Richard Aldrich

Publications (45) View all

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  Available from: Richard Aldrich

  Article: Intragenic alternative splicing coordination is essential for Caenorhabditis elegans slo-1 gene function.

  Dominique A Glauser, Brandon E Johnson, Richard W Aldrich, Miriam B Goodman
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  ABSTRACT: Alternative splicing is critical for diversifying eukaryotic proteomes, but the rules governing and coordinating splicing events among multiple alternate splice sites within individual genes are not well understood. We developed a quantitative PCR-based strategy to quantify the expression of the 12 transcripts encoded by the Caenorhabditis elegans slo-1 gene, containing three alternate splice sites. Using conditional probability-based models, we show that splicing events are coordinated across these sites. Further, we identify a point mutation in an intron adjacent to one alternate splice site that disrupts alternative splicing at all three sites. This mutation leads to aberrant synaptic transmission at the neuromuscular junction. In a genomic survey, we found that a UAAAUC element disrupted by this mutation is enriched in introns flanking alternate exons in genes with multiple alternate splice sites. These results establish that proper coordination of intragenic alternative splicing is essential for normal physiology of slo-1 in vivo and identify putative specialized cis-regulatory elements that regulate the coordination of intragenic alternative splicing.
  Proceedings of the National Academy of Sciences 11/2011; 108(51):20790-5. · 9.68 Impact Factor
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  Available from: Richard Aldrich

  Article: Alternatively spliced domains interact to regulate BK potassium channel gating.

  Brandon E Johnson, Dominique A Glauser, Elise S Dan-Glauser, D Brent Halling, Richard W Aldrich, Miriam B Goodman
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  ABSTRACT: Most human genes contain multiple alternative splice sites believed to extend the complexity and diversity of the proteome. However, little is known about how interactions among alternative exons regulate protein function. We used the Caenorhabditis elegans slo-1 large-conductance calcium and voltage-activated potassium (BK) channel gene, which contains three alternative splice sites (A, B, and C) and encodes at least 12 splice variants, to investigate the functional consequences of alternative splicing. These splice sites enable the insertion of exons encoding part of the regulator of K(+) conductance (RCK)1 Ca(2+) coordination domain (exons A1 and A2) and portions of the RCK1-RCK2 linker (exons B0, B1, B2, C0, and C1). Exons A1 and A2 are used in a mutually exclusive manner and are 67% identical. The other exons can extend the RCK1-RCK2 linker by up to 41 residues. Electrophysiological recordings of all isoforms show that the A1 and A2 exons regulate activation kinetics and Ca(2+) sensitivity, but only if alternate exons are inserted at site B or C. Thus, RCK1 interacts with the RCK1-RCK2 linker, and the effect of exon variation on gating depends on the combination of alternate exons present in each isoform.
  Proceedings of the National Academy of Sciences 11/2011; 108(51):20784-9. · 9.68 Impact Factor
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  Available from: Richard Aldrich

  Article: Charge substitution for a deep-pore residue reveals structural dynamics during BK channel gating.

  Xixi Chen, Richard W Aldrich
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  ABSTRACT: The pore-lining amino acids of ion channel proteins reside on the interface between a polar (the pore) and a nonpolar environment (the rest of the protein). The structural dynamics of this region, which physically controls ionic flow, are essential components of channel gating. Using large-conductance, Ca(2+)-dependent K(+) (BK) channels, we devised a systematic charge-substitution method to probe conformational changes in the pore region during channel gating. We identified a deep-pore residue (314 in hSlo1) as a marker of structural dynamics. We manipulated the charge states of this residue by substituting amino acids with different valence and pKa, and by adjusting intracellular pH. We found that the charged states of the 314 residues stabilized an open state of the BK channel. With models based on known structures of related channels, we postulate a dynamic rearrangement of the deep-pore region during BK channel opening/closing, which involves a change of the degree of pore exposure for 314.
  The Journal of General Physiology 08/2011; 138(2):137-54. · 3.84 Impact Factor
• Article: Tissue-specific N terminus of the HCN4 channel affects channel activation.

  He Liu, Richard W Aldrich
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  ABSTRACT: Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed in the brain and heart and are essential for physiological functions in cardiac and nervous systems. We identified two Hcn4 mRNA variants with different transcription start sites and differential expression patterns in mouse brain and heart. Only one mRNA variant was detected in the brain, whereas both variants were found in the heart. Patch clamp recordings of these two variants in HEK293H cells revealed different electrophysiological properties in channel activation. Mutagenesis studies showed that three positively charged amino acids (Arg-9, Lys-10, and Lys-22) contribute to the functional difference. Our results demonstrate that HCN4 channels are expressed in different patterns in mouse brain and heart and that the N terminus is important for HCN4 channel activation.
  Journal of Biological Chemistry 03/2011; 286(16):14209-14. · 4.77 Impact Factor
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  Available from: Richard Aldrich

  Article: Electrostatic influences of charged inner pore residues on the conductance and gating of small conductance Ca2+ activated K+ channels.

  Weiyan Li, Richard W Aldrich
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  ABSTRACT: SK channels underlie important physiological functions by linking calcium signaling with neuronal excitability. Potassium currents through SK channels demonstrate inward rectification, which further reduces their small outward conductance. Although it has been generally attributed to block of outward current by intracellular divalent ions, we find that inward rectification is in fact an intrinsic property of SK channels independent of intracellular blockers. We identified three charged residues in the S6 transmembrane domain of SK channels near the inner mouth of the pore that collectively control the conductance and rectification through an electrostatic mechanism. Additionally, electrostatic contributions from these residues also play an important role in determining the intrinsic open probability of SK channels in the absence of Ca(2+), affecting the apparent Ca(2+) affinity for activation.
  Proceedings of the National Academy of Sciences 03/2011; 108(15):5946-53. · 9.68 Impact Factor