The Roles of Transient Receptor Potential (TRP) Channels Underlying Aberrant Calcium Signaling in Blood-Retinal Barrier Dysfunction.

The inner blood-retinal barrier (iBRB) protects the retinal vasculature from the peripheral circulation. Endothelial cells (ECs) are the core component of the iBRB; their close apposition and linkage via tight junctions limit the passage of fluids, proteins, and cells from the bloodstream to the parenchyma. Dysfunction of the iBRB is a hallmark of many retinal disorders.

Tetrameric, active PKM2 inhibits IP receptors, potentially requiring GRP75 as an additional interaction partner.

Pyruvate kinase M2 (PKM2) is a key glycolytic enzyme interacting with the inositol 1,4,5-trisphosphate receptor (IPR). This interaction suppresses IPR-mediated cytosolic [Ca] rises. As PKM2 exists in monomeric, dimeric and tetrameric forms displaying different properties including catalytic activity, we investigated the molecular determinants of PKM2 enabling its interaction with IPRs.

Sustainability in a broad sense: An essential aspect of scientific conferences.

This article reflects on sustainability in the context of scientific conferences with emphasis on environmental, diversity, inclusivity, and intellectual aspects. We argue that it is imperative to embrace sustainability as a broad concept during conference organization. In-person conferences have an obvious environmental impact but mitigating strategies can be implemented, such as incentivizing low-emission travel, offering fellowships to support sustainable traveling, and promoting use of public transport or car-pooling.

The Complex Effects of PKM2 and PKM2:IPR Disruption on Intracellular Ca Handling and Cellular Functions.

Pyruvate kinase M (PKM) 2 was described to interact with the inositol 1,4,5-trisphosphate (IP) receptor (IPR) and suppress its activity. To further investigate the physiological importance of the PKM2:IPR interaction, we developed and characterized HeLa PKM2 knockout (KO) cells. In the HeLa PKM2 KO cells, the release of Ca to the cytosol appears to be more sensitive to low agonist concentrations than in HeLa wild-type (WT) cells.

Cellular effects of BAPTA: Are they only about Ca chelation?

Intracellular Ca signals play a vital role in a broad range of cell biological and physiological processes in all eukaryotic cell types. Dysregulation of Ca signaling has been implicated in numerous human diseases. Over the past four decades, the understanding of how cells use Ca as a messenger has flourished, largely because of the development of reporters that enable visualization of Ca signals in different cellular compartments, and tools that can modulate cellular Ca signaling.

Intracellular BAPTA directly inhibits PFKFB3, thereby impeding mTORC1-driven Mcl-1 translation and killing MCL-1-addicted cancer cells.

Intracellular Ca signals control several physiological and pathophysiological processes. The main tool to chelate intracellular Ca is intracellular BAPTA (BAPTA), usually introduced into cells as a membrane-permeant acetoxymethyl ester (BAPTA-AM). Previously, we demonstrated that BAPTA enhanced apoptosis induced by venetoclax, a BCL-2 antagonist, in diffuse large B-cell lymphoma (DLBCL).

Calcium signalling pathways in prostate cancer initiation and progression.

Cancer cells proliferate, differentiate and migrate by repurposing physiological signalling mechanisms. In particular, altered calcium signalling is emerging as one of the most widespread adaptations in cancer cells. Remodelling of calcium signalling promotes the development of several malignancies, including prostate cancer.

Quantal leaps in understanding Ca signaling: A "Taylored" approach.

On 2 September 2022, about 85 scientists gathered in person at Queens' College in Cambridge, UK, for a scientific meeting to celebrate the career of Colin W. Taylor of Cambridge University upon his retirement. The meeting was organized by the authors, who are all former graduate students in the Taylor laboratory, which has been at the forefront of Ca signaling for more than 30 years.

A non-canonical role for pyruvate kinase M2 as a functional modulator of Ca signalling through IP receptors.

Pyruvate kinase isoform M2 (PKM2) is a rate-limiting glycolytic enzyme that is widely expressed in embryonic tissues. The expression of PKM2 declines in some tissues following embryogenesis, while other pyruvate kinase isozymes are upregulated. However, PKM2 is highly expressed in cancer cells and is believed to play a role in supporting anabolic processes during tumour formation.

Off-target inhibition of NGLY1 by the polycaspase inhibitor Z-VAD-fmk induces cellular autophagy.

The polycaspase inhibitor Z-VAD-fmk acts as an inhibitor of peptide: N-glycanase (NGLY1), an endoglycosidase which cleaves N-linked glycans from glycoproteins exported from the endoplasmic reticulum (ER) during ER-associated degradation (ERAD). Both pharmacological N-glycanase inhibition by Z-VAD-fmk and siRNA-mediated knockdown (KD) of NGLY1 induce GFP-LC3-positive puncta in HEK 293 cells. The activation of ER stress markers or induction of reactive oxygen species (ROS) is not observed under either condition.

Examining Cardiomyocyte Dysfunction Using Acute Chemical Induction of an Ageing Phenotype.

Much effort is focussed on understanding the structural and functional changes in the heart that underlie age-dependent deterioration of cardiac performance. Longitudinal studies, using aged animals, have pinpointed changes occurring to the contractile myocytes within the heart. However, whilst longitudinal studies are important, other experimental approaches are being advanced that can recapitulate the phenotypic changes seen during ageing.

Cardiac pathology in neuronal ceroid lipofuscinoses (NCL): More than a mere co-morbidity.

The neuronal ceroid lipofuscinoses (NCLs) are mostly seen as diseases affecting the central nervous system, but there is accumulating evidence that they have co-morbidities outside the brain. One of these co-morbidities is a decline in cardiac function. This is becoming increasingly recognised in teenagers and adolescents with juvenile CLN3, but it may also occur in individuals with other NCLs.

