Rescue of ΔF508-CFTR trafficking via a GRASP-dependent unconventional secretion pathway.

The most prevalent disease-causing mutation of CFTR is the deletion of Phe508 (ΔF508), which leads to defects in conventional Golgi-mediated exocytosis and cell surface expression. We report that ΔF508-CFTR surface expression can be rescued in vitro and in vivo by directing it to an unconventional GRASP-dependent secretion pathway. An integrated molecular and physiological analysis indicates that mechanisms associated with ER stress induce cell surface trafficking of the ER core-glycosylated wild-type and ΔF508-CFTR via the GRASP-dependent pathway. Phosphorylation of a specific site of GRASP and the PDZ-based interaction between GRASP and CFTR are critical for this unconventional surface trafficking. Remarkably, transgenic expression of GRASP in ΔF508-CFTR mice restores CFTR function and rescues mouse survival without apparent toxicity. These findings provide insight into how unconventional protein secretion is activated, and offer a potential therapeutic strategy for the treatment of cystic fibrosis and perhaps diseases stemming from other misfolded proteins.

Potential Issues in Mandating a Disclosure of Institutional Investigation in Retraction Notices.

A retraction notice is a formal announcement for the removal of a paper from the literature, which is a weighty matter. Xu et al. (Science and Engineering Ethics, 29(4), 25 2023) reported that 73.7% of retraction notices indexed by the Web of Science (1927-2019) provided no information about institutional investigations that may have led to the retractions, and recommended that Committee on Publication Ethics (COPE) retraction guidelines should make it mandatory to disclose institutional investigations leading to retractions in such notices. While this recommendation would add to the transparency of the retraction process, a blanket mandate as such could be potentially problematic. For research misconduct (RM)-positive cases, a mandatory investigative disclosure may be abused by some to deflect responsibility. More importantly, a mandatory disclosure could harm authors and institutions in RM-negative cases (i.e. those stemming from honest errors with no misconduct). I illustrate with case vignettes the potential epistemic injustice and confusion that a mandate for investigation disclosure in retraction notices could incur, and suggest a more nuanced approach to its implementation.

Debates on humanization of human-animal brain chimeras - are we putting the cart before the horses?

Research on human-animal chimeras have elicited alarms and prompted debates. Those involving the generation of chimeric brains, in which human brain cells become anatomically and functionally intertwined with their animal counterparts in varying ratios, either via xenografts or embryonic co-development, have been considered the most problematic. The moral issues stem from a potential for "humanization" of the animal brain, as well as speculative changes to the host animals' consciousness or sentience, with consequential alteration in the animal hosts' moral status. However, critical background knowledge appears to be missing to resolve these debates. Firstly, there is no consensus on animal sentience vis-à-vis that of humans, and no established methodology that would allow a wholesome and objective assessment of changes in animal sentience resulting from the introduction of human brain cells. Knowledge in interspecies comparative neuropsychology that could allow effective demarcation of a state of "humanization" is also lacking. Secondly, moral status as a philosophical construct has no scientific and objective points of reference. Either changes in sentience or humanization effects would remain unclear unless there are some neuroscientific research grounding. For a bioethical stance based on moral status of human-animal brain chimera to make meaningful contributions to regulatory policies, it might first need to be adequately informed by, and with its arguments constructed, in a manner that are factually in line with the science. In may be prudent for approved research projects involving the generation of human-animal brain chimera to have a mandatory component of assessing plausible changes in sentience.

Post-publication Peer Review with an Intention to Uncover Data/Result Irregularities and Potential Research Misconduct in Scientific Research: Vigilantism or Volunteerism?

Irregularities in data/results of scientific research might be spotted pre-publication by co-workers and reviewers, or post-publication by readers typically with vested interest. The latter might consist of fellow researchers in the same subject area who would naturally pay closer attention to a published paper. However, it is increasingly apparent that there are readers who interrogate papers in detail with a primary intention to identify potential problems with the work. Here, we consider post-publication peer review (PPPR) by individuals, or groups of individuals, who perform PPPRs with a perceptible intention to actively identify irregularities in published data/results and to expose potential research fraud or misconduct, or intentional misconduct exposing (IME)-PPPR. On one hand, such activities, when done anonymously or pseudonymously with no formal discourse, have been deemed as lacking in accountability, or perceived to incur some degree of maleficence, and have been labelled as vigilantism. On the other, these voluntary works have unravelled many instances of research misconduct and have helped to correct the literature. We explore the tangible benefits of IME-PPPR in detecting errors in published papers and from the perspectives of moral permissibility, research ethics, and the sociological perspective of science. We posit that the benefits of IME-PPPR activities that uncover clear evidence of misconduct, even when performed anonymously or pseudonymously, outweigh their perceived deficiencies. These activities contribute to a vigilant research culture that manifests the self-correcting nature of science, and are in line with the Mertonian norms of scientific ethos.

