Changes in the Anatomic and Microscopic Structure and the Expression of HIF-1α and VEGF of the Yak Heart with Aging and Hypoxia

Comparative Molecular and Biological Characteristic of the Systemic Inflammatory Response in Adult and Old Male Wistar Rats with Different Resistance to Hypoxia

Morphological, molecular, and biological features of the systemic inflammatory response induced by LPS administration were assessed in adult and old male Wistar rats with high and low resistance to hypoxia. In 6 h after LPS administration, mRNA expression levels of Hif1a, Vegf, Nfkb, and level of IL-1β protein in old rats were higher than in adult rats regardless of hypoxia tolerance. The morphometric study showed that the number of neutrophils in the interalveolar septa of the lungs was significantly higher in low-resistant adult and old rats 6 h after LPS administration. Thus, in old male Wistar rats, systemic inflammatory response is more pronounced than in adult rats and depends on the initial tolerance to hypoxia, which should be considered when developing new approaches to the therapy of systemic inflammatory response in individuals of different ages.

Study of Transcriptomic Analysis of Yak (Bos grunniens) and Cattle (Bos taurus) Pulmonary Artery Smooth Muscle Cells under Oxygen Concentration Gradients and Differences in Their Lung Histology and Expression of Pyruvate Dehydrogenase Kinase 1-Related Factors

The aim of this study was to investigate the molecular mechanisms by which hypoxia affects the biological behavior of yak PASMCs, the changes in the histological structure of yak and cattle lungs, and the relationships and regulatory roles that exist regarding the differences in the distribution and expression of PDK1 and its hypoxia-associated factors screened for their role in the adaptation of yak lungs to the plateau hypoxic environment. The results showed that, at the level of transcriptome sequencing, the molecular regulatory mechanisms of the HIF-1 signaling pathway, glucose metabolism pathway, and related factors (HK2/PGK1/ENO1/ENO3/ALDOC/ALDOA) may be closely related to the adaptation of yaks to the hypoxic environment of the plateau; at the tissue level, the presence of filled alveoli and semi-filled alveoli, thicker alveolar septa and basement membranes, a large number of erythrocytes, capillary distribution, and collagen fibers accounted for all levels of fine bronchioles in the lungs of yaks as compared to cattle. A higher percentage of goblet cells was found in the fine bronchioles of yaks, and PDK1, HIF-1α, and VEGF were predominantly distributed and expressed in the monolayers of ciliated columnar epithelium in the branches of the terminal fine bronchioles of yak and cattle lungs, with a small amount of it distributed in the alveolar septa; at the molecular level, the differences in PDK1 mRNA relative expression in the lungs of adult yaks and cattle were not significant (p > 0.05), the differences in HIF-1α and VEGF mRNA relative expression were significant (p < 0.05), and the expression of PDK1 and HIF-1α proteins in adult yaks was stronger than that in adult cattle. PDK1 and HIF-1α proteins were more strongly expressed in adult yaks than in adult cattle, and the difference was highly significant (p < 0.01); the relative expression of VEGF proteins was not significantly different between adult yaks and cattle (p > 0.05). The possible regulatory relationship between the above results and the adaptation of yak lungs to the plateau hypoxic environment paves the way for the regulatory mechanisms of PDK1, HIF-1α, and VEGF, and provides basic information for studying the mechanism of hypoxic adaptation of yaks in the plateau. At the same time, it provides a reference for human hypoxia adaptation and a target for the prevention and treatment of plateau diseases in humans and plateau animals.

Label-free proteomic analysis reveals an estrous cycle transition between the follicular phase and the luteal phase in yak ovary

In order to further study the physiological mechanism about yak reproduction for the improvement of its fertility, differentially expressed proteins (DEGs) of the ovary were screened during the follicular and luteal phases of yak based on label-free quantitative proteomics. The main research results were as follows: it discovered 2867 proteins during the follicular phase and 2180 proteins during the luteal phase, among which there were 2011 proteins of expression during both phases, 856 during the follicular phase, and 169 during the luteal phase. According to the bioinformatics and Gene Ontology analysis, the screened differentially expressed proteins were mostly located in the cell membrane and extracellular region and primarily acted on the activity of laminin. Kyoto Encyclopedia of Genes and Genomes analysis indicated that the main involvement of differentially expressed proteins included steroid biosynthesis, chemokine signaling pathway, protein processing in the endoplasmic reticulum, glycerol phospholipid metabolism, carbon metabolism, PI3K-Akt signaling pathways, PPAR signaling pathways, nucleotide oligomerization domain (NOD) receptor signaling pathways, and purine metabolic pathways. Screened proteins related to reproductive function, so as to lay a theoretical foundation for the in-depth study of the regulation mechanism of yak reproduction and improve its fertility.

