Hiroshi KAGOSHIMA et al. (2007) International Worm Meeting "Systematic analysis of AFD-specific enhancers in C. elegans."

Hiroshi KAGOSHIMA, Yuji KOHARA, Junko Kajiwara

[International Worm Meeting, 2007]

How can transcription factors control gene expression? To investigate the mechanism of the cell-specific transcriptional regulation, we first chose AFD thermosensory neuron as our target cell. Systematic deletion analysis of 11 AFD promoters revealed the following: (i) the shortest 50 bp fragment (gcy-8) was enough to drive AFD-specific expression; (ii) AFD expression was not regulated by a single mechanism; (iii) silencer elements would play important roles to define neuronal specific expression; (iv) some promoters required multiple and separately located elements. Furthermore, we found that several promoters, including gcy-8 promoter, lost AFD expression under the double mutant background of ttx-1 and ceh-14, both of which encode homeobox transcription factors expressed in AFD. Gel shift assay using purified TTX-1 and CEH-14 proteins indicated that these proteins could directly bind to the 50 bp fragment of gcy-8 promoter. Finally, forced expression of both ttx-1 and ceh-14 genes in AWB chemosensory neuron could induce ectopic gcy-8::GFP expression in AWB in addition to the endogenous expression in AFD. These results suggest that ttx-1 and ceh-14 genes play pivotal roles in AFD specific expression. Further analysis will be reported at the meeting.

Ichiro Kawasaki et al. (2002) Japanese Worm Meeting "Systematic RNAi Analysis of Genes Expressed in Primordial Germ Cells, Z2 and Z3"

Ichiro Kawasaki, Yuji KOHARA, Junko Kajiwara

[Japanese Worm Meeting, 2002]

Hiroshi Kagoshima et al. (2005) International Worm Meeting "BRO-1, an interaction partner of RNT-1."

Yuji KOHARA, Hiroshi KAGOSHIMA, Junko Kajiwara, Shohei MItani

[International Worm Meeting, 2005]

The RUNX genes are known to play pivotal roles in development of various animals from worm to human. In vertebrate, there are three RUNX genes, RUNX1, 2 and 3, which are critical transcription factors for development of blood, bone and gastric epithelia, respectively. The RUNX proteins share a region of high homology, termed the Runt domain, which is responsible for specific DNA binding and heterodimerization with its partner subunit, Brother. Although Brother itself cannot bind to DNA, it binds to RUNX proteins and enhances their DNA binding activity. Human RUNX1 was previously known as AML1 (Acute Myeloid Leukemia 1), which is the most frequent target of chromosomal translocations associated with leukemia. Interestingly, Human Brother is also shown to associated with the recurrent chromosome rearrangement associated with acute myelogenous leukemia. The genome project revealed that C. elegans bears a RUNX homolog, rnt-1, and a Brother homolog, bro-1. Recently, we have shown that rnt-1 is allelic to mab-2 and its function is required for the asymmetrical T cell division in hermaphrodite and development of the ray neurons in male (manuscript in preparation).nbsp;nbsp;We started to study the function of bro-1 in C. elegans. BRO-1::GFP was expressed in the H1, H2, V1-6, T and Q blast cells at the comma stage, and in the seam cells from larval to adult stages. This expression pattern was very similar to that of RNT-1::GFP. We next isolated several knockout strains of bro-1. The bro-1 mutants exhibited a loss of the asymmetry of the T cell division in hermaphrodite and abnormal ray morphology in the male tail, which are almost identical to the rnt-1 mutant phenotypes. These results strongly suggest that BRO-1 and RNT-1 would function as a single cooperative unit in C. elegans. Moreover, it is also reported that the RUNX/Brother heterodimer has more interacting partners (i.e., AP-1, p53, Groucho/TLE, p300/CBP) and it might serve as a core to form larger transcriptional complex, enhanceosome. For futher understanding of the RUNX/Brother complex function, it is necessary to identify their interacting partners. We are going to investigate RNT-1/BRO-1-binding proteins by co-immunoprecipitation. Further results will be discussed at the meeting.

