Faculty, Student Works School of Medicine
Browse by
Recent Submissions
-
Effects of Nanodysferlins on Recovery of Voltage-Induced SR Calcium Release after Osmotic Shock in Muscle Fibers from Dysferlin-null miceEarlier we showed using shock injury (OSI) that dysferlin modulates the coupling of excitation to Ca2+ release skeletal myofibers (Kerr et al., PNAS, 2013; Lukyanenko et al., Front. Physiol., 2022). Here we studied dysferlin-null A/J mouse FDB myofibers expressing fluorescent variants of nanodysferlins, created by the Sutton and Hirsch laboratories, that are missing different combinations of C2 domains, to assess their abilities to target t-tubules and to support normal Ca2+ signaling. cDNAs encoding nanodysferlins (reduced to 3 or 4 C2 domains plus the Fer/DysF domains) were provided by Drs. Hirsch and Sutton via the Jain Foundation. They were tagged at their N-terminus with Venus and electroporated into A/J FDB muscles. Expression of all four nanodysferlins was poor. When they were detected by confocal microscopy, they located in longitudinal membrane structures overlying the Z-disks typical of a compartment of the ER, not in the punctate structures typical of t-tubules. Nanodysferlins 364, 365, and 431 supported normal Ca2+ transient before OSI but behaved like untreated A/J fibers after OSI. Nanodysferlin 430 reduced the original amplitude of Ca2+ transients by ~20%, but supported their full recovery after OSI. All the nanodysferlins failed to suppress Ca2+ waves typical of CICR in myofibers exposed to OSI. Nanodysferlins with an N-terminal Venus tag express poorly in cultured A/J myofibers, mislocalize to the ER and fail to support normal Ca2+ signaling, especially after OSI. Supported by the Jain Foundation, and NIH (RO1 AR064268)
-
Dual inhibition of CDK4/6 and IL-6 pathways as a novel therapeutic approach for triple-negative breast cancer cellsTriple-negative breast cancer (TNBC) is highly aggressive and associated with poor clinical outcomes. TNBC stands as a major cause of death among breast cancer patients and offers only a few therapeutic options. Abemaciclib, a cyclin dependent kinase 4/6 (CDK4/6) inhibitor, has received FDA approval for use in hormone receptor-positive, HER2-negative, and metastatic/advanced breast cancers. However, acquired resistance to CDK4/6 inhibitors in treating TNBC is becoming an increasing concern. Our recent results indicated that CDK4/6 inhibitors can induce IL-6 levels in TNBC cells, and increased IL-6 signaling could potentially compromise the efficacy of CDK4/6 inhibitors. In this study, abemaciclib was combined with an IL-6/GP130 inhibitor (bazedoxifene). We tested the effect of the combination on cell viability, migration, and invasion of human and mouse TNBC cells. Our data demonstrated that the bazedoxifene and abemaciclib combination synergistically inhibited TNBC cell viability, migration, and invasion in vitro. These results support dual inhibition of CDK4/6 and IL-6 as a novel therapeutic approach for TNBC.
-
Neuromuscular Junction Morphology as a Biomarker for Therapeutic Efficacy in Myasthenia GravisThe neuromuscular junction (NMJ) is a complex synaptic structure linking the motor nerve to individual skeletal muscle fibers for the regulation of voluntary contraction[4]. Alterations in post-synaptic NMJ morphology are linked to muscle contractile deficits in various pathological conditions (e.g., muscular dystrophy, spinal muscular atrophy, traumatic nerve injury) as well as in aging. In autoimmune mediated Myasthenia Gravis (MG), NMJ morphology is altered by the immunologic degradation of the acetylcholine receptors (AchR’s) and the secondary effects of inflammation. Our work is focused on (1) developing NMJ morphology as a biomarker for the progression of muscle dysfunction in a rat model of MG and (2) determining if clinically effective anti-complement strategies in MG act to preserve NMJ structure. To this end we have established an image analysis pipeline in Nikon Elements to quantify pre- and post-synaptic morphology of the NMJ (bungarotoxin labeled AchR’s) and motor nerve/presynaptic structure (SV2 and neurofilament) in cryosectioned muscle samples. Using this strategy, we have begun to quantitate the change in an experimental rat model of MG and the impact of a clinically effective anti-complement strategy to mitigate these changes.
-
Role of KDM3A and EZH2 in Regulation of Glutamine Metabolism and Prostate Cancer ProgressionEpigenetic dysregulation is a hallmark of various cancers, including prostate cancer (PCa), and contributes to disease development and progression. KDM3A is a histone 3 lysine 9 (H3K9) demethylase that removes the repressive H3K9 methylation marks and promotes gene expression. EZH2, a catalytic subunit of Polycomb Repressive Complex 2 (PRC2), induces H3K27 trimethylation repressive marks to inhibit gene expression (canonical activity). In contrast to the repressive role of PRC2, we found that it interacts with KDM3A to promote transcription of selective genes such as GLUL (non-canonical activity). GLUL catalyzes de-novo glutamine synthesis that converts ammonia and glutamate to glutamine. Glutamine metabolism yields α-Ketoglutarate, an essential molecule for the tricarboxylic acid cycle (TCA). Additionally, it plays a crucial role in the synthesis of various macromolecules, including nucleotides, proteins, and hexosamine. Cancer cells including PCa cells are mostly addicted to glutamine and switch to glutamine metabolism for proliferation and survival. We aim to investigate the mechanism of transcriptional regulation of GLUL and glutamine metabolism in PCa progression due to KDM3A and PRC2 complex interaction, primarily focusing on the non-canonical role of PRC2 complex