The interface of sigma with core RNA polymerase is extensive, conserved, and functionally specializedThe sigma subunit of eubacterial RNA polymerase is required throughout initiation, but how it communicates with core polymerase (alpha(2)betabeta') is poorly understood. The present work addresses the location and function of the interface of sigma with core. Our studies suggest that this interface is extensive as mutations in six conserved regions of sigma(70) hinder the ability of sigma to bind core. Direct binding of one of these regions to core can be demonstrated using a peptide-based approach. The same regions, and even equivalent residues, in sigma(32) and sigma(70) alter core interaction, suggesting that sigma(70) family members use homologous residues, at least in part, to interact with core. Finally, the regions of sigma that we identify perform specialized functions, suggesting that different portions of the interface perform discrete roles during transcription initiation.
Antiangiogenic Agents Are Effective Inhibitors of EndometriosisM. Louise Hull, D. Stephen Charnock‐Jones, Clement L. K. Chan et al.|The Journal of Clinical Endocrinology & Metabolism|2003 Endometriosis is a disease in which the lining of the uterus (endometrium), shed at the time of menstruation, becomes established at sites such as the peritoneum and ovaries. These explants develop a rich blood supply that enables them to survive and grow. We hypothesized that inhibitors of angiogenesis would prevent this growth by disrupting sensitive vessels supplying endometriotic lesions. Vessels sensitive to angiogenic antagonism have few associations with pericyte cells. The vessels supplying human endometriotic lesions were immunohistochemically characterized and found to be predominantly pericyte free. A model in which human endometrium is implanted into nude mice was used to test the effects of two antagonists of the angiogenic growth factor, vascular endothelial cell growth factor A. Soluble truncated receptor (flt-1; P = 0.002) and an affinity-purified antibody to human vascular endothelial cell growth factor A (P = 0.03) significantly inhibited the growth of nude mouse explants. Pericyte-free vessels were shown to supply endometrial lesions in nude mice and were disrupted in lesions taken from soluble flt-1-treated mice. In summary, antiangiogenic agents inhibited the growth of explants in an in vivo model of endometriosis by disrupting the vascular supply, and this effect is likely to apply to the human disease. These findings suggest that antiangiogenic agents may provide a novel therapeutic approach for the treatment of endometriosis.
The Role of microRNAs in Ovarian Granulosa Cells in Health and DiseaseJiajie Tu, Hoi‐Hung Cheung, Clement L. K. Chan et al.|Frontiers in Endocrinology|2019 The granulosa cell (GC) is a critical somatic component of the ovary. It is essential for follicle development by supporting the developing oocyte, proliferating and producing sex steroids and disparate growth factors. Knowledge of the GC's function in normal ovarian development and function, and reproductive disorders, such as polycystic ovary syndrome (PCOS) and premature ovarian failure (POF), is largely acquired through clinical studies and preclinical animal models. Recently, microRNAs have been recognized to play important regulatory roles in GC pathophysiology. Here, we examine the recent findings on the role of miRNAs in the GC, including four related signaling pathways (Transforming growth factor-β pathway, Follicle-stimulating hormones pathway, hormone-related miRNAs, Apoptosis-related pathways) and relevant diseases. Therefore, miRNAs appear to be important regulators of GC function in both physiological and pathological conditions. We suggest that targeting specific microRNAs is a potential therapeutic option for treating ovary-related diseases, such as PCOS, POF, and GCT.
A new molecular variant of luteinizing hormone associated with female infertilityWu-xiang Liao, A.C. Roy, Clement L. K. Chan et al.|Fertility and Sterility|1998 Pelvic Adhesiolysis—The Assessment of Symptom Relief by 100 PatientsClement L. K. Chan, C. Wood|Australian and New Zealand Journal of Obstetrics and Gynaecology|1985 This study reports the effectiveness of pelvic adhesiolysis in relieving symptoms in patients with gross pelvic adhesions. Based on 100 patients' responses to a questionnaire, adhesiolysis was found to be of value in treating infertility, chronic pelvic pain and dyspareunia. Its value in relieving dysmenorrhoea was less certain while it did not influence menstrual pattern or premenstrual tension.