Biology subjects

Hariharan, V.

Publications and source records attributed to Hariharan, V..

5 recordsLinked to original sources

bioRxiv2026

PDE3A-SLFN12 Molecular Glues Target Multiple KIT D816V Cell Types in Preclinical Models of Mast Cell Malignancies

A drug discovery approach was used to specifically target malignant cells with KIT D816V mutation, which is the predominant disease-causing mutation in clonal mast cell malignancies. To this end, KIT D816V cells derived from induced pluripotent stem cells (iPS cells) of KIT D816V patients were employed to screen a library of FDA approved and experimental drugs for specific killing of KIT D816V cells. We discovered the novel compound LDC 3416, which targets multiple malignant KIT D816V cell types, including hematopoietic stem/progenitor cells and mast cells. Importantly, by exploring the LDC 3416 targeting profile, we identified the phosphodiesterase 3A-Schlafen 12 (PDE3A-SLFN12) molecular glue pathway as a novel approach for specific targeting of malignant KIT D816V cells. We found that the KIT D816V mutant protein leads to increased expression of PDE3A and SLFN12 and thus confers a selective molecular vulnerability to PDE3A-SLFN12 molecular glues. Primary malignant mast cells of KIT D816V patients with indolent and advanced systemic mastocytosis also exhibit increased expression of PDE3A and SLFN12. We extended our study to include additional PDE3A-SLFN12 molecular glues and demonstrate their synergistic action with KIT D816V selective tyrosine kinase inhibitors (TKIs) in killing KIT D816V cells. Furthermore, the PDE3A-SLFN12 molecular glues also target KIT D816V megakaryocytes, a cell type that has been underestimated in malignant mast cell pathophysiology and molecular targeting. The identified molecular glues, along with their synergy with TKIs and their simultaneous targeting of multiple KIT D816V cell types, open novel treatment options for KIT D816V mast cell malignancies and other KIT D816V associated diseases.

cancer biology↗

bioRxiv2025

Proviruses in CD4+ T cells reactive to autologous antigens contribute to nonsuppressible HIV-1 viremia

Antiretroviral therapy (ART) halts HIV-1 replication, reducing plasma virus levels to below the limit of detection, but it is not curative due to a reservoir of latently infected CD4+ T cells. In some people living with HIV-1 (PLWH), plasma HIV-1 RNA becomes persistently detectable despite optimal ART. This nonsuppressible viremia (NSV) is characterized by identical, non-evolving HIV-1 RNA variants expressed from infected CD4+ T cell clones. The mechanisms driving persistent virus production from a specific population of infected cells are poorly understood. We hypothesized that proviruses in cells responding to chronic immunologic stimuli, including self-associated antigens, may drive viral gene expression and NSV. Here, we demonstrate that stimulation of CD4+ T cells with autologous cell lysates induces virus production in an MHC-II-dependent manner. In 7 of 8 participants with NSV, we recovered viral RNA released ex vivo in response to autologous cell lysates that matched plasma virus. This process involves both defective and replication-competent proviruses residing in conventional T cells, and is also observed in PLWH with undetectable viremia. These findings suggest that recognition of self-associated antigens is an important cause of HIV-1 reservoir expression, which can contribute to persistent systemic inflammation and potential rebound upon ART interruption. One sentence summaryHIV-1 viremia not suppressed by effective ART can be caused by proviruses in CD4+ T cells reactive to autologous antigens.

immunology↗

bioRxiv2025

Superinfection with intact HIV-1 results in conditional replication of defective proviruses and nonsuppressible viremia in people living with HIV-1

During replication of some RNA viruses, defective particles can spontaneously arise and interfere with wild-type (WT) virus replication. Recently, engineered versions of these defective interfering particles (DIPs) have been proposed as an HIV-1 therapeutic. However, DIPs have yet to be reported in people with HIV-1 (PWH). Here, we find DIPs in PWH who have a rare, polyclonal form of non-suppressible viremia (NSV). While antiretroviral therapy (ART) rapidly reduces viremia to undetectable levels, some individuals experience sustained viremia due to virus production from cell clones harboring intact or defective proviruses. We characterized the source of NSV in two PWH who never reached undetectable viral load despite ART adherence. Remarkably, in each participant, we found a diverse set of defective viral genomes all sharing the same fatal deletions. We found that this paradoxical accumulation of mutations by viruses with fatal defects was driven by superinfection with intact viruses, resulting in mobilization of defective genomes and accumulation of additional mutations during untreated infection. We show that these defective proviruses interfere with WT virus replication, conditionally replicate, and, in one case, have an R0 > 1, enabling in vivo spread. Despite this, clinical outcomes show no evidence of a beneficial effect of these DIPs.

microbiology↗

bioRxiv2022

Di-valent siRNA Mediated Silencing of MSH3 Blocks Somatic Repeat Expansion in Mouse Models of Huntington's Disease

Huntingtons Disease (HD) is a severe neurodegenerative disorder caused by expansion of the CAG trinucleotide repeat tract in the huntingtin gene. Inheritance of expanded CAG repeats is needed for HD manifestation, but further somatic expansion of the repeat tract in non-dividing cells, particularly striatal neurons, hastens disease onset. Called somatic repeat expansion, this process is mediated by the mismatch repair (MMR) pathway. Among MMR components identified as modifiers of HD onset, MutS Homolog 3 (MSH3) has emerged as a potentially safe and effective target for therapeutic intervention. Here, we identify fully chemically modified short interfering RNA (siRNA) that robustly silence MSH3 in vitro and in vivo. When synthesized in a di-valent scaffold, siRNA-mediated silencing of MSH3 effectively blocked CAG repeat expansion in striatum of two HD mouse models without impacting tumor-associated microsatellite instability. Our findings establish a novel paradigm for treating patients with HD and other repeat expansion diseases. One Sentence SummarySilencing MSH3 in the CNS of two models of Huntingtons disease using di-valent siRNA blocks disease-accelerating somatic expansion of CAG repeats.

molecular biology↗

bioRxiv2022

PHYSIOLOGICAL CHARACTERISTICS OF BACTERIAL DROPLETS INDICATE A CATASTROPHIC CONSEQUENCE WITH AN INCREASE IN IMPACT VELOCITY

Droplet impacts on various surfaces play a profound role in different bio-physiological processes and engineering applications. The current study opens a new realm that investigates the plausible effect of impact velocities on bacteria-laden droplets against a solid surface. We unveiled the alarming consequences of Salmonella Typhimurium (STM) laden drop, carrying out the in vitro and intracellular viability of STM to the impact Weber numbers ranging from 100-750. The specified Weber number range mimics the velocity range occurring during the respiratory processes, especially the airborne dispersion of drops during cough. A thick ring of bacterial deposition was observed in all cases irrespective of impacting velocity and the nutrient content of the bacterial medium. The mechanical properties of the bacterial deposit examined using Atomic Force Microscopy reveals the deformation of bacterial morphology, cushioning effect and adhesion energy to determine the cell-cell interactions. The impact velocity induces the shear stress onto the cell walls of STM, thereby deteriorating the in vitro viability. However, we found that even with compromised in vitro viability, Salmonella retrieved from deposited patterns impacted at higher velocity revealed an increased expression of phoP (the response regulator of the PhopQ two-component system) and uninterrupted intracellular proliferation in macrophages. The inability of STM{Delta} phoP growth in nutrient-rich dried droplets to the subjected impact velocities signifies the predominant role of phoP in maintaining the virulence of Salmonella during desiccation stress. Our findings open a promising avenue for understating the effect of bacteria-laden drop impact and its role in disease spread. O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY C_FIG_DISPLAY

bioengineering↗