A Spacetime Odyssey of Neural Progenitors to Generate Neuronal Diversity / 神经科学通报·英文版

To understand how the nervous system develops from a small pool of progenitors during early embryonic development, it is fundamentally important to identify the diversity of neuronal subtypes, decode the origin of neuronal diversity, and uncover the principles governing neuronal specification across different regions. Recent single-cell analyses have systematically identified neuronal diversity at unprecedented scale and speed, leaving the deconstruction of spatiotemporal mechanisms for generating neuronal diversity an imperative and paramount challenge. In this review, we highlight three distinct strategies deployed by neural progenitors to produce diverse neuronal subtypes, including predetermined, stochastic, and cascade diversifying models, and elaborate how these strategies are implemented in distinct regions such as the neocortex, spinal cord, retina, and hypothalamus. Importantly, the identity of neural progenitors is defined by their spatial position and temporal patterning factors, and each type of progenitor cell gives rise to distinguishable cohorts of neuronal subtypes. Microenvironmental cues, spontaneous activity, and connectional pattern further reshape and diversify the fate of unspecialized neurons in particular regions. The illumination of how neuronal diversity is generated will pave the way for producing specific brain organoids to model human disease and desired neuronal subtypes for cell therapy, as well as understanding the organization of functional neural circuits and the evolution of the nervous system.

Improvement of detection method for acetaldehyde, butyraldehyde and isobutyraldehyde in workplace air / 中国职业医学

OBJECTIVE: To improve the standard detection method for acetaldehyde, butyraldehyde and isobutyraldehyde in the air of workplace. METHODS: Acetaldehyde, butyraldehyde and isobutyraldehyde in the air of workplace were collected using silica gel tube, desorbed with 45.0% ethanol, separated by a capillary column and detected by a flame ionization detector. RESULTS: The linear range of this method for detecting acetaldehyde, butyraldehyde and isobutyraldehyde were 1.57-1 568.00, 1.60-1 600.00 and 1.59-1 588.00 mg/L, respectively. All the correlation coefficients were greater than 0.999. The detection limits were 0.52, 0.46 and 0.54 mg/L, respectively. The desorption efficiency was 91.0%-103.0%. The within-run relative standard deviation(RSD) was 0.7%-1.7%.The between-run RSD was 2.0%-3.7%. The samples could be stored for at least 10 days at room temperature. CONCLUSION: This method can be used for simultaneous detection of acetaldehyde, butyraldehyde and isobutyraldehyde in the air of workplace.

The effect of hydrochloric acid stimulation and mechanical stretch on epithelial-mesenchymal transition in ;human lung epithelial cells / 中华危重病急救医学

Objective To investigate the effect of hydrochloric acid (HCl) stimulation and mechanical stretch on epithelial-mesenchymal transition (EMT) and hyaluronan (HA) production in human lung epithelial cells. Methods Human lung epithelial cell line BEAS-2B was cultured in vitro, which was divided into phosphate-buffer saline (PBS) + static group, HCl + static group, PBS + stretch group, and HCl + stretch group respectively in the logarithmic phase. The BEAS-2B cells in two stretching groups were challenged by cyclic stretch with 20% amplitude, frequency of 0.33 Hz, sine wave of the FX-5000T system for 48 hours. The morphology changes in cells before and after stretch were observed with inverted microscope. The protein expressions of epithelial markers E-cadherin and cytokeratin-8 (CK-8) as well as mesenchymal markers vimentin and α-smooth muscle actin (α-SMA) were determined by Western Blot. The secretion of HA was determined by enzyme linked immunosorbent assay (ELISA). Results ① It was shown by microscopic observation that BEAS-2B cells displayed cobblestone morphology, linked closely and cell polarity in PBS + static group, which did not change obviously after HCl stimulation alone. Given purely mechanical stretch after 48 hours, the cells morphology changed from cobblestone shape into long spindle, and increased intercellular space obviously. Double hit of HCl and stretch changed the cells morphology more significantly. ② It was shown by Western Blot that compared with the PBS + static group, HCl alone or combined with purely mechanical stretch after 48 hours, the expressions of E-cadherin and CK-8 were decreased, while those of vimentin and α-SMA were increased, and it was more pronounced in HCl + stretch group [the expression quantity (gray value) as base 1 in PBS + static group, E-cadherin: 0.16±0.08 vs. 1, CK-8: 0.10±0.03 vs. 1, vimentin: 3.35±0.38 vs. 1, α-SMA: 3.10±0.45 vs. 1, all P < 0.01]. ③ It was shown by ELISA that both HCl stimulation and stretch could induce BEAS-2B cells secreting HA as compared with PBS + static group (μg/L: 55.763±0.687, 63.005±0.493 vs. 49.876±1.867), and the production of HA increased more remarkably after double hit (μg/L: 78.220±1.085 vs. 49.876±1.867, P < 0.01). Conclusions Both HCl and mechanical stretch could induce EMT and increase HA secretion in human lung epithelial cells in vitro. Double hit of HCl stimulation and mechanical stretch induced EMT apparently, and further increased the production of HA.

