Die Rolle von Serin-Threonin-Kinasen für epitheliale Transportvorgänge

The phosphoinositide dependent kinase PDK1 activates the SGK isoforms SGK1, SGK2 and SGK3 and protein kinase B isoforms which in turn are known to stimulate a variety of sodium coupled transporters, such as the renal and intestinal Na+-dependent glucose transporter SGLT1. SGK1 is known to be up-regulated by mineralocorticoids and to enhance ENaC activity in several expression systems. Moreover, the amiloride-sensitive transepithelial potential difference in collecting duct is lower in gene-targeted mice lacking SGK1 (sgk1-/-) than in their wild type littermates (sgk1+/+). Accordingly, the ability of sgk1-/- mice to decrease urinary sodium output during salt depletion is impaired. ENaC activity and thus transepithelial potential difference in the colon are similarly influenced by mineralocorticoids. The first aim of the present study was to explore the role of PDK1 in in electrogenic glucose and amino-acid transport in small intestine and proximal renal tubules As mice completely lacking functional PDK1 are not viable, mice expressing 10-25% of PDK1 (pdk1hm) were compared to their wild type littermates (pdk1wt). Body weight was significantly smaller in pdk1hm than in pdk1wt mice. Despite lower body weight of pdk1hm mice, food and water intake were similar in pdk1hm and pdk1wt mice. Ussing chamber experiments showed that electrogenic transport of glucose as well as phenylalanine, cysteine, glutamine, proline, leucine and tryptophan was significantly smaller in jejunum of pdk1hm mice compared to pdk1wt mice. Similarly, proximal tubular electrogenic glucose transport as well as phenylalanine, glutamine and proline transport in isolated perfused renal tubule segments was decreased. Intraperitoneal injection of 3 g/kg bw glucose resulted in a similar increase of plasma glucose concentration in pdk1hm and in pdk1wt mice but led to a higher increase of urinary glucose excretion in pdk1hm mice. The urinary excretion of proline, valine, guanidinoacetate, methionine, phenylalanine, citrulline, glutamine/glutamate and tryptophan was significantly larger in pdk1hm than in pdk1wt mice. According to immunoblotting of brush border membrane proteins prepared from kidney, expression of the Na+-dependent neutral amino acid transporter B0AT1 (SLC6A19), the glutamate transporter EAAC1/EAAT3 (SLC1A1) and the transporter for cationic amino acids and cystine b0,+AT (SLC7A9) was decreased but the Na+/proline cotransporter SIT (SLC6A20) was increased in pdk1hm mice. In conclusion, reduction of functional PDK1 leads to impairment of intestinal absorption and renal reabsorption of amino acids of electrogenic intestinal glucose absorption and renal glucose reabsorption. The combined intestinal and renal loss of amino acids may contribute to the growth defect of PDK1 deficient mice. The experiments disclose a novel element of glucose transport regulation in kidney and small intestine. The next step was to look at the transepithelial potential (Vte) and the apparent amiloride-sensitive equivalent short circuit current (Iamil) in colon from sgk1-/- and sgk1+/+ mice. Both Vte and Iamil were significantly (p<0.05) higher in untreated sgk1-/- than in untreated sgk1+/+ mice under control diet. A 7 day exposure to low salt diet increased Vte and Iamil in both genotypes but did not abrogate the differences of Vte and Iamil between sgk1-/- and sgk1+/+ mice. Plasma aldosterone levels were significantly higher in sgk1-/- than in sgk1+/+ mice both under control conditions and under low salt diet. Treatment with dexamethasone (10µg/g BW) or with DOCA (1.5mg per day) significantly increased Vte and Iamil in sgk1+/+ mice but not in sgk1-/- mice. Under treatment with dexamethasone or DOCA Vte and Iamil were similar in sgk1-/- and sgk1+/+ mice. In conclusion, lack of SGK1 does not disrupt colonic ENaC activity and its regulation by salt depletion. Finally the functional significance of SGK3-dependent regulation of intestinal transport were studied. .Xenopus oocyte coexpression experiments revealed the capacity of SGK3 to up-regulate a variety of transport systems including the sodium-dependent glucose transporter SGLT1. To this end experiments were performed in gene targeted mice lacking functional sgk3 (sgk3-/-) and their wild type littermates (sgk3+/+). Oral food intake and fecal dry weight were significantly larger in sgk3-/- than in sgk3+/+mice. Glucose-induced current (Ig) in Ussing chamber as a measure of Na+ coupled glucose transport was significantly smaller in sgk3-/- than in sgk3+/+mouse jejunal segments. Fasting plasma glucose concentrations were significantly lower in sgk3-/- than in sgk3+/+mice. Intestinal electrogenic transport of phenylalanine, cysteine, glutamine and proline were not significantly different between sgk3-/- and sgk3+/+ mice. In conclusion, SGK3 is required for adequate intestinal Na+ coupled glucose transport and impaired glucose