4 mutation.

Methods: Ophthalmic examination and mutation screening by direct sequencing of the ELOVL4 gene was performed in two affected individuals. Wild-type and mutant ELOVL4 genes were expressed as enhanced green fluorescent protein (EGFP) fusion proteins in transient transfection in NIH-3T3 and HEK293 cells.

A novel RDS/peripherin gene mutation associated with diverse macular phenotypes.

Pattern dystrophy is a heterogeneous group of retinal dystrophies of which butterfly-shaped pattern dystrophy (BPD) and adult-onset foveomacular dystrophy (AOFMD) are the two most common forms. BPD is characterized by a butterfly-shaped, irregular, depigmented lesion at the level of the retinal pigment epithelium. In contrast, AOFMD is characterized by the presence of slightly elevated, symmetric, solitary, round to oval, yellow lesions at the level of the retinal pigment epithelium.

Expression of wild type and mutant ELOVL4 in cell culture: subcellular localization and cell viability.

Purpose: ELOVL4 is a member of the fatty acid elongase (ELO) family of genes. Mutations of this gene are responsible for autosomal dominant Stargardt-like macular degeneration. However, the specific role of ELOVL4 in photoreceptor cells and the mechanism by which mutations in ELOVL4 causes macular degeneration are not known.

Elovl4 mRNA distribution in the developing mouse retina and phylogenetic conservation of Elovl4 genes.

Purpose: Stargardt-like macular dystrophy (STGD3) is an autosomal dominant form of early onset macular degeneration. The disease causing gene ELOVL4 encodes a protein that belongs to a family of proteins functioning in elongation of long chain fatty acids. The purpose of this study is to characterize cross-species conservation of ELOVL4 and investigate its mRNA distribution in the developing mouse eye.