Biology subjects

Allamargot, C.

Publications and source records attributed to Allamargot, C..

6 recordsLinked to original sources

bioRxiv2026

Validation and testing of an in vitro model to study medical treatments for anterior urethral stricture disease: assessing the potential efficacy of phosphodiesterase-4 (PDE4) inhibition and testosterone

ObjectiveTo 1) determine the expression and distribution of all PDE4 isozymes (A-D) along the length of the anterior urethra, 2) culture fibroblasts and epithelial cells from healthy and strictured urethras, 3) investigate an in vitro model of anterior urethral stricture disease (aUSD), and 4) assess the therapeutic potential of phosphodiesterase-4 (PDE4) inhibitors and testosterone compared to paclitaxel. MethodsThe presence and relative abundance of PDE4 isozymes (A-D) was confirmed using immunohistochemistry on 5 male cadaveric urethras. Human urethral fibroblasts (FBs) were cultured from healthy control urethras of patients undergoing vaginoplasty (n=3) and from idiopathic bulbar urethral strictures (L2S1E2) of patients undergoing urethroplasty (n=3). Epithelial cells (ECs) were cultured from a healthy control urethra and two urethral strictures. To investigate a model of aUSD, Control FBs were stimulated with TGF{beta}1 and compared to Stricture FBs on assays of cell proliferation and expression of genes relevant to aUSD pathophysiology. To test therapeutics, Stricture FBs were treated with the PDE4 inhibitor, roflumilast, testosterone (T), or paclitaxel and compared to Control FBs on the previously mentioned assays and cell viability. ResultsPDE4- A, B, and D were detected along the length of the urethra. Expression levels did not differ between urethral regions. TGF{beta}1 altered proliferation and gene expression in a dose-dependent manner. Roflumilast and T preserved cell viability and proliferation and decreased expression of genes positively associated with auSD. ConclusionUrethral FBs and ECs can be cultured from healthy and strictured surgical specimens, enabling in vitro research. PDE4 inhibitors and T may be non-cytotoxic alternatives or additions to paclitaxel for aUSD. HighlightsO_LIPDE4 isozymes A, B, and D are expressed in adult anterior urethras C_LIO_LIPDE4 is expressed equally from proximal bulbar to meatal urethra C_LIO_LIEpithelial cells and fibroblasts can be cultured from healthy and stricture urethra C_LIO_LITGF{beta}1 may not be an optimal method to model aUSD in vitro C_LIO_LIUnlike paclitaxel, roflumilast and testosterone are not toxic to urethral cells C_LI

pharmacology and toxicology↗

bioRxiv2026

Intratumoral plasma cells are required for activation of CD8+ T cells and success of immune checkpoint blockade therapy in de novo MPNSTs

BackgroundThe role of intratumoral plasma cells in immune checkpoint blockade (ICB) therapy has never been tested although their presence is linked with improved patient response and survival. Malignant peripheral nerve sheath tumors (MPNSTs) are deadly sarcomas with minimal responsiveness to ICB therapies. Strikingly, drugs inhibiting cyclin-dependent kinases 4/6 (CDK4/6) and MEK sensitize de novo MPNSTs to immunotherapy targeting programmed death-ligand 1 (PD-L1), which correlates with increased intratumoral plasma cells. Here, we tested if plasma cells mediate the MPNST response to anti-PD-L1 therapy. MethodsAnti-tumor activity of PD-L1 inhibition, with or without CDK4/6-MEK inhibition, was measured in de novo MPNSTs within wild-type versus plasma cell-deficient mice. Plasma cell-dependent effects of CDK4/6-MEK inhibition on priming the MPNST immune environment were determined by single cell transcriptomics and immunostaining. FindingsMPNSTs lacking plasma cells failed to respond to anti-PD-L1 monotherapy and were no longer sensitized to immunotherapy by CDK4/6-MEK inhibition. Plasma cell-deficient MPNSTs exposed to CDK4/6-MEK inhibitors had impaired antigen presentation on major histocompatibility class I (MHC-I) and decreased CD8+ T cell infiltration and activation. Complementary analyses of human sarcomas showed increased intratumoral plasma cell signatures prognose better patient survival. InterpretationPlasma cells favorably remodel the tumor immune environment by increasing CD8+ T cell infiltration and are critical for successful ICB therapy in MPNSTs. This work may help inform ICB treatment strategies and cancer patient stratification for many different tumor types. FundingThis research was supported by University of Iowa Sarcoma Research Program awards and NIH grants T34-GM141143, T32-GM067795, F31-CA281312, P30-CA086862, and R01-NS119322. Research in ContextO_ST_ABSEvidence before this studyC_ST_ABSFor many types of cancer, intratumoral plasma cells have been correlated with better patient survival and improved response to immune checkpoint blockade (ICB) therapies. However, the biology underlying those associations is not understood and no study has examined the requirement of plasma cells in immunotherapy response. Compelling data in malignant peripheral nerve sheath tumors (MPNSTs) showed that dual kinase inhibition of oncogenic CDK4/6 and MEK induced intratumoral plasma cell accumulation and sensitized tumors to ICB therapy. While CDK4/6-MEK inhibition is known to enhance antitumor immunity in other tumor types by CD8+ T cells or natural killer (NK) cells, a role for plasma cells has never been explored. Added value of this studyStudies were performed in MPNSTs, an under-researched cancer that normally responds poorly to ICB monotherapies. This is the first investigation to show that intratumoral plasma cells are essential for successful ICB therapy and they support anti-tumor immunity by promoting a pro-inflammatory, CD8+ T cell state involving MHC-I antigen presentation. Findings provide new insight into immunomodulatory effects of CDK4/6-MEK inhibitor therapies, revealing plasma cells are needed for those drugs to activate CD8+ T cell mediated antitumor immunity. Implications of all the available evidenceThe fundamental advance in understanding how plasma cells promote successful ICB immunotherapy is likely applicable to other solid tumors and may guide novel therapeutic strategies in which plasma cell-inducing agents are combined with ICB antibodies. Moreover, an increased presence of intratumoral plasma cells in tumor specimens may streamline clinical decisions regarding which patients are most likely to benefit from ICB therapy.

