Berberine-induced Inactivation of Signal Transducer and Activator of Transcription 5 Signaling Promotes Male-specific Expression of a Bile Acid Uptake Transporter.

Sodium-taurocholate co-transporting polypeptide (Ntcp/NTCP) is the major uptake transporter of bile salts in mouse and human livers. In certain diseases, including endotoxemia, cholestasis, diabetes, and hepatocarcinoma, Ntcp/NTCP expression is markedly reduced, which interferes with enterohepatic circulation of bile salts, impairing the absorption of lipophilic compounds. Therefore, normal Ntcp/NTCP expression in the liver is physiologically important. Berberine is an herbal medicine used historically to improve liver function and has recently been shown to repress STAT signaling. However, berberine effects on Ntcp/NTCP expression are unknown, prompting use to investigate this possible connection. Our results showed that berberine dose-dependently increased Ntcp expression in male mouse liver and decreased taurocholic acid levels in serum but increased them in the liver. In mouse and human hepatoma cells, berberine induced Ntcp/NTCP mRNA and protein expression and increased cellular uptake of [3H] taurocholate. Mechanistically, berberine decreased nuclear protein levels of phospho-JAK2 and phospho-STAT5, thus disrupting the JAK2-STAT5 signaling. Moreover, berberine stimulated luciferase reporter expression from the mouse Ntcp promoter when one putative STAT5 response element (RE) (-1137 bp) was deleted and from the human NTCP promoter when three putative STAT5REs (-2898, -2164, and -691 bp) were deleted. Chromatin immunoprecipitation demonstrated that berberine decreased binding of phospho-STAT5 protein to the-2164 and -691 bp STAT5REs in the human NTCP promoter. In summary, berberine-disrupted STAT5 signaling promoted mouse and human Ntcp/NTCP expression, resulting in enhanced bile acid uptake. Therefore, berberine may be a therapeutic candidate compound for maintaining bile acid homeostasis.

Expression of sodium-dependent dicarboxylate transporter 1 (NaDC1/SLC13A2) in normal and neoplastic human kidney.

Regulated dicarboxylate transport is critical for acid-base homeostasis, prevention of calcium nephrolithiasis, regulation of collecting duct sodium chloride transport, and the regulation of blood pressure. Although luminal dicarboxylate reabsorption via NaDC1 (SLC13A2) is believed to be the primary mechanism regulating renal dicarboxylate transport, the specific localization of NaDC1 in the human kidney is currently unknown. This study's purpose was to determine NaDC1's expression in normal and neoplastic human kidneys. Immunoblot analysis demonstrated NaDC1 expression with an apparent molecular weight of ~61 kDa. Immunohistochemistry showed apical NaDC1 immunolabel in the proximal tubule of normal human kidney tissue; well-preserved proximal tubule brush border was clearly labeled. Apical NaDC1 expression was evident throughout the entire proximal tubule, including the initial proximal convoluted tubule, as identified by origination from the glomerular tuft, and extending through the terminal of the proximal tubule, the proximal straight tubule in the outer medulla. We confirmed proximal tubule localization by colocalization with the proximal tubule specific protein, NBCe1. NaDC1 immunolabel was not detected other than in the proximal tubule. In addition, NaDC1 immunolabel was not detected in tumors of presumed proximal tubule origin, clear cell and papillary renal cell carcinoma, or in tumors of nonproximal tubule origin, oncocytoma and chromophobe carcinoma. In summary, 1) in the human kidney, apical NaDC1 immunolabel is present throughout the entire proximal tubule, and is not detectable in other renal cells; and 2) NaDC1 immunolabel is not present in renal tumors. These studies provide important information regarding NaDC1's role in human dicarboxylate metabolism.

Hepatitis B virus (HBV) receptors: Deficiency in tumor results in scant HBV infection and overexpression in peritumor leads to higher recurrence risk.

Hepatitis B virus (HBV) infection is a risk factor for hepatocarcinogenesis and recurrence. Here, we sought to characterize intratumoral and peritumoral expression of HBsAg and its specific receptors in HBsAg-positive hepatocellular carcinoma (HCC) patients and further examined their correlation with the recurrence-free survival (RFS). HCC tissue and adjacent normal tissue specimens were acquired from HBsAg-positive patients. The presence of HBsAg and receptors, as well as hepatic progenitor cells (HPCs) were detected by tissue microassay and immunohistochemistry. Necroinflammatory activity was evaluated by HE staining. The mean IOD of HBsAg and HBV DNA in the intratumoral tissues was markedly lower than that in the peritumoral tissues (P < 0.001). Pearson correlation analysis further showed a significant correlation between the expression of HBsAg and NTCP (r = 0.461, P < 0.001) or ASGPR (r = 0.506, P < 0.001) in peritumoral tissues. And the peritumoral HBsAg and receptors presented a positive association with necroinflammatory activity (P < 0.05). Inflammation induced by HBV infection presented a positive association with HPCs activation (P < 0.05). Additionally, due to lack of HBV receptors, HPCs was not preferentially infected with HBV, but activated HPCs had a significant correlation with HBsAg expression in peritumoral tissues, and the peritumoral HPCs activation was associated with RFS of HCC patients, therefore, the overexpression of HBsAg and receptors in peritumor were also with higher recurrence risk (P < 0.05). In conclusion, lack of HBV receptors resulted in scant HBV infection in tumor cells, and overexpression of HBsAg and receptors in peritumor was strongly associated with higher recurrence risk in HCC patients.

