The mTORC1/4E-BP pathway coordinates hemoglobin production with L-leucine availability

Amino acid uptake in erythropoiesis

Erythroblasts produce huge amounts of hemoglobin, for which they must incorporate vast stores of iron and amino acids. In the 14 April issue of Science Signaling, Chung et al. describe the complex mechanism linking neutral amino acid uptake to hemoglobin production in these hungry cells.

L-type amino acid transport and cancer: targeting the mTORC1 pathway to inhibit neoplasia

The L-type amino acid transporter (LAT) family are Na(+)-independent transporters, which deliver neutral amino acids into cells. The four LATs, LAT1 (SLC7A5), LAT2 (SLC7A8), LAT3 (SLC43A1) and LAT4 (SLC43A2), are responsible for the majority of cellular leucine uptake. They show increased expression in many cancers, and are critical for control of protein translation and cell growth through the mTORC1 pathway. The increased transporter expression observed in cancers is regulated by transcriptional pathways such as hormone receptors, c-myc and nutrient starvation responses. We review the expression and function of the LAT family in cancer, as well as the recent development of specific inhibitors targeting LAT1 or LAT3. These LAT family inhibitors may be useful adjuvant therapeutics in multiple cancers.