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Islet regeneration is a complex process involving multiple metabolic adaptions, but the specific characterization of the islet metabolome in relation to cell proliferation has not been established. This study aimed to investigate the metabolomic changes of regenerative islets from partial pancreatectomy (Ppx) mice and speculate underlying mechanisms. Islet samples were collected from C57/BL6 mice undergoing 70–80% Ppx or sham surgery, followed by analyses of glucose homeostasis, islet morphology, and untargeted metabolomics profiles using liquid chromatography-tandem mass spectrometry (LC-MS/MS). There is no difference in blood glucose and body weight between sham and Ppx mice. After surgery, the Ppx mice showed impaired glucose tolerance, increased Ki67 positive beta cells, and elevated beta-cell mass. LC-MS/MS analysis identified fourteen differentially changed metabolites in islets of Ppx mice, including long-chain fatty acids (e.g., docosahexaenoic acid) and amino acid derivatives (e.g., creatine). Pathway analysis based on the KEGG database revealed five significantly enriched signaling pathways including cAMP signaling pathway. Further immunostaining assay on pancreatic tissue sections showed the levels of p -CREB, a transcription factor downstream of cAMP, elevated in islets from Ppx mice. In conclusion, our results demonstrate that islet regeneration involves metabolic alterations in long-chain fatty acids and amino acid derivatives, as well as the activation of the cAMP signaling pathway. • Metabolomics analysis via LC-MS/MS was conducted in regenerative islets. • 2.Fatty acids and amino acid derivatives increased in regenerative islets. • cAMP signaling pathway activated during islet regeneration. [ABSTRACT FROM AUTHOR]

RhoA protein is a small GTPase that acts as a molecular switch. When bound to guanosine triphosphate (GTP), RhoA can activate several key signal pathways. Recently, nanobody Rh57 specific binding with GTP bound active RhoA was discovered and developed as a BRET biosensor without cytotoxicity. To further clarify the nanobody Rh57's mechanism of action, we co-expressed, purified, and crystallized the RhoA-Rh57 nanobody complex and solved the structure by X-ray diffraction with a resolution of 2.76 Å. The structure showed that the interaction is mainly through hydrogen bonds, salt bridges, aromatic-aromatic interactions, and hydrophobic interactions. The involved regions include CDR3 and non-hypervariable loop of Rh57, and the SWI switch loops of RhoA, respectively. The different SWI conformation of inactivated RhoA-GDP prevented the Rh57's binding. The possible explanation of Rh57 as a non-cytotoxic BRET intracellular tracer is that Rh57's binding did not overlap with downstream PRK1 and thus did not interfere with the downstream signaling pathway. Our research provides an in-depth understanding of how nanobodies recognize activated RhoA-GTP while not binding inactivated RhoA-GDP. This structural information may also provide critical information for further optimization of relevant nanobodies. [Display omitted] • The first structure of the activated GTP binding RhoA-nanobody complex is resolved. • The underlying mechanism of selective binding of Rh57 to active RhoA-GTP but not RhoA-GDP is explained. • The possible mechanism of Rh57-RhoA binding while not interfering with the downstream PRK1 signaling pathway is explained. [ABSTRACT FROM AUTHOR]

Highlights: [•] Caleosins in Arabidopsis are divided into two types, L-caleosin and H-caleosin. [•] L-caleosin may evolve from H-caleosin. [•] Segmental and tandem duplication are main reasons for caleosin family expansion. [•] The expression patterns of caleosins were investigated in silico. [•] Caleosin may be involved in signal transduction and lipid accumulation. [Copyright &y& Elsevier]

Highlights: [•] AG490 inhibits RANKL-induced osteoclastogenesis in RAW264.7 cells. [•] AG490 affects cell proliferation and cell cycle distribution. [•] AG490 reduces NFATc1 expression during RANKL-induced osteoclastogenesis. [•] AG490 disrupts the activation of RANKL-mediated JAK2/STAT3 signaling pathway. [•] STAT3 depletion partly mimics the effect of AG490 on RANKL-induced osteoclastogenesis. [ABSTRACT FROM AUTHOR]

Abstract: The receptor activator of nuclear factor-κB ligand (RANKL), as a member of the tumor necrosis factor (TNF) family, plays an essential role in osteoclast differentiation and function. Chemokines and their receptors have recently been shown to play critical roles in osteoclastogenesis, however, whether CXCL16–CXCR6 plays role in RANKL-mediated osteoclastogenesis is unknown. In this study, we first reported that RANKL decreased CXCR6 in a dose-dependent manner, which may be through deactivation of Akt and STAT3 signaling induced by CXCL16. Interestingly, RANKL-mediated CXCR6 reduction may be associated to the activation of STAT3 by phosphorylation. When STAT3 activation was blocked by JAK2/STAT3 inhibitor AG490, RANKL failed to shut down CXCR6 expression during osteoclastogenesis. However, CXCL16 alone did not augment RANKL-mediated osteoclast differentiation and did not alter RANKL-receptor RANK mRNA expression. These results demonstrate that reduction of CXCL16–CXCR6 is critical in RANKL-mediated osteoclastogenesis, which is mainly through the activation of JAK2/STAT3 signaling. CXCL16–CXCR6 axis may become a novel target for the therapeutic intervention of bone resorbing diseases such as rheumatoid arthritis and osteoporosis. [Copyright &y& Elsevier]