An integrative study of the genetic, social and environmental determinants of chronic kidney disease characterized by tubulointerstitial damages in the North Central Region of Sri Lanka.

OBJECTIVES: Previous investigations on chronic kidney disease of unknown etiology characterized by tubulointerstitial damages (CKDu) in the North Central Region (NCR) of Sri Lanka have supported the involvement of social, environmental and genetic factors in its pathogenesis. METHODS: We conducted a social-environmental-and-genetic epidemiology study on a male population in NCR to investigate the genetic and environmental contributors. We recruited 311 case-series patients and 504 control candidates. Of the 504 control candidates, 218 (43%) were eliminated because of the presence of hypertension, proteinuria, high HbA1c, high serum creatinine or high alpha-1 microglobulin in urine. RESULTS AND DISCUSSION: None of 18 metals measured (µg//) in urine, including Cd, As and Pb, showed significantly higher concentrations in cases compared with controls. As speciation results showed that 75-80% of total urinary As was in the form of arsenobetaine, which is non-toxic to humans. None of the metal concentrations in drinking water samples exceeded guideline values. A genome-wide association study (GWAS) was conducted to determine the genetic contributors. The GWAS yielded a genome-wide significant association with CKDu for a single nucleotide polymorphism (SNP; rs6066043; p=5.23 × 10(-9) in quantitative trait locus analysis; p=3.73 × 10(-9) in dichotomous analysis) in SLC13A3 (sodium-dependent dicarboxylate transporter member 3). The population attributable fraction and odds ratio for this SNP were 50% and 2.13. Genetic susceptibility was identified as the major risk factor for CKDu. However, 43% of the apparently healthy male population suffers from non-communicable diseases, suggesting their possible influence on CKDu progression.

Distribution of SLC10A4, a synaptic vesicle protein in the human brain, and the association of this protein with Alzheimer's disease-related neuronal degeneration.

Member 4 of the sodium/bile acid co-transporter family of proteins (SLC10A4) was discovered as a synaptic vesicle protein. The distribution of Slc10a4 protein in the brain has only so far been assessed in adult rats. Here, we assessed the regional distribution of SLC10A4 in aged human brain by immunohistochemistry. The protein was ubiquitously expressed, particularly in the cholinergic and monoaminergic neurons and in the lateral geniculate body. The protein expression was not influenced by the postmortem delay or fixation time. Synaptic alterations are reported to be seen in Alzheimer's disease (AD) and the suggested function of SLC10A4 as a vesicular transporter for cholinergic neurotransmitters proposes a link between this protein and AD. With increased severity of AD-related pathology, depletion of SLC10A4 expression was noted in the transentorhinal cortex. Intriguingly, in the most severely affected cases (Braak V), two patterns were noted, i.e., those with severe depletion of SLC10A4 and those with numerous neurons displaying SLC10A4. In conclusion, assessment of the expression of SLC10A4 by means of immunohistochemistry is feasible. The observed depletion of SLC10A4 with increase in the severity of AD-related neuronal degeneration is interesting and the observation that some subjects in Braak V displayed none and some displayed numerous SLC10A4 immunoreactive neurons is intriguing. Assessment of the SLC10A4 protein in neurodegenerative diseases or diseases affecting lateral geniculate body should be carried out to investigate whether alterations in the expression of SLC10A4 in synaptic vesicles might be used as a marker of transmitter deficits (cholinergic, monoaminorgic) or other synaptic pathology.

Absolute measurement of species differences in sodium taurocholate cotransporting polypeptide (NTCP/Ntcp) and its modulation in cultured hepatocytes.

Species differences among membrane transporters can be remarkable and difficult to properly assess by conventional methods. Herein, we employed the first use of stable isotope labeling in mammals or stable isotope-labeled peptides combined with mass spectrometry to identify species differences in sodium taurocholate cotransporting polypeptide (NTCP/Ntcp) protein expression in liver tissue and to characterize the modulation of protein expression in sandwich-cultured human (SCHH) and rat hepatocytes (SCRH). The lower limit of quantification was established to be 5 fmol on column with a standard curve that was linear up to 2000 fmol. The accuracy and precision were evaluated with three quality control samples and known amounts of synthetic proteotypic peptides that were spiked into the membrane protein extracts. The overall relative error and coefficient of variation were less than 10%. The expression of Ntcp in mouse and rat was significant higher than that in human (five-fold) and monkey (two-fold) and ranked as mouse > rat >> monkey > human. In the cultured hepatocytes, although significant downregulation of Ntcp expression in SCRH at day 5 after the culture was detected, NTCP expression in SCHH was comparable to the suspension hepatocytes. The results suggested that NTCP/Ntcp modulation in cultured hepatocytes is species specific.

