Tissue-specific mRNA Expression Profiles of Human Solute Carrier Transporter Superfamilies

Abstract

Pairs of forward and reverse primers and TaqMan probes specific to each of 173 human solute carrier (SLC) transporters were prepared. The mRNA expression level of each target transporter was analyzed in total RNA from single and pooled specimens of various human tissues (adrenal gland, bladder, bone marrow, brain, colon, heart, kidney, liver, lung, mammary gland, ovary, pancreas, peripheral leukocytes, placenta, prostate, retina, salivary gland, skeletal muscle, small intestine, smooth muscle, spinal cord, spleen, stomach, testis, thymus, thyroid gland, trachea, and uterus) by real-time reverse transcription PCR using an Applied Biosystems 7500 Fast Real-Time PCR System. Individual differences in the mRNA expression of human SLC transporters in the liver were also evaluated. These newly determined expression profiles were used to study the gene expression in the 28 different human tissues listed above, and tissues with high transcriptional activity for human SLC transporters were identified. These results are expected to be valuable for research concerning the clinical diagnosis of disease.

Phosphate transporters of the SLC20 and SLC34 families

“…This widespread expression pattern is also reflected at the mRNA level of human tissue (Fig 1B) (Nishimura and Naito, 2008). In kidney, expression of both PiT1 and PiT-2 was detected, yet the cellular localization at the apical membrane of proximal tubular epithelia was described only for PiT-2 (Villa-Bellosta et al, 2009).…”

“…In humans mRNA is detected in lungs, testis, salivary gland, thyroid gland, small intestine, liver, mammary gland, uterus but not in renal tissue (Fig 1B) (Nishimura and Naito, 2008).…”

“…The 75kDa protein is localized at the apical membranes of proximal tubule epithelia of juxtamedullary nephrons (Segawa et al, 2002). Like NaPi-IIa, the distribution of mRNA in human tissue is also renal specific (Fig 1B) (Nishimura and Naito, 2008).…”

“…NaPi-IIb has a wider pattern of expression (Hilfiker et al, 1998;Nishimura and Naito, 2008) and its constitutive depletion in mice is lethal (Shibasaki et al, 2009). It is the only SLC34 member present in intestinal microvilli.…”

“…The major site of expression is the renal proximal tubule where the 80-90kDa protein is localized in the microvilli that form the brush border membrane (BBM). In human tissue, significant mRNA expression is detected only in the kidney (Fig 1B) (Nishimura and Naito, 2008). Under normal physiological conditions, the abundance of NaPi-IIa is highest in the S1 proximal tubule segments of juxtamedullary nephrons (Custer M, 1994).…”