0000000000179763
AUTHOR
Ingrid Koziollek-drechsler
Heterodimer formation of wild-type and amyotrophic lateral sclerosis-causing mutant Cu/Zn-superoxide dismutase induces toxicity independent of protein aggregation
Recent studies provide evidence that wild-type Cu/Zn-superoxide dismutase (SOD1(hWT)) might be an important factor in mutant SOD1-mediated amyotrophic lateral sclerosis (ALS). In order to investigate its functional role in the pathogenesis of ALS, we designed fusion proteins of two SOD1 monomers linked by a polypeptide. We demonstrated that wild-type-like mutants, but not SOD1(G85R) homodimers, as well as mutant heterodimers including SOD1(G85R)-SOD1(hWT) display dismutase activity. Mutant homodimers showed an increased aggregation compared with the corresponding heterodimers in cell cultures and transgenic Caenorhabditis elegans, although SOD1(G85R) heterodimers are more toxic in functiona…
Wild-type Cu/Zn superoxide dismutase (SOD1) does not facilitate, but impedes the formation of protein aggregates of amyotrophic lateral sclerosis causing mutant SOD1
Aggregation of Cu/Zn superoxide dismutase (SOD1) is a hallmark of a subset of familial amyotrophic lateral sclerosis (ALS) cases. The expression of wild-type SOD1 [SOD(hWT)] surprisingly exacerbates the phenotype of mutant SOD1 in vivo. Here we studied whether SOD1(hWT) may affect mutant SOD1 aggregation by employing fluorescence microscopy techniques combined with lifetime-based Förster resonance energy transfer (FRET). Only a very minor fraction of SOD1(hWT) was observed in aggregates induced by mutant SOD1(G37R), SOD1(G85R) or SOD1(G93C). Quite in contrast, co-expression of SOD(hWT) reduced the amount of mutant SOD1 in the aggregate fraction. Furthermore, we did not detect endogenous mou…
The expression level of GCNF affects fate choice during neural differentiation of PCC7 cells
The nuclear receptor GCNF (NR6A1) is required for embryonic survival and development, and regulation of fertility. We used a transgenic approach to investigate its role in neural differentiation. As model we chose the embryonal carcinoma cell line PCC7, which reproducibly differentiates into a tissue-like pattern of neuronal and non-neuronal cells after exposure to retinoic acid (RA). The differentiation pattern of gcnf sense and antisense clones consistently indicated that the expression level of GCNF positively correlated with the development of the neuronal fate. Moreover, antisense clones failed to down-regulate expression of the key regulator of differentiation Oct4 during the initial …
Estrogen receptor α regulates non-canonical autophagy that provides stress resistance to neuroblastoma and breast cancer cells and involves BAG3 function
AbstractBreast cancer is a heterogeneous disease and approximately 70% of newly diagnosed breast cancers are estrogen receptor (ER) positive. Out of the two ER types, α and β, ERα is the only ER that is detectable by immunohistochemistry in breast cancer biopsies and is the predominant subtype expressed in breast tumor tissue. ER-positive tumors are currently treated with anti-hormone therapy to inhibit ER signaling. It is well known that breast cancer cells can develop endocrine resistance and resistance to anti-hormone therapy and this can be facilitated via the autophagy pathway, but so far the description of a detailed autophagy expression profile of ER-positive cancer cells is missing.…
RAB3GAP1 and RAB3GAP2 modulate basal and rapamycin-induced autophagy
Macroautophagy is a degradative pathway that sequesters and transports cytosolic cargo in autophagosomes to lysosomes, and its deterioration affects intracellular proteostasis. Membrane dynamics accompanying autophagy are mostly elusive and depend on trafficking processes. RAB GTPase activating proteins (RABGAPs) are important factors for the coordination of cellular vesicle transport systems, and several TBC (TRE2-BUB2-CDC16) domain-containing RABGAPs are associated with autophagy. Employing C. elegans and human primary fibroblasts, we show that RAB3GAP1 and RAB3GAP2, which are components of the TBC domain-free RAB3GAP complex, influence protein aggregation and affect autophagy at basal an…
Dimerization of visinin-like protein 1 is regulated by oxidative stress and calcium and is a pathological hallmark of amyotrophic lateral sclerosis
AbstractRedox control of proteins that form disulfide bonds upon oxidative challenge is an emerging topic in the physiological and pathophysiological regulation of protein function. We have investigated the role of the neuronal calcium sensor protein visinin-like protein 1 (VILIP-1) as a novel redox sensor in a cellular system. We have found oxidative stress to trigger dimerization of VILIP-1 within a cellular environment and identified thioredoxin reductase as responsible for facilitating the remonomerization of the dimeric protein. Dimerization is modulated by calcium and not dependent on the myristoylation of VILIP-1. Furthermore, we show by site-directed mutagenesis that dimerization is…
Wild-type Cu/Zn superoxide dismutase stabilizes mutant variants by heterodimerization
Mutations in the gene encoding Cu/Zn superoxide dismutase (SOD1) are responsible for a subset of amyotrophic lateral sclerosis cases presumably by the acquisition of as yet unknown toxic properties. Additional overexpression of wild-type SOD1 in mutant SOD1 transgenic mice did not improve but rather accelerated the disease course. Recently, it was documented that the presence of wild-type SOD1 (SOD(WT)) reduced the aggregation propensity of mutant SOD1 by the formation of heterodimers between mutant and SOD1(WT) and that these heterodimers displayed at least a similar toxicity in cellular and animal models. In this study we investigated the biochemical and biophysical properties of obligate…
RAB3GAP1 and RAB3GAP2 modulate basal and rapamycin-induced autophagy
Macroautophagy is a degradative pathway that sequesters and transports cytosolic cargo in autophagosomes to lysosomes, and its deterioration affects intracellular proteostasis. Membrane dynamics accompanying autophagy are mostly elusive and depend on trafficking processes. RAB GTPase-activating proteins (RABGAPs) are important factors for the coordination of cellular vesicle transport systems, and several TBC (TRE2-BUB2-CDC16) domain-containing RABGAPs are associated with autophagy. Employing C. elegans and human primary fibroblasts, we show that RAB3GAP1 and RAB3GAP2, which are components of the TBC domain-free RAB3GAP complex, influence protein aggregation and affect autophagy at basal an…