Cancer and pH Dynamics: Transcriptional Regulation, Proteostasis, and the Need for New Molecular Tools

Czowski, Brandon; Romero-Moreno, Ricardo; Trull, Keelan J; White, Katharine A.

doi:10.3390/cancers12102760

Cited by 22 publications

(26 citation statements)

References 133 publications

(144 reference statements)

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“…In normal epithelial cells, intracellular pH (pHi) is regulated between 7.0-7.2, but transient increases in pHi (7.2-7.6) are linked to cell behaviors including cell polarization 1,2 , cytoskeleton remodeling 3,4 , and directed cell migration. 1,2,5,6 However, most studies on pH-dependent cellular behaviors pHi using non-specific methods 7 , which can confound interpretation of biological cause and effect. The lack of appropriate tools to specifically and spatiotemporally manipulate pHi in living cells has obscured our understanding of pHi-dependent regulation of cell behaviors and severely limited identification of the molecular mechanisms underlying pH-dependent behaviors.…”

Section: Introductionmentioning

confidence: 99%

An optogenetic tool to raise intracellular pH in single cells and drive localized membrane dynamics

Donahue

Siroky

White

2021

Preprint

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Intracellular pH (pHi) dynamics are critical for regulating normal cell physiology. For example, transient increases in pHi (7.2-7.6) regulate cell behaviors like cell polarization, actin cytoskeleton remodeling, and cell migration. Most studies on pH-dependent cell behaviors have been performed at the population level and use non-specific methods to manipulate pHi. The lack of tools to specifically manipulate pHi at the single-cell level has hindered investigation of the role of pHi dynamics in driving single cell behaviors. In this work, we show that Archaerhodopsin (ArchT), a light-driven outward proton pump, can be used to elicit robust and physiological pHi increases over the minutes timescale. We show that activation of ArchT is repeatable, enabling the maintenance of high pHi in single cells for approximately 45 minutes. We apply this spatiotemporal pHi manipulation tool to determine whether increased pHi is a sufficient driver of membrane ruffling in single cells. Using the ArchT tool, we show that increased pHi in single cells can drive localized membrane ruffling responses within seconds and 2 increased membrane dynamics (both protrusion and retraction events) compared to control cells. Overall, this tool allows us to directly investigate the relationship between increased pHi and cell behaviors such as membrane ruffling. This tool will be transformative in facilitating the experiments required to determine if increased pHi is a driver of these cell behaviors at the single-cell level.

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Section: Introductionmentioning

confidence: 99%

An optogenetic tool to raise intracellular pH in single cells and drive localized membrane dynamics

Donahue

Siroky

White

2021

Preprint

Self Cite

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“…Changes in pHi control the structure and function of pH-sensitive proteins (aka, pH-sensors) through protonation/ de-protonation, a posttranslational modification akin to phosphorylation, ubiquitination, etc. (36)(37)(38)46). Documented pH-sensors with recurring charge-changing mutations (e.g., Arg to His) include p53, EGF-receptor, Ras-GRP1, and b-catenin (50)(51)(52)(53).…”

Section: Discussionmentioning

confidence: 99%

“…Dysregulated pH represents an under-appreciated hallmark of cancer cells, which display a reversal in the pH gradient controlled by altered proton (H + ) flux (i.e., elevated intracellular pHi and decreased extracellular pHe, the reverse of normal cells) (36)(37)(38)45,46). Functionally, dysregulated pH dynamics modifies cancer cell behaviors, including proliferation, survival, metabolic adaptation, migration, and metastasis.…”

Section: Discussionmentioning

confidence: 99%

“…These key observations enabled us to discover and demonstrate here that alkaline extracellular pH (pHe) increases intracellular pH (pHi), which increases AMPK and mTORC2 signaling to attenuate apoptosis caused by growth factor withdrawal. As elevated pHi represents an under-appreciated hallmark of cancer cells (36)(37)(38), alkaline pH sensing by AMPK-mTORC2 may enable growth factor-and nutrient-deprived cancer cells at the core of a growing tumor to evade apoptosis and survive.…”