Characterization of hepatobiliary organic anion transporters in Long-Evans Cinnamon rats.

The liver plays important roles in the detoxification of xenobiotics. Hepatobiliary transporters contribute to hepatic uptake and efflux processes of xenobiotecs. Expressions of these transporters may be modulated under the condition of hepatic failure. Long-Evans Cinnamon (LEC) rats provide a pertinent model for basic and clinical studies on hepatitis. However, only a few reports describing the properties of hepatobiliary transporters in LEC rats have appeared in the literature. We investigated the expression levels of hepatobiliary transporters in LEC rats by real-time RT-PCR. We found that hepatic expressions of three sinusoidal organic anion transporters, Ntcp, Oatp1a1 and Oatp1a4, were decreased in LEC rats. However, no significant difference of the expressions of Mrp2 and Bsep, organic anion transporters located on canalicular membrane, were found between Wistar rats and LEC rats.

Four-dimensional imaging of filter-grown polarized epithelial cells.

Understanding how epithelial cells generate and maintain polarity and function requires live cell imaging. In order for cells to become fully polarized, it is necessary to grow them on a permeable membrane filter; however, the translucent filter obstructs the microscope light path required for quantitative live cell imaging. Alternatively, the membrane filter may be excised but this eliminates selective access to apical and basolateral surfaces. Conversely, epithelial cells cultured directly on glass exhibit different phenotypes and functions from filter grown cells. Here, we describe a new method for culturing polarized epithelial cells on a Transwell filter insert that allows superior live cell imaging with spatial and temporal image resolution previously unachievable using conventional methods. Cells were cultured on the underside of a filter support. Epithelial cells grown in this inverted configuration exhibit a fully polarized architecture, including the presence of functional tight junctions. This new culturing system permits four-dimensional (three spatial dimension over time) imaging of endosome and Golgi apparatus dynamics, and permits selective manipulation of the apical and basolateral surfaces. This new technique has wide applicability for visualization and manipulation of polarized epithelial cells.

Immunohistochemical localization of sodium-dependent L-ascorbic acid transporter 1 protein in rat kidney.

Recently, two L-ascorbic acid transporters were identified; sodium-dependent vitamin C transporter (SVCT) 1 and SVCT2. The previous study suggested that SVCT protein might be present on the apical membrane in the straight segment (S3) of proximal tubule. In the present study, SVCT1 immunoreactivity (IR) was observed in the brush border of proximal straight tubules in the medullary ray of renal cortex and the outer stripe of outer medulla, while SVCT2 IR was not localized in any region of the kidney. Since the mechanism of VC reabsorption in the kidney has not been fully elucidated up to the present time, it is meaningful to demonstrate the exact cellular distribution of SVCT protein in the kidney.

[The change of human Na+/dicarboxylate co-transporter 1 expression in the kidney and its relationship with pathogenesis of nephrolithiasis].

OBJECTIVE: To study the change of Na+/dicarboxylate co-transporter 1 expression in the kidney and its relationship with nephrolithiasis. METHODS: 50 volunteers and 85 patients with nephrolithiasis were divided into 3 groups: control, nephrolithiasis with normal urine citrate, and nephrolithiasis with hypocitraturia. The expression of hNaDC1 mRNA in kidney was determined by RT-PCR or Northern blotting, the change of hNaDC1 protein abundance were measured by immunohistochemical staining with anti-hNaDC1 antibody among part of these patients and volunteers. The plasma and urinary biochemical parameters, such as citrate, oxalate, uric acid and calcium etc., were analyzed by routine chemical methods. RESULTS: The recurrence rate of nephrolithiasis in the group of patients with hypocitraturia was 36.1%, significantly higher than the recurrence rate of 16.3% in the group of patients with normal urine citrate (P < 0.01). hNaDC1 was expressed in the normal kidney, localized in the striated border of renal proximal tubule. However, it was expressed highly in the kidneys of patients with hypocitraturia. The ratio hNaDC1 mRNA/18sRNA in the patients with hypocitraturia was 0.65 +/- 0.21, significantly higher than that in the controls (0.36 +/- 0.11, P < 0.01). The ratio hNaDC1 mRNA/18sRNA in the patients with normal urine citrate was not significantly different from that in the controls (P > 0.05). The urine pH and urine sodium were significantly lower in the patients with hypocitraturia than in the other two groups. The levels of urine calcium and urine oxalate were significantly higher in the patients with hypocitraturia than in the controls, and were not different from those in the patients with normal urine citrate. CONCLUSION: The upregulation of hNaDC1 mRNA and protein abundance in the kidney may be an important cause of hypocitraturia, which might be related with the occurrence and recurrence of nephrolithiasis.