absorption may contribute to delayed growth and decreased plasma glucose concentrations of SGK3 deficient mice. The hypoglycemia might lead to enhanced food intake to compensate for impaired intestinal absorption.Die phosphoinositid-abhängige Kinase 1 (PDK1) aktiviert die SGK-Isoformen SGK1, SGK2 und SGK3 sowie die Isoformen der Proteinkinase B, die eine Vielzahl von Natrium-gekoppelten Transportern stimulieren wie z.B. den renalen und intestinalen glucose-Transporter SGLT1. SGK1 wird durch Mineralokortikoide hochreguliert und stimuliert die Aktivität des epithelialen Natrium-Kanals ENaC in verschiedenen Expressionssystemen. In SGK1 defizienten Mäusen (sgk1-/-) ist die amilorid-hemmbare transepitheliale Potentialdifferenz niedriger als in Wildtyp-Mäusen, unter Niedrigsalz-Diät ist die Fähigkeit zur Na-Konservierung in den sgk1-/- Mäusen eingeschränkt. Die ENaC-Aktivität im Kolon ist ähnlich wie in der Niere mineralokortikoid-abhängig. Das Ziel der ersten Studie war es, den Einfluss der PDK1 am elektrogenen Glukose- und Aminosäurentransport im Dünndarm und im proximalen Tubulus zu untersuchen. Da Mäuse mit vollständigem PDK1-Verlust nicht lebensfähig sind, wurden PDK1-hypomorphe Mäuse (pdk1hm) mit einer PDK1-Restaktivität von 10-25% untersucht. Das Körpergewicht der PDK1-hypomorphen Mäuse war signifikant geringer als dasjenige der Wildtyp-Tiere, die Futter- und Flüssigkeitsaufnahme waren jedoch ähnlich hoch. Ussing-Kammer-Experimente zeigten einen reduzierten elektrogenen Transport für Glukose sowie für die Aminosäuren Phenylalanin, Cystein, Glutamin, Prolin, Leucin und Tryptophan in pdk1hm -Mäusen verglichen mit pdk1wt Mäusen. Analog dazu war der elektrogene Transport im isolierten proximalen Tubulus für Glucose sowie für Phenylalanin, Glutamin und Prolin vermindert. Unter intraperitonealer Beladung mit 3 g/kg Glucose kam es zu einer Glukosurie in pdk1hm -Mäusen, trotz ähnlich hoher Glukose-Spiegel wie in Wildtyp-Mäusen. Die Urinausscheidung von Prolin, Valin, Guanidinoacetat, Methionin, Phenylalanin, Citrullin, Glutamine/Glutamat und Tryptophan war in pdk1hm -Mäusen signifikant höher als in Widltyp-Mäusen. Im Western Blot von renalen Bürstensaum-Membranen von pdk1hm Mäusen war die Expression der Na+-abhängigen neutralen Aminosäuren-transporter B0AT1 (SLC6A19), des Glutamat-Transporters EAAC1/EAAT3 (SLC1A1) sowie des Transporter für kationische Aminosäuren und Cystin b0,+AT (SLC7A9) erniedrigt, die Expression des Na+-Prolin Cotransporters SIT (SLC6A20) erhöht. Zusammenfassend konnte gezeigt werden, dass eine Reduktion der PDK1 zu einer verminderten intestinalen Absorption sowie renalen Reabsorption von Glukose und Aminosäuren führte, was auf einen bisher nicht bekannten Regulationsweg hinweist. Der kombinierte intestinale und renale Verlust von Aminosäuren und Glukose könnte zum Minderwuchs der PDK1 hypomorphen Mäuse beitragen. In weiteren Untersuchungen wurde die transepitheliale Potentialdifferenz (Vte) und der amilorid-hemmbare Kurzschluss-Strom (Iamil) im Kolon von SGK1 defizienten (sgk1-/-) und Wildtyp-Mäusen untersucht. Sowohl Vte und Iamil waren in unbehandelten sgk1-/--Mäusen unter Kontrolldiät signifikant höher als in sgk1+/+ Mäusen. Eine 7-tägige Behandlung mit einer Niedrigsalz-Diät erhöhte Vte und Iamil in beiden Genotypen, konnte den Unterschied in Vte und Iamil zwischen sgk1-/-- und Wildtyp-Mäusen jedoch nicht aufheben. Plasma-Aldosteron-Spiegel waren in sgk1-/- -Mäusen sowohl unter Kontroll- wie Niedrigsalz-Diät signifikant höher. Behandlung mit Dexamethason (10µg/g) oder mit DOCA (1.5mg/ die) erhöhte Vte und Iamil nur in Wildtyp-Mäusen, jedoch nicht in sgk1-/- Mäusen. Unter Behandlung mit Dexamethason oder DOCA waren sowohl Vte als auch Iamil in sgk1-/- und Wildtyp-Mäusen ähnlich hoch. Die Ergebnisse zeigen zusammengenommen, dass ein Fehlen der SGK1 nicht die Aktivität und Regulation des ENaCs im Kolon unterbricht. Zuletzt wurde die funktionelle Bedeutung der SGK3 in der Regulation des intestinalen Transports untersucht. Zuvor hatten Experimente im Xenopus-Expressionssystem gezeigt, dass die SGK3 eine Vielzahl von Transportern beeinflussen kann, u.a. den Glucosetransporters SGLT1. In SGK3-defizienten Mäusen (sgk3-/-) zeigte sich verglichen mit Wildtyp-Mäusen eine höhere Futteraufnahme und ein höheres Stuhltrockengewicht. Die Glukose-induzierten Ströme (Iglc) waren im Jejunum signifikant geringer in sgk3-/- - Mäusen als in Wildtyp-Tieren. Der Nüchtern-Blutzucker war in sgk3-/- -Mäusen signifikant niedriger. Der intestinale elektrogene Transport von Phenylalanin, Cystein, Glutamin und Prolin ware hingegen zwischen sgk3-/- und Wildtyp-Mäusen nicht verschieden. Daher kann gefolgert warden, dass die SGK3 für die intestinale Na+-gekoppelte Glukoseaufnahme erforderlich ist und dass eine verminderte Glukoseaufnahme für die Wachstumsretardierung und die niedrigen Blutzuckerwerte verantwortlich sein könnte, was zu einer kompensatorischen Zunahme der Futteraufnahme führen könnte

