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  1. Tang MM, Surana U, Leong KF, Pramano ZAD
    Int J Dermatol, 2021 Jul;60(7):e288-e290.
    PMID: 33728648 DOI: 10.1111/ijd.15523
    Matched MeSH terms: Connexins/genetics
  2. Ruszymah BHI, Wahida IF, Zakinah Y, Zahari Z, Norazlinda MD, Saim L, et al.
    Med J Malaysia, 2005 Aug;60(3):269-74.
    PMID: 16379178
    Twenty percent of all childhood deafness is due to mutations in the GJB2 gene (Connexin 26). The aim of our study was to determine the prevalence and spectrum of GJB2 mutations in childhood deafness in Malaysia. We analyzed the GJB2 gene in 51 deaf students from Sekolah Pendidikan Khas Alor Setar, Kedah. Bidirectional sequencing indicates that 25% of our childhood deafness has mutation in their GJB2 gene. Sixty two percent of these children demonstrate V37I missense mutation. Interestingly, V37I mutation in the GJB2 gene have been reported as polymorphism in Western countries, however in our country it behaved as a potentially disease-causing missense mutation, causing childhood deafness as it was not found in the normal control.
    Matched MeSH terms: Connexins/genetics*
  3. Fukunaga I, Shiga T, Chen C, Oe Y, Danzaki K, Ohta S, et al.
    Stem Cell Res, 2020 03;43:101674.
    PMID: 31926383 DOI: 10.1016/j.scr.2019.101674
    The gap junction beta-2 (GJB2) gene is the most common genetic cause of hereditary deafness worldwide. Especially, V37I mutation in GJB2 is most prevalent in Southeast Asia including Thailand, Malaysia, and Indonesia. Furthermore, it is the second most prevalent cause in Japan and China, and exhibits an audiometric phenotype of mild-to-moderate hearing loss. In this study, we generated induced pluripotent stem cells (iPSC) from peripheral blood mononuclear cells (PBMCs) of patient with homozygous V37I mutation. This iPSC line will be a powerful tool for investigating the pathogenesis and for developing a treatment for GJB2-related hearing loss.
    Matched MeSH terms: Connexins/genetics*
  4. Acosta ML, Mat Nor MN, Guo CX, Mugisho OO, Coutinho FP, Rupenthal ID, et al.
    Neural Regen Res, 2021 Mar;16(3):482-488.
    PMID: 32985469 DOI: 10.4103/1673-5374.290097
    Compounds that block the function of connexin and pannexin protein channels have been suggested to be valuable therapeutics for a range of diseases. Some of these compounds are now in clinical trials, but for many of them, the literature is inconclusive about the molecular effect on the tissue, despite evidence of functional recovery. Blocking the different channel types has distinct physiological and pathological implications and this review describes current knowledge of connexin and pannexin protein channels, their function as channels and possible mechanisms of the channel block effect for the latest therapeutic compounds. We summarize the evidence implicating pannexins and connexins in disease, considering their homeostatic versus pathological roles, their contribution to excesive ATP release linked to disease onset and progression.
    Matched MeSH terms: Connexins
  5. Zainal SA, Md Daud MK, Abd Rahman N, Zainuddin Z, Alwi Z
    Int J Pediatr Otorhinolaryngol, 2012 Aug;76(8):1175-9.
    PMID: 22613756 DOI: 10.1016/j.ijporl.2012.04.027
    To identify the mutations in the GJB2 gene and to determine its association with non-syndromic hearing loss in Malays.
    Matched MeSH terms: Connexins/genetics*
  6. Asma A, Ashwaq A, Norzana AG, Atmadini AM, Ruszymah BH, Saim L, et al.
    Med J Malaysia, 2011 Jun;66(2):124-8.
    PMID: 22106692 MyJurnal
