Malena Espanol explains how she and others use linear algebra to correct blurry images. Imagine snapping a quick picture of a flying bird. The image is likely to come out blurry. But thanks to mathematics, you might be able to use software to improve the photo. Scientists often deal with blurry pictures, too. Linear algebra and clever numerical methods allow researchers to fix imperfect photos in medical imaging, astronomy, and more. In a computer, the pixels that make up an image can be represented as a column of numbers called a vector. Blurring happens when the light meant for each pixel spills into the adjacent pixels, changing the numbers in a way that can be mathematically represented as an enormous matrix. But knowing that matrix is not enough if you want to reconstruct the original (non-blurry) image.

We are extremely excited to announce on behalf of the American Society for Biochemistry and Molecular Biology (ASBMB) that the Journal of Biological Chemistry (JBC), Molecular & Cellular Proteomics (MCP), and the Journal of Lipid Research (JLR) will be published as fully open-access journals beginning in January 2021. This is a landmark decision that will have huge impact for readers and authors. As many of you know, many researchers have called for journals to become open access to facilitate scientific progress, and many funding agencies across the globe are either already requiring or considering a requirement that all scientific publications based on research they support be published in open-access journals. The ASBMB journals have long supported open access, making the accepted author versions of manuscripts immediately and permanently available, allowing authors to opt in to the immediate open publication of the final version of their paper, and endorsing the goals of the larger open-access movement (1). However, we are no longer satisfied with these measures. To live up to our goals as a scientific society, we want to freely distribute the scientific advances published in JBC, MCP, and JLR as widely and quickly as possible to support the scientific community. How better can we facilitate the dissemination of new information than to make our scientific content freely open to all?For ASBMB journals and others who have contemplated or made the transition to publishing all content open access, achieving this milestone generally requires new financial mechanisms. In the case of the...

Soun-Hi Kwon
Trans. Amer. Math. Soc. 377 (), 6021-6022.
Abstract, references and article information

Noga Alon, Anurag Bishnoi, Shagnik Das and Alessandro Neri
Trans. Amer. Math. Soc. 377 (), 5389-5410.
Abstract, references and article information

Daniel López Neumann
Trans. Amer. Math. Soc. 377 (), 5361-5387.
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Ning Jiang, Yi-Long Luo and Shaojun Tang
Trans. Amer. Math. Soc. 377 (), 5323-5359.
Abstract, references and article information

dannyhennesy posted a photo:

On the Capital planet the rebellious droids had followed maily the Bat-Bot, but as time progressed his circuits had gone all mushy at 780 years or so without maintenance…

Several splinter groups all with their local bot leaders emerged such as the Che-bot, the traffic-light-robot and the Butt-bot, but none of these collected enough sentient circuits to call themselves a popular (or Animata) mass movement!

That was until a cyborg came along, one known as Jones, a long time prisoner and terrorist, his easy solutions to every problem rang well in the masses' auditory circuits!!!

His slogans and simple rhetoric were simple enough for the simple traffic-light to comprehend and cheer!

His language was full of hate towards the organics and especially the humans who were the most common races among the ruling class of the federation!!!

Despite being a “Fleshie” himself his message collected the angry enslaved
bot community by only weeks all rebellious robots except for a few fringe loonies had forgotten the old leaders…

One morning at Jones gave the signal…

All over the capital planet hordes and swarms of any form of mechanical sentient beings attacked first the police stations, then the Company boards running the planet and the federation as well as their starfleet…

Many died, especially the low level police and army! Many mechanicals died too, but their ranks were soon filled by Mutant fleshie allies of the lower levels who hated the Federation feudal society and upper classes as much as their technological allies…

The Federation state apparatus and ruling class, most of their fleet army fled when they knew the game was up, they activated the emergency escape plan and whole city blocks with important factories, administrational units, valuable assets and so on separated from the capital by hidden rocket engines and homed in their course to Mars…

On Mars the federation regrouped and formed their new society…

On the Capital planet, the robots proclaimed the first Techno-republic of the advanced inorganic civilization, the low level fleshies left behind, became slaves and their mutant allies got to rule their own minute chiefdoms as protectorates under the Techno-republic…

Jones was now the undisputed ruler of the capital planet, but the victory was a pyrros one since, all important buildings, all of value was now one Mars!

