Profiling of N6-methyladenosine methylation in porcine longissimus dorsi muscle and unravelling the hub gene ADIPOQ promotes adipogenesis in an m^(6)A-YTHDF1–dependent manner

Background Intramuscular fat(IMF)content is a critical indicator of pork quality,and abnormal IMF is also relevant to human disease as well as aging.Although N6-methyladenosine(m^(6)A)RNA modification was recently found to regulate adipogenesis in porcine intramuscular fat,however,the underlying molecular mechanisms was still unclear.Results In this work,we collected 20 longissimus dorsi muscle samples with high(average 3.95%)or low IMF content(average 1.22%)from a unique heterogenous swine population for m^(6)A sequencing(m^(6)A-seq).We discovered 70genes show both differential RNA expression and m^(6)A modification from high and low IMF group,including ADIPOQ and SFRP1,two hub genes inferred through gene co-expression analysis.Particularly,we observed ADIPOQ,which contains three m^(6)A modification sites within 3’untranslated and protein coding region,could promote porcine intramuscular preadipocyte differentiation in an m^(6)A-dependent manner.Furthermore,we found the YT521-B homology domain family protein 1(YTHDF1)could target and promote ADIPOQ mRNA translation.Conclusions Our study provided a comprehensive profiling of m^(6)A methylation in porcine longissimus dorsi muscle and characterized the involvement of m^(6)A epigenetic modification in the regulation of ADIPOQ mRNA on IMF deposition through an m^(6)A-YTHDF1-dependent manner.

A kidney-brain neural circuit drives progressive kidney damage and heart failure

Chronic kidney disease(CKD)and heart failure(HF)are highly prevalent,aggravate each other,and account for substantial mortality.However,the mechanisms underlying cardiorenal interaction and the role of kidney afferent nerves and their precise central pathway remain limited.Here,we combined virus tracing techniques with optogenetic techniques to map a polysynaptic central pathway linking kidney afferent nerves to subfornical organ(SFO)and thereby to paraventricular nucleus(PVN)and rostral ventrolateral medulla that modulates sympathetic outflow.This kidney-brain neural circuit was overactivated in mouse models of CKD or HF and subsequently enhanced the sympathetic discharge to both the kidney and the heart in each model.Interruption of the pathway by kidney deafferentation,selective deletion of angiotensin II type 1a receptor(AT1a)in SFO,or optogenetic silence of the kidney-SFO or SFO-PVN projection decreased the sympathetic discharge and lessened structural damage and dysfunction of both kidney and heart in models of CKD and HF.Thus,kidney afferent nerves activate a kidney-brain neural circuit in CKD and HF that drives the sympathetic nervous system to accelerate disease progression in both organs.These results demonstrate the crucial role of kidney afferent nerves and their central connections in engaging cardiorenal interactions under both physiological and disease conditions.This suggests novel therapies for CKD or HF targeting this kidney-brain neural circuit.

Sonic hedgehog signaling in kidney fibrosis: a master communicator

The hedgehog signaling cascade is an evolutionarily conserved pathway that regulates multiple aspects of embryonic development and plays a decisive role in tissue homeostasis. As the best studied member of three hedgehog ligands, sonic hedgehog(Shh) is known to be associated with kidney development and tissue repair after various insults. Recent studies uncover an intrinsic link between dysregulated Shh signaling and renal fibrogenesis. In various types of chronic kidney disease(CKD), Shh is upregulated specifically in renal tubular epithelium but targets interstitial fibroblasts, thereby mediating a dynamic epithelialmesenchymal communication(EMC). Tubule-derived Shh acts as a growth factor for interstitial fibroblasts and controls a hierarchy of fibrosis-related genes, which lead to the excessive deposition of extracellular matrix in renal interstitium. In this review, we recapitulate the principle of Shh signaling, its activation and regulation in a variety of kidney diseases. We also discuss the potential mechanisms by which Shh promotes renal fibrosis and assess the efficacy of blocking this signaling in preclinical settings. Continuing these lines of investigations will provide novel opportunities for designing effective therapies to improve CKD prognosis in patients.