Implications of endoplasmic reticulum stress and beta-cell loss in immunodeficient diabetic NRG-Akita mice for understanding monogenic diabetes.

BACKGROUND: Immunodeficient mice models have become increasingly important as in vivo models engrafted with human cells or tissues for research. The NOD-Rag1null Ins2Akita Il2rnull (NRG Akita) mice is a model combined with immunodeficient NRG and monogenic diabetes Akita mice that develop spontaneous hyperglycemia with progressive loss of pancreatic insulin-producing beta-cells with age. This model is one of the monogenic diabetic models, which has been providing a powerful platform for transplantation experiments of stem cells-generated human ß-cells. This research aimed to provide insights into the mechanisms underlying this monogenic diabetes, which remains incompletely understood. METHODS: Histological and immunofluorescence analyses were conducted on endocrine pancreatic islets to compare NRG wild-type (Wt) controls with NRG-Akita mice. Our investigation focused on assessing the expression of endocrine hormones, transcription factors, proliferation, ER stress, and apoptosis. RESULTS: Histological analyses on NRG-Akita mice revealed smaller islets at 6-weeks-old, due to fewer ß-cells in the islets, compared to NRG-Wt controls, which further progressed with age. The proliferation rate decreased, and apoptosis was abundant in ß-cells in NRG Akita mice. Interestingly, our mechanistic analyses revealed that ß-cells in NRG-Akita mice progressively accumulated the endoplasmic reticulum (ER) stresses, leading to a decreased expression of pivotal ß-cell transcriptional factor PDX1. CONCLUSIONS: Altogether, our mechanistic insight into ß-cell loss in this model could shed light on essential links between ER stress, proliferation, and cell identity, which might open the door to new therapeutic strategies for various diseases since ER stress is one of the most common features not only in diabetes but also in other degenerative diseases.

Heart ventricles of the dromedary camel (Camelus dromedarius): new insights from sectional anatomy, 3D computed tomography, and morphometry.

BACKGROUND: Dromedary camel heart morphology is a crucial research topic with clinical applications. The study aims to understand the dromedary camel anatomy, morphology, and architecture of the ventricular mass. RESULTS: Sagittal and transverse gross sections were compared to sagittal, transverse, and 3D render volume reconstruction computed tomography (CT) scans. The subepicardial fat, which covered the heart base, the coronary groove (sulcus coronarius), the left longitudinal interventricular groove (sulcus interventricularis paraconalis), and the right longitudinal interventricular groove (sulcus interventricularis subsinuosus), had a relatively low density with a homogeneous appearance in the 3D render volume CT. The pericardium in the color cardiac window was identified better than the black and white window (ghost). Transverse and sagittal CT scans demonstrated the internal structures of the heart, including the right atrioventricular orifice (ostium atrioventriculare dextrum), right atrioventricular orifice (ostium atrioventriculare sinistrum), and aortic orifice (ostium aortae), chordae tendineae, the cusps of the valves (cuspis valvae), and the papillary muscles (musculi papillares). The papillary muscle (musculi papillares) was presented with a more moderate density than the rest of the heart, and the cusps of the valves (cuspis valvae) had a lower density. The ventricular wall (margo ventricularis) exhibited different densities: the outer part was hyperdense, while the inner part was hypodense. The thicknesses of the ventricular mural wall and the interventricular septum (septum atrioventriculare) were highest at the midpoint of the ventricular mass, and the lowest value was present toward the apical part. The coronary groove (sulcus coronarius) circumference measured 51.14 ± 0.72 cm, and the fat in the coronary groove (sulcus coronarius) (56 ± 6.55 cm2) represented 28.7% of the total cross-sectional area. CONCLUSION: The current study provided more information about ventricular mass measurements by gross and CT analysis on the heart, which provides a valuable guide for future cardiac CT investigations in camels in vivo.

Calbindin Has a Potential Spatiotemporal Correlation with Proliferation and Apoptosis in the Postnatal Rat Kidney.

