Protective effect of San Huang Pill and its bioactive compounds against ulcerative colitis in Drosophila via modulation of JAK/STAT, apoptosis, Toll, and Nrf2/Keap1 pathways

ETHNOPHARMACOLOGICAL RELEVANCE

San Huang Pill (SHP) is a prescription in Dunhuang Ancient Medical Prescription, which has the efficacy of heat-clearing and dampness-drying, and is a traditional formula for the treatment of gastrointestinal diseases. However, its efficacy and mechanism in treating ulcerative colitis (UC) are still unclear.

AIM OF THE STUDY

To investigate the protective effects of SHP and its bioactive compounds against Dextran Sulfate Sodium (DSS)-induced intestinal damage using the Drosophila melanogaster model, and to detect the molecular mechanism of SHP in the treatment of UC.

METHODS

Survival rate, locomotion, feeding, and excretion were used to explore the anti-inflammatory effects of SHP. The pharmacotoxicity of SHP was measured using developmental analysis. Intestinal integrity, intestinal length, intestinal acid-base homeostasis, and Tepan blue assay were used to analyze the protective effect of SHP against DSS-induced intestinal damage. The molecular mechanism of SHP was detected using DHE staining, immunofluorescence, real-time PCR, 16 S rRNA gene sequencing, and network pharmacology analysis. Survival rate, intestinal length, and integrity analysis were used to detect the protective effect of bioactive compounds of SHP against intestinal damage.

RESULTS

SHP supplementation significantly increased the survival rate, restored locomotion, increased metabolic rate, maintained intestinal morphological integrity and intestinal homeostasis, protected intestinal epithelial cells, and alleviated intestinal oxidative damage in adult flies under DSS stimulation. Besides, administration of SHP had no toxic effect on flies. Moreover, SHP supplementation remarkably decreased the expression levels of genes related to JAK/STAT, apoptosis, and Toll signaling pathways, increased the gene expressions of the Nrf2/Keap1 pathway, and also reduced the relative abundance of harmful bacteria in DSS-treated flies. Additionally, the ingredients in SHP (palmatine, berberine, baicalein, wogonin, rhein, and aloeemodin) had protection against DSS-induced intestinal injury, such as prolonging survival rate, increasing intestinal length, and maintaining intestinal barrier integrity.

CONCLUSION

SHP had a strong anti-inflammatory function, and remarkably alleviated DSS-induced intestinal morphological damage and intestinal homeostatic imbalance in adult flies by regulating JAK/STAT, apoptosis, Toll and Nrf2/Keap1 signaling pathways, and also gut microbial homeostasis. This suggests that SHP may be a potential complementary and alternative medicine herb therapy for UC, which provides a basis for modern pharmacodynamic evaluation of other prescriptions in Dunhuang ancient medical prescription.

Irinotecan cause the side effects on development and adult physiology, and induces intestinal damage via innate immune response and oxidative damage in Drosophila

Chemotherapy leads to significant side effects in patients, especially in the gut, resulting in various clinical manifestations and enhanced economic pressure. Until now, many of the underlying mechanisms remain poorly understood. Here, we used Drosophila melanogaster (fruit fly) as in vivo model to delineate the side effects and underlying mechanisms of Irinotecan (CPT-11). The results showed that administration of CPT-11 delayed larval development, induced imbalance of male to female ratio in offspring, shortened lifespan, impaired locomotor ability, changed metabolic capacity, induced ovarian atrophy, and increased excretion. Further, CPT-11 supplementation dramatically caused intestinal damages, including decreased intestinal length, increased crop size, disrupted gastrointestinal acid-based homeostasis, induced epithelial cell death, and damaged the ultrastructure and mitochondria structure of epithelial cells. The cross-comparative analysis between transcriptome and bioinformation results showed that CPT-11 induced intestinal damage mainly via regulating the Toll-like receptor signaling, NF-kappa B signaling, MAPK signaling, FoxO signaling, and PI3K-AKT signaling pathways. In addition, CPT-11 led to the intestinal damage by increasing ROS accumulation. These observations raise the prospects of using Drosophila as a model for the rapid and systemic evaluation of chemotherapy-induced side effects and high-throughput screening of the protective drugs.

