SANS (USH1G) expression in developing and mature mammalian retina

AbstractThe human Usher syndrome (USH) is the most common form of combined deaf-blindness. Usher type I (USH1), the most severe form, is characterized by profound congenital deafness, constant vestibular dysfunction and prepubertal-onset of retinitis pigmentosa. Five corresponding genes of the six USH1 genes have been cloned so far. The USH1G gene encodes the SANS (scaffold protein containing ankyrin repeats and SAM domain) protein which consists of protein motifs known to mediate protein–protein interactions. Recent studies indicated SANS function as a scaffold protein in the protein interactome related to USH.Here, we generated specific antibodies for SANS protein expression analyses. Our study revealed SANS protein expression in NIH3T3 fibroblasts, murine tissues containing ciliated cells and in mature and developing mammalian retinas. In mature retinas, SANS was localized in inner and outer plexiform retinal layers, and in the photoreceptor cell layer. Subcellular fractionations, tangential cryosections and immunocytochemistry revealed SANS in synaptic terminals, cell–cell adhesions of the outer limiting membrane and ciliary apparati of photoreceptor cells. Analyses of postnatal developmental stages of murine retinas demonstrated SANS localization in differentiating ciliary apparati and in fully developed cilia, synapses, and cell–cell adhesions of photoreceptor cells.Present data provide evidence that SANS functions as a scaffold protein in USH protein networks during ciliogenesis, at the mature ciliary apparatus, the ribbon synapse and the cell–cell adhesion of mammalian photoreceptor cells. Defects of SANS may cause dysfunction of the entire network leading to retinal degeneration, the ocular symptom characteristic for USH patients

Impact of gain dispersion on the spatio-temporal dynamics of multisection lasers

We present a refined model for multi-section lasers, introducing an additional equation for material polarization in the well known travelling wave model. We investigate the polarization-induced changes in the spectral properties of the optical waveguide. Finally, we show the relevance of this model for a more realistic simulation of complicated dynamical behaviour of multi-section Distributed Feedback (DFB)-Lasers, such as fast self-pulsations, multi-stability, and hysteresis effects due to mode competition

Dephosphorylation of Centrins by Protein Phosphatase 2C α and β

In the present study, we identified protein phosphatases dephosphorylating centrins previously phosphorylated by protein kinase CK2. The following phosphatases known to be present in the retina were tested: PP1, PP2A, PP2B, PP2C, PP5, and alkaline phosphatase. PP2C α and β were capable of dephosphorylating P-Thr138-centrin1 most efficiently. PP2Cδ was inactive and the other retinal phosphatases also had much less or no effect. Similar results were observed for centrins 2 and 4. Centrin3 was not a substrate for CK2. The results suggest PP2C α and β to play a significant role in regulating the phosphorylation status of centrins in vivo

Photoreceptor vitality in organotypic cultures of mature vertebrate retinas validated by light-dependent molecular movements

AbstractVertebrate photoreceptor cells are polarized neurons highly specialized for light absorption and visual signal transduction. Photoreceptor cells consist of the light sensitive outer segment and the biosynthetic active inner segment linked by a slender connecting cilium. The function of mature photoreceptor cells is strictly dependent on this compartmentalization which is maintained in the specialized retinal environment. To keep this fragile morphologic and functional composition for further cell biological studies and treatments we established organotypic retina cultures of mature mice and Xenopus laevis. The organotypic retina cultures of both model organisms are created as co-cultures of the retina and the pigment epithelium, still attached to outer segments of the photoreceptor cells. To demonstrate the suitability of the culture system for physiological analyses we performed apoptotic cell death analyses and verified photoreceptor viability. Furthermore, light-dependent bidirectional movements of arrestin and transducin in photoreceptors in vivo and in the retinal cultures were indistinguishable indicating normal photoreceptor cell-biologic function in organotypic cultures. Our established culture systems allow the analysis of mature photoreceptor cells and their accessibility to treatments, characteristic for common cell culture. Furthermore, this culturing technique also provides an appropriate system for gene delivery to retinal cells and will serve to simulate gene therapeutic approaches prior to difficult and time-consuming in vivo experiments

Improving the modulation bandwidth in semiconductor lasers by passive feedback

We explore the concept of passive-feedback lasers for direct signal modulation at 40 Gbit/s. Based on numerical simulation and bifurcation analysis, we explain the main mechanisms in these devices which are crucial for modulation at high speed. The predicted effects are demonstrated experimentally by means of correspondingly designed devices. In particular a significant improvement of the modulation bandwidth at low injection currents can be demonstrated

Der Arbeitsmarkt in der Bundesrepublik Deutschland 1979 (insgesamt und regional)

