Biomedical subjects

Sumitra Muralidhar

Publications and source records attributed to Sumitra Muralidhar.

5 recordsLinked to original sources

PubMed2026

SAIGE-GPU: accelerating genome- and phenome-wide association studies using GPUs.

MOTIVATION: Genome-wide association studies (GWAS) at biobank scale are computationally intensive, especially for admixed populations requiring robust statistical models. SAIGE is a widely used method for generalized linear mixed-model GWAS but is limited by its CPU-based implementation, making phenome-wide association studies impractical for many research groups. RESULTS: We developed SAIGE-GPU, a GPU-accelerated version of SAIGE that replaces CPU-intensive matrix operations with GPU-optimized kernels. The core innovation is distributing genetic relationship matrix calculations across GPUs and communication layers. Applied to 2068 phenotypes from 635 969 participants in the Million Veteran Program, including diverse and admixed populations, SAIGE-GPU achieved a 5-fold speedup in mixed model fitting on supercomputing infrastructure and cloud platforms. We further optimized the variant association testing step through multi-core and multi-trait parallelization. Deployed on Google Cloud Platform and Azure, the method provided substantial cost and time savings. AVAILABILITY AND IMPLEMENTATION: Source code and binaries are available for download at https://github.com/saigegit/SAIGE/tree/SAIGE-GPU-1.3.3. A code snapshot is archived at Zenodo for reproducibility (DOI: [10.5281/zenodo.17642591]). SAIGE-GPU is available in a containerized format for use across HPC and cloud environments and is implemented in R/C++ and runs on Linux systems.

Genome-Wide Association Study↗

PubMed2025

Primary care providers' perspectives on receiving opportunistic genomic results from a national study: The Million Veteran Program Return Of Actionable Results (MVP-ROAR) Study.

PURPOSE: Patients are increasingly obtaining genetic health information and integrating it into their care with the help of their primary care provider (PCP). However, PCPs may not be adequately prepared to effectively utilize genetic results. Across the Veterans Health Administration health system, the Million Veteran Program Return Of Actionable Results-Familial Hypercholesterolemia (MVP-ROAR-FH) Study clinically confirms and returns genetic results associated with familial hypercholesterolemia (FH), identified in a national biobank program. METHODS: PCPs who received their patient's genetic results through the MVP-ROAR-FH study were invited to participate in semistructured interviews, which explored PCPs' familiarity with FH, how the results affected medical management, and suggestions for process improvement. Interviews were transcribed and analyzed using directed content analysis and constant comparison methods to identify key themes. RESULTS: Interviews with 9 PCPs revealed varied levels of familiarity with genetic testing and FH. Most PCPs did not distinguish FH from common high cholesterol issues and already used similar treatment approaches. Many PCPs did not recall receiving results from the MVP-ROAR-FH study. Alerts in medical records were deemed effective for communicating results. PCPs valued genetics in informing patient care and identifying at-risk family members but noted several implementation barriers, such as additional workload and unclear medical management benefits. Recommendations for improving results disclosure included simplifying the genetic testing report and associated support documents. CONCLUSION: The study represents the first investigation into PCPs' experiences with receiving genetic test results from a biobank linked to a national healthcare system. Results suggest that PCPs generally view genetic testing as beneficial, although they may not significantly alter medical management. PCPs expressed that integrating genetics into routine care may be burdensome and require additional training, which may not be practical. The study underscores the need for accessible genetic information, which could be aided by specialized support roles or different clinical specialties assisting with incorporating genetic results into patient care.

Humans↗

PubMed2005

U94 alters FN1 and ANGPTL4 gene expression and inhibits tumorigenesis of prostate cancer cell line PC3.