Expression Analysis of Molecular Chaperones Hsp70 and Hsp90 on Development and Metabolism of Different Organs and Testis in Cattle (Cattle-yak and Yak)

Hsp70 and Hsp90 play an important role in testis development and spermatogenesis regulation, but the exact connection between Hsp70 and Hsp90 and metabolic stress in cattle is unclear. Here, we focused on the male cattle−yak and yak, investigated the expression and localization of Hsp70 and Hsp90 in their tissues, and explored the influence of these factors on development and metabolism. In our study, a total of 54 cattle (24 cattle−yaks and 30 yaks; aged 1 day to 10 years) were examined. The Hsp90 mRNA of the cattle−yak was first cloned and compared with that of the yak, and variation in the amino acid sequence was found, which led to differences in protein spatial structure. Using real-time quantitative PCR (RT-qPCR) and Western blot (WB) techniques, we investigated whether the expression of Hsp70 and Hsp90 mRNA and protein are different in the cattle−yak and yak. We found a disparity in Hsp70 and Hsp90 mRNA and protein expression in different non-reproductive organs and in testicular tissues at different stages of development, while high expression was observed in the testes of both juveniles and adults. Moreover, it was intriguing to observe that Hsp70 expression was significantly high in the yak, whereas Hsp90 was high in the cattle−yak (p < 0.01). We also examined the location of Hsp70 and Hsp90 in the testis by immunohistochemical (IHC) and immunofluorescence (IF) techniques, and the results showed that Hsp70 and Hsp90 were positive in the epithelial cells, spermatogenic cells, and mesenchymal cells. In summary, our study proved that Hsp70 and Hsp90 expressions were different in different tissues (kidney, heart, cerebellum, liver, lung, spleen, and testis), and Hsp90 expression was high in the testis of the cattle−yak, suggesting that dysplasia of the cattle−yak may correlate with an over-metabolism of Hsp90.

The adaptive strategies of yaks to live in the Asian highlands

The yak (Bos grunniens), an indigenous herbivore raised at altitudes between 3,000 and 5,000 m above sea level, is closely linked to more than 40 ethnic communities and plays a vital role in the ecological stability, livelihood security, socio-economic development, and ethnic cultural traditions in the Asian highlands. They provide the highlanders with meat, milk, fibres, leather and dung (fuel). They are also used as pack animals to transport goods, for travel and ploughing, and are important in many religious and traditional ceremonies. The Asian highlands are known for an extremely, harsh environment, namely low air temperature and oxygen content and high ultraviolet light and winds. Pasture availability fluctuates greatly, with sparse pasture of poor quality over the long seven-month cold winter. After long-term natural and artificial selections, yaks have adapted excellently to the harsh conditions: 1) by genomics, with positively selected genes involved in hypoxia response and energy metabolism; 2) anatomically, including a short tongue with a weak sense of taste, and large lung and heart; 3) physiologically, by insensitivity to hypoxic pulmonary vasoconstriction, maintaining foetal haemoglobin throughout life, and low heart rate and heat production in the cold season; 4) behaviourlly, by efficient grazing and selecting forbs with high nutritional contents; 5) by low nitrogen and energy requirements for maintenance and low methane emission and nitrogen excretion, namely, 'Low-Carbon' and 'Nitrogen-Saving' traits; 6) by harboring unique rumen microbiota with a distinct maturation pattern, that has co-evolved with host metabolism. This review aims to provide an overview of the comprehensive adaptive strategies of the yak to the severe conditions of the highlands. A better understanding of these strategies that yaks employ to adapt to the harsh environment could be used in improving their production, breeding and management, and gaining benefits in ecosystem service and a more resilient livelihood to climate change in the Asian highlands.

Effects of PHD and HSP90 on erythropoietin production in yak (Bos grunniens) renal interstitial fibroblast-like cells under hypoxia

Erythropoietin (EPO), a central protein of erythropoiesis, plays an important role during hypoxia adaptation and is regulated by hypoxia-inducible factor (HIF). However, there is no report on EPO-producing cells and their regulatory mechanisms in yak (Bos grunniens). To understand EPO production and regulation of yak, kidneys from different age of yak were collected and expression of EPO, hypoxia-inducible factor 1 alpha (HIF-1α), and hypoxia-inducible factor 2 alpha (HIF-2α) were detected. Then renal tubule epithelial cells (RTECs) and peritubular interstitial fibroblast-like (RIFs) cells were isolated and cultured to determine their EPO production abilities. Subsequently, the cells were treated with dimethyloxalylglycine (DMOG) and Geldanamycin (GA), which are inhibitors of prolyl-4-hydroxylase domain (PHD) and heat shock protein 90 (HSP90) respectively, and siRNAs of HIF-1α and HIF-2α to explore their effect on EPO production and regulation. The results showed that expressions of EPO, HIF-1α, and HIF-2α were different in the different age groups of yak. High DMOG concentration caused a corresponding increase in the levels of HIF-1α and HIF-2α in RIFs and RTECs, however, EPO levels increased in RIFs only and was not detected at any concentration in RTECs; suggesting that EPO was produced in RIFs. Upon treating RIFs with siRNAs of HIF-1α and HIF-2α, we found that EPO was regulated by PHD through HIF-2α. In addition, increasing GA concentration caused a decrease in expression of HSP90, HIF-1α, HIF-2α, and EPO in RIFs. In conclusion, these findings support our proposition that PHD regulates EPO via HIF-2α in yak RIFs, while HSP90 impelled EPO expression.