[Dose-dense paclitaxel plus carboplatin in combination with trastuzumab neoadjuvant versus standard adjuvant therapy in human epidermal growth factor receptor-2 positive and hormone receptor negative breast cancer: a prospective cohort study]

Objective: To provide survival evidence of anthracycline-free neoadjuvant chemotherapy for patients with stages Ⅱ-Ⅲ human epidermal growth factor receptor-2 (HER-2) positive and hormone receptor (HR) negative breast cancer. Methods: The prospective cohort study was conducted at the Department of Medical Oncology of Cancer Hospital, Chinese Academy of Medical Sciences. Patients with HER-2 positive and HR negative breast cancer in stages Ⅱ-Ⅲ were enrolled to receive neoadjuvant therapy (NAT) of dose-dense paclitaxel (175 mg/m(2)) plus carboplatin (AUC=4.0) biweekly for 6 cycles in combination with trastuzumab (PCbH), and matched patients who received standard adjuvant therapy of physicians' choice were recruited for survival and safety comparison. Results: From July 2013 to November 2019, 166 patients were included (neoadjuvant 51, adjuvant 115). Compared with those who received adjuvant therapy, patients receiving NAT were younger (<35 years: 19.6% vs 5.2%, P=0.014), had larger tumors (T3: 62.7% vs 7.8%, P<0.001) and more advanced diseases (stage ⅡA: 2.0% vs 41.7%, P<0.001). Patients in the neoadjuvant group all received surgery, and 96 (83.5%) in the adjuvant group received anthracycline-and-taxane-containing regimens. A total of 98 patients (49 pairs) were matched, and the covariates between the two groups were acceptably balanced. Within a median follow-up of 46.5 (range, 14-87) months, the 4-year recurrence-free survival (RFS) rate among patients who received NAT was 73.3% (95% CI: 59.0%-87.6%), versus 80.6% (95% CI: 67.9%-93.3%) among those in the adjuvant group without statistical difference (P=0.418). A similar result was observed for the 4-year overall survival (OS) [neoadjuvant versus adjuvant: 91.5% (95% CI: 81.7%-100.0%) vs 97.8% (95% CI: 93.5%-100.0%), P=0.314]. Compared with standard adjuvant therapy, PCbH was related to less neutropenia and better cardiac safety. Conclusions: These results support the consideration of anthracycline-free neoadjuvant chemotherapy combined with anti-HER-2 therapy for patients with stages Ⅱ-Ⅲ HER-2-positive and HR-negative breast cancer. Optimized regimens with both efficacy and safety are needed and to be further investigated.

Natural products targeting Nrf2/ARE signaling pathway in the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a special chronic intestinal inflammatory disease, which is mainly divided into Crohn's disease (CD) and ulcerative colitis (UC). Its occurrence is a complex process that regulated by multiple signaling pathways, including nuclear factor erythroid 2-related factor (Nrf2)/ antioxidant response element (ARE) signaling pathway. Nrf2/ARE pathway as the central defense mechanism against oxidative stress controls the expression of many antioxidant and anti-inflammatory genes in the nucleus, and plays a crucial role in the treatment of IBD. Various studies have proved that many natural compounds target Nrf2/ARE signaling pathway to treat IBD. Here, we introduced the regulatory mechanism of the Nrf2/ARE pathway, and its role in IBD and IBD complications (intestinal fibrosis and colorectal cancer (CRC)); summarized the research progress of Nrf2 targeted natural compounds and extracts in the treatment of IBD; and finally described the intestinal microbiota that alleviate or treat IBD via activating Nrf2/ARE signaling pathway. This review highlights the potential for targeting Nrf2/ARE pathway to treat IBD.