MANAGEMENT DECISIONMAKING UNDER UNCERTAINITY CONDITIONS IN FINANCIAL SECTOR

Vendimmarrja është sigurisht detyra më e rëndësishme e një menaxheri dhe shumë shpesh është një detyrë e vështir. Domeni i modeleve të analizës së vendimmarrjes bie midis dy rasteve ekstreme. Kjo varet nga shkalla e njohurive që kemi për rezultatin e veprimeve tona. Probabiliteti është një instrument i përdorur për të matur gjasat e shfaqjes për një ngjarje. Kur probabiliteti përdoret për të shprehur pasigurinë, anën determinonte ka një probabiliteti (ose zero), ndërsa në fundin tjetër ka probabilitet të sheshtë (të gjithë po aq të mundshëm). Menaxhimi i rrezikut në përgjithësi përfshinë identifikimin, matjen, monitorimin dhe kontrollin e rrezikut financiar. Pavarësisht nga fakti se ekzistojnë një varg metodash për menaxhimin e riskut në sektorin bankar, raportohet se ky lloj të rrezikut që në vazhdimësi paraqet problem fondamentale. Në Kosovë nuk është plotësisht e qartë nëse është bërë ndonjë analizë e mirëfilltë për të diskutuar vendimet e rrezikut potencial financiare qoftë të sektorit bankar, qoftë të sektorëve tjerë që do të mund të gjenerojnë rrezik financiar bankar. Bazuar në këtë hipotezë, ky hulumtim ka arritur qëllimin të analizojë vendimet e menaxhimit të rrezikut në sektorin bankar në Kosovë së bashku me katër rastet e studimit me bankat botërore, ku edhe do të ofrojnë rekomandime të nevojshme për të avancuar këtë kategori të menaxhimit. Sintetizimi i vendimeve të konstatuar në menaxhimin e rrezikut në vend me disa nga rastet më të mira dhe rastet më kritike në regjion, dhe botë ka rezultuar në disa rekomandime të rëndësishme të cilat mund të shfrytëzohen nga menaxhimet i sektorit bankar si mjet mësimi, si mjet parandalimi të paraqitjes së rrezikut dhe si mjet përshpejtimi të njohurive në lëmine e menaxhimit të rrezikut. Ky hulumtim ofron një procedurë vendimmarrëse hap pas hapi për zgjidhjen e problemeve komplekse. Mirëpo për analizimin dhe prezantimin e rezultateve është shfrytëzuar Metoda e Analizës Multi-kritere e marrjes së vendimeve. Analiza Multi-kritere e marrjes së vendimeve (MCDA) është një nën-disiplinë e operacioneve të kërkimit që konsideron të hapura kriteret e shumta në mjediset e vendim-marrjes, pasi që në jetën tonë të përditshme ose në mjedise profesionale, ka zakonisht kritere të shumta kundërthënëse që duhet të vlerësohen në procesin e marrjes së vendimeve

