Mitochondrial involvement in cell death: release of pro-apoptotic proteins

In addition to the role of the mitochondria in energy metabolism, these organelles play a key role in cell death signaling. In particular, mitochondrial alterations, such as stimulation of reactive oxygen species (ROS) formation, decreased ATP synthesis, loss of membrane potential and the release of pro-apoptotic proteins from the mitochondrial intermembrane space (IMS), have been shown to be involved in, and often responsible for, various manifestations of cell death. Among the pro-apoptotic proteins to be released are cytochrome c and Apoptosis-Inducing Factor (AIF). While cytochrome c initiates caspase-dependent cell death, AIF leads to caspase-independent cell death. The release of pro-apoptotic proteins from the IMS is considered as a “point of no return” in apoptotic signaling, although the mechanisms regulating permeabilization of the outer mitochondrial membrane remain controversial. Two main mechanisms have been elaborated including the induction of mitochondrial permeability transition (MPT) and selective pore formation by the Bcl-2 (B-cell lymphoma 2) family proteins, Bax and Bak. Although, distinct cell death pathways can be triggered by various signals, they often merge at a common regulator of this multistep process. Currently, it is widely accepted that the mitochondria serve as such a regulator. Therefore, the main goal of this project was to investigate the involvement of mitochondria in cell death. While cytosolic Bax is known to target the mitochondria to induce mitochondrial outer membrane permeabilization (MOMP) during apoptosis, less is known about its mitochondria-specific target. We addressed this issue and could show that a functional translocase of the outer mitochondrial membrane (TOM complex) is required for Bax to release cytochrome c from the mitochondria. Previous work in our group has established that AIF-mediated, and caspase- independent apoptosis is the main cell death mechanism in non-small cell lung carcinomas treated with anticancer drugs. However, the molecular mechanisms underlying AIF release remained obscure. We addressed this issue and could show that Ca2+ was imported into cells upon treatment of cells with protein kinase C (PKC) inhibitors. The imported Ca2+ had two critical functions; a) the activation of a mitochondrial calpain that could cleave AIF, a step essential for its release and b) to stimulate mitochondrial ROS production. This, in turn, led to a selective posttranslational modification, carbonylation of AIF, which significantly sensitized AIF to calpain-mediated processing. Recently, we were also able to define the pathway by which Ca2+ entered cells exposed to the PKC inhibitors. We found that the hyperpolarization-activated cyclic nucleotide-gated channel 2 (HCN2) mediated a sustained Ca2+ import, which was triggered by dephosphorylation of a critical residue within the conserved C-terminus of the channel in cells treated with PKC-inhibitors. Our findings reveal a novel role for the HCN2 channel in cell death signaling and uncover a new potential therapeutic drug target

