Publications

ABSTRACT

Mitophagy, the cellular process of selectively eliminating damaged mitochondria, plays a crucial role in main­taining metabolic balance and preventing insulin resistance, both key factors in type 2 diabetes mellitus (T2DM) development. When mitophagy malfimctions in diabetic neuropathy, it triggers a cascade of metabolic disrup­tions, including reduced energy production, increased oxidative stress, and cell death, ultimately leading to various complications. Thus, targeting mitophagy to enhance the process may have emerged as a promising therapeutic strategy for T2DM and its complications. Notably, plant-derived compounds with 􀀜-cell protective and mitophagy-stimulating properties offer potential as novel therapeutic agents. This review highlights the intricate mechanisms linking mitophagy dysfunction to T2DM and its complications, particularly neuropathy, elucidating potential therapeutic interventions for this debilitating disease.

Full article:https://doi.org/10.1016/j.phrs.2024.107394

ABSTRACT

Macroautophagy/autophagy is primarily accountable for the degradation of damaged organelles and toxic macromolecules in the cells. Regarding the essential function of autophagy for preserving cellular homeostasis, changes in, or dysfunction of, autophagy flux can lead to disease development. In the current paper, the complicated function of autophagy in aging-associated pathologies and cancer is evaluated, highlighting the underlying molecular mechanisms that can affect longevity and disease pathogenesis. As a natural biological process, a reduction in autophagy is observed with aging, resulting in an accumulation of cell damage and the development of different diseases, including neurological disorders, cardiovascular diseases, and cancer. The MTOR, AMPK, and ATG proteins demonstrate changes during aging, and they are promising therapeutic targets. Insulin/lGFl, TOR, PKA, AKT/PKB, caloric restriction and mitochondrial respiration are vital for lifespan.

Full article:https://doi.org/10.1016/j.arr.2024.102428

Mechanisms of sensitivity and resistance to CDK4/CDK6 inhibitors in hormone receptor-positive breast cancer treatment

Antonino Glaviano, Seth A. Wander, Richard D. Baird, Kenneth C.-H. Yap, Hiu Yan Lam, Masakazu Toi, Daniela Carbone, Birgit Geoerger, Violeta Serra, Robert H. Jones, Joanne Ngeow, Eneda Toska, Justin Stebbing, Karen Crasta, Richard S. Finn, Patrizia Diana, Karla Vuina, Robertus A.M. de Bruin, Uttam Surana, Aditya Bardia, Alan Prem Kumar

Cell cycle dysregulation is a hallmark of cancer that promotes eccessive cell division. Cyclin-dependent kinase 4 (CDK4) and cyclin-dependent kinase 6 (CDK6) are key molecules in the G1-to-S phase cell cycle transition and are crucial for the onset, survival, and progression of breast cancer (BC). Small-molecule CDK4/CDK6 inhibitors (CDK4/6i) block phosphorylation of tumor suppressor Rb and thus restrain susceptible BC cells in G1 phase. Three CDK4/6i are approved for the first-line treatment of patients with advanced/metastatic hormone receptor-positive (HR⁺)/human epidermal growth factor receptor 2-negative (HER2^–) BC in combination with endocrine therapy (ET). Though this has improved the clinical outcomes for survival of BC patients, there is no established standard next-line treatment to tackle drug resistance. Recent studies suggest that CDK4/6i can modulate other distinct effects in both BC and breast stromal compartments, which may provide new insights into aspects of their clinical activity. This review describes the biochemistry of the CDK4/6-Rb-E2F pathway in HR⁺ BC, then discusses how CDK4/6i can trigger other effects in BC/breast stromal compartments, and finally outlines the mechanisms of CDK4/6i resistance that have emerged in recent preclinical studies and clinical cohorts, emphasizing the impact of these findings on novel therapeutic opportunities in BC.

