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Helgoe J, Davy SK, Weis VM, Rodriguez-Lanetty M. Triggers, cascades, and endpoints: connecting the dots of coral bleaching mechanisms. Biol Rev Camb Philos Soc 2024; 99:715-752. [PMID: 38217089 DOI: 10.1111/brv.13042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 12/08/2023] [Accepted: 12/12/2023] [Indexed: 01/15/2024]
Abstract
The intracellular coral-dinoflagellate symbiosis is the engine that underpins the success of coral reefs, one of the most diverse ecosystems on the planet. However, the breakdown of the symbiosis and the loss of the microalgal symbiont (i.e. coral bleaching) due to environmental changes are resulting in the rapid degradation of coral reefs globally. There is an urgent need to understand the cellular physiology of coral bleaching at the mechanistic level to help develop solutions to mitigate the coral reef crisis. Here, at an unprecedented scope, we present novel models that integrate putative mechanisms of coral bleaching within a common framework according to the triggers (initiators of bleaching, e.g. heat, cold, light stress, hypoxia, hyposalinity), cascades (cellular pathways, e.g. photoinhibition, unfolded protein response, nitric oxide), and endpoints (mechanisms of symbiont loss, e.g. apoptosis, necrosis, exocytosis/vomocytosis). The models are supported by direct evidence from cnidarian systems, and indirectly through comparative evolutionary analyses from non-cnidarian systems. With this approach, new putative mechanisms have been established within and between cascades initiated by different bleaching triggers. In particular, the models provide new insights into the poorly understood connections between bleaching cascades and endpoints and highlight the role of a new mechanism of symbiont loss, i.e. 'symbiolysosomal digestion', which is different from symbiophagy. This review also increases the approachability of bleaching physiology for specialists and non-specialists by mapping the vast landscape of bleaching mechanisms in an atlas of comprehensible and detailed mechanistic models. We then discuss major knowledge gaps and how future research may improve the understanding of the connections between the diverse cascade of cellular pathways and the mechanisms of symbiont loss (endpoints).
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Affiliation(s)
- Joshua Helgoe
- Department of Biological Sciences, Institute of Environment, Florida International University, 11200 SW 8th Street, OE 167, Miami, FL, USA
| | - Simon K Davy
- School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand
| | - Virginia M Weis
- Department of Integrative Biology, Oregon State University, 2701 SW Campus Way, 2403 Cordley Hall, Corvallis, OR, USA
| | - Mauricio Rodriguez-Lanetty
- Department of Biological Sciences, Institute of Environment, Florida International University, 11200 SW 8th Street, OE 167, Miami, FL, USA
- Department of Biological Sciences, Biomolecular Sciences Institute, Florida International University, 11200 SW 8th Street, Miami, FL, USA
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Zhuang Y, Dong H, Liu T, Zhao Y, Xu Y, Zhao X, Sun D. Highly sensitive and selective SERS detection of caspase-3 during cell apoptosis based on the target-induced hotspot effect. Analyst 2024; 149:490-496. [PMID: 38062995 DOI: 10.1039/d3an01721d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2024]
Abstract
Caspase-3 is an important biomarker for the process of apoptosis, which is a key target for cancer treatment. Due to its low concentration in single cells and the structural similarity of caspase family proteins, it is exceedingly challenging to accurately determine the intracellular caspase-3 during apoptosis in situ. Herein, a biosensing strategy based on the target-induced SERS "hot spot" formation has been developed for the simultaneous highly sensitive and selective detection of intracellular caspase-3 level. The nanosensor is composed of gold nanoparticles modified with the probe molecule 4-mercaptophenylboronic acid (4-MPBA) and a peptide chain. The well-designed peptide chain contains two distinct functional domains, one with a sulfhydryl group for bonding to the gold nanoparticles and the other a fragment specifically recognized by caspase-3. When caspase-3 is present, the negatively charged segment (NH2-Asp-Asp-Asp-Glu-Val-Asp-OH) of the peptide chain is specifically hydrolyzed, leaving a positively charged fragment coated on the surface of the gold nanoparticles. At this time, the golden nanoparticles undergo significant coupling aggregation due to the electrostatic interaction, resulting in a large number of SERS "hot spot" formation. The SERS signal of the 4-MPBA located at the nano-gap is significantly boosted because of the local plasma enhancement effect. The highly sensitive determination of caspase-3 can be achieved according to the altered SERS signal intensity of 4-MPBA. The turn-on of the SERS signal-induced target contributes to the excellent selectivity and the formation of the SERS "hot spot" effect that further improves the sensitivity of caspase-3 detection. The advantages of this biosensing technique allow for the precise in situ monitoring of the dynamic changes in caspase-3 levels during apoptosis. In addition, the differences in caspase-3 levels during the apoptosis of various cell types were compared. Monitoring the caspase-3 levels can be used to track the cellular apoptosis process, evaluate the effect of drugs on cancer cells in real time, and provide guidance for the selection of the appropriate drug dosage.