Access to archives: democracy and transparency

Referat, kroz nekoliko tema - međunarodni programi rada, povijest i demokracija, aktivna zaštita kao sredstvo demokracije i povijesnog istraživanja - govori o dostupnosti arhivskog gradiva, demokraciji i transparentnosti. U demokratskom sustavu svatko ima pravo na vlastitu kulturnu baštinu. U političkoj raspravi koristimo prava različitih vrsta, označena kao civilna ili demokratska prava. Najpoznatiji tekst o pravima je UN-ova Deklaracija o ljudskim pravima. Prvih 21 pravo su u klasičnoj liberalnoj tradiciji - pravo na slobodu, pravo glasa, pravna sigurnost, integritet, sloboda misli i sloboda tiska. Deklaracija sadrži i druga prava, kao što su socijalna sigurnost, pravo na adekvatnu odjeću, obrazovanje, pravo na rad, pravo na uživanje umjetnosti i dostignuća znanosti. Među pravima koja se odnose na arhive, kao što su pravo na kulturnu baštinu i pravo na obrazovanje, moramo dati prioritet predmetima koji odgovaraju neposredno na osnovno pravo na slobodu iz Deklaracije. To može biti samo dostupnost informacija. UNESCO je tradicionalni partner arhiva. Od prije pola godine nastojanja su usmjerena na sjedinjenje dva UNESCO-va informacijska programa, Općeg Informacijskog programa (PGI) i Međuvladinog informacijskog programa (IIP). Oba se odnose na arhive. Nacrt programa izražava neke osnovne vrijednosti i pretpostavke, koje su povezane s demokratskim aspektima arhiva. U 1990-im arhivi su dobili važnog partnera u Vijeću Evrope. Svi poznajemo rad na nacrtu Preporuke Vijeća Evrope o dostupnosti arhivskog gradiva i rezoluciji CITRE iz Edinburgha 1997. godine i Evropskog sastanka arhiva u Bernu 1998, koji izražavaju interes arhivske zajednice za usvajanjem te Preporuke. Proces Evropske unije pokrenut 1996. godine doveo je do objavljivanja tzv. Zelene knjige o javnom sektoru informiranja u informatičkom društvu. Ona se bavi dostupnošću informacija s operativne točke gledišta. Knjiga posvećuje pažnju pitanju autorskog prava, ali samo sa stajališta ekonomskog interesa. Zelena knjiga također raspravlja o pitanju privatnosti. Zelenu su knjigu kritizirali arhivi na koje se ona odnosila i zbog pridavanja premale pažnje građanskim pravima i slobodi informacija. Strateški plan i Etički kodeks Međunarodnog arhivskog vijeća, koji su usvojeni 1996. godine, veoma su konkretni Tijekom povijesti, oni koji su imali moć, učinili su što su mogli kako bi kontrolirali povijest. Najočitiji je pokušaj iskrivljavanja povijesti iz sebičnih razloga zauzeo svoje mjesto u totalitarnim državama koje su uvijek postojale, a postoje još i danas u različitim dijelovima svijeta. Moć nad informacijama od bitnog je značaja za režime te vrste. Iskrivljavanje povijesti nužna je komponenta strategije opstanka režima. Nacionalni arhivi igraju različitu i važnu ulogu u društvima novih nezavisnih država, kako po svom sadržaju, tako i kao jasna potvrda važnosti demokratskog socijalnog poretka, s gradivom dostupnim za istraživanje javnosti. Njihova uloga je naročito značajna kada dolazi do pristupa informacijama nakon dugog vremenskog razdoblja, npr. između generacija i kada se izlaže ono što se dogodilo tijekom razdoblja ranije zaodjenutog velom tajnosti. Naročito je važno da ta memorija bude dostupna za sve odnosno da informacije koje se čuvaju u arhivima budu dostupne svakome. Naša kulturna baština ne može se čuvati u cijelosti, zbog činjenice što neki događaji nisu nikad dokumentirani, pa informacija nestaje sa sjećanjem osoba uključenih u te događaje. Kulturna baština nestaje zbog činjenice da važno gradivo nije namijenjeno za trajno čuvanje, zbog činjenice da se važne informacije pohranjuju na medijima koji nisu odgovarajući za trajno čuvanje ili se čuvaju u lošim kimatskim uvjetima, zbog činjenice da neke informacije ne mogu biti dostupne zbog neodgovarajućih obavijesnih ili praktičnih pomagala, te kao rezultat vrednovanja u arhivima. Postupak vrednovanja kontroverzno je pitanje. Drugo pitanje proizlazi iz rasprave o privatnosti. Ukoliko se složimo da se kontekstualna vrijednost ne izvodi samo iz načina na koji je gradivo nastalo, već također i iz načina na koji je ono čuvano ili sređeno, moramo znati više o promišljenom uništavanju gradiva. Jedan od aspekata je dostupnost arhivskog gradiva koje je premješteno s njegovog izvornog mjesta. Od ranog 17. stoljeća imamo iskustvo s mirovnim ugovorima u koje su uključene odluke o dijeljenju arhivskoga gradiva koje je premješteno tijekom rata ili na koje utječu nove granice između država. Razvijena je sofisticirana teorija kako bi se načinila razlika između provenijencije, pertinencije i funkcionalne vrijednosti. Kulturna baština u velikoj je opasnosti zbog ekonomskih, političkih ili tehničkih rizika. Ali taj se trend može zaustaviti ukoliko se uloži dodatni napor: zakonodavstvo mora biti prilagođeno i primijenjeno tako, da ne bude u suprotnosti sa svrhom zaštite; moramo poticati povijesnu svijest i razumijevanje za korist od zaštite gradiva; moramo razviti metode pohrane gradiva, medije i materijale, promovirati standardizaciju kvalitete i vještina; moramo obostrano razmjenjivati iskustva s drugim zemljama dvostranim ugovorima ili još bolje koristeći kredibilitet i ekspertizu Međunarodnog arhivskog vijeća; trebamo uvidjeti da su arhivi također na programu važnih međunarodnih partnera kao što su UNESCO, Vijeće Evrope i Evropska unija; moramo učiniti svakoga svjesnim činjenice, da je dobar arhiv obilježje zdrave demokracije