But as Jones put it:

Our proud race the Techno-species didn’t need the Fleshies administration, their infrastructure, their spaceships…

We shall start from scratch, with a new administration, a new order, every droid shall work at 4x speed than they did during human oppression since now we are free and the fleshies shall work twice as hard than the Techno-Race, until we have breed enough new fleshies so they can do all work!

Our future is bright and shiny like glistering shiny metal!

The snapshot seen here is from the first police station attacked in sector 45-34v-ss-g the first one to fall according to official techno-history!

———————————————/
Designers note:

I am sad to say that this is the last episode in this years-spanning space series… At least for a while, I will still post LEGO hobby stuff here but without a storyline, perhaps small designs and builds… and occasionally a story when I feel like it!!!

I would like to thank all who had been in this journey of our heros, but it has taken far to much time and effort and since the state of the world is as it is, I am spiraling down in another depression, I must stop it before I reach the abyss, so I have remove some stress out of my equation… I ended it in a cliffhanger so I can easily restart it when my mental health improves… I hope that won’t be forever???

I would love if someone used my characters or ideas, please send me a link if you do, I would love to read it or look at it!!!

But there will be more Lego, just in different format without long stories, I need to focus more on my art and to be honest that is the only time the mental pain eases, when I create!!!


Peace and Noise!

MushroomBrain a FOL

Denise Uwamariya and Xiangfeng Yang
Theor. Probability and Math. Statist. 111 (), 167-179.
Abstract, references and article information

Ta Cong Son, Tran Manh Cuong, Le Quang Dung and Le Van Dung
Theor. Probability and Math. Statist. 111 (), 153-165.
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Abdessamad Dehaj and Mohamed Guessous
Theor. Probability and Math. Statist. 111 (), 1-8.
Abstract, references and article information

Shengyu Tang
Proc. Amer. Math. Soc. 152 (), 5381-5394.
Abstract, references and article information

Anh Tuan Nguyen, Tómas Caraballo and Nguyen Huy Tuan
Proc. Amer. Math. Soc. 152 (), 5175-5189.
Abstract, references and article information

Benjamin Jaye and Manasa N. Vempati
Proc. Amer. Math. Soc. 152 (), 5105-5116.
Abstract, references and article information

Roland Donninger
Bull. Amer. Math. Soc. 61 (), 659-685.
Abstract, references and article information

Dynamic singer Tosh Alexander has been lighting up the music scene with her latest track, ' My Ting Different', a thrilling collaboration with American rapper and songwriter Lady London. The song fuses R...

When a scuba diver comes up from the deep too quickly, the rapid decrease in pressure can give them a case of "the bends" or decompression sickness. It is caused by bubbles of gas building up in the body, causing pain. It can also be fatal....

After parking his taxi cab along the sidewalk, Leon Thompson exited his vehicle and held on tightly to the tiny hands of his four small passengers. They all walked towards a makeshift bridge, and Thompson lifted each child, making four trips,...

Twenty-eight-year-old labourer Michael Ennis, of Manning's Hill district in Manchester, has been charged with smoking ganja in a public place following an incident in May Pen, Clarendon on Monday.