Age-related differences in hypoxia-associated genes and cytokine profile in male Wistar rats

Hypoxia tolerance of the organism depends on many factors, including age. High newborn organisms tolerance and high level of oxidative stress throughout aging were demonstrated by many studies. However, there is lack of investigations reflecting the expression of key hypoxia-inducible factor HIF in different age organisms in correlation to levels of pro-inflammatory and anti-inflammatory cytokines. Liver is a sensitive to hypoxia organ, and is an important organ in providing an acute reaction to infections – it synthesizes acute inflammation phase proteins, in particular, C-reactive protein. The aim of study was to determine relationship between age-related tolerance to hypoxia and HIF-1 and PHD2 (prolyl hydroxylase domain protein) expression levels in the liver and the production of cytokines in the spleen in newborn, prepubertal and adult Wistar rats. Newborn rats are characterized by high mRNA Hif-1α expression level in the liver, accompanied by a low content of HIF-1 protein and high level of PHD2. The growth in HIF-1α protein level throughout age is accompanied by the growth of pro-inflammatory cytokines level. Prepubertal animals are the least hypoxia resistant and their HIF-1α mRNA expression level was higher than in adult animals. The PHD2 activity in prepubertal animals was significantly reduced in comparison to newborn rats, and the HIF-1α protein level did not change. Further studies require the identification of additional mechanisms, determining the regulation of the HIF-1α level in prepubertal animals.

Altered Hypoxia-Induced and Heat Shock Protein Immunostaining in Secondary Hair Follicles Associated with Changes in Altitude and Temperature in Tibetan Cashmere Goats

This experiment compared secondary hair follicles (SFs) in Tibetan cashmere goats from two different steppes that were at different altitudes and had different temperatures. Twenty-four 2-year-old goats were studied. Twelve goats were from Rikaze in Tibet which is at an altitude of above 5000 m with an average temperature of 0 °C. The other 12 studied goats were from Huan County of Gansu Province which is around 2000 m above sea level with an average temperature of 9.2 °C. The structural features of SFs were assessed using light microscopy and transmission electron microscopy. The presence of HIF-1a, HIF-2a, HIF-3a, HSP27, and HOXC13 proteins was studied using immunohistochemistry and immunofluorescence. Light and electron microscopy revealed that the SFs of the Tibetan cashmere goats that lived in the Rikaze Steppe were in the proanagen stage in May. However, the SFs of the goats from the lower warmer Huan County were in the anagen stage at the same time. Immunohistochemistry revealed intense immunostaining for HIF-1a protein in the inner root sheath (IRS) and hair shaft (HS); immunostaining against HIF-2a in the outer root sheath (ORS) and IRS; HIF-3a protein immunostaining in the ORS; HSP27 immunostaining in the ORS, IRS, and HS; and HOXC13 immunostaining in the ORS and HS. HIF-1a protein expression in the IRS and HS was higher than the expression in the ORS (p < 0.05) while the expression of HIF-2a protein was higher in the ORS and IRS than the HS (p < 0.05). The expression of HIF-3a protein was higher in the ORS than in the IRS (p < 0.05). Expression of HOXC13 protein was higher in the ORS than in the IRS and HS (p < 0.05). Immunostaining of HIF-1a, HIF-2a, and HSP27 protein was significantly higher in SFs from cashmere goats from Rikaze than in goats from Huan (p < 0.05). In contrast, HOX13 protein immunostaining was significantly higher in cashmere goats from Huan than from Rikaze (p < 0.05). Significant differences were observed in the SFs of cashmere goats from two locations that differ in altitude and temperature. This suggests the differences in the secondary hair follicles could be due to the hypoxia and lower temperatures experienced by the goats in Rikaze. These results are useful in understanding how altitude and temperature influence SF development. Hair produced by the SFs are used for down fiber. Therefore, understanding of the factors that influence SF development will allow the production and harvest of these valuable fibers to be maximized.