Beilagen zur Geschichte der Erfindungen, herausgegeben von J. E. Norberg wirklicher Etatsrath und Marine-Ingenieur, Mitglied der Schwedisch-Königlichen Wissenschafts, Mahler- und Bildhauer-Academien, der Russisch-Kaiserlichen und den Finländischen Oeconomischen Gesellschaften, der Patriotischen Gesellschaft zu Stockholm und der Physiographischen zu Lund. Erstes Heft. Reval, gedruckt bei J. H. Gressel

https://www.ester.ee/record=b1636095*es

Critical role for hyperpolarization-activated cyclic nucleotide-gated channel 2 in the AIF-mediated apoptosis

This study establishes HCN2 channels as physiological relevant ‘calcium gates' that mediate apoptosis-inducing factor-dependent cell death in cancer and primary neuronal cells

Four-channel WDM transmitter with heterogeneously integrated III-V/Si photonics and low power 32 nm CMOS drivers

Artículo científicoWe experimentally demonstrate a novel four-channel wavelength division multiplexing transmitter operating at 1.3 μm wavelength employing heterogeneously integrated III-V/Si photonic circuit copackaged with low-power 32-nm SOI CMOS driver integrated circuits (ICs). Error-free operation (BER < 10−12 ) has been achieved across all four channels for back-to-back, 2 and 10 km single-mode fiber transmission at 25 Gb/s per each channel, targeting intra- and inter-datacenter interconnect applications. Power consumption as low as 19.2 mW for four CMOS driver ICs has been recorded, which yields 0.19 pJ/bit energy efficiency

Pituitary Gonadotropin Gene Expression During Induced Onset of Postsmolt Maturation in Male Atlantic Salmon: In Vivo and Tissue Culture Studies

Precocious male maturation causes reduced welfare and increased production costs in Atlantic salmon (Salmo salar) aquaculture. The pituitary produces and releases follicle-stimulating hormone (Fsh), the gonadotropin triggering puberty in male salmonids. However, little is known about how Fsh production is regulated in Atlantic salmon. We examined, in vivo and ex vivo, transcriptional changes of gonadotropin-related genes accompanying the initial steps of testis maturation, in pituitaries of males exposed to photoperiod and temperature conditions promoting maturation (constant light and 16°C). Pituitary fshb, lhb and gnrhr2bba transcripts increased in vivo in maturing males (gonado-somatic index > 0.1%). RNA sequencing (RNAseq) analysis using pituitaries from genetically similar males carrying the same genetic predisposition to mature, but differing by responding or not responding to stimulatory environmental conditions, revealed 144 differentially expressed genes, ~2/3rds being up-regulated in responders, including fshb and other pituitary hormones, steroid-related and other puberty-associated transcripts. Functional enrichment analyses confirmed gene involvement in hormone/steroid production and gonad development. In ex vivo studies, whole pituitaries were exposed to a selection of hormones and growth factors. Gonadotropin-releasing hormone (Gnrh), 17β-estradiol (E2) and 11-ketotestosterone (11-KT) up-regulated gnrhr2bba and lhb, while fshb was up-regulated by Gnrh but down-regulated by 11-KT in pituitaries from immature males. Also pituitaries from maturing males responded to Gnrh and sex steroids by increased gnrhr2bba and lhb transcript levels, but fshb expression remained unchanged. Growth factors (inhibin A, activin A and insulin-like growth factor 1) did not change gnrhr2bba, lhb or fshb transcript levels in pituitaries either from immature or maturing males. Additional pituitary ex vivo studies on candidates identified by RNAseq showed that these transcripts were preferentially regulated by Gnrh and sex steroids, but not by growth factors, and that Gnrh/sex steroids were less effective when incubating pituitaries from maturing males. Our results suggest that a yet to be characterized mechanism up-regulating fshb expression in the salmon pituitary is activated in response to stimulatory environmental conditions prior to morphological signs of testis maturation, and that the transcriptional program associated with this mechanism becomes unresponsive or less responsive to most stimulators ex vivo once males had entered pubertal developmental in vivo.publishedVersio