Carnosine (β-alanyl-l-histidine) and anserine (β-alanyl-3-methyl-l-histidine) are abundant peptides in the nervous system and skeletal muscle of many vertebrates. Many in vitro and in vivo studies demonstrated that exogenously added carnosine can improve muscle contraction, has antioxidant activity, and can quench various reactive aldehydes. Some of these functions likely contribute to the proposed anti-aging activity of carnosine. However, the physiological role of carnosine and related histidine-containing dipeptides (HCDs) is not clear. In this study, we generated a mouse line deficient in carnosine synthase (Carns1). HCDs were undetectable in the primary olfactory system and skeletal muscle of Carns1-deficient mice. Skeletal muscle contraction in these mice, however, was unaltered, and there was no evidence for reduced pH-buffering capacity in the skeletal muscle. Olfactory tests did not reveal any deterioration in 8-month-old mice lacking carnosine. In contrast, aging (18–24-month-old) Carns1-deficient mice exhibited olfactory sensitivity impairments that correlated with an age-dependent reduction in the number of olfactory receptor neurons. Whereas we found no evidence for elevated levels of lipoxidation and glycation end products in the primary olfactory system, protein carbonylation was increased in the olfactory bulb of aged Carns1-deficient mice. Taken together, these results suggest that carnosine in the olfactory system is not essential for information processing in the olfactory signaling pathway but does have a role in the long-term protection of olfactory receptor neurons, possibly through its antioxidant activity.

α-Linked galactose is a common carbohydrate motif in nature that is processed by a variety of glycoside hydrolases from different families. Terminal Galα1–3Gal motifs are found as a defining feature of different blood group and tissue antigens, as well as the building block of the marine algal galactan λ-carrageenan. The blood group B antigen and linear α-Gal epitope can be processed by glycoside hydrolases in family GH110, whereas the presence of genes encoding GH110 enzymes in polysaccharide utilization loci from marine bacteria suggests a role in processing λ-carrageenan. However, the structure–function relationships underpinning the α-1,3-galactosidase activity within family GH110 remain unknown. Here we focus on a GH110 enzyme (PdGH110B) from the carrageenolytic marine bacterium Pseudoalteromonas distincta U2A. We showed that the enzyme was active on Galα1–3Gal but not the blood group B antigen. X-ray crystal structures in complex with galactose and unhydrolyzed Galα1–3Gal revealed the parallel β-helix fold of the enzyme and the structural basis of its inverting catalytic mechanism. Moreover, an examination of the active site reveals likely adaptations that allow accommodation of fucose in blood group B active GH110 enzymes or, in the case of PdGH110, accommodation of the sulfate groups found on λ-carrageenan. Overall, this work provides insight into the first member of a predominantly marine clade of GH110 enzymes while also illuminating the structural basis of α-1,3-galactoside processing by the family as a whole.

The bacterial enhancer-binding protein (bEBP) FlrC, controls motility and colonization of Vibrio cholerae by regulating the transcription of class-III flagellar genes in σ54-dependent manner. However, the mechanism by which FlrC regulates transcription is not fully elucidated. Although, most bEBPs require nucleotides to stimulate the oligomerization necessary for function, our previous study showed that the central domain of FlrC (FlrCC) forms heptamer in a nucleotide-independent manner. Furthermore, heptameric FlrCC binds ATP in “cis-mediated” style without any contribution from sensor I motif 285REDXXYR291 of the trans protomer. This atypical ATP binding raises the question of whether heptamerization of FlrC is solely required for transcription regulation, or if it is also critical for ATPase activity. ATPase assays and size exclusion chromatography of the trans-variants FlrCC-Y290A and FlrCC-R291A showed destabilization of heptameric assembly with concomitant abrogation of ATPase activity. Crystal structures showed that in the cis-variant FlrCC-R349A drastic shift of Walker A encroached ATP-binding site, whereas the site remained occupied by ADP in FlrCC-Y290A. We postulated that FlrCC heptamerizes through concentration-dependent cooperativity for maximal ATPase activity and upon heptamerization, packing of trans-acting Tyr290 against cis-acting Arg349 compels Arg349 to maintain proper conformation of Walker A. Finally, a Trp quenching study revealed binding of cyclic-di-GMP with FlrCC. Excess cyclic-di-GMP repressed ATPase activity of FlrCC through destabilization of heptameric assembly, especially at low concentration of protein. Systematic phylogenetic analysis allowed us to propose similar regulatory mechanisms for FlrCs of several Vibrio species and a set of monotrichous Gram-negative bacteria.