A Review of Scientific Ethics Issues Associated with the Recently Approved Drugs for Alzheimer's Disease.

Alzheimer's disease (AD), the devastating and most prevailing underlying cause for age-associated dementia, has no effective disease-modifying treatment. The last approved drug for the relief of AD symptoms was in 2003. The recent approval of sodium oligomannate (GV-971, 2019) in China and the human antibody aducanumab in the USA (ADUHELM, 2021) therefore represent significant breakthroughs, albeit ones that are fraught with controversy. Here, we explore potential scientific ethics issues associated with GV-971 and aducanumab's development and approval. While these issues may be belied by socioeconomic and political complexities in the heady business of commercial drug development, they are of fundamental importance to scientific integrity and ultimately, welfare of patients. We posit that the push for approval of both AD drugs based on incomplete research and unconvincing marginal effectiveness is ethically unsound. Regardless of how both these drugs shall perform in the market for the years to come, the scientific ethics issues and potentially questionable research practices should therefore be duly noted and lessons learned.

Moral obligations in conducting stem cell-based therapy trials for autism spectrum disorder.

Unregulated patient treatments and approved clinical trials have been conducted with haematopoietic stem cells and mesenchymal stem cells for children with autism spectrum disorder (ASD). While the former direct-to-consumer practice is usually considered rogue and should be legally constrained, regulated clinical trials could also be ethically questionable. Here, we outline principal objections against these trials as they are currently conducted. Notably, these often lack a clear rationale for how transplanted cells may confer a therapeutic benefit in ASD, and thus, have ill-defined therapeutic outcomes. We posit that ambiguous and unsubstantiated descriptions of outcome from such clinical trials may nonetheless appeal to the lay public as being based on authentic scientific findings. These may further fuel caregivers of patients with ASD to pursue unregulated direct-to-consumer treatments, thus exposing them to unnecessary risks. There is, therefore, a moral obligation on the part of those regulating and conducting clinical trials of stem cell-based therapeutic for ASD minors to incorporate clear therapeutic targets, scientific rigour and reporting accuracy in their work. Any further stem cell-based trials for ASD unsupported by significant preclinical advances and particularly sound scientific hypothesis and aims would be ethically indefensible.

RAB39B's role in membrane traffic, autophagy, and associated neuropathology.

Neuropathological disorders are increasingly associated with dysfunctions in neuronal membrane traffic and autophagy, with defects among members of the Rab family of small GTPases implicated. Mutations in the human Xq28 localized gene RAB39B have been associated with X-linked neurodevelopmental defects including macrocephaly, intellectual disability, autism spectrum disorder (ASD), as well as rare cases of early-onset Parkinson's disease (PD). Despite the finding that RAB39B regulates GluA2 trafficking and could thus influence synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor subunit composition, reasons for the wide-ranging neuropathological consequences associated with RAB39B defects have been unclear. Recent studies have now unraveled possible mechanisms underlying the neuropathological roles of this brain-enriched small GTPase. Studies in RAB39B knockout mice showed that RAB39B interacts with components of Class I phosphatidylinositol-3-kinase (PI3K) signaling. In its absence, the PI3K-AKT-mechanistic target of rapamycin signaling pathway in neural progenitor cells (NPCs) is hyperactivated, which promotes NPC proliferation, leading to macrocephaly and ASD. Pertaining to early-onset PD, a complex of C9orf72, Smith-Magenis syndrome chromosome region candidate 8 and WD repeat domain 41 that functions in autophagy has been identified as a guanine nucleotide exchange factor of RAB39B. Here, recent findings that have shed light on our mechanistic understanding of RAB39B's role in neurodevelopmental and neurodegenerative pathologies are reviewed. Caveats and unanswered questions are also discussed, and future perspectives outlined.

Glucose, glycolysis, and neurodegenerative diseases.

