Biology subjects

Yerneni, S. S.

Publications and source records attributed to Yerneni, S. S..

5 recordsLinked to original sources

bioRxiv2025

Engineering 3D Skeletal Muscle Tissue with Complex Multipennate Myofiber Architectures

The hierarchical architecture of skeletal muscle spans from microscale sarcomeres to macroscale myofibers and is integral to its contractile functionality. Pathologies such as volumetric muscle loss (VML) compromise this structure and destroy the native extracellular matrix (ECM), exceeding the regenerative capacity of endogenous repair mechanisms. Here, we present a novel method for tissue engineering biomimetic three-dimensional (3D) skeletal muscle with complex architectures by leveraging freeform reversible embedding of suspended hydrogels (FRESH) 3D bioprinting of the ECM. Collagen type I scaffolds mimicking diverse muscle architectures-- including parallel, unipennate, bipennate, multipennate, and convergent--were designed, FRESH printed, and seeded with C2C12 myoblasts to guide myogenesis. Engineered muscle tissues demonstrated scaffold-mediated alignment and fusion into functional myotubes, exhibiting contractile responses to electrical stimulation with architecture-dependent specific force of [~]1 kN/m2 and a positive force-frequency relationship. In vivo implantation further revealed scaffold-directed cellular and vascular organization, underscoring the translational potential of this approach. In summary, this study demonstrates the capability to use FRESH 3D bioprinting to engineer physiologically relevant muscle architectures, significantly advancing the design of functional muscle tissues for regenerative medicine and in vitro modeling applications.

bioengineering↗

bioRxiv2024

MALT1 protease inhibition restrains glioblastoma progression by reversing tumor-associated macrophage-dependent immunosuppression

MALT1 protease is an intracellular signaling molecule that promotes tumor progression via cancer cell-intrinsic and cancer cell-extrinsic mechanisms. MALT1 has been mostly studied in lymphocytes, and little is known about its role in tumor-associated macrophages. Here, we show that MALT1 plays a key role in glioblastoma (GBM)-associated macrophages. Mechanistically, GBM tumor cells induce a MALT1-NF-{kappa}B signaling axis within macrophages, leading to macrophage migration and polarization toward an immunosuppressive phenotype. Inactivation of MALT1 protease promotes transcriptional reprogramming that reduces migration and restores a macrophage "M1-like" phenotype. Preclinical in vivo analysis shows that MALT1 inhibitor treatment results in increased immuno-reactivity of GBM-associated macrophages and reduced GBM tumor growth. Further, the addition of MALT1 inhibitor to temozolomide reduces immunosuppression in the tumor microenvironment, which may enhance the efficacy of this standard-of-care chemotherapeutic. Together, our findings suggest that MALT1 protease inhibition represents a promising macrophage-targeted immunotherapeutic strategy for the treatment of GBM. Graphical abstract. O_FIG O_LINKSMALLFIG WIDTH=196 HEIGHT=200 SRC="FIGDIR/small/614808v1_ufig1.gif" ALT="Figure 1"> View larger version (48K): org.highwire.dtl.DTLVardef@18c969eorg.highwire.dtl.DTLVardef@f48f0dorg.highwire.dtl.DTLVardef@1dbbbb1org.highwire.dtl.DTLVardef@ff8237_HPS_FORMAT_FIGEXP M_FIG The effects of tumor cell-induced CARD9-BCL10-MALT1 (CBM) activation (left) and MALT1 protease inhibition (right) on GBM associated macrophages in the tumor microenvironment. Cartoon of cellular components of a GBM tumor with an immunosuppressive TME characterized by "M2-like macrophages" (left) and conversion to a more immune-reactive tumor microenvironment characterized by "M1-like macrophages and increased effector T-cells (right) as a result of MALT1 protease inhibition. C_FIG

cancer biology↗

bioRxiv2023

Pneumococcal Extracellular Vesicles Mediate Horizontal Gene Transfer via the Transformation Machinery

Bacterial cells secrete extracellular vesicles (EVs), the function of which is a matter of intense investigation. Here, we show that the EVs secreted by the human pathogen Streptococcus pneumoniae (pneumococcus) are associated with bacterial DNA on their surface and can deliver this DNA to the transformation machinery of competent cells. These findings suggest that EVs contribute to gene transfer in Gram-positive bacteria, and in doing so, may promote the spread of drug resistance genes in the population. SignificanceThis work extends our understanding of horizontal gene transfer and the roles of extracellular vesicles in pneumococcus. This bacterium serves as the model for transformation, a process by which bacteria can take up naked DNA from the environment. Here we show that extracellular vesicles secreted by the pneumococcus have DNA on their surface, and that this DNA can be imported by the transformation machinery facilitating gene transfer. Understanding EV-mediated gene transfer may provide new avenues to manage the spread of antibiotic drug resistance.

