Tadashi Kaname

Mutation of the mouse klotho gene leads to a syndrome resembling ageing.

A new gene, termed klotho, has been identified that is involved in the suppression of several ageing phenotypes. A defect in klotho gene expression in the mouse results in a syndrome that resembles human ageing, including a short lifespan, infertility, arteriosclerosis, skin atrophy, osteoporosis and emphysema. The gene encodes a membrane protein that shares sequence similarity with the β-glucosidase enzymes. The klotho gene product may function as part of a signalling pathway that regulates ageing in vivo and morbidity in age-related diseases.

Disruption of the midkine gene (Mdk) resulted in altered expression of a calcium binding protein in the hippocampus of infant mice and their abnormal behaviour

Midkine (MK) is a growth factor implicated in the development and repair of various tissues, especially neural tissues. However, its in vivo function has not been clarified.

Midkine expression in human breast cancers : Expression of truncated form

The expression of midkine (MK), a growth/differentiation factor,was assessed in 34 surgically resected specimens ofprimary breast cancer or mastopathy. Using reverse transcriptase-polymerasechain reaction (RT-PCR) analysis, all of the non-cancerousand cancerous tissues were found to express MKexcept for one breast cancer specimen. Northern blotanalysis revealed that MK mRNA was also expressedin the normal breast tissues examined. Immunohistochemical analysisof the MK protein was performed on alimited number of the specimens, showing that somecancerous tissues were immunoreactive with anti-MK antibodies. Furthermore,using RT-PCR analysis, expression of not only thewild-type but also a truncated form of MK,which was recently found in various human tumorcell lines, was detected in 6 of 26cancerous tissues but not in non-cancerous tissues.

Expression of truncated midkine in human colorectal cancers.

Midkine (MK) is a growth differentiation factor originally found as the product of a retinoic acid-responsive gene. The expression of MK was examined in 35 surgically resected specimens of primary colorectal cancer using the reverse transcription-polymerase chain reaction (RT-PCR). All of the cancerous tissues expressed MK. In 5/25 cancerous tissues a truncated form of MK, which was recently found in various human tumor cell lines, was detected in addition to the full-size MK. In contrast, the truncated from of MK could not be detected in non-cancerous tissues, whereas the wild-type form was detected in 8/10 non-cancerous tissues. These results suggest that the expression of the truncated form of MK may be associated with tumorigenesis.

Comparison of ES cell fate in sandwiched aggregates and co-cultured aggregates during blastocyst formation by monitored GFP expression

Markers and the means to detect them are required to monitor the fate of living cells. However, few suitable markers for living cells were known until a green fluorescent protein (GFP) was discovered. We have established mouse embryonic stem (ES) cell lines that express mutant GFP under the chicken β‐actin (CAG) promoter. Using these cell lines, we were able to follow the migration of ES cells during blastocyst formation both in sandwiching and coculture methods, even if only a single ES cell was used. Furthermore, the contribution of ES cells to the inner cell mass (ICM) was easily estimated at the blastocyst stage. We compared sandwiching with coculture aggregation relative to the contribution of the ES cell in the ICM, and the results indicated that there was no difference in the ratios of chimeric embryos having ICM contributed from cultured ES cells. Furthermore, an aggregated single ES cell was able to contribute three or four cells to the ICM at the blastocyst stage. Thus we conclude that one, instead of two, embryos is enough to make aggregation with ES cells, and a single ES cell attached to an embryo is enough to produce germline chimeras. Moreover, we could clearly observe single cell fate during blastocyst formation. This suggests that our established cell line can be used for monitoring single cell fate in vivo. In addition, we have shown that up to five doses of 30 sec of UV irradiation using GFP filters have no effect on the embryonic development. Mol. Reprod. Dev. 52:376–382, 1999.

Naso-maxillary deformity due to frontonasal expression of human transthyretin gene in transgenic mice.

Background Retinoic acid, a metabolic product of retinol, is essential for craniofacial morphogenesis. Transthyretin (TTR) is a plasma protein delivering retinol to tissues. We produced several transgenic mouse lines using the human mutant TTR (hTTRMet30) gene to establish a mouse model of familial amyloidotic polyneuropathy. One of the lines showed an autosomal dominant inheritance of naso‐maxillary deformity termed Nax.