The dimeric ectonucleotidase CD73 catalyzes the hydrolysis of AMP at the cell surface to form adenosine, a potent suppressor of the immune response. Blocking CD73 activity in the tumor microenvironment can have a beneficial effect on tumor eradication and is a promising approach for cancer therapy. Biparatopic antibodies binding different regions of CD73 may be a means to antagonize its enzymatic activity. A panel of biparatopic antibodies representing the pairwise combination of 11 parental monoclonal antibodies against CD73 was generated by Fab-arm exchange. Nine variants vastly exceeded the potency of their parental antibodies with ≥90% inhibition of activity and subnanomolar EC50 values. Pairing the Fabs of parents with nonoverlapping epitopes was both sufficient and necessary whereas monovalent antibodies were poor inhibitors. Some parental antibodies yielded potent biparatopics with multiple partners, one of which (TB19) producing the most potent. The structure of the TB19 Fab with CD73 reveals that it blocks alignment of the N- and C-terminal CD73 domains necessary for catalysis. A separate structure of CD73 with a Fab (TB38) which complements TB19 in a particularly potent biparatopic shows its binding to a nonoverlapping site on the CD73 N-terminal domain. Structural modeling demonstrates a TB19/TB38 biparatopic antibody would be unable to bind the CD73 dimer in a bivalent manner, implicating crosslinking of separate CD73 dimers in its mechanism of action. This ability of a biparatopic antibody to both crosslink CD73 dimers and fix them in an inactive conformation thus represents a highly effective mechanism for the inhibition of CD73 activity.

The life cycle of malaria parasites in both their mammalian host and mosquito vector consists of multiple developmental stages that ensure proper replication and progeny survival. The transition between these stages is fueled by nutrients scavenged from the host and fed into specialized metabolic pathways of the parasite. One such pathway is used by Plasmodium falciparum, which causes the most severe form of human malaria, to synthesize its major phospholipids, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine. Much is known about the enzymes involved in the synthesis of these phospholipids, and recent advances in genetic engineering, single-cell RNA-Seq analyses, and drug screening have provided new perspectives on the importance of some of these enzymes in parasite development and sexual differentiation and have identified targets for the development of new antimalarial drugs. This Minireview focuses on two phospholipid biosynthesis enzymes of P. falciparum that catalyze phosphoethanolamine transmethylation (PfPMT) and phosphatidylserine decarboxylation (PfPSD) during the blood stages of the parasite. We also discuss our current understanding of the biochemical, structural, and biological functions of these enzymes and highlight efforts to use them as antimalarial drug targets.

16 July 2020

Methionine, through S-adenosylmethionine, activates a multifaceted growth program in which ribosome biogenesis, carbon metabolism, and amino acid and nucleotide biosynthesis are induced. This growth program requires the activity of the Gcn4 transcription factor (called ATF4 in mammals), which facilitates the supply of metabolic precursors that are essential for anabolism. However, how Gcn4 itself is regulated in the presence of methionine is unknown. Here, we discover that Gcn4 protein levels are increased by methionine, despite conditions of high cell growth and translation (in which the roles of Gcn4 are not well-studied). We demonstrate that this mechanism of Gcn4 induction is independent of transcription, as well as the conventional Gcn2/eIF2α-mediated increased translation of Gcn4. Instead, when methionine is abundant, Gcn4 phosphorylation is decreased, which reduces its ubiquitination and therefore degradation. Gcn4 is dephosphorylated by the protein phosphatase 2A (PP2A); our data show that when methionine is abundant, the conserved methyltransferase Ppm1 methylates and alters the activity of the catalytic subunit of PP2A, shifting the balance of Gcn4 toward a dephosphorylated, stable state. The absence of Ppm1 or the loss of the PP2A methylation destabilizes Gcn4 even when methionine is abundant, leading to collapse of the Gcn4-dependent anabolic program. These findings reveal a novel, methionine-dependent signaling and regulatory axis. Here methionine directs the conserved methyltransferase Ppm1 via its target phosphatase PP2A to selectively stabilize Gcn4. Through this, cells conditionally modify a major phosphatase to stabilize a metabolic master regulator and drive anabolism.

