Chengfeng Xiao

Cyclic guanosine monophosphate (cGMP) modulates the speed of recovery from anoxia in adult Drosophila and mediates hypoxia-related behaviors in larvae. Cyclic nucleotide-gated channels (CNG) and cGMP-activated protein kinase (PKG) are two cGMP downstream targets. PKG is involved in behavioral tolerance to hypoxia and anoxia in adults, however little is known about a role for CNG channels. We used a CNGL (CNG-like) mutant with reduced CNGL transcripts to investigate the contribution of CNGL to the hypoxia response. CNGL mutants had reduced locomotor activity under normoxia. A shorter distance travelled in a standard locomotor assay was due to a slower walking speed and more frequent stops. In control flies, hypoxia immediately reduced path length per minute. Flies took 30–40 min in normoxia for >90% recovery of path length per minute from 15 min hypoxia. CNGL mutants had impaired recovery from hypoxia; 40 min for ∼10% recovery of walking speed. The effects of CNGL mutation on locomotor activity and recovery from hypoxia were recapitulated by pan-neuronal CNGL knockdown. Genetic manipulation to increase cGMP in the CNGL mutants increased locomotor activity under normoxia and eliminated the impairment of recovery from hypoxia. We conclude that CNGL channels and cGMP signaling are involved in the control of locomotor activity and the hypoxic response of adult Drosophila.

Extensive inflammation and apoptosis in structural cells of the lung are responsible for the progression and pathogenesis of chronic obstructive pulmonary disease (COPD). Myotubularin‐related protein 14 (MTMR14) has been shown to participate in various biological processes, including apoptosis, inflammation, and autophagy. Nonetheless, the role of MTMR14 in COPD remains elusive. In the present study, we explored the expression of MTMR14 in human lung tissues and investigated the effects of overexpressed MTMR14 on in vitro and in vivo COPD models. Moreover, one of the possible mechanisms of MTMR14 alleviating COPD was explored based on mitochondrial function and mitophagy homeostasis. The results showed that MTMR14 expression was reduced in COPD patients’ lungs in comparison to control subjects. MTMR14 overexpression inhibited cigarette smoke extract‐induced inflammation and apoptosis and improved mitochondrial function and mitophagy in vitro. Further verification was carried out in COPD model mice. MTMR14 overexpression inhibited lung inflammation and reduced levels of IL‐6 and KC in bronchoalveolar lavage fluid, as well as prevented emphysema and a decline in lung function. Furthermore, MTMR14 overexpression improved mitochondrial function and mitophagy to a certain extent. Collectively, our data support the hypothesis that MTMR14 participates in the pathogenesis of COPD. Improving mitochondrial function and mitophagy homeostasis may be one of the mechanisms by which MTMR14 alleviates COPD and may potentially be a novel therapeutic target for COPD.

Chronic obstructive pulmonary disease (COPD) is composed of chronic airway inflammation and emphysema. Recent studies show that Class IA phosphatidylinositol 3-kinases (PI3Ks) play an important role in the regulation of inflammation and emphysema. However, there are few studies on their regulatory subunits. p55PIK is a regulatory subunit of Class IA PI3Ks, and its unique NH₂-terminal gives it special functions. p55PIK expression in the lungs of nonsmokers, smokers, and patients with COPD was examined. We established a fusion protein TAT-N15 from the NH₂-terminal effector sequence of p55PIK and TAT (the transduction domain of HIV transactivator protein) and investigated the effects of silencing p55PIK or adding TAT-N15 on cigarette smoke exposure at the cellular and animal level. p55PIK expression was increased in patients with COPD. p55PIK deficiency and TAT-N15 significantly inhibited the cigarette smoke extract-induced IL-6, IL-8, and activation of the Akt and the NF-κB pathway in BEAS-2B. p55PIK deficiency and TAT-N15 intranasal administration prevented emphysema and the lung function decline in mice exposed to smoke for 6 mo. p55PIK deficiency and TAT-N15 significantly inhibited lung inflammatory infiltration, reduced levels of IL-6 and KC in mice lung homogenate, and inhibited activation of the Akt and the NF-κB signaling in COPD mice lungs. Our studies indicate that p55PIK is involved in the pathogenesis of COPD, and its NH₂-terminal derivative TAT-N15 could be an effective drug in the treatment of COPD by inhibiting the activation of the Akt and the NF-κB pathway.