Angelica sinensis polysaccharide extends lifespan and ameliorates aging-related diseases via insulin and TOR signaling pathways, and antioxidant ability in Drosophila

Angelica sinensis polysaccharide (ASP) is one of the principal active components of Angelica sinensis (AS) that is widely used in natural medicine and has various pharmacological activities, including antioxidant, anti-inflammatory, and enhancing immunity. However, its pharmacological role of anti-aging needs to be clarified. Here, we detected the beneficial effect and mechanism of ASP on healthy aging and aging-related diseases using the Drosophila melanogaster model. The results showed that oral administration of ASP remarkably extended lifespan, increased reproduction, improved climbing ability, and increased resistance to starvation and oxidative stress in aged flies, mainly via inhibiting insulin signaling (IIS) and TOR signaling and boosting antioxidant ability. Further, ASP supplementation protected against aging-induced intestinal homeostasis imbalance via inhibiting intestinal stem cells (ISCs) hyperproliferation and oxidative damage, improved sleep disorders via rescuing sleep rhythm in aged flies, and had a neuroprotective effect on Aβ42 transgenic flies. Taken together, our findings shed light on the possibility that ASP could increase lifespan, improve healthy aging, and ultimately reduce the incidence of age-related illnesses. It holds promise as a candidate for anti-aging intervention and treatment for aging-associated disorders.

The antioxidant effects of hedysarum polybotrys polysaccharide in extending lifespan and ameliorating aging-related diseases in Drosophila melanogaster

Hedysarum polybotrys polysaccharide (HPS) is one of the main active ingredients of Hedysarum with many health-beneficial properties, including antioxidant property, immunomodulatory, anti-inflammatory, and anti-tumor. However, the effect of HPS on anti-aging is still unclear. This study was to explore the protective function of HPS on aging and age-related diseases using Drosophila melanogaster. The results demonstrated that HPS supplementation promoted hatchability and prolonged lifespan by enhancing the antioxidative capacity. Administraction of HPS ameliorated age-related symptoms such as imbalanced intestinal homeostasis, sleep disturbances, and beta-amyloid (Aβ) induced Alzheimer's disease (AD) in flies, but did not modulate neurobehavioral deficits in the AD model of tauopathy and the Parkinson's disease (PD) model of Pink1 mutation. Overall, this study reveals that HPS has strong potential in the prevention of aging and age-related diseases, and provided a new candidate for the development of anti-aging drugs.

Regulation and mechanism of Astragalus polysaccharide on ameliorating aging in Drosophila melanogaster

Astragalus polysaccharide (APS) is a notable bioactive component of Astragalus membranaceus and has been extensively investigated for its pharmacological activities, including antioxidant, neuroprotection, and anticancer effects. However, the beneficial effects and mechanisms of APS on anti-aging diseases remain largely unknown. Here, we utilized the classic model organism Drosophila melanogaster to investigate the beneficial effects and mechanism of APS on aging-related intestinal homeostasis imbalance, sleeping disorders, and neurodegenerative diseases. The results showed that administration of APS significantly attenuated age-associated disruption of the intestinal barrier, loss of gastrointestinal acid-base balance, reduction in intestinal length, overproliferation of the intestinal stem cells (ISCs), and sleeping disorders upon aging. Furthermore, APS supplementation delayed the onset of Alzheimer's phenotypes in Aβ42-induced Alzheimer's disease (AD) flies, including the extension of lifespan and the increase in motility, but without rescuing neurobehavioral deficits in the AD model of taupathy and Parkinson's disease (PD) model of Pink1 mutation. In addition, transcriptomics was used to dissect updated mechanisms of APS on anti-aging, such as JAK-STAT signaling, Toll signaling, and IMD signaling pathways. Taken together, these studies indicate that APS plays a beneficial role in modulating aging-related diseases, thereby as a potential natural drug to delay aging.

Exposure to cytarabine causes side effects on adult development and physiology and induces intestinal damage via apoptosis in Drosophila

Cytarabine (Ara-C) is a widely used drug in acute myeloid leukemia (AML). However, it faces serious challenges in clinical application due to serious side effects such as gastrointestinal disorders and neurologic toxicities. Until now, the mechanism of Ara-C-induced damage is not clear. Here, we used Drosophila melanogaster (fruit fly) as the in vivo model to explore the side effects and mechanism of Ara-C. Our results showed that Ara-C supplementation delayed larval development, reduced lifespan, impaired locomotor capacity, and increased susceptibility to stress response in adult flies. In addition, Ara-C led to the intestinal morphological damage and ROS accumulation in the guts. Moreover, administration of Ara-C promoted gene expressions of Toll pathway, IMD pathway, and apoptotic pathway in the guts. These findings raise the prospects of using Drosophila as in vivo model to rapidly assess chemotherapy-mediated toxicity and efficiently screen the protective drugs.