Section: Introductionmentioning

confidence: 99%

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Alkaline intracellular pH activates AMPK-mTORC2 signaling to promote cell survival during growth factor limitation

Kazyken

Lentz

Fingar

2021

Preprint

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mTORC2 controls cell metabolism and promotes cell survival, yet its upstream regulation by diverse cellular cues remains poorly defined. While considerable evidence indicates that mTORC1 but not mTORC2 responds dynamically to amino acid levels, several studies reported activation of mTORC2 signaling by amino acids, a paradox that remains unresolved. Following amino acid starvation, we noted that addition of a commercial amino acid solution but not re-feeding with DMEM containing amino acids increased mTORC2 signaling. Interestingly, the pH of the amino acid solution was ~ 10. These key observations enabled us to discover that alkaline intracellular pH (pHi) represents a previously unknown activator of mTORC2. Using a fluorescent pH-sensitive dye (cSNARF-1-AM) coupled to live-cell imaging, we demonstrate that alkaline extracellular pH (pHe) increases intracellular pHi, which increases mTORC2 catalytic activity and downstream signaling to Akt. Alkaline pHi also activates AMPK, a sensor of energetic stress. Functionally, alkaline pHi attenuates apoptosis caused by growth factor withdrawal, which requires AMPK in part and mTOR in full. Collectively, these findings reveal that alkaline pHi increases AMPK-mTORC2 signaling to promote cell survival during growth factor limitation. As elevated pHi represents an under-appreciated hallmark of cancer cells, alkaline pH sensing by AMPK-mTORC2 may contribute to tumorigenesis.

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“…These proteins function as intracellular pH detectors must not be cytotoxic, nor invasive; and should not interfere with cellular metabolic pathways [ 102 ]. For medical purpose the ability to reveal the pH in microenvironment for diagnostic purpose of cancer and allow for selective efficiency for live-cell microscopy [ 103 , 104 , 105 ]. A variety of protein-based pH VSs were developed since the discovery of the amazing properties of the green fluorescent proteins (GFPs, see Section 5.1 ).…”

Section: Bioengineered Visual Ph Sensorsmentioning

confidence: 99%

Visual pH Sensors: From a Chemical Perspective to New Bioengineered Materials

Costanzo

Panunzi

2021

Molecules

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Many human activities and cellular functions depend upon precise pH values, and pH monitoring is considered a fundamental task. Colorimetric and fluorescence sensors for pH measurements are chemical and biochemical tools able to sense protons and produce a visible signal. These pH sensors are gaining widespread attention as non-destructive tools, visible to the human eye, that are capable of a real-time and in-situ response. Optical “visual” sensors are expanding researchers’ interests in many chemical contexts and are routinely used for biological, environmental, and medical applications. In this review we provide an overview of trending colorimetric, fluorescent, or dual-mode responsive visual pH sensors. These sensors include molecular synthetic organic sensors, metal organic frameworks (MOF), engineered sensing nanomaterials, and bioengineered sensors. We review different typological chemical entities of visual pH sensors, three-dimensional structures, and signaling mechanisms for pH sensing and applications; developed in the past five years. The progression of this review from simple organic molecules to biological macromolecules seeks to benefit beginners and scientists embarking on a project of pH sensing development, who needs background information and a quick update on advances in the field. Lessons learned from these tools will aid pH determination projects and provide new ways of thinking for cell bioimaging or other cutting-edge in vivo applications.

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Cancer and pH Dynamics: Transcriptional Regulation, Proteostasis, and the Need for New Molecular Tools

Cited by 22 publications

References 133 publications

An optogenetic tool to raise intracellular pH in single cells and drive localized membrane dynamics

An optogenetic tool to raise intracellular pH in single cells and drive localized membrane dynamics

Alkaline intracellular pH activates AMPK-mTORC2 signaling to promote cell survival during growth factor limitation

Visual pH Sensors: From a Chemical Perspective to New Bioengineered Materials

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