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Store operated Ca2+ entry (SOCE) is a ubiquitous signalling module with established roles in the immune system, secretion and muscle development. Recent evidence supports a complex role for SOCE in the nervous system. In this review we present an update of the current knowledge on SOCE function in the brain with a focus on its role as a regulator of brain activity and excitability [ABSTRACT FROM AUTHOR]

This document is a response to a study that questioned the results of a previous study on the effects of L-Type Ca2+ channel blockers on synthetic arterial myocytes. The authors of the response defend their conclusions and provide evidence to support their findings. They argue that the previous study did not replicate their key observations and that their conclusions are not incorrect due to the fluorescence of amlodipine. They also present evidence of the activation of CRAC currents by amlodipine and other Ca2+ channel blockers. The text also discusses a study by Bird et al. that challenges the findings of another study by Johnson et al. on the effects of L-type calcium channel blockers on store-operated calcium entry (SOCE) and heart failure. Johnson et al. argue that L-type calcium channel blockers can promote vascular remodeling through the activation of STIM proteins. Bird et al. dispute these findings and suggest that L-type calcium channel blockers are not effective in preventing heart failure. The text also addresses criticisms and responses from other researchers regarding the two studies. [Extracted from the article]

Background and Purpose: Senescent preadipocytes promote adipose tissue dysfunction by secreting pro‐inflammatory factors, although little is known about the mechanisms regulating their production. We investigated if up‐regulated purinoceptor function sensitizes senescent preadipocytes to cognate agonists and how such sensitization regulates inflammation. Experimental Approach: Etoposide was used to trigger senescence in 3T3‐L1 preadipocytes. CRISPR/Cas9 technology or pharmacology allowed studies of transcription factor function. Fura‐2 imaging was used for calcium measurements. Interleukin‐6 levels were quantified using quantitative PCR and ELISA. Specific agonists and antagonists supported studies of purinoceptor coupling to interleukin‐6 production. Experiments in MS1 VEGF angiosarcoma cells and adipose tissue samples from obese mice complemented preadipocyte experiments. Key Results: DNA damage‐induced senescence up‐regulated purinoceptor expression levels in preadipocytes and MS1 VEGF angiosarcoma cells. ATP‐evoked Ca2+ release was potentiated in senescent preadipocytes. ATP enhanced interleukin‐6 production, an effect mimicked by ADP but not UTP, in a calcium‐independent manner. Senescence‐associated up‐regulation and activation of the adenosine A3 receptor also enhanced interleukin‐6 production. However, nucleotide hydrolysis was not essential because exposure to ATPγS also enhanced interleukin‐6 secretion. Pharmacological experiments suggested coupling of P2X ion channels and P2Y12–P2Y13 receptors to downstream interleukin‐6 production. Interleukin‐6 signalling exacerbated inflammation during senescence and compromised adipogenesis. Conclusions and Implications: We report a previously uncharacterized link between cellular senescence and purinergic signalling in preadipocytes and endothelial cancer cells, raising the possibility that up‐regulated purinoceptors play key modulatory roles in senescence‐associated conditions like obesity and cancer. There is potential for exploitation of specific purinoceptor antagonists as therapeutics in inflammatory disorders. [ABSTRACT FROM AUTHOR]