Oxygen regulates hypoxia-inducible factor (HIF) transcription factors to control cell metabolism, erythrogenesis, and angiogenesis. Whereas much has been elucidated about how oxygen regulates HIF, whether lipids affect HIF activity is un-known. Here, using cultured cells and two animal models, we demonstrate that lipoprotein-derived fatty acids are an independent regulator of HIF. Decreasing extracellular lipid supply inhibited HIF prolyl hydroxylation, leading to accumulation of the HIFα subunit of these heterodimeric transcription factors comparable with hypoxia with activation of downstream target genes. The addition of fatty acids to culture medium suppressed this signal, which required an intact mitochondrial respiratory chain. Mechanistically, fatty acids and oxygen are distinct signals integrated to control HIF activity. Finally, we observed lipid signaling to HIF and changes in target gene expression in developing zebrafish and adult mice, and this pathway operates in cancer cells from a range of tissues. This study identifies fatty acids as a physiological modulator of HIF, defining a mechanism for lipoprotein regulation that functions in parallel to oxygen.

Poly(ADP-ribose) polymerase (PARP) superfamily members covalently link either a single ADP-ribose (ADPR) or a chain of ADPR units to proteins using NAD as the source of ADPR. Although the well-known poly(ADP-ribosylating) (PARylating) PARPs primarily function in the DNA damage response, many noncanonical mono(ADP-ribosylating) (MARylating) PARPs are associated with cellular antiviral responses. We recently demonstrated robust up-regulation of several PARPs following infection with murine hepatitis virus (MHV), a model coronavirus. Here we show that SARS-CoV-2 infection strikingly up-regulates MARylating PARPs and induces the expression of genes encoding enzymes for salvage NAD synthesis from nicotinamide (NAM) and nicotinamide riboside (NR), while down-regulating other NAD biosynthetic pathways. We show that overexpression of PARP10 is sufficient to depress cellular NAD and that the activities of the transcriptionally induced enzymes PARP7, PARP10, PARP12 and PARP14 are limited by cellular NAD and can be enhanced by pharmacological activation of NAD synthesis. We further demonstrate that infection with MHV induces a severe attack on host cell NAD+ and NADP+. Finally, we show that NAMPT activation, NAM, and NR dramatically decrease the replication of an MHV that is sensitive to PARP activity. These data suggest that the antiviral activities of noncanonical PARP isozyme activities are limited by the availability of NAD and that nutritional and pharmacological interventions to enhance NAD levels may boost innate immunity to coronaviruses.

A new vision for African agency in sustainable development Expert comment LJefferson 18 October 2022

Change is necessary not only in global economic structures and attitudes – but in African governance too.

The conventional notion that Africa is mostly a consumer of norms and practices designed by the Global North has been repeatedly challenged and is increasingly being debunked. Increased African agency in international affairs is today a well-established and documented reality. But Africa’s influence still does not match the scale of the challenges that it faces on its pathway to sustainable development. 

Pushing for African agency in sustainable development also warrants a critical assessment of how ‘sustainable development’ should be defined, and how it can be achieved in terms of actual poverty reduction and real improvement in the lives of local poor Africans. Sustainable development has been a political catchphrase for over 30 years – but a genuine transition towards sustainability has yet to begin.

African agency today

Historically, there have been structural limitations on the agency of African stakeholders to shape development pathways. Chief among them, donor-recipient power dynamics have persistently promoted dependency and sustained institutional corruption. Many African countries are also challenged by economic incentives and infrastructure that have favoured the market demands and supply chains of former colonial powers, which largely remain reliant on natural resource extraction, and are marked by limited investment in value-addition activities and technology development.

Today, however, African agency is being exerted in a more assertive fashion. The African Union (AU), individual African states, civil society, the private sector and eminent and ordinary persons are all displaying Africa’s agency in steering global sustainable development priorities, namely by proposing their own development agenda, The African Union Agenda 2063, adopted in 2013. This was followed by the UN Sustainable Development Goals (Agenda 2030), which in many ways mirror Agenda 2063 – a clear demonstration of the influence of Africa in the global arena. 

