Biomedical subjects

K S Korkmaz

Publications and source records attributed to K S Korkmaz.

5 recordsLinked to original sources

PubMed2001

Distinctly different gene structure of KLK4/KLK-L1/prostase/ARM1 compared with other members of the kallikrein family: intracellular localization, alternative cDNA forms, and Regulation by multiple hormones.

The tissue kallikreins (KLKs) form a family of serine proteases that are involved in processing of polypeptide precursors and have important roles in a variety of physiologic and pathological processes. Common features of all tissue kallikrein genes identified to date in various species include a similar genomic organization of five exons, a conserved triad of amino acids for serine protease catalytic activity, and a signal peptide sequence encoded in the first exon. Here, we show that KLK4/KLK-L1/prostase/ARM1 (hereafter called KLK4) is the first significantly divergent member of the kallikrein family. The exon predicted to code for a signal peptide is absent in KLK4, which is likely to affect the function of the encoded protein. Green fluorescent protein (GFP)-tagged KLK4 has a distinct perinuclear localization, suggesting that its primary function is inside the cell, in contrast to the other tissue kallikreins characterized so far that have major extracellular functions. There are at least two differentially spliced, truncated variants of KLK4 that are either exclusively or predominantly localized to the nucleus when labeled with GFP. Furthermore, KLK4 expression is regulated by multiple hormones in prostate cancer cells and is deregulated in the androgen-independent phase of prostate cancer. These findings demonstrate that KLK4 is a unique member of the kallikrein family that may have a role in the progression of prostate cancer.

Alternative Splicing↗

PubMed2000

Full-length cDNA sequence and genomic organization of human NKX3A - alternative forms and regulation by both androgens and estrogens.

NKX3A (NKX3.1) is a recently identified androgen-regulated gene that is largely specific to prostate for expression and likely to code for a homeobox protein. Here we report the full-length mRNA and genomic organization of human NKX3.1. There are at least five different splice variants of NKX3.1 mRNA that result in different open reading frames (ORFs). There is extensive similarity between the human and the mouse NKX3.1 cDNA sequences outside of the ORFs (greater than 60% overall identity), which may be involved in modulating NKX3.1 expression. In addition to its androgen regulation in the prostate cancer cell line LNCaP, we show that NKX3.1 expression is androgen-dependent in the CWR22 prostate cancer xenograft model. Interestingly, NKX3.1 is highly expressed in the androgen-independent derivative CWR22R in the absence of androgens, indicating that it may be deregulated in advanced prostate cancer. Using a Green Fluorescent Protein fusion construct, we show that NKX3.1 is a nuclear protein consistent with its proposed function as a homeobox transcription factor. Furthermore, in addition to androgens, NKX3.1 expression is up-regulated by 17beta-estradiol, but not by progesterone, dexamethasone, or 3,5,3'-triiodothyronine in LNCaP cells. Regulation of NKX3.1 by androgens and 17beta-estradiol in prostate cancer cells and its deregulation in androgen-independent prostate cancer suggest that it may have important regulatory roles during prostate cancer progression.

Alternative Splicing↗

PubMed2000

An efficient procedure for cloning hormone-responsive genes from a specific tissue.

Nuclear receptors form a superfamily of ligand-activated transcription factors. In contrast to the significant advances made in recent years to dissect nuclear receptor structure and their corresponding function, progress has been rather slow in the identification of target genes for nuclear receptors, information that is a prerequisite for understanding hormone action. Here, we describe a simple screening protocol that makes it possible to efficiently and effectively clone hormone-responsive genes that are specific to a tissue of interest. When this procedure was used to clone prostate-specific and androgen-responsive genes, approximately 40% of the clones selected at random represented genes that are known to be androgen regulated and are largely specific to prostate for expression, such as prostate specific antigen (PSA). A further 37% are known to be highly enriched in prostate for expression, but their androgen regulation is yet to be studied. The rest of the clones represented novel genes, expressed sequence tags, or known genes whose possible androgen regulation has not yet been assessed. This screening scheme can be applied to any hormone/ligand to clone differentially expressed genes specific to a tissue of interest. Identification of such genes and their characterization should greatly facilitate understanding hormone action in normal and pathological conditions.

Androgens↗

PubMedDate not supplied

Two brothers with a 7.0 kb gene deletion associated with isolated growth hormone deficiency type 1A.

Familial growth hormone deficiency type 1A is an autosomal recessive disease, caused by various homogenous deletions of both alleles of growth hormone gene 1 (hGH1). The hGH1 gene deletion is an event occurring between the 5' and the 3' flanking regions by unequal recombination, which causes a deletion in the hGH1 gene, mostly of 6.7 kb and rarely 7.6 or 7.0 kb in size. Two brothers diagnosed with GH deficiency syndrome were sent to our hospital for further evaluation. DNA samples of the probands and controls were amplified by PCR; restriction endonuclease analysis was done with Sma I enzyme and the patterns were evaluated. Gel electrophoresis results showed that the two brothers had a 7.0 kb deletion. These are the third and fourth cases reported with a 7.0 kb deletion. Both patients responded well to replacement therapy and did not develop antibodies against rGH. No other relatives presented with macro deletions in the hGH1 gene.

Child↗

PubMedDate not supplied

A Turkish family with 6.7 Kb deletion associated with isolated growth hormone deficiency type 1A.

Familial growth hormone deficiency type 1A is an autosomal recessive disease caused by homogenous deletions of both alleles of growth hormone gene 1 (hGH1) in various patterns. The hGH1 gene deletion is an event that probably occurs between the 5' and 3' flanking regions by unequal recombination, and results in deletion of the hGH1 gene in different patterns. Deletions are mostly 6.7 kb and rarely 7.0 kb, 7.6 kb and 45 kb in size. A four-year-old girl diagnosed with growth hormone deficiency syndrome was send to us for further evaluation. DNA samples of the patient, her parents and controls were amplified by polymerase chain reaction (PCR); furthermore, restriction endonuclease analysis was done with Sma I enzyme and the patterns were evaluated. Our gel electrophoresis results show that the gene deletion pattern of the patient represents a homogenous 6.7 kb deletion, while her parents had a heterogeneous 6.7 kb deletion pattern.

Child, Preschool↗