Febs Letters

Trchounian, Karen; Trchounian, Armen

doi: 10.1016/j.febslet.2013.09.016pmid: 24060380

Escherichia coli evolves H2 via multiple [Ni–Fe]‐hydrogenases (Hyd). This activity under hyper‐ and hypo‐osmotic stress was investigated with mutants lacking different Hyd enzymes during glycerol fermentation. Inhibitory effects of hypo‐stress on H2 production was stronger at pH 6.5 in wild type and mutants except fhlA, which encodes a transcriptional activator for Hyd‐3, compared with the effects of N,N′‐dicyclohexylcarbodiimide. These results indicate that Hyd‐3 and Hyd‐4 are osmosensitive at pH 7.5. Hyd‐4 and FhlA are implicated in osmotic stress response at pH 6.5. Hyd‐1 and FhlA might be osmosensitive at pH 5.5. Thus, osmosensitivity of Hyd enzymes is a novel property that depends on pH. This is significant for mechanisms of cell osmoregulation and H2 production biotechnology when glycerol is used as a fermentation substrate.

Roy, Avik; Pahan, Kalipada

doi: 10.1016/j.febslet.2013.09.020pmid: 24076025

Aggregation of α‐synuclein is a pathological hallmark of sporadic or familial PD. However, the detailed molecular mechanism responsible for the aggregation of α‐synuclein has not been properly explored. In the present study, we have identified a novel role of an anti‐tumorigenic BTB/POZ domain containing protein‐2 (BPOZ‐2) in the regulation of α‐synuclein accumulation in dopaminergic (DA) neurons. MPP+, an etiological factor for PD, significantly downregulated the expression of BPOZ‐2 ahead of α‐synuclein upregulation. Moreover, siRNA knockdown of BPOZ‐2 alone stimulated the aggregation of α‐synuclein protein; the effect was further induced in presence of MPP+ in mouse primary DA neurons. Finally, the absence of BPOZ‐2 in α‐synuclein expressing neuronal populations of MPTP‐intoxicated mouse and primate nigra indicates that the suppression of BPOZ‐2 could be involved in the accumulation of α‐synuclein protein.

Tomikawa, Chie; Ohira, Takayuki; Inoue, Yasushi; Kawamura, Takuya; Yamagishi, Akihiko; Suzuki, Tsutomu; Hori, Hiroyuki

doi: 10.1016/j.febslet.2013.09.021pmid: 24076028

Thermoplasma acidophilum is a thermo‐acidophilic archaeon. We purified tRNALeu (UAG) from T. acidophilum using a solid‐phase DNA probe method and determined the RNA sequence after determining via nucleoside analysis and m7G‐specific aniline cleavage because it has been reported that T. acidophilum tRNA contains m7G, which is generally not found in archaeal tRNAs. RNA sequencing and liquid chromatography–mass spectrometry revealed that the m7G modification exists at a novel position 49. Furthermore, we found several distinct modifications, which have not previously been found in archaeal tRNA, such as 4‐thiouridine9, archaeosine13 and 5‐carbamoylmethyuridine34. The related tRNA modification enzymes and their genes are discussed.

Ratovitski, Edward A.

doi: 10.1016/j.febslet.2013.09.023pmid: 24070899

Cisplatin‐induced and ATM‐phosphorylated (p)‐ΔNp63α regulates the expression of epidermal differentiation and skin barrier regulators (AQP3, CASP14, ALOX12B, and CLDN1) in squamous cell carcinoma (SCC) cells by dual transcriptional and post‐transcriptional mechanisms. We found that p‐ΔNp63α bound to target gene promoters, and regulated the activity of the tested promoters in vitro. P‐ΔNp63α was shown to upregulate miR‐185‐5p and downregulate let7‐5p, which subsequently modulated AQP3, CASP14, ALOX12B and CLDN1 through their respective 3′‐untranslated regions. The introduction of miR‐185‐5p into resistant SCC‐11M cells, which are unable to phosphorylate ΔNp63α, render these cells more sensitive to cisplatin treatment. Further studies of the AQP3, CASP14, ALOX12B, and CLDN1 contributions to chemoresistance may assist in developing novel microRNA‐based therapies for human SCC.

Xu, Wangyang; Zhu, Houbao; Gu, Mingmin; Luo, Qingqiong; Ding, Jieying; Yao, Yuting; Chen, Fuxiang; Wang, Zhugang

doi: 10.1016/j.febslet.2013.08.047pmid: 24076469

Maintaining the functional integrity of mitochondria is crucial for cell function, signal transduction and overall cell activities. Mitochondrial dysfunctions may alter energy metabolism and in many cases are associated with neurological diseases. Recent studies have reported that mutations in dehydrogenase E1 and transketolase domain‐containing 1 (DHTKD1), a mitochondrial protein encoding gene, could cause neurological abnormalities. However, the function of DHTKD1 in mitochondria remains unknown. Here, we report a strong correlation of DHTKD1 expression level with ATP production, revealing the fact that DHTKD1 plays a critical role in energy production in mitochondria. Moreover, suppression of DHTKD1 leads to impaired mitochondrial biogenesis and increased reactive oxygen species (ROS), thus leading to retarded cell growth and increased cell apoptosis. These findings demonstrate that DHTKD1 contributes to mitochondrial biogenesis and function maintenance.

doi: 10.1016/j.febslet.2013.09.026pmid: N/A