Induction of various androgen-dependent esteroproteases (trypsin-like and chymotrypsin-like enzymes) by tri-iodo-L-thyronine in the submandibular glands of female mice and mice with testicular feminization

Thyroid hormone (3,5,3'-triido-L-thyronine) masking/inversion of stimulatory effect of androgen on expression of mk1, a true tissue kallikrein, in the mouse submandibular gland

We studied hormonal regulation of the expression of mkl, a true tissue kallikrein, in the submandibular gland (SMG) of ICR, C3H/ HeN, and F1 (mice from male C3H/HeN x female ICR and in the ones from male ICR x female C3H/HeN). In these mouse strains, mk1 was low in content in males, abundant in females, and increased remarkably by castration of males. In the case of ICR and both F1 mice, injection of 5alpha-dihydrotestosterone (DHT) reduced the mkl level of castrated and female mice. However, the mkl content in female C3H/ HeN mice (or castrated C3H/HeN) was further increased by DHT. To investigate the real action of DHT on mk1 expression, we examined the effects of adrenoectomy/glucocorticoid (dexamethasone, Dex) administration; DHT administration into castrated and adrenoectomized mice; ovariectomy/female hormone (17beta-estradiol, progesterone) administration; and hypophysectomy/combinatory administration of DHT, Dex, and thyroid hormone (3,5,3'-triiodo-L-thyronine, T3) on the mk1 expression in the SMG of ICR mice. Adrenoectomy or ovariectomy did not change the characteristic pattern of mk1 expression in male and female ICR mice. In hypophysectomized (Hypox) ICR male mice, the mk1 content was increased to the same level as in normal ICR females, and DHT administration into the Hypox mice further increased the mk1 level. However, combinatory administration of DHT + T3 or of DHT + T3 + Dex into the Hypox mice lowered the mkl content to the level of normal ICR males, whereas T3 single administration had no effect. Dex single administration into the Hypox mice increased the mkl level to an even higher than that observed with DHT administration. The mk1 level in Hypox mice was not significantly changed by coadministration of Dex with T3. From these results, we conclude that 1) mk1 expression is fundamentally stimulated by androgen (DHT) as are other mk isozymes, such as mk9, mk13, mk22, and mk26 in the mouse SMG, 2) the effect (stimulatory) of DHT on mk1 expression becomes, however, inverted (inhibitory) in the presence of T3. Although the serum T3 level of C3H/HeN female (0.52 ng/ml) was not significantly different from that of C3H/HeN males or ICR mice, coadministration of T3 into C3H/HeN females with a fixed amount of DHT (20 mg/kg body weight) dose dependently repressed the DHT-induced increase in mkl expression, suggesting the lower sensitivity of C3H/HeN females to T3.

Effects of pretreatment with androgen or thyroid hormone on androgen-induced proliferation of granular convoluted tubular cells in mouse submandibular glands

The effects of pretreatment with androgen or thyroid hormone on androgen-induced proliferation of granular convoluted tubular cells (GCT cells) in the submandibular glands of ovariectomized female BALB/c or C57BL/6 mice were investigated. The proliferation of GCT cells was estimated by their labeling index. Daily injections of 5 alpha-dihydrotestosterone (DHT) (100 micrograms/mouse/day) caused a transient increase in the labeling index of GCT cells of ovariectomized 60-day-old BALB/c mice during the first four injections, but injections of thyroxine (T4) (15 micrograms/mouse/day) did not. On the other hand, both DHT and T4 increased the esteroprotease activity, a marker of the differentiation of GCT cells, time dependently. Injections of DHT into ovariectomized 102-day-old BALB/c mice also caused a transient increase in the labeling index of GCT cells. However, pretreatment of ovariectomized 60-day-old BALB/c mice with DHT for 4 or 14 days completely abolished the DHT-induced increase in the labeling index of 102-day-old mice, and pretreatment with T4 for 14 days reduced this increase. Pretreatment with DHT or T4 for 14 days did not affect the DHT-induced increase in esteroprotease activity. Pretreatment of ovariectomized 60-day-old C57BL/6 mice with DHT for 14 days also completely abolished the DHT-induced increase in the labeling index of GCT cells at the age of 102 days, but pretreatment with T4 for 14 days did not affect the increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Basic isozymes of chymotrypsin-like esteroprotease from the mouse submandibular gland

Basic isozymes of chymotrypsin-like esteroprotease from mouse submandibular glands were purified 60-80-fold by a rather simple procedure consisting of CM-Sepharose CL6B chromatography and gel filtration on Sephadex G-100. The purified sample contained three major isozymes (A, B, C) and some minor ones. Their isoelectric points were between pH 10 and 11. The molecular weights of the main isozymes were estimated at 28000 by SDS-polyacrylamide gel electrophoresis. The acidic isozyme (A) separated into two polypeptide chains whose molecular weights were 21500 and 6500. Specific activities of these isozymes using Bz-Tyr-OEt as substrate were comparable to that of bovine pancreatic alpha-chymotrypsin, but they hydrolyzed casein 10 times slower than did alpha-chymotrypsin. The hydrolytic activities of these isozymes on Bz-Tyr-OEt were inhibited by diisopropylfluorophosphate, tosyl-L-phenylalanine chloromethyl ketone and chymostatin, but they were 400 times less sensitive to chymostatin than was alpha-chymotrypsin.

Hormonal regulation of chymotrypsin-like esteroproteases in the mouse submandibular gland

The activities of chymotrypsin-like esteroproteases in the mouse submandibular gland were additively induced by 5 alpha-dihydrotestosterone (DHT) and triiodothyronine (T3). Zymograms showed that there are many isozymes whose activities are regulated by DHT and/or T3. Some isozymes seemed to be hormone-independent. Histochemical studies revealed that all these isozymes are localized in the granular convoluted tubules.