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result(s) for
"Rehan, Shahid"
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Rapamycin-inspired macrocycles with new target specificity
by
Schiene-Fischer, Cordelia
,
Bhat, Shridhar
,
Ullman, Brett R.
in
631/92/2132
,
639/638/309/507
,
639/638/92/2132
2019
Rapamycin and FK506 are macrocyclic natural products with an extraordinary mode of action, in which they form binary complexes with FK506-binding protein (FKBP) through a shared FKBP-binding domain before forming ternary complexes with their respective targets, mechanistic target of rapamycin (mTOR) and calcineurin, respectively. Inspired by this, we sought to build a rapamycin-like macromolecule library to target new cellular proteins by replacing the effector domain of rapamycin with a combinatorial library of oligopeptides. We developed a robust macrocyclization method using ring-closing metathesis and synthesized a 45,000-compound library of hybrid macrocycles (named rapafucins) using optimized FKBP-binding domains. Screening of the rapafucin library in human cells led to the discovery of rapadocin, an inhibitor of nucleoside uptake. Rapadocin is a potent, isoform-specific and FKBP-dependent inhibitor of the equilibrative nucleoside transporter 1 and is efficacious in an animal model of kidney ischaemia reperfusion injury. Together, these results demonstrate that rapafucins are a new class of chemical probes and drug leads that can expand the repertoire of protein targets well beyond mTOR and calcineurin.
Rapamycin and FK506 are macrocycles that contain an FKBP-binding domain and an effector domain responsible for interacting with their respective targets, mTOR and calcineurin. Now, a 45,000-compound macrocycle library has been synthesized by fusing oligopeptides with synthetic FKBP-binding domains. Screening and subsequent optimization yielded a highly potent FKBP-dependent inhibitor of hENT1.
Journal Article
Signal peptide mimicry primes Sec61 for client-selective inhibition
2023
Preventing the biogenesis of disease-relevant proteins is an attractive therapeutic strategy, but attempts to target essential protein biogenesis factors have been hampered by excessive toxicity. Here we describe KZR-8445, a cyclic depsipeptide that targets the Sec61 translocon and selectively disrupts secretory and membrane protein biogenesis in a signal peptide-dependent manner. KZR-8445 potently inhibits the secretion of pro-inflammatory cytokines in primary immune cells and is highly efficacious in a mouse model of rheumatoid arthritis. A cryogenic electron microscopy structure reveals that KZR-8445 occupies the fully opened Se61 lateral gate and blocks access to the lumenal plug domain. KZR-8445 binding stabilizes the lateral gate helices in a manner that traps select signal peptides in the Sec61 channel and prevents their movement into the lipid bilayer. Our results establish a framework for the structure-guided discovery of novel therapeutics that selectively modulate Sec61-mediated protein biogenesis.
A selective inhibitor of Sec61 blocks protein entry into the secretory pathway and has therapeutic efficacy in rheumatoid arthritis. A cryo-EM structure of the inhibited Sec61 provides a model for client-selective protein translocation inhibition.
Journal Article
Molecular view of ER membrane remodeling by the Sec61/TRAP translocon
by
Javanainen, Matti
,
Karki, Sudeep
,
Tranter, Dale
in
Biochemistry
,
Endoplasmic reticulum
,
Glycosylation
2022
Protein translocation across the endoplasmic reticulum (ER) membrane is an essential initial step in protein entry into the secretory pathway. The conserved Sec61 protein translocon facilitates polypeptide translocation and coordinates cotranslational polypeptide processing events. In cells, the majority of Sec61 is stably associated with a heterotetrameric membrane protein complex, the translocon associated protein complex (TRAP), yet the mechanism by which TRAP assists in polypeptide translocation or cotranslational modifications such as N-glycosylation remains unknown. Here, we demonstrate the structure of the core Sec61/TRAP complex bound to a mammalian ribosome by Cryo-EM. The interactions with the ribosome anchor the Sec61/TRAP complex in a conformation that renders the ER membrane locally thinner by significantly curving its the lumenal leaflet. We propose a model for how TRAP stabilizes the ribosome exit tunnel to assist nascent polypeptide insertion through Sec61 and provides a ratcheting mechanism into the ER lumen by direct polypeptide interactions. Competing Interest Statement The authors have declared no competing interest.
