Vol. 168, No. 1, 1990 April 16, 1990

BIOCHEMICAL

AND BIOPHYSICAL RESEARCH COMMUNICATIONS

71-77

Pages

EXPRESSION OF ACTIN AND MYOSIN

CHAIN GENES IN SKELETAL,

HEAVY

CARDIAC AND UTERINE MUSCLES OF YOUNG AND OLD RATS Y.K. Molecular Banaras

Jaiswal

and M.S.

Kanungo*

Biology Laboratory, Department of Zoology Hindu University, Varanaai 221 005, India

Received February 5, 1990 levels SUMMARY - The eteady-state of mRNA and transcription of 01(a-SKA) and adult myosin skeletal actin heavy chain (MHC) genes were cardiac and uterine muscles measured in the skeletal, of young (22-25 week) and old (123-135 week) female rats, The effects of lo+' M 17 Pestradiol/dexamethaaone/Tz on their transcription were also studied, Al-SKA mRNA level is lower in the old skeletal The data show that the but is higher in the old myocardium. muscle and uterus, The adult MHC mRNA level is not different in the three muscles of both the ages, The transcription of a-SKA gene is lower in the skeletal muscle and higher in the uterus of old rats. It is unaltered in the myocardium of old rats. The transcription of adult MHC gene is lower in the oid uterus. The effects of hormones on transcription of both the genes are diffWe show that the expreesion erent in the three muscles. of a-SKA gene is tissue-specific and age-related. The over-expression of cu-SKA gene in the old myocardium is possibly due to derepreeoion of the gene of cardiac myocytea, and continuous caused by hypertrophy hemodynamic preauure overload on the old heart. 0 1990 Academic Press, Inc.

INTRODUCTION - The myoblasts

is characterised

withdrawal

from

the

non-proliferating

number of

new muscle

related.

trophy

(6)

coexpressed

of

during of

which the

are

muscle

by cell

requests

structurally of

all

actin

development

(5)

(7) I

a

(2),

functionally

different

cells

appear

proteins

and

has been postulated

mammalian

form multi-

there

and contractile

(4), It

cells. in

(1)

irreversible to

fusion

Concomitantly,

expression

differentiation

in pairs

* To whom reprint

followed

mRNAa

mononucleated

in

of DNA syntheais,

myotubes,

(3))

Switching

genes occurs

cycle

specific

and myosins

differentiation

by cessation

cell

nucleated

actins

myogenic

terminal

that

and myosin and

hyper-

actins

This

are

results

in

may be addressed. 0006-291X/90$1.50 71

Copyright 0 1990 by Academic Press, Inc. All rights of reproduction in any form reserved.

Vol.

168,

No.

alterations in

the

in

We report

cription

of

uterine

are

levela

leading here

and

hormones and

the

cytoplasm

mRNA levels

BIOCHEMICAL

1, 1990

to

that

o(-SKA

of

their

tissue-specific muscles

of

alterations

adult in

RESEARCH

in

MHC, vitro

(ii)

the

phenotypes in

the

by in

the

iaoforms

of

(i)

rates

modulation

age-related

COMMUNICATIONS

mRNAn and protein

occurring

and the

BIOPHYSICAL

corresponding

alterations and

(iii)

AND

the

cells,

steady-state their

of

steroid

trans-

and thyroid

akeletal-,

cardiac-

rat.

MATERIALS AND METHODS - Female albino rats of Wietar strain were used. Skeletal muscle from the fore and hind limbs, cardiac muscle from the uterine muscle from both the uterine horna from entire myocardium and 22-25 week (young) and 123-135 week old rats were uaed. Tissues (old> each age were pooled for each set of seven rata of from five to waa run in duplicate. All experiments were experiments, and each set repeated twice. Precautiona were taken against RNaae activity. containing the cDNA of the genes The following pBR 322 planmida (clone-91: PAM 91-1360) - the 1.36 kb cDNA ware used: Biochem,

M.S.

(1985 b) Mol.

77

Biol.

Biophys. Rep.

Ras. 10,