An Integrated-Photonics Optical-Frequency Synthesizer

Integrated-photonics microchips now enable a range of advanced functionalities for high-coherence applications such as data transmission, highly optimized physical sensors, and harnessing quantum states, but with cost, efficiency, and portability much beyond tabletop experiments. Through high-volume semiconductor processing built around advanced materials there exists an opportunity for integrated devices to impact applications cutting across disciplines of basic science and technology. Here we show how to synthesize the absolute frequency of a lightwave signal, using integrated photonics to implement lasers, system interconnects, and nonlinear frequency comb generation. The laser frequency output of our synthesizer is programmed by a microwave clock across 4 THz near 1550 nm with 1 Hz resolution and traceability to the SI second. This is accomplished with a heterogeneously integrated III/V-Si tunable laser, which is guided by dual dissipative-Kerr-soliton frequency combs fabricated on silicon chips. Through out-of-loop measurements of the phase-coherent, microwave-to-optical link, we verify that the fractional-frequency instability of the integrated photonics synthesizer matches the $7.0*10^{-13}$ reference-clock instability for a 1 second acquisition, and constrain any synthesis error to $7.7*10^{-15}$ while stepping the synthesizer across the telecommunication C band. Any application of an optical frequency source would be enabled by the precision optical synthesis presented here. Building on the ubiquitous capability in the microwave domain, our results demonstrate a first path to synthesis with integrated photonics, leveraging low-cost, low-power, and compact features that will be critical for its widespread use.Comment: 10 pages, 6 figure

Full production cycle performance of gene-edited, sterile Atlantic salmon - growth, smoltification, welfare indicators and fillet composition

Using germ cell-free (GCF), sterile, dnd-knockout salmon for farming could solve the problems associated with precocious maturation and genetic introgression of farmed breeds into wild populations. However, prior to using GCF fish in the salmon farming industry, it is crucial to understand if, or how, the GCF phenotype differs from wild type (WT) counterparts in terms of growth and welfare. To characterize the GCF phenotype throughout a production cycle, we reared GCF and WT salmon in indoor common garden tanks for 3 years, until harvest size. Regarding body size, smoltification markers (mRNA levels of gill Na+/K+-ATPase [NKA] subunits), plasma stress indicators (pH, glucose, sodium, chloride, calcium), relative heart size, prevalence of vertebra deformities and fillet proximate composition, GCF fish could not be distinguished from WTs. Transient differences were detected in plasma concentrations of lactate and osmolality, and only a few genes were differentially expressed in WT and GCF transcriptomes of muscle and pituitary. At harvest, fillets from GCF and WT salmon contained the same amount of omega-3 fatty acids, however the relative content of omega-3 fatty acids was higher in GCF compared to WT males. Towards harvest size, body growth rate, condition factor and relative liver size were significantly higher in WT than in GCF fish, probably relating to initiation of puberty in WTs. Since GCF salmon never become sexually mature, it is possible to postpone the time of harvest to exploit the growth potential uninhibited by sexual maturation. In conclusion, GCF salmon performed to a large extent similarly to their WT counterparts but had the clear advantage of never maturing.publishedVersio

Degradation of HK2 by chaperone-mediated autophagy promotes metabolic catastrophe and cell death

Hexokinase II (HK2), a key enzyme involved in glucose metabolism, is regulated by growth factor signaling and is required for initiation and maintenance of tumors. Here we show that metabolic stress triggered by perturbation of receptor tyrosine kinase FLT3 in non–acute myeloid leukemia cells sensitizes cancer cells to autophagy inhibition and leads to excessive activation of chaperone-mediated autophagy (CMA). Our data demonstrate that FLT3 is an important sensor of cellular nutritional state and elucidate the role and molecular mechanism of CMA in metabolic regulation and mediating cancer cell death. Importantly, our proteome analysis revealed that HK2 is a CMA substrate and that its degradation by CMA is regulated by glucose availability. We reveal a new mechanism by which excessive activation of CMA may be exploited pharmacologically to eliminate cancer cells by inhibiting both FLT3 and autophagy. Our study delineates a novel pharmacological strategy to promote the degradation of HK2 in cancer cells