cancer biology↗

bioRxiv2025

CASZ1 regulates the rate at which outer hair cells mature and is required for hearing

The transcriptional activator ATOH1 is a master regulator of the development of mechanosensory hair-cells (HCs) in the ear. We report that the ATOH1 target gene Casz1 encodes a transcription factor that regulates the rate of outer HC (OHC) maturation by gene repression. Genetic deletion of Casz1 during (but not after) development of the mouse cochlea caused: hearing loss; abnormal organization of mechanosensory stereocilia bundles in OHCs; abnormally low F-actin density in OHC cuticular plates; progressive loss of OHCs; and mild morphological alterations in inner HCs. RNA sequencing revealed that Casz1 deletion delayed downregulation of genes expressed in immature OHCs, including the actin regulator-encoding gene Coro2a, and accelerated upregulation of genes expressed in mature OHCs. Coro2a knockdown restored the density of cuticular plate F-actin in Casz1 mutant OHCs. Our data indicate that CASZ1 regulates transcriptional and morphological maturation of OHCs, and that CASZ1 in maturing HCs is necessary for hearing.

developmental biology↗

bioRxiv2024

MIRO1 controls energy production and proliferation of smooth muscle cells

BackgroundThe outer mitochondrial Rho GTPase 1, MIRO1, mediates mitochondrial motility within cells, but implications for vascular smooth muscle cell (VSMC) physiology and its roles in vascular diseases, such as neointima formation following vascular injury are widely unknown. MethodsCarotid ligation was performed in an in vivo model of selective Miro1 deletion in smooth muscle cells. VSMC proliferation during the cell cycle and molecular mechanisms of smooth muscle cell proliferation were explored in cultured aortic VSMCs by imaging mitochondrial positioning and cristae structure and assessing the effects on ATP production, metabolic function, and interactions with components of the electron transport chain (ETC). MIRO1 expression was also analyzed in human coronary arteries, and its function was assessed via knockdown in human coronary artery VSMCs. ResultsMIRO1 was highly expressed in VSMCs within human atherosclerotic plaques. MIRO1 facilitated VSMC proliferation and neointima formation by regulating mitochondrial positioning and PDGF-stimulated ATP production and respiration, critical for cell-cycle progression at G1/S. Deletion of Miro1 disrupted mitochondrial cristae structure, diminished ETC complex I activity, and impaired supercomplex formation. Notably, restoring MIRO1 function with expression of wild type MIRO1 recovered proliferation and ATP production and respiration, whereas a mutant lacking EF hands, which are essential for mitochondrial motility, only partially rescued these effects. MIRO1 knockdown in human coronary artery VSMCs confirmed its pivotal role in mitochondrial function and VSMC proliferation. ConclusionsThis study highlights two key mechanisms by which MIRO1 regulates VSMC proliferation. First, it maintains ATP synthesis by preserving mitochondrial cristae integrity. Second, its Ca2+-dependent EF hands enable ATP-dependent mitochondrial positioning. By linking mitochondrial motility and energy production to VSMC physiology, these findings position MIRO1 as a critical regulator of vascular remodeling and a potential target for therapeutic interventions.