Drosophila provides an excellent opportunity to explore the genetic basis for behavioral and CNS responses to hypoxia. Cyclic guanosine monophosphate (cGMP) modulates the speed of recovery from anoxia in adults and mediates hypoxia-related behaviors in larvae. Cyclic nucleotide-gated channels (CNG) and cGMP-activated protein kinase (PKG) are two cGMP downstream targets. PKG is involved in behavioral tolerance to hypoxia and anoxia in adults, however little is known about CNG channels. We used a CNGL mutant with reduced CNGL transcripts to investigate the contribution of CNGL to the hypoxia response. In control flies (w1118), hypoxia immediately reduced path length per minute in a locomotor assay. Flies took 30-40 mins in air to recover from 15 mins hypoxia. CNGL mutants had reduced locomotion under normoxia and impaired recovery from hypoxia, similar to the effects of pan-neural CNGL knockdown. In the CNGL mutants hypoxia caused an acute increase in path length per minute followed by a gradual increase during hypoxia. Basal levels of CNS extracellular K ⁺ concentrations were reduced in the mutants. In response to hypoxia, the mutants had an increased extracellular K ⁺ concentration change, reduced time to reach the K ⁺ concentration peak, and delayed recovery time. Genetic manipulation to increase cGMP in the CNGL mutants eliminated the impairment of recovery from hypoxia and partially compensated for the effects of hypoxia on CNS K ⁺ . Although the neural mechanisms have yet to be determined, CNGL channels and cGMP signaling are involved in the hypoxia response of adult Drosophila .

The classic eye‐color gene white (w) in Drosophila melanogaster (fruitfly) has unexpected behavioral consequences. How w affects locomotion of adult flies is largely unknown. Here, we show that a mutant allele (w¹¹¹⁸) selectively increases locomotor components at relatively high frequencies (> 0.1 Hz). The w¹¹¹⁸ flies had reduced transcripts of w⁺ from the 5′ end of the gene. Male flies of w¹¹¹⁸ walked continuously in circular arenas while the wildtype Canton‐S walked intermittently. Through careful control of genetic and cytoplasmic backgrounds, we found that the w¹¹¹⁸ locus was associated with continuous walking. w¹¹¹⁸‐carrying male flies showed increased median values of path length per second (PPS) and 5‐min path length compared with w⁺‐carrying males. Additionally, flies carrying 2–4 genomic copies of mini‐white⁺ (mw⁺) in the w¹¹¹⁸ background showed suppressed median PPSs and decreased 5‐min path length compared with controls, and the suppression was dependent on the copy number of mw⁺. Analysis of the time‐series (i.e., PPSs over time) by Fourier transform indicated that w¹¹¹⁸ was associated with increased locomotor components at relatively high frequencies (> 0.1 Hz). The addition of multiple genomic copies of mw⁺ (2–4 copies) suppressed the high‐frequency components. Lastly, the downregulation of w⁺ in neurons but not glial cells resulted in increased high‐frequency components. We concluded that mutation of w modified the locomotion in adult flies by selectively increasing high‐frequency locomotor components.

The classic eye-color gene white ⁺ ( w ⁺ ) in Drosophila melanogaster (fruitfly) has unexpected behavioral consequences. How w ⁺ affect locomotion of adult flies is largely unknown. Here, we show that w ⁺ selectively suppresses locomotor components at relatively high frequencies (> 0.1 Hz). The wildtype Canton-S male flies walked intermittently in circular arenas while the white-eyed w ¹¹¹⁸ flies walked continuously. Through careful control of genetic and cytoplasmic backgrounds, we found that w ⁺ was associated with intermittent walking. w ⁺ -carrying male flies had smaller median values of path length per second (PPS) and reduced 5-min path length compared with w ¹¹¹⁸ -carrying males. Additionally, flies carrying 2-4 genomic copies of mini- white ⁺ (m w ⁺ ) showed reduced median PPSs and decreased 5-min path length compared with w ¹¹¹⁸ flies, and the suppression was dependent on the copy number of m w ⁺ . Fourier transform of the time series (i.e. PPSs over time) indicated that w ⁺ /m w ⁺ specifically suppressed the locomotor components at relatively high frequencies (> 0.1 Hz). Lastly, the downregulation of w ⁺ in neurons but not glial cells resulted in an increased percentage of high-frequency locomotor components. We concluded that w ⁺ suppressed the locomotion of adult flies by selectively reducing the high-frequency locomotor components.

It has been known for over 20 years that Drosophila melanogaster flies with twelve additional copies of the hsp70 gene encoding the 70 kDa heat shock protein lives longer after a non-lethal heat treatment. Since the heat treatment also induces the expression of additional heat shock proteins, the biological effect can be due either to HSP70 acting alone or in combination. This study used the UAS/GAL4 system to determine whether hsp70 is sufficient to affect the longevity and the resistance to thermal, oxidative or desiccation stresses of the whole organism. We observed that HSP70 expression in the nervous system or muscles has no effect on longevity or stress resistance but ubiquitous expression reduces the life span of males. We also observed that the down-regulation of Hsp70 using RNAi did not affect longevity.