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Affiliation(s)
- Yueyuan Zhuang
- School of Pharmacy, Nantong University, Nantong, Jiangsu, 226001, China.
| | - Han Dong
- School of Pharmacy, Nantong University, Nantong, Jiangsu, 226001, China.
| | - Tianqing Liu
- NICM Health Research Institute, Western Sydney University, Westmead, NSW, 2145, Australia
| | - Yongmei Zhao
- School of Pharmacy, Nantong University, Nantong, Jiangsu, 226001, China.
| | - Yan Xu
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, P.R. China
| | - Xiaojuan Zhao
- School of Materials Engineering, Xi'an Aeronautical University, Xi'an 710077, China.
| | - Dan Sun
- School of Pharmacy, Nantong University, Nantong, Jiangsu, 226001, China.
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Joglekar I, Clark AC. Sequential Unfolding Mechanisms of Monomeric Caspases. Biochemistry 2023; 62:1878-1889. [PMID: 37337671 DOI: 10.1021/acs.biochem.3c00004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2023]
Abstract
Caspases are evolutionarily conserved cysteinyl proteases that are integral in cell development and apoptosis. All apoptotic caspases evolved from a common ancestor into two distinct subfamilies with either monomeric (initiators) or dimeric (effectors) oligomeric states. The regulation of apoptosis is influenced by the activation mechanism of the two subfamilies, but the evolution of the well-conserved caspase-hemoglobinase fold into the two subfamilies is not well understood. We examined the folding landscape of monomeric caspases from two coral species over a broad pH range of 3-10.5. On an evolutionary timescale, the two coral caspases diverged from each other approximately 300 million years ago, and they diverged from human caspases about 600 million years ago. Our results indicate that both proteins have overall high stability, ∼15 kcal mol-1, near the physiological pH range (pH 6-8) and unfold via two partially folded intermediates, I1 and I2*, that are in equilibrium with the native and the unfolded state. Like the dimeric caspases, the monomeric coral caspases undergo a pH-dependent conformational change resulting from the titration of an evolutionarily conserved site. Data from molecular dynamics simulations paired with limited proteolysis and MALDI-TOF mass spectrometry show that the small subunit of the monomeric caspases is unstable and unfolds prior to the large subunit. Overall, the data suggest that all caspases share a conserved folding landscape, that a conserved allosteric site can be fine-tuned for species-specific regulation, and that the subfamily of stable dimers may have evolved to stabilize the small subunit.
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Affiliation(s)
- Isha Joglekar
- Department of Biology, University of Texas at Arlington, Arlington, Texas 76019, United States
| | - A Clay Clark
- Department of Biology, University of Texas at Arlington, Arlington, Texas 76019, United States
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Joglekar I, Clark AC. Sequential unfolding mechanisms of monomeric caspases. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.04.522771. [PMID: 36711547 PMCID: PMC9881926 DOI: 10.1101/2023.01.04.522771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Caspases are evolutionarily conserved cysteinyl proteases that are integral in cell development and apoptosis. All apoptotic caspases evolved from a common ancestor into two distinct subfamilies with either monomeric (initiators) or dimeric (effectors) oligomeric states. The regulation of apoptosis is influenced by the activation mechanism of the two subfamilies, but the evolution of the well-conserved caspase-hemoglobinase fold into the two subfamilies is not well understood. We examined the folding landscape of monomeric caspases from two coral species over a broad pH range of 3 to 10.5. On an evolutionary timescale, the two coral caspases diverged from each other approximately 300 million years ago, and they diverged from human caspases about 600 million years ago. Our results indicate that both proteins have overall high stability, ∼ 15 kcal mol -1 near the physiological pH range (pH 6 to pH 8), and unfold via two partially folded intermediates, I 1 and I 2 , that are in equilibrium with the native and the unfolded state. Like the dimeric caspases, the monomeric coral caspases undergo a pH-dependent conformational change resulting from the titration of an evolutionarily conserved site. Data from molecular dynamics simulations paired with limited proteolysis and MALDI-TOF mass spectrometry show that the small subunit of the monomeric caspases is unstable and unfolds prior to the large subunit. Overall, the data suggest that all caspases share a conserved folding landscape, that a conserved allosteric site can be fine-tuned for species-specific regulation, and that the subfamily of stable dimers may have evolved to stabilize the small subunit.