Protective effect of astragalus membranaceus and its bioactive compounds against the intestinal inflammation in Drosophila

Inflammatory bowel disease (IBD) is characterized by chronic and relapsing intestinal inflammation, which currently lacks safe and effective medicines. Astragalus membranaceus (AM), also named Huangqi, is one of the most commonly used fundamental herbs in China. Here, we aimed to investigate mechanism and bioactive compounds of AM on treating sodium dodecyl sulfate (SDS)- induced colitis in Drosophila flies. Our data showed that AM extract (AME) supplementation had no toxic effect in flies, and protected flies against SDS-induced lifespan shortening, intestinal morphological damage, and colon length shortening. Moreover, AME supplementation remarkably rescued SDS-induced intestinal stem cell (ISC) overproliferation and increased reactive oxygen species (ROS) level in the intestine. Mechanistically, AME remarkably rescued the altered expression levels of genes and proteins in c-Jun N-terminal kinase (JNK) and JAK-STAT signaling pathways induced by SDS in gut. Additionally, formononetin, isoliquiritigenin, isorhamnetin, astragaloside I, astragaloside III, vanillic acid, and caffeic acid in AM had protection against SDS-induced inflammatory damage in flies. Taken together, AME could ameliorate the intestinal inflammation partially by suppressing oxidative stress-associated JNK signaling and JAK-STAT signaling pathways. AME may provide a theoretical basis for natural medicine toward treating intestinal inflammatory disease in human.

Using Drosophila melanogaster as a suitable platform for drug discovery from natural products in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic and life-treating inflammatory disease that can occur in multiple parts of the human intestine and has become a worldwide problem with a continually increasing incidence. Because of its mild early symptoms, most of them will not attract people's attention and may cause more serious consequences. There is an urgent need for new therapeutics to prevent disease progression. Natural products have a variety of active ingredients, diverse biological activities, and low toxicity or side effects, which are the new options for preventing and treating the intestinal inflammatory diseases. Because of multiple genetic models, less ethical concerns, conserved signaling pathways with mammals, and low maintenance costs, the fruit fly Drosophila melanogaster has become a suitable model for studying mechanism and treatment strategy of IBD. Here, we review the advantages of fly model as screening platform in drug discovery, describe the conserved molecular pathways as therapetic targets for IBD between mammals and flies, dissect the feasibility of Drosophila model in IBD research, and summarize the natural products for IBD treatment using flies. This review comprehensively elaborates that the benefit of flies as a perfact model to evaluate the therapeutic potential of phytochemicals against IBD.

Flos puerariae ameliorates the intestinal inflammation of Drosophila via modulating the Nrf2/Keap1, JAK-STAT and Wnt signaling

Gut homeostasis is important for human health, and its disruption can lead to inflammatory bowel disease (IBD). Flos Puerariae is a herb with a wide variety of pharmacological activities including antioxidant, antidiabetic, antialcoholismic and anti-inflammatory properties. However, the role of Flos Puerariae on treating IBD remains obscure. Here, we employed Drosophila melanogaster as a model organism to investigate the protective effect of Flos Puerariae extract (FPE) against sodium dodecyl sulfate (SDS)-induced intestinal injury. Our data showed that FPE had no toxic effect in flies, and significantly extended lifespan in SDS-inflamed flies, reduced stem cell proliferation in the midgut, and maintained intestinal morphological integrity. Furthermore, FPE remarkably recused the altered expression level of genes and proteins in Nrf2/Keap1 signaling, JAK-STAT signaling and Wnt signaling pathways in gut of inflammation flies. Thus, FPE has a protective effect against intestinal injury possibly via increasing the Nrf2/keap1 pathway and suppressing the JAK-STAT and Wnt signaling pathways, which would have tremendous potential for treating IBD.

