Growth characteristics, angiotensin II generation, and microarray-determined gene expression in vascular smooth muscle cells from young spontaneously hypertensive rats.
BACKGROUND
We have demonstrated that vascular smooth muscle cells (VSMCs) derived from spontaneously hypertensive rats (SHR) show exaggerated growth and produce angiotensin (Ang) II and growth factors. These may reflect intrinsic abnormalities in SHR that are not caused by excessive blood pressure, and are associated with genetic abnormalities.


OBJECTIVE
To evaluate whether these characteristics of VSMCs from SHR are associated with hypertension or genetic factors.


METHODS
VSMCs were obtained by an explant method from aortas of 4-week-old male SHR/Izumo and Wistar-Kyoto (WKY)/Izumo rats. We evaluated growth characteristics by [3H]thymidine incorporation and cell number increases, immunofluorescence of alpha-smooth muscle (alpha-SM) actin, mRNA expressions of phenotype markers, Ang II-generating system components, and growth factors by reverse transcription and polymerase chain reaction analysis, and Ang II levels by radioimmunoassay in VSMCs. Expression of 850 genes in VSMCs was evaluated by microarray.


RESULTS
VSMCs from young SHR showed increased basal DNA synthesis and higher responses of DNA synthesis and cell numbers in response to calf serum. Ang II was significantly increased in conditioned medium and cell extracts from SHR-derived VSMCs than in those from WKY rat-derived VSMCs. mRNA expression of Ang II-generating proteinases, such as cathepsin D and angiotensin-converting enzyme, was greater in VSMCs from SHRs than in cells from WKY rats. Expression of transforming growth factor-beta1, platelet-derived growth factor A-chain and basic fibroblast growth factor mRNAs was greater in VSMCs from SHRs than in cells from WKY rats. Expression of mRNAs of phenotype markers, such as matrix gamma-carboxyglutamic acid (Gla) and osteopontin, was also greater in VSMCs from SHR than in cells from WYK rats. Microarray study showed that VSMCs derived from young SHR increasingly express genes for many enzymes, adhesion molecules and cytokines.


CONCLUSIONS
This study determined that VSMCs derived from young SHR show exaggerated growth, produce Ang II and increasingly express several enzymes, adhesion molecules and cytokines, which are independent of hypertension and possibly associated with genetic abnormalities.
Hu
Wen-Yang
WY
Second Department of Internal Medicine, Nihon University School of Medicine, Tokyo, Japan.
Fukuda
Noboru
N
Kanmatsuse
Katsuo
K
D000367:Age Factors; D000804:Angiotensin II / Q000096:biosynthesis* / Q000235:genetics*; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D004195:Disease Models, Animal; D020869:Gene Expression Profiling / Q000379:methods*; D005819:Genetic Markers / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000235:genetics; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics; D008297:Male; D008955:Models, Cardiovascular; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011918:Rats, Inbred SHR / Q000235:genetics* / Q000254:growth & development*; D011921:Rats, Inbred WKY; D013599:Systole / Q000502:physiology; D014158:Transcription, Genetic / Q000235:genetics
D005819:Genetic Markers; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D000804:Angiotensin II