Signal peptide mimicry primes Sec61 for client-selective inhibition
2022
Preventing the biogenesis of disease-relevant proteins is an attractive therapeutic strategy, but attempts to target essential protein biogenesis factors have been hampered by excessive toxicity. Here, we describe KZR-8445, a cyclic depsipeptide that targets the Sec61 translocon and selectively disrupts secretory and membrane protein biogenesis in a signal peptide-dependent manner. KZR-8445 potently inhibits the secretion of proinflammatory cytokines in primary immune cells and is highly efficacious in a mouse model of rheumatoid arthritis. A cryo-EM structure reveals that KZR-8445 occupies the fully opened Se61 lateral gate and blocks access to the lumenal plug domain. KZR-8445 binding stabilizes the lateral gate helices in a manner that traps select signal peptides in the Sec61 channel and prevents their movement into the lipid bilayer. Our results establish a framework for the structure-guided discovery of novel therapeutics that selectively modulate Sec61-mediated protein biogenesis.
Nanoenzymes: A Radiant Hope for the Early Diagnosis and Effective Treatment of Breast and Ovarian Cancers
by
Asif, Roha
,
Kanwal, Qudsia
,
Shahid, Samiah
in
Animals
,
Breast cancer
,
Breast Neoplasms - therapy
2024
Breast and ovarian cancers, despite having chemotherapy and surgical treatment, still have the lowest survival rate. Experimental stages using nanoenzymes/nanozymes for ovarian cancer diagnosis and treatment are being carried out, and correspondingly the current treatment approaches to treat breast cancer have a lot of adverse side effects, which is the reason why researchers and scientists are looking for new strategies with less side effects. Nanoenzymes have intrinsic enzyme-like activities and can reduce the shortcomings of naturally occurring enzymes due to the ease of storage, high stability, less expensive, and enhanced efficiency. In this review, we have discussed various ways in which nanoenzymes are being used to diagnose and treat breast and ovarian cancer. For breast cancer, nanoenzymes and their multi-enzymatic properties can control the level of reactive oxygen species (ROS) in cells or tissues, for example, oxidase (OXD) and peroxidase (POD) activity can be used to generate ROS, while catalase (CAT) or superoxide dismutase (SOD) activity can scavenge ROS. In the case of ovarian cancer, most commonly nanoceria is being investigated, and also when folic acid is combined with nanoceria there are additional advantages like inhibition of beta galactosidase. Nanocarriers are also used to deliver small interfering RNA that are effective in cancer treatment. Studies have shown that iron oxide nanoparticles are actively being used for drug delivery, similarly ferritin carriers are used for the delivery of nanozymes. Hypoxia is a major factor in ovarian cancer, therefore MnO
-based nanozymes are being used as a therapy. For cancer diagnosis and screening, nanozymes are being used in sonodynamic cancer therapy for cancer diagnosis and screening, whereas biomedical imaging and folic acid gold particles are also being used for image guided treatments. Nanozyme biosensors have been developed to detect ovarian cancer. This review article summarizes a detailed insight into breast and ovarian cancers in light of nanozymes-based diagnostic and therapeutic approaches.
Journal Article
Relationship between prostate-specific antigen, alkaline phosphatase levels, and time-to-tumor shrinkage: understanding the progression of prostate cancer in a longitudinal study
2024
Background
This study delves into the complex interplay among prostate-specific antigen, alkaline phosphatase, and the temporal dynamics of tumor shrinkage in prostate cancer. By investigating the longitudinal trajectories and time-to-prostate cancer tumor shrinkage, we aim to untangle the intricate patterns of these biomarkers. This understanding is pivotal for gaining profound insights into the multifaceted aspects of prostate cancer progression. The joint model approach serves as a comprehensive framework, facilitating the elucidation of intricate interactions among these pivotal elements within the context of prostate cancer .
Methods
A new joint model under a shared parameters strategy is proposed for mixed bivariate longitudinal biomarkers and event time data, for obtaining accurate estimates in the presence of missing covariate data. The primary innovation of our model resides in its effective management of covariates with missing observations. Built upon established frameworks, our joint model extends its capabilities by integrating mixed longitudinal responses and accounting for missingness in covariates, thus confronting this particular challenge. We posit that these enhancements bolster the model’s utility and dependability in real-world contexts characterized by prevalent missing data. The main objective of this research is to provide a model-based approach to get full information from prostate cancer data collected with patients’ baseline characteristics (
Age
, body mass index (
BMI
),
GleasonScore
,
Grade
, and
Drug
) and two longitudinal endogenous covariates (
Platelets
and
Bilirubin
).
Results
The results reveal a clear association between prostate-specific antigen and alkaline phosphatase biomarkers in the context of time-to-prostate cancer tumor shrinkage. This underscores the interconnected dynamics of these key indicators in gauging disease progression.
Conclusions
The analysis of the prostate cancer dataset, incorporating a joint evaluation of mixed longitudinal prostate-specific antigen and alkaline phosphatase biomarkers alongside tumor status, has provided valuable insights into disease progression. The results demonstrate the effectiveness of the proposed joint model, as evidenced by accurate estimates. The shared variables associated with both longitudinal biomarkers and event times consistently deviate from zero, highlighting the robustness and reliability of the model in capturing the complex dynamics of prostate cancer progression. This approach holds promise for enhancing our understanding and predictive capabilities in the clinical assessment of prostate cancer.