Olfactory Senses Modulate Food Consumption and Physiology in Drosophila melanogaster

Both sensory and metabolic processes guide food intake. Olfactory inputs help coordinate food appreciation and selection, but their role in food consumption and post-feeding physiology remains poorly understood. In this study, using Drosophila melanogaster as a model system, we investigated the effects of olfactory sensory neurons (OSNs) on food consumption, metabolism, and stress responses. We found that dysfunction of OSNs affects diverse processes, including decreased food consumption, increased triacylglycerol level, enhanced stress resistance to starvation or desiccation, and decreased cold resistance. Decreased neuropeptide F receptor (NPFR) level or increased insulin activity in OSNs inhibited food consumption, while impaired NPF signaling or insulin signaling in OSNs increased resistance to starvation and desiccation. These studies provide insights into the function of the olfactory system in control of feeding behaviors and physiology.

Drosophila as a Model to Study the Mechanism of Nociception

Nociception refers to the process of encoding and processing noxious stimuli, which allow animals to detect and avoid potentially harmful stimuli. Several types of stimuli can trigger nociceptive sensory transduction, including thermal, noxious chemicals, and harsh mechanical stimulation that depend on the corresponding nociceptors. In view of the high evolutionary conservation of the mechanisms that govern nociception from Drosophila melanogaster to mammals, investigation in the fruit fly Drosophila help us understand how the sensory nervous system works and what happen in nociception. Here, we present an overview of currently identified conserved genetics of nociception, the nociceptive sensory neurons responsible for detecting noxious stimuli, and various assays for evaluating different nociception. Finally, we cover development of anti-pain drug using fly model. These comparisons illustrate the value of using Drosophila as model for uncovering nociception mechanisms, which are essential for identifying new treatment goals and developing novel analgesics that are applicable to human health.

[Efficacy and survival outcomes of dose-dense carboplatin plus paclitaxel as neoadjuvant chemotherapy for triple-negative breast cancer]

Objective: To evaluate the efficacy and survival outcomes of dose-dense (biweekly) carboplatin plus paclitaxel (PC) as neoadjuvant chemotherapy (NAC) in triple-negative breast cancer (TNBC), and to explore an optimal neoadjuvant chemotherapy regimen for TNBC. Methods: Patients diagnosed as TNBC(cT1-4N0-3M0) in Cancer Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College Between January 2008 and September 2018 who received dose-dense PC and standard 3-weekly PC as NAC were 1∶1 matched using propensity score matching (PSM) to compare the efficacy, safety and survival outcomes. Results: One hundred of TNBC patients were enrolled (50 patients were divided in dose-dense group, 50 patients in standard group). The objective response rate (ORR) of dose-dense group and standard group were both 90.0% (45/50). The grade 3-4 neutropenia in dose-dense group was less than that of standard group (32.7% vs. 68.0%, P=0.001), while the rate of ALT/AST elevation in dose-dense group was higher than that of standard group (57.1% vs. 32.0%, P=0.012). The pathological complete response (pCR) rates were 34.0% (17/50) in dose-dense group and 38.0% (19/50) in standard group, without statistically significance (P=0.677). The median follow-up time was 55 months (3-150 months). The 5-year recurrence-free survival (RFS) in dose-dense group and standard group were 83.5% and 75.2%, respectively the 5-year overall survival (OS) in dose-dense and standard group were 87.9% and 84.5% the difference were not statistically significant (P=0.322 and 0.647, respectively). Patients with residual disease (tumor size≥1 cm or lymph node positive) had poor prognosis, the 5-year RFS and OS were 59.3% and 68.5%, respectively. Conclusions: Dose-dense PC has similar efficacy with standard 3-weekly PC and has a good safety profile. Since dose-dense regimen can shorten the duration of therapy, it can be an alternative in TNBC.

