Junctophilin-2 (JP2) is a structural protein required for normal excitation-contraction (E-C) coupling. Following cardiac stress, JP2 is cleaved by Ca2+-dependent protease calpain, which disrupts the E-C coupling ultrastructural machinery and drives heart failure progression. Here we demonstrate that stress-induced proteolysis of JP2 liberates an N-terminal fragment (JP2NT) that translocates to the nucleus, binds to genomic DNA and controls expression of a spectrum of genes in cardiomyocytes. Transgenic overexpression of JP2NT in mice modifies the transcriptional profile resulting in attenuated pathological remodeling in response to cardiac stress. Conversely, loss of JP2NT function accelerates stress-induced development of hypertrophy and heart failure in mutant mice. These data reveal a self-protective mechanism in failing cardiomyocytes that transduce mechanical information (E-C uncoupling) into salutary transcriptional reprogramming in the stressed heart.
Background
Gut microbiome alterations are closely related to human health and linked to a variety of diseases. Although great efforts have been made to understand the risk factors for multiple myeloma (MM), little is known about the role of the gut microbiome and alterations of its metabolic functions in the development of MM.
Results
Here, in a cohort of newly diagnosed patients with MM and healthy controls (HCs), significant differences in metagenomic composition were discovered, for the first time, with higher bacterial diversity in MM. Specifically, nitrogen-recycling bacteria such as Klebsiella and Streptococcus were significantly enriched in MM. Also, the bacteria enriched in MM were significantly correlated with the host metabolome, suggesting strong metabolic interactions between microbes and the host. In addition, the MM-enriched bacteria likely result from the regulation of urea nitrogen accumulated during MM progression. Furthermore, by performing fecal microbiota transplantation (FMT) into 5TGM1 mice, we proposed a mechanistic explanation for the interaction between MM-enriched bacteria and MM progression via recycling urea nitrogen. Further experiments validated that Klebsiella pneumoniae promoted MM progression via de novo synthesis of glutamine in mice and that the mice fed with glutamine-deficient diet exhibited slower MM progression.
Conclusions
Overall, our findings unveil a novel function of the altered gut microbiome in accelerating the malignant progression of MM and open new avenues for novel treatment strategies via manipulation of the intestinal microbiota of MM patients.
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