Journal Article
Effects of informal learner handover in clinical dental education
2023
Background
It is currently under discussion whether Learner Handovers (LH) are beneficial, disadvantageous, or useful in Health Professions Education. Research has not been conducted to determine the extent of existing informal learner handover (ILH) through faculty discussions. In addition to providing stakeholders with added context, examining the nature of ILH may also provide insight into the bias associated with Learner Handover.
Methods
Transcripts from a series of semi-structured Focus Group Discussions (FGDs) and interviews (from January to March 2022) were iteratively reviewed to identify relevant patterns and correlations. The study involved the voluntary participation of 16 active clinical dental faculty members with a variety of designations. We did not discard any opinions.
Results
It was found that ILH had a mild impact on students' training. ILH effects can be categorized into four key areas: (1) faculty behavior with students, (2) faculty expectations from students, 3) teaching approach, and 4) faculty feedback practices. Furthermore, five additional factors were identified as having a greater influence on ILH practices.
Conclusions
In clinical dental training, ILH has a minor effect on faculty-student interactions. Faculty perceptions and ILH are strongly influenced by other factors contributing to the student's 'academic reputation. As a result, student-faculty interactions are never free of prior influences, so stakeholders need to take them into consideration when creating a formal LH.
Journal Article
A Novel False Measurement Data Detection Mechanism for Smart Grids
2023
With the growing cyber-infrastructure of smart grids, the threat of cyber-attacks has intensified, posing an increased risk of compromised communication links. Of particular concern is the false data injection (FDI) attack, which has emerged as a highly dangerous cyber-attack targeting smart grids. This paper addresses the limitations of the variable dummy value model proposed in the authors previous work and presents a novel defense methodology called the nonlinear function-based variable dummy value model for the AC power flow network. The proposed model is evaluated using the IEEE 14-bus test system, demonstrating its effectiveness in detecting FDI attacks. It has been shown that previous detection techniques are unable to detect FDI attacks, whereas the proposed method is shown to be successful in the detection of such attacks, guaranteeing the security of the smart grid’s measurement infrastructure.
Journal Article
ZOMEC via the p-Akt/Nrf2 Pathway Restored PTZ-Induced Oxidative Stress-Mediated Memory Dysfunction in Mouse Model
by
Shah, Shahid Ali
,
Ijaz, Musarrat
,
Bibi, Nousheen
in
AKT protein
,
Alzheimer Disease - chemically induced
,
Alzheimer Disease - drug therapy
2022
A new mechanistic approach to overcome the neurodegenerative disorders caused by oxidative stress in Alzheimer’s disease (AD) is highly stressed in this article. Thus, a newly formulated drug (zinc ortho-methyl carbonodithioate (ZOMEC)) was investigated for five weeks on seven-week-old BALB/c male mice. ZOMEC 30 mg/kg was postadministered intraperitoneally during the third week of pentylenetetrazole (PTZ) injection. The brain homogenates of the mice were evaluated for their antioxidant potential for ZOMEC. The results including catalase (CAT), glutathione S transferase (GST), and lipid peroxidation (LPO) demonstrated that ZOMEC significantly reverted the oxidative stress stimulated by PTZ in the mouse brain. ZOMEC upregulated p-Akt/Nrf-2 pathways (also supported by molecular docking methods) to revoke PTZ-induced apoptotic protein markers. ZOMEC reversed PTZ-induced neuronal synapse deficits, improved oxidative stress-aided memory impairment, and inhibited the amyloidogenic pathway in mouse brains. The results suggested the potential of ZOMEC as a new, safe, and neurotherapeutic agent to cure neurodegenerative disorders by decreasing AD-like neuropathology in the animal PTZ model.
Journal Article
Human CD33 deficiency is associated with mild alteration of circulating white blood cell counts
2025
The single pass transmembrane protein CD33 is enriched in phagocytic and hematopoietic cell types, such as monocytes. CD33 is thought to be associated with immune cell function, susceptibility to Alzheimer’s disease, and rare leukemias. Antagonism or genetic ablation of CD33 has been proposed to treat Alzheimer’s disease, hematological cancers, and as a selection mechanism for enriching genetically altered blood cells. To understand the impact of chronic CD33 loss or ablation, we describe individuals who we confirmed to be missing CD33 due to germline loss of function variants. Through PheWAS-based approaches using existing whole exome biobanks and bespoke phenotyping using recall-by-genotype (RBG) studies, we show that CD33 loss of function alters circulating white blood cell counts and distributions, albeit mildly and with no overt clinical pathology. These findings indicate that chronic CD33 antagonism/ablation is likely to be safe in humans.
Journal Article