Molecular cloning, sequence, and expression patterns of DNA damage induced transcript 3 (DDIT3) gene in female yaks (Bos grunniens)

Endoplasmic reticulum stress (ERS) plays an important role in regulating the reproductive process of female mammals, mainly involved in follicular atresia and corpus luteum regression. DNA damage induced transcript 3 (DDIT3) is a marker gene of ERS. The objectives of the present study were to clone and analyze the sequence and tissue expression characteristics of DDIT3 gene in female yaks. By reverse transcriptase-polymerase chain reaction (RT-PCR) strategy, we obtained full-length 507-bp DDIT3-cDNA, encoding for 168-aa protein. Yak DDIT3 exhibited highest and least identity with that of bison and horse, respectively. Real-time PCR analyses revealed that the expression level of DDIT3 gene in ovary was higher than that in heart, liver, kidney, spleen, lung, uterus and oviduct (p < 0.05). DDIT3 expression level in ovary and uterus during pregnancy was higher than that in follicular phase, luteal phase and fetus stage. DDIT3 was highly expressed in metaphase II oocytes and granulosa cells than that in germinal vesicle and metaphase I oocytes (p < 0.05), respectively. This is the first molecular characterization and expression patterns of DDIT3 gene in female yaks. These results indicated that the DDIT3 gene possibly plays an important role in regulating ovary function and pregnancy maintenance in yaks.

Using weighted gene co-expression network analysis (WGCNA) to identify the hub genes related to hypoxic adaptation in yak (Bos grunniens)

BACKGROUND

As a mammal living at the highest altitude in the world, the yak has strong adaptability to the harsh natural environment (such as low temperature, scarce food, especially low oxygen) of Qinghai-Tibet Plateau (QTP) after a long process of natural selection.

OBJECTIVE

Here, we used Weighted Correlation Network Analysis (WGCNA), a systematic biology method, to identify hypoxic adaptation-related modules and hub genes. The research of the adaptability of yak against hypoxia is of great significance to identify the genetic characteristics and yak breeding.

METHODS

Based on the transcriptome sequencing data (PRJNA362606), the R package DESeq2 and WGCNA were conducted to analyze differentially expressed genes (DEGs) and construct the gene co-expression network. The module hub genes were identified and characterized by the correlation of gene and trait, module membership (kME). In addition, GO and KEGG enrichment analyses were used to explore the functions of hub genes.

RESULTS

Our results revealed that 1098, 1429, and 1645 DEGs were identified in muscle, spleen, and lung, respectively. Besides, a total of 13 gene co-expression modules were detected, of which two hypoxic adaptation-related modules (saddlebrown and turquoise) were found. We identified 39 and 150 hub genes in these two modules. Functional enrichment analyses showed that 12 GO terms and 18 KEGG pathways were enriched in the saddlebrown module while 85 GO terms and 22 KEGG pathways were enriched in the turquoise module. The significant pathways related to hypoxia adaptation include FoxO signaling pathway, Thermogenesis pathway, and Retrograde endocannabinoid signaling pathway, etc. CONCLUSIONS: In this study, we obtained two hypoxia-related specific modules and identified hub genes based on the connectivity by constructing a weighted gene co-expression network. Function enrichment analysis of two modules revealed mitochondrion is the most important organelle for hypoxia adaptation. Moreover, the insulin-related pathways and thermogenic-related pathways played a major role. The results of this study provide theoretical guidance for further understanding the molecular mechanism of yak adaptation to hypoxia.

The mechanisms of vascular aging

Vascular senescence is one of the hotspots in current research. With global average life expectancy increasing, delaying or reducing aging and age-related diseases has become a pressing issue for improving quality of life. Vascular senescence is an independent risk factor for age-related cardiovascular diseases (CVD) and results in the deterioration of CVD. Nevertheless, the underlying mechanisms of the vascular senescence have not been expressly illustrated. In this review, we attempt to summarize the recent literature in the field and discuss the major mechanisms involved in vascular senescence. We also underline key molecular aspects of aging-associated vascular dysfunction in the attempt to highlight potential innovative therapeutic targets to delay the onset of age-related diseases.

Effects of Aging on Angiogenic and Muscle Growth-Related Factors in Naturally Aged Rat Skeletal Muscles

Background

This study explored the effects of aging on the expression of angiogenic and muscle protein synthesis factors, as well as the number of satellite cells affecting sarcopenia in naturally aged rat skeletal muscles.

Methods

We divided 16 Sprague-Dawley rats into young (12 weeks old, n=8) and old (24 months old, n=8) groups and compared muscle and body weight (BW) between them. We also analyzed the expression levels of angiogenic and muscle growth proteins in soleus (slow-twitch) and extensor digitorum longus (EDL; fast-twitch) muscles by western blotting and assessed the number of skeletal muscle satellite cells and myonuclei and mean fiber cross-sectional area (CSA) using by immunofluorescence staining.

Results

EDL/BW was significantly lower in old rats than in young rats (p=0.002). The vascular endothelial growth factor level in soleus muscles was significantly lower in old rats than in young rats (p=0.001). Hypoxia-inducible factor 1-alpha and fetal liver kinase 1 levels in EDL muscles were lower in old rats than in young rats (p=0.001). The mammalian target of rapamycin (mTOR), p70S6K, and 4E-BP1 levels were significantly lower in the soleus muscles of old rats than in those of young rats (p<0.01). Similarly, insulin growth factor-1, Akt, mTOR, and p70S6K levels were significantly lower in EDL muscles of old rats than in those of young rats (p<0.01). Additionally, myonuclei/fiber, Pax7/fiber, and mean fiber CSAs in both muscle types were significantly lower in old rats than in young rats (p<0.01).

