Lhx9: A Novel LIM-Homeodomain Gene Expressed in the Developing Forebrain

Abstract

A novel LIM-homeodomain gene, Lhx9, was isolated by degenerate RT-PCR followed by mouse embryonic library screening. Lhx9 cDNA encodes a protein that is most closely related to Drosophila apterous and rodent Lhx2 proteins. The Lhx9 spatiotemporal pattern of expression during embryogenesis was similar but distinct from Lhx2. Highest expression levels were found in the diencephalon, telencephalic vesicles, and dorsal mesencephalon. Domains of expression respected the proposed neuromeric boundaries (). Lhx9 was also expressed in the spinal cord, forelimb and hindlimb mesenchyme, and urogenital system. Although Lhx9 expression was sustained in diencephalon and mesencephalon from embryonic day 10.5 (E10.5) to postnatal stages, it was transient in the future cerebral cortex, where it was turned off between E14.5 and E16.5. Lhx9 expression was highest if not exclusively located (depending on the region of interest) in the intermediate and mantle zones, as opposed to the mitotic ventricular zone. Lhx9 protein was tested for interaction with the recently discovered cofactors of LIM-homeodomain proteins and was found to interact strongly both with CLIM1 and CLIM2. The expression pattern and structural characteristics of Lhx9 suggest that it encodes a transcription factor that might be involved in the control of cell differentiation of several neural cell types. Furthermore, Lhx9 protein could act in a combinatorial manner with other LIM-homeodomain factors expressed in overlapping pattern.

Translational profiling of hypocretin neurons identifies candidate molecules for sleep regulation

“…Also ISH and TRAP may differ because of differences between transcription and translation, and occasionally ISH from the Allen Brain Atlas are simply inaccurate. For example, Lhx9 shows strong ubiquitous brain expression in the Allen Brain Atlas at most ages, in contrast to other reports (Bertuzzi et al 1999;Retaux et al 1999;Nakagawa and O'Leary 2001;Gray et al 2004). Nonetheless, even using only the 188 transcripts derived from our most number of transcripts to score, but of their scorable ISH patterns, they showed nearly the same pattern of enrichment as the TRAP data (57% with scores of 1-3).…”

Dynamic spatiotemporal expression of LIM genes and cofactors in the embryonic and postnatal cerebral cortex

“…Of the set of 17 LIM genes comprising Lhx1-9, Lmx1a, 1b, Isl1, 2, and Lmo1-4, we focused on only those genes for which our preliminary studies or published reports from other groups showed expression in the dorsal telencephalon (Boehm et al, 1991;Foroni et al, 1992;Fujii et al, 1994;Porter et al, 1997;Sheng et al, 1997;Kenny et al, 1998;Bertuzzi et al, 1999;Retaux et al, 1999;Millonig et al, 2000). Lhx3,4,6,7,8,Lmx1b, and Isl1, 2 were excluded because previously reported expression patterns reveal their expression to be in only ventral but not dorsal telencephalon, or restricted to nontelencephalic CNS regions, in addition to non-CNS structures (Thor et al, 1991;Li et al, 1994;Tsuchida et al, 1994;Zhadanov et al, 1995;Yamashita et al, 1997;Chen et al, 1998;Grigoriou et al, 1998;Kitanaka et al, 1998).…”

KIF14 is a candidate oncogene in the 1q minimal region of genomic gain in multiple cancers

“…LOC400800 was not expressed at all, suggesting that this putative gene of unknown function (Ota et al, 2004) does not play a role in these tissues. Similarly, it is not surprising that LHX9, a transcription factor involved in nervous system and urogenital development (Bertuzzi et al, 1999;Retaux et al, 1999), is not found in breast tissue or cell lines (Figure 4a), nor is it unusual that PTPRC (CD45), a leukocyte marker (Trowbridge et al, 1991), is not expressed in breast cancer cell lines. The expression of PTPRC in retinoblastoma, HR (Figure 3b), and normal breast (Figure 4a) may be attributable to infiltration of immune cells into these tissues.…”