    Recently, molecular testing for GJB2 mutations has become the standard of care for the diagnosis of patients with non syndromic hearing impairment of unknown cause. The aims of this study are to determine the association between GJB2 mutation and GJB6 and to report the variation of mutations in deaf students who have heterozygous GJB2. This retrospective study was conducted at Universiti Kebangsaan Malaysia Medical Center (UKMMC). Data was collected from previous files and records from Tissue Engineering and Human Genetic Research Group Laboratory. Approval from Ethical Committee was obtained prior to the study. A total of 138 students have been screened in previous studies in UKMMC for the presence of GJB2 mutations as a cause for hearing loss. Thirty four of the 138 subjects have GJB2 mutations; 2 showed homozygous mutations whereas another 32 were heterozygous for GJB2 gene mutation. Only 31 DNA samples of students presented with sensorineural hearing loss with heterozygous mutation in GJB2 gene were included in this study. The sequencing results obtained were analyzed. The degree of hearing loss of those students with association between GJB2 mutation and GJB6 mutation will be discussed. Five out of 31 subjects (16.2%) have mutations in their GJB6 gene, suggesting a digenic inheritance of GJB2/GJB6 mutation. In total, four novel mutations were identified; E137D (n=1), R32Q (n=1), E101K (n=1) and Y156H (n=1) and one mutation deletion; 366delT (n=1). All students with association GJB2 mutation and GJB6 showed severe to profound hearing loss in both ears. Interestingly this study not detected the large deletion of 342 kb in GJB6 gene suggesting that the mutation is very rare in this region compared to certain parts of the world.
    Matched MeSH terms: Connexins/genetics*
  7. Mohd Kamal DA, Ibrahim SF, Mokhtar MH
    Bosn J Basic Med Sci, 2020 Aug 03;20(3):293-302.
    PMID: 31881167 DOI: 10.17305/bjbms.2019.4501
    The functions of androgen and connexin in the mammalian female reproductive system are suggested to be related. Previous research has shown that androgen affects connexin expression in the female reproductive system, altering its function. However, no definitive conclusion on their cause-effect relationship has been drawn yet. In addition, a high prevalence of women with polycystic ovary syndrome (PCOS), who are characterized by elevated androgen levels and failure of ovulation, has prompted the studies on the relationship between androgen and connexin in the ovaries. This systematic review aims to investigate the effect of androgen on connexin expression in the mammalian female reproductive system. The literature search was conducted using the MEDLINE via EBSCOhost and the Scopus database and the following keywords: "androgen" or "testosterone" or "androgen blocker" or "anti-androgen" or "androstenedione" or "dehydroepiandrosterone" or "flut-amide AND connexin" or "gap junction" or "cell junction". We only considered in vitro and in vivo studies that involved treatment by androgen or androgen receptor blockers and measured connexin expression as one of the parameters. Our review showed that the exposure to androgen or androgen blocker affects connexin expression but not its localization in the mammalian ovary. However, it is not clear whether androgen downregulates or upregulates connexin expression.
    Matched MeSH terms: Connexins/metabolism*
  8. Chow YP, Abdul Murad NA, Mohd Rani Z, Khoo JS, Chong PS, Wu LL, et al.
    Orphanet J Rare Dis, 2017 Feb 21;12(1):40.
    PMID: 28222800 DOI: 10.1186/s13023-017-0575-7
    BACKGROUND: Pendred syndrome (PDS, MIM #274600) is an autosomal recessive disorder characterized by congenital sensorineural hearing loss and goiter. In this study, we describing the possible PDS causal mutations in a Malaysian family with 2 daughters diagnosed with bilateral hearing loss and hypothyroidism.

