Oocyte activation and latent HIV-1 reactivation: AMPK as a common mechanism of action linking the beginnings of life and the potential eradication of HIV-1

详细信息    查看全文

• 作者：Jahahreeh Finley ; ^{jfinley4@alumni.jh.edu" class="auth_mail" title="E-mail the corresponding author} ; ^{jahahreeh@hotmail.com" class="auth_mail" title="E-mail the corresponding author}
• 关键词：AMP-activated protein kinase (AMPK) ; Oocyte ; HIV-1 latency ; Hutchinson&ndash ; Gilford progeria syndrome (HGPS) ; LKB1 ; CaMKK2 ; Phospholipase C zeta (PLCζ) ; Phospholipase C-gamma 1 (PLCγ1) ; Bryostatin ; Resveratrol ; Metformin ; Retinoic acid
• 刊名：Medical Hypotheses
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：93
• 期：Complete
• 页码：34-47
• 全文大小：558 K

文摘

In all mammalian species studied to date, the initiation of oocyte activation is orchestrated through alterations in intracellular calcium (Ca²⁺) signaling. Upon sperm binding to the oocyte plasma membrane, a sperm-associated phospholipase C (PLC) isoform, PLC zeta (PLCζ), is released into the oocyte cytoplasm. PLCζ hydrolyzes phosphatidylinositol 4,5-bisphosphate (PIP2) to produce diacylglycerol (DAG), which activates protein kinase C (PKC), and inositol 1,4,5-trisphosphate (IP3), which induces the release of Ca²⁺ from endoplasmic reticulum (ER) Ca²⁺ stores. Subsequent Ca²⁺ oscillations are generated that drive oocyte activation to completion. Ca²⁺ ionophores such as ionomycin have been successfully used to induce artificial human oocyte activation, facilitating fertilization during intra-cytoplasmic sperm injection (ICSI) procedures. Early studies have also demonstrated that the PKC activator phorbol 12-myristate 13-acetate (PMA) acts synergistically with Ca²⁺ ionophores to induce parthenogenetic activation of mouse oocytes. Interestingly, the Ca²⁺-induced signaling cascade characterizing sperm or chemically-induced oocyte activation, i.e. the “shock and live” approach, bears a striking resemblance to the reactivation of latently infected HIV-1 viral reservoirs via the so called “shock and kill” approach, a method currently being pursued to eradicate HIV-1 from infected individuals. PMA and ionomycin combined, used as positive controls in HIV-1 latency reversal studies, have been shown to be extremely efficient in reactivating latent HIV-1 in CD4⁺ memory T cells by inducing T cell activation. Similar to oocyte activation, T cell activation by PMA and ionomycin induces an increase in intracellular Ca²⁺ concentrations and activation of DAG, PKC, and downstream Ca²⁺-dependent signaling pathways necessary for proviral transcription. Interestingly, AMPK, a master regulator of cell metabolism that is activated thorough the induction of cellular stress (e.g. increase in Ca²⁺ concentration, reactive oxygen species generation, increase in AMP/ATP ratio) is essential for oocyte maturation, T cell activation, and mitochondrial function. In addition to the AMPK kinase LKB1, CaMKK2, a Ca²⁺/calmodulin-dependent kinase that also activates AMPK, is present in and activated on T cell activation and is also present in mouse oocytes and persists until the zygote and two-cell stages. It is our hypothesis that AMPK activation represents a central node linking T cell activation-induced latent HIV-1 reactivation and both physiological and artificial oocyte activation. We further propose the novel observation that various compounds that have been shown to reactivate latent HIV-1 (e.g. PMA, ionomycin, metformin, bryostatin, resveratrol, etc.) or activate oocytes (PMA, ionomycin, ethanol, puromycin, etc.) either alone or in combination likely do so via stress-induced activation of AMPK.