Fundamentals of Cellular Calcium Signaling: A Primer.

Ionized calcium (Ca) is the most versatile cellular messenger. All cells use Ca signals to regulate their activities in response to extrinsic and intrinsic stimuli. Alterations in cellular Ca signaling and/or Ca homeostasis can subvert physiological processes into driving pathological outcomes.

T-type calcium channels drive the proliferation of androgen-receptor negative prostate cancer cells.

Background: Androgen deprivation therapy (ADT) is the treatment of choice for metastatic prostate cancer (PCa). After an initial response to ADT, PCa cells can generate castration resistant (CRPC) or neuroendocrine (NEPC) malignancies, which are incurable. T-type calcium channels (TTCCs) are emerging as promising therapeutic targets for several cancers, but their role in PCa progression has never been investigated.

Creating a New Cancer Therapeutic Agent by Targeting the Interaction between Bcl-2 and IP Receptors.

Bcl-2 is a member of a family of proteins that regulate cell survival. Expression of Bcl-2 is aberrantly elevated in many types of cancer. Within cells of the immune system, Bcl-2 has a physiological role in regulating immune responses.

Constitutive IP signaling underlies the sensitivity of B-cell cancers to the Bcl-2/IP receptor disruptor BIRD-2.

Anti-apoptotic Bcl-2 proteins are upregulated in different cancers, including diffuse large B-cell lymphoma (DLBCL) and chronic lymphocytic leukemia (CLL), enabling survival by inhibiting pro-apoptotic Bcl-2-family members and inositol 1,4,5-trisphosphate (IP) receptor (IPR)-mediated Ca-signaling. A peptide tool (Bcl-2/IPR Disruptor-2; BIRD-2) was developed to abrogate the interaction of Bcl-2 with IPRs by targeting Bcl-2's BH4 domain. BIRD-2 triggers cell death in primary CLL cells and in DLBCL cell lines.

Oncogenic KRAS suppresses store-operated Ca entry and I through ERK pathway-dependent remodelling of STIM expression in colorectal cancer cell lines.

The KRAS GTPase plays a fundamental role in transducing signals from plasma membrane growth factor receptors to downstream signalling pathways controlling cell proliferation, survival and migration. Activating KRAS mutations are found in 20% of all cancers and in up to 40% of colorectal cancers, where they contribute to dysregulation of cell processes underlying oncogenic transformation. Multiple KRAS-regulated cell functions are also influenced by changes in intracellular Ca levels that are concurrently modified by receptor signalling pathways.

Deleterious effects of calcium indicators within cells; an inconvenient truth.

The study of cellular Ca signalling is indebted to Roger Tsien for the invention of fluorescent indicators that can be readily loaded into living cells and provide the means to measure cellular Ca changes over long periods of time with sub-second resolution and microscopic precision. However, a recent study [1] reminds us that as useful as these tools are they need to be employed with caution as there can be off-target effects. This article summarises these recent findings within the wider context of confounding issues that can be encountered when using chemical and genetically-encoded Ca indicators, and briefly discusses some approaches that may mitigate against misleading outcomes.

Contractile responses to endothelin-1 are regulated by PKC phosphorylation of cardiac myosin binding protein-C in rat ventricular myocytes.

The shortening of sarcomeres that co-ordinates the pump function of the heart is stimulated by electrically-mediated increases in [Ca]. This process of excitation-contraction coupling (ECC) is subject to modulation by neurohormonal mediators that tune the output of the heart to meet the needs of the organism. Endothelin-1 (ET-1) is a potent modulator of cardiac function with effects on contraction amplitude, chronotropy and automaticity.

Calcium phosphate particles stimulate interleukin-1β release from human vascular smooth muscle cells: A role for spleen tyrosine kinase and exosome release.

Aims: Calcium phosphate (CaP) particle deposits are found in several inflammatory diseases including atherosclerosis and osteoarthritis. CaP, and other forms of crystals and particles, can promote inflammasome formation in macrophages leading to caspase-1 activation and secretion of mature interleukin-1β (IL-1β). Given the close association of small CaP particles with vascular smooth muscle cells (VSMCs) in atherosclerotic fibrous caps, we aimed to determine if CaP particles affected pro-inflammatory signalling in human VSMCs.

Tissue Specificity: Store-Operated Ca Entry in Cardiac Myocytes.

Calcium (Ca) is a key regulator of cardiomyocyte contraction. The Ca channels, pumps, and exchangers responsible for the cyclical cytosolic Ca signals that underlie contraction are well known. In addition to those Ca signaling components responsible for contraction, it has been proposed that cardiomyocytes express channels that promote the influx of Ca from the extracellular milieu to the cytosol in response to depletion of intracellular Ca stores.

The regulation of autophagy by calcium signals: Do we have a consensus?

Macroautophagy (hereafter called 'autophagy') is a cellular process for degrading and recycling cellular constituents, and for maintenance of cell function. Autophagy initiates via vesicular engulfment of cellular materials and culminates in their degradation via lysosomal hydrolases, with the whole process often being termed 'autophagic flux'. Autophagy is a multi-step pathway requiring the interplay of numerous scaffolding and signalling molecules.

Prognostic relevance of a T-type calcium channels gene signature in solid tumours: A correlation ready for clinical validation.

Background: T-type calcium channels (TTCCs) mediate calcium influx across the cell membrane. TTCCs regulate numerous physiological processes including cardiac pacemaking and neuronal activity. In addition, they have been implicated in the proliferation, migration and differentiation of tumour tissues.