Full article: https://www.sciencedirect.com/science/article/pii/S136876462400061X?via%3Dihub

Insights from multi-omic modeling of neurodegeneration in xeroderma pigmentosum using an induced pluripotent stem cell system
Cherif Badja, Sophie Momen, Gene Ching Chiek Koh, Soraya Boushaki, Theodoros I. Roumeliotis, Zuza Kozik, Ian Jones, Vicky Bousgouni, Jo~ao M.L. Dias, Marios G. Krokidis, Jamie Young, Hongwei Chen, Ming Yang, France Docquier, Yasin Memari, Lorea Valcarcel-Zimenez, Komal Gupta, Li Ren Kong, Heather Fawcett, Florian Robert, Salome Zhao, Andrea Degasperi, Yogesh Kumar, Helen Davies, Rebecca Harris, Christian Frezza, Chryssostomos Chatgilialoglu, Robert Sarkany, Alan Lehmann, Chris Bakal, Jyoti Choudhary, Hiva Fassihi, and Serena Nik-Zainal

Xeroderma pigmentosum(XP) is caused by defective nucleotide excision repair of DNA damage. This results in hypersensitivity to ultraviolet light and increased skin cancer risk, as sunlight-induced photoproducts remain unrepaired. However, many XP patients also display early-onset neurodegeneration, which leads to premature death. The mechanism of neurodegeneration is unknown. Here, we investigate XP neurodegeneration using pluripotent stemcellsderivedfromXPpatients andhealthy relatives, performingfunctional multi-omicsonsamples duringneuronaldifferentiation.We showsubstantially increasedlevels of 50,8-cyclopurineand8-oxopurine in XPneuronalDNAsecondary tomarked oxidative stress. Furthermore,we find that the endoplasmic reticulum stress response is upregulated and reversal of the mutant genotype is associatedwith phenotypic rescue. Critically, XP neurons exhibit inappropriate downregulation of the protein clearance ubiquitin-proteasome system (UPS). Chemical enhancement of UPS activity in XP neuronal models improves phenotypes, albeit inadequately. Although more work is required, this study presents insights with intervention potential.

Full article: https://www.cell.com/cell-reports/fulltext/S2211-1247(24)00571-0

Direct vagus nerve stimulation: A new tool to control allergic airway inflammation through α7 nicotinic acetylcholine receptor
Caroline Sévoz-Couche, Wupeng Liao, Hazel Y. C. Foo, Isabelle Bonne, Thong Beng Lu, Caris Tan Qi Hui, Wendy Yen Xian Peh, Shi-Cheng Yen, W. S. Fred Wong

Background and Purpose: Asthma is characterized by airway inflammation, mucus hypersecretion, and airway hyperresponsiveness. The use of nicotinic agents to mimic the cholinergic anti-inflammatory pathway (CAP) controls experimental asthma. Yet, the effects of vagus nerve stimulation (VNS)-induced CAP on allergic inflammation remain unknown.

Experimental Approach: BALB/c mice were sensitized and challenged with house dust mite (HDM) extract and treated with active VNS (5 Hz, 0.5 ms, 0.05–1 mA). Bronchoalveolar lavage (BAL) fluid was assessed for total and differential cell counts and cytokine levels. Lungs were examined by histopathology and electron microscopy.

Key Results: In the HDM mouse asthma model, VNS at intensities equal to or above 0.1 mA (VNS 0.1) but not sham VNS reduced BAL fluid differential cell counts and alveolar macrophages expressing α7 nicotinic receptors (α7nAChR), goblet cell hyperplasia, and collagen deposition. Besides, VNS 0.1 also abated HDM-induced elevation of type 2 cytokines IL-4 and IL-5 and was found to block the phosphorylation of transcription factor STAT6 and expression level of IRF4 in total lung lysates. Finally, VNS 0.1 abrogated methacholine-induced hyperresponsiveness in asthma mice. Prior administration of α-bungarotoxin, a specific inhibitor of α7nAChR, but not propranolol, a specific inhibitor of β2-adrenoceptors, abolished the therapeutic effects of
VNS 0.1.

Conclusion and Implications: Our data revealed the protective effects of VNS on various clinical features in allergic airway inflammation model. VNS, a clinically approved therapy for depression and epilepsy, appears to be a promising new strategy for controlling allergic asthma.