Prolonged survival of a typical postmitotic neuron hinges on a balance between multiple processes, among these are a sustenance of ATP production and protection against reactive oxygen species. In neuropathological conditions, mitochondrial defects often lead to both a drop in ATP levels, as well as increase reactive oxygen species production from inefficient electron transport processes and NADPH-oxidases activities. The former often resulted in the phenomenon of compensatory aerobic glycolysis. The latter stretches the capacity of the cell's redox buffering capacity, and may lead to damages of key enzymes involved in energy metabolism. Several recent reports have indicated that enhancing glucose availability and uptake, as well as increasing glycolytic flux via pharmacological or genetic manipulation of glycolytic enzymes, could be protective in animal models of several major neurodegenerative diseases, including Parkinson's disease, Huntington's disease, and Amyotrophic lateral sclerosis. Activation of canonical Wnt signaling, which improves disease symptoms in mouse models of Alzheimer's disease also appears to work via an elevation of glycolytic enzymes and enhance glucose metabolism. Here, I discuss these findings and the possible underlying mechanisms of how an increase in glucose uptake and glycolysis could be neuroprotective. Increased glycolytic production of ATP would help alleviate energy deficiency, and ATP's hydrotropic effect may enhance solubility and clearance of toxic aggregates prevalent in many neurodegenerative diseases. Furthermore, channeling of glucose into the Pentose Phosphate Pathway would increase the redox buffering capacity of the cell.

A Reflective Account of a Research Ethics Course for an Interdisciplinary Cohort of Graduate Students.

The graduate course in research ethics in the Graduate School for Integrative Sciences and Engineering at the National University of Singapore consists of a semester long mandatory course titled: "Research Ethics and Scientific Integrity." The course provides students with guiding principles for appropriate conduct in the professional and social settings of scientific research and in making morally weighted and ethically sound decisions when confronted with moral dilemmas. It seeks to enhance understanding and appreciation of the moral reasoning underpinning various rules and legislative constraints associated with research subjects and procedures. Further, students are trained to critically analyse cases and issues associated with scientific misconduct preparing them to act in a responsible and effective manner should they encounter such cases. The diverse background and training of the cohort also provide a unique setting and opportunity for student-initiated collaborative interdisciplinary learning. This article offers a reflective account of the course and some preliminary insights into learning outcomes.

Neuroprotection by glucose-6-phosphate dehydrogenase and the pentose phosphate pathway.

Glucose-6-phosphate dehydrogenase (G6PD), the rate limiting enzyme that channels glucose catabolism from glycolysis into the pentose phosphate pathway (PPP), is vital for the production of reduced nicotinamide adenine dinucleotide phosphate (NADPH) in cells. NADPH is in turn a substrate for glutathione reductase, which reduces oxidized glutathione disulfide to sulfhydryl glutathione. Best known for inherited deficiencies underlying acute hemolytic anemia due to elevated oxidative stress by food or medication, G6PD, and PPP activation have been associated with neuroprotection. Recent works have now provided more definitive evidence for G6PD's protective role in ischemic brain injury and strengthened its links to neurodegeneration. In Drosophila models, improved proteostasis and lifespan extension result from an increased PPP flux due to G6PD induction, which is phenocopied by transgenic overexpression of G6PD in neurons. Moderate transgenic expression of G6PD was also shown to improve healthspan in mouse. Here, the deciphered and implicated roles of G6PD and PPP in protection against brain injury, neurodegenerative diseases, and in healthspan/lifespan extensions are discussed together with an important caveat, namely NADPH oxidase (NOX) activity and the oxidative stress generated by the latter. Activation of G6PD with selective inhibition of NOX activity could be a viable neuroprotective strategy for brain injury, disease, and aging.

On Some Possible Ramifications of the "Microplastics in Fish" Case.

Cases of research misconduct in the ecological and environmental sciences appear to be relatively rare. A controversial paper published in Science in 2016 documenting the effects of microplastics on the feeding and innate behaviours of fish larvae has recently been retracted, with the authors found guilty of scientific misconduct. In addition to the expected fallout, such as individual and institutional reputational damage from a research misconduct finding, this case has two possibly wider-ranging ramifications. Firstly, there may be a presumptive notion that a strong negative effect could be more successfully published than a neutral effect. This presumption would belie the true stringency and rigor of research adopted by workers in the field. Secondly, the case may have a negative impact on the public's perception of and trust in legitimate and good science that addresses critical environmental issues, such as anthropogenic climate change.

Sec16 in conventional and unconventional exocytosis: Working at the interface of membrane traffic and secretory autophagy?