Agenda 2063 is a strategic roadmap for Africa ‘to build an integrated, prosperous and peaceful Africa, driven and managed by its own citizens and development goals representing a dynamic force in the international arena’. Prepared following a broad-based participatory consultation, it advocates for inclusion and empowerment and provides an excellent vision for African countries and African people. The SDGs address several of the key shortcomings of their predecessor – the MDGs – and incorporate a broader and more transformative agenda that more adequately reflects the complex challenges of the 21st century and the need for structural reforms in the global economy and governance norms.

In international forums on sustainable development, African countries are increasingly using their collective voice to change the discourse on how development can and should be done. For instance, by championing innovative solutions for carbon markets, African policy leaders are enabling access to climate finance for development while preserving Africa’s natural wealth.

In the post-COVID era, championing investments in and leadership of Africa’s global health architecture demonstrates a desire that in the next pandemic, Africa CDC, AMA and continental manufacturers will play leading roles in determining Africa’s public health strategy and implementation.

In trade, building on the groundwork led by the regional economic commissions, the AfCFTA will catalyse and scale regional integration, trade and cooperation, leading to promising new modes of supply chain and self-sufficiency.

Encouraging signs, but persistent shortcomings

Encouraging signs that African agency is gaining momentum cannot disguise the fact that Africa has yet to move from rhetoric to implementation in the realm of sustainable development. Continental visions often fail to go beyond declarations of intent, and have only limited influence on governance systems or national structural transformation, and African states remain vulnerable to economic shocks emanating from the global system.

Change will require governance systems that are coordinated, transparent, efficient, and inclusive, as well as tools, processes, and means (material, technical, and human) for successful implementation. There is an urgent need for a new governance paradigm in Africa and internationally, dealing with long-term social change.

Notably, African agency should not be only seen as emanating from government, but also as being exerted by independent civil society organizations and committed ordinary individuals. Effective agency needs to be multi-faceted and multi-actor, and depends on the inclusiveness of African governments and their willingness to work with civil society in their strategic engagements with external partners.

Both Agenda 2063 and the SDGs hold the potential for transformation, but implementation will depend on continued advocacy to hold authorities to account and change the dominant discourse, logic and rules of engagement at global, regional, national, and local levels. There is a need for a dynamic new model of African ‘development’.

Time for a new vision

Africa’s economic landscape is changing rapidly, with new regional and local value chains, and integrated regional economic corridors to link countries, minimize the burden of high-cost production and logistics, and boost real incomes and international competitiveness. But Africa continues to face structural challenges, including the need for large investment projects – at a time when Africa remains a net exporter of capital.

Donors and development partners must reflect upon their prior modes of engagement and commit to genuine and equitable relationships with African states. Such partnerships must reflect mutual respect of ideas and accountability, and commit to making space in international forums and multi-lateral arrangements for African people and countries to realize their own visions for progress.

But African leaders and actors must also recognize that with the advent of resources and agency comes responsibility for results and outcomes, notably the need to improve governance. Gaps in accountability, widespread corruption, and lack of successful implementation and sustainability of projects must be addressed.