cell biology↗

bioRxiv2022

Dynein-mediated trafficking and degradation of nephrin in diabetic podocytopathy

Diabetic nephropathy (DN) is characterized by increased endocytosis and degradation of nephrin, a protein that comprises the molecular sieve of the glomerular filtration barrier, but the key trafficking mechanism that connects the initial endocytic events and the homeostasis of nephrin is unknown. Our work implicates cytoplasmic dynein, a transport complex that is upregulated in DN, plays a critical role in triaging the endocytosed nephrin between recycling and proteolytic pathways. Using Nephroseq platform, our transcription analysis in public DN databases revealed dynein overexpression in human DN and diabetic mouse kidney, correlated with the severity of hyperglycemia and nephropathy. The increased expression of dynein subunits was confirmed in high glucose-treated podocytes and in glomeruli isolated from streptozotocin (STZ)-induced diabetic mice. Using live cell imaging, we illustrated that dynein-mediated post-endocytic sorting of nephrin was upregulated, resulting in accelerated nephrin degradation and disrupted nephrin recycling. In diabetic podocytopathy, Dynll1 is one of the most upregulated dynein components that was recruited to endocytosed nephrin. This was corroborated by observing enhanced Dynll1-nephrin colocalization in podocytes of diabetic patients, as well as dynein-mediated trafficking and degradation of nephrin in STZ-induced diabetic mice. Knockdown of Dynll1 attenuated lysosomal degradation of nephrin and promoted its recycling, suggesting the essential role of Dynll1 in dynein-mediated mistrafficking. Defining the role of dynein-mediated mistrafficking of nephrin in diabetes will not only fill the knowledge gap about the early events of DN, but also inspire novel therapeutics that target a broad spectrum of molecular events involved in the dynein-mediated trafficking. Translational StatementDiabetic nephropathy (DN), the leading cause of end stage kidney disease in the United States, is characterized by a podocytopathy with mistrafficking and depletion of the slit diaphragm protein nephrin, which in turn compromises the podocytes function in maintaining the glomerular filtration barrier. There is a critical need to define the trafficking mechanisms underlying the depletion of nephrin. Our work implicates cytoplasmic dynein, a trafficking complex that connects diabetes-triggered endocytosis with proteolytic pathways. Delineation of the dynein-driven pathogenesis of diabetic podocytopathy will inspire new therapies that potentially target a broad spectrum of molecules involved in dynein-mediated trafficking and degradation pathways.

physiology↗

bioRxiv2021

Cardiac Specific Overexpression of Transcription Factor EB (TFEB) in Normal Hearts Induces Pathologic Cardiac Hypertrophy and Lethal Cardiomyopathy

TFEB promotes lysosomal biogenesis, autophagy, and lysosomal exocytosis. The present study characterized the consequence of inducible TFEB overexpression in cardiomyocytes in vivo. We generated cardiomyocyte-specific doxycycline inducible (Tet off) mice to achieve spatial and temporal control of TFEB overexpression, by crossing TFEB transgenic mice with mice harboring the tTA transgene (TFEB/tTA). Two weeks after doxycycline removal, an 8-fold increase in TFEB protein expression was observed in transgenic hearts. Heart weight normalized to tibia length was increased by 2.5-fold following TFEB overexpression (TFEB/tTA), characterized by induction of markers of pathological hypertrophy, such as Nppa, Nppb and Acta1, progressive contractile dysfunction and cardiac dilatation. Overexpression of TFEB resulted in premature death, associated with high degree AV block. Reversal of TFEB overexpression normalized cardiac structure and function. Mitochondrial respiration and ATP levels were preserved after 2-weeks of TFEB induction, despite reduced mitochondrial (OXPHOS) protein expression, mtDNA content, and altered mitochondrial morphology. Signaling through mTOR was induced in TFEB/tTA mice, and when inhibited by rapamycin treatment for 4 weeks, partially offset left ventricular dysfunction. Transcriptome analysis revealed early suppression of mitochondrial metabolic pathways, induction of fibrosis and altered calcium signaling. MCOLN1, a lysosomal calcium release channel, the calcineurin target RCAN1.4, and the mitochondrial calcium uniporter (MCU) were strikingly induced in TFEB/tTA mice. In summary, persistent overexpression of TFEB at high levels (8-fold protein upregulation) in cardiomyocytes promotes pathologic cardiac hypertrophy via suppression of mitochondrial bioenergetic pathways and activation of pro-fibrotic and calcium regulatory pathways.

cell biology↗