    METHODS AND RESULTS: Whole exome sequencing was performed on 2 sisters with PDS and their unaffected parents. Our results showed that both sisters inherited monoallelic mutations in the 2 known PDS genes, SLC26A4 (ENST00000265715:c.1343C > T, p.Ser448Leu) and GJB2 (ENST00000382844:c.368C > A, p.Thr123Asn) from their father, as well as another deafness-related gene, SCARB2 (ENST00000264896:c.914C > T, p.Thr305Met) from their mother. We postulated that these three heterozygous mutations in combination may be causative to deafness, and warrants further investigation. Furthermore, we also identified a compound heterozygosity involving the DUOX2 gene (ENST00000603300:c.1588A > T:p.Lys530* and c.3329G > A:p.Arg1110Gln) in both sisters which are inherited from both parents and may be correlated with early onset of goiter. All the candidate mutations were predicted deleterious by in silico tools.

    CONCLUSIONS: In summary, we proposed that PDS in this family could be a polygenic disorder which possibly arises from a combination of heterozygous mutations in SLC26A4, GJB2 and SCARB2 which associated with deafness, as well as compound heterozygous DUOX2 mutations which associated with thyroid dysfunction.

    Matched MeSH terms: Connexins/genetics; Connexins/metabolism*
  9. Kamal DAM, Ibrahim SF, Mokhtar MH
    In Vivo, 2020 7 2;34(4):1863-1870.
    PMID: 32606156 DOI: 10.21873/invivo.11981
    BACKGROUND/AIM: It was hypothesized that testosterone could affect the distribution and expression of connexin 26 and connexin 43 in the uterus. Thus, the effects of testosterone on these parameters in the uterus during the uterine receptivity period were investigated.

    MATERIALS AND METHODS: Intact pregnant rats were administered 1 mg/kg/day testosterone alone or in combination with flutamide, finasteride or anastrozole, subcutaneously on day-1 of pregnancy till day 3. The rats were sacrificed at day 4 of pregnancy, which was considered as the uterine receptivity period for determining the expression and distribution of connexin 26 and connexion 43 by immunohistochemistry and quantitative polymerase chain reaction, respectively.

    RESULTS: Treatment with 1 mg/kg/day testosterone increased connexin 26 and decreased connexin 43 mRNA expression and protein distribution in the uterus of early pregnancy rats.

    CONCLUSION: Changes in the uterine connexin 26 and connexin 43 expression by testosterone could disrupt embryo implantation, resulting in early pregnancy loss.