Visual Abstract

Visual Abstract

Wenhe Zhu
Dec 29, 2020; 0:RA120.002353v1-mcp.RA120.002353
Research

Yadong Yu
Dec 1, 2020; 19:1997-2014
Research

Alba Simats
Dec 1, 2020; 19:1921-1935
Research

Weixian Deng
Dec 22, 2020; 0:RA120.002411v1-mcp.RA120.002411
Research

Philipp Emanuel Geyer
Dec 17, 2020; 0:RA120.002359v1-mcp.RA120.002359
Research

Large regions in tumor tissues, particularly pancreatic cancer, are hypoxic and nutrient-deprived because of unregulated cell growth and insufficient vascular supply. Certain cancer cells, such as those inside a tumor, can tolerate these severe conditions and survive for prolonged periods. We hypothesized that small molecular agents, which can preferentially reduce cancer cell survival under nutrient-deprived conditions, could function as anticancer drugs. In this study, we constructed a high-throughput screening system to identify such small molecules and screened chemical libraries and microbial culture extracts. We were able to determine that some small molecular compounds, such as penicillic acid, papyracillic acid, and auranofin, exhibit preferential cytotoxicity to human pancreatic cancer cells under nutrient-deprived compared with nutrient-sufficient conditions. Further analysis revealed that these compounds target to redox systems such as GSH and thioredoxin and induce accumulation of reactive oxygen species in nutrient-deprived cancer cells, potentially contributing to apoptosis under nutrient-deprived conditions. Nutrient-deficient cancer cells are often deficient in GSH; thus, they are susceptible to redox system inhibitors. Targeting redox systems might be an attractive therapeutic strategy under nutrient-deprived conditions of the tumor microenvironment.

Transient receptor potential vanilloid 1 (TRPV1) channel is a multimodal receptor that is responsible for nociceptive, thermal, and mechanical sensations. However, which biomolecular partners specifically interact with TRPV1 remains to be elucidated. Here, we used cDNA library screening of genes from mouse dorsal root ganglia combined with patch-clamp electrophysiology to identify the voltage-gated potassium channel auxiliary subunit Kvβ1 physically interacting with TRPV1 channel and regulating its function. The interaction was validated in situ using endogenous dorsal root ganglia neurons, as well as a recombinant expression model in HEK 293T cells. The presence of Kvβ1 enhanced the expression stability of TRPV1 channels on the plasma membrane and the nociceptive current density. Surprisingly, Kvβ1 interaction also shifted the temperature threshold for TRPV1 thermal activation. Using site-specific mapping, we further revealed that Kvβ1 interacted with the membrane-distal domain and membrane-proximal domain of TRPV1 to regulate its membrane expression and temperature-activation threshold, respectively. Our data therefore suggest that Kvβ1 is a key element in the TRPV1 signaling complex and exerts dual regulatory effects in a site-specific manner.

Mutations in the GUCY2D gene coding for the dimeric human retinal membrane guanylyl cyclase (RetGC) isozyme RetGC1 cause various forms of blindness, ranging from rod dysfunction to rod and cone degeneration. We tested how the mutations causing recessive congenital stationary night blindness (CSNB), recessive Leber's congenital amaurosis (LCA1), and dominant cone–rod dystrophy-6 (CORD6) affected RetGC1 activity and regulation by RetGC-activating proteins (GCAPs) and retinal degeneration-3 protein (RD3). CSNB mutations R666W, R761W, and L911F, as well as LCA1 mutations R768W and G982VfsX39, disabled RetGC1 activation by human GCAP1, -2, and -3. The R666W and R761W substitutions compromised binding of GCAP1 with RetGC1 in HEK293 cells. In contrast, G982VfsX39 and L911F RetGC1 retained the ability to bind GCAP1 in cyto but failed to effectively bind RD3. R768W RetGC1 did not bind either GCAP1 or RD3. The co-expression of GUCY2D allelic combinations linked to CSNB did not restore RetGC1 activity in vitro. The CORD6 mutation R838S in the RetGC1 dimerization domain strongly dominated the Ca2+ sensitivity of cyclase regulation by GCAP1 in RetGC1 heterodimer produced by co-expression of WT and the R838S subunits. It required higher Ca2+ concentrations to decelerate GCAP-activated RetGC1 heterodimer—6-fold higher than WT and 2-fold higher than the Ser838-harboring homodimer. The heterodimer was also more resistant than homodimers to inhibition by RD3. The observed biochemical changes can explain the dominant CORD6 blindness and recessive LCA1 blindness, both of which affect rods and cones, but they cannot explain the selective loss of rod function in recessive CSNB.

Ryunosuke Ohkawa
Dec 1, 2020; 61:1577-1588
Research Articles