ULK1 and JNK are involved in mitophagy incurred by LRRK2 G2019S expression

Mutations in LR RK2 (Leucine rich repeat kinase 2) are a major cause of Parkinson's disease (PD). We and others reported recently that expression of the pathogenic gainof-function mutant form of LRRK2, LRRK2 G2019S, induces mitochondrial fission in neurons through DLP1. Here we provide evidence that expression of LRRK2 G2019S stimulates mitochondria loss or mitophagy. We have characterized several LRRK2 interacting proteins and found that LRRK2 interacts with ULK1 which plays an essential role in autophagy. Knockdown of either ULK1 or DLP1 expression with shRNAs suppresses LRRK2 G2019S expression-induced mitochondrial clearance, suggesting that LRRK2 G2019S expression induces mitochondrial fission through DLP1 followed by mitophagy via an ULK1 dependent pathway. In addition to ULK1, we found that LRRK2 interacts with the endogenous MKK4/7, JIP3 and coordinates with them in the activation of JNK signaling. Interestingly, LRRK2 G2019S-induced loss of mitochondria can also be suppressed by 3 different JNK inhibitors, implying the involvement of the JNK pathway in the pathogenic mechanism of mutated LRRK2. Thus our findings may provide an insight into the complicated pathogenesis of PD as well as some clues to the development of novel therapeutic strategies.

Protective effects of a c-jun N-terminal kinase inhibitor, SP600125, against D-galactosamine/lipopolysaccharide induced acute liver failure in mice / 中华传染病杂志

Objective To investigate the protective effect of c-jun N-terminal kinase (JNK)inhibitor SP600125 against acute liver failure in mice.Methods Fifty-five male C57/BL6 mice were divided into control group (n =30) and SP600125 group (n =25).The animals were given an intraperitoneal injection of D-galactosamine (D-GalN,400 mg/kg body weight)/lipopolysaccharide (LPS,30 μg/kg body weight).The control group and SP600125 group were given 10％ dimethyl sulfoxide (15 mL/kg body weight) or SP600125 (75 mg/kg body weight) subcutaneously 12 h and 1 h before D-GalN/LPS administration,respectively.D GalN/LPS induced mouse JNK activation was detected by immunohistochemistry for phospho JNK (p-JNK).D-GalN/LPS induced mouse liver cell apoptosis was detected by immunohistochemistry for Caspase-3 and TdT-mediated-dUTP nick endlabeling (TUNEL).Serum alanine transaminase (ALT) level was tested to assess liver injury.Survival rate of mice within 24 h after D-GalN/LPS administration was observed.The comparison between groups was done by t test and survival rate was analyzed by Kaplan-Meier method.Results JNK activity in liver tissues,as indicated by observation of p-JNK positive cells by immunohistochemistry,was diminished 4 h after D-GalN/LPS administration in SP600125 group.Reduced Caspase-3 activity was observed 6 h after D-GalN/LPS administration in SP600125 group (as indicated in immunohistochemistry by Caspase-3 positive cells).Mice in SP600125 group showed significantly lower TUNEL-positive cell count than control group (43.0±24.5 vs 194.7±73.8; t=9.743,P=0.000).Serum ALT level 6 h after D-GalN/LPS administration was (24.0±54.7) U/L in SP600125 group,which was significantly lower than that in control group [(1234.4±478.4) U/L; t=4.734,P=0.0015].SP600125 also significantly improved the survival rate within 24 h after D-GalN/LPS administration (4/5 vs 1/10； x2=5.225,P=0.0223).Conclusions JNK inhibitor SP600125 exerts protective effects against D-GalN/LPS induced acute liver failure in mice by suppressing JNK activation and hepatocyte apoptosis.

Regulation of the protein stability of POSH and MLK family

Sequential activation of the JNK pathway components, including Rac1/Cdc42, MLKs (mixed-lineage kinases), MKK4/7 and JNKs, plays a required role in many cell death paradigms. Those components are organized by a scaffold protein, POSH (Plenty of SH3's), to ensure the effective activation of the JNK pathway and cell death upon apoptotic stimuli. We have shown recently that the expression of POSH and MLK family proteins are regulated through protein stability. By generating a variety of mutants, we provide evidence here that the Nterminal half of POSH is accountable for its stability regulation and its over-expression-induced cell death. In addition, POSH's ability to induce apoptosis is correlated with its stability as well as its MLK binding ability. MLK family's stability, like that of POSH, requires activation of JNKs. However, we were surprised to find out that the widely used dominant negative (d/n) form of c-Jun could down-regulate MLK's stability, indicating that peptide from d/n c-Jun can be potentially developed into a therapeutical drug.