Sec16 is classically perceived to be a scaffolding protein localized to the transitional endoplasmic reticulum (tER) or the ER exit sites (ERES), and has a conserved function in facilitating coat protein II (COPII) complex-mediated ER exit. Recent findings have, however, pointed toward a role for Sec16 in unconventional exocytosis of certain membrane proteins, such as the Cystic fibrosis transmembrane conductance regulator (CFTR) in mammalian cells, and possibly also α-integrin in certain contexts of Drosophila development. In this regard, Sec16 interacts with components of a recently deciphered pathway of stress-induced unconventional exocytosis, which is dependent on the tether protein Golgi reassembly stacking proteins (GRASPs) and the autophagy pathway. Intriguingly, Sec16 also appears to be post-translationally modified by autophagy-related signaling processes. Sec16 is known to be phosphorylated by the atypical extracellular signal regulated kinase 7 (Erk7) upon serum and amino acid starvation, both represent conditions that trigger autophagy. Recent work has also shown that Sec16 is phosphorylated, and thus regulated by the prominent autophagy-initiating Unc-51-like autophagy activating kinase 1 (Ulk1), as well as another autophagy modulator Leucine-rich repeat kinase 2 (Lrrk2). The picture emerging from Sec16's network of physical and functional interactors allows the speculation that Sec16 is situated (and may in yet undefined ways function) at the interface between COPII-mediated exocytosis of conventional vesicular traffic and the GRASP/autophagy-dependent mode of unconventional exocytosis.

Rabs, Membrane Dynamics, and Parkinson's Disease.

Genes encoding cellular membrane trafficking components, namely RAB7L1 and RAB39B, are more recently recognized factors associated with Parkinson's disease (PD). Encoded by a gene within the PARK16 locus, RAB7L1 interacts with Leucine-rich repeat kinase 2 (LRRK2) to act in intracellular transport processes that are likely important for neuronal survival and function. LRRK2 also directly phosphorylates a number of other Rab proteins. On the other hand, nonsense and missense mutations of the X-chromosome localized RAB39B were shown to underlie X-linked intellectual disability (ID) in male patients with early-onset PD. The cellular or neuronal functions of RAB39B are not yet known with certainty, but it has recently been shown to play a role in glutamate receptor trafficking. Importantly, RAB39B is also functionally connected to components for autophagy regulation, which affects α-synuclein processing and clearance. In this review, we discuss the association of Rabs with PD pathology, and potential etiological mechanisms whereby defects or deficiencies in certain Rab proteins could lead to PD susceptibility. J. Cell. Physiol. 232: 1626-1633, 2017. © 2016 Wiley Periodicals, Inc.

A role for Rab23 in the trafficking of Kif17 to the primary cilium.

The small GTPase Rab23 is an antagonist of sonic hedgehog (Shh) signaling during mouse development. Given that modulation of Shh signaling depends on the normal functioning of the primary cilium, and overexpression of Evi5L, a putative Rab23 GTPase-activating protein (GAP), leads to reduced ciliogenesis, Rab23 could have a role at the primary cilium. Here, we found that wild-type Rab23 and the constitutively active Rab23 Q68L mutant were enriched at the primary cilium. Therefore, we tested the role of Rab23 in the ciliary targeting of known cargoes and found that ciliary localization of the kinesin-2 motor protein Kif17 was disrupted in Rab23-depleted cells. Co-immunoprecipitation and affinity-binding studies revealed that Rab23 exists in a complex with Kif17 and importin ß2 (the putative Kif17 ciliary import carrier), implying that Kif17 needs to bind to regulatory proteins like Rab23 for its ciliary transport. Although a ciliary-cytoplasmic gradient of nuclear Ran is necessary to regulate the ciliary transport of Kif17, Rab23 and Ran appear to have differing roles in regulating the ciliary entry of Kif17. Our findings have uncovered a hitherto unknown effector of Rab23 and demonstrate how Rab23 could mediate the transport of Kif17 to the primary cilium.

Sirtuins as modifiers of Parkinson's disease pathology.

Parkinson's disease (PD) is the most common movement disorder associated with the elderly which, other than symptomatic therapies, has no effective treatment or preventive measures. Sirtuins and their pharmacological activators/inhibitors have been associated with a range of neuroprotective effects, and a large body of work on sirtuins' influence on PD pathology has accumulated over the past decade. Here, evidence for sirtuins' activities as modifiers of PD pathology and how the mammalian sirtuin paralogues may have conflicting impacts on PD pathogenesis and disease progression is reviewed. The possible cellular and molecular mechanisms underlying sirtuin activities in PD are discussed in the light of current knowledge with reference to autophagy, mitochondrial homeostasis, and microtubule dynamics. © 2016 Wiley Periodicals, Inc.

Intracellular Uropathogenic E. coli Exploits Host Rab35 for Iron Acquisition and Survival within Urinary Bladder Cells.