Loss of function mutations in store‐operated Ca2+ entry (SOCE) are associated with severe paediatric disorders in humans, including combined immunodeficiency, anaemia, thrombocytopenia, anhidrosis and muscle hypotonia. Given its central role in immune cell activation, SOCE has been a therapeutic target for autoimmune and inflammatory diseases. Treatment for such chronic diseases would require prolonged SOCE inhibition. It is, however, unclear whether chronic SOCE inhibition is viable therapeutically. Here we address this issue using a novel genetic mouse model (SOCE hypomorph) with deficient SOCE, nuclear factor of activated T cells activation, and T cell cytokine production. SOCE hypomorph mice develop and reproduce normally and do not display muscle weakness or overt anhidrosis. They do, however, develop cardiovascular complications, including hypertension and tachycardia, which we show are due to increased sympathetic autonomic nervous system activity and not cardiac or vascular smooth muscle autonomous defects. These results assert that chronic SOCE inhibition is viable therapeutically if the cardiovascular complications can be managed effectively clinically. They further establish the SOCE hypomorph line as a genetic model to define the therapeutic window of SOCE inhibition and dissect toxicities associated with chronic SOCE inhibition in a tissue‐specific fashion. Key points: A floxed stromal interaction molecule 1 (STIM1) hypomorph mouse model was generated with significant reduction in Ca2+ influx through store‐operated Ca2+ entry (SOCE), resulting in defective nuclear translocation of nuclear factor of activated T cells, cytokine production and inflammatory response. The hypomorph mice are viable and fertile, with no overt defects.Decreased SOCE in the hypomorph mice is due to poor translocation of the mutant STIM1 to endoplasmic reticulum–plasma membrane contact sites resulting in fewer STIM1 puncta.Hypomorph mice have similar susceptibility to controls to develop diabetes but exhibit tachycardia and hypertension. The hypertension is not due to increased vascular smooth muscle contractility or vascular remodelling.The tachycardia is not due to heart‐specific defects but rather seems to be due to increased circulating catecholamines in the hypomorph.Therefore, long term SOCE inhibition is viable if the cardiovascular defects can be managed clinically. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2008.09.007 Byline: Wassim El-Jouni (a), Shirley Haun (a), Khaled Machaca (a)(b) Keywords: Plasma-membrane Ca.sup.2+ ATPase (PMCA); Calcium; Oocyte maturation; Endocytosis; Trafficking; Lipid-rafts; Xenopus laevis Abstract: A transient increase in intracellular Ca.sup.2+ is the universal signal for egg activation at fertilization. Eggs acquire the ability to mount the specialized fertilization-specific Ca.sup.2+ signal during oocyte maturation. The first Ca.sup.2+ transient following sperm entry in vertebrate eggs has a slow rising phase followed by a sustained plateau. The molecular determinants of the sustained plateau are poorly understood. We have recently shown that a critical determinant of Ca.sup.2+ signaling differentiation during oocyte maturation is internalization of the plasma membrane calcium ATPase (PMCA). PMCA internalization is representative of endocytosis of several integral membrane proteins during oocyte maturation, a requisite process for early embryogenesis. Here we investigate the mechanisms regulating PMCA internalization. To track PMCA trafficking in live cells we cloned a full-length cDNA of Xenopus PMCA1, and show that GFP-tagged PMCA traffics in a similar fashion to endogenous PMCA. Functional data show that MPF activation during oocyte maturation is required for full PMCA internalization. Pharmacological and co-localization studies argue that PMCA is internalized through a lipid raft endocytic pathway. Deletion analysis reveal a requirement for the N-terminal cytoplasmic domain for efficient internalization. Together these studies define the mechanistic requirements for PMCA internalization during oocyte maturation. Author Affiliation: (a) Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, AR, USA (b) Weill Cornell Medical College in Qatar, Qatar Foundation, Education City, Doha, Qatar Article History: Received 27 June 2008; Revised 14 August 2008; Accepted 8 September 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ydbio.2005.10.034 Byline: Wassim El-Jouni, Byungwoo Jang, Shirley Haun, Khaled Machaca Keywords: Oocyte maturation; Xenopus; Ca.sup.2+ signaling; IP.sub.3 receptor; Plasma membrane Ca.sup.2+ ATPase; Endocytosis Abbreviations: Ca.sup.2+.sub.cyt, cytoplasmic Ca.sup.2+; IP.sub.3, d-myo-inositol-1,4,5-trisphosphate; Caged-IP.sub.3, d-myo-inositol 1,4,5-trisphosphate, P4(5)-(1-(2-nitrophenyl)ethyl) ester; IP.sub.3R, IP.sub.3 receptor; GVBD, germinal vesicle breakdown; MPF, maturation promoting factor; SOCE, store operated Ca.sup.2+ entry; ER, endoplasmic reticulum; OG-1, Oregon Green BAPTA-1; PMCA, plasma membrane Ca.sup.2+-ATPase; SERCA, sarco-endoplasmic reticulum Ca.sup.2+-ATPase; EGTA, ethylene glycol-bis(b-aminoethyl ether)-N,N,N',N'-tetraacetic acid; BAPTA, 1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; NP-EGTA, o-nitrophenyl EGTA; PIP2, phosphatidylinositol-4,5-bisphosphate Abstract: Ca.sup.2+ is the universal signal for egg activation at fertilization in all sexually reproducing species. The Ca.sup.2+ signal at fertilization is necessary for egg activation and exhibits specialized spatial and temporal dynamics. Eggs acquire the ability to produce the fertilization-specific Ca.sup.2+ signal during oocyte maturation. However, the mechanisms regulating Ca.sup.2+ signaling differentiation during oocyte maturation remain largely unknown. At fertilization, Xenopus eggs produce a cytoplasmic Ca.sup.2+ (Ca.sup.2+.sub.cyt) rise that lasts for several minutes, and is required for egg activation. Here, we show that during oocyte maturation Ca.sup.2+ transport effectors are tightly modulated. The plasma membrane Ca.sup.2+ ATPase (PMCA) is completely internalized during maturation, and is therefore unable to extrude Ca.sup.2+ out of the cell. Furthermore, IP.sub.3-dependent Ca.sup.2+ release is required for the sustained Ca.sup.2+.sub.cyt rise in eggs, showing that Ca.sup.2+ that is pumped into the ER leaks back out through IP.sub.3 receptors. This apparent futile cycle allows eggs to maintain elevated cytoplasmic Ca.sup.2+ despite the limited available Ca.sup.2+ in intracellular stores. Therefore, Ca.sup.2+ signaling differentiates in a highly orchestrated fashion during Xenopus oocyte maturation endowing the egg with the capacity to produce a sustained Ca.sup.2+.sub.cyt transient at fertilization, which defines the egg's competence to activate and initiate embryonic development. Author Affiliation: Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, 4301 West Markham St. Slot 505, Little Rock, AR 72205, USA Article History: Received 29 July 2005; Revised 6 October 2005; Accepted 26 October 2005