Conclusion

These data suggest different regulation of indices of angiogenic and muscle growth with aging in different muscle types.

Effects of Aging on Expression of Mic60 and OPA1 and Mitochondrial Morphology in Myocardium of Tibetan Sheep

Simple Summary

Mitochondria play a crucial role in the adaptation to high altitude hypoxia environment in Tibetan sheep, and the changes of its morphology and structure directly affect its function. OPA1 and Mic60 are important mitochondria-shaping proteins that work together to regulate the morphology of mitochondrial inner membrane and cristae. It has been shown that aging affects the expression of OPA1 and Mic60 in mice, but it has not been investigated in sheep and hence it is not known whether it might affect the ultrastructure of mitochondria. In this context, reverse transcription-quantitative PCR (RT-qPCR), enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry method were used to measure the expression of Mic60 and OPA1 genes and proteins in myocardium of adult and aged Tibetan sheep, and the ultrastructure of mitochondria were compared by transmission electron microscope. The results suggest that aging can reduces the expression of Mic60 and OPA1 genes and OPA1 protein, which can affect the mitochondrial function.

Abstract

In order to investigate the effects of aging on the expression of Mic60 and OPA1 and mitochondrial morphology in plateau animals, the expression of Mic60 and OPA1 genes and proteins, and the morphology of mitochondria in the myocardium of adult and aged Tibetan sheep were investigated. The expression of Mic60 and OPA1 genes and OPA1 protein were higher (p < 0.05) in the myocardium of adult Tibetan sheep than in those of the aged ones. The number of mitochondrial cristae in the myocardium of adult was higher than that in aged (p < 0.05). The density of mitochondria in the myocardium of adult was higher than that in aged (p < 0.01). Compared with the adult Tibetan sheep, the mitochondrial crista of aged were relatively sparse, the crista membrane was wide, and the mitochondria were not closely linked, showing fragmentation. These results suggest that the myocardial mitochondria of the adult have better energy supply ability, indicating that aging can lead to the weakening of oxygen supply in the myocardial mitochondria of Tibetan sheep.

Evolutionary Adaptation of Aquaporin-4 in Yak (Bos grunniens) Brain to High-Altitude Hypoxia of Qinghai-Tibetan Plateau

Background: In high-altitude animals, brain cell resilience against hypoxia stress is one critical evolutionary step that has promoted individual survival and species adaptation to the environment. Aquaporin-4 (AQP4) is implicated in a number of physiopathological processes, particularly in the development of brain edema, and other functions such as the regulation of extracellular space volume, potassium buffering, waste clearance, and calcium signaling. Still, the role of AQP4 in the adaptation to high-altitude hypoxia remains unknown. The yak (Bos grunniens) is the only large mammal that is currently known to have adapted to the high-altitude hypoxic environment of the Qinghai-Tibet Plateau (>4000 m above sea level). Methods: In this study, we cloned the complementary DNA (cDNA) for yak AQP4 and analyzed structural differences of AQP4 between yak and cattle. We used reverse transcription quantitative polymerase chain reaction and western blot to investigate whether the expression of AQP4 mRNA and protein was different in brain of yak and cattle. In addition, immunohistochemistry was use to analyze the localization and expression of AQP4 in brain of yak and cattle. Results: Immunohistochemical results have shown that AQP4 is expressed in many regions of the yak brain, and both protein and messenger RNA (mRNA) levels are significantly lower than those of low-altitude cattle (Bos taurus). Phylogenetic analysis revealed that yak AQP4 is evolutionarily conserved. Interestingly, a substitution of Ala (cattle) to Ser in position 82, and eight additional amino acid residues composing an α-helix region are present in yak AQP4 protein. These sequence modifications potentially modulate the function of AQP4 in distinct environments. Conclusions: Our findings suggest that AQP4 may have an important role in the resistance to cerebral edema through low expression and maintenance of normal physiological function in the yak brain.

