Microglial activation and release of inflammatory cytokines and chemokines are crucial events in neuroinflammation. Microglial cells interact and respond to other inflammatory cells such as T cells and mast cells as well as inflammatory mediators secreted from these cells. Recent studies have shown that neuroinflammation causes and accelerates neurodegenerative disease such as Parkinson’s disease (PD) pathogenesis. 1-methyl-4-phenyl-pyridinium ion (MPP+), the active metabolite of neurotoxin 1- methyl -4- phenyl -1,2,3,6-tetrahydro pyridine (MPTP) activates glial cells and mediate neurodegeneration through release of inflammatory mediators. We have shown that glia maturation factor (GMF) activates glia and induces neuroinflammation and neurodegeneration and that MPP+ activates mast cells and release proinflammatory cytokines and chemokines. The chemokine (C-C motif) ligand 2 (CCL2) levels have been shown to be elevated and play a role in PD pathogenesis. In the present study, we analyzed if MPP+ activates mouse and human mast cells to release chemokine CCL2. Mouse bone marrow-derived mast cells (BMMCs) and human umbilical cord blood-derived cultured mast cells (hCBMCs) were incubated with MPP+ (10 μM) for 24 h and CCL2 levels were measured in the supernatant media by ELISA. MPP+-significantly-induced CCL2 release from BMMCs and hCBMCs. Additionally, GMF overexpression in BMMCs obtained from wild-type mice released significantly more CCL2, while BMMCs obtained from GMF-deficient mice showed less CCL2 release. Further, we show that MPP+-induced CCL2 release was greater in BMMCs-astrocyte co-culture conditions. Uncoupling protein 4 (UCP4) which is implicated in neurodegenerative diseases including PD was detected in BMMCs by immunocytochemistry. Our results suggest that mast cells may play role in PD pathogenesis.
The ribosome represents a promising avenue for synthetic biology, but its complexity and essentiality have hindered significant engineering efforts. Heterologous ribosomes, comprising rRNAs and r-proteins derived from different microorganisms, may offer opportunities for novel translational functions. Such heterologous ribosomes have previously been evaluated in E. coli via complementation of a genomic ribosome deficiency, but this method fails to guide the engineering of refractory ribosomes. Here, we implement orthogonal ribosome binding site (RBS):antiRBS pairs, in which engineered ribosomes are directed to researcher-defined transcripts, to inform requirements for heterologous ribosome functionality. We discover that optimized rRNA processing and supplementation with cognate r-proteins enhances heterologous ribosome function for rRNAs derived from organisms with ≥76.1% 16S rRNA identity to E. coli. Additionally, some heterologous ribosomes undergo reduced subunit exchange with E. coli-derived subunits. Cumulatively, this work provides a general framework for heterologous ribosome engineering in living cells.
Impairments in macroautophagy/autophagy, which degrades dysfunctional organelles as well as long-lived and aggregate proteins, are associated with several cardiomyopathies; however, the regulation of cardiac autophagy remains insufficiently understood. In this regard, ULK1 and ULK2 are thought to play primarily redundant roles in autophagy initiation, but whether their function is developmentally determined, potentially having an impact on cardiac integrity and function remains unknown. Here, we demonstrate that perinatal loss of ULK1 or ULK2 in cardiomyocytes (cU1-KO and cU2-KO mice, respectively) enhances basal autophagy without altering autophagy machinery content while preserving cardiac function. This increased basal autophagy is dependent on the remaining ULK protein given that perinatal loss of both ULK1 and ULK2 in cU1/2-DKO mice impaired autophagy causing age-related cardiomyopathy and reduced survival. Conversely, adult loss of cardiac ULK1, but not of ULK2 (i.e., icU1-KO and icU2-KO mice, respectively), led to a rapidly developing cardiomyopathy, heart failure and early death. icU1-KO mice had impaired autophagy with robust deficits in mitochondrial respiration and ATP synthesis. Trehalose ameliorated autophagy impairments in icU1-KO hearts but did not delay cardiac dysfunction suggesting that ULK1 plays other critical, autophagy-independent, functions in the adult heart. Collectively, these results indicate that cardiac ULK1 and ULK2 are functionally redundant in the developing heart, while ULK1 assumes a more unique, prominent role in the adult heart. Abbreviations: ATG4: autophagy related 4, cysteine peptidase; ATG5: autophagy related 5; ATG7: autophagy related 7; ATG9: autophagy related 9; ATG13: autophagy related 13; CYCS: Cytochrome C; DNM1L, dynamin 1-like; MAP1LC3A: microtubule-associated protein 1 light chain 3 alpha; MAP1LC3B: microtubule-associated protein 1 light chain 3 beta; MFN1: mitofusin 1; MFN2: mitofusin 2; MT-CO1: mitochondrially encoded cytochrome c oxidase I; MYH: myosin, heavy polypeptide; NBR1: NBR1 autophagy cargo receptor; NDUFA9: NADH:ubiquinone oxidoreductase subunit A9; OPA1: OPA1, mitochondrial dynamin like GTPase; PPARGC1A, peroxisome proliferator activated receptor, gamma, coactivator 1 alpha; SDHA: succinate dehydrogenase complex, subunit A, flavoprotein (Fp); SQSTM1: sequestosome 1; ULK1: unc-51 like kinase 1; ULK2: unc-51 like kinase 2; UQCRC1: ubiquinol-cytochrome c reductase core protein 1
Autophagy is a conserved cellular process that degrades dysfunctional organelles and long‐lived proteins. Insufficient autophagy contributes to several cardiomyopathies; however, the regulation of cardiac autophagy is still evolving. To this matter, Unc‐51 like autophagy activating kinases 1 and 2 (ULK1 and ULK2) are thought to play a primarily redundant role in autophagy initiation but their function in the heart remains insufficiently understood. Here, we first studied mice with embryonic cardiac‐specific deletion of Ulk1 or Ulk2 (cU1‐KO and cU2‐KO). Unexpectedly, adult cU1‐KO and cU2‐KO mice presented enhanced basal cardiac autophagy despite unchanged expression of essential autophagy machinery proteins. Cardiac function was unaltered in these mice. We then tested if this autophagy overcompensation relied on the remaining ULK protein by studying mice with embryonic cardiac‐specific deletion of both Ulk1 and Ulk2 (cU1/2‐DKO). Indeed, autophagy was impaired in cU1/2‐DKO leading to an aging‐associated cardiomyopathy and reduced survival. Next, we tested if the overall autophagy overcompensation resulting from the loss of a single cardiac Ulk was only feasible at early stages of development by studying mice with adult deletion of either Ulk1 or Ulk2 (i.e., icU1‐KO and icU2‐KO). Interestingly, while adult loss of ULK2 had no discernable effect on cardiac autophagy or function, loss of ULK1 caused a rapidly developing cardiomyopathy, heart failure and early death. Mechanistically, adult loss of cardiac ULK1 impaired autophagy and led to an overall fissed mitochondrial reticulum with deficiencies in respiration and ATP re‐synthesis. Altogether our results demonstrate that the impact of ULK1 and ULK2 loss on cardiac autophagy and function is developmentally determined. Further, although ULK1 and ULK2 appear to have redundant roles in modulating cardiac autophagy during development, only ULK1 is essential for maintenance of basal cardiac homeostasis in adulthood.
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