The protein calbindin-D28k modulates calcium reabsorption in the kidney. Here, we aimed to study the influence of proliferation and apoptosis in different compartments of the kidney on the developmental function of calbindin. Using immunohistochemistry, we investigated the postnatal development of rats' kidneys by using calbindin, proliferative cell nuclear antigen (PCNA), and apoptotic single-stranded DNA (ssDNA). In the neonatal stage (1-day and 1-week-old rats), calbindin showed a positive reaction in the distal convoluted tubule (DCT), a short nephron segment between the macula densa, collecting ducts, and tubules. Moreover, the localization of calbindin was restricted to immature nephrons and mesenchymal tissues. Furthermore, PCNA immunoreactivity was moderate in early-developed podocytes with no reactivity in other renal tubules. The ssDNA immunoreactivity was moderate in the undifferentiated nephron. Then, in the mature stage (3 and 6 weeks old), there was an intense calbindin reaction in DCT but a moderate reaction to PCNA and ssDNA in podocytes. A more intense calbindin reactivity was found in the adult stage (2- and 3-month-old rats) in DCT and collecting tubules. Therefore, in this study, calbindin localization showed an inverse relationship with PCNA and ssDNA of the nephron compartments, which might reflect the efficiency of bone-building and muscle contraction during animal development.

Kruppel-like factor 4 regulates matrix metalloproteinase and aggrecanase gene expression in chondrocytes.

Kruppel-like factor 4 (KLF4) is a zinc finger transcription factor that plays crucial roles during the development and maintenance of multiple organs. We and others have previously shown that KLF4 is involved in bone modeling and remodeling but roles played by KLF4 during skeletogenesis are still not fully understood. Here, we show that KLF4 is expressed in the epiphyseal growth plate and articular chondrocytes. Most articular chondrocytes expressed KLF4 in embryos but it localized only in a subset of superficial zone cells in postnatal mice. When KLF4 was overexpressed in chondrocytes in vitro, it severely repressed chondrocytic gene expressions. Global gene expression profiling of KLF4-transduced chondrocytes revealed matrix degrading proteinases of the matrix metalloproteinase and disintegrin and metalloproteinase with thrombospondin-1 domain families within the group of upregulated genes. Proteinase induction by KLF4 was alleviated by Trichostatin A treatment suggesting the possible involvement of epigenetic mechanisms on proteinase induction by KLF4. These results indicate the possible involvement of KLF4 in physiological and pathological aspects during cartilage development and maintenance.

Fate mapping of Trps1 daughter cells during cardiac development using novel Trps1-Cre mice.

Tricho-rhino-phalangeal syndrome (TRPS) is a rare congenital disorder that is characterized by abnormal hair growth and skeletal deformities. These result in sparse hair, short stature, and early onset of joint problems. Recent reports have shown that a relatively high proportion of patients with TRPS exhibit a broad range of congenital heart defects. To determine the regulation of Trps1 transcription in vivo, we generated novel transgenic mice, which expressed Cre recombinase under the murine Trps1 proximal promoter sequence (Trps1-Cre). We crossed these mice with Cre reporter mice to identify Trps1 daughter cells. Labeled cells were observed in the appendicular joint tissue, dermal papilla of the hair follicles, cardiac valves, aortic sinus, atrial walls, and the interventricular septum. In situ analysis showed restricted Trps1 expression, which was observed in endocardial cushions of the outflow tract, and in leaflets of all mature cardiac valves. These results suggest that the Trps1 proximal promoter sequence contains some of the tissue-specific Trps1 regulatory region. Further, our findings partially explain why patients with TRPS show a broad range of congenital cardiac defects, although Trps1 expression is observed in a more restricted fashion. genesis 54:379-388, 2016. © 2016 Wiley Periodicals, Inc.

Morphological variations of the vallate papillae in some mammalian species.

The morpho-structural characteristics of the vallate papillae of the tongue of rat, dog, donkey and buffalo were investigated by macroscopy and their microstructure by light and scanning electron microscopy (SEM). The numbers of vallate papillae varied among the different species. In rat, a single vallate papilla surrounded by incomplete groove and an annular fold was observed. Taste buds were detected along the entire length of the medial and lateral groove epithelium, but not in the papillary dome. In dog, some papillae lacking the annular pad had irregular ridges and grooves toward the center of the papillary surface, while other papillae had small secondary papillary grooves arising from the center of the papilla. Taste buds were located in the medial and lateral epithelium of both primary and secondary grooves as well as in the dome epithelium. In donkey, two papillae were frequently observed around the midline of the tongue root, and an additional papilla was found occasionally in the middle and associated with secondary papilla. In buffalo, several papillae were relatively small and variable in shape. With SEM, small ridges and grooves were found in the papillae of donkey and buffalo. In both species, taste buds were constantly observed along the medial wall epithelium, but no taste buds were found in the lateral wall. We conclude that the vallate papillae exhibited peculiar characteristics, which are species specific and might have a correlation with the variable feeding habits among these animals.