"Im Jahre 1978 entsprach die wirtschaftliche Entwicklung in der Bundesrepublik Deutschland (reales Bruttoinlandsprodukt + 3,5%) weitgehend dem, was vor Jahresfrist allgemein erwartet worden war. Die Zahl der Erwerbstätigen erhöhte sich um 50 000 Personen, die Zahl der registrierten Arbeitslosen ging leicht (- 37 000 Personen) auf 993 000 Personen zurück, die Stille Reserve blieb weiterhin in der Größenordnung von 650 000 Personen. In einem Alternativentableau für das Jahr 1979 wird dargestellt, wie sich unterschiedliche Wachstumsraten der Produktion auf Beschäftigung und Arbeitslosigkeit auswirken würden. Im Mittelpunkt steht die Variante, die vom Sozialproduktswachstum her gesehen heute weithin für die wahrscheinlichste gehalten wird (+ 4,0%). Sie bedeutet einen Anstieg der Zahl der Erwerbstätigen um 160 000 Personen und einen Rückgang der Zahl der Arbeitslosen um rund 70 000 auf 920 000 Personen. Im Falle eines rascheren Wirtschaftswachstums und/oder einer Verringerung der Arbeitszeit, die über das gegenwärtig erkennbare Maß hinausgeht, ließe sich ein wesentlich stärkerer Rückgang der Zahl der registrierten Arbeitslosen erreichen. In einem gesonderten Abschnitt werden die Auswirkungen dargestellt, die von den verschiedenen arbeitsmarktpolitischen Bemühungen der Bundesanstalt und der Gebietskörperschaften ausgegangen sind (Entlastung der Arbeitslosigkeit 1978 um 167 000 Personen, 1979 voraussichtlich um 180 000 Personen). Erstmals wird an dieser Stelle in einer Übersicht dargestellt, in welchem Umfang sowohl trendmäßige Entwicklungen als auch politische Maßnahmen zur Verringerung der Lebensarbeitszeit (mit der Folge einer beträchtlichen Entlastung des Arbeitsmarktes) beitragen. Ohne diese arbeitsmarktwirksamen Maßnahmen und Entwicklungen seit 1973 würde die Zahl der Arbeitslosen im Jahre 1979 um mehr als 1/2 Mio höher ausfallen als nun zu erwarten ist. Dieser Entlastungseffekt ist 1979 fast 100 000 Personen größer als im Vorjahr." (Autorenreferat)Arbeitsmarktentwicklung, regionaler Arbeitsmarkt, Arbeitszeitpolitik

Direct interaction of the Usher syndrome 1G protein SANS and myomegalin in the retina

AbstractThe human Usher syndrome (USH) is the most frequent cause of combined hereditary deaf-blindness. USH is genetically heterogeneous with at least 11 chromosomal loci assigned to 3 clinical types, USH1-3. We have previously demonstrated that all USH1 and 2 proteins in the eye and the inner ear are organized into protein networks by scaffold proteins. This has contributed essentially to our current understanding of the function of USH proteins and explains why defects in proteins of different families cause very similar phenotypes. We have previously shown that the USH1G protein SANS (scaffold protein containing ankyrin repeats and SAM domain) contributes to the periciliary protein network in retinal photoreceptor cells. This study aimed to further elucidate the role of SANS by identifying novel interaction partners. In yeast two-hybrid screens of retinal cDNA libraries we identified 30 novel putative interacting proteins binding to the central domain of SANS (CENT). We confirmed the direct binding of the phosphodiesterase 4D interacting protein (PDE4DIP), a Golgi associated protein synonymously named myomegalin, to the CENT domain of SANS by independent assays. Correlative immunohistochemical and electron microscopic analyses showed a co-localization of SANS and myomegalin in mammalian photoreceptor cells in close association with microtubules. Based on the present results we propose a role of the SANS-myomegalin complex in microtubule-dependent inner segment cargo transport towards the ciliary base of photoreceptor cells

Protein quality control during aging involves recruitment of the macroautophagy pathway by BAG3

The Hsc/Hsp70 co-chaperones of the BAG (Bcl-2-associated athanogene) protein family are modulators of protein quality control. We examined the specific roles of BAG1 and BAG3 in protein degradation during the aging process. We show that BAG1 and BAG3 regulate proteasomal and macroautophagic pathways, respectively, for the degradation of polyubiquitinated proteins. Moreover, using models of cellular aging, we find that a switch from BAG1 to BAG3 determines that aged cells use more intensively the macroautophagic system for turnover of polyubiquitinated proteins. This increased macroautophagic flux is regulated by BAG3 in concert with the ubiquitin-binding protein p62/SQSTM1. The BAG3/BAG1 ratio is also elevated in neurons during aging of the rodent brain, where, consistent with a higher macroautophagy activity, we find increased levels of the autophagosomal marker LC3-II as well as a higher cathepsin activity. We conclude that the BAG3-mediated recruitment of the macroautophagy pathway is an important adaptation of the protein quality control system to maintain protein homeostasis in the presence of an enhanced pro-oxidant and aggregation-prone milieu characteristic of aging

A homozygous mutation in the TUB gene associated with retinal dystrophy and obesity.

Inherited retinal dystrophies are a major cause of childhood blindness. Here, we describe the identification of a homozygous frameshift mutation (c.1194_1195delAG, p.Arg398Serfs*9) in TUB in a child from a consanguineous UK Caucasian family investigated using autozygosity mapping and whole-exome sequencing. The proband presented with obesity, night blindness, decreased visual acuity, and electrophysiological features of a rod cone dystrophy. The mutation was also found in two of the proband's siblings with retinal dystrophy and resulted in mislocalization of the truncated protein. In contrast to known forms of retinal dystrophy, including those caused by mutations in the tubby-like protein TULP-1, loss of function of TUB in the proband and two affected family members was associated with early-onset obesity, consistent with an additional role for TUB in energy homeostasis.Contract grant sponsors: Wellcome Trust (077016/Z/05/Z, 098497/Z/12/Z, 096106/Z/11/Z); National Institute for Health Research (Moorfields Biomedical Research Centre and Cambridge Biomedical Research Centre); Fight for Sight; Foundation Fighting Blindness (USA); the Rosetrees Trust; European Community (FP7/2009/241955 “SYSCILIA”); The FAUN Foundation (Germany).This is the final published version. It first appeared at http://onlinelibrary.wiley.com/doi/10.1002/humu.22482/abstract