The “structurally minimal” isoform KChIP2d modulates recovery of Kv4.3 N-terminal deletion mutant Δ2-39

Mechanisms underlying Kv4 (Shal type) potassium channel macroscopic (open state) inactivation and recovery are unknown, as are mechanisms by which KChIP2 isoforms modulate these two processes. In a recent study (Xenopus oocytes, 2 microelectrode voltage clamp) we demonstrated that: i) Partial deletion of the Kv4.3 proximal N-terminal domain (Δ2-39; deletes N-terminal amino acids 2–39) not only slowed macroscopic inactivation, but also slowed the net rate of recovery; and ii) Co-expression of KChIP2b significantly accelerated the rate Δ2-39 recovery from inactivation. The latter effect demonstrated that an intact N-terminal domain was not obligatorily required for KChiP2b-mediated modulation of Kv4.3 recovery. To extend these prior observations, we have employed identical protocols to determine effects of KChiP2d on Δ2-39 macroscopic recovery. KChiP2d is a “structurally minimal” isoform (consisting of only the last 70 amino acids of the common C-terminal domain of larger KChIP2 isoforms) that exerts functional modulatory effects on native Kv4.3 channels. We demonstrate that KChiP2d also accelerates Δ2-39 recovery from macroscopic inactivation. Consistent with our prior Δ2-39 + KChIP2b study, these Δ2-39 + KChIP2d results: i) Further indicate that KChIP2 isoform-mediated acceleration of Kv4.3 macroscopic recovery is not obligatorily dependent upon an intact proximal N-terminal; and ii) Suggest that the last 70 amino acids of the common C-terminal of KChiP2 isoforms may contain the domain(s) responsible for modulation of recovery

KV4.3 N-terminal deletion mutant Δ2–39: Effects on inactivation and recovery characteristics in both the absence and presence of KChIP2b

Gating transitions in the KV4.3 N-terminal deletion mutant Δ2–39 were characterized in the absence and presence of KChIP2b. We particularly focused on gating characteristics of macroscopic (open state) versus closed state inactivation (CSI) and recovery. In the absence of KChIP2b Δ2–39 did not significantly alter the steady-state activation “a4” relationship or general CSI characteristics, but it did slow the kinetics of deactivation, macroscopic inactivation and macroscopic recovery. Recovery kinetics (for both WT KV4.3 and Δ2–39) were complicated and displayed sigmoidicity, a process which was enhanced by Δ2–39. Deletion of the proximal N-terminal domain therefore appeared to specifically slow mechanisms involved in regulating gating transitions occurring after the channel open state(s) had been reached. In the presence of KChIP2b Δ2–39 recovery kinetics (from both macroscopic and CSI) were accelerated, with an apparent reduction in initial sigmoidicity. Hyperpolarizing shifts in both “a4” and isochronal inactivation “i” were also produced. KChIP2b-mediated remodeling of KV4.3 gating transitions was therefore not obligatorily dependent upon an intact N-terminus. To account for these effects we propose that KChIP2 regulatory domains exist in KV4.3 α subunit regions outside of the proximal N-terminal. In addition to regulating macroscopic inactivation, we also propose that the KV4.3 N-terminus may act as a novel regulator of deactivation-recovery coupling

Brief Report: HIV Drug Resistance in Adults Failing Early Antiretroviral Treatment: Results From the HIV Prevention Trials Network 052 Trial

