Regulatory mechanisms controlling store-operated calcium entry.

Calcium influx through plasma membrane ion channels is crucial for many events in cellular physiology. Cell surface stimuli lead to the production of inositol 1,4,5-trisphosphate (IP), which binds to IP receptors (IPR) in the endoplasmic reticulum (ER) to release calcium pools from the ER lumen. This leads to the depletion of ER calcium pools, which has been termed store depletion.

Regulatory mechanisms controlling store-operated calcium entry.

Calcium influx through plasma membrane ion channels is crucial for many events in cellular physiology. Cell surface stimuli lead to the production of inositol 1,4,5-trisphosphate (IP), which binds to IP receptors (IPR) in the endoplasmic reticulum (ER) to release calcium pools from the ER lumen. This leads to the depletion of ER calcium pools, which has been termed store depletion.

Regulation of T cell function by protein S-acylation.

S-acylation, the reversible lipidation of free cysteine residues with long-chain fatty acids, is a highly dynamic post-translational protein modification that has recently emerged as an important regulator of the T cell function. The reversible nature of S-acylation sets this modification apart from other forms of protein lipidation and allows it to play a unique role in intracellular signal transduction. In recent years, a significant number of T cell proteins, including receptors, enzymes, ion channels, and adaptor proteins, were identified as S-acylated.

Dynamic S-acylation of the ER-resident protein stromal interaction molecule 1 (STIM1) is required for store-operated Ca entry.

Many cell surface stimuli cause calcium release from endoplasmic reticulum (ER) stores to regulate cellular physiology. Upon ER calcium store depletion, the ER-resident protein stromal interaction molecule 1 (STIM1) physically interacts with plasma membrane protein Orai1 to induce calcium release-activated calcium (CRAC) currents that conduct calcium influx from the extracellular milieu. Although the physiological relevance of this process is well established, the mechanism supporting the assembly of these proteins is incompletely understood.

Simvastatin modulates estrogen signaling in uterine leiomyoma via regulating receptor palmitoylation, trafficking and degradation.

Uterine leiomyomas or fibroids are the most common tumors of the female reproductive tract. Estrogen (E), a steroid-derived hormone, and its receptors (ERs), particularly ER-α, are important drivers for the development and growth of leiomyomas. We previously demonstrated that simvastatin, a drug used for hyperlipidemia, also possesses anti-leiomyoma properties.

Fatty acid mobilization from adipose tissue is mediated by CD36 posttranslational modifications and intracellular trafficking.

The mechanism controlling long-chain fatty acid (LCFA) mobilization from adipose tissue is not well understood. Here, we investigated how the LCFA transporter CD36 regulates this process. By using tissue-specific KO mouse models, we showed that CD36 in adipocytes and endothelial cells mediated both LCFA deposition into and release from adipose tissue.

S-acylation of Orai1 regulates store-operated Ca2+ entry.

Store-operated Ca2+ entry is a central component of intracellular Ca2+ signaling pathways. The Ca2+ release-activated channel (CRAC) mediates store-operated Ca2+ entry in many different cell types. The CRAC channel is composed of the plasma membrane (PM)-localized Orai1 channel and endoplasmic reticulum (ER)-localized STIM1 Ca2+ sensor.

Ca2+-dependent protein acyltransferase DHHC21 controls activation of CD4+ T cells.

Despite the recognized significance of reversible protein lipidation (S-acylation) for T cell receptor signal transduction, the enzymatic control of this post-translational modification in T cells remains poorly understood. Here, we demonstrate that DHHC21 (also known as ZDHHC21), a member of the DHHC family of mammalian protein acyltransferases, mediates T cell receptor-induced S-acylation of proximal T cell signaling proteins. Using Zdhhc21dep mice, which express a functionally deficient version of DHHC21, we show that DHHC21 is a Ca2+/calmodulin-dependent enzyme critical for activation of naïve CD4+ T cells in response to T cell receptor stimulation.

T cell receptor-dependent S-acylation of ZAP-70 controls activation of T cells.

ZAP-70 is a tyrosine kinase essential for T cell immune responses. Upon engagement of the T cell receptor (TCR), ZAP-70 is recruited to the specialized plasma membrane domains, becomes activated, and is released to phosphorylate its laterally segregated targets. A shift in ZAP-70 distribution at the plasma membrane is recognized as a critical step in TCR signal transduction and amplification.

Activity Dependent Inhibition of AMPA Receptors by Zn.