Gastrodin extends the lifespan and protects against neurodegeneration in the Drosophila PINK1 model of Parkinson's disease

Gastrodin is the main bioactive ingredient of a famous Chinese herb Rhizoma Gastrodiae. Many studies have reported that gastrodin has antioxidative and neuroprotective effects, although its effect on longevity and the mechanism of neuroprotection have not been well studied. Here, we use Drosophila melanogaster as a model to investigate the longevity and neuroprotective effects of gastrodin. Gastrodin significantly extended the lifespan, increased the climbing ability, enhanced the resistance to oxidative stress, increased the enzyme activities of superoxide dismutase (SOD) and catalase (CAT), and promoted the expression of anti-oxidative genes in old flies. The food intake, reproduction and starvation resistance were not affected in flies treated with gastrodin. Moreover, gastrodin delayed the onset of Parkinson-like phenotypes in Pink1^B9 mutant flies, including the prolongation of the lifespan, rescue of the climbing ability, rescue of the progressive loss of a cluster of dopaminergic neurons in the protocerebral posterial lateral 1 region, and increase of the dopamine content in the brain. Gastrodin did not ameliorate the tau-induced neurobehavioral deficits in the fly AD model of taupathy. Together, these results indicate that gastrodin could prolong the lifespan by regulating the antioxidant ability, and protect against neurodegeneration in the Pink1^B9 model of PD. This suggests that gastrodin can be considered as an ideal therapeutic candidate for drug development towards anti-aging.

Serum Stem Cell Factor Level Predicts Decline in Kidney Function in Healthy Aging Adults

BACKGROUND AND OBJECTIVES

Stem cell factor (SCF), the ligand of the c-kit receptor, actively participates in the organ reconstruction and fibrosis associated with various diseases, including kidney disease. However, it remains unclear whether SCF plays a role in kidney aging.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

In the present study, we measured the serum SCF level, estimated glomerular filtration rate (eGFR), and other biological parameters in a Chinese Han group of 892 subjects, and explored the relationship between SCF level and renal function during aging; we sought to define novel biomarkers of kidney aging.

RESULTS

Multiple linear regression was used to select potential indicators of decline in renal function. Only age, SCF level, and 25% maximum expiratory flow (25% MEF) were significant predictors after redundancy analysis (|r| > 0.70 and P < 0.05). Multiple linear regression showed that the relationship among eGFR, SCF level, and age could be described as follows: eGFR = 154.486 - (0.846 × age) - (0.011 × SCF level).

CONCLUSIONS

We found no between-gender difference in the effect of SCF on kidney aging. In conclusion, the SCF level is an ideal biomarker of renal aging and may help to predict changes in eGFR during aging.

Novokinin inhibits gastric acid secretion and protects against alcohol-induced gastric injury in rats

Novokinin (Arg-Pro-Leu-Lys-Pro-Trp), a potent vasorelaxing and hypotensive peptide modified from ovokinin, exhibits highly selective affinity for the AT₂ receptor. However, its role in gastrointestinal functions is still not fully understood. In this study, we found that novokinin inhibited basal gastric acid secretion and protected gastric mucosa from alcohol-induced injury in a dose-related manner in rats after intracerebroventricular (i.c.v.) administration. Novokinin significantly decreased basal gastric acid output at the dose of 50 and 100 nmol/rat. The effect of novokinin on gastric acid secretion was reversed by central injection of PD 123319 (10 nmol/rat), an AT₂ receptor antagonist, and peripheral injection of indomethacin (10 mg/kg), an inhibitor of prostaglandin synthesis. Meanwhile, pre-treatment with novokinin at doses of 10, 50, and 100 nmol/rat significantly reduced the alcohol-induced gastric mucosal injury compared to the ulcer-control group, which was inhibited by indomethacin (10 mg/kg). The result showed a remarkable increase in the level of prostaglandin E2 (PGE₂), glutathione (GSH), and a decrease in malondialdehyde (MDA) after i.c.v. administration of novokinin. These findings suggest that the inhibitory effect of novokinin on gastric acid secretion is probably mediated via an AT₂ receptor-prostaglandins (PGs) pathway. The gastroprotective effect of novokinin might be attributed to the inhibition of acid secretion, the cytoprotection of PGs, and the antioxidant property.

