Genomic organization of the genes for human and mouse CC chemokine LEC.

Liver-expressed chemokine (LEC) is a CC chemokine that is selectively expressed in the liver. We report here the structures of the human and mouse genes for LEC. The human LEC gene (SCYA16) was isolated from a bacterial artificial chromosome (BAC) clone that also contained CC chemokine genes for MPIF-1/Ckbeta8, HCC-2/Lkn-1/MIP-5/MIP-1delta, and HCC-1. The LEC gene is approximately 5.0 kb in length and has a three-exon and two-intron structure common to most CC chemokine genes. However, the promoter region is devoid of a typical TATA box, and transcription initiates at multiple sites. The gene for CC chemokine HCC-1, which is most similar to LEC, is located approximately 2.2 kb upstream from the 5' end of the LEC gene in a head-to-tail fashion. The mouse DNA fragment that hybridized with the human LEC cDNA was isolated from a BAC clone that also contained the CC chemokine genes for C10, MRP-2/CCF18/MIP-1gamma, and RANTES. Sequence analysis revealed that the isolated gene does not encode a functional chemokine because of deletions, insertions, and base changes. Southern blot analysis revealed that the sequence isolated from the BAC clone was the only one hybridizing with human LEC cDNA in the mouse genome. Therefore, mice may have only an LEC pseudogene.

[Degradation of the parathyroid hormone in the kidney and liver (author's transl)].

The cleavage of the parathyroid hormone has been reported to take place in various peripheral tissues, especially in the kidney and liver. In order to claify the mechanism of such a degradation, bovine PTH (bPTH 1--84) and its synthetic N-terminal peptide (bPTH 1--34) labelled with 125I by the chroramine-T method (125I-bPTH 1--84) and (125I-bPTH 1--34) or labelled with horseradish peroxidase Pox-125I-bPTH 1--84 and Pox 125I-bPTH 1 34) were used to study the disappearance from the blood stream and degradation and retension in the kidney and liver after intravenous injections in male Wiastar rats, weighing approximately 200g. Degradation of PTH was also studied in vitro, using isolated cells and a homogenate of the kidney and liver. PTH labeled with 125I and Pox was more readily degraded by the kidney than PTH labelled with 125I alone, but the opposite was found in the degradation by the liver. Isolated intact kidney cells degraded PTH less efficiently than the homogenate, but the isolated intact liver cells degraded PTH more efficiently than the homogenate, indicating the prominence of an intracellular mechanism of degradation in the kidney and an extracellular mechanism in the liver.