Warning: file_get_contents(https://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&id=27338124
&cmd=llinks): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 215
Deprecated: Implicit conversion from float 233.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 233.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 233.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 233.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 233.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 233.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 233.6 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 267.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 267.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 267.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 267.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Deprecated: Implicit conversion from float 267.2 to int loses precision in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 534
Warning: imagejpeg(C:\Inetpub\vhosts\kidney.de\httpdocs\phplern\27338124
.jpg): Failed to open stream: No such file or directory in C:\Inetpub\vhosts\kidney.de\httpdocs\pget.php on line 117 J+Physiol
2016 ; 594
(21
): 6267-6286
Nephropedia Template TP
gab.com Text
Twit Text FOAVip
Twit Text #
English Wikipedia
A novel mutant Na(+) /HCO3(-) cotransporter NBCe1 in a case of
compound-heterozygous inheritance of proximal renal tubular acidosis
#MMPMID27338124
Myers EJ
; Yuan L
; Felmlee MA
; Lin YY
; Jiang Y
; Pei Y
; Wang O
; Li M
; Xing XP
; Marshall A
; Xia WB
; Parker MD
J Physiol
2016[Nov]; 594
(21
): 6267-6286
PMID27338124
show ga
KEY POINTS: The inheritance of two defective alleles of SLC4A4, the gene that
encodes the widely-expressed electrogenic sodium bicarbonate cotransporter NBCe1,
results in the bicarbonate-wasting disease proximal renal tubular acidosis
(pRTA). In the present study, we report the first case of compound-heterozygous
inheritance of pRTA (p.Arg510His/p.Gln913Arg) in an individual with low blood pH,
blindness and neurological signs that resemble transient ischaemic attacks. We
employ fluorescence microscopy on non-polarized (human embryonic kidney) and
polarized (Madin-Darby canine kidney) renal cell lines and electrophysiology on
Xenopus oocytes to characterize the mutant transporters (R510H and Q913R). Both
mutant transporters exhibit enhanced intracellular retention in renal cells, an
observation that probably explains the HCO(3)(-) transport deficit in the
individual. Both mutants retain a close-to-normal per molecule Na(+) /HCO(3)(-)
cotransport activity in Xenopus oocytes, suggesting that they are suitable
candidates for folding-correction therapy. However, Q913R expression is uniquely
associated with a depolarizing, HCO(3)(-) independent, Cl(-) -conductance in
oocytes that could have pathological consequences if expressed in the cells of
patients. ABSTRACT: Proximal renal tubular acidosis (pRTA) is a rare,
recessively-inherited disease characterized by abnormally acidic blood,
blindness, as well as below average height and weight. pRTA is typically
associated with homozygous mutation of the solute carrier 4 family gene SLC4A4.
SLC4A4 encodes the electrogenic sodium bicarbonate cotransporter NBCe1, a
membrane protein that acts to maintain intracellular and plasma pH. We present
the first description of a case of compound-heterozygous inheritance of pRTA. The
individual has inherited two mutations in NBCe1: p.Arg510His (R510H) and
p.Gln913Arg (Q913R), one from each parent. In addition to the usual features of
pRTA, the patient exhibits unusual signs, such as muscle spasms and fever. We
have recreated these mutant transporters for expression in model systems. We find
that both of the mutant proteins exhibit substantial intracellular retention when
expressed in mammalian renal cell lines. When expressed in Xenopus oocytes, we
find that the R510H and Q913R-mutant NBCe1 molecules exhibit apparently normal
Na(+) /HCO(3)(-) cotransport activity but that Q913R is associated with an
unusual HCO(3)(-) independent anion-leak. We conclude that a reduced accumulation
of NBCe1 protein in the basolateral membrane of proximal-tubule epithelia is the
most probable cause of pRTA in this case. We further note that the
Q913R-associated anion-leak could itself be pathogenic if expressed in the plasma
membrane of mammalian cells, compromising the benefit of strategies aiming to
enhance mutant NBCe1 accumulation in the plasma membrane.