Reticulocytes, the precursors of erythrocytes, undergo drastic alterations in cell size, shape, and deformability during maturation. Experimental evidence suggests that young reticulocytes are stiffer and less stable than their mature counterparts; however, the underlying mechanism is yet to be fully understood. Here, we develop a coarse-grained molecular-dynamics reticulocyte membrane model to elucidate how the membrane structure of reticulocytes contributes to their particular biomechanical properties and pathogenesis in blood diseases. First, we show that the extended cytoskeleton in the reticulocyte membrane is responsible for its increased shear modulus. Subsequently, we quantify the effect of weakened cytoskeleton on the stiffness and stability of reticulocytes, via which we demonstrate that the extended cytoskeleton along with reduced cytoskeleton connectivity leads to the seeming paradox that reticulocytes are stiffer and less stable than the mature erythrocytes. Our simulation results also suggest that membrane budding and the consequent vesiculation of reticulocytes can occur independently of the endocytosis-exocytosis pathway, and thus, it may serve as an additional means of removing unwanted membrane proteins from reticulocytes. Finally, we find that membrane budding is exacerbated when the cohesion between the lipid bilayer and the cytoskeleton is compromised, which is in accord with the clinical observations that erythrocytes start shedding membrane surface at the reticulocyte stage in hereditary spherocytosis. Taken together, our results quantify the stiffness and stability change of reticulocytes during their maturation and provide, to our knowledge, new insights into the pathogenesis of hereditary spherocytosis and malaria.

Serum small extracellular vesicles (seVs) have recently drawn considerable interest because of the diagnostic and therapeutic potential of their miRnAs content. However, the characteristics of human, mouse and rat serum sEVs and their differences in small RNA contents are still unknown. In this study, through nanoparticle tracking analysis and small RNA sequencing, we found that human, rat, and mouse serum seVs exhibited distinct sizes and particle numbers as well as small RnA contents. Serum seVs contained not only abundant miRnAs but also a large number of tRnA fragments. Most serum miRnAs existed both inside and outside of seVs but were enriched in seVs. common serum seV miRNAs (188 miRNAs) and species-specific serum sEV miRNAs (265, 58, and 159 miRNAs, respectively) were identified in humans, rats, or mice. The serum sEVs contained miRNAs from tissues and organs throughout the body, with blood cells as the main contributors. In conclusion, our findings confirmed the rationality of exploring serum sEV miRNAs as noninvasive diagnostic markers and revealed great differences in serum sEV small RNAs between humans, rats, and mice. Inadequate attention to these differences and the contribution of blood cells to serum sEV miRNAs could hinder the clinical translation of basic studies. Circulating RNAs, especially microRNAs (miRNAs) have recently emerged as non-invasive disease biomarkers. miRNAs are endogenous small noncoding RNAs of approximately 22 nt that regulate gene expression posttranscriptionally by binding to target mRNA and repressing mRNA translation or increasing mRNA cleavage. Abnormally expressed miRNAs have been associated with multiple diseases. In 2008, Chen et al. reported that human serum contained numerous stable miRNAs that might originate in tissues throughout the body. The expression profiles of these miRNAs exhibit great potential to serve as novel noninvasive biomarkers for the diagnosis of cancer and other diseases 1. To date, their study has been cited more than 4,000 times, which reflects the intensive interest of researchers in serum miRNAs as noninvasive biomarkers. Exosomes are small extracellular vesicles (sEVs) (30-150 nm) that are secreted by fusion of multivesicular bodies to the plasma membrane 2. These extracellular vesicles are functional vehicles carrying a complex cargo of proteins, lipids, and nucleic acids 3. Serum exosomes are regarded as the main vector for circulating RNAs, and RNAs within exosomes are more stable and are protected from degradation by RNA enzymes 4. Increasing interest has been focused on serum exosome miRNAs as potential biomarkers for the detection of various cancers and other diseases. In the past decade, the number of publications on serum exosomal miRNAs has increased dramatically. However, there are still some questions that need to be addressed in the field. First, many studies addressing the diagnostic or therapeutic potential of serum exosomal miRNAs have been carried out with mice or rats models 5-7 , but to what extent the mouse and rat serum ex...

In this work, we assessed the anti-inflammatory effects of paeonol (PAE) in LPS-activated N9 microglia cells, as well as its underlying molecular mechanisms. PAE had no adverse effect on the viability of murine microglia N9 cell line within a broad range (0.12∼75 μM). When N9 cell line was activated by LPS, PAE (0.6, 3, 15 μM) significantly suppressed the release of proinflammatory products, such as nitric oxide (NO), interleukin-1β (IL-1β), and prostaglandin E2 (PGE2), demonstrated by the ELISA assay. Moreover, the levels of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) were significantly reduced in PAE-treated N9 microglia cells. We also examined some proteins involved in immune signaling pathways and found that PAE treatment significantly decreased the expression of TLR4, MyD88, IRAK4, TNFR-associated factor 6 (TRAF6), p-IkB-α, and NF-kB p65, as well as the mitogen-activated protein kinase (MAPK) pathway molecules p-P38, p-JNK, and p-ERK, indicating that PAE might act on these signaling pathways to inhibit inflammatory responses. Overall, we found that PAE had anti-inflammatory effect on LPS-activated N9 microglia cells, possibly via inhibiting the TLR4 signaling pathway, and it could be a potential drug therapy for inflammation-associated neurodegenerative diseases.