Hiroshi KAGOSHIMA et al. (2007) International Worm Meeting "Molecular Analysis of the Antarctic Nematodes."

Takanori Narita, Junko Kajiwara, Yuji KOHARA, Tadasu SHIN-I, Hiroshi KAGOSHIMA

[International Worm Meeting, 2007]

Antarctica is an extreme environment for life. There, biological activity is severely restricted not only by low temperature but also by lack of water supply. It may seem curious that the continent is covered with a tremendous amount of ice, however organisms can utilize only liquid water (frozen water is useless for life). The cold climate also results in limited rainfall and low humidity in the air. Nematodes are one of the representative animals that can live in Antarctica. The aim of our project is to understand nematodes strategy to survive and even propagate their habitat in such a harsh environment. To elucidate the special features of the Antarctic nematodes, we are going to analyze their cDNA and genome sequences, and compare them with those of the other nematoda species, including C. elegans. Through this study, we would like to figure out the molecular mechanisms to adapt to the extreme environment, e.g. resistance to freezing and dehydration. Currently, we are preparing an Antarctic worm catalog, using both molecular data (18S and 28S rDNA sequence) and morphological data, collaborating with Dr. P. Convey (British Antarctic Survey). This approach will help to address the problems in classical morphological taxonomy, and provide a basis of comparative biology of the Antarctic nematodes. In parallel, we are constructing cDNA libraries of Panagrolaimus davidi, which has high-level resistance to freezing and dehydration. Non-C. elegans scientists are welcome to our poster for discussion, especially who are interested in life at the limits! (Of course, C. elegans scientists are welcome, too!!).

Hiroshi Kagoshima et al. (2004) East Asia Worm Meeting "RNT-1/MAB-2, a key regulator of asymmetric cell division of the T cell"

Yuji KOHARA, Hitoshi Sawa, Katsuya SHIGESADA, Shohei MItani, Junko Kajiwara, Hiroshi KAGOSHIMA, Thomas R Burglin

[East Asia Worm Meeting, 2004]

rnt-1 encodes a transcription factor belongs to the RUNX gene family, which play critical roles in development of various animals from fly to human. C. elegans runt, is originally identified as a secondary pair-rule gene, which regulates segmentation of the embryo. Human RUNX1, is previously known as AML1 (Acute Myeloid Leukemia 1), which is essential for hematopoiesis. RUNX2 and RUNX3 control development of skeletal system and gastric epitherial tissue, respectively. In C. elegans , RNT-1::GFP is expressed in H0-2, V1-6, and T cells at comma stage, mainly in seam cells from larval to adult stages. We have isolated several mutant alleles of the rnt-1 gene, and all of them showed defects in asymmetric cell division of the T cell and abnormal morphology of the ray neurons in the male tail. Complementation analysis showed that rnt-1 is identical to mab-2. Lineage analysis of rnt-1 animals revealed that the T cell lost its polarity and underwent symmetric cell division (both T.a and T.p took T.a-like hypodermis cell fate). Wnt signaling (i.e. lin-44 , lin-17 , lin-17 ) controls the asymmetric division of the T cell, suggesting that rnt-1 participate in this signal pathway. It is remarkable that the Wnt signaling regulates differentiation of human immune T cell, and RUNX1 is necessary for the signal transduction by cooperating with LEF-1/TCF1, human homolog of lin-17 . Moreover, there is interesting similarity between that the vertebrate RUNX genes are required for the tissues containing stem cells (blood: RUNX1, bone: RUNX2, gastric epitheria: RUNX3), and that C. elgans rnt-1 is also required for the H, V and T blast (stem) cells. We thus hypothesized that general role of the RUNX genes is a regulator between proliferation and differentiation of stem cells via Wnt signal pathway. Further discussion based on more results will be made at the meeting.