Biology subjects

Rahman, N.-T.

Publications and source records attributed to Rahman, N.-T..

4 recordsLinked to original sources

bioRxiv2025

Accelerating scRNA-seq analysis: automated cell type annotation using representation learning and vector search

Cell type annotation in single-cell RNA sequencing (scRNA-seq) experiments is the fundamental step of assigning cell types to individual cells or clusters of cells based on their gene expression profiles. This process is crucial for developing biological insights from scRNA-seq experiments. We present a service that automates cell type annotation for 10x Genomics single-cell gene expression samples, enabling researchers to rapidly and accurately categorize cells within a sample. This service operates on the basis of reverse search: it compares each cells gene expression profile against the Chan Zuckerberg CELL by GENE (CZ CELLxGENE) Census, a comprehensive repository of published scRNA-seq datasets enriched with community-annotated cell types, and yields cell type annotations through summarizing the labels associated with similar cells. The annotation algorithm employed in this service avoids reliance on predefined marker genes or tissue-specific references, providing both fine-grained and coarse annotations. These initial annotations can be further refined by investigators to suit their specific research needs.

bioinformatics↗

bioRxiv2022

Endothelial Nitric Oxide Synthase (eNOS) S1176 phosphorylation status governs atherosclerotic lesion formation

ObjectiveWe have previously demonstrated the in vivo importance of the Akt-eNOS substrate-kinase relationship, as defective postnatal angiogenesis characteristic of global Akt1-null mice is rescued when bred to gain-of-function eNOS S1176D mutant mice. While multiple studies support the vascular protective role of endothelial NO generation, the causal role of Akt1-dependent eNOS S1176 phosphorylation during atherosclerotic plaque formation is not yet clear. Approach & ResultsWe herein bred congenic loss-of-function eNOS S1176A and gain-of-function eNOS S1176D mutant mice to the exacerbated atherogenic Akt1-/-; ApoE-/- double knockout mice to definitively test the importance of Akt-mediated eNOS S1176 phosphorylation during atherogenesis. We find that a single amino acid substitution at the eNOS S1176 phosphorylation site yields divergent effects on atherosclerotic plaque formation, as an eNOS phospho-mimic aspartate (D) substitution at S1176 leads to favorable lipid profiles and decreased indices of atherosclerosis, even when on a proatherogenic Akt1 global deletion background. Conversely, mice harboring an unphosphorylatable mutation to alanine (S1176A) result in increased plasma lipids, increased lesion formation and cellular apoptosis, phenocopying the physiological consequence of eNOS deletion and/or impaired enzyme function. Furthermore, gene expression analyses of whole aortas indicate a combinatorial detriment from NO deficiency and Western Diet challenge, as loss-of-function eNOS SA mice on a Western diet present a unique expression pattern indicative of augmented T-cell activity when compared to eNOS S1176D mice. ConclusionsBy using genetic epistasis approaches, we conclusively demonstrate that Akt-mediated eNOS S1176 phosphorylation and subsequent eNOS activation remains to be the most physiologically relevant method of NO production to promote athero-protective effects.

physiology↗

bioRxiv2022

Injury suppresses Ras cell competitive advantage through enhanced wild-type cell proliferation

Healthy skin is a tapestry of wild-type and mutant clones. Although injury can cooperate with Ras mutations to promote tumorigenesis, the consequences in genetically mosaic skin are unknown. Here, we show that wild-type cells prevent oncogenic Ras-induced aberrant growth after injury. Although HrasG12V/+ and KrasG12D/+ cells outcompete wild-type cells in uninjured, mosaic tissue, their competitive advantage is suppressed after injury due to a selective increase in wild-type cell proliferation. EGFR inhibition abolishes the competitive advantage of wild-type cells after injury of HrasG12V/+-mosaic skin. Global loss of the cell cycle inhibitor p21 increases wild-type cell proliferation even without injury, suppressing the competitive advantage of HrasG12V/+ cells. Thus, injury plays an unanticipated role in switching the competitive balance between oncogenic and wild-type cells in genetically mosaic skin. One sentence SummaryInjury-repair selectively induces wild-type cell proliferation to suppress oncogenic growth in Ras-mosaic skin epithelium.

cell biology↗

bioRxiv2021

Peer teaching as bioinformatics training strategy: incentives, challenges, and benefits.

As biomedical research becomes more data-intensive, bioinformatics is becoming essential to understanding biological processes, systems, and diseases. In this paper we describe the use of a series of peer teaching workshops as a strategy to respond to the bioinformatics training needs at a research-intensive institution. In addition to the data collected from the workshops, we also used personal experiences of researchers who participated as peer teachers to understand the incentives, challenges, and benefits of peer teaching. Developing communication skills such as confidence in teaching, explaining complex concepts, and better understanding of the topic emerged as primary benefits that the teachers obtained from this experience. Lack of time for teaching and the struggles of classroom management were identified as two major challenges. We suggest that peer teaching can be beneficial not only to train researchers in bioinformatics, but also as a professional development opportunity for graduate students and postdoctoral trainees.

scientific communication and education↗