Transport effectors of Ca(2+) are tightly modulated during Xenopus oocycte maturation; processes are described for maintaining elevated cytoplasmic Ca(2+) necessary for initiating embryonic development.

Author(s): Courtney Wilkins [1]; Ryan Dishongh [1]; Steve C. Moore [1, 3]; Michael A. Whitt [4]; Marie Chow (corresponding author) [1]; Khaled Machaca (corresponding author) [2] RNA interference (RNAi) is [...]

The universal signal for egg activation at fertilization is a rise in cytoplasmic [Ca.sup.2+] with defined spatial and temporal kinetics. Mammalian and amphibian eggs acquire the ability to produce such [Ca.sup.2+] signals during a maturation period that precedes fertilization and encompasses resumption of meiosis and progression to metaphase II. In Xenopus, immature oocytes produce fast, saltatory [Ca.sup.2+] waves that can be oscillatory in nature in response to I[P.sub.3]. In contrast, mature eggs produce a single continuous, sweeping [Ca.sup.2+] wave in response to I[P.sub.3] or sperm fusion. The mechanisms mediating the differentiation of [Ca.sup.2+] signaling during oocyte maturation are not well understood. Here, I characterized elementary [Ca.sup.2+] release events ([Ca.sup.2+] puffs) in oocytes and eggs and show that the sensitivity of I[P.sub.3]-dependent [Ca.sup.2+] release is greatly enhanced during oocyte maturation. Furthermore, [Ca.sup.2+] puffs in eggs have a larger spatial fingerprint, yet are short lived compared to oocyte puffs. Most interestingly, [Ca.sup.2+] puffs cluster during oocyte maturation resulting in a continuum of [Ca.sup.2+] release sites over space in eggs. These changes in the spatial distribution of elementary [Ca.sup.2+] release events during oocyte maturation explain the continuous nature and slower speed of the fertilization [Ca.sup.2+] wave. Keywords: Oocyte maturation; Xenopus; [Ca.sup.2+] signaling; IP3-dependent [Ca.sup.2+] release; [Ca.sup.2+] puffs; [Ca.sup.2+] waves: Fertilization; Elementary [Ca.sup.2+] release; [Ca.sup.2+] imaging; Meiosis

[Ca.sup.2+] is a ubiquitous intracellular messenger that is important for cell cycle progression. Genetic and biochemical evidence support a role for [Ca.sup.2+] in mitosis. In contrast, there has been a long-standing debate as to whether [Ca.sup.2+] signals are required for oocyte meiosis. Here, we show that cytoplasmic [Ca.sup.2+] ([Ca.sup.2+.sub.cyt]) plays a dual role during Xenopus oocyte maturation. [Ca.sup.2+] signals are dispensable for meiosis entry (germinal vesicle breakdown and chromosome condensation), but are required for the completion of meiosis I. Interestingly, in the absence of [Ca.sup.2+.sub.cyt] signals oocytes enter meiosis more rapidly due to faster activation of the MAPK-maturation promoting factor (MPF) kinase cascade. This [Ca.sup.2+]-dependent negative regulation of the cell cycle machinery (MAPK-MPF cascade) is due to [Ca.sup.2+.sub.cyt] acting downstream of protein kinase A but upstream of Mos (a MAPK kinase kinase). Therefore, high [Ca.sup.2+.sub.cyt] delays meiosis entry by negatively regulating the initiation of the MAPK-MPF cascade. These results show that [Ca.sup.2+] modulates both the cell cycle machinery and nuclear maturation during meiosis.