Overlapping and non-overlapping roles of the class-I histone deacetylase-1 corepressors LET-418, SIN-3, and SPR-1 in Caenorhabditis elegans embryonic development

BACKGROUND

Histone deacetylase (HDAC)-1, a Class-I HDAC family member, forms three types of complexes, the nucleosome remodeling deacetylase, Sin3, and CoREST complexes with the specific corepressor components chromodomain-helicase-DNA-binding protein 3 (Mi2/CHD-3), Sin3, and REST corepressor 1 (RCOR1), respectively, in humans.

OBJECTIVE

To elucidate the functional relationships among the three transcriptional corepressors during embryogenesis.

METHODS

The activities of HDA-1, LET-418, SIN-3, and SPR-1, the homologs of HDAC-1, Mi2, Sin3, and RCOR1 in Caenorhabditis elegans during embryogenesis were investigated through measurement of relative mRNA expression levels and embryonic lethality given either gene knockdown or deletion. Additionally, the terminal phenotypes of each knockdown and mutant embryo were observed using a differential-interference contrast microscope. Finally, the functional relationships among the three corepressors were examined through genetic interactions and transcriptome analyses.

RESULTS

Here, we report that each of the corepressors LET-418, SIN-3, and SPR-1 are expressed and have essential roles in C. elegans embryonic development. Our terminal phenotype observations of single mutants further implied that LET-418, SIN-3, and SPR-1 play similar roles in promoting advancement to the middle and late embryonic stages. Combined analysis of genetic interactions and gene ontology of these corepressors indicate a prominent overlapping role among SIN-3, SPR-1, and LET-418 and between SIN-3 and SPR-1.

CONCLUSION

Our findings suggest that the class-I HDAC-1 corepressors LET-418, SIN-3, and SPR-1 may cooperatively regulate the expression levels of some genes during C. elegans embryogenesis or may have some similar roles but functioning independently within a specific cell.

Hepatic cirrhosis: magnetisation transfer contrast in the globus pallidus

The magnetisation transfer ratio (MTR), a quantitative tissue characteristic, and the pallidal index were measured in the globus pallidus of 37 patients with hepatic cirrhosis and 37 control subjects. The MTR decreased with severity of the disease, as indicated by the serum total bililubin, indocyanine green 15-min retention rate, and plasma ammonia. The pallidal index correlated significantly with haematological parameters, although the correlation coefficients tended to be lower than those between MTR and haematological parameters. This change in MTR corresponded to the results of the manganese chloride experiments. T1 shortening in the pallidum of patients with cirrhosis is presumably caused by paramagnetic effects, and possibly attributed to manganese deposition.

[A case of bacteremia due to Salmonella enteritidis in healthy man]

Although bacteremia caused by non-typhoidal salmonella is frequently observed in immunocompromised hosts, it is rare to find this condition in healthy subjects. In this report, we present a case of bacteremia due to Salmonella enteritidis detected in a healthy man. A 59-year-old man was admitted to our hospital with a fifty-day history of fever on May 18, 1985. On admission, he showed no symptoms except high body temperature (38.8 degrees C). In the laboratory data, C-reactive protein was 3+, white- cell count was 9600, and erythrocyte sedimentation rate was 12 mm/h. Culture in blood and stool yielded Salmonella enteritidis. However, no abnormal findings were found in UGIS, barium enema, OC + DIC, abdominal CT and echography. As soon as Ampicillin was administered, the fever was gone and the blood culture yielded nothing. After six months, the stool culture was negative for pathological intestinal bacterial flora and he was in good physical condition. Generally, bacteremia develops mainly in the immunocompromised hosts, such as patients with neoplastic disease, AIDS, leukemia or collagen disease. The literature provides so far twenty three adult cases of bacteremia due to non-typhoidal salmonella in Japan. Only two of them had no systemic disease as well as our case. Although it is unknown why bacteremia developed in this healthy man, we reported that bacteremia developed rarely in subjects with healthy condition.