    Matched MeSH terms: Connexins
  10. Aishah ZS, Khairi MD, Normastura AR, Zafarina Z, Zilfalil BA
    J Laryngol Otol, 2008 Dec;122(12):1284-8.
    PMID: 18353197 DOI: 10.1017/S0022215108002041
    To determine the frequency and type of gap junction protein beta-2 gene mutations in Malay patients with autosomal recessive, non-syndromic hearing loss.
    Matched MeSH terms: Connexins/genetics*
  11. Shahrizaila N, Samulong S, Tey S, Suan LC, Meng LK, Goh KJ, et al.
    Muscle Nerve, 2014 Feb;49(2):198-201.
    PMID: 23649551 DOI: 10.1002/mus.23892
    Data regarding Charcot-Marie-Tooth disease is lacking in Southeast Asian populations. We investigated the frequency of the common genetic mutations in a multiethnic Malaysian cohort.
    Matched MeSH terms: Connexins/genetics
  12. Mat Nor MN, Rupenthal ID, Green CR, Acosta ML
    Neurotherapeutics, 2020 Jan;17(1):371-387.
    PMID: 31637594 DOI: 10.1007/s13311-019-00786-5
    Increased Connexin43 hemichannel opening is associated with inflammasome pathway activation and inflammation in a range of pathologies including ocular disorders, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). In this study, the effect on retinal function and morphology of clinically safe doses of orally delivered tonabersat, a small molecule connexin hemichannel blocker, was investigated in the light-damaged retina animal model of dry AMD and in a spontaneous rat model of DR. Clinical parameters (fundus imaging, optical coherence tomography (OCT), and electroretinography) and inflammatory markers (immunohistochemistry for Iba-1 microglial marker, astrocyte marker glial fibrillary acidic protein, and Connexin43 protein expression) were assessed. Tonabersat treatment reduced inflammation in the retina in parallel with preservation of retinal photoreceptor function when assessed up to 3 months post light damage in the dry AMD model. In the DR model, clinical signs, including the presence of aneurysms confirmed using Evans blue dye perfusion, were reduced after daily tonabersat treatment for 2 weeks. Inflammation was also reduced and retinal electrical function restored. Tonabersat regulates assembly of the inflammasome (NLRP3) through Connexin43 hemichannel block, with the potential to reduce inflammation, restore vascular integrity and improve anatomical along with some functional outcomes in retinal disease.
    Matched MeSH terms: Connexins/antagonists & inhibitors*
  13. Kim Y, Griffin JM, Nor MNM, Zhang J, Freestone PS, Danesh-Meyer HV, et al.
    Neurotherapeutics, 2017 Oct;14(4):1148-1165.
    PMID: 28560708 DOI: 10.1007/s13311-017-0536-9
    The cis benzopyran compound tonabersat (SB-220453) has previously been reported to inhibit connexin26 expression in the brain by attenuating the p38-mitogen-activated protein kinase pathway. We show here that tonabersat directly inhibits connexin43 hemichannel opening. Connexin43 hemichannels have been called "pathological pores" based upon their role in secondary lesion spread, edema, inflammation, and neuronal loss following central nervous system injuries, as well as in chronic inflammatory disease. Both connexin43 hemichannels and pannexin channels released adenosine triphosphate (ATP) during ischemia in an in vitro ischemia model, but only connexin43 hemichannels contributed to ATP release during reperfusion. Tonabersat inhibited connexin43 hemichannel-mediated ATP release during both ischemia and reperfusion phases, with direct channel block confirmed using electrophysiology. Tonabersat also reduced connexin43 gap junction coupling in vitro, but only at higher concentrations, with junctional plaques internalized and degraded via the lysosomal pathway. Systemic delivery of tonabersat in a rat bright-light retinal damage model (a model for dry age-related macular degeneration) resulted in significantly improved functional outcomes assessed using electroretinography. Tonabersat also prevented thinning of the retina, especially the outer nuclear layer and choroid, assessed using optical coherence tomography. We conclude that tonabersat, already given orally to over 1000 humans in clinical trials (as a potential treatment for, and prophylactic treatment of, migraine because it was thought to inhibit cortical spreading depression), is a connexin hemichannel inhibitor and may have the potential to be a novel treatment of central nervous system injury and chronic neuroinflammatory disease.
    Matched MeSH terms: Connexins/metabolism
  14. Mat Nor MN, Rupenthal ID, Green CR, Acosta ML
    Int J Mol Sci, 2021 Feb 10;22(4).
    PMID: 33578721 DOI: 10.3390/ijms22041755
    Dysregulation of retinal function in the early stages of light-induced retinal degeneration involves pannexins and connexins. These two types of proteins may contribute to channels that release ATP, leading to activation of the inflammasome pathway, spread of inflammation and retinal dysfunction. However, the effect of pannexin channel block alone or block of both pannexin channels and connexin hemichannels in parallel on retinal activity in vivo is unknown. In this study, the pannexin channel blocker probenecid and the connexin hemichannel blocker tonabersat were used in the light-damaged rat retina. Retinal function was evaluated using electroretinography (ERG), retinal structure was analyzed using optical coherence tomography (OCT) imaging and the tissue response to light-induced injury was assessed immunohistochemically with antibodies against glial fibrillary acidic protein (GFAP), Ionized calcium binding adaptor molecule 1 (Iba-1) and Connexin43 (Cx43). Probenecid did not further enhance the therapeutic effect of connexin hemichannel block in this model, but on its own improved activity of certain inner retina neurons. The therapeutic benefit of blocking connexin hemichannels was further evaluated by comparing these data against results from our previously published studies that also used the light-damaged rat retina model. The analysis showed that treatment with tonabersat alone was better than probenecid alone at restoring retinal function in the light-damaged retina model. The results assist in the interpretation of the differential action of connexin hemichannel and pannexin channel therapeutics for potential treatment of retinal diseases.
    Matched MeSH terms: Connexins/antagonists & inhibitors*
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