Flavia F. Jung
Harvard University
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Featured researches published by Flavia F. Jung.
American Journal of Physiology-renal Physiology | 1999
Julie R. Ingelfinger; Flavia F. Jung; Daniel Diamant; Liam Haveran; Edwin Lee; Andrew S. Brem; Shiow-Shih Tang
The renal proximal tubule (PT) is a major site for a complete tissue renin-angiotensin system (RAS) and produces endogenous angiotensin II (ANG II). The present studies demonstrate autocrine RAS feedback in a line of origin-defective SV40 plasmid transformed immortalized rat PT cells (IRPTC) designated as line 93-p-2-1, which are highly differentiated and express all RAS components. Receptor competition assays and Southern blot following RT-PCR demonstrated that these IRPTC express AT1 and AT2 angiotensin receptor subtypes. Autocrine RAS feedback was examined following exposure to ANG II (10-8 M), and it was noted that angiotensinogen mRNA increases significantly by 1 h and remains elevated through 24 h. The AT1 blocker losartan prevents this increase. Moreover, ANG II upregulates expression of ANG II receptor mRNA (both AT1 and AT2). Thus the present studies demonstrate positive ANG II feedback with angiotensinogen and ANG II receptors in PTC, suggesting that the main site of such intrarenal feedback in vivo is within PT. ANG II secreted by line 93-p-2-1 is increased by isoproterenol, suggesting β-adrenergic regulation in IRPTC.
American Journal of Physiology-renal Physiology | 2009
Richard Bouley; Zaira Palomino; Shiow-Shih Tang; Paula Nunes; Hiroyuki Kobori; Hua A. Lu; Winnie W. C. Shum; Ivan Sabolić; Dennis Brown; Julie R. Ingelfinger; Flavia F. Jung
Aquaporin 1 (AQP1) is the major water channel in the renal proximal tubule (PT) and thin descending limb of Henle, but its regulation remains elusive. Here, we investigated the effect of ANG II, a key mediator of body water homeostasis, on AQP1 expression in immortalized rat proximal tubule cells (IRPTC) and rat kidney. Real-time PCR on IRPTC exposed to ANG II for 12 h revealed a biphasic effect AQP1 mRNA increased dose dependently in response to 10(-12) to 10(-8) M ANG II but decreased by 50% with 10(-7) M ANG II. The twofold increase of AQP1 mRNA in the presence of 10(-8) M ANG II was abolished by the AT(1) receptor blocker losartan. Hypertonicity due to either NaCl or mannitol also upregulated AQP1 mRNA by three- and twofold, respectively. Immunocytochemistry and Western blotting revealed a two- to threefold increase in AQP1 protein expression in IRPTC exposed concomitantly to ANG II (10(-8)M) and hypertonic medium (either NaCl or mannitol), indicating that these stimuli were not additive. Three-dimensional reconstruction of confocal images suggested that AQP1 expression was increased by ANG II in both the apical and basolateral poles of IRPTC. In vivo studies showed that short-term ANG II infusion had a diuretic effect, while this effect was attenuated after several days of ANG II infusion. After 10 days, we observed a twofold increase in AQP1 expression in the PT and thin descending limb of Henle of ANG II-infused rats that was abolished when rats were treated with the selective AT(1)-receptor antagonist olmesartan. Thus ANG II increases AQP1 expression in vitro and in vivo via direct interaction with the AT(1) receptor, providing an important regulatory mechanism to link PT water reabsorption to body fluid homeostasis via the renin-angiotensin system.
Pediatric Nephrology | 1993
Flavia F. Jung; Boutros Bouyounes; Raquel Barrio; Shiow-Shih Tang; Daniel Diamant; Julie R. Ingelfinger
Angiotensin converting enzyme (ACE) has multiple effects both as the enzyme which cleaves angiotensin II from angiotensin I and as that which breaks down bradykinin. The present study examines ACE mRNA and protein expression in the rat kidney during development. Changes in distribution and expression during development are consistent with suggestions that the renin angiotensin system is important in growth modulation, vascular development and regulation, and protein reabsorption.
Pediatric Research | 1996
Julie R. Ingelfinger; Liam Haveran; Dan Diamant; Flavia F. Jung; Shiow-Shih Tang
ANGIOTENSIN II (ANG II) MODULATES RESPONSE TO OXIDANT INJURY IN IMMORTALIZED RAT PROXIMAL TUBULE CELLS (IRPTC). † 2157
American Journal of Physiology-renal Physiology | 1993
Sharon Anderson; Flavia F. Jung; Julie R. Ingelfinger
American Journal of Physiology | 1995
Shiow-Shih Tang; Flavia F. Jung; Daniel Diamant; Dennis Brown; David R. Bachinsky; P. Hellman; Julie R. Ingelfinger
Journal of The American Society of Nephrology | 1995
Flavia F. Jung; T M Kennefick; Julie R. Ingelfinger; J P Vora; Stephen R. Anderson
Kidney International | 1998
Flavia F. Jung; David R. Bachinsky; Shiow-Shih Tang; Gang Zheng; Daniel Diamant; Liam Haveran; Robert T. McCluskey; Julie R. Ingelfinger
Pediatrics in Review | 1993
Flavia F. Jung; Julie R. Ingelfinger
Experimental Nephrology | 1994
Shiow-Shih Tang; Flavia F. Jung; Daniel Diamant; Julie R. Ingelfinger