Thermoregulatory and metabolic responses to hypoxia in the oviparous lizard, Phrynocephalus przewalskii

The effects of hypoxia on behavioral thermoregulation, rate of heating and cooling, hysteresis of heart rate, and standard metabolic rate (SMR) were investigated in Phrynocephalus przewalskii, a small size toad headed lizard. Preferred temperature (T(b)) descended when lizards were exposed to severe hypoxia (8% O(2) and 6% O(2)) for 22 h, and lizards were able to maintain preferred T(b) after one week at 12% and 8% O(2) respectively. The period of heating increased after being treated with hypoxia (12% and 8% O(2)) for one week. Hysteresis of heart rate appeared at any given body temperature and oxygen level except at 39 °C and 40 °C at 8% O(2). SMR significantly increased after one-week acclimatization to 12% and 8% O(2) when ambient temperature (T(a)) was 25 °C, however, it did not change at 35 °C. Thus, we suggest that P. przewalskii has special thermoregulatory and metabolic mechanisms to acclimatize to the hypoxic environment.

The different mechanisms of hypoxic acclimatization and adaptation in Lizard Phrynocephalus vlangalii living on Qinghai-Tibet Plateau

Phrynocephalus vlangalii is a species of lizard endemic in China, which lives on Qinghai-Tibet Plateau ranging from 2000 to 4600 m above sea level. In this study, P. vlangalii were collected from low altitude (2750 m) and high altitude (4564 m). The lizards from low altitude were acclimatized in simulated hypoxic chamber (equivalent to 4600 m) for 7, 15, and 30 days. The hematological parameters, heart weight, myocardial capillary density, and myocardial enzyme activities were examined. The results showed that acclimatization to hypoxia significantly increased hemoglobin concentration ([Hb]), hematocrit (Hct), heart weight (HW), heart weight to body mass (HW/BM), lactate dehydrogenase (LDH) activity, but markedly decreased mean corpuscular hemoglobin concentration (MCHC) and succinate dehydrogenase (SDH) activity. Red blood cell (RBC) count, body mass (BM), myocardial capillary density did not change markedly during hypoxic acclimatization. On the other hand, [Hb], Hct, MCHC, HW/BM, myocardium capillary density, and SDH activity of P. vlangalii from high altitude were remarkably higher than those from low-altitude; however, LDH activity of high-altitude P. vlangalii was lower than that of low-altitude lizards. There was no significant difference in HW or BM between populations of high-altitude and low-altitude. Based on the present data, we suggest that P. vlangalii has special anatomical, physiological, and biochemical accommodate mechanisms to live in hypoxic environment, and the regulative mechanisms are different between hypoxic acclimatization and adaptation.

HMG box transcriptional repressor HBP1 maintains a proliferation barrier in differentiated liver tissue

We previously isolated HBP1 as a target of the retinoblastoma (RB) and p130 family members and as the first of the HMG box transcriptional repressors. Our subsequent work demonstrated that HBP1 coordinates differentiation in cell culture models. In the present study, we show that HBP1 regulates proliferation in a differentiated tissue of an animal. Using transgenic mice in which HBP1 expression was specifically increased in hepatocytes under control of the transthyretin promoter, we determined the impact of HBP1 on synchronous cell cycle reentry following partial hepatectomy. Modest overexpression of HBP1 yielded a detectable cell cycle phenotype. Following a mitogenic stimulus induced by two-thirds partial hepatectomy, mice expressing the HBP1 transgene showed a 10- to 12-h delay in progression through G(1) to the peak of S phase. There was a concomitant delay in mid-G(1) events, such as the induction of cyclin E. While the delay in G(1) and S phases correlated with the slight overexpression of transgenic HBP1, the level of the endogenous HBP1 protein itself declined in S phase. In contrast, the onset of the immediate-early response following partial hepatectomy was unchanged in HBP1 transgenic mice. This observation indicated that the observed delay in S phase did not result from changes in signaling pathways leading into the G(0)-to-G(1) transition. Finally, transgenic mice expressing a mutant HBP1 lacking the N-terminal RB interacting domain showed a stronger S-phase response following partial hepatectomy. These results provide the first evidence that HBP1 can regulate cell cycle progression in differentiated tissues.