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Affiliation(s)
- Isha Joglekar
- Department of Biology, University of Texas at Arlington, Arlington, Texas, 76019
| | - A. Clay Clark
- Department of Biology, University of Texas at Arlington, Arlington, Texas, 76019,Corresponding author: A. Clay Clark,
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MacKnight NJ, Dimos BA, Beavers KM, Muller EM, Brandt ME, Mydlarz LD. Disease resistance in coral is mediated by distinct adaptive and plastic gene expression profiles. SCIENCE ADVANCES 2022; 8:eabo6153. [PMID: 36179017 PMCID: PMC9524840 DOI: 10.1126/sciadv.abo6153] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Infectious diseases are an increasing threat to coral reefs, resulting in altered community structure and hindering the functional contributions of disease-susceptible species. We exposed seven reef-building coral species from the Caribbean to white plague disease and determined processes involved in (i) lesion progression, (ii) within-species gene expression plasticity, and (iii) expression-level adaptation among species that lead to differences in disease risk. Gene expression networks enriched in immune genes and cytoskeletal arrangement processes were correlated to lesion progression rates. Whether or not a coral developed a lesion was mediated by plasticity in genes involved in extracellular matrix maintenance, autophagy, and apoptosis, while resistant coral species had constitutively higher expression of intracellular protein trafficking. This study offers insight into the process involved in lesion progression and within- and between-species dynamics that lead to differences in disease risk that is evident on current Caribbean reefs.
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Affiliation(s)
- Nicholas J. MacKnight
- University of Texas at Arlington, 337 Life Science Building, Arlington, TX 76019, USA
| | - Bradford A. Dimos
- University of Texas at Arlington, 337 Life Science Building, Arlington, TX 76019, USA
| | - Kelsey M. Beavers
- University of Texas at Arlington, 337 Life Science Building, Arlington, TX 76019, USA
| | - Erinn M. Muller
- Mote Marine Laboratory, 1600 Ken Thompson Pkwy, Sarasota, FL 34236, USA
| | - Marilyn E. Brandt
- University of the Virgin Islands, 2 John Brewers Bay, St. Thomas, VI 00802, USA
| | - Laura D. Mydlarz
- University of Texas at Arlington, 337 Life Science Building, Arlington, TX 76019, USA
- Corresponding author.
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Shrestha S, Clark AC. Evolution of the folding landscape of effector caspases. J Biol Chem 2021; 297:101249. [PMID: 34592312 PMCID: PMC8628267 DOI: 10.1016/j.jbc.2021.101249] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 09/22/2021] [Accepted: 09/23/2021] [Indexed: 11/07/2022] Open
Abstract
Caspases are a family of cysteinyl proteases that control programmed cell death and maintain homeostasis in multicellular organisms. The caspase family is an excellent model to study protein evolution because all caspases are produced as zymogens (procaspases [PCPs]) that must be activated to gain full activity; the protein structures are conserved through hundreds of millions of years of evolution; and some allosteric features arose with the early ancestor, whereas others are more recent evolutionary events. The apoptotic caspases evolved from a common ancestor (CA) into two distinct subfamilies: monomers (initiator caspases) or dimers (effector caspases). Differences in activation mechanisms of the two subfamilies, and their oligomeric forms, play a central role in the regulation of apoptosis. Here, we examine changes in the folding landscape by characterizing human effector caspases and their CA. The results show that the effector caspases unfold by a minimum three-state equilibrium model at pH 7.5, where the native dimer is in equilibrium with a partially folded monomeric (PCP-7, CA) or dimeric (PCP-6) intermediate. In comparison, the unfolding pathway of PCP-3 contains both oligomeric forms of the intermediate. Overall, the data show that the folding landscape was first established with the CA and was retained for >650 million years. Partially folded monomeric or dimeric intermediates in the ancestral ensemble provide mechanisms for evolutionary changes that affect stability of extant caspases. The conserved folding landscape allows for the fine-tuning of enzyme stability in a species-dependent manner while retaining the overall caspase–hemoglobinase fold.
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Affiliation(s)
- Suman Shrestha
- Department of Biology, University of Texas at Arlington, Arlington, Texas, USA
| | - A Clay Clark
- Department of Biology, University of Texas at Arlington, Arlington, Texas, USA.
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Zhu W, Wang CY, Hu JM, Shen AG. Promoted “Click” SERS Detection for Precise Intracellular Imaging of Caspase-3. Anal Chem 2021; 93:4876-4883. [DOI: 10.1021/acs.analchem.0c04997] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Wei Zhu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China
- School of Printing and Packaging, Wuhan University, Wuhan 430079, P. R. China
| | - Chun-Yang Wang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Ji-Ming Hu
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Ai-Guo Shen
- School of Printing and Packaging, Wuhan University, Wuhan 430079, P. R. China
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