Balanced single-vector co-delivery of VEGF/PDGF-BB improves functional collateralization in chronic cerebral ischemia

The myoblast-mediated delivery of angiogenic genes represents a cell-based approach for targeted induction of therapeutic collateralization. Here, we tested the superiority of myoblast-mediated co-delivery of vascular endothelial growth factor-A (VEGF) together with platelet-derived growth factor-BB (PDGF-BB) on transpial collateralization of an indirect encephalomyosynangiosis (EMS) in a model of chronic cerebral ischemia. Mouse myoblasts expressing a reporter gene alone (empty vector), VEGF, PDGF-BB or VEGF and PDGF-BB through a single bi-cistronic vector (VIP) were implanted into the temporalis muscle of an EMS following permanent ipsilateral internal carotid artery occlusion in adult, male C57BL/6N mice. Over 84 days, myoblast engraftment and gene product expression, hemodynamic impairment, transpial collateralization, angiogenesis, pericyte recruitment and post-ischemic neuroprotection were assessed. By day 42, animals that received PDGF-BB in combination with VEGF (VIP) showed superior hemodynamic recovery, EMS collateralization and ischemic protection with improved pericyte recruitment around the parenchymal vessels and EMS collaterals. Also, supplementation of PDGF-BB resulted in a striking astrocytic activation with intrinsic VEGF mobilization in the cortex below the EMS. Our findings suggest that EMS surgery together with myoblast-mediated co-delivery of VEGF/PDGF-BB may have the potential to serve as a novel treatment strategy for augmentation of collateral flow in the chronically hypoperfused brain.

LncRNA SNHG1 alleviates hypoxia-reoxygenation-induced vascular endothelial cell injury as a competing endogenous RNA through the HIF-1α/VEGF signal pathway

Long noncoding ribonucleic acids (lncRNAs) are critical regulators in various biological processes. In the present study, we aimed to explore whether miR140-3p was involved in the underlying molecular mechanisms of small nucleolar RNA host gene 1 (SNHG1) in myocardial ischemia/reperfusion (I/R) injury. A mouse model of I/R injury and hypoxia-reoxygenation (H/R)-stimulated human umbilical vein endothelial cells (HUVECs) was used in this study. Cell proliferation was detected by MTT. The mRNA and protein levels of vascular endothelial growth factor (VEGF), VE-cadherin, and MMP2 were detected by RT-PCR and western blot, respectively. The angiogenesis was assessed by tube formation assay. Cell migration was assessed using wound-healing assay. Results showed that SNHG1 expression was increased in the cardiac microvasculature of a mouse model of I/R injury and in H/R-stimulated HUVECs. H/R stimulation significantly reduced cell proliferation, tube formation, and cell migration, but increased expression of VEGF, VE-cadherin, and MMP2. SNHG1 upregulation under H/R increased HUVECs proliferation, tube formation, and cell migration, and upregulated expression of VEGF, VE-cadherin, and MMP2, compared with the H/R group. SNHG1 knockdown exhibited the opposite effect. SNHG1 functioned as a competing endogenous RNA (ceRNA) of miR-140-3p. HIF-1α was identified as a target of miR-140-3p. SNHG1 upregulation enhanced cell proliferation, tube formation, and expression of VEGF, VE-cadherin, and MMP2 through HIF-1α/VEGF signaling. This process could be offset by miR-140-3p mimic or VEGF inhibitor. Our results reveal a novel protective function of SNHG1 that furthers understanding of cardiac I/R injury and provides experimental evidence for future therapy.

Association of Age with the Expression of Hypoxia-Inducible Factors HIF-1α, HIF-2α, HIF-3α and VEGF in Lung and Heart of Tibetan Sheep

Simple Summary

The heart and lung play an essential role in physiological homeostasis, especially in a hypoxic environment. The effect of aging on HIF-1α, HIF-2α, HIF-3α and VEGF expression in the heart and lung of Tibetan sheep that were adapted to hypoxia was evaluated in this study. We conclude that HIF-3a and VEGF are important in how the heart responds to hypoxia and that HIF-1a and HIF-2a may help mediate the adaptation by the sheep to hypoxia. The results suggested that the altered expression of these proteins due to hypoxia is regulated at the protein as well as gene levels. The expression of these proteins in alveolar macrophages suggests these cells play an important role in adaption to hypoxia. The research could provide insight into the role of inflammation in response to reduced alveolar PO2, and is useful in understanding how age influences the hypoxia adaption mechanisms of the heart and lung. This may allow a better understanding of chronic mountain sickness that is commonly observed in Tibetan people living at high altitude on the Qinghai-Tibetan plateau.