Zn has been shown to have a wide range of modulatory effects on neuronal AMPARs. However, the mechanism of modulation is largely unknown. Here we show that Zn inhibits GluA2(Q) homomeric receptors in an activity- and voltage-dependent manner, indicating a pore block mechanism.

Regulation of T cell receptor signaling by protein acyltransferase DHHC21.

S-acylation reversible-post-translational lipidation of cysteine residues-is emerging as an important regulatory mechanism in T cell signaling. Dynamic S-acylation is critical for protein recruitment into the T cell receptor complex and initiation of the subsequent signaling cascade. However, the enzymatic control of protein S-acylation in T cells remains poorly understood.

Detection of Protein S-Acylation using Acyl-Resin Assisted Capture.

Protein S-acylation, also referred to as S-palmitoylation, is a reversible post-translational modification of cysteine residues with long-chain fatty acids via a labile thioester bond. S-acylation, which is emerging as a widespread regulatory mechanism, can modulate almost all aspects of the biological activity of proteins, from complex formation to protein trafficking and protein stability. The recent progress in understanding of the biological function of protein S-acylation was achieved largely due to the development of novel biochemical tools allowing robust and sensitive detection of protein S-acylation in a variety of biological samples.

Aggregated and Hyperstable Damage-Associated Molecular Patterns Are Released During ER Stress to Modulate Immune Function.

Chronic ER stress occurs when protein misfolding in the Endoplasmic reticulum (ER) lumen remains unresolved despite activation of the unfolded protein response. We have shown that traumatic injury such as a severe burn leads to chronic ER stress leading to systemic inflammation which can last for more than a year. The mechanisms linking chronic ER stress to systemic inflammatory responses are not clear.

DHHC5 Mediates β-Adrenergic Signaling in Cardiomyocytes by Targeting Gα Proteins.

S-palmitoylation is a reversible posttranslational modification that plays an important role in regulating protein localization, trafficking, and stability. Recent studies have shown that some proteins undergo extremely rapid palmitoylation/depalmitoylation cycles after cellular stimulation supporting a direct signaling role for this posttranslational modification. Here, we investigated whether β-adrenergic stimulation of cardiomyocytes led to stimulus-dependent palmitoylation of downstream signaling proteins.

Rapid and transient palmitoylation of the tyrosine kinase Lck mediates Fas signaling.

Palmitoylation is the posttranslational modification of proteins with a 16-carbon fatty acid chain through a labile thioester bond. The reversibility of protein palmitoylation and its profound effect on protein function suggest that this modification could play an important role as an intracellular signaling mechanism. Evidence that palmitoylation of proteins occurs with the kinetics required for signal transduction is not clear, however.

Caspase 3 cleavage of the inositol 1,4,5-trisphosphate receptor does not contribute to apoptotic calcium release.

An important role in the regulation of apoptotic calcium release is played by the ubiquitously expressed family of inositol 1,4,5-trisphosphate receptor (IP(3)R) channels. One model for IP(3)R activation during apoptosis is cleavage by the apoptotic protease caspase 3. Here we show that early elevations in cytosolic calcium during apoptosis do not require caspase 3 activity.

Monitoring dynamic changes in mitochondrial calcium levels during apoptosis using a genetically encoded calcium sensor.

Dynamic changes in intracellular calcium concentration in response to various stimuli regulates many cellular processes such as proliferation, differentiation, and apoptosis(1). During apoptosis, calcium accumulation in mitochondria promotes the release of pro-apoptotic factors from the mitochondria into the cytosol(2). It is therefore of interest to directly measure mitochondrial calcium in living cells in situ during apoptosis.

T-cell receptor complex is essential for Fas signal transduction.

The Fas receptor (also known as CD95 and APO-1) is a member of the tumor necrosis factor alpha-family of death receptors that mediate T-cell responses. Here, we show that Fas receptor signaling requires a functional T-cell receptor (TCR) complex. Fas receptor directly binds to and activates TCR components in a stimulus-dependent manner.

Chromatin remodeling of interleukin-17 (IL-17)-IL-17F cytokine gene locus during inflammatory helper T cell differentiation.

During differentiation of naive CD4+ helper T (TH) cells into effector cells, specific cytokine gene loci undergo extensive changes in chromatin modification. A novel lineage of TH cells that is regulated by transforming growth factor-beta (TGFbeta) and interleukin-6 (IL-6) has been identified recently as promoting tissue inflammation. These inflammatory TH (THi) cells, also called TH17 or TH(IL-17), produce IL-17 and IL-17F, two highly homologous cytokines that have genes located in the same chromosomal region.