The Mtr4 Ratchet Helix and Arch Domain both Function to Promote RNA Unwinding

Mtr4 is a conserved Ski2-like RNA helicase and a subunit of the TRAMP complex that activates exosomemiated 3-5 turnover in nuclear RNA surveillance and processing pathways. Prominent features of the Mtr4 structure include a four-domain ring-like helicase core and a large arch domain that spans the core. The ‘ratchet helix’ is positioned to interact with RNA substrates as they move through the helicase. However, the contribution of the ratchet helix in Mtr4 activity is poorly understood. Here we show that strict conservation along the ratchet helix is particularly extensive for Ski2-like RNA helicases compared to related helicases. Mutation of residues along the ratchet helix alters in vitro activity in Mtr4 and TRAMP and causes slow growth phenotypes in vivo. We also identify a residue on the ratchet helix that influences Mtr4 affinity for polyadenylated substrates. Previous work indicated that deletion of the arch domain has minimal effect on Mtr4 unwinding activity. We now show that combining the arch deletion with ratchet helix mutations abolishes helicase activity and produces a lethal in vivo phenotype. These studies demonstrate that the ratchet helix modulates helicase activity and suggest that the arch domain plays a previously unrecognized role in unwinding substrates

Modified Substrate Specificity of a Methyltransferase Domain by Protein Insertion Into an Adenylation Domain of the Bassianolide Synthetase

Background: Creating designer molecules using a combination of select domains from polyketide synthases and/or nonribosomal peptide synthetases (NRPS) continues to be a synthetic goal. However, an incomplete understanding of how protein-protein interactions and dynamics affect each of the domain functions stands as a major obstacle in the field. Of particular interest is understanding the basis for a class of methyltransferase domains (MT) that are found embedded within the adenylation domain (A) of fungal NRPS systems instead of in an end-to-end architecture. Results: The MT domain from bassianolide synthetase (BSLS) was removed and the truncated enzyme BSLS-ΔMT was recombinantly expressed. The biosynthesis of bassianolide was abolished and N-desmethylbassianolide was produced in low yields. Co-expression of BSLS-ΔMT with standalone MT did not recover bassianolide biosynthesis. In order to address the functional implications of the protein insertion, we characterized the N-methyltransferase activity of the MT domain as both the isolated domain (MTBSLS) and as part of the full NRPS megaenzyme. Surprisingly, the MTBSLS construct demonstrated a relaxed substrate specificity and preferentially methylated an amino acid (L-Phe-SNAC) that is rarely incorporated into the final product. By testing the preference of a series of MT constructs (BSLS, MTBSLS, cMT, XLcMT, and aMT) to L-Phe-SNAC and L-Leu-SNAC, we further showed that restricting and/or fixing the termini of the MTBSLS by crosslinking or embedding the MT within an A domain narrowed the substrate specificity of the methyltransferase toward L-Leu-SNAC, the preferred substrate for the BSLS megaenzyme. Conclusions: The embedding of MT into the A2 domain of BSLS is not required for the product assembly, but is critical for the overall yields of the final products. The substrate specificity of MT is significantly affected by the protein context within which it is present. While A domains are known to be responsible for selecting and activating the biosynthetic precursors for NRPS systems, our results suggest that embedding the MT acts as a secondary gatekeeper for the assembly line. This work thus provides new insights into the embedded MT domain in NRPSs, which will facilitate further engineering of this type of biosynthetic machinery to create structural diversity in natural products

