JAK3: expression and mapping to chromosome 19p12-13.1.
We cloned JAK3, the most recently described member of the JAK family of intracellular tyrosine kinases, from normal human CD34+ RNA. JAK3 is involved in the signal transduction pathways of the IL-2, IL-4, IL7, IL-9, and IL-15 receptors by association with their common gamma-chain (gamma[c]). JAK3 is critical to lymphoid development, as recently established by the linking of mutations in JAK3 to a subgroup of patients with SCID and the generation of JAK3-null mice with severe disruptions in normal lymphocytic development. However, JAK3 expression is not restricted to the lymphocytic compartment of bone marrow but is found in a wide range of tissues of both hematopoietic and non-hematopoietic origin. Northern blot analysis indicates that JAK3 is also expressed in adult placenta, lung, liver, kidney, pancreas, spleen, thymus, ovary, and small intestine. RNAse protection assays and RT-PCR indicate that JAK3 is expressed in a variety of leukemic-derived hematopoietic cell lines with myeloid and/or lymphoid phenotypes. In normal human bone marrow, JAK3 is expressed in the CD34+/lineage- fraction, which is highly enriched in hematopoietic stem/progenitor cells. In addition, we found a splice variant of JAK3 which is formed by the splicing of JAK3 with exon II of the leydig insulin-like (LEY I-L) hormone. RT-PCR and RNAse protection assay analyses indicate that this variant (termed I-JAK3) is normally expressed in almost all hematopoietic and non-hematopoietic tissues shown to express JAK3. Using fluorescence in situ hybridization we have localized JAK3 to 19p12-13.1, the same region of chromosome 19 to which the LEY I-L hormone maps (19p12-13.2).
Safford
M G
MG
Oncology Center, Department of Biology, Johns Hopkins University, Baltimore, Maryland 21287, USA.
Levenstein
M
M
Tsifrina
E
E
Amin
S
S
Hawkins
A L
AL
Griffin
C A
CA
Civin
C I
CI
Small
D
D
D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis; D001483:Base Sequence; D001853:Bone Marrow / Q000276:immunology; D001854:Bone Marrow Cells; D002874:Chromosome Mapping; D002888:Chromosomes, Human, Pair 19; D002999:Clone Cells / Q000276:immunology; D015870:Gene Expression; D014644:Genetic Variation; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D053616:Janus Kinase 3; D008297:Male; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011505:Protein-Tyrosine Kinases / Q000235:genetics*
D018952:Antigens, CD34; D011505:Protein-Tyrosine Kinases; C507933:JAK3 protein, human; D053616:Janus Kinase 3