Recurrent urinary tract infections (UTIs) caused by uropathogenic E. coli (UPEC) are common and morbid infections with limited therapeutic options. Previous studies have demonstrated that persistent intracellular infection of bladder epithelial cells (BEC) by UPEC contributes to recurrent UTI in mouse models of infection. However, the mechanisms employed by UPEC to survive within BEC are incompletely understood. In this study we aimed to understand the role of host vesicular trafficking proteins in the intracellular survival of UPEC. Using a cell culture model of intracellular UPEC infection, we found that the small GTPase Rab35 facilitates UPEC survival in UPEC-containing vacuoles (UCV) within BEC. Rab35 plays a role in endosomal recycling of transferrin receptor (TfR), the key protein responsible for transferrin-mediated cellular iron uptake. UPEC enhance the expression of both Rab35 and TfR and recruit these proteins to the UCV, thereby supplying UPEC with the essential nutrient iron. Accordingly, Rab35 or TfR depleted cells showed significantly lower intracellular iron levels and reduced ability to support UPEC survival. In the absence of Rab35, UPEC are preferentially trafficked to degradative lysosomes and killed. Furthermore, in an in vivo murine model of persistent intracellular infection, Rab35 also colocalizes with intracellular UPEC. We propose a model in which UPEC subverts two different vesicular trafficking pathways (endosomal recycling and degradative lysosomal fusion) by modulating Rab35, thereby simultaneously enhancing iron acquisition and avoiding lysosomal degradation of the UCV within bladder epithelial cells. Our findings reveal a novel survival mechanism of intracellular UPEC and suggest a potential avenue for therapeutic intervention against recurrent UTI.

Could Sirtuin Activities Modify ALS Onset and Progression?

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with a complex etiology. Sirtuins have been implicated as disease-modifying factors in several neurological disorders, and in the past decade, attempts have been made to check if manipulating Sirtuin activities and levels could confer benefit in terms of neuroprotection and survival in ALS models. The efforts have largely focused on mutant SOD1, and while limited in scope, the results were largely positive. Here, the body of work linking Sirtuins with ALS is reviewed, with discussions on how Sirtuins and their activities may impact on the major etiological mechanisms of ALS. Moving forward, it is important that the potentially beneficial effect of Sirtuins in ALS disease onset and progression are assessed in ALS models with TDP-43, FUS, and C9orf72 mutations.

K+-Cl- co-transporter 2 (KCC2) - a membrane trafficking perspective.

K+-Cl- co-transporter 2 (KCC2/SLC12A5) is a neuronal specific cation chloride co-transporter which is active under isotonic conditions, and thus a key regulator of intracellular Cl- levels. It also has an ion transporter-independent structural role in modulating the maturation and regulation of excitatory glutamatergic synapses. KCC2 levels are developmentally regulated, and a postnatal upregulation of KCC2 generates a low intracellular chloride concentration that allows the neurotransmitters γ-aminobutyric acid (GABA) and glycine to exert inhibitory neurotransmission through its Cl- permeating channel. Functional expression of KCC2 at the neuronal cell surface is necessary for its activity, and impairment in KCC2 cell surface transport and/or internalization may underlie a range of neuropathological conditions. Although recent advances have shed light on a range of cellular mechanisms regulating KCC2 activity, little is known about its membrane trafficking itinerary and regulatory proteins. In this review, known membrane trafficking signals, pathways and mechanisms pertaining to KCC2's functional surface expression are discussed.

Rab, Arf, and Arl-Regulated Membrane Traffic in Cortical Neuron Migration.

The migration of projection neurons from its birthplace in the subventricular zone to their final destination in the cortical plate is a complex process that requires a series of highly coordinated cellular events. Amongst the key factors involved in the processes are modulators of cytoskeletal dynamics, as well as cellular membrane traffic. Members of the small GTPases family responsible for the latter process, the Rabs and Arfs, have been recently implicated in cortical neuron migration. Rab5 and Rab11, which are key modulators of endocytosis and endocytic recycling respectively, ensure proper surface expression and distribution of N-cadherin, a key adhesion protein that tethers migrating neurons to the radial glia fiber tracts during pia-directed migration. Rab7, which is associated with lysosomal biogenesis and function, is important for the final step of terminal translocation when N-cadherin is downregulated by lysosomal degradation. Arf6 activity, which is known to be important in neuronal processes outgrowth, may negatively impact the multipolar-bipolar transition of cortical neurons undergoing radial migration, but the downstream effector of Arf6 in this regard is not yet known. In addition to the above, members of the Arl family which have been recently shown to be important in radial glia scaffold formation, would also be important for cortical neuron migration. In this short review, we discuss recent advances in our understanding of the importance of membrane traffic regulated by the Rab, Arf, and Arl family members in cortical neuron migration.