Abstract

Hypoxia-inducible factors (HIFs) play an important role in mediating the physiological response to low oxygen environments. However, whether the expression of HIFs changes with age is unknown. In the present study, the effect of aging on HIF-1α, HIF-2α, HIF-3α and VEGF expression in the heart and lung of 30 Tibetan sheep that were adapted to hypoxia was evaluated. The 30 sheep were subdivided into groups of 10 animals that were 1, 2 or 6 years of age. Immunohistochemistry for HIF-1α, HIF-2α, HIF-3α and VEGF revealed that the immunostaining intensity of VEGF protein in the heart and lung was significantly higher than the intensity of immunostaining against the HIFs (p < 0.05). HIF-1α and HIF-2α protein translocated into the nucleus of cardiac muscle cells. However, immunostaining for HIF-3α was restricted to the cytoplasm of the myocardial cells. Immunostaining for HIF-1α, HIF-2α, HIF-3α and VEGF was detected within alveolar macrophages. The concentration of HIF-1α and HIF-2α was higher in the lung of 1-year-old than 6-year-old sheep (p < 0.05). In contrast, HIF-3α and VEGF immunostaining was most prominent in the hearts of the oldest sheep. However, when RT-PCR was used to evaluate RNA within the tissues, the expression of all four studied genes was higher in the lung than in the heart in the 1-year-old sheep (p < 0.05). Furthermore, VEGF and HIF-3α gene expression was higher in the heart from 1-year old than 6-year old sheep (p < 0.05). However, in the lung, HIF-1α and HIF-2α gene expression was lower in 1-year old than 6-year old sheep (p < 0.05). We conclude that HIF-3α and VEGF may play be important in how the heart responds to hypoxia. Additionally, HIF-1α and HIF-2α may have a role in the adaptation of the lung to hypoxia. The expression of these proteins in alveolar macrophages suggests a potential role of these cells in the physiological response to hypoxia. These results are useful in understanding how age influences the hypoxia adaption mechanisms of the heart and lung and may help to better understand chronic mountain sickness that is commonly observed in Tibetan people living on the Qinghai-Tibetan plateau.

Regulation by Hsp27/P53 in testis development and sperm apoptosis of male cattle (cattle-yak and yak)

Heat shock protein 27 (Hsp27)/protein 53 (P53) plays an important role in testis development and spermatozoa regulation, but the relationship between Hsp27/P53 and infertility in cattle is unclear. Here, we focus on male cattle-yak and yak to investigate the expression and localization of Hsp27/P53 in testis tissues and to explore the influence of Hsp27/P53 on infertility. In our study, a total of 54 cattle (24 cattle-yak and 30 yak) were examined. The Hsp27 and P53 messenger RNA (mRNA) of cattle-yak were cloned, and amino acid variations in Hsp27 and P53 were found; the variations led to differences in the protein spatial structure compared with yak. We used real-time quantitative polymerase chain reaction and western blot to investigate whether the expression of Hsp27/P53 mRNA and protein was different in cattle-yak and yak. We found that the expression levels of Hsp27/P53 mRNA and protein were different in the testis developmental stages and the highest expression was observed in testicles during adulthood. Moreover, the Hsp27 expression was significantly higher in yak, whereas P53 expression was higher in cattle-yak (p < 0.01). On this basis, we detected the location of Hsp27/P53 in the testis by immunohistochemistry and immunofluorescence. The results demonstrated that Hsp27 was located in spermatogenic cells at different developmental stages and mesenchymal cells of the yak testicles. However, P53 was located in the primary spermatocyte and interstitial cells of the cattle-yak testicles. In summary, our study proved that the expression of Hsp27/P53 differed across the testis developmental stages and the expression of P53 was higher in the testis of cattle-yak, which suggested that the infertility of cattle-yak may be caused by the upregulation of P53.

Chicoric Acid Improves Heart and Blood Responses to Hypobaric Hypoxia in Tibetan Yaks

Yak is a wild bovine species living on the Qinghai Tibet Plateau that demonstrates good adaptability to the hypoxic environment. Chicoric acid, a natural phenolic compound, is known as having anti-oxidant, antiviral, anti-inflammatory and analgesic properties. However, its effect on hypoxia adaptability of yak is still unclear. In this study 40 yaks were selected that were of similar age, parity and weight, and divided into the control group and experimental groups 1, 2, 3, randomly. Results showed that chicoric acid significantly improved RBC, HGB, and WBC. There are significantly beneficial effects to increasing total protein contents ([Formula: see text]): all treatments increased HDL-C contents, and supplementations 100[Formula: see text]mg/h significantly decreased the content of TG on the 60th day ([Formula: see text]). Contents of the serum related enzymes like ALP, GOP and GPT showed varying degrees of change, but no significant differences and the indexes of anti-oxidant capacity (T-AOC and GSH-Px) were significantly improved ([Formula: see text]), but MDA was decreased ([Formula: see text]) under the action of the chicoric acid. Hypoxia-inducible factor in serum such as HIF-2[Formula: see text], EPO, ROS, Fe[Formula: see text] and Tf are all significantly decreased ([Formula: see text]). The myocardial mitochondrial parameters mtDNA, UCP2, PGC1-[Formula: see text], NRF1 and mitochondrial complexes were altered remarkably. Some indicators of glucose metabolism presented variation trends. Taken together, chicoric acid has shown a positive effect on the adaptive ability of yak in high altitude, hypoxic environment in plateau areas. Our findings reported a new potential means to enhance immunity and inflammatory response and improve the anti-oxidant capacity.