A glycolytic metabolite bypasses ‘‘two-hit’’ tumor suppression by BRCA2
Li Ren Kong, Komal Gupta, Andy Jialun Wu, David Perera, Roland lvanyi-Nagy, Syed Moiz Ahmed, Tuan Zea Tan, Shawn Lu-Wen Tan, Alessandra Fuddin, Elayanambi Sundaramoorthy, Grace Shiqing Goh, Regina Tong Xin Wong, Ana S.H. Costa, Callum Oddy, Hannan Wong, C. Pawan K. Patro, Yun Suen Kho,
Xiao Zi Huang, Joan Choo, Mona Shehata, Soo Chin Lee, Boon Cher Goh, Christian Frezza, Jason J. Pitt, and Ashok R. Venkitaraman

Knudson’s “two-hit” paradigm posits that carcinogenesis requires inactivation of both copies of an autosomal tumor suppressor gene. Here, we report that the glycolytic metabolite methylglyoxal (MGO) transiently bypasses Knudson’s paradigm by inactivating the breast cancer suppressor protein BRCA2 to elicit a cancer-associated, mutational single-base substitution (SBS) signature in nonmalignant mammary cells or patient-derived organoids. Germline monoallelic BRCA2 mutations predispose to these changes. An analogous SBS signature, again without biallelic BRCA2 inactivation, accompanies MGO accumulation and DNA dam­ age in Kras-driven, Brca2-mutant murine pancreatic cancers and human breast cancers. MGO triggers BRCA2 proteolysis, temporarily disabling BRCA2’s tumor suppressive functions in DNA repair and replication, causing functional haploinsufficiency. Intermittent MGO exposure incites episodic SBS mutations without permanent BRCA2 inactivation. Thus, a metabolic mechanism wherein MGO-induced BRCA2 haploinsufficiency transiently bypasses Knudson’s two-hit requirement could link glycolysis activation by onco­ genes, metabolic disorders, or dietary challenges to mutational signatures implicated in cancer evolution.

Link to full article: https://pubmed.ncbi.nlm.nih.gov/38417710/

Blood-based biomarkers of cerebral small vessel disease
Liu-Yun Wu, Yuek Ling Chai, Irwin K. Cheah, Rachel S.L. Chia Saima Hilal, Thiruma V. Arumugam, Christopher P. Chen, Mitchell K.P. Lai

Age-associated cerebral small vessel disease (CSVD) represents a clinically heterogenous condition, arising from diverse microvascular mechanisms. These lead to chronic cerebrovascular dysfunction and carry a substantial risk of subsequent stroke and vascular cognitive impairment in aging populations. Owing to advances in neu-roimaging, in vivo visualization of cerebral vasculature abnormities and detection of CSVD, including lacunes, microinfarcts, microbleeds and white matter lesions, is now possible, but remains a resource-, skills- and time- intensive approach. As a result, there has been a recent proliferation of blood-based biomarker studies for CSVD aimed at developing accessible screening tools for early detection and risk stratification. However, a good understanding of the pathophysiological processes underpinning CSVD is needed to identify and assess clinically useful biomarkers. Here, we provide an overview of processes associated with CSVD pathogenesis, including endothelial injury and dysfunction, neuroinflammation, oxidative stress, perivascular neuronal damage as well as cardiovascular dysfunction. Then, we review clinical studies of the key biomolecules involved in the afore-mentioned processes. Lastly, we outline future trends and directions for CSVD biomarker discovery and clinical validation.

Link to full article: https://pubmed.ncbi.nlm.nih.gov/38417710/

Tharindunee Jayakody, Asuka Inoue, Srinivasaraghavan Kannan, Gaku Nakamura, Kouki Kawakami, Krishan Mendis, Thanh-Binh Nguyen, Jianguo Li, Deron R. Herr, Chandra S. Verma, Gavin S. Dawe