Validation of cytoplasmic-to-nuclear ratio of survivin as an indicator of improved prognosis in breast cancer

<p>Abstract</p> <p>Background</p> <p>Conflicting data exist regarding the prognostic and predictive impact of survivin (BIRC5) in breast cancer. We previously reported survivin cytoplasmic-to-nuclear ratio (CNR) as an independent prognostic indicator in breast cancer. Here, we validate survivin CNR in a separate and extended cohort. Furthermore, we present new data suggesting that a low CNR may predict outcome in tamoxifen-treated patients.</p> <p>Methods</p> <p>Survin expression was assessed using immunhistochemistry on a breast cancer tissue microarray (TMA) containing 512 tumours. Whole slide digital images were captured using an Aperio XT scanner. Automated image analysis was used to identify tumour from stroma and then to quantify tumour-specific nuclear and cytoplasmic survivin. A decision tree model selected using a 10-fold cross-validation approach was used to identify prognostic subgroups based on nuclear and cytoplasmic survivin expression.</p> <p>Results</p> <p>Following optimisation of the staining procedure, it was possible to evaluate survivin protein expression in 70.1% (n = 359) of the 512 tumours represented on the TMA. Decision tree analysis predicted that nuclear, as opposed to cytoplasmic, survivin was the most important determinant of overall survival (OS) and breast cancer-specific survival (BCSS). The decision tree model confirmed CNR of 5 as the optimum threshold for survival analysis. Univariate analysis demonstrated an association between a high CNR (>5) and a prolonged BCSS (HR 0.49, 95% CI 0.29-0.81, p = 0.006). Multivariate analysis revealed a high CNR (>5) was an independent predictor of BCSS (HR 0.47, 95% CI 0.27-0.82, p = 0.008). An increased CNR was associated with ER positive (p = 0.045), low grade (p = 0.007), Ki-67 (p = 0.001) and Her2 (p = 0.026) negative tumours. Finally, a high CNR was an independent predictor of OS in tamoxifen-treated ER-positive patients (HR 0.44, 95% CI 0.23-0.87, p = 0.018).</p> <p>Conclusion</p> <p>Using the same threshold as our previous study, we have validated survivin CNR as a marker of good prognosis in breast cancer in a large independent cohort. These findings provide robust evidence of the importance of survivin CNR as a breast cancer biomarker, and its potential to predict outcome in tamoxifen-treated patients.</p

Tumour-specific HMG-CoAR is an independent predictor of recurrence free survival in epithelial ovarian cancer

<p>Abstract</p> <p>Background</p> <p>Our group previously reported that tumour-specific expression of the rate-limiting enzyme in the mevalonate pathway, 3-hydroxy-3-methylglutharyl-coenzyme A reductase (HMG-CoAR) is associated with more favourable tumour parameters and a good prognosis in breast cancer. In the present study, the prognostic value of HMG-CoAR expression was examined in tumours from a cohort of patients with primary epithelial ovarian cancer.</p> <p>Methods</p> <p>HMG-CoAR expression was assessed using immunohistochemistry (IHC) on tissue microarrays (TMA) consisting of 76 ovarian cancer cases, analysed using automated algorithms to develop a quantitative scoring model. Kaplan Meier analysis and Cox proportional hazards modelling were used to estimate the risk of recurrence free survival (RFS).</p> <p>Results</p> <p>Seventy-two tumours were suitable for analysis. Cytoplasmic HMG-CoAR expression was present in 65% (n = 46) of tumours. No relationship was seen between HMG-CoAR and age, histological subtype, grade, disease stage, estrogen receptor or Ki-67 status. Patients with tumours expressing HMG-CoAR had a significantly prolonged RFS (p = 0.012). Multivariate Cox regression analysis revealed that HMG-CoAR expression was an independent predictor of improved RFS (RR = 0.49, 95% CI (0.25-0.93); p = 0.03) when adjusted for established prognostic factors such as residual disease, tumour stage and grade.</p> <p>Conclusion</p> <p>HMG-CoAR expression is an independent predictor of prolonged RFS in primary ovarian cancer. As HMG-CoAR inhibitors, also known as statins, have demonstrated anti-neoplastic effects <it>in vitro</it>, further studies are required to evaluate HMG-CoAR expression as a surrogate marker of response to statin treatment, especially in conjunction with current chemotherapeutic regimens.</p