Dioxygen and Metabolism; Dangerous Liaisons in Cardiac Function and Disease

The heart must consume a significant amount of energy to sustain its contractile activity. Although the fuel demands are huge, the stock remains very low. Thus, in order to supply its daily needs, the heart must have amazing adaptive abilities, which are dependent on dioxygen availability. However, in myriad cardiovascular diseases, “fuel” depletion and hypoxia are common features, leading cardiomyocytes to favor low-dioxygen-consuming glycolysis rather than oxidation of fatty acids. This metabolic switch makes it challenging to distinguish causes from consequences in cardiac pathologies. Finally, despite the progress achieved in the past few decades, medical treatments have not improved substantially, either. In such a situation, it seems clear that much remains to be learned about cardiac diseases. Therefore, in this review, we will discuss how reconciling dioxygen availability and cardiac metabolic adaptations may contribute to develop full and innovative strategies from bench to bedside.

Cloning of HSP90, expression and localization of HSP70/90 in different tissues including lactating/non-lactating yak (Bos grunniens) breast tissue

The aim of this study is to investigate the expression and localization of HSP70/90 in different tissues and explore the regulation effects of HSP70/90 at lactation period of female yaks. HSP90 mRNA was cloned from the heart samples of female yaks, Quantitative real-time (qRT-PCR), Western blotting (WB), immunohistochemistry and immunofluorescence assays were utilized to analyze the expressions of HSP70/90 mRNA and protein in different tissues. Sequence analysis showed that HSP90 is a conserved molecular chaperone of female yaks. The qRT-PCR, WB results showed that the expressions of HSP70/90 mRNA and protein were significantly different in different tissues, and 3-fold higher expression during the lactation period than the non-lactation period of breast tissue (P < 0.01). Immunohistochemistry and immunofluorescence assays results showed that HSP70/90 were located in the cardiac muscle cells, cerebellar medulla, theca cells lining at the reproductive system, and the mammary epithelia of the breasts. In addition, the expression level of HSP70 was higher than those of HSP90 in all examined tissues. Therefore, our results strongly suggest that the expression and localization of HSP70/90 could provide significant evidence to further research in tissue specific expression, and lactation function of female yaks.

The histological characteristics, age-related thickness change of skin, and expression of the HSPs in the skin during hair cycle in yak (Bos grunniens)

OBJECTIVE

This experiment was conducted to study the histological characteristics, age-related thickness changes, and expression of HSPs in the skin of yak.

METHODS

A total of 20 yaks (10 males and 10 females) were used. Different regions of the normal skin of three different ages (newborn, half-year-old and adult) of yaks were harvested for histological study and thickness measurement. Biopsy samples were taken from the scapula regions of the skin from the same five approximately 1-year-old yaks during the hair cycle (telogen, anagen and catagen). RT-PCR, western blot and immunohistochemistry methods using the mRNA and protein levels were used to detect the expression of HSP27, HSP70 and HSP90. RT-PCR method was used to detect the mRNA expression of CGI-58 and KDF1. The IPP6.0 software was used to analyze the immunohistochemistry and measure the thickness of the skin.

RESULTS

The general histological structure of hairy yak skin was similar to other domestic mammals. The unique features included prominent cutaneous vascular plexuses, underdeveloped sweat glands, a large number of nasolabial glands in the nasolabial plate, and hair follicle groups composed of one primary follicle and several secondary follicles. The skin, epidermis and dermis thickness did vary significantly between different body regions and different ages. The thickness of the skin, epidermis and dermis increased from newborn to adult in yaks. Yak skin thickness decreased from dorsally to ventrally on the trunk. The skin on the lateral surface was thicker than the skin on the medial surface on the limbs. HSP27, HSP70 and HSP90 showed different expression patterns during the hair cycle using RT-PCR, western blot and immunohistochemistry methods. The expression of HSP27 mRNA and protein in the anagen stage was the highest, followed by the catagen stage, and the expression in the telogen stage was the lowest. The expression of HSP70 mRNA and protein in the telogen stage was the highest, followed by the anagen stage, and the expression in the catagen stage was the lowest. The expression of HSP90 mRNA and protein in the anagen stage was the highest, followed by the telogen stage, and the expression in the catagen stage was the lowest. HSPs were mainly expressed in the outer root sheath of hair follicle during the hair cycle, also expressed in epidermis, sebaceous gland and sweat gland in the skin of Yak. The expression of CGI-58 mRNA in the anagen stage was the highest, followed by the catagen stage, and the expression in the telogen stage was the lowest. The expression of KDF1 mRNA in the telogen stage was the highest, followed by the catagen stage, and the expression in the anagen stage was the lowest.

MEANING

In this study, we examined and fully described the histology of normal skin in Yak and measured the skin thickness of different ages and different regions in Yak. These data may be useful to better understand and appreciate the adaptability features of yak skin. Our investigation reports the expression patterns of HSPs in yak skin for the first time. The different expression pattern of HSPs during the hair cycle suggests they may play different roles in yak hair follicle biology.