TY - JOUR
T1 - Distribution and activation of protein kinase C in the rat testis tissue
AU - Nikula, Hannu
AU - Naor, Zvi
AU - Parvinen, Martti
AU - Huhtaniemi, Ilpo
N1 - Funding Information:
These studies were supported by grants from the Academy of Finland (M.P., I.H.), the University of Helsinki (I.H.), the Finnish Cultural Fund (I.H.), NIH grant HD-16279 (Z.N.), and by the United States-Israel Binational Science Foundation We thank Dr. I. SeppHla for advice with HPLC and Dr. J. Hermon in setting up the enzyme assay. The skilful technical assistanceo f Ms. Marjatta Vallas is gratefully acknowledged.
PY - 1987/1
Y1 - 1987/1
N2 - The distribution and role of the calcium-activated, phospholipid-dependent protein kinase C (PK-C) was studied in rat testis. When testis tissue was homogenized in the presence of 2 mmol/1 EDTA and EGTA, the majority (> 70%) of the PK-C activity was soluble, the rest was released from the particulate fraction by solubilization with 0.3% Triton X-100. Without chelating agents the soluble PK-C activity was undetectable, and only partially recovered from solubilized membranes. Preincubation of the tissue with the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA, 10-7 mol/1) translocated PK-C to the membranes, and the majority of this activity was recovered by solubilization. Mobility of testicular soluble PK-C activity in HPLC-DEAE cellulose chromatography was similar to that of the brain enzyme. This single step purified testicular PK-C activity 140-fold. The specific activity and subcellular distribution of PK-C was similar in whole testis tissue and separated seminiferous tubules (160-210 pmol 32P-mg protein-1 · min-1 in the soluble and particulate fractions), but 2- to 3-fold higher in purified Leydig cells. However, the majority of total testicular PK-C activity appeared to be of tubular origin. Unilateral cryptorchidism for 1 week reduced PK-C of the abdominal testis by 50%, and the activity of dissected seminiferous tubules varied according to the epithelial wave. Both findings suggest that the bulk of the activity resides in the seminiferous epithelium. Involvement of PK-C in Leydig cell function was demonstrated using the TPA, which at 10-7 mol/1 inhibited basal cAMP production by 50% (P < 0.01) but increased that of testosterone by 2- to 3-fold (P < 0.01). On the other hand, when incubated with hCG, TPA inhibited both cAMP and testosterone production; the ED50s of hCG stimulation increased 4-to 10-fold with both parameters. It is concluded that PK-C activity is present in both the seminiferous tubules and Leydig cells, and is involved in the regulation of these testicular compartments. Its total activity and subcellular distribution are at variance according to the functional state and endocrine milieu of the testis.
AB - The distribution and role of the calcium-activated, phospholipid-dependent protein kinase C (PK-C) was studied in rat testis. When testis tissue was homogenized in the presence of 2 mmol/1 EDTA and EGTA, the majority (> 70%) of the PK-C activity was soluble, the rest was released from the particulate fraction by solubilization with 0.3% Triton X-100. Without chelating agents the soluble PK-C activity was undetectable, and only partially recovered from solubilized membranes. Preincubation of the tissue with the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA, 10-7 mol/1) translocated PK-C to the membranes, and the majority of this activity was recovered by solubilization. Mobility of testicular soluble PK-C activity in HPLC-DEAE cellulose chromatography was similar to that of the brain enzyme. This single step purified testicular PK-C activity 140-fold. The specific activity and subcellular distribution of PK-C was similar in whole testis tissue and separated seminiferous tubules (160-210 pmol 32P-mg protein-1 · min-1 in the soluble and particulate fractions), but 2- to 3-fold higher in purified Leydig cells. However, the majority of total testicular PK-C activity appeared to be of tubular origin. Unilateral cryptorchidism for 1 week reduced PK-C of the abdominal testis by 50%, and the activity of dissected seminiferous tubules varied according to the epithelial wave. Both findings suggest that the bulk of the activity resides in the seminiferous epithelium. Involvement of PK-C in Leydig cell function was demonstrated using the TPA, which at 10-7 mol/1 inhibited basal cAMP production by 50% (P < 0.01) but increased that of testosterone by 2- to 3-fold (P < 0.01). On the other hand, when incubated with hCG, TPA inhibited both cAMP and testosterone production; the ED50s of hCG stimulation increased 4-to 10-fold with both parameters. It is concluded that PK-C activity is present in both the seminiferous tubules and Leydig cells, and is involved in the regulation of these testicular compartments. Its total activity and subcellular distribution are at variance according to the functional state and endocrine milieu of the testis.
KW - Cryptorchidism
KW - Cyclic AMP
KW - Leydig cell
KW - Phorbol ester
KW - Protein kinase C
KW - Seminiferous tubule
KW - Steroidogenesis
KW - Testosterone
UR - http://www.scopus.com/inward/record.url?scp=0023270367&partnerID=8YFLogxK
U2 - 10.1016/0303-7207(87)90062-1
DO - 10.1016/0303-7207(87)90062-1
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AN - SCOPUS:0023270367
SN - 0303-7207
VL - 49
SP - 39
EP - 49
JO - Molecular and Cellular Endocrinology
JF - Molecular and Cellular Endocrinology
IS - 1
ER -