Fast automatic quantitative cell replication with fluorescent live cell imaging

Hoffmann N, Keck M, Neuweger H, et al. Combining peak- and chromatogram-based retention time alignment algorithms for multiple chromatography-mass spectrometry datasets. BMC Bioinformatics. 2012;13(1): 21.Background Modern analytical methods in biology and chemistry use separation techniques coupled to sensitive detectors, such as gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). These hyphenated methods provide high-dimensional data. Comparing such data manually to find corresponding signals is a laborious task, as each experiment usually consists of thousands of individual scans, each containing hundreds or even thousands of distinct signals. In order to allow for successful identification of metabolites or proteins within such data, especially in the context of metabolomics and proteomics, an accurate alignment and matching of corresponding features between two or more experiments is required. Such a matching algorithm should capture fluctuations in the chromatographic system which lead to non-linear distortions on the time axis, as well as systematic changes in recorded intensities. Many different algorithms for the retention time alignment of GC-MS and LC-MS data have been proposed and published, but all of them focus either on aligning previously extracted peak features or on aligning and comparing the complete raw data containing all available features. Results In this paper we introduce two algorithms for retention time alignment of multiple GC-MS datasets: multiple alignment by bidirectional best hits peak assignment and cluster extension (BIPACE) and center-star multiple alignment by pairwise partitioned dynamic time warping (CEMAPP-DTW). We show how the similarity-based peak group matching method BIPACE may be used for multiple alignment calculation individually and how it can be used as a preprocessing step for the pairwise alignments performed by CEMAPP-DTW. We evaluate the algorithms individually and in combination on a previously published small GC-MS dataset studying the Leishmania parasite and on a larger GC-MS dataset studying grains of wheat (Triticum aestivum). Conclusions We have shown that BIPACE achieves very high precision and recall and a very low number of false positive peak assignments on both evaluation datasets. CEMAPP-DTW finds a high number of true positives when executed on its own, but achieves even better results when BIPACE is used to constrain its search space. The source code of both algorithms is included in the OpenSource software framework Maltcms, which is available from http://maltcms.sf.net webcite. The evaluation scripts of the present study are available from the same source

Blunted apoptosis of erythrocytes in mice deficient in the heterotrimeric G-protein subunit Gαi2

Putative functions of the heterotrimeric G-protein subunit Gαi2-dependent signaling include ion channel regulation, cell differentiation, proliferation and apoptosis. Erythrocytes may, similar to apoptosis of nucleated cells, undergo eryptosis, characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine (PS) exposure. Eryptosis may be triggered by increased cytosolic Ca2+ activity and ceramide. In the present study, we show that Gαi2 is expressed in both murine and human erythrocytes and further examined the survival of erythrocytes drawn from Gαi2-deficient mice (Gαi2−/−) and corresponding wild-type mice (Gαi2+/+). Our data show that plasma erythropoietin levels, erythrocyte maturation markers, erythrocyte counts, hematocrit and hemoglobin concentration were similar in Gαi2−/− and Gαi2+/+ mice but the mean corpuscular volume was significantly larger in Gαi2−/− mice. Spontaneous PS exposure of circulating Gαi2−/− erythrocytes was significantly lower than that of circulating Gαi2+/+ erythrocytes. PS exposure was significantly lower in Gαi2−/− than in Gαi2+/+ erythrocytes following ex vivo exposure to hyperosmotic shock, bacterial sphingomyelinase or C6 ceramide. Erythrocyte Gαi2 deficiency further attenuated hyperosmotic shock-induced increase of cytosolic Ca2+ activity and cell shrinkage. Moreover, Gαi2−/− erythrocytes were more resistant to osmosensitive hemolysis as compared to Gαi2+/+ erythrocytes. In conclusion, Gαi2 deficiency in erythrocytes confers partial protection against suicidal cell death