Submitted by Sandra Infurna ([email protected]) on 2017-12-21T12:34:31Z No. of bitstreams: 1 mariza_morgado_etal_IOC_2016.pdf: 137842 bytes, checksum: 9c34307109b7b6cd29edde12809a3008 (MD5)Approved for entry into archive by Sandra Infurna ([email protected]) on 2017-12-21T13:02:47Z (GMT) No. of bitstreams: 1 mariza_morgado_etal_IOC_2016.pdf: 137842 bytes, checksum: 9c34307109b7b6cd29edde12809a3008 (MD5)Made available in DSpace on 2017-12-21T13:02:47Z (GMT). No. of bitstreams: 1 mariza_morgado_etal_IOC_2016.pdf: 137842 bytes, checksum: 9c34307109b7b6cd29edde12809a3008 (MD5) Previous issue date: 2016Johns Hopkins Univ. School of Medicine. Dept. of Pathology. Baltimore, Maryland, USA.Johns Hopkins Univ. School of Medicine. Dept. of Pathology. Baltimore, Maryland, USA.Fred Hutchinson Cancer Research Center. Vaccine and Infectious Disease Division. Seattle, VA, USA.Frontier Science & Technology Research Foundation. Amherst, NY, USA.Lancet Laboratories and BARC-SA. Specialty Molecular Division. Johannesburg, South Africa.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de AIDS e Imunologia Molecular. Rio de Janeiro, RJ. Brasil.Y. R. Gaitonade Centre for AIDS Research and Education. Chennai, India.National JALMA Institute for Leprosy and Other Mycobacterial Diseases. Agra, India.Frontier Science & Technology Research Foundation. Amherst, NY, USA.Johns Hopkins Univ. School of Medicine. Dept. of Pathology. Baltimore, MD, USA.Johns Hopkins Univ. School of Medicine. Dept. of Pathology. Baltimore, MD, USA.Science Facilitation Department. FHI 360. Washington, DC, USA.Science Facilitation Department. FHI 360, Durham, NC, USA.Fred Hutchinson Cancer Research Center. Vaccine and Infectious Disease Division. Seattle, WA, USA.Univ. of North Carolina at Chapel Hill. Dept. of Medicine. Chapel Hill, NC, USA.Southwest CARE Center. Santa Fe, NM, USA.College of Medicine. Johns Hopkins Project. Blantyre, Malawi.Botswana Harvard AIDS Institute. Gaborone, Botswana.YRGCARE Medical Centre.VHS. Chennai, India.Chiang Mai University. Research Institute for Health Sciences. Chiang Mai, Thailand.University of Zimbabwe. Dept. of Medicine. Harare, Zimbabwe.Univ. of Witwatersrand. Johannesburg, South Africa.Kenya Medical Research Institute. Kisumu, Kenya. / Center for Disease Control. Kisumu, Kenya.Univ. of North Carolina at Chapel Hill. Division of Infectious Diseases. Chapel Hill, NC, USA / UNC Project-Malawi. Institute for Global Health and Infectious Diseases. Lilongwe, Malawi.Hospital Nossa Senhora da Conceição. Serviço de Infectologia. Porto Alegre, RS, Brasil.National AIDS Research Institute (ICMR). Pune, India.Hospital Geral de Nova Iguacu. Nova Iguaçu, RJ, Brasil / Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de AIDS e Imunologia Molecular. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Instituto Nacional de Infectologia Evandro Chagas. Rio de Janeiro, RJ, Brasil.University of the Witwatersrand. Perinatal HIV Research Unit. Soweto, South Africa.The Fenway Institute. Fenway Health and Infectious Disease Division. Boston, MA, USA / Harvard Medical School. Beth Israel Deaconess Medical Center/Dept. of Medicine. Boston, MA, USA.Fred Hutchinson Cancer Research Center. Vaccine and Infectious Disease Division and Public Health Sciences Division. Seattle, VA, USA.Univ. of North Carolina at Chapel Hill. Department of Medicine. Chapel Hill, NC, USA.Univ. of North Carolina at Chapel Hill. Dept. of Pathology. Baltimore, MD, USA.Early initiation of antiretroviral treatment (ART) reduces HIV transmission and has health benefits. HIV drug resistance can limit treatment options and compromise use of ART for HIV prevention. We evaluated drug resistance in 85 participants in the HIV Prevention Trials Network 052 trial who started ART at CD4 counts of 350-550 cells per cubic millimeter and failed ART by May 2011; 8.2% had baseline resistance and 35.3% had resistance at ART failure. High baseline viral load and less education were associated with emergence of resistance at ART failure. Resistance at ART failure was observed in 7 of 8 (87.5%) participants who started ART at lower CD4 cell counts

Brief Report: HIV Drug Resistance in Adults Failing Early Antiretroviral Treatment: Results From the HIV Prevention Trials Network 052 Trial

Early initiation of antiretroviral therapy (ART) reduces HIV transmission and has health benefits. HIV drug resistance can limit treatment options and compromise use of ART for HIV prevention. We evaluated drug resistance in 85 participants in the HPTN 052 trial who started ART at CD4 counts of 350–550 cells/mm(3) and failed ART by May 2011; 8.2% had baseline resistance and 35.3% had resistance at ART failure. High baseline viral load and less education were associated with emergence of resistance at ART failure. Resistance at ART failure was observed in 7/8 (87.5%) participants who started ART at lower CD4 cell counts