microbiology↗

bioRxiv2023

Lipid nanoparticle structure and delivery route during pregnancy dictates mRNA potency, immunogenicity, and health in the mother and offspring

Treating pregnancy-related disorders is exceptionally challenging because many small molecule drugs on the market may cause maternal and fetal toxicity. This potential danger has hindered the development and clinical evaluation of new drugs for several decades. Lipid nanoparticle (LNP)-based RNA therapies with high delivery efficacy, favorable immune response, and minimal transplacental transport can quell maternal-fetal toxicity concerns and propel the development of pregnancy-safe drugs. To this extent, we report potent LNP structures that robustly deliver mRNA to maternal organs and placenta. Using structure-function analysis, we show that LNP efficacy is influenced by the polyamine headgroup, and toxicity is governed by the acrylate tail. Our lead nanoparticle shows robust protein expression via multiple clinically relevant administration routes in pregnant mice. In the placenta, it transfects trophoblasts, endothelial cells, and immune cells. Further, by varying ionizable lipid structure, we demonstrate that LNP immunogenicity affects organ expression and pup health during pregnancy. Immunogenic LNPs show lower efficacy in lymphoid organs in an IL-1{beta} dependent manner in pregnant mice. Further, pro-inflammatory immune responses provoke the infiltration of adaptive immune cells in the placenta and restrict pup growth after birth. Together, our results provide a mechanistic basis for designing safe and potent LNPs that can be administered during pregnancy.

bioengineering↗

bioRxiv2019

A Molecular Link between Cell Wall Modification and Stringent Response in a Gram-positive Bacteria

To ensure survival during colonization of the human host, bacteria must successfully respond to unfavorable and fluctuating conditions. This study explores the fundamental phenomenon of stress response in a gram-positive bacterium, where we investigate the ability of a cell wall modification enzyme to modulate intracellular stress and prevent the triggering of the stringent response pathway. The Streptococcus pneumoniae cell wall modification proteins MurM and MurN are tRNA-dependent amino acid ligases, which lead to the production of branched muropeptides by generating peptide crossbridges. In addition, MurM has been proposed to contribute to translation quality control by preferentially deacylating mischarged tRNAs mischarged with amino acids that make up the peptidoglycan. Here, we demonstrate that the murMN operon promotes optimal growth under stressed conditions. Specifically, when grown in mildly acidic conditions, a murMN deletion mutant displays early entry into stationary phase and dramatically increased lysis. Surprisingly, these defects are rescued by inhibition of the stringent response pathway or by enhancement of the cells ability to deacylate mischarged tRNA molecules. The increase in lysis results from the activity of LytA, and experiments in macrophages reveal that murMN regulates phagocytosis in a LytA-dependent manner. These results suggest that under certain stresses, these bacterial cells lacking MurMN likely accumulate mischarged tRNA molecules, activate the stringent response pathway, and enter prematurely into stationary phase. Moreover, by virtue of its ability to deacylate mischarged tRNAs while building peptidoglycan crossbridges, MurM can calibrate the stress response with consequences to host-pathogen interactions. Thus, MurM is positioned at the interface of cell wall modification, translation quality control and stringent response. These findings expand our understanding of the functions of the bacterial cell wall: cell wall modifications that impart structural rigidity to the cell are interlinked to the cells ability to signal intracellularly and mount a response to environmental stresses.\n\nSIGNIFICANCEDuring infection, microbes must survive the hostile environmental conditions of the human host. When exposed to stresses, bacteria activate an intracellular response, known as stringent response pathway, to ensure their survival. This study connects two fundamental pathways important for cellular growth in a gram-positive bacterium; it demonstrates that enzymes responsible for cell wall modification are connected to the stringent response pathway via their ability to ameliorate errors in protein translation. Our study was performed on Streptococcus pneumoniae where the cell wall modification enzyme, MurM, is a known determinant of penicillin resistance. We now demonstrate the importance of MurM in translation quality control and establish that it serves as a gatekeeper of the stringent response pathway.

microbiology↗