The neuropeptide relaxin-3 is composed of an A chain and a B chain held together by disulfide bonds, and it modu- lates functions such as anxiety and food intake by binding to and activating its cognate receptor RXFP3, mainly through the B chain. Biased ligands of RXFP3 would help to determine the molecular mechanisms underlying the

activation of G proteins and β-arrestins downstream of RXFP3 that lead to such diverse functions. We showed that the i, i+4 stapled relaxin-3 B chains, 14s18 and d(1-7)14s18, were Gα_i/o-biased agonists of RXFP3. These peptides did not induce recruitment of β-arrestin1/2 to RXFP3 by GPCR kinases (GRKs), in contrast to relaxin-3, which enabled the GRK2/3-mediated recruitment of β-arrestin1/2 to RXFP3. Relaxin-3 and the previously reported peptide 4 (an i, i+4 stapled relaxin-3 B chain) did not exhibit biased signaling. The staple linker of peptide 4 and parts of both the A chain and B chain of relaxin-3 interacted with extracellular loop 3 (ECL3) of RXFP3, moving it away from the

binding pocket, suggesting that unbiased ligands promote a more open conformation of RXFP3. These findings highlight roles for the A chain and the N-terminal residues of the B chain of relaxin-3 in inducing conformational changes in RXFP3, which will help in designing selective biased ligands with improved therapeutic efficacy.

Image credit: Office of the Deputy President (Research and Technology)

Twelve tips to leverage AI for efficient and effective medical question generation: A guide for educators using Chat GPT

Inthrani Raja Indran , Priya Paramanathan, Neelima Gupta and Nurulhuda Mustafa

Department of Pharmacology, National University of Singapore, Yong Loo Lin School of Medicine, Singapore, Singapore

Abstract

Background: Crafting quality assessment questions in medical education is a crucial yet time-consuming, expertise-driven undertaking that calls for innovative solutions. Large language models (LLMs), such as ChatGPT (Chat Generative Pre-Trained Transformer), present a promising yet underexplored avenue for such innovations.

Aims: This study explores the utility of ChatGPT to generate diverse, high-quality medical questions, focusing on multiple-choice questions (MCQs) as an illustrative example, to increase educator’s productivity and enable self-directed learning for students.

Description: Leveraging 12 strategies, we demonstrate how ChatGPT can be effectively used to generate assessment questions aligned with Bloom’s taxonomy and core knowledge domains while promoting best practices in assessment design.

Conclusion: Integrating LLM tools like ChatGPT into generating medical assessment questions like MCQs augments but does not replace human expertise. With continual instruction refinement, AI can produce high-standard questions. Yet, the onus of ensuring ultimate quality and accuracy remains with subject matter experts, affirming the irreplaceable value of human involvement in the artificial intelligence-driven education paradigm.

MEDICAL TEACHER
https://doi.org/10.1080/0142159X.2023.2294703

SHP2 inhibitors maintain TGFβ signalling through SMURF2 inhibition

Xianning Lai, Sarah Kit Leng Lui, Hiu Yan Lam, Yuta Adachi, Wen Jing Sim, Natali Vasilevski, Nicola J. Armstrong, Stephanie Claire Bridgeman,

Nathan Michael Main, Tuan Zea Tan, Janina E. E. Tirnitz-Parker, Jean Paul Thiery, Hiromichi Ebi, Alan Prem Kumar, and Pieter Johan Adam Eichhorn

Abstract

Despite the promising antitumor activity of SHP2 inhibitors in RAS-dependent tumours, overall responses have been limited by
their narrow therapeutic window. Like with all MAPK pathway inhibitors, this is likely the result of compensatory pathway activation
mechanisms. However, the underlying mechanisms of resistance to SHP2 inhibition remain unknown. The E3 ligase SMURF2 limits
TGFβ activity by ubiquitinating and targeting the TGFβ receptor for proteosome degradation. Using a functional RNAi screen
targeting all known phosphatases, we identify that the tyrosine phosphatase SHP2 is a critical regulator of TGFβ activity. Specifically,
SHP2 dephosphorylates two key residues on SMURF2, resulting in activation of the enzyme. Conversely, SHP2 depletion maintains
SMURF2 in an inactive state, resulting in the maintenance of TGFβ activity. Furthermore, we demonstrate that depleting SHP2 has
significant implications on TGFβ-mediated migration, senescence, and cell survival. These effects can be overcome through the use
of TGFβ-targeted therapies. Consequently, our findings provide a rationale for combining SHP2 and TGFβ inhibitors to enhance
tumour responses leading to improved patient outcomes.

npj Precision Oncology (2023)7:136 ; https://doi.org/10.1038/s41698-023-00486-6