Chemistry: natural resins or derivatives; peptides or proteins; – Proteins – i.e. – more than 100 amino acid residues – Blood proteins or globulins – e.g. – proteoglycans – platelet...
Reexamination Certificate
1998-04-14
2002-11-26
Eyler, Yvonne (Department: 1647)
Chemistry: natural resins or derivatives; peptides or proteins;
Proteins, i.e., more than 100 amino acid residues
Blood proteins or globulins, e.g., proteoglycans, platelet...
C530S395000, C530S397000, C530S398000, C530S388220, C435S069700, C435S069400
Reexamination Certificate
active
06486303
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for preparing heterodimeric analogs of cysteine knot proteins. More specifically, the invention relates to a method for forming a subunit combination of a cysteine knot protein having an &agr;-subunit and a &bgr;-subunit to prepare a heterodimeric protein analog which comprises the steps of (a) attaching a dimerization domain to the amino termini of both an &agr;-subunit and a &bgr;-subunit of a cysteine knot protein; and (b) dimerizing the &agr;-subunit and &bgr;-subunit to form a heterodimeric protein analog. In another embodiment, the invention relates to a method for forming a subunit combination of a cysteine knot protein having an &agr;-subunit and a &bgr;-subunit to prepare a heterodimeric protein analog which comprises the steps of (a) attaching a dimerization domain to the amino terminus of an &agr;-subunit and the carboxy terminus of a &bgr;-subunit of a cysteine knot protein; and (b) dimerizing the &agr;-subunit and &bgr;-subunit to form a heterodimeric protein analog.
2. Description of the Background
The disclosures referred to herein to illustrate the background of the invention and to provide additional detail with respect to its practice are incorporated herein by reference and, for convenience, are numerically referenced in the following text and respectively grouped in the appended bibliography.
The Glycoprotein Hormones and Their Biological Actions
The glycoprotein hormone family (1-3) consists of three &agr;, &bgr; heterodimeric glycoproteins found in the anterior pituitary gland where they are made and includes luteinizing hormone (LH), follicle stimulating hormone (FSH), and thyroid stimulating hormone (TSH). These hormones are found in most, if not all vertebrates. In some species, a glycoprotein hormone structurally similar to LH is found in the placenta wherein it is synthesized. The human placental hormone is known as human chorionic gonadotropin (hCG). In primates, significant quantities of all the hormones are also found as excretion products in urine. Urine from pregnant women serves as a convenient source of hCG. After menopause, when the secretion of LH and FSH from the anterior pituitary is greatly increased, significant quantities of LH and FSH are found in the urine and are termed human menopausal gonadotropins (hMG). Urine from menopausal women serves as an important source of LH and FSH activities. Urinary hormones (hCG, hMG, hFSH) and recombinant hormones have important clinical and commercial uses.
Gonadotropins such as CG, LH, and FSH play a major role in the reproductive process (4) while the structurally related hormone, TSH, is important for thyroid function. In women, FSH plays a crucial role in the development of follicles that can be ovulated, primarily through its influence on granulosa cells. LH synergizes with FSH and is normally essential for processes of ovulation, luteinization, and luteal function. Nonetheless, high LH levels can reduce fertility and are thought partly responsible for the loss of fertility associated with polycystic ovarian disease. hCG is important for maintenance of pregnancy and its early neutralization leads to infertility. In males LH is required for puberty and, in its absence, there is a failure to acquire the sexual attributes and fertility of an adult. The biological and clinical activities of these hormones are reviewed extensively in several textbooks including those by Yen and Jaffe (4), Adashi, Rock, and Rosenwaks (5), and DeGroot (6).
Both hCG and LH bind to luteinizing hormone receptors (LHR). In the testis, LHR are found primarily in the Leydig cells. In the ovary, LHR are found primarily in thecal cells, FSH-stimulated granulosa cells, and luteal cells. The major role of LH is to stimulate the formation of steroid hormones including the androgens testosterone and androstenedione (Leydig and thecal cells) and progesterone (FSH-stimulated granulosa, thecal, and luteal cells). LH also causes ovulation of mature follicles. While hCG is normally produced only by the placenta during pregnancy, due to its high affinity for LH receptors, the ease with which it can be purified from urine, and its long biological half-life, hCG has been widely used as a substitute for LH. Important clinical uses for hCG include stimulation of fertility in males and induction of ovulation in females.
FSH binds to FSH receptors (FSHR) located primarily in the Sertoli cells of the testis and the granulosa cells of the ovaries. The primary roles of FSH are to stimulate the conversion of androgens to estrogens, to promote the synthesis of inhibin and activin, to promote the development of Sertoli and granulosa cells, and to stimulate gamete maturation. The effect of FSH on granulosa cells leads to follicular maturation, a process during which the oocyte is prepared for ovulation and in which the granulosa cells acquire the ability to respond to LH. Follicle maturation is essential for the ability of LH to induce ovulation.
The differences in the effects of FSH and LH and the complex endocrine interactions between the two hormones cause them to have synergistic effects. For example, normal estrogen production is due to the effect of LH on androgen formation and the influence of FSH on the conversion of androgens to estradiol. Estrogens can inhibit the secretion of FSH and potentiate the secretion of LH. The ability of androgens to be converted to estrogens in non-ovarian tissues can disrupt this complex feedback interaction between steroidogenesis and the secretion of FSH and LH. For this reason, the ratio of LH/FSH activity as well as the absolute hormone levels in blood are important for reproductive functions such as ovulation of the proper number of oocytes during the menstrual and estrus cycles. Other hormones including activin and inhibin can exert an influence on this process, primarily through their influence on FSH secretion from the pituitary gland and their influence on the ovarian response to FSH.
TSH is produced in the anterior pituitary gland and its major function is to regulate the activity of the thyroid gland, causing it to synthesize and release thyroxin. Circulating levels of TSH and thyroxin are usually regulated by a negative feedback mechanism. Increases in TSH secretion usually lead to increased thyroxin synthesis and secretion by the thyroid. As thyroxin levels increase, the secretion of TSH is decreased. In this way there is a balance between the level of TSH and thyroid hormone. High levels of TSH can also stimulate the thyroid gland to remove iodine from circulation. Clinically, TSH can be used to promote the uptake of radioactive iodine and death of the thyroid cells. This form of thyroidectomy has been used to remove hyperactive thyroid tissues.
Uses of Glycoprotein Hormones and the Desirability of Novel Hormone Analogs
Hormones with FSH and LH activities are routinely used in the treatment of human infertility, a problem experienced by approximately 10-15% of all couples (7,8). A major cause of female infertility is polycystic ovarian disease or syndrome, a condition in which endogenous LH levels often appear to be elevated. In principle, infertility caused by inappropriately high LH activity could be suppressed by administration of an inhibitory hormone analog that competed with LH for binding to LHR. It has been known for many years (9,10) that it is possible to prepare analogs of hCG that act as LH antagonists by removing all or part of the oligosaccharides from the hormone. While it is possible to remove most of the oligosaccharides using endonucleases or exonucleases, in practice, it is not practical to remove all of them without denaturing the hormones. The remaining sugars can serve as substrates for enzymes and other factors that can hasten removal of the proteins from circulation (11-13). One potential means of avoiding this problem is to prepare analogs that have been genetically deglycosylated (i.e., by replacing or deleting amino acids in the signals needed for N-linked glycosylation). Th
Eyler Yvonne
Hamud Fozia
University of Medicine & Dentistry of New Jersey
Wise Michael J.
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