BACKGROUND: Insensitivity of advanced-stage prostate cancer to androgen ablation therapy is a serious problem in clinical practice because it is associated with aggressive progression and poor prognosis. Targeted therapeutic drug discovery efforts are thwarted by lack of adequate knowledge of gene(s) associated with prostate tumorigenesis. Therefore there is the need for studies to provide leads to targeted intervention measures. Here we propose that stable expression of U94, a tumor suppressor gene encoded by human herpesvirus 6A (HHV-6A), could alter gene expression and thereby inhibit the tumorigenicity of PC3 cell line. Microarray gene expression profiling on U94 recombinant PC3 cell line could reveal genes that would elucidate prostate cancer biology, and hopefully identify potential therapeutic targets. RESULTS: We have shown that stable expression of U94 gene in PC3 cell line inhibited its focus formation in culture, and tumorigenesis in nude mice. Moreover gene expression profiling revealed dramatic upregulation of FN 1 (fibronectin, 91 +/- 16-fold), and profound downregulation of ANGPTL 4 (angiopoietin-like-4, 20 +/- 4-fold) in U94 recombinant PC3 cell line. Quantitative real-time polymerase chain reaction (QRT-PCR) analysis showed that the pattern of expression of FN 1 and ANGPTL 4 mRNA were consistent with the microarray data. Based on previous reports, the findings in this study implicate upregulation of FN 1 and downregulation of ANGPTL 4 in the anti tumor activity of U94. Genes with cancer inhibitory activities that were also upregulated include SERPINE 2 (serine/cysteine protease inhibitor 2, 7 +/- 1-fold increase) and ADAMTS 1 (a disintegrin-like and metalloprotease with thrombospondin type 1 motif, 7 +/- 2-fold increase). Additionally, SPUVE 23 (serine protease 23) that is pro-tumorigenic was significantly downregulated (10 +/- 1-fold). CONCLUSION: The dramatic upregulation of FN 1 and downregulation of ANGPTL 4 genes in PC3 cell line stably expressing U94 implicate up-regulation of FN 1 and downregulation of ANGPTL 4 in anti tumor activity of U94. Further studies are necessary to determine functional roles of differentially expressed genes in U94 recombinant PC3 cell line, and hopefully provide leads to potential therapeutic targets in prostate cancer.

Journal Article↗

PubMed2003

P53 facilitates degradation of human T-cell leukaemia virus type I Tax-binding protein through a proteasome-dependent pathway.

Human T-cell leukaemia virus type 1 (HTLV-I), the aetiological agent of adult T-cell leukaemia (ATL) and tropical spastic paraparesis (TSP/HAM), transforms human T-cells in vivo and in vitro. The Tax protein of HTLV-I is essential for cellular transformation as well as viral and cellular gene transactivation. The interaction of Tax with cellular proteins is critical for these functions. We previously isolated and characterized a novel Tax-binding protein, TRX (TAX1BP2), by screening a Jurkat T-cell cDNA library. In the present study, we present evidence that the tumour suppressor p53 targets the TRX protein for proteasome degradation. Pulse-chase experiments revealed that p53 enhanced the degradation of TRX protein and reduced the half-life from 2.0 to 0.25 h. p53 mutants R248W and R273H enhance TRX degradation suggesting a transcriptionally independent mechanism. Both HTLV-I Tax and the proteasome-specific inhibitor MG132 inhibited p53-mediated TRX protein degradation. These results suggest that TRX degradation is mediated through activation of the proteasome protein degradation pathway independent of transcriptional function of p53. Our results provide the first experimental evidence that Tax inhibits transcription-dependent and independent functions of p53.

Animals↗

PubMed2002

Transcriptional downregulation of ORF50/Rta by methotrexate inhibits the switch of Kaposi's sarcoma-associated herpesvirus/human herpesvirus 8 from latency to lytic replication.

Kaposi's sarcoma-associated herpesvirus (KSHV) encodes a cellular dihydrofolate reductase (DHFR) homologue. Methotrexate (MTX), a potent anti-inflammatory agent, inhibits cellular DHFR activity. We investigated the effect of noncytotoxic doses of MTX on latency and lytic KSHV replication in two KSHV-infected primary effusion lymphoma cell lines (BC-3 and BC-1) and in MTX-resistant BC-3 cells (MTX-R-BC-3 cells). Treatment with MTX completely prevented tetradecanoyl phorbol acetate-induced viral DNA replication and strongly decreased viral lytic transcript levels, even in MTX-resistant cells. However, the same treatment had no effect on transcription of cellular genes and KSHV latent genes. One of the lytic transcripts inhibited by MTX, ORF50/Rta (open reading frame), is an immediate-early gene encoding a replication-transcription activator required for expression of other viral lytic genes. Therefore, transcription of genes downstream of ORF50/Rta was inhibited, including those encoding the viral G-protein-coupled receptor (GPCR), viral interleukin-6, and K12/kaposin, which have been shown to be transforming in vitro and oncogenic in mice. Resistance to MTX has been documented in cultured cells and also in patients treated with this drug. However, MTX showed an inhibitory activity even in MTX-R-BC-3 cells. Two currently available antiherpesvirus drugs, cidofovir and foscarnet, had no effect on the transcription of these viral oncogenes and ORF50/Rta. MTX is the first example of a compound shown to downregulate the expression of ORF50/Rta and therefore prevent viral transforming gene transcription. Given that the expression of these genes may be important for tumor development, MTX could play a role in the future management of KSHV-associated malignancies.

Anti-Inflammatory Agents, Non-Steroidal↗